Oladepo Joshua Godspower   Alabi Oladunni Oyelola   Furqan Abdulfattah   and Olatunbosun Ajibola Basheet   

This research investigated the influence of mesh size variation on the efficiency of froth flotation on Anka-Nassarawa copper ore, sourced from Zamfara State, Nigeria. Physical and chemical characterization was carried out, followed by sieve size analysis of the ore, leading to its crushing and grinding to liberation size and processing using froth flotation at sieves 250, 180, 125, 90 and 63 μm. Reagents used were pine oil as a frother, potassium ethyl xanthate as a collector, zinc sulphate – depressant, copper sulphate – activator and pH regulator was sodium hydroxide. Physical characterization showed that the ore has a metallic luster, dark bronze color with greenish stripes, and irregular breakages. Compositional analysis of the crude ore using X-ray fluorescence (XRF) revealed that the ore contains 12.271% CuO, 30.042% Fe₂O₃, 11.475% SiO₂, 32.128% Nb₂O₅, and 3.426% SO₂, along with trace amounts of other minerals, including NiO, WO₃, CaO, and ZrO₂. The liberation size of the ore was determined to be 125 μm, and the Bond work index was found to be 18.81 kWh/tonne and the energy used in comminution was 557.536 kWh. After froth flotation, the resulting froth and depressed samples were dewatered and analyzed using XRF. The highest copper grade of 43.82% CuO was obtained at a mesh size of 63 μm, confirming that this size is optimal for maximizing copper recovery from Anka-Nassarawa ore using froth flotation. The study demonstrates that the most efficient flotation results are achieved by grinding the ore to a 63 size lower than the determined liberation size.

Endang W. Laksono   F. M. Cahyani   Dewi Yuanita   and Isana SYL   

One of the big problems in Indonesia currently is waste management, especially plastic waste. Plastic that comes from food packaging is a source of environmental problems because it is difficult to decompose naturally. Therefore, it is necessary to look for alternative materials to replace petroleum-based plastic packaging, with other materials based on renewable and biodegradable materials. This study aims to determine the properties of cellulose films with the addition of glycerol and lemongrass oil based on the characterization of mechanical tests, water and vapor resistance tests, and functional groups using FTIR-ATR spectrophotometer and the possibility of their use as packaging. Cellulose film was fermented from coconut water and coated sequentially by glycerol (5,10,15 and 20 % w/w) and lemongrass oils. Coating method with lemongrass oil was done for 0, 1, 3, 5, 7, and 14 days. The cellulose film was characterized using tensile strength, water resistance test, water vapor test and FTIR-ATR. The results showed that glycerol and lemongrass oil can affect the physic and mechanic cellulose film. The cellulose film with a concentration of glycerol of 5% and coated by lemongrass oil for 5 days has the best elongation and modulus Young 230.39 MPa. The cellulose film with concentration of glycerol 5% and coated by lemongrass oil for 14 days has the best water vapor resistance and water resistance value of 88.298% and 49.93 respectively and shows an increase in function group intensity of C=O. Thus, the film of cellulose-glycerol-lemongrass is an alternative packaging material.

Arun C Dixit   Harshavardhan B   Ashok B C   and Aravind S L   

Metal matrix composites (MMC) are gaining relevance in many load-bearing applications due to their low density and high stiffness. Compared to traditional monolithic metals, MMC offers exceptional mechanical and tribological properties. Boron carbide is a preferred reinforcement material for MMC due to its lower density, higher hardness, strong refractoriness, and high elastic modulus than other ceramic reinforcements. This paper provides a comprehensive review of the processing, properties, and microstructure of B₄C-reinforced MMCs, emphasizing the potential use of aluminum LM6 alloy as a matrix material. The incorporation of B₄C in aluminum LM6 alloy offers improved strength and stiffness, reduced weight, and increased resistance to wear and fatigue. The review presents a detailed analysis of the properties of B₄C-reinforced aluminum LM6 MMCs, including tensile strength, hardness, wear resistance, and fatigue life, and the importance of the microstructure and interfacial bonding between the reinforcement and matrix. The paper explores current developments and opportunities for the use of B₄C-reinforced aluminum LM6 MMCs in various fatigue-related applications, providing an insight into the future development and opportunities of this class of materials. Need for further research to optimize the processing and properties of these composites is featured.

Mehul Barde   Maria Auad   Joydan Jones   Yongzhe Yan   Na Lu   Selvum Pillay   and Haibin Ning   

Comprised of biopolymer matrix and/or bio-fiber reinforcement, bio-composites are environmentally friendly, lightweight, sustainable, and normally biodegradable. Their unique characteristics have enabled them an alternative material for replacing conventional metallic materials and other composites such as glass fiber reinforced composites. This work is focused on developing and characterizing a novel bio-composite that combines a natural fiber reinforcement with a unique α-resorcylic acid-based epoxy bio-resin. Kenaf fiber mats are impregnated with the epoxy bio-resin and compression molded into a bio-composite. Thermal properties of the bio-composite are characterized with differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Indentation testing in a micro-scale is conducted on the bio-resin matrix and the fiber cross sections. The elastic modulus of the fiber transverse cross section is found to be 7.8 GPa, higher than that of the bio-epoxy resin, 4.3 GPa. Furthermore, the tension performance of the bio-composite is evaluated and compared with that of a conventional epoxy composite with similar kenaf fiber percentage. The bio-epoxy composite has comparable tensile modulus and strength with the conventional epoxy composite. Finally, the fracture surface of the tested samples is characterized using scanning electron microscopy (SEM) and different failure modes, such as fiber fracture, fiber pullout, fiber defibrillation, and matrix fracture, are observed. It is concluded that this novel bio-composite has a great potential to replace conventional epoxy resin based composite for semi-structural applications.

Temitope D. Soneye   Oladipo Olatunji   and Emmanuel Adesanya   

The increasing use of metal oxide materials has met with equal concern as regards associated health risks and environmental transference. NMC-family (LiNi_xCo_yMn_zO₂, where x+y+z=1) energy storage materials are complex transition metal oxides that are being rapidly deployed as replacements to the conventional lithium-ion batteries (LiBs) in the electric vehicle industry. Sustainable catalysis is another area of increasing study since multi-component oxides have a high propensity for cleaving strong chemicals such as the carbon-fluorine bond. NMC materials are mostly synthesized through different thermomechanical processes, with the final composition depending on the required properties in the derived nanostructures. The biological impact of NMC-type materials has been found to be dependent not just on the overall mass, but also on the mass distribution which could be in the form of micro or nanostructures. This study therefore assesses the toxicity effect of NMC-family nanoscale material for energy storage and catalysis, with a view to determining possible safety levels as regards the composition of constituent materials. Preliminary toxicity studies were conducted on inoculated S. oneidensis, B. subtilis and D. magna substrates exposed to NMC materials for time intervals ranging from 0 to 72h and found a direct relationship between the ease of release of Ni and Co ions and cellular respiration and growth. The chemical transformation of NMC nanomaterials was however found to favor an ion release of the order Li > Ni > Co > Mn, although this is an entirely slow process. Altering the configuration of NMC materials through Mn enrichment was also found to significantly reduce its dissolution and could be an important approach to preventing its release into the environment.

Mert Gül   Ayşe Gül Toktaş   Hakan Güleç   Mevlüt Gürbüz   and Aydın Doğan   

In the use of piezocermic applications, piezoceramic compositions have high d₃₃ (>500 pC/N) and Kt (2000) such as PZT-5H. However, these ceramics can be sintered at high temperatures up to 1200˚C). Since these require the use of Ag-Pd inner electrodes with higher Pd ratio, multilayer ceramics are not preferred due to their high costs. In this study, it was aimed to reduce the sintering temperature without dramatically losing the electrical properties of the PZT-5H ceramics with high d₃₃, kp and dielectric constant values. In this context, the PZT-5H composition was modified with different proportions of Li₂CO₃ and sintered for 2-4 hours at different sintering temperatures such as 875˚C-1250˚C depending on the ratio of additions. The piezoelectric and ferroelectric properties of the ceramics were investigated and obtained values were compared with undoped PZT-5H. It was observed that the d₃₃ values of the different amount of Li₂CO₃ added compositions sintered at optimum sintering temperature are close that the composition without additives. In this way, it is predicted that 9/1 Ag/Pd and Ag inner electrode materials can be used in multilayer production and their costs can be reduced.

Mevlüt Gürbüz   and Pınar Uyan   

Dental implants are exposed to cycle loadings and thermal changes. The thermal properties of the materials in dentistry are important in terms of the biological changes that these materials will create in living tissues. The normal temperature of the oral cavity varies between 32-37℃, while eating, it can vary between 0-80℃ with hot-cold foods which led to the trauma and implant deteriorations. Si₃N₄ ceramic is a good candidate to solve these problems due to its inertness, high fracture toughness, strength, high thermal shock resistance and low density. Also, the surface modification of Si₃N₄ is important to enhance the interaction between the implant and bone. In recent years, biodegradable organic biomaterials as CTs (CTs) and silver doped hydroxyapatite (HAPs) combinations have a great attention to improve the Si₃N₄ effectiveness. In this study, MgO, SiO₂, and Y₂O₃ included substrates were fabricated for fast and slow cooling rate during sintering in dental applications. CTs/HAPs fibers were coated with the electrospinning method to develop a modified Si₃N₄ substrate. The crystal structure, microstructure and thermal diffusivity measurement of the substrates and spun surfaces were characterized with XRD, SEM and Laser Flash Method. From the results, the higher density (3.25g/cm³) and thermal conductivity (46.35W/mK) for Si₃N₄ were observed for the fast cooling process during sintering compared with the slow cooling process (3.22g/cm³ and 44.60 W/mK). The hardness and strength of the fast cooled substrate were measured as 1350 HV and 1800 MPa which are greater than the slowly cooled samples (1190 HV, 1670 MPa). CTs /HAPs fibers are homogeneously deposited with electrospinning on the surface of the fast cooled Si₃N₄ substrate to develop the surface functionality. This functionalized substrate can be a candidate in dental applications.

Siddhartha Brahma   Garo Tritrian   Selvum Pillay   Na Lu   and Haibin Ning   

Kenaf based nylon 12 (PA12) composites were successfully made using hydroentanglement and film stack compression molding. The combination of natural fibers with an engineering polymer with a relatively low melting temperature can potentially have high strength and modulus composites. The chopped kenaf fibers were treated in a NaOH solution. The NaOH treatment is used to improve the roughness of the surface and also expose cellulose fibers within the fibers to help improve bonding with the resin. Tensile tests of samples with treated and untreated fibers with a fiber weight fraction of 40% show that the treated fiber composite has an improvement of 13% and 18% in its strength and modulus respectively. The resulting fibers were used to make preforms using hydroentanglement process. The process of hydroentanglement is typically used in making paper products. The use of this process to make composite materials using chopped fibers is a very unique approach adopted for this research. Three different fiber weight fractions were looked at namely 40%, 50% and 60%. Tensile and flexure testing of the samples showed a consistent increase with an increase in the fiber weight fraction. Morphological characterization of the fibers showed that treatment removed excess fluff and dirt and also had striations on the fiber which would lead to better fiber wet-out. SEM images of the fractured surface of the sample with 50% by weight of kenaf fibers showed that there was some fiber bundling as expected leading to dry zones within the composite which could potentially lead to crack initiation. The novelty of the research is developing preforms using chopped natural fibers using hydroentanglement process and the ability to combine these natural fibers with low melting point PA 12 leading to obtaining high strength composite without compromising the structural integrity of the kenaf fibers.

Arka Bandyopadhyay   and Debnarayan Jana   

Recent years have been the platform of discovery of a wide range of materials, like d-wave superconductors, graphene, and topological insulators. These materials do indeed share a fundamental similarity in their low-energy spectra namely the fermionic excitations. There carriers behave as massless Dirac particles rather than conventional fermions that obey the usual Schrodinger Hamiltonian. A surprising aspect of most Dirac materials is that many of their physical properties measured in experiments can be understood at the non-interacting level. In spite of the large effective coupling constant in case of graphene, it has been observed that the interactions do not seem to play a major key role. Controlling the electrons at Dirac nodes in the first Brillouin zone needs the interplay of sublattice symmetry, inversion symmetry and the time-reversal symmetry. In this article, we have used explicit fundamental symmetry to understand the basic features of Dirac materials occurring in three diverse systems in a compact 2 × 2 matrix way. Furthermore, the robustness of the Dirac cones has also been explored from the scientific notion of topological physics. In addition, an elementary introduction on the three dimensional (3D) topological insulators and d wave superconductors will shed light in their respective fields. Furthermore, we have also discussed the way to evaluate the effective mass tensor of the carriers in the two dimensional (2D) Dirac materials. This methodology has also been critically extended to three dimensional (3D) topological insulators and d wave superconductors.

Badis Bendjemil   Jacques G. Noudem   Mohamed Mouyane   Jérôme Bernard   Yannick Guel   and David Houivet   

The purpose of this work is to decrease or eliminate porosities of ETER-VC (Electrothermal Explosion Reaction-Volume Combustion) products with the sintering additives. The Ti–C system has been synthesized for its advantages for refractory, abrasive and structural applications. We attempted to densify TiC by using iron addition; this metal is introduced through a reaction 3TiO₃+Al+C. This mixture reacted exothermically (ϪH₂₉₈ = -1072.7 kJ) and this heat is released according to the Fe addition using the following reaction: 3TiO₃+4����+3��+����→3�վ���+2����₂O₃+xFe. .X-ray diffraction analysis indicated that intermetallic Fe₃Al, TiC and Al₂O₃ are the main phases formed in the reinforced high performance ceramic-matrix composites. The increasing of x wt. % iron decreased the lattice parameter of TiC. Field emission scanning electron microscopy examinations showed that the addition of Fe decreased TiC particle size and changed their growth controlling mechanism. Also, Raman spectroscopy analysis demonstrate that at higher Fe contents, oxygen dissolved in the TiC crystal structure leading to the formation of titanium oxy-carbide with lower lattice parameter and residual un-reacted carbon in the products. The adiabatic temperatures for the reactions containing x wt. % Fe estimated using the thermodynamic data according to Merzhanov criteria. Thus, doping method is finally used to fabricate materials by ETER-VC combustion mode for industrial applications.

