The friction and wear behaviour of several kinds of middle temperature abradable seal coatings used in aircraft turbine engine was investigated. Their abradability was evaluated by sliding worn volume. The mechanisms of the sliding wear of the coatings are abrasive wear, adhesive wear and oxidation wear, but the weight of the adhesive wear and abrasive wear is different in different coatings and under different test loads. The results show that the abradability decreases with the increase of the hardness for a given kind of coating. Even if the hardness is close, the abradability is very different in different kinds of coatings. So, only by the hardness can the level of abradability not be not judged and the coating not be chosen and designed. The abradability of M313 type of coating is the best, M310 is close to M601 and M307 with low hardness is fairly good, but M307 with high hardness is the worst. q1999 Published by Elsevier Science S.A. All rights reserved.

The abradable seal coating for an aircraft turbine engine is mostly composed of metal phase, self-lubricating non-metal phase and many pores. The erosion wear resistance is one of the most important properties of the coating. The erosion wear behaviour and mechanism of several kinds of middle temperature seal coatings were investigated by a CMS-100 self-made vacuum sand erosion machine. The results show that the relationship between the erosion mass loss and the erosion time is linear, the coatings hold a maximum erosion rate at 60◦ impact angle, and the relation between the erosion rate and the impact speed is an exponential function. The speed exponent increases with the increase of the impact angle. At 90◦ impact, the abrasive particles impinging on the coating surface produce indentations and extruded lips, and then the lips are work-hardened and fall off; and flattened metal phase grains are impacted repeatedly, loosed and debonded. At 30◦ impact, the micro-cutting, plowing and tunneling via pores and non-metal phase are involved. The model of the erosion mechanism is advanced on the basis of the above-mentioned erosion wear behaviour.

采用MG-2000型摩擦磨损试验机对比考察了C/C复合材料及航空发动机主轴密封环拟用材料高强石墨的高温摩擦磨损行为，采用显微激光拉曼光谱仪及扫描电子显微镜分析了C/C复合材料磨损表面组成及形貌。结果表明：具有粗糙层和光滑层复合结构的C/C复合材料的高温摩擦磨损性能明显优于高强石墨材料，适合用作航空发动机主轴密封环材料；C/C复合材料的高温摩擦磨损性能取决于磨粒磨损、粘着磨损及氧化磨损的共同作用。

在MM-2000环-块摩擦试验机上测试了C/C复合材料的摩擦磨损行为。通过对试样在不同时间、不同载荷、不同润滑状态下的摩擦磨损试验得出：随时间的延长，C/C复合材料的摩擦系数趋于稳定。在摩擦试验后期，材料摩擦系数一直保持在0.12。载荷对磨屑膜有着重要影响，材料平行试样和垂直试样在150N摩擦5h后，其摩擦系数仅为0.12。水润滑和油润滑状态下，材料的摩擦系数降低，仅为0.05～0.08。水润滑时材料磨损量增加，油润滑时磨损量较小，干态时磨损量最小。

对B（波音）757和B767飞机用C/C复合材料刹车盘试样的氧化行为进行了研究。在实验温度范围内，B757的刹车盘材料氧化损失率与温度有三段式关系，而B767的有二段式关系，所对应的氧化敏感温度分别约为600和700℃；在氧化敏感温度以上和以下氧化动力学曲线分别为直线型和指数型；B757刹车材料为2层薄炭毡中间夹1层纤维布组成的单元叠层构成，纤维布的纤维方向互成90ο；B767刹车材料为无捻长纤维按一定角度旋转铺层，并在层面上辅加适量随机取向的短纤维束。材料氧化时首先在纤维与基体交界处氧化，基体炭氧化较深，纤维炭氧化成针尖状；但B757刹车材料的炭毡纤维氧化程度较深而成管状。