Dry sliding wear behavior of Mg/SiC composites

Mg/SiC composites containing 0-20 vol% SiC particles were fabricated by powder pressing and hot extrusion. The effects of SiC content on density, microstructure, hardness and wear behavior of pure magnesium were studied. Wear tests were conducted using a pin on disk configuration against a hardened tool steel counterface under the loads of 6, 12 and 18 N at a constant sliding speed of 0.12 m/s at room temperature. The microstructural studies using optical microscopy revealed a reasonably uniform distribution of SiC reinforcing particles within the magnesium matrix. The dominant wear mechanisms were determined by studying the wear surfaces and debris using a scanning electron microscope (SEM) equipped with EDS detector. Results showed that coefficient of friction increased with increasing SiC content at any applied load. While increasing the normal load resulted in decreasing of coefficient of friction, it increased the wear rate. The lowest wear rate was attained in the composites reinforced with only 5 vol% SiC particles regardless of the normal applied load. Microscopic studies of the worn surfaces revealed severe and mild abrasion as the main wear mechanisms controlling the sliding of pure Mg and Mg/5SiC composite, respectively. However, it was confirmed that delamination predominated for Mg/20SiC composites particularly at higher normal loads.