Optimization of dry sliding wear behavior of Si3N4 and Gr reinforced Al–Zn–Mg–Cu composites using taguchi method

Abstract

The sliding wear behavior of stir cast silicon nitride (Si3N4) and graphite (Gr) reinforced Al–Zn–Cu–Mg (Al alloy) matrix composites were investigated under dry conditions. Al alloy/1 wt.% Si3N4 composite, Al alloy/1 wt.% Si3N4–xGr hybrid composites (x = 1.5 and 3% Gr by weight) were separately developed to examine their wear behavior. Microstructure and EDS characterization were used to identify the reinforcement (Si3N4 and Gr) in casted composites. Experimental design with L–27 orthogonal matrix array was chosen to perform the wear experiments to examine the effect of various applied normal loads (15 N, 30 N, and 45 N) and sliding velocities (0.523, 1.047, and 1.57 m/s) at a constant sliding distance of 1000 m. Results reveal that the wear rate significantly decreased after adding 1.5 and 3 wt.% Gr in Al– Si3N4 composite and obtained a minimum wear rate for hybrid composites containing 3 wt.% Gr particles. ANOVA results revealed that load is the most dominating factor in wear rate, followed by sliding velocity and Gr content. The worn surface study observed lesser micro-cracks and pits in the hybrid composite containing 3 wt.% Gr compared to Al– Si3N4 composites. The uniform distribution of reinforcing particles in the Al alloy matrix was examined through SEM characterization of casted samples.