सामग्री विज्ञान और इंजीनियरिंग जर्नल

We have investigated the effect of low-temperature (80ºC) post-deposition heat treatment onto CuInTe2 (CIT) thin films prepared by one-step electrochemical technique. Aqueous precursor solution consisting ionic species of Cu, In and Te with pH 4.0 was used for the growth of CIT layers. The deposition potential was optimized using cyclic voltammetry. Conventional three-electrode geometry was used to electrodeposit CIT thin films onto CdS substrates. The structural, optical, morphological, compositional and transport properties were studied with the aid of XRD, Raman, HRTEM, UV-Visible, FESEM, EDAX, I-V and C-V measurements. As-deposited samples were amorphous in nature, however upon heat treatment highly crystalline CIT thin films with tetragonal crystal structure were exhibited. The values of energy band gap for the films deposited at -0.7 V and -0.8 V versus Ag/AgCl were estimated to be in the range 1.02 eV to 1.1 eV. Compact, uniform, void free and well adherent films were deposited at -0.7 V and -0.8 V. The samples were heat treated at 80ºC for 60 minutes therefore, visible changes in the surface morphology were not observed by SEM. Indium rich films were electrodeposited for -0.7 V and -0.8 V, however upon heat treatment stoichiometric layers were obtained. Schottky diodes are formed with Au metal contact in all cases. The solar cell investigated under illumination at 1.5 AM exhibits the short circuit current density (Jsc), 40.75 mA/cm2; open circuit voltage (Voc), 255 mV; fill factor (FF), 41% and power conversion efficiency (η), 4.01%. This low-temperature heat treatment procedure could be advantageous for the fabrication of CIT solar cells onto flexible substrates.

Except for few attempts to show the high impact load effect, the difference in level of contribution of nanoclay on polymers at their quasi-static and dynamic mechanical behaviors is a lacuna in the available literature. Quasistatic and dynamic responses of a high impact copolymer polypropylene (PP) in its neat and nanoclay-filled forms are presented in this study. The study helped in percentage quantification of differences in nanoclay effect, imposed by the very nature of loadings. The PP-nanoclay nanocomposite (PP+5 wt%nc) is prepared by melt compounding of 5 wt% nanoclay (nc) with PP using twin screw extruder. Tensile specimens for UTM (Universal Testing Machine) were prepared using injection molding machine. Dynamic loading specimens were made for SHPB (Split Hopkinson Pressure Bar) using an extruded sheet. The experiments were performed at strain rates of 10-2 s-1 and 2.2*104 s-1 for quasi-static and dynamic loadings respectively. As a result, the contribution of 5 wt% nanoclay on PP at quasi-static loading is shown to be 2.6%, 10.8% and 13% on Yield stress, Young’s modulus and toughness, respectively. However, significantly different results are observed after dynamic loading experiments. Intense improving contributions of 506% and 53% in impact modulus and impact toughness respectively are observed. While, minor reduction (3.5%) in plateau (Yield) stress is experienced in the case of dynamic impact loading.

Natural Fiber Reinforcement Polymeric Composites (NFRPC) used in the recent days in wide range of industrial applications. For its good environmental properties and availability, natural fibers and natural additives used as reinforcing material for most of polymeric composites. In the present work, polyester composites filled by date seeds powder as a natural filling material were proposed as (NFRPC). Effect of different parameters on the tribological behavior of the proposed composite is studied. The proposed variables are; applied normal load, sliding speed, sliding distance and the percentage of filler contents. Pin on Disk tribometer was designed and constructed for the tribological measurements. Friction coefficient and rate of wear for the proposed composites have been obtained. The results show that; the coefficient of friction for polyester composites filled with date seed powder decreases by 15% with increase of filler under high contact pressure, beside the increase of velocity increases friction coefficient up to 10%. Rate of wear decreases to 10E-5 gm-1 with increase of date seed filler up to 10% under low contact pressure and low sliding speed, but; unfortunately, continuous increases of date seed filler from 15% to 25% decrease the resistance of wear for proposed composites under high contact pressure and high sliding speed. There is a significant effect of the applied load (contact pressure) and sliding velocity on the wear rate of polyester composite filled with date seed.

Steel dies used in hot extrusion of copper failed after several extrusion cycles (2-5 tons of extruded material). In the extrusion process the die is subjected to high temperatures and stresses the failure mechanisms was plastic deformation. Industry considers new die materials, such as Inconel 718. In this research it was shown that during production using an Inconel 718 die one can extrude 8 times more material (approx. 40 tons). After the extrusion of 40 tons of copper small cracks and plastic deformation on die aperture are seen. The die was discarded and used to investigate die failure mechanisms. By using different investigation methods (optic and scanning electron microscopy, hardness and microhardness tests) microstructure changes were observed. This research was done in the collaboration of Politehnica University of Bucharest, Romania and S.C. LAROMET S.A. (a manufacturer of copper and copper alloys).

This paper describes the characteristics of organic solar cell. Several characteristics impact on the conversion efficiency of organic solar cells was discussed. Recently, organic solar cells are attracting a lot of attention due to flexibility, low cost, light weight and large-area applications, and significant improvement in the power conversion efficiency. But the efficiencies of organic solar cells are still lower than crystal silicon solar cells. A circuit model of the solar cell provides a quantitative estimate for losses in the solar cell to interpret the characteristics of the solar cell. However, compared with inorganic solar cells, organic solar cells are lack of a three-dimensional crystal lattice, different intramolecular and intermolecular interactions, local structural disorders, amorphous and crystalline regions, and chemical impurities. Therefore, an appropriate model is represented in the paper.

