炭/炭复合材料飞机刹车盘表面加工质量对其磨合性能的影响

THE RELATIONSHIP BETWEEN SURFACE QUALITY AND THE RUNNING-IN CHARACTER OF CARBON-CARBON COMPOSITE (CCC) AIRCRAFT BRAKES

在mm 10 0 0试验机上对炭 /炭复合材料 (CCC)飞机刹车盘 3组表面粗糙度不同的试样进行刹车模拟试验。在摩擦表面相对作切向运动时 ,摩擦表面微凸体发生弹 -塑性变形、发生磨损进入磨合状态。采用Talysurf 4仪测定了CCC刹车盘磨合前后的表面形貌及其粗糙度 ,用SEM对磨损表面和磨粒形貌进行了研究。当刹车盘表面波度较小而表面微观粗糙度在Ra =12 .5 μm时 ,有利于在摩擦面上形成摩擦膜 ,使刹车副很快进入磨合状态。

The surface quality effect on the friction and wear properties and the running-in characteristics of the carbon-carbon composite (CCC) aircraft-braking disks was investigated. Because the peaks of asperities on the mating surfaces mutually penetrate as the surfaces move tangentially relative to each other, plastic-elastic deformation occurs in the surface layer. The surface friction film depends on the depth of the deformed layer and the quantity of the wear particles. The latter depends on the surface roughness of the CCC disks. The surface morphology, roughness, and profiles of the machined and worn surfaces are measured with a Talysurf-4, and studied using SEM. Running-in deforms the machined surface roughness Ra (arithmetic mean deviation of the profile, which can be directly read from the profilometer or surface analyzer) to a deformed Ra. Running-in is optimal when the machined surface roughness is slightly greater than deformed surface roughness after running-in, and the optimal value of the machined surface roughness in this study is 12.5 mum. The properties of the surface layer of a material depend significantly on the cutting process. A correct machining method should produce a high precision surface with little undulation but a large roughness may shorten the running-m time and decrease the number of running-in braking cycles.