G. E. Gebramichael   

In this paper, we have studied the effects of temperature on the free carrier trap of Gallium Sulfide (GaS) in Shockley read hall recombination mechanism. We have seen dependencies on the energy level in the trap of electrons and holes in their respective bands and classify these energy levels into five regions based on the interactions of the localized states with the conduction or valence bands in the high-temperature region. Gallium sulfide compound semiconductor has material impurities that introduce some intermediate energy levels in the forbidden gap. These levels act as recombination centers (or traps, from which the process is otherwise depicted as trap assisted recombination) and an intermediate step is introduced in the recombination process. Another is described as a hole that ascends to the intermediate level (equivalently described as a hole capture of the trap), recombining with an electron. It has also investigated that, at high temperatures, it shows only the electron trap for a wider range of localized trap energies and it shows a small region of localized trap energies for low temperatures. It also shows similar variations for trap density. Additionally, we also analyse the effects of injection levels on traps of free carriers. The variation of both excess carriers in the conduction and valence bands and excess electrons on trap level is the same with illumination at low injection level.

Mert Gul   Mevlüt Gurbuz   Abdi B. Gokceyrek   Aysegül Toktaş   Taner Kavas   and Aydın Dogan   

In this study, lead-free 94Bi_0,5Na_0,5TiO₃-6BaTiO₃ (94NBT-6BT) ceramics were fabricated by solid-state synthesis method at ambient atmosphere. Glassy phase and rounded particles in 94NBT-6BT was observed with increasing Mn content. The effects of doping manganese on the ferroelectric properties of 94NBT-6BT bulk ceramics were evaluated. From the XRD results of the calcined powders, peaks were slightly changed to higher 2 theta value while increasing manganese ratio. Multivalence additive Mn ions act as acceptor dopant in 94NBT-6BT structure at ambient atmosphere. Samples were sintered from 1075 ℃ to 1175 ℃ for 2 hours to obtain highest piezoelectric values. SEM results show that glassy phase and rounded particles in 94NBT-6BT was observed with increasing Mn content so, bulk density was enhanced up to 1125C. From the results, 0.3 wt% manganese doped 94NBT-6BT samples have highest electromechanical coupling factor about 0.23, mechanical coupling factor (Qm) 150 and d₃₃ 110 pC/N respectively. Further work, 94NBT-6BT and Mn-doped 94NBT-6BT multilayer actuators were manufactured by water-based tape casting technique. The active area was 49 mm² MLA and was fabricated by using Ag-Pd internal electrode without Pd-Bi reaction at the electrode-ceramic interface. Hysterisis loop measurements of manufactured lead free actuators were done by using Aixacct CMA module. Remnant polarization values of Mn-doped 94NBT-6BT MLA for a layer were higher than 6 µC/cm².

Andrei Klyndyuk   Ekaterina Chizhova   Irina Matsukevich   and Ekaterina Tugova   

The effect of cationic composition and sintering conditions on the electrotransport and thermoelectric properties of Ca₃Co_xO (x = 3.8, 4.0, and 4.2) had been investigated. It had been found that increase of cobalt oxide content in the samples increase their electrical conductivity, creation of phase inhomogeneity improves their thermo-EMF coefficient, and sintering above temperature of peritectoid decomposition increase their apparent density, which, in the whole, improves thermoelectric properties of ceramics based on the layered calcium cobaltate Ca₃Co₄O. So, power factor values of phase inhomogeneous ceramics Ca₃Co_4.2O, sintered in air below and above temperature of peritectoid decomposition of Ca₃Co₄O, at 800℃ were equal 255 and 273 respectively, which was 2.1 and 2.4 times larger than for the Ca₃Co₄O. It had been also found that sintering of phase inhomogeneous ceramics both in oxidizing or reducing atmospheres resulted in improving of its functional properties. So, power factor values of Ca₃Co_3.8O (sintered in oxygen at 970℃) and Ca₃Co_4.2O (sintered in nitrogen at 920℃) at 800℃ were equal 422 and 378 respectively, which was 3.5 and 3.1 times larger than for the Ca₃Co₄O.

Getu Endale   

This paper presents the effects of the transition energies on photoluminescence intensities in Zinc Oxide compound semiconductor due to the intra-band transition of free carriers. The excitation of free carriers from the valence band to conduction band and from different localized state to the conduction band by the illumination of sufficient energy is considered. A theoretical model for minority carrier trapping is also investigated to explain the dependence of the photoluminescence on the trap energy. Variation of photoluminescence intensities along with localized state energy and transition energy is considered at different temperatures. As temperature increases the photoluminescence due to the transition of free electrons from the conduction band to the valence band, from the conduction band to the localized states and from the localized states to the valence band are increasing.

Fouzia. Abbas   and R. Bensaha   

The present paper reports on the structural and optical properties of undoped and 5% Pb-doped TiO₂ thin films deposited on glass and silicon substrates prepared by the sol-gel technique have been investigated. Dip-coated thin films have been examined at different annealing temperatures (400-500℃). The results shows that Pb-doped TiO₂thin films start to crystallize at low temperature (400℃). The morphology and surface structure of the films were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveals a nanoporous structure of anatase and brookite with particle sizes ranging between 20 nm and 100 nm. Refractive index and porosity were calculated from the measured transmittance spectrum. SE study permits to determine the annealing temperature effect on the optical properties and the optical gap of the Pb-doped TiO₂ thin films. Photoluminescence (PL) spectrum revealed that emission increase with annealing temperature. A slight shift of transmission curves to higher wavelengths is observed for curves of Pb-doped TiO₂ thin films in comparison with those undoped, this was explained by the lowering of the band gap of TiO₂.

E. L. Pankratov   

In this paper we introduce an approach to decrease dimensions of operational amplifier based on field-effect heterotransistors. Dimensions of the elements will be decreased due to manufacture heterostructure with specific structure, doping of required areas of the heterostruc-ture by diffusion or ion implantation and optimization of annealing of dopant and/or radiation defects.

Berhanu Aragie   

We investigate the way of enhancing the optical third order susceptibility, the refractive index, and absorption coefficient of a composite media in which identical nonlinear nanospheres having double interfacial layer randomly embedded in the linear host medium. We observe two maxima peaks of the nonlinear properties. We also show that the effect of double interfacial layers on the third order susceptibility, the refractive index, and absorption coefficient depends on the volume fraction metal/ dielectric nanosphers and the nature of the double interfacial layers. Under appropriate condition (nature of the two interfacial layer) we found two maximum peaks of the nonlinear properties. We also compare with the same composite without interfacial layer and in the presence of single interfacial layer and our finding shows that because of additional interfacial layer the effective medium exhibit a better third-order susceptibility, refractive index, and absorption coefficient.

Huseyin Zengin   Hayrettin Ahlatci   Serafettin Oner   Mustafa Emre Demirkazik   Sait Ozcelik   Yunus Turen   and Yavuz Sun   

Heat treatment is the most commonly used production step which can change the overall mechanical properties of the material without changing the chemical composition. Among the heat treatment methods, accelerated cooling has been regarded as one of the most important method for obtaining good mechanical properties. Today, this method is used in the manufacture of thin pearlitic steel, double phase steel, bainitic steel in the production process of many different quality and size products from construction bar to profile. In the scope of this study, investigations were carried out on S355J2 equal angles section profiles produced by hot rolling method. It was observed that intensive inclusions were found in all of the materials and the mechanical strength could not be met at low rolling ratios. Particularly, these materials with low impact resistance have been subjected to accelerated cooling process in order to increase their impact strength. As a result of the accelerated cooling process, significant increases in impact strength have been observed, particularly with the change of microstructure.

Jayatin   Chandra Liza   and Syuhada   

Starch blending with linear low-density polyethylene (LLDPE) is one of the plastic packaging materials alternative used for solving the plastic waste problem that difficult to degrade. Polymeric materials will change when exposed to weather that releases heat, chemistry, and light. It can be a trigger factor in the degradation process. Xenon Arc accelerated weather simulation test is one way to find out the resistance of plastic materials to weather. This study aimed to explain the effect of xenon arc light on LLDPE-starch-clay composite. In this work accelerated photodegradation tests using Xenon Arc ATLAS Ci 3000+ were carried out on LLDPE-starch-clay composite sample films. Clay, compatibilizers, and starch with a starch content of 10 wt% and 20 wt% were used to make composites masterbatch. The composite masterbatch then extruded with LLDPE and was prepared to make a film sample using Rheomex Haake Blown film. Mechanical properties of the film samples before and after xenon arc accelerated photodegradation treatment were tested using Universal Testing Machine (UTM) Shimadzu AGS-10kNG. The composite sample made from ten wt% starch showed 55% reduction in tensile strength after 14 days of degradation while sample prepared with 20 wt% starches was brittle after seven days of exposure to xenon arc light. Fourier Transform Infra-Red (FTIR) spectrophotometer test result for composite samples made from 10 wt% and 20 wt% starch after exposure to xenon arc light show increasing the intensity at the wave number of 1722 cm-1 that corresponding to carbonyl bond this proved that degradation has occurred.

Muslim Çelebi   Aykut Çanakçi   Serdar Özkaya   and A. Hasan Karabacak   

In this study, ZA27/Al₂O₃ nanocomposites reinforced with 1 vol.% Al₂O₃ nanoparticles were produced using mechanical milling and hot pressing method. The milling time was changed between 1h to 8h. The hot pressing prose was performed in vacuum at 432℃ and pressure of 600 MPa. The effect of milling time on the density, hardness and tensile strength of the ZA27/Al₂O₃ nanocomposites were investigated. The results show that the increase in milling time resulted as a decrease in the density of nanocomposite due to the change in hardness of that. It was observed that the tensile strength of the nanocomposites reached their maximum value (163 MPa) at milling time of 2h and then decreased linearly with increasing milling time. Moreover, the hardness of the nanocomposite milled for 8h was obtained as 155 HB which is about 9 % higher than the hardness of nanocomposite milled for 1h. A linearly increase was also observed the hardness of nanocomposites.

Andrei Klyndyuk   and Ekaterina Chizhova   

The (x = 0.05, 0.10, 0.15) solid solutions have been synthesized by means of solid state reactions method, their crystal structure, microstructure, electrical and dielectric properties within wide interval of temperatures and frequencies have been investigated. It is found that the titanates crystallize in an orthorhombic structure and are p-type semiconductors, which sinterability and dielectric constant increase, but grain size and thermo-EMF coefficients decrease at partial substitution of titanium by niobium and manganese. It is established that ceramics is electrically homogeneous and relaxation processes in it are non-Debye-like, and values of activation energy of relaxation obtained from results of impedance and modulus spectroscopy are in a good agreement.

Tung Son Vinh Nguyen   Tien Minh Huynh   Thien Dien To   Tin Chanh Duc Doan   and Chien Mau Dang   

Silver/silver chloride (Ag/AgCl) is commonly used as a reference electrode in electrochemical measurements. However, commercial macroscopic Ag/AgCl electrodes cannot be used in micro-electrochemical sensors. Thus, many scientists are trying to miniaturize reference electrodes to integrate into one sensor chip. In this paper a new approach for fabrication of Ag/AgCl thin films coated with agarose gel as planar reference electrodes for potentiometric sensors is introduced. A silver thin film of 220-250 nm was sputtered and patterned on silicon dioxide/ silicon substrates by lithography and lift-off techniques. A AgCl layer was coated on the Ag film by using a Ag[NH₃]₂Cl complex at 80℃ in vacuum. The thickness of the AgCl layers was about 5um. The Ag/AgCl layers were then coated with an agarose gel. The AgCl layers were characterized by X-ray diffraction, micro Raman spectroscopy and scanning electron microscopy. The Open Circuit Potential (OCP) measurements with the fabricated electrodes as reference electrodes in pH 7 buffer solutions were performed in comparison with a commercial Ag/AgCl electrode. The potential difference between the fabricated Ag/AgCl electrodes and the commercial Ag/AgCl electrode was insignificant. The coating of the agarose layer as a protection layer of the Ag/AgCl electrodes enhanced the durability of the modified electrodes. The results indicated that the fabricated Ag/AgCl thin films coated with the agarose gel could be used as planar reference electrodes for potentiometric sensors.

Tuba Bahtli   Veysel Murat Bostanci   Derya Yesim Hopa   and Serife Yalcin Yasti   

Thermal shock resistance of MgO-C refractories, which were used in the iron and steel industry, by incorporation of pyrolytic carbon black obtained by waste tire pyrolysis was investigated. The effect of porosity on the thermal shock resistance of those refractories as a function of carbon source (graphite or pyrolytic carbon black) was also examined in the current study. The microstructure and fracture surfaces were characterized using the Scanning Electron Microscopy (SEM). Experimental studies showed that refractories produced by the use of pyrolytic carbon black had higher amount of porosity and lower thermal shock resistance than refractories containing flake graphite.

Milene Muniz Eloy da Costa   Santino Loruan Silvestre de Melo   and Enio Pontes de Deus   

Due to environmental problems and exhaustion related to materials provided from non-renewable sources, the development of recycling technologies using residue as raw material has grown increasingly. Polypropylene (PP), a thermoplastic polymer, despite be easily recycled, presents a decrease in their mechanical properties after reprocessing cycles. In order to solve this problem, reinforcements may be added, producing a composite with better properties. The choosing of the dispersed phase aimed to consider, especially, its mechanical properties. Moreover, it was also considered the orientations of the incorporated fibers at the composite mechanical strength. In this scenario, a composite material of polymer matrix from recycled PP reinforced unidirectionally and bidirectionally with bamboo fibers were prepared. The fibers were treated with modifiers in order to increase the adhesion between polymer/fiber. The results showed that the use of reinforcement improves the mechanical properties of the polymer. Also, the superficial treatments were effective, indicating that there was an increase of the compatibility between the materials. It can be also inferred that the orientation of the fibers has directly influence at the final properties of the composite.

