Table of Contents - Volume 20 Number 2

Tribological behavior of powder metallurgically processes AlSi-MWCNT functionally graded materials was apparatus with pins on discs was examined. Using a Taguchi design of experiments, the signal-to-noise ratio, the analysis of variance, and an orthogonal array were all used to determine the best testing parameters. Analysis revealed wear loss occurs due to increase in load and sliding distance and reduced with MWCNT increased content in FGM. The composites with 1wt% of FGM exhibited both excellent wear resistance and friction coefficients. Wear mechanisms help in understanding the morphology of worn surfaces. The wear mechanism is dictated by delamination layer and other oxide layers. Overall, the findings showed that AlSi-MWCNT functionally graded materials are regarded as remarkable materials in industries where wear-resistant components are crucial, such as aerospace and automotive engineering.

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Nanocomposites of natural rubber (NR) with reduced graphene oxide (rGO) were prepared by varying their ratios intending to improve the electrical and mechanical properties of natural rubber. rGO was prepared through oxidation and subsequent reduction of high purity Sri Lankan vein graphite. The prepared nanocomposites were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. The SEM images viewed a uniform homogeneous surface of the nanocomposite while FTIR and XRD spectral signatures substantiated its chemical functionalities and structural traits respectively. Mechanical properties such as tensile stress & strain, elongation at break, hardness, Young's modulus, and strain of the nanocomposite, were also investigated. Here the electrical conductivity was measured using the two-probe method. The nanocomposite started conducting at 2% rGO in rubber and increased conducting with increasing rGO. The hardness of the composites continuously increased with increasing rGO in rubber. Despite the tensile strength and elongation at break, Young's modulus also increased with increasing the rGO percentage up to 1.5 % and was optimized at the particular ratio. The highest strength of 15.91MPa was obtained at 1.5% of rGO. A detailed property investigation of rGO/NR nanocomposite has not been reported previously for the best of our knowledge. Hence, the study expected to be well supportive for future industrial developments including electronics, electrical devices, batteries, capacitors, as well as in heavy equipment including aerospace and automobiles.

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The protection of XC100 steel against oxidation due to butane/propane combustion by the mean of nickel (Ni), Nickel-Silicon (Ni-Si), and Nickel-Silicon carbide (Ni-SiC) electrodeposited coatings is reported. Gravimetric and microstructural characterizations of coatings after direct exposure to the gas flame were conducted. The results show that Ni-SiC coating improves the protection against oxidation of the underlying steel XC100 by decreasing the rate of weight gain by about 20 times against 13 times for Ni due to the decomposition of SiC particles in the boundaries of the coaxial grains network. Besides, the preferential oxidation of silicon particles to SiO2 into the nickel matrix revealed by EDS-X analysis confers stability to Ni-Si coating although its catching of mass is slightly higher than that of Ni-SiC. The charge transfer resistance Rct and the oxide electrical resistance Roxide extracted from Electrochemical Impedance spectroscopy agreed with gravimetric and microstructural observations.

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Today's challenge is to produce a biodegradable materials for packing which can partially replace traditional plastic materials. Starch-based biodegradable plastics are less harmful to the environment and breakdown faster than regular plastics. The goal of this research was to produce and characterize a biodegradable film(BF) made from Sorghum bicolor (L.) starch and glycerol plasticizer. The produced film contained two amounts of Sorghum bicolor (L.) starch (5 g and 10 g) and three percentages of glycerol (25%, 30%, and 40%). The Sorghum bicolor (L.) and biodegradable glycerol-based plastic film had the lowest density, water absorption, and thickness swelling of 0.99 g cm^-3, 55.72%, and 10.72%, respectively. The tensile strength is maximum at 9.97 MPa and and elongation obtained is 23.84%. The Sorghum bicolor (L.) starch and glycerol-based biodegradable film decomposed by 69.23% after biodegradability testing of one week.

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The goal of propeller designers has always been to increase several settings to improve propulsion efficiency have been devised. One of the leading attractive propulsion systems is coupled contra-rotating propellers, which can be expected to significantly improve the open water efficiency with reduced rotational kinetic energy losses. The 3-Dimensional hydrodynamic contour of the coupled contra rotating propellers makes simulation with the highest rotational velocity of 2000rpm with an analytical structural design exceedingly challenging deformation must be less then 1mm. To analyze the propeller strength the Ansys FEM Simulation approach is applied. Static analysis is carried out with a Stainless Steel and has a component of strength analysis to guarantee the safety of the coupled contra-rotating propellers.

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The antimicrobial cotton fabric has been prepared by coating it with Ag treated with SDS(Sodium dodecyl sulphate) nanocoating and its antimicrobial properties have been tested. It is observed in the present study, that the nanocoating coated cotton fabrics have good antimicrobial properties. The coated cotton fabric showed an antibacterial activity value of 5.86 against Klebsiella pneumonia ATCC 4352 and that of 4.89 against Staphylococcus aureus ATCC 6538 when tested according to the JIS L 1902-2015 method.

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