The influence of alumina on mechanical and tribological characteristics of graphite particle reinforced hybrid Al-MMC

Abstract

We consider the influence of alumina (Al2O3) particles on mechanical and tribological properties of aluminum hybrid metal matrix composites (MMC). Various weight fraction of Al2O3 (5, 10 and 15%) and constant weight fraction of graphite (5%) were used to fabricate composites by stir casting method. The effect of Al2O3 content on hardness, density and specific wear rate is evaluated. A wear test was performed using central composite design matrix on a pin-on disc apparatus at room temperature for constant sliding distance of 1000 m. The sliding speed, load and weight fraction of Al2O3 were the process variables. The results show that the hardness and density increase with increase in Al2O3 content. From the analysis of variance (ANOVA), load is the dominant factor that affects the specific wear rate of hybrid composites followed by speed and weight fraction of Al2O3. Based on desirability approach, the improvement in the wear resistance of the composites became more prominent at high speed, high load and high weight fraction of Al2O3. The worn surface of the pin was examined using scanning electron microscope (SEM) which indicates that the wear mechanism of composites is mostly abrasive wear followed by oxide wear.