Badis Bendjemil   Mohamed Mouyane   Jacques G. Noudem   Jérôme Bernard   Jean Michel Reboul   Yannick Guel   and David Houivet   

Cubic boron nitrid (cBN) bonded TiC and alloyed with single walled carbon nanotubes (SWCNTs or NC) ceramics matrix nanocomposites (CMNC's) tools were fabricated by a field active sparck plasma sintering process (FASPS). The effects of cBN-TiC ratio, carbon nanotubes and optimization of the sintering process on the microstructure, densification in addition mechanical and vibronic properties of NC-cBN-TiC nanocomposites were studied. The results showed that the nanocomposite cBN-TiC vol. ratio of 8:2 with 0.1 wt% NC. It was found that microhardness increases significantly with addition of NC exhibited the highest microhardness and fracture toughness. After sinters of the samples at 1800℃, 10 mn, 75 MPa of cBN–TiC_1-x with x=0.8 with and without addition of 0.1 wt% NC were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction. The samples exhibited a dense polycrystalline structure, from the resonant Raman scattering we can locate the vibration frequency of the transformation cBN to hexagonal boron nitrid (hBN) and formation of secondary hard phase TiB₂ to consoled the (CMNC's) tools. The final product is hBN_-TiC-TiB_2-NC.The best product contained cBN_x-TiC_1-x (x=0.8)-0.1 wt% NC which was sintered at 1800℃, 75 MPa for 10 mn. The Vickers hardness of cBN_-TiC_1-x (x=0.8) increases with NC incorporation in the matrix The indentation fracture toughness was calculated to be 12.30 MPa m^1/2 for cBNx_-TiC_1-x (x=0.8)-0.1 wt% NC ceramics matrix nanocomposite (CMNC's) tools with excellent wear resistant will be confirmed. The wear of cBN-TiC of the composites tools have shown that this is predominantly a chemical process involving the interaction of the tool with its environment and is restricted by the formation of protective layers on the exposed faces of the tool by the addition of NC. The wear features of tools used in fine cutting tests under identical conditions will be compared and the results will be interpreted in terms of the existing models for the wear of cBN-based nanomaterials by the effects of the additives in the modified tools.

Mahmoud Nabil Helaly   Ahmed Mohamed Alam-Eldein   and Ali Mohamed El-Sheikh   

Aim: Some patients experience adverse reactions to poly (methyl methacrylate)-based (PMMA) dentures. Polyamide (PA) as an alternative to PMMA has, however, not been well documented regarding water sorption and water solubility. The aim of this in vitro study was to evaluate the effect of two different cleansing agents on water sorption and solubility of two different thermoplastic denture base materials. Materials and methods: A total of 60 samples were fabricated from two different thermoplastic denture base materials (i.e. vertex thermosens and breflex). The samples were divided into 3 groups. Each group was including 20 samples, 10 samples from each denture base material. Samples of Group I were subjected to the distilled water as a control group. While samples of Group II were subjected to the Corega as a cleansing agent and samples of Group III were subjected to Fitty dent as the other cleansing agent. Effect of the two cleansing agents on the two-different thermoplastic denture base materials were evaluated and compared with regards water sorption and solubility. Results: Non-significant results were found regarding water sorption and solubility. The fittydent cleansing agent had a slight more non-significant effect on color stability of vertex thermosens and breflex denture base materials than corega cleansing agent and water. The corega and fittydent cleansing agents had a nonsignificant effect on water sorption and solubility of vertex thermosens and breflex denture base materials. Conclusion: Corega and fittydent cleansing agents could be used safely for disinfecting denture base materials (vertex thermosens and breflex) as they had non-significant effect on color stability, water sorbtion and solubility.

Sam Barati Nardin   Javad Rabiee Ezbarami   and Reza Fazeli   

Despite of laminate or sandwich composite materials structure, mechanical behavior can estimate by methods or analytical relations like laminates classical theory according factors just like mechanical properties, fiber percentage, and product methods and etc. but generally these estimates are far from experimental results. This paper investigates about influence of product methods and different cores on buckling and post buckling behaviors of sandwich panels. Each panel was built by to quit different product method, hand layup or vacuum bag infusion procedure with different core. To build the panels an effort had made to choice materials which have usage in marine industry, special for high speed boats. Sandwich panels have 150×450 mm² dimensions and one simply support and one clamed support. After tests, numerical models results which drive from finite element software are compared with experimental data. The results represent that combined model is suitable for simulate buckling and post buckling behavior. After chosen the software model, different parameters were evaluated whom the link element has the most efficacy on numerical results.

Vladimir A. Grachev   Andrey E. Rozen   Yuri P. Perelygin   Sergey Yu. Kireev   and Irina S. Los   

The paper estimates corrosion resistance of new multilayer metal materials with internal protector, in which the principle of tread pitting-protection is implemented. Experimentally, using the electron-microscopic method, the mechanism of corrosion destruction of layers is substantiated. The electrochemical and chemical methods of accelerated tests are proposed, which make it possible to determine the rate of corrosion destruction. The electrochemical method allows revealing the limiting stage of the process, calculating the mass index of corrosion and justifying the choice of the tread for this corrosive environment. The chemical test method makes it possible to quantify the effectiveness of the action of the inner tread and determine the relative index of corrosion resistance of the multilayer material compared with the monometallic material.

Mahmut Can Şenel   Mevlüt Gürbüz   and Erdem Koç   

In this study, graphene nanoplatelets (GNPs) reinforced aluminum (Al) composites with various GNPs content (0.1, 0.3, 0.5wt.%) were fabricated by powder metallurgy (PM) method. In this method, ultrasonication, mixing, filtering, drying, compacting and sintering processes were performed. The crystal structure and microstructure of powders and fabricated composites were analyzed with X-Ray diffractometer (XRD) and scanning electron microscopy (SEM). With this study, the effects of GNPs content were investigated on the density, Vickers hardness, ultimate tensile strength, and microstructure of Al-GNPs composites. The Vickers hardness (57±2.5 HV) and ultimate tensile strength (120MPa) of Al-0.1%GNPs improved up to +90% and +23.3% when compared with pure aluminum (30±2 HV, 92MPa). From the microstructural analysis, homogeneously distributed GNPs was located at aluminum grain boundaries. The mechanical properties of Al-GNPs composite decreased due to the agglomeration of GNPs above 0.1wt.% GNPs content.

Borys M.Gorelov   Oleksiy I. Polovina   Alla M. Gorb   Marek Kostrzewa   and Adam Ingram   

Impact of nanosized oxide particles of titania (rutile) (TiO₂) and silica-titania fumed compound on physical properties related to inner structure of a styrene-cross-linked polyester resin have been experimentally studied. The IR-spectroscopy and the positron annihilation lifetime spectroscopy (PAL) were used to study the electronic polarizability of interatomic bonds and the positron annihilation processes with increasing the filler loading. All the nanocomposites show unmonotonous variations in the IR-absorption lines and the positron annihilation parameters. Three lifetime components, namely τ₁, τ₂, and τ₃ with intensities I₁, I₂, and I₃ have been determined. The lifetime loading dependences exhibit non-monotonous lowering within the low loading range (C_m ≤ 5%) with the minima values at C_m ~ 1.5 % for the unfilled resin and the nanocomposites. The free-volume portion f_v (in %) in a polymer matrix decreases droningly for the nanocomposites with STO-particles upon loading while for the TiO₂-nanocomposites it increases non-monotonously. The parameters describing the supramolecular structure of the nanocomposites have been calculated using the fractal approach. Some correlations between loading-dependent PAL-properties and underlying alterations in the resin's supramolecular structure have been discussed.

Cengiz Görkem Dengiz   Mahmut Can Şenel   Kemal Yıldızlı   and Erdem Koç   

Scissor-type systems are frequently used as lifting systems in the industry. These systems are mainly preferred to do maintenance, repair, and clean. In this study, the design and analysis of a scissor lift system were performed with having a load carrying capacity of 500kg and a working height of 2m. The solid model and assembly of the system have been developed by the SolidWorks program. The structural analysis of the system was also investigated with the help of the same program i.e. stress, deflection, and safety factor values of system elements were obtained. As a result of the analyses, it was concluded that the system designed could safely be used during load/unload operations.

Rashed Al Mizan   and Md. Aminul Islam   

Emerging thermal dissipation of many electronic devices, i.e. light emitting diodes, energy storage components, CPU chips etc. as well as in many emergent new applications (smart textile, self-assembling materials, etc.) is a great challenge. The reliance of thermal conductivity of composites on the filler loading, filler networking morphology and on the whole composite structure is also discussed. This work is intended to design composites for the improvement of thermal conductivity of polypropylene and ethylene-vinyl acetate copolymer with lower filler contents. As filler both organic (activated carbon) and inorganic (alumina) materials alone or in a combination of various relative proportions have been used. An internal blending unit was used for melting the copolymer and proper mixing the filler particles with the molten matrix. Final composites were made by the hot press. Then Lee's Disc apparatus was used to measure the thermal conductivity of various composite samples by steady-state method. Experimental results show that only carbon black addition was not adequate to increase the thermal conductivity of the composites to expected level. The experimental value compare with some theoretical model to describe the prediction value accuracy for such multiphase composite. However, addition of small amount of alumina powder with carbon black significantly increased the copolymer composites.

Pınar Uyan   and Servet Turan   

As a result of the studies that have been made for increasing the thermal conductivity of Si₃N₄, increasing thermal conductivity values have paved the way for the technologic applications such as using the Si₃N₄ in electronic devices as heatsink and substrate. Two important parameters such as density and grain boundary phase that affect the thermal conductivity of the Si₃N₄ ceramics are based on the sintering additives and techniques. Exposure time to gas applied in the sintering and cooling cycle after sintering are the critical factors that affect the intergranular phase crystallization. In this study, the effect of Y₂O₃ doped Si₃N₄ ceramics and different cooling cycle after gas-pressure sintering to the phase crystallization and thermal diffusivity was researched. The samples were subjected to two different cooling cycles after sintering. The thermal diffusivity value of the sample applied by slow cooling cycle is 17.79 mm²/sec, the sample applied by rapid cooling cycle is 16.2 mm²/sec. As a result of slow cooling cycle, the crystallization has increased but thermal diffusivity has decreased at the rate of ~ 8.94%.

Pınar Uyan   and Remzi Gürler   

Nowadays, light part production by the strategies of performance improving known as 'Engine Downsizing' by decreasing the engine size is popular. Al-Zn-Mg alloyed composites reinforced by SiC particle are mostly produced by powder metallurgy. In fact, Liquid mixing casting technique alternatively developed against the powder metallurgy has more than advantageous when taking into the consideration of its production capacity, production cost and part production similar to the definitive form. In this study, the hardness variation of SiC particle reinforced composites manufactured by the method of affordable 'Vortex Casting' and in different amounts by weight and 7075 alloy after aging process in different times at 140℃ and 230℃ was reviewed and their microstructure analyses were made accordingly. After 16 hours aging of 7075 alloy and the composites reinforced by 5% SiC at 140℃ and 12 hours aging in the composites reinforced by 3% SiC, at 230℃, after 9 hours aging in all materials, the maximum hardness value was measured. In higher aging temperature, due to the fact that max hardness was achieved in shorter period, in lower aging temperature, higher hardness was achieved.

Dirick Von Behr   

The proposed amendment of the German regulation for the treatment of tannery wastewaters (ATV-DVWK-M774-proposal 2015) emphasizes minimization of the pollution burden before treatment (inflow) [1]. Current regulations are directed towards setting limits to what may leave an ETP (outflow). The new provisions, on the other hand, demand that a verifiable reduction of the polluting load is realized before the water enters the treatment system. An absolute decrease at the level of individual components requires the measurement of these components for a starting point. This paper discusses the ways of expressing the exhaustion of a selection of fatliquors on chrome and chrome-free leathers. Each product has a specific affinity to the tanned hide and an individual environmental imprint. This specificity can be used for targeted reduction of the inflowing pollution burden. The findings of the study can act as a starting point for setting up an own methodology and a detailed level of reporting for all who need to understand a fatliquor's true affinity towards the leather and those who endeavor to minimize the environmental impact of their processing.

Fadhel Abbas Abdullah   and Zahra khalid Hamdan   

This study aims to explain the effect of high strain rate torsion on unidirectional fiber glass / epoxy composite with and without adding nano particles (carbon and alumina) with weight percentage 2% and study the effect of the temperature and humidity on the samples under torsion dynamic test. Using the torsional Hopkinson split bar to testing under angle of the twist θ=10°. It can noticed that the maximum of the shear (stress, strain) of the composite increased with adding nano particles by rate of (24.8%, 3.2%) with added 2% nano carbon and (26%, 8.5%) with added 2% nano alumina, where the shear stress, shear strain and shear strain rate of all samples decreased with increasing (temperature and humidity) with different percentages. Finally, it was modifying Johnson-Cook constitutive model by adding parameter represented the humidity effect to simulate the experimental results, and then it was found the error percentages between the experimental results and theoretical results which range (0.0044% and 15.5%).

Azaryan, N.S.   Batouritski, M.A.   Budagov, Yu.A.   Demyanov, S.E.   Karpovich, V.V.   Liubetski, N.V.   Maximov, S.I.   Rodionova, V.N.   and Shirkov, G.D.   

Presented the ideas and techniques underlying the measuring workbench created within the framework of a Dubna-Minsk research project to estimate, by measuring of S¹¹, of a high value (about 10¹¹) of Q-factor of a 1.3 GHz superconducting radio-frequency (SRF) niobium cavity of TESLA-type, which is a key element the superconducting accelerating system of the International Linear Collider (ILC) operating at 1.3 GHz and made of thousands of such cavities. In the paper, the results of measurements and Q-factor estimates are also presented and discussed.

I. Buljeta   Z. Zovko Brodarac   A. Beroš   and M. Zeko   

The phenomena defects in the triple junction grain boundaries affect the properties of the microstructure of aluminum alloys. For that purpose the microstructure of the alloy EN AW 6060 on the billet sample cast by DC (Direct Chill) technology was analysed in order to gain insight into the origin and form pores in the final stages of solidification. Mechanisms of solidification shrinkage, thermal contraction and low permeability of interdendritic channels networks were discussed in moment when melt becomes isolated in separate locations forming new structure. Under such conditions, the tensile stress caused by anisotropic thermal contraction of a coherent dendrites network, causing the formation of pores in the corners of the grain boundaries whose morphology is determined by SEM / EDS analysis.