Advanced makers, looking to stay focused in the business sector, depend on their assembling architects and creation work force to rapidly and adequately set up assembling procedures for new items. Taguchi Parameter Design is an intense and effective technique for enhancing quality and execution yield of assembling procedures, along these lines a capable apparatus for meeting this test. This proposition examines an examination concerning the utilization of Taguchi Parameter Design for upgrading surface roughness produced by a CNC lathe machine. Control parameters being considered in this proposal are speed, feed rate and depth of cut. After tentatively turning example work pieces utilizing the chose orthogonal cluster and parameters, this study anticipated that would create an ideal mix of controlled parameter for the surface roughness.

The adverse effect associated with the surge in uses of non-biodegradable plastic products include the blockage of drains, suffocating some animal life, who accidentally take them as food, grounds impermeable to water and several other hazards. The need then arises to finding a safe means converting these plastic waste products into other useful and harmless items. The method adopted involves the collection of the plastic materials from trenches, drainages, streets, dump sites and from eateries around Ogbomoso metropolis. These were sorted and washed before the Shredding Process was carried. Melting of the Shredded Plastics and poured into a dimensioned wooden mould and Cured for some days. It could be shown from the crushing test that the conventional tiles fail under slight heavier loads of 34 kN as comparable to the 29 kN failure load of the composite tiles. However the water absorption test has no effect on both the conventional and the composite tiles respectively. Furthermore, the flammability test carried out on the conventional tiles shows a slight change as compared to the composite tiles which split under the effect of flame. Moreover the composite tiles recorded a higher value than that of the conventional tiles. The tests show that the composite floor tiles are cheaper, durable, and affordable as compared to the ceramic tile. Hence, the performances of the composite floor tiles though are a little less than that of the commercial ceramic floor tiles yet appear a reasonably good substitute at more reasonable rate.

By using the principle of relativity (first postulate), together with new defined nature of the universal speed (our second postulate) and homogeneity of time-space our third postulate, we derive the most general transformation equations of relativity in one dimensional space. According to our new second postulate, the universal (not limited) speed c in Armenian Theory of Special Relativity is not the actual speed of light but it is the speed of time which is the same in all inertial systems. Our third postulate: the homogeneity of time-space is necessary to furnish linear transformation equations. We also state that there is no need to postulate the isotropy of time-space. Our article is the accumulation of all efforts from physicists to fix the Lorentz transformation equations and build correct and more general transformation equations of relativity which obey the rules of logic and fundamental group laws without internal philosophical and physical inconsistencies.

Indium has gained significant attention in the semiconductor industries due to its unique thermal and optical properties. The objective of this research was to investigate the influence of the biofield energy treatment on the atomic, physical and thermal properties of the indium. The study was performed in two groups (control and treated). The control group remained as untreated, and treated group received Mr. Trivedi’s biofield energy treatment. Subsequently, the control and treated indium samples were characterized by the X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR) spectroscopy. The XRD diffractogram showed the shifting of peaks toward higher Bragg’s angles in the treated indium sample as compared to the control. The crystallite size of treated indium sample were substantially changed from -80% to 150.2% after biofield energy treatment, as compared to control. In addition, the biofield energy treatment has altered the lattice parameter (-0.56%), unit cell volume (-0.23%), density (0.23%), atomic weight (-0.23), and nuclear charge per unit volume (1.69%) of the treated indium sample with respect to the control. The DSC showed an increase in the latent heat of fusion up to 3.23% in the treated indium sample with respect to control. Overall, results suggest that biofield energy treatment has substantially altered the atomic, physical, and thermal properties of treated indium powder. Therefore, the treated indium could be utilized in thermal interface material in semiconductor industries.

Dissimilar welding of 316L stainless steel-low carbon ferritic steel joints made using pulsed Nd: YAG laser beam. The laser spot symmetrically focused on the butt joint and offset-ted by 2 μm to stainless steel to obtain the good quality of dissimilar weld. A three dimensional finite element based model developed using comsol code to simulate welding process for these two different laser spot positions. Thermal profile, isothermal surface, and deformation of the dissimilar joints simulated to investigate the temperature distribution across the butt joints. The temperature distribution estimated across the dissimilar joint analytically. The estimated and predicted results exposed the bead width and heat affected zone in dissimilar joints. These results were compared with experiment found that has very close association with each other.

In this work utilizing sol-gel process we synthetized Ag/TiO2-SiO2 nanomaterial containing 0.1, 1.0, 5.0, and 10% weight of silver. The samples were characterized with infrared (FTIR), Ultraviolet-visible (UV-VIS), Scanning Electron Microscopy (SEM), Z-Sizer and N2 adsorption-desorption. The Nanoparticles (NPs) were tested in ten different types of strains by studying Kirby-Bauer susceptibility. The results show that the nanoparticles exhibit antimicrobial activity at all concentrations. We determinate de Minimum inhibitory concentration (MIC) which shown that Candida albicans ATCC 10231 and Staphylococcus epidermidis NRS 101 showed the highest sensitivity to silver NPs at concentrations of 10 and 1%.