Study of wear resistant MoSi₂-SiC composites fabricated by self-propagating high temperature synthesis casting

MoSi₂ composites with 10, 15 and 20 wt.% SiC were fabricated as wear resistant materials by self-propagating high temperature synthesis (SHS) casting route. The composites were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM) with X-ray energy dispersive spectroscopy (EDS). Hardness, toughness and wear rate of the composites were measured. XRD examination showed that the composites mainly consisted of MoSi₂, SiC and Al₂O₃ phases. Content of Al₂O₃ was about 3 wt.% in the composites. Microstructures of the composites varied with the amount of SiC. Silicon carbide phase presented in the composites was in the term of large particles or short fibers depending on the amount of SiC presented in the composites. Cracks existed near interfaces of the large SiC particles and MoSi₂ matrix in composites with 10 and 15 wt.% SiC whereas they did not appear in composite with 20 wt.% SiC. Hardness and toughness of the composites increased with increase of SiC. Wear rate of the composites and its sensitivity to load dramatically decreased with SiC. Composite with 20 wt.% SiC had the best properties.