刹车速度对C／C复合材料制动摩擦性能的影响

在MM－1000型摩擦磨损试验上考察了碳布叠层结构的C／C复合材料在不同速度下的制动摩擦磨损行为，并用扫描电子显微镜观察分析了试样磨损表面形貌，结果表明：随着刹车速度的增大，摩擦系数增大，在20－25m/s速度范围出现峰值；当刹车速度增大至28－30m/s时，摩擦系数仍保持较高，体现了优良的高能摩擦特性；磨损量在低速时较小，当刹车速度大于15m/s，磨损量迅速增大，低速时磨损表面由一层薄的磨屑层所覆盖，当速度大于15m／s，大量的磨屑形成一层较厚的磨屑层，高速时由于剧烈的氧化和剪切作用，很多基质碳被氧化剥落，炭纤维被磨断、拔出，使磨损增大。

Effect of Braking Speed on Friction Properties of C/C Composite Braking Pad

The friction and wear behavior of C/C composites with carbon cloth laminated structure was investigated on an MM 1000 test rig at different braking speeds. The worn surfaces of the samples were examined with a scanning electron microscope. It has been found that the friction coefficient increases with increasing braking speeds and reaches to maximum in the speed range of 20~25 m/s. When braking speeds increase to 28~30 m/s, the friction coefficient still remains high value, indicating that it might be a candidate as the braking pad of excellent high energy friction performance. The wear rate is much small at low braking speed and rapidly increases with the braking speed rises above 15 m/s. At a relatively low braking speed, the worn surface of the composite was covered with a thin debris layer. When the braking speed rose over 15 m/s, a thicker layer composed of the wear debris was formed on the worn surface. Such a wear debris layer is liable to remove under normal and shearing stress, thus a relatively higher wear rate is observed at higher braking speed. In the meantime, severe oxidation also contributes to increase the wear rate of the composites at higher braking speed, accompanied by the oxidation and spalling of carbon matrix and carbon fibers.