Microstructural and mechanical properties of pressureless sintered high-wear-resistant SiC composite materials

The microstructural and mechanical properties of pressuless sintered SiC-based composite materials with Al or Cu addition (0-10 wt.%) were studied. The introduction of 1-2 wt.% of metals to the SiC results in appreciable porosity decreases from 31 to 19 +/- 1%. Moreover, metallic aids considerably affects the phase composition of the materials. Cu suppresses the formation of mullite. In contrast, Al increases the content of the moissanite phase in the final material because of a thick oxide film on the surface of silicon carbide. However, metal content does not steadily increases due to the melt removes from the open pores during the sintering process. The hardness of the composite material mainly depends on the moissanite phase content, which could be enhanced by metal additives. Developed composite materials have up to 50 and 3 times greater resistance to abrasive and cavitation wear correspondingly than the original porous SiC.