Mahmut Can Şenel   Mevlüt Gürbüz   and Erdem Koç   

In this study, Si₃N₄ (varying from 0 to 12wt.%) or SiC (varying from 0 to 30wt.%) reinforced aluminum matrix composites were fabricated by powder metallurgy method. The effects of reinforcement element (SiC or Si₃N₄) addition on the mechanical properties of aluminum composites were newly examined for large-scale distribution. Microstructures and crystal structures of composites were analyzed via scanning electron microscope (SEM) and X-ray diffractometry (XRD), respectively. Density, hardness and compressive strength of composites were tested by density meter, micro Vickers hardness tester and universal test machine. From the experimental results, it was observed that the hardness value of pure aluminum was obtained 30 HV. Also, the highest hardness values were obtained at Al-9%Si₃N₄ (57 HV) and Al-30%SiC (79 HV) composite. Similarly, the highest yield and ultimate compressive strength were determined at Al-30%SiC and Al-9%Si₃N₄ composite. Pure Al, Al-30%SiC and Al-9%Si₃N₄ were measured as 82, 138, 198 MPa and 113, 224, 292 MPa, respectively. Increased to weight percentage of Si₃N₄ from 9% to 12% in Al-Si₃N₄ composites, the apparent density, Vickers hardness and compressive strength of Al-12 wt.%Si₃N₄ composite sharply decreased due to the agglomeration of Si₃N₄. As a result, it has been observed that SiC or Si₃N₄ addition makes a positive contribution to the mechanical and microstructure of aluminum composites. These composites should be used for the wear application of aluminum.

Andrei Klyndyuk   Ekaterina Chizhova   and Natalie Krasutskaya   

Using solid-state reactions method the ceramic samples of (Bi,Pb)₂Ba₂(Co,M)₂O_y, (Bi,Pb)₂Sr₂(Co,M)_1.8O_y, and (Bi,Pb)₂Ca₂(Co,M)_1.7O_y(M = Mn, Zn) solid solutions had been prepared, their lattice constants had been determined and their thermal expansion, electrical conductivity and thermo-EMF had been measured, and their power factor had been calculated. Effect of the bismuth substitution by lead and cobalt substitution by manganese and zinc in the layered cobaltates of bismuth and alkaline-earth metals (AEM) on the crystal structure and physicochemical and functional properties of their derivatives was analyzed. It was found that cobaltates studied are p-type conductors, which linear thermal expansion coefficient (LTEC) values varied within (9.68-13.2)•10^-6 K^-1. Power factor values for the samples studied unmonotonously changed when temperature increased and at 1000 K were maximal for Bi₂Ba₂Co₂O_y, Bi₂Sr₂Co_1.7Mn_0.1O_y, and Bi₂Ca₂Co_1.7O_y compounds - 12.1, 10.1, and 10.6μW/(m•K²) respectively.

Nikhil Rastogi   Narender Singh   and Sandeep Saxena   

GPVDM is simulation software that is used to analyze the optical and electrical properties of organic solar cell, based on P3HT: PCBM organic materials. The bulk hetero junction organic solar cell has been electrically simulated by GPVDM software at different series resistances. Organic bulk hetero junction solar cell is a mixture of P3HT and PCBM used as active layer material, ITO; a transparent electrode, PEDOT: PSS; an electron blocking layer and Al, back electrode. In this analysis, the electrical simulation has been done at different series resistances. It is observed that current density-voltage (J-V) characteristics are varied with the series resistance. The best J-V characteristic as well as maximum short circuit current is obtained at 1Ω series resistance.

Reza Faiez   and Yazdan Rezaei   

A numerical study was carried out to describe the effect of the melt hydrodynamics on the crystallization front shape in the Czochralski growth of a semitransparent oxide crystal. In the present model calculation, the enthalpy-porosity method was used to solve the phase change problem with the convection due to buoyant, thermocapillary and centrifugal forces. It was shown that the rotationally-driven flow protrudes into the mushy zone when the crystal rotation rate was increased to a certain critical value corresponding to Gr/Re²=0.89 as the ratio between the intensity of buoyancy and forced convection flow in the melt. The ratio between the vertical and horizontal temperature gradients beneath the mushy zone was found to be decreased by increasing the crystal rotation rate. It was shown that the shape of the zone deforms abruptly when the ratio between the axial and radial temperature gradients decreased to the values smaller than the unity. The Burger's number condition was found to be violated in the case Gr/Re²<0.89, at which the onset of geostrophic instability is expected.

F.O. Kolawole   O.M. Olugbemi   S.K. Kolawole   A.F. Owa   and E.S. Ajayi   

Modern day building materials must be sustainable, cheap, environmental friendly, durable and available. Laterite reinforced with bamboo fiber was moulded into blocks to determine the compressive strength, flexural strength and fracture toughness using universal tensile machine (UTM), while the elemental composition was determined by EDS, SEM/Gwyddion software were used to study the fractured surface of the bamboo-fiber reinforced laterite (BFRL) block. Water absorption test and bulk density were also carried out. The blocks were moulded by varying the percent weight (%wt) fraction of bamboo fiber from 0 to 25%. The dimensions for the compressive and flexural samples were 100 x 100 x 100 mm and 600 x 100 x 100 mm respectively. The results of the experiment showed that at 25 %wt of bamboo fiber a maximum compressive strength, flexural strength and fracture toughness of 5.0±0.25 MPa, 2.25±0.113 MPa and 1.70±0.085 MPa respectively were obtained. EDS result reviewed the following elements Al, Si, Ca, Fe and C. SEM images analyzed using Gwyddion software reviewed different fracture patterns.

Hiroaki Onoda   and Kohei Sasaki   

Calcium phosphate is an important material used in ion exchangers and adsorbents. In this work, calcium hydrogen phosphate dihydrate, , was prepared from calcium nitrate solution and phosphoric acid. This phosphate transformed to calcium hydrogen phosphate un-hydrate, CaHPO₄, by heating at 200℃, and calcium pyrophosphate, Ca₂ P₂ O₇, by heating at 400 and 700℃. These calcium phosphates were used to remove trivalent iron cation, Fe³⁺ in solution. Samples without heating and those heated at 200℃ indicated a high iron removal ratio. By the addition of these calcium phosphates and stirring for 5 minutes, a high ratio of iron cation was removed from the solution. This removal depended not only on the substitution of calcium to iron, but also on the precipitation of iron hydroxide. Calcium phosphates were also used to remove copper and nickel cations, Cu²⁺ and Ni²⁺. The removal ratios of copper and nickel cations were lower than those of iron cation.

Kongjin Zhou   Qinglin Zhao   and Yulin Zhang   

For the purpose of broadening the scope of applications of nickel slag, this paper focuses on the crystallization properties of glass ceramics with large amounts of iron-rich nickel slag. In this research, the properties including activation energy of crystallization, crystalline growth pattern, main crystalline phase and micro structure were discussed. It was shown that when KNO₃ was added, the Fe²⁺ oxidized to Fe³⁺, the activation energy of crystallization increased from 283.70 kJ/mol to 345.45 kJ/mol and the Avrami changed from 2.40 to 2.35. The main crystalline phase for both samples was pyroxene and it grew in one-dimension.

Badis Bendjemil   Jacques G. Noudem   Mohamed Mouyane   Jérôme Bernard   Jean Michel Reboul   Yannick Guhel   and David Houivet   

Nanocomposites are wear resistant materials used in cutting toAbstract Nanocomposites are wear resistant materials used in cutting tool applications. The materials are composed of ultrafine powder hard phase grains surrounded by a tough binder phase carbon nanotubes (Mo₂C)_1-x(TiC)_x (2≤x≤4)//1Wt% SWCNTs. Composite bicarbide Mo₂C-TiC was rapidly synthesised and simultaneously consolidated by Field activated sintering technique (spark plasma sintering) at which the extensive volume expansion occurred as a function of the volumic fraction from 20 to 40 vol.% of TiC powders and 1 Wt.% of SWCNTs as reinforcement of the CMNC’s. The sintered powder mixture was examined by XRD patterns, the morphology of the obtained phase was observed by SEM and the phase compositions in different regions were analyzed by EDX. The composites were processed using Field Activated Sintering Technique, spark plasma sintering (SPS) at temperatures in the range of 1700-1800℃ with addicting of SWCNTs. The effects of SWCNTs addition on phases morphology, microstructure hardness and fracture toughness of the nanocomposite were investigated. The best product contained 1.0 Wt.% SWCNTs from (Mo_21-xx0.8T_0.2/ 1 Wt% SWCNTs exhibit a better density, highest hardness and a good ductility. Relative densification was achieved 99.5 % from the theoretical and a good mechanical properties like hardness and fracture toughness (K_IC =5.6 Mpa m^1/2) are enhanced. The results were confirmed using Raman spectroscopy.ol applications. The materials are composed of ultrafine powder hard phase grains surrounded by a tough binder phase carbon nanotubes (Mo₂C)_{1_x}–(�վ���)_x (2≤x≤4)//1Wt% SWCNTs. Composite bicarbide Mo₂C-TiC was rapidly synthesised and simultaneously consolidated by Field activated sintering technique (spark plasma sintering) at which the extensive volume expansion occurred as a function of the volumic fraction from 20 to 40 vol.% of TiC powders and 1 Wt% of SWCNTs as reinforcement of the NCMC's. The sintered powder mixture was examined by XRD patterns, the morphology of the obtained phase was observed by SEM and the phase compositions in different regions were analyzed by EDX. The composites were processed using Field Activated Sintering Technique, spark plasma sintering (SPS) at temperatures in the range of 1700-1800℃ with addicting of SWCNTs. The effects of SWCNTs addition on phases morphology, microstructure hardness and fracture toughness of the nanocomposite were investigated. The best product contained 1.0 Wt% SWCNTs from (Mo₂C)_{1_x}–(�վ���)_x, x= 0.2 which was sintered at 1700 ℃ , 70 MPa for 10 min, M_0.8T_0.2/ 1 Wt% SWCNTs exhibit a better density, highest hardness and a good ductility. Relative densification was achieved 99.5 % from the theoretical and a good mechanical properties like hardness and fracture toughness (K_IC=5.6 Mpa m^1/2) are enhanced. The results were confirmed using Raman spectroscopy.

Luisa E. Silva-De Hoyos   Victor Sánchez-Mendieta   Alfredo R. Vilchis-Nestor   and Miguel A. Camacho-López   

Silver nanoparticles (Ag-NPs) were bio-synthesized using Camellia sinensis (green tea) aqueous extract. Nanoparticles prepared with 10^-3M AgNO₃ solution, using 3mL of green tea extract and at 60℃, have spherical shape with a mean diameter of 7nm. The formation of the nanoparticles was confirmed by UV-Vis spectrophotometry through studies of the surface plasmon resonance (SPR). The morphology, size and crystalline structure of the Ag-NPs were determined using high definition transmission electron microscopy (TEM). Moreover, these green synthesized Ag-NPs were found to exhibit good sensing properties towards Cu²⁺ and Pb²⁺ ions in aqueous solutions. This metal ions-sensing ability of the biogenic Ag-NPs was monitored by UV-Vis spectrophotometry (SPR analyses) and fluorescence spectroscopy.

Matthieu Thomassey   Baptiste Paul Revol   Frédéric Ruch   Julia Schell   and Michel Bouquey   

Until today, thermosetting polymer based composites were predominant, but are faced with environmental rules more stringent (COV, recyclability...). Thermoplastic composites are a good answer to the evolution of environmental rules, and have an increased need due to their improved properties compared to thermosets. One thermoplastic process route offered is the injection of monomers with a low viscosity (around 10mPa.s): Thermoplastic-Resin Transfer Molding (T-RTM). Currently, reactive thermoplastics are not technically matured for industrial applications. Indeed, their chemistry and rheology especially in the presence of fibers are not well studied and understood. The reaction time is the most crucial parameter for a well-controlled injection and the viscosity should stay low until full impregnation is achieved. The other point is the reaction kinetics. The faster the reaction, the more reaction heat is released in less time which results in overheating in the center of very thick parts. In a first approach the pure polymer is investigated. To better understand the reaction time during an injection process, rheological measurements were achieved at different shear rates and temperatures. In parallel, the reaction kinetics through the exothermic reaction during polymerization are modelled and experimentally verified.

I. Duretek   and C. Holzer   

The powder injection molding (PIM) process is a cost efficient and important net-shape manufacturing process that is not completely understood. For the application of simulation programs for the powder injection molding process, apart from suitable physical models, exact material data and in particular knowledge of the flow behavior are essential in order to get precise numerical results. In this work, the flow behavior of a 316L stainless steel feedstock for powder injection molding was investigated. Additionally, the influence of pre-shearing on the flow behavior of PIM-feedstocks under practical conditions was examined and evaluated by a special PIM injection molding machine rheometer. In order to have a better understanding of key factors of PIM during the injection step, 3D non-isothermal numerical simulations were conducted with a commercial injection molding simulation software using experimental feedstock properties. The simulation results were compared with the experimental results. The mold filling studies amply illustrate the effect of mold temperature on the filling behavior during the mold filling stage. Moreover, the rheological measurements showed that at low shear rates no zero shear viscosity was observed, but instead the viscosity further increased strongly. This flow behavior could be described with the Cross-WLF approach with Herschel-Bulkley extension very well.

Sarbjit Singh   

Materials, manufacturing and marketing departments are the three major operating subsystems of any organization whether it is a production house or a service center, i.e. neither the goods producing organization nor the service providing organizations works without inventory, they have to maintain some inventory for smooth running of their businesses. In recent years, the study of inventory management has gained importance and lot of work has been done in the field of inventory management. This study provides insights to major work done on the various factors affecting inventory management.

Detlef Wilke   

Lead and tin glazed pottery is frequently contaminated with Pb abundances even on the non-glazed surfaces of vessels and fragments. Elevated lead concentrations result in Pb specific matrix absorption and spectral interference effects on several discriminative trace elements - Ga, Rb and Y - which are important for fully non-destructive micro-chemical provenance based on portable x-ray fluorescence (pXRF) analysis. Empirical Lachance-Traill type correction algorithms have been developed by simulating increasing Pb surface abundances on fired clay samples with lead acetate sprayed on 4.0 µm polypropylene film. For paste surface layers with up to approximately 1 % w/w elemental lead concentrations, full compensation could be achieved, as demonstrated for a representative production waster assemblage of early modern lead glazed slip ware (Weser ware). Since the number of discriminative minor and trace elements in portable and stationary XRF of pottery is at the limit, the development of robust empirical correction algorithms for lead based matrix effects and spectral interferences and the validation of the applied quantification software, respectively, is essential.

