Effect of surface condition on tribological behavior of PAN-CVI based carbon-carbon composite

This work studied the braking (simulated-stop) behavior of a PAN-CVI-based carbon-carbon composite under different surface conditions. The results indicate that, under the same braking condition, the broken-in (BI) composite exhibited a higher friction coefficient and wear than an as-polished (AP) composite. The composite braked from 2000 rpm always had a larger weight loss and shorter stopping time than from 1400 rpm due to its much higher friction coefficient. Under non-transitional, stably low friction coefficient condition (AP/ 1400 and BI/1400), the sliding speed decreased linearly with time during the entire braking period. For transitional AP/2000 and BI/2000 tests, the deceleration rate varied according to its friction coefficient level. Tribological behavior of the composite was sensitive to, and could be largely interpreted from, the worn surface morphology. A smooth debris film was formed on non-transitional AP/1400 and BI/ 1400 surfaces, while the transitional AP/2000 and BI/2000 surfaces exhibited a mixed types II-III morphology. Much lesser and smaller wear particles were generated from non-transitional AP/1400 and BI/1400 tests than from transitional AP/2000 and BI/2000 tests.