Effect of Resin-Derived Carbon on the Friction Behavior of Carbon/Carbon Composites

Three different C/C composites with rough laminar (RL) pyrocarbon, RL pyrocarbon with added resin-derived carbon, and pure resin-derived carbon have been evaluated and tested for friction performance. A laboratory dynamometer was used to simulate different braking speeds utilizing a single stator and rotor pair. The morphologies and microstructures of the raw materials, wear surfaces, and wear debris at different braking levels were observed by polarized light microscopy, scanning electron microscopy, and transmission electron microscopy. The results have shown that the friction coefficients of the three C/C composites display the same characteristics with increasing braking speed. They increased to a maximum value at medium braking speed and thereafter decreased with increasing braking speed, and their mean values under the same braking conditions were similar. The C/C composite with pure resin-derived carbon showed the highest loss due to wear under all conditions, while the C/C composite with the RL pyrocarbon showed the lowest loss. Resin-derived carbon in C/C composites does not have a significant effect on the friction coefficient, but the wear rate increases greatly with increasing resin-derived carbon content. Wear debris is composed of flocculent particles with polycrystalline structure, along with the matrix carbon, which is worn off directly from the composites.