Electron microscopic study of worn PAN-pitch based carbon-carbon composite Original Research Article

Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM)/microdiffraction techniques have been used to characterize the microstructure of a polyacrylonitrile (PAN)-based fiber-reinforced mesophase pitch-based matrix carbon-carbon (CC) composite before and after sliding at two different speeds. Emphasis was placed on the study of wear-induced amorphization and graphitization phenomena. The results indicated that both phenomena were observed in the debris film of the high speed-slid specimens. The wear-induced amorphous film was identified by the diffuse rings/halos in SAD patterns, while the numerous graphitized particles were confirmed by bright and dark field images, SAD and microdiffraction patterns. The wear-induced graphitization phenomenon suggests that the asperity temperatures should be high enough for graphitization to take place at local spots, particularly in the more graphitizable pitch-based matrix.