Study on the worn surfaces of C/C composites at various braking velocities

The friction and wear properties of carbon/carbon (C/C) composites with a rough laminar (RL) matrix carbon at various braking velocities were tested by using the MM-1000 laboratory scale dynamometer. The microstructures and morphologies of the worn surfaces were investigated by using micro-Raman spectroscopy and SEM respectively. The results are as follows. The C/C composite with an RL matrix carbon possesses excellent friction-velocity characteristics. The effects of braking velocity on the friction coefficient can be attributed to that on the temperature elevation of the worn surface as well as the thickness and continuity of the friction film. At 5 m/s braking velocity, the friction coefficient is low due to the absorption of hydrosphere and no continuous friction film formed; the friction coefficient reaches the peak at 10 m/s due to the desorption of hydrosphere and multi-layer thick friction film formed. With the increase of braking velocity, the thickness of the friction film decreased, resulting in the drop of friction coefficient wear rate values. When the braking velocity is above 25m/s, the temperature elevation of the worn surfaces results in the increase of mass loss by oxidation and linear wear losses, and the friction coefficient also slightly declines (0.3).