68 / 2021-06-30 12:08:44

Effect of Y2O3 on Microstructure and Wear Resistance of Ti6Al4V/NiCr-Cr3C2/Y2O3 Composite Coating by Laser Cladding

Laser Cladding, Y2O3, Ti6Al4V, Wear resistance, Microstructure

In order to improve the wear resistance of Ti6Al4V, the coaxial powder feeding laser cladding technology is used to prepare Ti6Al4V/NiCr-Cr₃C₂/Y₂O₃ functional coating on the surface of Ti6Al4V substrate, and the influence adding 2wt% Y₂O₃ on the composite coating of the forming quality, microstructure, hardness and wear resistance is systematically analyzed through NDT, SEM, XRD, EDS, EPMA, TEM, etc. This research shows that Y₂O₃ can significantly improve the forming quality of composite coatings. When adding Y₂O₃ to the composite coating, the penetrating cracks on the surface disappeared, and no small cracks were found. And the porosity of the composite coating was reduced from 3.29% to 1.5%, and the volume and number of pores were significantly reduced. The dilution rate and coating thickness were also both has increased. The addition of Y₂O₃ does not change the phase composition of the composite coating, which is still mainly composed of the matrix phase CrTi₄ and the reinforcing phase TiC_x, but the fishbone-like titanium carbide in the coating increases. At the same time, many needle-like and petal-like titanium carbide appears in the coating because of the grain refinement mechanism of Y₂O₃. The hardness of the coating dropped from 394.2HV_0.5 to 379.6 HV_0.5, and the wear rate rose from 5.37 to 5.92（×10^-5mm³/(N·S））. The addition of a small amount of rare earth Y₂O₃ effectively improves the forming quality of the composite coating, but has little effect on the wear resistance of the coating.