Effect of Carbon Nanotube (CNT) Content on the Hardness, Wear Resistance and Thermal Expansion of In-Situ Reduced Graphene Oxide (rGO)-Reinforced Aluminum Matrix Composites

Abstract

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.