Damage research of supersonic plasma sprayed Al2O3/PF composite coatings on resin matrix surfaces under thermally coupled operating conditions

Abstract

Al₂O₃/PF composite coatings are commonly used to improve the surface properties of resin materials in complex environments with coupled thermal and structural fields. In order to explore the factors of composite coating performance degradation, the coupling model of temperature field and structural field was established, and the stress change of the composite coating in the coupling field was analyzed. According to the simulation results, it is known that the middle part of the coating and the overlapping area of the heat-affected region are most prone to crack extension and delamination. In order to verify the simulation conclusions, the damage behavior of Al₂O₃/PF composite coatings in the extreme environment of multi-physical fields and the spatial evolution law were summarized and the composite coatings were experimentally analyzed. With the increase of the number of thermal coupling, the microstructure of the composite coating shows the formation and expansion of porous structure and cracks, which leads to a decrease in the protective performance of the coating. With the accumulation of the number of coupling times, the coating is damaged layer by layer from the cracks, and the damage is mainly concentrated in the already cracked parts, while the uncracked area can still maintain a certain degree of integrity and continue to provide thermal protection for the substrate. The results of the nanoindentation tests further confirm that layer-by-layer damage of the coating occurs from surface to surface under thermal coupling. The results emphasize the joint influence of temperature and mechanical loading on the material properties and provide a theoretical reference for the study of thermal coupling problems in similar materials.