Effect of Chromium Carbide Addition on the Microstructures and Properties in Dual Carbide Phases Reinforced Ni-Based Composite Coatings by Plasma Cladding

Abstract

Cr3C2-modified NiCr–TiC composite coatings were prepared using the plasma spraying technique for different Cr3C2 contents on the microstructure and the properties of the Ni-based TiC cladding layer were investigated. The microstructures of the coatings were characterized using scanning electron microscopy, and the friction and wear performance of the coating was evaluated by the wear tests. The results revealed that the surfaces of the Cr3C2-modified NiCr–TiC composite coatings with varying Cr3C2 contents were dense and smooth. TiC was uniformly distributed throughout the entire coating, forming a gradient interface between the binder phase of the Ni-based alloy and the hard phase of TiC. At high temperatures, Cr3C2 decomposes, with some chromium diffusing and forming complex carbides around TiC, some chromium solubilizes with Fe, Ni, and other elements. An increase in chromium carbide content leads to an upward trend in hardness. The measured hardness of the coatings ranged from 600 to 850 HV3 and tended to increase with increasing Cr3C2 content. When the mass fraction of Cr3C2 reached 30%, the hardness increased to 850 HV3, and the cracks and defects were observed in the coating, resulting in a wear resistance decline.