Unstable feature and tribological performance transition of C_f/C–SiC under elevated temperatures

Carbon fiber-reinforced carbon and silicon carbide (C_f/C–SiC) composites have garnered substantial attention because of their superior mechanical properties at elevated temperatures. In the present work, the tribological properties of 2.5D C_f/C–SiC against silicon nitride under dry friction over a wide temperature range, ranging from room temperature (RT) to 800 °C, are studied with a pin-on-disc tribometer, and the microstructure is characterized via a variety of methods. The results underscore that 600 °C marks a pivotal juncture where the tribological properties of C_f/C–SiC undergo a notable shift. Below 600 °C, the friction coefficient clearly increases with increasing temperature, paired with minimal wear. For this temperature range, the main wear mechanisms are minor oxidation wear and slight abrasive wear. In contrast, above 600 °C, a slightly lower, fluctuating plateau is observed in the friction coefficient. This is attributed to the accumulation of wear debris, the cyclical formation and breakdown of the friction film, and the softening of the friction surface. For temperatures above 600 °C, the wear mechanism transitions into a state characterized by the concurrent presence of adhesive wear, abrasive wear, and severe oxidative wear. This study provides an in-depth understanding of the tribological behavior and wear mechanism of C_f/C–SiC at elevated temperatures.