Study on Abradability and Room Temperature Erosion of an AlSi–hexagonal Boron Nitride Seal Coating

Abradable seal coatings are widely employed in the gas turbine of aero-engine, which not only strength enough to resist the impact of external particles and airflow, but also excellent wear resistance. In the current study, we concentrate on APS sprayed AlSi–hBN abradable coating that can be used in turbo engines both for seals and clearance control. A high temperature and speed test rig has been developed by BGRIMM for testing the AlSi–hBN abradable seal coating and Ti-6Al-4V dummy blade. Impact velocities between 250 and 400m·s^-1 and incursion rates between 5.0 and 500 μm·s^-1 have been applied. In addition，the erosion behavior at room temperature (RT) of the AlSi–hBN coating was investigated. The erodent material was 50 μm alumina and the impact angles were 20° and 90°. The erosion performance of the different conditions in this study was ranked based on the coating depth and weight loss after wear testing. The coating microstructures and phase compositions were evaluated via SEM and XRD. The erosion mechanisms of the coating were compared by analyzing the cross-sectional and top surface microstructures of the as-sprayed and eroded coatings.