Publication

Abstract : This study investigates the tribo-mechanical behaviour of centrifugally cast as-cast and T6 heat-treated A359/TiB2 functionally graded composite (FGC). Linear reciprocating wear tests were performed on both composites under varying sliding distances (500-1500 m) and loads (15-55 N). A gradient TiB2 particle distribution was observed from the outer to inner periphery (6, 2 and 1 wt % respectively) of the as-cast FGC, whereas the heat-treated FGC displayed spheroidised eutectic Si particles throughout the cross-section. This led to superior mechanical properties for the outer zone of heat-treated composite (188.7 HV, 286.1 MPa) when compared to the as-cast outer zone (147.5 HV, 243.4 MPa). The heat-treated composite had displayed enhanced tribological properties under reciprocating wear tests, and it was observed that both composites had exhibited a proportional increase in wear rate with increasing experimental parameters and with graded particle concentration, whereas the coefficient of friction (COF) was independent of the wear parameters and directly dependent on the TiB2 concentration. The wear mechanisms observed were adhesive and minor delamination under high and low load conditions. The mechanically mixed layer presence was confirmed through wear debris analysis, due to which the COF was observed to be constant after 1250 m of sliding distance.