Wear mechanism and three-phase synergistic effect of self-mated SiC/Si/graphite composites in unlubricated sliding

Abstract

With the aim of applying SiC/Si/graphite composites as thrust-bearing pads and runners under conditions of dry friction start-stop cycles and a transient absence of lubrication, the tribological behaviors of self-mated SiC/Si/graphite composites were investigated using pin-on-disc tribology tests under various applied loads and sliding speeds without lubricants. The results show that the friction coefficient values range between 0.10 and 0.21, and the total specific wear rates of the discs and pins are below 9.5 × 10⁻⁶ mm³/N·m. When the flash temperature is greater than 1500 °C, the main wear mechanism changes from two-body abrasive wear between SiC and graphite to oxidation wear of SiC and Si, three-body abrasive wear and adhesive wear of graphite and tribological film. The synergistic effects of Si, SiC, and graphite on wear reduction and tribological film formation were also elucidated.