Evaluation of an AlSi-polyester abradable seal coating performance using high-temperature and high-velocity abrasion tests

The application of abradable seal coating is an effective method to improve the efficiency of turbine engines. The AlSi-polyester is a typical one, which has been widely used in mediate and low pressure compressors. To evaluate abradable performance and investigate wear mechanisms of these seal coatings, a high-temperature and high-velocity tester was constructed, with 520m/s maximum blade tip speed and 5-2000m/s incursion speed and 1200? maximum heating temperature. Abrasion tests with blade tip velocities between 150 and 300m/s and incursion rates between 13 and 500m/s have been conducted under 350? to investigate the wear behavior between Ti6Al4V blade and an AlSi-polyester coating sample. The coating abradability was evaluated after abrasion tests through analyzing the mass losses, wear morphology, and interaction force of the coating and blade. It is found that the AlSi-polyester seal coating used in our research has good abradability to protect the Ti6Al4V blade tip, and abrasion wear is its predominant wear mechanism with furrow surface morphology. Incursion per pass has significant impact on the variation tendency of interaction force, with tests at low incursion per pass showing stable tendency and lower force, whereas tests at high incursion per pass showing gradual rise before relatively stable trend and higher force. This work provides a new basic data for the preliminary study of the interaction between blade tips and abradable coatings in aero-engine applications.