Influence of rare-earth oxide additives and SiC nanoparticles on the wear behaviour of Si3N4-based composites at temperatures up to 900 °C

Influence of various rare-earth (RE) oxide additives and SiC nanoparticles on the wear behaviour of Si3N4-based composites has been investigated under dry sliding conditions at temperatures up to 900 °C. A significant influence of both the crystalline character of the grain boundary phases as well as the location of SiC nanoparticles on the wear resistance of the materials has been observed. The wear resistance of the materials with crystalline grain boundary phases increased with decreasing RE3+ for the monoliths as well as the composites due to the higher viscosity and refractoriness of the secondary phases. The presence of the intergranular SiC particles results in lower specific wear rate of composites in comparison with the monoliths. The composites doped with the additives with lower ionic radius such as Lu, Yb and Y exhibited the lowest specific wear rate up to 700 °C indicating the best possibility of the application of such materials.