针刺毡C/C复合材料磨擦制动压力和速度特性

用模拟刹车制动的摩擦试验机,研究探讨了一种针刺毡结构C/C复合材料在不同制动压力和制动速度下的摩擦磨损性能,并用扫描电子显微镜对摩擦表面进行了观察和分析。摩擦磨损机理由磨屑经挤压、剪切堆积在表面形成的磨屑层所决定。在5m/s制动速度或静态条件下,表面温度低(<150~200℃)吸附水气未脱附,其润滑作用导致了较低的摩擦系数值;当制动速度达到10m/s,摩擦使表面温度升高,达到了吸附水气脱附温度,引起摩擦系数急剧升高,达到了最大;此后,随制动速度及表面温度的继续升高,磨屑层间剪切强度降低,导致摩擦系数随之下降。在较高制动速度下,该种材料仍能保持较高的摩擦系数,显示出优良的高温高能摩擦性能。

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.