Progress in tribological research of SiC ceramics in unlubricated sliding-A review

Silicon carbide ceramics have many excellent properties, such as high melting point, high strength, high thermal conductivity, high hardness, high stiffness, good chemical resistance, good electrical conductivity and remarkable wear resistance. Therefore, SiC ceramics are useful for various tribological applications. Nevertheless, SiC ceramics usually exhibit poor friction characteristics under unlubricated sliding contacts, which can greatly deteriorate the durability and reliability of a tribosystem. In this work, the tribological research progress of SiC ceramics was summarized based on microstructural characteristics, self-lubrication methods, surface characteristics and external factors. First, tribological performance of SiC ceramics can be improved by controlling microstructural characteristics, such as reducing grain size of SiC ceramics, acquiring elongated SiC grains, reducing the content of grain boundary/intergranular phase, crystallizing amorphous grain boundary phases, hardening intergranular phases, controlling cracks propagation way. Second, good self-lubrication property for SiC ceramics can be obtained by annealing heat treatment, adding the secondary phase or producing porous SiC ceramics. Third, tribological performance of SiC ceramics can be improved by proper surface processing or surface modification, such as proper roughness, surface texture or coating technology. Fourth, tribological performance of SiC ceramics is affected by various external factors. Besides, the research trends of SiC ceramic tribology in future were proposed. This work aims to provide some reference for the design of SiC ceramics with high wear resistance and low friction.