FRICTIONAL AND WEAR BEHAVIORS OF THE C/C COMPOSITE FROM A NEEDLED FELT AT DIFFERENT BRAKING PRESSURES AND SPEEDS

Frictional and wear behaviors of the C/C composite from a needled felt were investigated at different pressures and speeds by simulating the aircraft braking with pairs of circle samples. The rubbing surfaces were examined with SEM. The braking speeds increased from 0 in step of 5 m/s. The mechanisms of friction and wear depend on the wear debris film covered on the rubbing surfaces. At a low speed of 5 m/s or at static the friction coefficient is very low due to the lubricating of absorbed water vapor on the surface. When the speed increases to 10 m/s, the surface temperature will be high enough to absorb the absorbed water vapor by the frictional heating, so the friction coefficient can rapidly increase to the maximum. Then, with the further increasing of the braking speeds and the surface temperatures, the decrease of the inter-laminar shear strength of the wear debris film will result in the friction coefficient decreasing. But the friction coefficients will be high enough at high braking speeds, demonstrating its excellent high energy braking character.