Effect of w(Ti+B₄C+C)/w(Ni60A) on Structure and Performance ofNickel-Based Composite Coating by Plasma Cladding

With Ni60A alloy, Ti, graphite (C), and B₄C powders as raw materials and adjusting w(Ti+B₄C+C)/w(Ni60A) (w is mass fraction/%) to 0:100, 10:90, 20:80 and 30:70, nickel-based composite coatings were synthesized by reactive plasma cladding on surface of 304 stainless steel. The effects of w(Ti+B₄C+C)/w(Ni60A) on the formability, microstructure, hardness and wear resistance of the coating were studied. The results show that the nickel-based composite coatings with Ti+B₄C+C were metallurgically bonded to the substrate, and were mainly composed of (Ni, Fe), CrB, TiC and Cr₃Si. Increasing w(Ti+B₄C+C)/w(Ni60A) improved the precipitation of strengthening phases and decreased the formability. CrB dispersed in the middle and lower part of the coating in gray-black slender strip forms, while in the upper part in small block or rod forms. TiC dispersed in the coating in fine particle forms. When w(Ti+B₄C+C)/w(Ni60A) was 20:80, the comprehensive performance of the coating was relatively good; the average microhardness was the highest (948 HV) and the cross-sectional area of the wear scar was about 1/5 that of the pure Ni60A alloy coating. Adhesive wear and oxidative wear mainly occurred in nickel-based composite coatings.