Wear and corrosion properties of in-situ TiC–TiB2 modified Ni-based composite coatings with different B/C ratios prepared by laser cladding

Abstract

The ever-evolving service conditions of high-end equipment continue to bring new challenges to the surface coating of the key components. Thus, modified nickel-based composite coatings with enhanced service performance must be further explored. The work aimed to improve the wear resistance and corrosion resistance of Ni-based coating by in-situ synthesis of TiC–TiB2 composite ceramic phase using TA0, B4C, and nickel (Ni)-coated graphite. First, coatings with different contents of B4C (from 3 wt% to 6 wt%) and Ni-coated graphite (from 0 wt% to 8 wt%) were prepared by laser cladding. The microstructure, phase composition, microhardness, wear properties, and electrochemical properties of the coatings were examined. The increase in the C/Ti ratio after adding Ni-coated graphite led to a decrease in the nucleation rate of the ceramic phase in the molten pool. Ultimately, the size of the ceramic phase gradually increased. The coatings with 3 wt% B4C and 8 wt% Ni-coated graphite showed the best wear resistance, with a 26.47 % reduction in wear volume compared with those of Ni-based alloy coatings. The variation in wear properties was due to the change in wear form caused by the increase in the size of the ceramic phase within the coating. The corrosion potential of the coating added with in-situ TiC–TiB2 increased by 39 % at best, and the corrosion current density was reduced by more than an order of magnitude. This finding was because the ceramic particles distributed throughout the grain boundaries increased the impedance of the coating and blocked the corrosion channels. This study provided theoretical guidance on the preparation of modified Ni-based coatings with excellent wear resistance and corrosion resistance.