Marc Schiry   Christian Lamberti   Peter Böhm   and Peter Plapper   

A novel laser joining process for hybrid polymer-metal structures has proven a strong bond between polyamide and aluminium. This welding technique is strongly requested by the automobile producing industry for numerous applications within structure components. However, the joining quality exhibits a strong dependency on process-related variables, which highlights the need for an online inspection technique. The requirements for a chosen inspection technique are [1], [2]: 1. Showing the results on-line during the joining process; 2. Working non-destructive; 3. Working as an integral method; Being able to determine weld defects. In that case only the Acoustic Emission Analysis (AEA) as a Non-Destructive-Technique (NDT) can be used to guarantee reasonable results. During the first tests at the welding laboratory at the Laser Technology Competence Centre (LTCC) at the University of Luxembourg, AEA sensors are applied onto the surface of the test specimen which has to be welded. In this principle acoustic events, caused by welding defects, are recorded during the laser joining. The most important laser process parameters, like velocity, power and horizontal focal position of the laser spot, have been verified and evaluated by the AEA. It was observed that insufficient laser power can lead to the break of the melting bath, which is often not recognizable by non-destructive optical methods [2]. The AEA however was able to detect this lack of fusion. Using high laser power, the appearance of gas bubbles arising from the Polyamide 6.6 could be detected afterwards in a microscopic micrograph. The AEA signals related to this effect can be correlated clearly. Due to the high pressure of the gas bubbles, the aluminium weld is often interrupted, which can be traced back to the solidification of the aluminium molten mass. Due to the actual situation, the AEA is a well-working NDT online monitoring method and can be used for the correlation of acoustic events and welding defects within the mentioned joining method. Future tasks will develop some algorithms to separate the different defects by pattern recognition of the AEA signals and parameter

E.I. Zhmurikov   

A lot of researchers analyzed reasons for the destruction of the reactor graphite under intense flux of radiation and high temperatures. However, typically, this analysis does not go beyond operating temperatures of graphite reactors that is as usually 800℃ about. In this paper we consider the possibility to predict the life-time of reactor graphite at high temperatures (~2000℃) in principle. Presently appears that the major parameters that affect to the graphite lifetime are the temperature and heating time. High temperature tests were conducted to simulate the heating under the influence of a beam of heavy particles by passing through the sample pulse or AC to study laws of the destruction of a graphite target. Tests carried out in this work have shown the ability to forecast the stability and durability of graphite materials that traditionally used in nuclear engineering at high temperature conditions.

H.Yu Mykhailova   M.M. Nishchenko   B.V. Kovalchuk   V.S. Mikhalenkov   and V.Yu Koda   

The specific electrical conductivity (σ) of mechanical mixture consisting of particles LaNi₅ and multi-walled carbon nanotubes was studied under compression. Founded that the conductivity of mechanical mixture with micro particles LaNi₅ (diameter 28 ± 6 mkm) and 51 wt. % CNT is executed to the order of magnitude σ of CNT. Growth mechanism of specific electrical conductivity of mechanical mixture LaNi₅ with CNTs is due the process of ordering and the transfer electrons from the metal to CNTs. At this concentration, the mechanism of electron transfer from the metal particles to the CNT is most optimal.

Ladarat Kanlayavisut   Pitchanunt Chaiyo   Ki-Seok An   Supon Sumran   and Supakorn Pukird   

Nanowires composite materials were synthesized from rice husk ash using by two metallothermic processes. The rice husk ash and carbon charcoal were mixed with Mg and Sn metals by various ratios and heated at 700℃ and 1000℃ under atmosphere of nitrogen gas. The formed products were studied by scanning electron microscope (SEM) and X-rays diffraction (XRD) technique. SEM images showed the structures of nanowires composite materials with diameter around 50-300 nm and length of more a few 10 μm. XRD patterns indicated the crystal structures of composite materials consisting of Si, MgO, Mg₂SiO₄ phase and SiC, SnO₂ phase.

Jyun-Cing Cao   Tze-Wei Chang   Chun-Yen Chiang   Jaine-Huai Huang   and Tzer-Shin Sheu   

Bulk calcium phosphate biomaterials without sintering were synthesized at room temperature by infiltrating various orthophosphate aqueous solutions into a porous Ca(OH)₂ green powder compact. These orthophosphate aqueous solutions were prepared from a different ratio of Ca(OH)₂/H₃PO₄ up to pH=12. The infiltrated specimens did not show any shape or dimension changes at a lower concentration of H₃PO₄ or a liquid with pH>2. When the liquid contained some supersaturated solids or precipitates, the infiltrated specimens showed their reacted phases at the surface similar to these supersaturated precipitates, which were Ca(H₂PO₄)₂∙H₂O (MCPM), CaHPO₄∙2��₂O (DCPD), or Ca₁₀ (PO₄)₆ (OH)₂ (HA) as pH was increasing. Under a liquid infiltration with a lower concentration of H₃PO₄ liquid, a functional graded calcium orthophosphate composite was observed. Furthermore, relationships among processing factors like pH plus impurities and liquid concentration, phase formation, and microstructure of infiltrated specimens were discussed in detail.

M. J. Suriani   Aidy Ali   A. Khalina   S. M. Sapuan   and Haftirman   

In this study, fatigue life of natural fiber reinforced composite materials was predicted due to manufacturing defects fatigue damage modes. Kenaf bast fibers were used to fabricate natural fiber composite materials with epoxy as a binding material. The Kenaf fiber reinforced composites were manufactured using a hand lay-up process. The defects in Kenaf reinforced composite materials were determined by a non-destructive technique using Infrared (IR) thermal imager. The thermography analyses were verified by optical microscope and scanning electron microscope (SEM) investigations. Then, the Mathematical model for estimating fatigue life by IR thermal imaging technique based on damage accumulation model is proposed. This proposed model is named as S-IR thermal imaging fatigue life model. Determinations of fatigue damage has been predicted and it found that it damage has been fixed with the predicting results. S-IR model proposed that 60% kenaf epoxy with thickness 0.3 cm is recommended as the best formulation to fabricate the specimens due to a longer fatigue life recorded and the result obtained from the fatigue cyclic tension test shows that 60% kenaf epoxy with thickness 0.3 cm had the highest fatigue resistance as indicated by a highest range of stress level, 119.71-53.20 MPa.

Masahiro Ohkawa   and Akito Takasaki   

The deep drawing of an AZ31 magnesium alloy sheet with a commonly used metal mold by three kinds of drawing motions (crank, vibration, and step-by-step motion) was performed, and the effect of drawing motions on the forming performances of the alloy sheet was investigated. For all the forming motions, the limited drawing ratio (LDR) reached was 1.25, and crack formation was limited at the flange part with the rolling direction. The vibration motion, which has a bigger shoulder region, cause greater lattice distortion of the side wall than other motions and the lattice strain for vibration motion increased from the bottom to the side wall of the sheet after drawing, whereas the heteromorphic histories for other motions were different. The crystallite size was largest at the bottom of the sheet for all the forming motions. However, it decreased at the shoulder part of the sheet and also at the side wall. The crystalline grains structure was not affected by drawing motions. It was found that the drawing motions affected the state of stress-relaxation after drawing.

Andrew E. Stetsko   

Retrieved surface layer, which is fine-dyspersated carbide composite structure area which has a higher microhardness and sufficient ductility. It is used for parts that are in friction pairs under conditions of dynamic loads. Some parts that require high resource work, reinforcing coating applied to high thickness – 300 µm. Such details can be processed several times during their gradual deterioration. Work surface heavily loaded parts operating at high unit pressures are applied coating reinforced, composite zone, there is a high content of chromium carbides and large microhardness. The presence of Ni content in the homogeneous zone positively influences the work of such details.

Han Chien LIN   and Ying-Pin Huang   

Pyrolysis of agricultural/forestry processed wastes (AFPW) is one approach that has been investigated to develop materials into products of higher value. This paper describes a concept of multi-utilization with pyrolysis under various conditions which has been extensively prepared for related bio-functional materials like biochar, charcoal and activated carbon (AC). The prepared materials were developed into products such as biochar as part of cultural media for agricultural production; charcoal or AC as a potential moisture-proof adsorbent for food use; and the AC as a kind of liquid absorption for water purification. The biochar was prepared from AFPW as a cultural media substrate. Cultural media with biochar can be applied to vegetable plug seedlings with functions including preserving moisture and fertility, offering oxygen to expand the roots. For a food moisture-proof adsorbent, bamboo and wood charcoals were refined into various ACs using physical activations. The hygroscopicity of the resulting AC was better than that of charcoals, and the water activity of the AC was from 0.45 to 0.46. In addition, water purifying AC used sorghum distillery residue with the method of physics activation with steam-activation, which meets the quality standard for drinking water in Taiwan. The above products are concerned with multi-utilization under various pyrolysis conditions which can be used as a reference for resource reutilization from AFPW and also as examples of bio-functional materials' ability to be implemented in a sustainable reuse of resources.

Yuka Takemura   Masanori Kikuchi   Masamoto Tafu   Takeshi Toshima   and Tetsuji Chohji   

Dicalcium phosphate dihydrate (DCPD) reacts with fluoride ion in an aqueous solution and forms stable fluoroapatite (FAp). This reaction requires a lag time to form nano-sized precursor, hydroxyapatite (HAp)-like calcium phosphate, on DCPD surface. This long lag time prevents DCPD from applying as an effective fluoride removal agent from waste water. The purpose of this study is to improve the reactivity of DCPD with fluoride ion by HAp-coating on the DCPD surface by soaking it in the simulated body fluid (SBF) under various DCPD/SBF ratios and soaking periods. The results showed the HAp-coating on DCPD by soaking in the SBF reduced the lag time to be negligible with increasing in amount of HAp up to 2 % in mass to the DCPD; however, further HAp formation had no affects on improvement of the reactivity.

Franz-Georg Simon   and Olaf Holm   

In 2011, the German Association of Engineers (VDI) started working on a set of guidelines dealing with the improvement of resource efficiency. These guidelines represent a framework that defines resource efficiency and outlines proposals for the producing industry. A special guideline for small and medium-sized enterprises (SMEs) is included as well as guidelines on methodologies for evaluating resource use indicators, such as the cumulative raw material demand of products and production systems. The work on resource use indicators is still in progress. The evaluation of raw materials expenditure will include water, soil and land use. The model will include the availability of raw materials (criticality). Improving resource efficiency at the end-of-life stage is illustrated in this paper by the example of materials recovery from waste, here from residues out of municipal solid waste incineration (MSWI). With mechanical treatment valuable materials like ferrous and non-ferrous metals and secondary construction material can be extracted from MSWI bottom ash. The potential contribution on the resource efficiency is discussed.

L. Mariscal-Becerra.   S. Carmona-Téllez   R. Vázquez-Arreguín   C. M. García-Rosas   C. Falcony   H. Murrieta S.   and M.A. Sánchez-Alejo   

Different emission intensities presented in aluminum oxide phosphors corresponding to different concentrations of doping performed with terbium are analyzed. The phosphors were synthesized by the evaporation technique and were characterized by photo and cathodoluminescence, x-ray diffraction, and EDS techniques for different incorporation percentages of terbium as dopant; they show characteristic transitions in 494, 543, 587 and 622nm, corresponding to ⁵D₄ → ⁷F₆, ⁵D₄ → ⁷F₅, ⁵D₄ → ⁷F₄ and ⁵D₄ → ⁷F₃, respectively when they are excited with λ_exc= 380 nm wavelength at room temperature. The results of XRD show the presence of α-Al₂O₃ phases with peaks located at 2Θ = 25.78, 35.34, 37.96, 43.56, 45.8, 52.74, 57.7, 61.5, 66.74, 68.44, 77.12 and 80.94, and the δ-Al₂O₃ phase 2Θ = 32.82, 45.8, 61.36 and 66.74. These compounds were heat treated for two hours at 1100℃. EDS analyzes indicate that these compounds have close to 60% oxygen around of 40% aluminum in the presence of terbium as dopant which indicates a stoichiometry close to the expected one for alumina.

Chang Chen   Feng Shi   Keijiro Okuoka   and Hiroki Tanikawa   

A large number of buildings have been built for the urbanization of China in recent decades. A huge amount of material input in construction leads to the problem of high consumption, high emission and the waste of buildings in the future. In the urbanization context, one way to solve the environmental problems is new-type urbanization, which means focusing on resource-conserving cities and environment-friendly cities. This paper presents an analytical method for urban building metabolism by using four-dimensional Geographical Information Systems (4d-GIS). In this research, we establish the database of buildings by calculating floor area, material intensity, material flow and demolition curve, based on the study area (Ezhou City in Hubei Province, China), and present the city by aerial view of 4d-GIS image. 4D-GIS could be applied in material analysis of urban material metabolism and spatial data analysis. Moreover, it can also quantify and visualize urban metabolism and provide references and solutions for urban planning, which is new-type urbanization.

S.A. Golovko   V.A. Gudimenko   A.S. Klimkin   A.M. Pletnev   V.L. Vakula   A.S. Zaika   L.V. Kamarchuk   I.G. Kushch   A.P. Pospelov   A.V. Kravchenko   and G.V. Kamarchuk   

The electric conductivity of point-contact multistructured sensors in a complex medium of the human breath gas has been studied. Considering a large number of parameters which characterize response curves of point-contact sensors, we proved the possibility of using a statistical procedure to assess the reproducibility of sensor operation. To select sensors with similar parameters from a studied set of sensors, the method of cluster analysis was employed. As a result, we first propose a criterion for selection of uniform sensors from sample sets based on sensing arrays, each containing over 200 point-contact sensing elements. We demonstrate the effectiveness of the proposed approach for the selection of uniform sensors in experiments with breath gas exhaled by a volunteer. In this case, pairs of random elements from the formed cluster show a good reproducibility of their sensor images. The selected elements are thus proved to be uniform samples which can be used to study complex gas media, for example, in clinical practice to develop methods of noninvasive diagnosis based on breath analysis.

