Numerical Prediction of the Influence of Rub-Induced Thermal Stress on the Abradability of CuAl-Polyester Sealing Coating.

Thermal stress is an important factor affecting the abradability of seal coatings. In this paper, the relationship between rub-induced thermal stress and abradability of CuAl seal coating was studied based on thermal–mechanical coupling finite element method using ABAQUS software and a high-temperature and high-speed abradability test rig. The thermal stress simulation results show that the contact friction coefficient and incursion conditions between blade and coating have an important influence on the rub-induced thermal stress of the coating. The peak stress of the coating surface and the coating–casing interface increased with the increase in the friction coefficient when it was in a range of 0.01-0.3, which increased by 192 and 233%, respectively. The peak stress of the coating surface and the coating–casing interface was the minimum when the blade incursion depth and speed were 100 μm and 500 μm/s, which were 406.23 and 313.71 MPa, respectively. The abradability of CuAl seal coating increased with the decrease of coating feed speed when it was in a range of 10-100 μm/s, and the incursion depth ratio decreased from 12.9 to 8.82%. Combined with the high-temperature hardness and residual thermal stress test results, the release of thermal stress from the porous structure and the reduction of hardness during the scraping process are concluded to be the main reasons for maintaining good abradability of the coating. This work has an important reference value for further study of the influence of thermal stress on abradability. [ABSTRACT FROM AUTHOR]