Effect of applied load on the dry sliding wear behaviour and the subsurface deformation on hybrid metal matrix composite

In this study, a new processing technique, friction stir processing (FSP) was used to incorporate SiC and MoS2 particles into the matrix of an A356 Al alloy to form surface hybrid composite. The tool rotation rate was changed from 630 to 1600 rpm and a tool tilt angle of 3 was applied. Higher tool rotation rate was found to causes a more uniform dispersion of reinforcing particles and thus, decreases particles clustering. Dry sliding wear tests were conducted using a pin-on-disc machine. The subsurface deformation was assessed as a measure of variation in microhardness along the depth normal to the cross-section of the worn surface. It was found that the wear resistance of the processed samples improved significantly as compared to that of the as-cast alloy. Microstructural analysis showed that a MoS2 rich layer on the top of worn surface helped to decrease the plastic deformation in subsurface region and alleviate severe wear. The improvement in wear resistance of surface hybrid composite compared to that of the as-cast alloy was found to be more pronounced under higher applied loads. (C) 2012 Elsevier B.V. All rights reserved.