The Damage Evolution of a Cr2O3-TiO2 Coating Subjected to Cyclic Impact and Corrosive Environments and the Influence of a Nickel Intermediate Layer

Cyclic impacts in corrosive environments significantly affect the service life of ceramic coatings, greatly increasing their susceptibility to cracking and delamination. This study investigated the damage evolution behavior of Cr2O3-TiO2 (CT) coatings under cyclic stress in a corrosive medium, and analyzed the effects of the nickel layer on coating stress, corrosion current, and crack propagation. The variations in corrosion potential and current were analyzed, and the formation patterns of interfacial corrosion cracks were observed. Pre-cracks were introduced on the ceramic coating surface using a Micro-Nano mechanical testing system, and cyclic impacts were applied to the samples in 5% diluted hydrochloric acid using SiC balls to induce damage evolution. The results indicate that the presence of the nickel interlayer reduced the corrosion current density from 9.197 × 10−6 A/cm2 to 8.088 × 10−6 A/cm2 and significantly decreased the stress between the coating and the substrate. The surface cracks gradually extended toward the interface under the coupling effect of corrosion and SiC ball impact. When cracks reached the interface, they provided channels for corrosive media, leading to stress corrosion cracking at the interface. The Ni intermediate layer suppressed the formation of interface cracks and greatly enhanced the impact damage resistance of the CT coating–substrate system in corrosive media.