Abstract: Six groups of Cr₃C₂-kNiCr coatings with NiCr content of 25%, 40%, 55%, 70%, 85%, and 100% are prepared by planetary ball mill and HVOF. The erosion rate of each coating at low, medium, and high impact angles is tested by erosion wear testing machine, and the erosion wear characteristics of the coating surface are observed. The elastic modulus, fracture toughness, and Vickers hardness of the six coatings are tested by nano-indentation tester, fracture toughness tester, and Vickers hardness tester. Meanwhile, the cross section morphology and porosity of the coatings are tested, and the microstructure, particle size, and composition of the powders are analyzed. The results show that the quality of each coating layer, interlayer, and interface is reasonable, and the porosity is lower than 0.46%. All powders have reasonable sphericity, uniform particle size and element distribution. With the increase of NiCr content, the microhardness and elastic modulus of each coating decrease stably, while the fracture toughness increases stably. The erosion wear behavior and characteristics of Cr₃C₂-kNiCr coatings change gradually from typical brittle material to typical plastic material with the increase of NiCr content. The erosion resistance of Cr₃C₂-kNiCr coating deteriorates gradually at low impact angle, and increases gradually at high impact angle. The mechanisms of erosion wear resistance under low and high impact angles are high hardness resistance to penetration of erosion particles and high toughness absorption of normal impact energy through plastic deformation, respectively. Therefore, the NiCr content of Cr₃C₂-kNiCr coating can be adjusted to meet the requirements of erosion resistance of the cermet coating at different impact angles.

Key words: HVOF, Cr₃C₂-kNiCr coating, erosion wear, impact angle, erosion rate