指尖密封用炭-炭复合材料摩擦磨损性能

为确定指尖密封用炭-炭(炭纤维增强炭基体)复合材料的摩擦学性能,针对指尖密封的轻载使用条件,应用UMT-2摩擦磨损测试仪进行炭-炭复合材料摩擦磨损性能试验,测量摩擦系数与磨损率,并采用扫描电子显微镜(SEM)分析材料的摩擦磨损机理.结果表明,无纬布层垂直于摩擦平面时,材料的摩擦系数和磨损率较低.载荷增加,较高密度材料的磨损率增加缓慢,摩擦系数减小.与载荷相比,材料磨损率受频率的影响较小,且随频率升高摩擦磨损性能越好.磨损表面的SEM分析表明:低频、低载条件下材料发生磨粒磨损;频率的提高加快磨屑膜的成形,自润滑能力增强;载荷的增加虽使磨屑快速被挤压形成磨屑膜,但磨屑膜被不断挤出剥落,纤维裸露断裂产生严重磨损,这一点在材料密度较低时表现更为显著.选用较高密度的材料以及布置无纬布层垂直于摩擦平面可以有效缓解密封材料的磨损.

Friction and wear behaviors of carbon-carbon composites used in finger seal

The carbon-carbon (carbon fiber reinforced carbon matrix) composites were applied in the finger seal and the tribological behaviors were investigated using UMT-2 tribology tester under the light loads condition. The friction coefficient and the wear rate were measured. Friction and wear mechanisms were analyzed using SEM (scanning electron microscope) method. Results show that the friction coefficient and wear rate are lower when the non-woven cloth is perpendicular to sliding surface. For the higher density material, with increasing load the wear rate increases with small amplitude and the friction coefficient decreases. The frequency has less effect on the wear rate compared to the load on wear rate, and the tribological behaviors are better with increasing frequency. SEM analysis indicates as follows. First, abrasive wear occurs under low frequency and low load. Second, increasing the frequency quickens formation of the wear debris into film, and self-lubricating effect is strengthened. Last, although wear debris are quickly squeezed into film with increasing load, severe wear occurs due to fibers exposure and fracture with the film further squeezed out and peeled off. The effect of load on wear is notable when the material density is lower. Selecting higher density material and the material with non-woven cloth perpendicular to sliding surface can effectively mitigate wear.