SiC wear resistance coating with added Ni, for carbon/carbon composites

To improve the tribological performance of carbon/carbon (C/C) composites at high temperature, a SiC coating with added Ni (SiC–Ni coating) was prepared by pack cementation. Dry sliding tests were conducted at different temperatures, and related microstructure and mechanical characteristics were investigated by scanning electron microscopy, X-ray diffraction, nano-indention, and scratch tester. The SiC–Ni coating is mainly composed of SiC and NiSi2, and the adhesion between coating and substrate is reliable. The friction coefficient of SiC–Ni coating is about 0.35 at 25 °C, and the predominant wear mechanisms are micro-cutting and plastic deforming. Severe adhesion wear occurs at 600 °C which results in high friction coefficient. However, the SiC–Ni coating exhibits self-lubricating properties at 800 °C. A dense film (consisting of silica and nickel oxide) spreads on the wear track of SiC–Ni coating at 800 °C. This film reduces the friction coefficient effectively and enhances the wear resistance of the coating.