Friction surface structure of a Cf/C-SiC composite brake disc after bedding testing on a full-scale dynamometer

We have examined friction surface structure of a carbon ceramic brake disc tested on a full-scale dynamometer with microscopy techniques. The bedded friction surface is composed of two types of regions: transferred materials (TM) and SiC. The TM regions were formed through the deposition of wear debris into surface voids, followed by compaction and crystallite refinement during braking. A thin friction layer (FL) was developed on top of TM and SiC regions with nano-sized copper/iron oxide crystallites as the primary constituent. Analysis shows that debris generated from pad is the main source of TM and FL. No evidence shows chemical diffusion bonding between TM and composite constituent. On silicon carbide surface, dislocations were activated as the sources of surface fracture.