Effect of impingement angle on erosion wear behavior of HVOF Cr₃C₂-NiCr coating

High-velocity oxygen-fuel (HVOF) technology was adopted to prepare a Cr₃C₂-NiCr cermet composite coating on the surface of 1Cr18Ni9Ti stainless steel. The microstructure, phase composition and erosion of the coating and stainless steel, the relationship between impingement angle and erosion resistance were studied. The results show that the coating structure is compact and uniform, mainly composed of Cr₃C₂ and a small amount of Cr₇C₃, Cr₂₃C₆ and (Ni, Cr) solid solution phases. The erosion resistance of the Cr₃C₂ -NiCr coating decreases with the increase of the impingement angle. At low impingement angles, the damage of the coating is mainly micro-cutting, and the weight loss is low, showing excellent erosion resistance. As the impingement angle increases, the erosion sand particles have a vertical impact on the coating, cracks between the binder phase and the hard phase cause the adhesion phase to fall off, thus the hard phase loses the support of the binder phase and is exposed, peeling off under the continuous attack of erosive sand, forming many small erosion pits. With the increase of the number of hard phases peeling off, small erosion pits gradually develop into large erosion pits, with greater weight loss and poor erosion resistance.