Study on Melting-Precipitation Evolution of WC in Ni/WC-12Co Coating during Laser Cladding and Tribological Properties

Ni/WC-12Co cladding coating was prepared by laser cladding with the agglomerated WC as the reinforced phase. Microstructure analysis showed that main phases of the Ni/WC-12Co cladding coating were gamma-Ni, (gamma-Ni, WC)(Eutectic), WC, and W2C. At higher heat input state (2 mm/s), the content and particle size of WC reinforcing phase increased, indicating that the WC appeared melting precipitation growth phenomenon. At lower heat input state (6 mm/s), the particle size of the WC reinforcing phase decreased, and its distribution became uniform with the decrease of the cooling rate. Furthermore, the tribological performance of micro-nano WC-reinforced Ni-based cladding coating (6 mm/s) exhibited excellent wear resistance under the conditions of dry sliding and 3.5 wt.% NaCl. In addition, under erosion conditions, the wear resistance of Ni-based cladding coating (6 mm/s) was nearly a hundred times lower than that of the large spherical WC-reinforced Ni-based cladding coating. Therefore, by controlling the melting and precipitation of WC, a micro-nano WC-reinforced Ni-based coating with excellent mechanical properties was prepared by laser cladding, which provided a new idea for the research and development of micro-nano WC-reinforced Ni-based cladding coating.