Stress Field Evolution of Antifriction Wear-Resistant Sealing Coatings on GH4169 Superalloy Substrate under Thermal Shock

Finger sealing has potential application prospects in aerospace engines and gas turbines. An antifriction wear-resistant sealing coating (AWSC) is used on the rotor seal track to improve the service life of a finger seal. Thermal shock resistance is an important indicator of the coating properties. In this research, finite-element numerical simulation of thermal shock to an AWSC system was carried out, and the mechanism of thermal shock stress fatigue failure of the AWSC was analyzed. Variations of AWSC composition, AWSC thickness, and bonding coating thickness on thermal shock stress of the coatings were evaluated. The results show that significant radial tensile stress is generated at the AWSC surface in the initial stage of thermal shock, which may lead to vertical cracks in the surface. During the thermal shock process, the AWSC surface generates significant compressive stress. Significant axial and shear tensile stresses are generated at the AWSC/bonding coating interface, which readily cause cracking and interface failure. Radial tensile stress of the AWSC decreased in the initial stage of thermal shock with an increase in AgMo content. Greater thicknesses of the AWSC and bonding coating can reduce the main stress component on the AWSC surface and enhance its thermal shock resistance.