Aluminum matrix composites reinforced with reduced graphene oxide (rGO) and hybrid of carbon nanotube (CNT) and rGO are fabricated by solution coating powder metallurgy process. The hardness, wear resistance and coefficient of thermal expansion (CTE) of the reinforced aluminum composites and the associated microstructural changes with rGO range (0.2-0.6 wt. %) and hybrids of 0.2 wt. % CNT-rGO at different ratios have been investigated. The intensive microstructural observations show that rGO is adsorbed on Al particles and uniformly distributed in the Al matrix composites. The hardness values of the composites increase significantly with rGO reinforcement exhibiting the maximum hardness at 0.4 wt. % rGO. Compared with the hybrid composites CNT-rGO/Al counterparts fabricated by the same route and wt. percent of 0.2, the hardness values in the hybrid CNT-rGO increase considerably. Similar to the hardness, the results of wear tests also exhibit corresponding variation in the values of the wear rates. The improvement in the wear resistance of the hybrid CNT-rGO/Al composite is pronounced in this work. Whereas the rGO reinforcements decrease significantly the wear rate of the aluminum-base by 98%, the wear resistance of the corresponding hybrid CNT-rGO is significantly higher than that of the preceding composites. Maximum CTE reduction of 28% was recorded for hybrid CNT-rGO (1:1) reinforced composite.
The bullet-resistant vest (bullet proof vest) is an important accessory to absorb impact energy and stop bullets from penetrating the body. In the present work a sandwich composite structure was designed from different sequential layers of, twinning induced plastic (TWIP) steel, polypropylene – polyethylene (PP-PE) polymer and water for bullet proof vest application. Owing to the difficulty in experimentally testing materials for ballistic impact application, a finite element – smoothed particle hydrodynamic (FE-SPH) coupled simulation was applied for analyzing the impact characteristics of the proposed composite structure. Different structural layers of the composite are simulated to select the most effective thickness of steel/polymer/water layers in energy absorption and penetration prevention. The simulation results displayed that the optimum thickness of the layers are 2 mm steel/20 mm water/2 mm steel , which is able to stop a 9 mm bullet travelling at 360 m/s with less than 10 mm displacement of the inner surface of the composite. This composite is promising and has a great potential in fabrication of effective and light weight bullet proof vest with less expensive materials.
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