MECHANICAL AND TRIBOLOGICAL BEHAVIOUR OF GRAPHITE- REINFORCED ALUMINIUM MATRIX COMPOSITES

In this work, mechanical and tribological behaviour of AA7075/Al2O3/graphite hybrid composite was studied. Pin-on-disc machine was used for the conductance of the wear test. The composites with 2-8 wt.% Al2O3 particles were processed by conventional liquid casting method. For the hybrid composite, 5 wt.% graphite were commonly added to the base alloy. The hardness of the composites was measured using a Vickers hardness tester and their tensile strength was measured by an universal testing machine (UTM). Scanning electron microscopy (SEM) was used to analyse worn surfaces of samples. It was found that an increase in Al2O3 content reduced the coefficient of friction up to 6 wt.% and thereon slightly increased. But this effect was reverse in hybrid composites and AA 7075 / Graphite composites. Hardness and tensile strength of composites increased with increasing Al2O3 content in both cases. The wear rates for both composites and hybrid composites were dependent on Al2O3 content in the alloy. Al/Al2O3 composites containing 6 wt.% Al2O3 exhibited superior wear properties over the base alloy, and hybrid composites.