Erosion performance of HVOF-Sprayed Cr ₃C ₂-NiCr coatings

Cr ₃C ₂-NiCr coatings were deposited by high-velocity oxygen fuel (HVOF) spraying process under spray conditions of different flows of oxygen and propane gases, and spray distances. The orthogonal regression experimental design method was used for systematic investigation of the influence of spray parameters on the erosion performance of Cr ₃C ₂-NiCr coatings. Erosion tests were performed at different jet angles of abrasive particles. The erosion mechanism of Cr ₃C ₂-NiCr coatings was examined through the surface morphology and cross-sectional microstructure of the eroded coatings. The correlations of the carbide particle size and carbide content with the erosion rate were examined. It was found that the erosion occurred dominantly by spalling of splats from the lamellar interfaces. The spalling resulted from the propagation of cracks parallel to the interfaces between the lamellae exposed to the surface and underlying coating. The carbide particle size and content in the coating influenced significantly the erosion performance of Cr ₃C ₂-NiCr coatings.