M. Kartel   Yu. Sementsov   S. Mahno   V. Trachevskiy   and Wang Bo   

The structural and physico-chemical characteristics of thermoplastic polymers filled with multiwall carbon nanotubes (CNTs) such as polyethylene (PE), polyamide 6 (PA 6) and layered fiberglass with PA 6 are investigated. The influence of their concentrations and homogeneity degree of nanotubes distribution is studied. The properties of new composites are compared with the well investigated polytetrafluoroethylene (PTFE)-CNTs and polypropylene (PP)-CNTs systems. It is shown that an addition of CNTs into thermoplastic polymeric materials leads to the significant changes in structural characteristics, growth of strength, electrical, thermal properties. It is coursed by the formation of CNTs continuous network in the original matrix, the crystallinity degree of the matrix depending on the concentration of CNTs. In turn, the crystallinity degree of the matrix is increased by homogeneity arising of the composite as a result of the strong interaction of the matrix with nanofiller. The changes of not only bulk but also the surface properties of the composites are observed, which explains the best biocompatibility of the nanocomposites observed in natural conditions experiments (in vivo).

Yu-Ting Siao   and Tzer-Shin Sheu   

MgO-M_xO_y (M=Fe, Ni) oxide powders were prepared by a direct drying technique and a co-precipitation method for comparing their physical properties. These dried nitrate precursors or hydroxide precipitates were subsequently calcined at 550℃ to transform themselves into oxides, respectively. Calcined oxide powders were sintered at 1100℃ to determine their crystal structures, microstructures, and electrical properties at room temperature. As to crystal structures, sintered Mg_1-xFe_xO_1+y and Mg_1-xNi_xO (x=1/3, 1/2, 2/3) specimens contained spinel and rock salt (NaCl or MgO) crystal structures separately. Electrical resistances of these sintered specimens decrease as the measuring frequency of LCR increases. Sintered specimens obtained from the co-precipitated powders had slightly lower electrical conductivities. At a low measuring frequency of 30-3000Hz, these polycrystalline grains have a grain electrical conductivity of 1.0-9.0*10^-4 S/m^-1 in the semiconductor range. As to microstructures, grain size of these sintered specimens was 0.1-1.0 μm. Relationships between crystal structure, microstructure, and electrical properties were discussed. From this preliminary investigation, these magnesium-containing oxides were a possible cathode material for the secondary magnesium battery.

Sneha M   Meenakshi Sundaram N   and Kandaswamy A   

Hydroayapatite (HAp) nanorods were widely used in biomedical fields such as multifunctional drug delivery systems, bone tissue damages and for dental applications. Here, rod shaped HAp nanoparticles with uniform morphology and controllable size were successfully synthesized without any templates by hydrothermal method. Powder X-Ray diffractometer (XRD), Optical Micrographs (OM), Nitrogen adsorption and desorption studies (BET), Field Emission Scanning Electron Microscope (FE-SEM) and Transmission Electron Microscope (TEM) were used to characterize the structure and composition of the prepared HAp samples. The biocompatibility of the prepared nanorods was tested against MG 63 human osteosarcoma cell lines using MTT assay. The results confirmed that the synthesized HAp nanorods are biocompatible, high purity in nature and high aspect ratio with mean width of 10 nm and mean length of 100 nm. Thus the prepared hydroayapatite nanorods can be used as drug carrying vehicles for hard tissue repair, bone regeneration, bone tissue engineering applications and as strength-enhancing additives for the preparation of biocompatible nanocomposites with improved mechanical properties.

Drahosh Vesely   and Lucia Castro-Diaz   

The chemical degradation processes of HDPE at 110℃ in air have been studied using light microscopy, FTIR analysis, micro-hardness and OsO₄ staining. It is shown that carbonyl groups C=O, (as detected by FTIR) are formed only in the surface layer and the effect on mechanical properties is marginal. On the other hand the formation of isolated and conjugated C=C double bonds (as detected by OsO₄ staining), show that cutting properties and micro-hardness are significantly altered. The progress of the degraded layer follows a diffusion process with sharp front and saturated concentration behind. An attempt is made to explain these observations by formation and mobility of free radicals. It is also shown that processing method, injection or compression moulding, can significantly influence the degradation process and the mechanical performance of the moulded component.

S. V. Ranganayakulu   B. Samrat Goud   P V Sastry   and B. Ramesh Kumar   

Acoustic Emission (AE) is one of the versatile tools to study the materials and associated defects non-destructively under dynamic or static stress load conditions. The experiments planned to study Acoustic Emission system have to be calibrated with various resonant frequency band sensors and stress levels appropriately. This practice covers requirements for the calibration of acoustic emission sensors. The calibration yields the frequency response of a sensor to acoustic waves of the type which normally comes upon in acoustic emission work. The source producing the signal is used for the calibration that increases on the same surface of the test block as the sensor under testing. The calibration represents primarily of the sensor sensitivity to Rayleigh waves. The sensitivity of the sensor is determined for excitation within the range of 1000 KHz to 1KHz. The sensitivity value is usually determined at frequency approximately 1 KHz apart. The AE sources are generally from high intensity stress zones, cracks or defects in the materials under mechanical loads. The acoustic sound signals generated in the dynamic load conditions like burst or continuous emissions must be correlated with parameters such as velocity, time and displacement within the testing system. AE - 4 Channel Acoustic Emission Detection System (procured from Physical Acoustic Corporation, USA) with various frequency band sensors covering wide range is used in this study for the calibration procedure establishment. AE sensors are arranged in vector and matrix mode for signal analysis through AE parameters. In order to deduce physical description of AE sources from recorded waveforms, a well characterized and calibrated AE sensor is required for study of signal analysis. The present paper reports the estimation of the physical quantity measured by the sensor i.e., velocity of material under test. Subsequently, AE source is used for sound signal to travel in the material such that velocity of the material is calculated by manual displacement and time mode. Calibration of sensors is evaluated by shear velocity and experimental standardization studied by the arrangement of different kinds of sensors namely - R6ά, WS ά, PK15I and PK6I. The calibration procedure and standardization for testing of the materials is established and reported.

Guy-Marie Vallet   Michel Dunand   and Jean-Francois Silvain   

In this present work, two methods for dispersing carbon nanotubes into the copper matrix were tested: a Solid Route process where CNTs are simply mixed with the copper powder and a Liquid Route process where CNTs are dispersed in a copper salt solution and then mixed with the metallic copper powder. Powders are sintered by uni-axial hot pressing process under vacuum atmosphere at 650°C and thermal conductivities of composite materials were measured using the laser flash method. Results are compared with a theoretical model of Nan et al. which enables to predict the thermal conductivity of materials containing CNTs. Comparison of experimental and theoretical results tends to prove that CNTs are 2D-randomly dispersed in a plane perpendicular to the pressing direction during uni-axial hot pressing process. Moreover, an increase of +7% of the thermal conductivity is shown for the composite material containing 1 vol. % of CNTs into the copper matrix.

Devpriyo Ghosh   Sarthak Nangia   Sourav Chakravarty   Sharwin Maben   and Satya Shankar Sharma   

The medium carbon low nickel chromium steel is a widely used high strength low alloy steel that provides an advantageous combination of strength, hardness, toughness and ductility for machine part members. It has been widely used for fabrication of parts like gears, cams, piston rods and shafts to name a few. This steel may be subjected to general conventional heat treatments to substantially alter its mechanical characteristics. The typical microstructure of hardened steel shows a martensitic matrix responsible for its strength and wear resistance. Before hardening and tempering, normalizing heat treatment was given to standardize the microstructure. In this study tensile, microstructure and hardness specimens were prepared and subjected to Hardening and Tempering heat treatment. The tensile strength of each specimen including the as-received was tested in an electronic tensometer. Microstructures were recorded on heat treated as well as untreated conditions. Rockwell hardness test was performed on each of the hardness specimen including the as-received one.

Dorin Catana   

Thermomechanical treatment consists in using two classic manufacturing methods. This type of treatment was applied to studied high-speed steel (HS2-9-1-8). The tests performed aimed to establish the influence on the hardness and wear of the high-temperature thermomechanical treatment (HTTMT) applied to studied steel. The application of an additional plastic deformation (the deformation degree between 45 – 75%) positively influences the hardness and wear value. Being a HTTMT, the plastic deformation was followed by quenching, the utilized agent being the oil or compressed air. When the quenching agent was the oil the hardness increased by 6-7% and the wear diminished up to 40%. Samples thermally treated in the classical way were used as comparison elements. The study performed shows that a favourable evolution of the analysed properties appears when the deformation degree is between 55 and 75%. The air compressed quenching sets for the analysed characteristics, the same evolution with those obtained during the oil quenching. The increased hardness for the studied high-speed steel utilized at cutting tools manufacturing will generate a slower wear of the cutting edge that means important economies in cutting process.

D. Mansour   B. Demri   and S. Belkaid   

Surface treatments of materials have attracted intensive studies in recent years, and considered as an important way for providing protection properties. In this paper, oxygen plasma treatment was used on API 5L X52 carbon steel. The produced deposit was characterized by different methods; optical and electronic microscopy, microhardness measurements and X rays diffraction. The resulting layer has been evaluated by electrochemical methods and pitting corrosion tests. The results showed that Fe₂O₃, which resulted from coating treatment by oxygen plasma, improved the superficial microhardness of steel. In chemical terms, pitting corrosion tests in corrosive solution showed a clear decrease of the weight loss and pitting percentage in coated coupons. Moreover, electrochemical corrosion tests (linear polarization and electrochemical impedance spectroscopy tests) showed that the produced deposit after coating gived a good protection against corrosion. This study demonstrates that oxygen implantation provides protective properties to API 5L X52 carbon steel.

Andrei Klyndyuk   Natalie Krasutskaya   Lyudmila Evseeva   Ekaterina Chizhova   and Svetlana Tanaeva   

Using solid-state reactions method the ceramic samples of Na_0.89Co_0.9M_0.1O₂ (M = Sc, Ti, Cr–Zn, Mo, W, Pb, Bi) solid solutions had been prepared, their lattice constants had been determined and their microstructure, thermal expansion, thermal conductivity, electrical conductivity and thermo-EMF had been measured, and their power factor and figure-of-merit values had been calculated. Effect of the cobalt substitution by other metals in the Na_0.89CoO₂ on the crystal structure and physicochemical and functional properties of its derivatives was analyzed. It was found that Na_0.89Co_0.9M_0.1O₂ cobaltates are the p-type conductors, which linear thermal expansion coefficient (LTEC) values varied within (1.24–2.05)·10^-5 K^-1. It was found that the best thermoelectric properties among the oxides studied possessed Na_0.89Co_0.9Ni_0.1O₂ and Na_0.89Co_0.9Bi_0.1O₂ solid solutions which power factor and figure-of-merit estimated values at 1100 K are equal to 0.919 and 0.660 mW/(m·K) and 1.12 and 0.83 respectively.

M. Elhadi   M. ElMassalami   and B. Ouladdiaf   

We investigated in the B site-selectivity and induced modifications in the crystal structure, when B is introduced into the B2-type AlNi matrix (Pm-3m; Al at 1a, Ni at 1b). A rapid-quench from higher temperatures of all nominal AlNiB_x and Al₂Ni₃B_x/3 compositions (0≤ x ≤ 3) leads to the formation of a cubic solid solution. On the other hand, diffraction studies indicate that all (unquenched) AlNiB_x (1≤ x ≤ 3) compositions are chemically unstable. By contrast, for 0≤ x ≤ 1 there is a strong preference of B to enter substitutionally into the 1b site: then composition balance is achieved by transferring a Ni atom into a 1a antisite.

Mehdi Shahedi Asl   and Mahdi Ghassemi Kakroudi   

Monolithic ZrB₂ ceramic and its composites, with 5 to 30 vol. % SiC, has been prepared by hot pressing at temperatures of 1700, 1850 and 2000℃, for 30 minutes under relatively low pressure of 10 MPa. Densification behavior of ZrB₂-based composites is improved by the addition of SiC particulates. The fracture surface of monolithic ZrB₂ ceramics shows a grained structure, with faceted ZrB₂ grains, as the fracture appears to spread prevalently along an intergranular path. The ZrB₂/ZrB₂ boundary interface is seemingly free of any secondary phases. The microstructure of ZrB₂–30 vol. % SiC composite, hot-pressed at 1700℃, is consistent with measured porosity for the sample that has ~8% open pores, nearly without closed pores. It seems that mechanical interlocking between ZrB₂ and SiC is an important mechanism for densification. In the microstructure of specimens consolidated at 1850℃, neck formation between ZrB₂ particles is visible. In contrast, relatively fully dense samples are obtained by hot-pressing at 2000℃. Intergranular SiC particles inside ZrB₂ grains show the occurrence of mass transfer among ZrB₂ particles, which in effect brings the elimination of pores to a fortunate ending. Efficient mixing of starting powders is very critical in order to achieve a fine-grained homogenous microstructure.

Andrei Klyndyuk   and Yekaterina Chizhova   

The Bi_0.85Nd_0.15FeO₃, BiFe_0.85Mn_0.15O₃, and Bi_0.85Nd_0.15Fe_0.85Mn_0.15O₃ ferrites solid solutions were synthesized and their crystal structure, magnetic susceptibility, thermal expansion, electrical conductivity, thermo-EMF and dielectric properties were studied. It was found that Bi_0.85Nd_0.15FeO₃ and BiFe0.85Mn0.15O3 had rhombohedral structure (space group R3c), but Bi_0.85Nd_0.15Fe_0.85Mn_0.15O₃ one had orthorhombic structure (space group Pnma) and all the complex oxides studied were the antiferromagnetic semiconductors of p-type, which electrical conductivity values were larger than for unsubstituted bismuth ferrite BiFeO₃, Neel temperature and thermo-EMF coefficient sharply decreased at partial substitution of iron by manganese and linear thermal expansion coefficient values varied within (10.0–13.4)•10^-6K^-1. The values of charge carriers transfer parameters in (Bi,Nd)(Fe,Mn)O₃ phases were calculated.

Omed Gh. Abdullah   Dlear R. Saber   and Luqman O. Hamasalih   

Solid polymer electrolyte films based on polymer blends of poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO), with different concentration of copper (II) chloride (CuCl₂) were prepared using casting technique. Optical studies were performed using Fourier transform infrared (FT-IR) and Ultraviolet-visible (UV-Vis) spectroscopy. The optical properties of these films were varied by varying CuCl₂ concentration. The results show the absorption edge for electrolyte samples shifts toward a lower energy region by increasing the salt concentration, leading to the band gap reduction. The band gap energy data showed that the incorporation of CuCl₂ into the polymeric system causes charge transfer complexes in the blend polymer, which lead to increase in the electrical conductivity, by providing additional charges in the lattice. The PVA/PEO/CuCl₂ solid polymer electrolyte films exhibit good UV shielding properties in the wavelength range from 190 to 400 nm.

