Effects of C content on the microstructure, mechanical and tribological properties of TiAlSiCN coatings.

The effects of C doping content on the microstructure, mechanical and tribological properties of TiAlSiCN coatings prepared by ion plating are systematically investigated. The results show that the grain is refined with the C content increases to 17.22 at.%, and the (111) and (200) planes present competitive growth, the high C content promotes the preferred orientation of the (200) planes. The hardness of the coating shows a tendency to increase first and then decrease, the coating with C content of 8.15 at.% achieve the highest hardness, while the elastic strain resistance H/E value decreases monotonically. Moreover, it is found that the amorphous carbon (a-C) structure is precipitated with C content above 12.51 at.%. The wear mechanism of the coating against the Si 3 N 4 counterpart is adhesive, and the coefficient of friction (COF) of the coating decreases from 0.4 to 0.2. Thereinto, the reduction in COF is related to the Hertzian contact area as C content below 8.15 at.%. The COF further reduction is attributed to the generation of graphite lubricated structure. However, the wear rate shows first decrease and then increase. Therefore, the preferential C doping content can improve the mechanical and tribological properties of the coatings. • The research revealed that C content has significant effect on the microstructure and tribological properties of TiAlSiCN coating. High C content promotes the preferred orientation of the (200) planes. • The amorphous carbon (a-C) structure is precipitated with C content above 12.54 at.% • The lower COF is related to the Hertzian contact area decrease and the generation of graphite lubricated structure. [ABSTRACT FROM AUTHOR]