High-speed tribological behaviour of a carbon/silicon-carbide composite

Increasing attention is being paid to carbon-fibre/SiC-matrix composites (C/SiC) for their friction and wear performance because the carbon-fibre reinforcement enables a significant reduction in the coefficient of friction through self-lubricating properties. This study was performed by using a C/SiC composite at high-speed (15 m s−1). Two distinct types of tribological behaviour, as a function of the rubbing pin features (100Cr6 or alumina), were found. Analysis of both the surface degradation and velocity adaptation mechanisms has made it possible to establish the major role of debris trapped in the contact zone. The wear debris from the 100Cr6-C/SiC pair is a heterogeneous layer adhering strongly to the friction track. Consequently, the velocity adaptation is a direct effect of the shearing of the transfer layers and fracturing of bulk materials, resulting in severe wear. In contrast, with an alumina-C/SiC pair, wear particles are finely ground owing to the fact that they remain for a long time in the contact zone. The velocity adaptation here mainly occurs through debris rolling and shearing within the powder bed, thus resulting in reduced wear.