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.