Surface effect on braking behavior of PAN-pitch carbon-carbon composite

This work studies the braking (simulated-stop) behavior of a polyacrylonitrile (PAN)-pitch carbon-carbon composite under different surface conditions. The results indicate that broken-in (BI) specimens exhibited much higher friction coefficients and wear than those of aspolished (AP) specimens under the same braking conditions. The specimens braked from higher speed always suffered higher wear either due ro their higher friction coefficients or longer braking times. The friction behavior of the present composite was found most sensitive to the debris morphology. The friction behavior of RI specimens, which had undergone a transition during the BI treatment, was more complex and harder to predict than that of AP specimens, which did not undergo transition before or during braking. The severe structural damage on the BI/2000 surface, which could nor be mended (a stable lubricative debris layer could not be developed), resulted in an unstably high friction surface and large wear.