Enhancement of mechanical and sliding wear properties of functionally graded Al–12Si–Cu composites

Abstract

Functionally graded (FG) Al–12Si–Cu composites reinforced with Boron Carbide (B4C), Silicon Carbide (SiC) and Zirconia (ZrO2) respectively were fabricated through horizontal centrifugal casting. Hardness analysis along the radial direction revealed an improvement in hardness from core to outer periphery which was in accordance with the observed gradient microstructure. Comparative wear analysis at outer and inner layer of all composites revealed better wear performance at outer layer of all FG composites, with outer layer of Al/ZrO2 composite exhibiting superior performance. With increasing applied load and sliding distance, an increase in wear rate is observed whereas with increasing sliding velocity, wear rate decreases. Worn morphology analysis of FG Al/ZrO2 composite revealed mild to severe wear transition at high loads, matrix cracking and mild delamination wear at low sliding velocity and a combination of tribo-oxidative layer, abrasive wear existed at higher velocities. Of all fabricated FG composites, Al/ZrO2 composite is well suited for dry sliding applications.