Wear behaviour and microstructural changes of SiCw-Al composite under unlubricated sliding friction

Abstract

The transition of wear mechanisms and the microstructural changes of the SiCw-Al composites under unlubricated sliding friction were studied by X-ray diffraction, scanning electron spectroscopy and transmission electron spectroscopy techniques. The results show that with the increase of normal load and/or speed during dry sliding, the wear behaviour of the SiCw-Al composites transforms from mild wear to severe wear and then to seizure. The mild wear is characterized by mild oxidation and severe oxidation assisted slightly by adhesion, while the severe wear is dominated by abrasion or adhesion and delamination. Plastic deformation occurs in the surface layers of the tested specimens and the SiC whiskers realign along the sliding direction in the deformation layers. Oxide, β-Al 2O 3, forms on the surfaces; matrix metal grains fragmentation, fracture and fragmentation of SiC whiskers occur in the subsurfaces. Cracks usually initiate along whisker-matrix interfaces and propagate into the matrix.