单摆冲击划痕法对封严涂层耐磨性的评价

涡轮机中封严涂层在减小转子与静子间隙,提高性能和效率上起着至关重要的作用,而抗冲击耐磨性决定封严涂层的服役寿命.单摆冲击划痕法模拟磨粒磨损且具有动态加载特性,可从力和能量两方面获得表层材料破坏过程的信息.通过单摆冲击划痕试验,研究了Al-Si-聚酯、Ni-石墨和Al-BN-水玻璃3种封严涂层的冲击划痕行为和比能耗曲线.结果表明:采用的拟合函数法可以较为方便、准确地计算出痕槽体积,随痕槽体积的增大,痕槽的实际最大深度与名义入侵深度的比值有逐渐增大的趋势,且痕槽形成的机制不同.刮削过程中3种封严涂层均有致密化倾向,痕槽形成过程中的塑性变形影响致密化.3种涂层中比能耗最大的为Al-Si-聚酯,耐磨性也最好;比能耗最小的为Ni-石墨,耐磨性最差;Al-BN-水玻璃的耐磨性介于二者之间.

Evaluation of Wear Resistance of Abradable Coatings by a Single-pass Pendulum Scratch Method

Abradable coatings can improve the efficiency and performance of turbo-machine by reducing the clearance between stators and rotors. The resistances of wear and erosion decides the service lifetime of the abradable coatings. By using single-pass pendulum scratching test, which is characterized for impact loading and simulates grain-abrasion, the information of wear loss in surface layer frictional forces and energy consumption could be obtained. In this paper, three abradable coatings were investigated by a single-pass pendulum scratching method and the scratching behavior and specific energy consumption curves of three coatings were achieved. The experimental results showed that suggestion of fitting function method could be used to calculate the groove volume easily and precisely. The ratio of practical maximum depth of groove to preset incursion depth increased with the increase of scratching size and the mechanisms of groove formation were different. There were densification behaviors for three coatings during rubbing and the plastic deformation influenced densification behaviors. The specific energy consumption of Al-Si-polymer was the largest one among three coatings, which means its best wear resistance. The Ni-graphite coating was the worst and Al-BN-sodium silicate was in the middle of wear resistance.