The influence of Cr on the tribological properties of in-situ TiC/Ni composites in wide temperature range

To investigate the influence of Cr on the tribological properties of in-situ TiC/Ni-based composites in a wide-temperature, the study prepared TiC/Ni composites with Cr contents of 0wt.% and 15wt.% by pressureless reaction sintering. The phase composition, microstructure, hardness and tribological properties from room temperature to 800℃ were systematically analyzed. The friction test condition is grinded by Al₂O₃ ball under 10 N load for 30 min. It was found that the TiC/Ni composites mainly consist of TiC and Ni. The introduction of 15wt.% Cr promotes the formation of Cr₇C₃ and Cr₂₃C₆ phases in the composites, which refines the TiC particles through the grain boundary pinning effect, thereby increasing the hardness of the composites from 623.8 HV to 996.8 HV. At room temperature, the composite with 15wt.% Cr exhibits negative wear rate due to the higher hardness, and the primary wear mechanism is abrasive wear and slight oxidative wear. At 600~800℃, the addition of 15wt.% Cr enables the formation of continuous tribolayer with microcracks on the composite surface, which is made up of NiO, TiO₂, NiTiO₃, SiO₂ and Cr₂O₃. The wear rate at 800℃ reduces from 14.03×10⁻⁶ mm³/(N·m) to 7.19×10⁻⁶ mm³/(N·m) by adding 15wt.% Cr. Therefore, the addition of suitable content of Cr can enhance the wide temperature range tribological properties of TiC/Ni composites and improve their service life.