石墨化度对炭/炭复合材料在不同制动速度下的摩擦磨损性能的影响

将炭布叠层的炭纤维预制件通过化学气相沉积增密后分别在2 000、2 150、2 300 ℃进行高温热处理得到3 种不同石墨化度的炭/炭复合材料, 采用MM-1000 摩擦试验机对这3 种炭/炭复合材料进行不同速度下的摩擦磨损性能试验, 并对磨损表面及磨屑进行SEM 观察, 结果表明:低速时材料的摩擦系数均很小;刹车速度为10 m/s 时, 石墨化度对材料的摩擦系数影响显著, 石墨化度越高, 材料的摩擦系数越大, 石墨化度低的样件A 摩擦表面形成薄且光滑的磨屑层, 而石墨化度高的样件C 摩擦表面形成厚的、粗糙的磨屑层;刹车速度大于20 m/s 时, 石墨化度对材料摩擦系数的影响变小, 3 种材料摩擦表面均形成较为平滑的磨屑层。石墨化度的高低显著影响材料高速时的磨损, 石墨化度升高到一定值时能显著降低材料高速时的磨损, 继续升高石墨化度, 磨损变化不大,高速时石墨化度低的样件A 氧化严重。综合考虑摩擦磨损性能, 该粗糙层结构的炭/炭复合材料石墨化度控制在45 %为宜。

Effect of Graphitization Degree on Friction and Wear Properties of Carbon-Carbon Composites at Different Braking Speed

Carbon fibre preform is densified by chemical vapor deposition and treated at 2 000, 2 150, 2 300 ℃ respectively,obtaining 3 C/C composites with different graphitizing degrees.Their friction and wear properties are tested by a MM -1000 friction rig at different speeds and their worn surfaces and debris are observed by a scanning electron microscope.The results have shown that their friction wefficients are very small at low speed.At a braking speed of 10 m/s the effect of graphitization degree on the material' s friction coefficients is notable.The higher the graphitization degree, the higher the material' s friction coefficients.Sample A, with a lower graphitization degree, has a thin and glossy debris layer on its surface, and Sample C,with a higher graphitization degree, has a thick and rough debris layer.When the braking speed is above 20 m/s, their graphitization degree has a small effect on their friction coefficients, and they all have smoother debris layers on their friction surfaces.The graphitization degree has obvious effect on the material' s wear at high speed.When it increases to a certain degree, the material' s wear will be reduced, and when it continues to increase, the material' s wear varies little.At high speeds,Sample A with a lower graphitization degree is badly oxidized.To consider comprehensively their friction and wear properties,their graphitization degrees should be 45 %.