High-Temperature Tribological Performance of Nano-Modified Multimodal Cr₃C₂-NiCr Coatings

This study investigated the high-temperature tribological performance of HVOF-sprayed nano-modified multimodal Cr₃C₂-NiCr coatings (NMC) compared to conventional Cr₃C₂-NiCr coatings (CC). High-temperature friction coefficients and wear rates of the coatings were evaluated various loads and temperatures. The microstructures, elemental/phase compositions of worn surfaces, and wear debris were characterized, analyzing the high-temperature wear mechanisms. Results indicated that the microstructure of NMC revealed a uniform and dense distribution of carbide particles across nano, submicron, and micron scales within the NiCr bonding phases, forming a unique multimodal structure. NMC exhibited significantly lower friction coefficients and wear rates than CC, with less severe surface damage. The superior wear resistance of NMC was attributed to the synergistic effects of the formation of dense, continuous, and well-adhered Cr₂O₃ oxide film protection, nano-reinforcement, and the multimodal structure’s ability to impede crack propagation.