Humayun Kabir   Md. Abdul Gafur   Farid Ahmed   Farhana Begum   and Md. Rakibul Qadir   

The bamboo fiber and PVC foam sheet composites were developed via hot compression molding process. Different percentages (0%, 5%, 8%, 12% and 15%) of bamboo fibers were introduced into the PVC foam sheets. Various physical and mechanical properties of the composites have been investigated. Bulk density decreases with the increase of percentage of fibers introduction to the PVC sheets. Percentage of water absorption was found to increases with the soaking time for all the samples. Mechanical properties e.g., tensile strength, flexural stress, flexural strain and tangent modulus of the composites are observed to be increases while the tensile strain decreases with the subsequent fiber addition to the PVC sheets. At the same time, the Young's modulus found to be increased up to 10% of the bamboo fibers introduction and then decreases with the further enhance of the fiber content. The maximum Young's modulus (1250 MPa) was found for 8 % of bamboo fiber to the PVC composite sheets. Thermal analysis confirmed the better thermal stability of bamboo fiber PVC composites.

A. Canakci    T. Varol    S. Ozsahin   and S. Ozkaya   

A neural network (ANN) model was developed to predict the abrasive wear behavior of AA2024 aluminum alloy matrix composites reinforced with B₄C particles. Al2024-B₄C powder mixtures with various reinforcement volume fractions (3–10%) and particle sizes (29µm and 71 µm) were prepared and Al2024-B₄C composites were produced by stir-casting technique. The model was based on three layer neural network with feed forward back propagation learning algorithm. A sigmoid transfer function was developed and found to be suitable for analyzing the abrasive wear behavior of composites with the least error. The training data are collected by the experimental setup in the laboratory. The trained model was used to study the effect of ceramic particle size and volume fraction on the abrasive wear of Al2024–B₄C composites. By comparing the predicted values with the experimental data, it was demonstrated that the well-trained feed forward back propagation ANN model is a powerful tool for prediction of abrasive wear behavior of Al2024-B₄C composites.

Amal Nassar   and Eman Nassar   

In this study, the effect of extrusion temperature on the machinability of 6061 Al-alloy as cast and as matrix reinforced with 15% SiC particles were investigated for the as received and extruded at two different temperatures 600 and 620℃. Machinability of the 6061 Al-alloy is tested based on tool wear and surface roughness. The experimental work has revealed that decreasing the extrusion temperature from 620℃ to 600℃ %, results in increasing the tool wear by 50% and machined surface roughness by 9%.

Drahosh Vesely   and Ming Zhu   

Understanding diffusion and permeability processes in organic materials is important for applications to structural components, protective coatings or packaging. In this work some basic behaviour of solvent diffusion into and through a polymer are studied using acetone and un-plasticized polyvinyl chloride at room temperature as model materials. Special cell for gravimetric measurements is used to provide data on diffusion and permeability rates through samples of different thicknesses. It is shown that the rates of mass transport are slowing down with thickness for diffusion and also for permeability, as expected. However permeability mass transport is slower than mass delivered to the outer surface by diffusion. This is explained and experimentally verified by insufficient saturation of the surface layer, as the solvent evaporates before a full saturation is reached. When the outer surface layer is pre-saturated with solvent, permeability will increase several times. When evaporation is restricted (e.g. closed cavity) the liquid solvent will accumulate, filling up the cavity. Concentration profiles, measured by infrared microscopy, confirm this observation. It is suggested that the experimental data can be explained by using chemical potential and chemical reaction kinetics.

Aykut Canakci   Temel Varol   Serdar Özkaya   and Fatih Erdemir   

In the present work, three different types-layered Al-B₄C functionally graded materials were fabricated via powder metallurgy. The Al-B₄C powder mixtures were cold pressed in two different pressures (400 and 500MPa) and sintered at 600℃ for 3h under argon atmosphere. After investigating the pressure and sintering process of the mixed powder with different compositions, the density, microstructure, elemental distribution and hardness variation of the produced FGMs were evaluated. A detailed characterization of the microstructure of the FGMs was carried out using scanning electron microscopy and energy dispersive X-ray analysis. The results revealed that the mechanical properties of the Al-B₄C FGMs system strongly depend on constitutional variation, and display various graded distributions as well. The microstructure of FGMs so produced exhibits a gradual change of hardness from 165BHN in aluminum to 250BHN in B₄C region.

Badis Bendjemil   and Faming Zhang   

The polycrystalline dense Ti₃SiC₂ based ceramic have been prepared by several techniques. The effects on the addition of TiC or SiC are also studied. Ti₃SiC₂ has an unusual combination of electrical, thermal and mechanical extraordinary properties. It has furthermore damage tolerant and oxidation resistance. In this work we have produced Ti₃SiC₂ by electro-thermal explosion chemical reaction started with high current density (680 amperes) followed by uniaxial pressure. The microstructures of the materials were studied using XRD, SEM and EDX. The surface of Ti₃SiC₂ was studied by means of X-ray photoelectron spectroscopy (XPS). High resolution C_1s, Si_2p, Ti_2p, Ti_3s core level spectra are inspected in terms of electronic structure. Valence band spectra will be performed to confirm the validity of the theoretical calculations.

Volodymyr Maslov   

The investigations have shown the following promising tendencies in technologies for joining materials used in precision techniques: Removal of the damaged surface layer by chemical etching the joined surfaces allows, up to 6-fold enhancing both durability of part and glue conjunction between it. To modify properties of silicon-organic epoxy glue not only near the surface of combined parts but over the whole thickness of the glue joint, offered have been glue compositions based on thermostable silicon-organic glue with embedded in it filler in the form of powder consisting of nano-dimensional (15 to 20 nm) particles of zirconium oxide in the amount up to 20 mass. %. The developed diamond-glue composition enables to shorten the duration of cooling the glue conjunction leucosapphire-copper to cryogenic temperature (from the room one down to 80 K) by 1.5 times and obtain the 6-fold increased durability, as well as higher reliability and longevity under thermal shocks. This composition is also recommended to provide efficient and uniform heat removal in solar panels. Deposition of the chromium vacuum coating with the thickness 50 to 100 nm modifies the Teflon surface and allows using the traditional glues for joining the parts processed in this way.

A. Kumaresh   and R. Arun Kumar   

Organic non-linear optical materials receive much attention owing to their very large second order nonlinearities, ultra-fast response times and high optical damage thresholds. In the present work, low temperature solution growth technique has been employed to grow non-linear optical hippuric acid (HA) C₆H₅CONHCH₂COOH single crystal with dimensions 10 x 6 x 3 mm³ were obtained in a period of 18 days using acetone as solvent. Powder XRD analysis reveals that the crystal belongs to an orthorhombic system with space group P2₁2₁2₁ and lattice parameters were found to be a = 8.8514 Å, b = 9.0842 Å, c = 10.5807 Å. UV optical absorption analysis on these samples reveals the transparency of the crystal in the visible region. The bonding structure and molecular associations due to chemical reactions were analyzed by FTIR spectroscopy.

Pierre Ziade   Christophe Palermo   Antonio Khoury   Roland Habchi   Myriam Rahal   and Luca Varani   

The electronic band structures of zinc blende and wurtzite GaN and InN are calculated using the empirical pseudopotential method, with the form factors adjusted to reproduce correctly the most important band features. To this end, a comprehensive analysis and comparison with several experimental and theoretical data reported in the literature is performed. Relevant energy spacings as well as direct and indirect band gaps are then derived from the band structures. The electron effective masses at high symmetry points are also obtained using a parabolic line fit. The calculated parameters are reported together with existing data so that they can be easily compared and used in the interpretation of experiments and for numerical simulation purposes.

Mariusz Wójcik   

The considerable and programmatic reasons for an improvement of the theoretical base in recently most rapidly developing segment of science – the materials engineering – where controlling of the process of creation of a new usable material acquires presently a reasonable meaning in the world, have been discussed in this paper. Also has been presented some new proposition of an approaching to the question basing on the idea for organisation of an intellectual structure, jointing the activities of an existing group of theoreticians and experimenters, for whom the controlling basing on new theories become an important impulse and a strong instrument helping in the achievement of the above aim. It is considered that the proposition for formulating of some central limit theorem (CLT), that will correspond to some technological process on the level of a small set of particles which can grow thick in its structure, passing into infinitely increasing number of particles by the way in known continual process, described, for example, by known differential equation – that it is a proper way for recognition of what is going on in the nano and microstructures determining the nucleation and the growth of the crystals. It is assumed that in a case of appearance of some constructive reactions to the doubts discussed in the paper, it is a chance for establishing a suitable group of person discussing above problems and being able to create the theoretical description as well as to gain effectively new technical solutions, useful in the further, successful development of the materials engineering in the world.

M.Murali   M.Sambathkumar   and M.S.Senthil Saravanan   

AA7075/TiO₂ in situ composites with different mass fractions of reinforcement were fabricated by stir casting method. During fabrication TiO₂ reacts with base alloy and form an in situ composites leading to a uniform distribution of reinforcements. The phase analysis and morphological characterization of composites were studied using x-ray diffraction techniques and scanning electron microscope. Mechanical test were done on the samples to study the behavior during load at different strain rates. Effect of reinforcement and the strengthening mechanism were studied in detail.

Olga V. Yushchenko   and Anna Yu. Badalyan   

Within the framework of the canonical Hamilton system the behavior of active nanoparticles was investigated. On the basis of the phase portraits the kinetics of the system was studied. The transformations of the nanoparticle’s internal energy into the kinetic energy of the motion and into the total mechanic energy were considered.

S. F. Matar   M.A. Subramanian   and J. Etourneau   

The “Geo-inspired” novel concept is proposed, based on using the crystal and bonding characteristics of existing minerals to devise novel man-made materials. It is also used to address grand challenges in designing next generation functional materials such as new ultra-hard materials and layered oxides. Extension is proposed for identifying exotic chemical systems, in order to further stress its generality.

Kripa M. Suvarna   K. RajenUdupa   and A. O. Surendranathan   

The present study is pertaining to the influence of biofilm on pitting corrosion of UNS 31603 stainless atel in the sea water medium. These materials are welded and aged at 450℃ for 10000 hours. The corrosion behavior of weld materials are compared with similarly aged base metal (BM). Corrosion studies were conducted using potentiodynamic studies in the presence and absence of bacteria G.rose at temperatures 40℃, 25℃ and 10℃ in sea water medium. Role of bacteria and its susceptibility to pitting were determined by its biofilm presence helps in corrosion protection to certain extent. But severe corrosion occurred when biofilm breaksdown. The microbial adhesion was tudied using Scanning Electron Microscope (SEM and Fourier transform Infra Red Spectrometre(FTIR).

Alexander Krajnikov   Fumio Morito   and Mykola Danylenko   

The mechanical properties and microstructure of Mo-Re alloys and welds were examined after low- and high-temperature irradiation focusing on the effects of Re concentration, phase stability, microstructural changes and impurity redistribution. Ductility improvement and fracture mode changes from intergranular to transgranular are clearly observed in Mo-Re alloys with an increase in Re content. Neutron irradiation causes hardening of the matrix and concurrently reduces its ductility. The hardening effect is rather limited and unstable after low-temperature irradiation because of the lack of ductility. The damaging effect of neutrons is smaller and hardening of the matrix is more pronounced after high-temperature irradiation. Intensification of homogeneous nucleation of Re-rich phases throughout the bulk is observed after high-temperature irradiation in all of the Mo-Re alloys studied. As a result, the microstructure and strength of all parts of as-irradiated welds equalize and show approximately the same level of strength.

V A Zhelnorovich   

Within the framework of the relaxation model, the solutions describing transverse and longitudinal magnetoacoustic waves are obtained for magnetizable liquids with an arbitrary orientation of the wave vector and the magnetization vector. It is shown that two different transverse waves exist in magnetizable liquids according to the relaxation model. Limitations are established on the internal liquid energy at which the velocity of sound is decreased from the maximum value when the wave is propagated along the magnetization vector to the minimum value when the wave is propagated perpendicular to the magnetization vector. Conditions are also established at which the velocity of sound, according to the experimental data, increases as the liquid magnetization and wave frequency increase.

Mashekov S.A.   Mashekova A.S   Smailova G.A   and Bekmukhanbetova Sh.A.   

The mill of new construction is proposed in the article. To calculate the specialized metal forming processes the software of finite element analysis - MSC Super Forge MSC Visual Nastran 4D was used. Stress-strain state (SSS) of the rolled workpiece and heavy-loaded units of the proposed mill was calculated. The influence of the rolling temperature regimes on formation of hot-rolled strips cross-section was investigated. The hot-rolled strips were rolled on longitudinal wedge mill. It is proved that the workpiece is deformed in the conditions of “soft” SSS in a mill of new construction, in other words the amount of the elastic deformation and displacement of the rolls units are small. The investigation has also proved sufficiently high fixity of the joints of roller assembly work stand as well as that the equivalent voltage does not exceed the maximum permissible value for the material strength in heavy-loaded units of the mill.

E.A. Konshina   I.F. Galin   and E.O. Gavrish   

Electrical characteristics of the nematic LC cells with 3.5 nm semiconductor CdSe/ZnS quantum dots (QDs) were investigated. We observed variation of the LC cell capacitance with QDs concentration about 0.18 wt. %. The capacitance grown to three orders of magnitude at primary measuring under voltages below the Fredericks threshold and then it dropped. Repeated tests shown that the capacitance maximum of dependence decreased and disappeared after repeated measurements of the LC cell. The maximum arose again after applying to the LC cell of the alternating-current electric field with voltage of 30 V at a frequency of 1 kHz for 10 minutes. Changing of the capacitance was observed in the result of mobile ions interactions of liquid crystal with QDs in the electric field. That contributed to an aggregation and moving charged nanoparticles in the direction of substrates of LC cell as well as their reverse motion to a centre under action of applied voltage onto the LC cell.

W.Chen   A.N.Kalashnikov   R.E.Challis   and M.G.Somekh   

Ultrasonic NDE of case hardening of steel parts presents an attractive alternative to destructive assessment still used in industry. This experimental study showed that the ultrasonic assessment could be conducted by measuring two average times of flight across different dimensions of a hardened test sample. The consistently observed difference in the corresponding average ultrasound velocities was above the estimated accuracy of the measurements, and the scattered individual calculated values formed distinct clusters. The results were obtained by using a high resolution data acquisition instrument with the equivalent sampling frequency of 1.5 GHz and 512 averages, and differential measurements of the time of flight by determining zero crossings of the echo waveforms.

