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

Carbon fiber reinforced carbon and silicon carbide composites (C_f/C-SiC) have garnered substantial attention due to their superlative mechanical properties at elevated temperatures. In the present study, the tribological properties of 2.5D C_f/C-SiC against silicon nitride under dry friction over a wide temperature spectrum, ranging from room temperature to 800 °C, are studied by a pin-on-disc tribometer, and the microstructure is characterized by 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 ℃, the friction coefficient demonstrates a clear increase with rising 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 ℃, 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 ℃, 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 tribological behaviors and wear mechanism of C_f/C-SiC at elevated temperatures.