Laser cladded Ni625-xCr3C2 coatings: Microstructure, tribocorrosion and electrochemical properties

Ni625-xCr3C2 coatings were prepared on 45 steel by laser cladding to improve its tribocorrosion and electrochemical property. The microstructure, phases and hardness of obtained coatings were analyzed using a super-depth field microscope, X-ray diffraction, and microhardness tester, respectively, and the effects of Cr3C2 mass fraction on the tribocorrosion and electrochemical properties of Ni625-xCr3C2 coatings in 3.5 % NaCl solution were investigated. The results show that the Ni625-xCr3C2 coatings are mainly composed of gamma-Ni, Fe3C, Cr3C2, Mo2C, Cr7C3 and Cr23C6 phases, and their coating hardness increases with the Cr3C2 mass fraction, which are almost three times that of substrate. The coefficients of friction and wear rates of Ni625-5%Cr3C2, -10% Cr3C2 and - 15%Cr3C2 coatings are reduced compared with the Ni625 coating, and the wear mechanism is primary abrasive wear, accompanied with adhesive wear and pitting corrosion. Moreover, the polarization resistance of Ni625-5%Cr3C2, -10%Cr3C2 and - 15%Cr3C2 coatings are higher than that of Ni625 coating, showing that the corrosion resistance of Ni625-10%Cr3C2 coating was the best among the four kinds of coatings.