E.L. Pankratov   and E.A. Bulaeva   

In this paper we analyzed distribution of temperature in a reactor for epitaxial growth from gaze phase. Based on the analysis it has been formulated recommendations to increase homogeneity of distribution of temperature in depth of heterostructure, which has been grown in the reactor.

M.S. Payzullakhanov   

Barium titanate ceramic samples were synthesized from mixture of TiO₂+BaCO₃ under influence of concentrated light flux of 200 Wt/cm² at 2000℃ followed by quenching (A-type) and by the ceramic technology at 1350℃ followed by cooling at the rate of 100℃/min (B-type). The both types of samples had tetragonal symmetry lattice with the parameters a=0.399 nm and c=0.403 nm, however their tetragonality degree δ = c/a – 1 slightly differed (0.01 and 0.007 for A- and B-type, respectively). Dielectric permittivity value was 3800 for A-type and 3400 for B-type; bending deformation began at 66 MPa for A-type and 49 MPa for B-type.

Shaikh M. Javaria   

This research presents the diagnosis, definition of pathology and damages and possible conservation intervention of a selected portion of Genose Villa Zerbi in Reggio Calabria which is been converted into a museum. It focuses on visual and structural intervention and integrity of the new with old, on the basis of diagnosis of selected component of the building and provides analysis based on the field study. Furthermore, the clear intension has been that the intervention should be reversible that is; to save the building from further deterioration, and to highlight clearly the difference to the future scientist, so that if any new technology is discovered, offering a better solution of the same problem, the present solution can be replaced.

E.L. Pankratov   and E.A. Bulaeva   

In this paper we analyzed redistribution of a dopant, which implanted in a heterostructure, during annealing of radiation defects. The annealing has been done after overgrowth of the damaged during implantation area. The analysis has been verified recently obtained effects of increasing of sharpness of implanted-junction rectifier and homogeneity of distribution of dopant in enriched by the dopant area. At the same time using of overlayer gives us possibility to additionally increase homogeneity of dopant distribution.

Dr F. Al-Hasso   

Glass coatings on carbon steel substrates have been produced by spraying glass feedstock powders using combustion flame spraying. Glass powders with different compositions and particle size were tested; coatings with increasing soft glass A volume fractions in hard glass B base (0%, 10%, 20%, 30%) were sprayed. Furthermore, two different particle size (53-63 µm and <45 µm) of 30wt%A glass feedstock powders were employed. The microstructures of coatings were examined, characterised and the porosity was quantified. Vickers microhardness, fracture toughness and adhesion strength have been measured. The comparisons between the microstructure of coatings produced by conventional enamelling and thermally sprayed were investigated. Uniform structure and large pores produced in conventional enamels and non-uniform structure with small size pores produced in thermally sprayed coatings. It was observed that adhesion strength increased, hardness decreased and the fracture toughness did not change with increasing glass A content. Refining particle size of 30wt%A glass composition increased the hardness and did not affect the adhesion and fracture toughness of coatings.

Vladimir. G. Plekhanov 

As is well - known isotopes of a given element have identical numbers of protons but differ in the number of neutrons making up their nuclei. Particularly, in crystalline solids, this difference in nuclear mass most directly affects vibrational phenomena, i.e. phonon frequencies and all phonon - related properties. These include exciton binding energy, electronic band gaps, lattice constant, local and crystalline vibrational modes, self - diffusion in bulk material as well as isotope superlattices (see, e.g. reviews [1, 2]). The experience of the past shows that throughout constant technology improvement electronics(optoelectroelectronics)has become more reliable, faster, more powerful, and less expensive by reducing the dimensions of integrated circuits. These advantages are the driver for the development of modern microelectronics. The long - term goal of this development will lead to nanoelectronics. Advancing to the nanoscale is not just a step toward miniaturization, but requires the introduction and consideration of many additional phenomena. at the nanoscale, most phenomena and processes are dominated by quantum physics and they exhibit unique behavior. Nanotechnology includes the integration of man - made nanostructures into large material components of system (see, e.g. [3, 4]). Nanoscience and nanotechnology are concerned with materials, structures and systems whose components exhibit novel and significantly modified physical, chemical properties due to the nanoscale sizes. New direction of nanosciene is isotopetronics, who is studied the more low - dimensional size, as a rule the sizes of the sample of isotopetronis compare to the atomic size. Over the last five decades the large number of experimental and theoretical studies of isotopetronics have created the new branch of material science, which is called the isotope - based material science. Isotopetronics may find applications in quantum computing, nanoscience and spintronics. This review contains a brief introduction to the isotope - based material science.

Alexey Kharlamov Marina Bondarenko Ganna Kharlamova Nadezhda Gubareni and K.B.Shilpashree Fomenko 

The new method of pyridine pyrolysis is created, the some part of pyrolytic soot of which contains onion-similar carbon with high (10-13%) contents of nitrogen (or “pyridine carbon”). Nanoparticles of this “pyridine carbon” are formed only in a gas phase at the expense of reactions of polymerization and polycondensation of molecules of pyridine and by reactionary flow in a low-temperature zone of reactionary space are taken out. Onion-structures of the greater size and with the small contents of nitrogen (~1.0 %) together with nanotubes and filaments are products of heterogeneous reactions between carbon fragments of destruction of pyridine molecules, which mainly on the most high-temperature surface of quartz reactor are carried out. Nitrogen-containing fragments of a destruction of a molecule С₅H₅N mainly as НCN in a gas flow from sphere of reaction are removed. The growth of carbon nanostructures is realized at the expense of heterogeneous reactions but in absence of the metallic catalyst. The products were characterized by methods X-ray photoelectron and IR spectroscopy, scanning, transmission and high resolution transmission electron microscopy, X-ray diffraction and chemical analysis.

Dipali Rai Goutam Kumar Jha Prasenjit Chatterjee and Shankar Chakraborty 

Since decades, proper material selection plays an important and crucial role in an effective manufacturing system for superior production quality, cost optimization and improved productivity. Systematic selection of materials for a given engineering application begins with the study of different material selection properties and their related costs with specific application capabilities. Wrong selection of materials often leads to huge cost contribution and eventually drives an organization towards early product failure. So, the designers need to identify and select proper materials with specific functionalities in order to get the desired output with minimum cost involvement. But, the selection of proper materials for engineering applications is not an easy task to perform. While choosing the proper material for a specific industrial application, there is not always a single definite selection criterion. Designers need to consider a huge number of material selection-attributes and a large number of alternative materials with complex relationships between various attributes. A systematic, efficient and easy approach for material selection is thus required to help the manufacturing organizations for selecting the best material for a particular application. This paper focuses on the application of a compromise ranking method in the perspective of regret theory as a multiple-criteria decision-making (MCDM) tool for solving a material selection problem in a given manufacturing environment. A complete list of all the prospective materials from the best to the worst is obtained, taking into account different material selection attributes. The ranking performance of the proposed method is also compared with that of the original compromise ranking method.

Alok Kumar Gupta Archana Gupta Sudhanshu Tripathi Vyoma Bhalla and Jamal Montafej Singh 

This work is focused on three types of ultrasonic velocities (V1, V2 and V3) in Mg and Cd hcp metals. These are determined using the SOEC and TOEC at room temperature. Ultrasonic waves were supposed to be propagated along different directions with the crystal axis (z-axis). Finally ultrasonic attenuation in Mg and Cd are evaluated at room temperature utilizing the SOEC and TOEC of the materials. Average wave velocity is highest at θ=55° along z-axis in these materials. The contributions of the elastic constants, thermal conductivity, thermal energy density, ultrasonic velocity and acoustic coupling constant to the total attenuation are studied.

A.K. Yadav Devraj Singh Y. E. Razvodovsky Tripathi Vyoma Bhalla and R.R. Yadav 

The anisotropic elastic constants of a B2 structured iron aluminide FeAl (Fe-40 at. % Al) alloy at different temperatures are computed using Coulomb and Born Mayer model. The temperature dependent ultrasonic properties of the alloy along with other associated parameters are determined using the elastic constants. The correlation between the mechanical and thermal properties makes ultrasonic properties a suitable, nondestructive tool to study the physical state of FeAl alloy. The results of present investigation are discussed in correlation with the microstructural phenomenon like phonon–phonon interaction and the other thermophysical properties. Temperature dependence of ultrasonic attenuation along different crystallographic directions reveals some typical characteristic features.

Angham. G.Hadi Farhan Lafta Ahmed Hashim Hussein Hakim Abbas I.O.Al-Zuheiry Saba R.Salman and Hind Ahmed 

The present work is concerned to study the optical constants of the PVA/BaSO₄ composites at different concentrations of barium sulphate. The samples are prepared by casting method technique with different proportion of PVA and BaSO₄. The absorption and transmission spectra have been recorded at the wavelength ranges (200-800)nm by using (UV/160/Shimadzu spectrophotometer). The results show that (The absorption coefficient, extinction coefficient and energy gap of the indirect allowed and forbidden transition) vary with the concentration of barium sulphate BaSO₄ dopant.

E.L. Pankratov and E.A. Bulaeva 

In this paper we introduce an approach to decrease dimensions of planar field-effect heterotransistors by using dopant diffusion in a semiconductor heterostructure and optimization of annealing time. Some conditions to maximal increasing of the effect have been formulated. We also introduce an approach to decrease price of manufacturing of considered transistors due to simplification of their construction.

Vitaly J. Klenin and Sergei L. Shmakov 

The paper discusses the complexity and ambiguity of interpretation of plotting binodals (for binary monomolecular polymer + low-molecular-weight liquid systems) or phase separation boundaries (those with a polymolecular polymer) by means of fixing a certain turbidity level when the configurative point moves from the single-phase range towards the phase separation one (the so-called cloud-point curve technique).

Michal Besterci Ferdinand Dobeš Bernard Maake Sülleiová and Oksana Velgosová 

The aim of this paper was to study the influence of different input materials and methods of treatment on the microstructure, mechanical properties and fracture of dispersion strengthened aluminium alloys in the Al-Al₄C₃ system. It was proved that the transformation efficiency of carbon to Al₄C₃ by heat treatment of aluminium with the porous furnace black and electrographite is higher than that of the hard cracked graphite. The size of Al₄C₃ dispersed phase was measured by TEM on thin foil and it was constant and as small as 30 nm. Subgrain size measured in the range of 100 grains in thin foils depended on the carbon type, as well. It ranged from 0.3 to 0.7μm. The temperature dependence of ductility, and reduction of area in the temperature range of 623 – 723 K and strain rate of 10-1 s-1, indicated a considerable increase of properties. In a case when the volume fraction of Al₄C₃ changes from lower to higher, the grain rotation mechanism dominates instead of the grain boundary sliding. The dependence of the minimum deflection rate on the applied force as well as the dependence of the time to fracture on the applied force for two temperature levels (623 and 723 K) by small punch testing is depicted. The anisotropy of the creep properties and fracture using small punch tests for the Al-Al₄C₃ system produced by ECAP were analysed.

Cheshko I.V. Kondrakhova D.M. Odnodvorets L.V. Pylypenko O.O. and Shabelnyk Yu.M. 

The results of study magnetooptical and magnetoresistive properties of multilayers based on Co, Fe and Cu, Ag or Au, in which are formed solid solutions (s.s.) with possible subsequent formation the granular state are presents. The dimensional and concentration dependences of the magnetooptical Kerr effect and magnetoresistance for two-layer systems and multilayers with different types of solubility (for systems based on Cu and Co is unlimited, as for Co and Au, Ag and Co - limited) at different stages of annealing was received and analyzed. Established the basic regularities of influence by processes of formation s.s. (Cu, Co), (Au, Co) and (Ag, Co) in the film systems obtained layering condensation with followed annealing on the magnetic properties on the whole film system. It is shown that in systems where similar processes of formation s.s. are absent (the system based on Fe and Ag) magnetic properties depend only on the concentration of magnetic components and common thickness of the sample.

Sujan Kar Shweta Logad Om P Choudhary Chiranjit Debnath Sunil Verma and Kunwar S Bartwal 

We present investigations on the preparation of lithium niobate, LiNbO₃ nanoparticles using high energy ball-milling. Stoichiometric composition of LiNbO₃ powder was prepared by solid-state reaction method and used for ball-milling. Various milling parameter were optimized to get required particle sizes. Synthesized nanoparticles were characterized for their structure and particle sizes using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. The UV-Visible transmission shows the blue shift in cutoff, which indicate nearly stoichiometric composition of the prepared material. It has been observed that the sizes of particles decreases with increasing milling speed and time. Observed particle sizes were found in the range ~30-60 nm.

I.V. Cheshko Z.M. Makukha L.V. Odnodvorets M.O. Shumakova D.V. Velykodnyi and I.Yu. Protsenko 

In the work the strain effect in magneto-optical (magneto-optical Kerr effect - MOKE) and magnetic properties of thin films and multilayers based on Fe and Pt in unstrained and strained states was studied. The proposed ratio for strain coefficient of MOKE us quantitative characteric this effect. By measuring the Kerr angle for different values of strain and geometry measurements, it is concluded the influence of strain effects on magnetic characteristics of two-layer films and multilayers.

E.L. Pankrato and E.A. Bulaeva 

In this paper we consider an approach to manufacture a field-effect transistor. The approach gives us possibility to decrease dimensions of the transistor in two directions at expense of the third one. The increasing of the third dimension of the field-effect transistor did not compensate full volume of the transistor.

A. Hossain and A. S. W. Kurny 

Effect of artificial ageing temperature on the mechanical properties of Al-6Si-0.5Mg alloy containing 0.5–4 wt% Cu was studied. The solution treated alloys containing different amounts of Cu were aged isochronally for 1 hour at temperatures up to 300℃. The precipitation stages during ageing were monitored by hardness measurements. Tensile and impact properties were determined by standard tests. During artificial ageing, the yield and ultimate tensile strengths were found to increase with ageing temperature; the maximum being attained at peak aged condition. Ductility and impact toughness of the alloys, on the other hand decreased with ageing temperature reaching the minimum at the highest hardness. The addition of Cu resulted in an increase in hardness and tensile strength and substantial reduction of ductility and fracture toughness.