航空发动机轴间密封用C/C复合材料的滑动磨擦磨损特性研究

【作者】 冯一雷；

【导师】 易茂中；

【作者基本信息】 中南大学 ， 材料学， 2003， 硕士

【摘要】 密封环是航空发动机主轴密封的关键零件。其工作条件和环境要求密封材料具有高强度、高抗氧化性、良好的导热性和低而稳定的摩擦系数与低的磨损等性能。本论文着重对不同工艺制备出的C／C复合材料和高强石墨材料在室温和高温下的滑动摩擦磨损特性进行了研究。 所有试样按制备工艺不同分为三组：CVD+树脂浸渍增密、纯CVD增密和纯树脂浸渍增密。采用CVD和三次树脂浸渍增密并经过最终石墨化处理后，1^#材料的密度为1.87g／cm³，石墨化度可达78％，其平行方向导热系数达75.9W／m·K。 C／C复合材料在室温下与钢的镀铬层对磨时，其摩擦磨损性能与制备工艺、石墨化度、密度、纤维取向等材料特性有着密切的关系。采用CVD+浸渍工艺制备并经过多次浸渍增密且石墨化后的1^#材料具有优良的摩擦磨损特性。其在150N载荷摩擦1h后，摩擦系数仅为0.12，体积磨损量仅为0.91×10^-4cm³。材料的石墨化程度越高，密度越大，其摩擦磨损性能也越好。一般情况下在载荷适中时，垂直试样的摩擦系数要大于平行试样，而体积磨损量却小于平行试样。总的来看，采用CVD+浸渍增密并具有以RL结构为主的1^#材料更适宜用作航空发动机主轴密封环。C／C复合材料在室温下的摩擦系数和磨损量都比高强石墨低，前者的摩擦系数在0.12～0.14范围内，而后者在0.25左右。C／C复合材料在室温下的摩擦磨损性能与时间、载荷、润滑状态等试验条件有着重要的联系。随时间的延长，材料的摩擦系数趋于稳定。载荷对摩擦膜有着重要影响，1^#材料在150N摩擦5h后，其摩擦系数仅为0.12。水润滑和油润滑状态下，材料的摩擦系数比干态下要低。但水润滑时材料的磨损量最大，4^#材料平行试样在150N水润滑摩擦5h后体积磨损量高达93.2×10^-4cm³。而油润滑时磨损量较小，干态下则最小。 温度对C／C复合材料的摩擦磨损性能有着重要影响。温度的升高引起摩擦表面粘着趋势增加，材料的摩擦系数和磨损量增大。对于1^#材料，在300℃时摩擦1h后摩擦表面形成的摩擦膜降低了粘着磨损的趋势，使得材料摩擦系数和磨损量较小。这说明，摩擦表面形成良好的摩擦膜是C／C复合材料在高温下摩擦磨损性能优异的一个重要因素。在高温下，不同载荷、转速和时间等试验条件对C／C复合材料的摩擦磨损性能也有着重要影响。随着载荷和转速的提高，C／C复合材料摩擦系数和磨损量增大。随着时间的延长，在“跑合”期结束后，C/C复合材料摩擦系数较低，磨损量趋于稳定。 C/C复合材料在室温下的摩擦磨损过程以磨粒磨损机理为主，在高温下的摩擦磨损过程为粘着磨损和氧化磨损机理，还伴随着有磨粒磨损。更多还原

【Abstract】 The seal ring is the critical part for the sealing of the main axis of aeroplane engine. According to the requirement of applying conditions, it must have high strength, excellent oxidation resistance and low coefficient of friction and wear ratio. Sliding friction and wear properties of C/C composites from different techniques and high strength graphite at normal temperature and high temperature were studied.All the samples were divided into three groups according to different techniques: CVD + resin impregnation densified, pure CVD densified and pure resin impregnation densified. After CVD and resin impregnation densified three times, the density of material 1# was 1.87g/cm3. Its degree of graphitization was 78%, and its thermal conductivity was 75.9W/mK.By sliding friction and wear of C/C composites and high strength graphite, it was found that the techniques, the degree of graphitization, the density and the fibre laying pattern were related to friction and wear properties of C/C composites. After CVD and resin impregnation densified three times and graphitizated, material 1# had a kind of good friction and wear properties. After friction at 150N in one hour, the coefficient of friction of material 1# was 0.12, and the volume loss was only 0.91 X 10-4cm3. When the degree of graphitization and the density were high, the materials had a kind of good friction and wear properties. Under the general situation, when the load was moderate, the coefficient of friction of perpendicular samples were higher than that of parallel ones, but the volume loss of perpendicular samples were lower than that of parallel ones. It indicates that material 1# had advantage over other materials when it was used as the seal ring of the main axis of aeroplane engine. The coefficient of friction and the volume loss of C/C composites were less than those of high strength graphite. The coefficient of friction of the former was from 0.12 to 0.14, and the high strength graphite’s was about 0.25. The time, the load, the lubrication formed were also related to friction and wear properties of C/C composites. When the time was extended, the coefficient of friction became stable. The load had some effect on the friction film. After friction at 150N in five hours, the coefficient of friction ofmaterial 1* was only 0.12. The coefficient of friction was less under water lubrication and oil lubrication. The volume loss was more under water lubrication. After friction at 150N in five hours under water lubrication, the loss of material 4" was 93.2 X 10-4cm3. But the loss was less under oil lubrication and was the least under normal condition.The temperature had some effect on the friction and wear properties of C/C composites. When the temperature increased and the surface had adhesion wear, the coefficient of friction and the loss was increased. After friction at 300C in one hour, the coefficient of friction and the wear of material 1# were less because the adhesion wear decreased by the friction film formed on surface. So the friction film formed on surface was an important factor on good friction and wear properties of C/C composites on high temperature. When the temperature was high, the load, the sliding speed and the time had important effects on the friction and wear properties of C/C composites. When the load and the sliding speed increased, the coefficient of friction and the wear increased. When the time was extended, the coefficient of friction of C/C composites decreased and the wear became stable.The abrasion is major, when the friction and wear on normal temperature of C/C composites. Adhesion wear and oxidation wear existed, accompanied with abrasion when the friction and wear on high temperature of C/C composites.更多还原