Study on process and performance of thermal protective coating on polyimide resin matrix composite

Abstract In order to expand the application of polyimide resin matrix composites in the hot stage components of aeroengine, YSZ-based thermal protective composite coating was prepared on the surface of polyimide-based composites by detonation gun spraying. Sandblasting, sandpaper polishing and laser ablation were used to improve the surface roughness of the composites matrix. Bond bottom layer (Al, Cu, Zn), NiCoCrAl intermediate transition layer and YSZ top layer were matching with different thickness. The cross-section structure of the composite coating observed by SEM shows that the composite coatings of 0.1 mm Al bottom layer, 0.1 mm NiCoCrAl transition layer and 0.3 mm YSZ top layer are the best thickness matching for thermal protection of polyimide-based composite materials. There is no thermal damage to the surface and interior of the substrate during the preparation of the coating. The cross-section structure of the coating is uniform, and the interface between the layers is closely bonded and no micro-damage, Cracks and holes appear. After sandblasting, the bonding strength of the coating is 16.5 MPa by lattice laser texture treatment. The structure and thermal insulation properties of the composite coating are the best at 800 °C. The thermal conductivity is 1.46 W/(m·K), the specific heat capacity is 0.58 J/(g·K), and the thermal expansion coefficient is 7.89 × 10-6/K.