不同制动速度下C/C复合材料摩擦面研究

采用MM-1000型摩擦磨损试验机测试了粗糙层基体炭C/C复合材料试样在不同制动速度下的摩擦磨损性能, 借助微区拉曼光谱和扫描电镜研究了试样摩擦面的结构与形貌。结果表明粗糙层基体炭C/C复合材料具有优异的摩擦速度特性。试样的摩擦系数和试验后摩擦面上碳原子的有序度无直接对应关系, 制动速度对摩擦系数的影响应归因于制动速度对摩擦面温升和摩擦膜厚度及完整性的影响。5m/s的低制动速度下, 试样因吸附水气摩擦系数持续低值(0.15), 摩擦面上无连续摩擦膜产生; 10m/s的制动速度下水气被解吸附, 摩擦面出现多层厚膜, 摩擦系数达到峰值(0.5), 此后, 随制动速度增加, 摩擦膜减薄, 材料磨损量呈下降趋势; 当制动速度增加到25m/s及以上, 摩擦面的温升导致氧化质量损失和线磨损增加, 摩擦系数也稍有衰减(0.3)。 

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).