Study on Wear-resistant Self-lubricating Ni45/Cr₃C₂/MoS₂ Coatings Fabricated by Laser Cladding on 300M Steel

Two types of Ni45/Cr₃C₂/nickel-coated MoS₂ composite coatings with different Cr₃ C₂ contents were fabricated on the surface of 300M steel using laser cladding technology. The results indicate that with an increase in Cr₃ C₂ content, the intergranular Cr_xC_ystructures in the coatings transition from fine spherical and rod-like particles to elongated structures. Due to the flotation of hard phase particles, grain refinement, and the formation of intergranular secondary Cr_xC_y phases, the surface hardness of the coating with 6%Cr₃ C₂ reaches 511 HV0.5 and the average hardness is 520.43 HV0.5, while the coating with 9%Cr₃ C₂ exhibits a surface hardness of 633 HV0.5 and an average hardness of 599.42 HV0.5. Both composite coatings show a hardness increase of over 370 HV0.5 compared to the 300M steel substrate. The synergistic effect of sulfides such as MoS₂,Cr_xS_y, Ni S, partially dissolved Cr₃ C₂ particles, and secondary Cr_xC_y hard phase particles result in an average friction coefficient of 0.39736 for the coating with 6%Cr₃ C₂ and 0.34104 for the coating with 9%Cr₃C₂. At room temperature, the wear rate of the coating with 6%Cr₃ C₂ is 1.41388×10^-5mm³/（N·m）, slightly higher than 1.19249×10^-5mm³/（N·m） of the coating with 9%Cr₃C₂.The primary wear mechanisms for both coatings are identified as mild abrasive wear and oxidative wear.