Influence of laser power on the microstructure and properties of in-situ NbC/WCoB–TiC coating by laser cladding

Abstract

In this research, in-situ synthesized NbC in the WCoB–TiC composite coating was fabricated via laser cladding with variable laser power. The microstructure, elemental distribution, microhardness, wear resistance, and fracture toughness were analyzed. The results showed the excellent metallurgical bonding between the coating and the substrate was formed. With the increase of laser power, the grain size of the coating increased, and density decreased. Elemental distribution results showed that niobium reinforced phases were distributed uniformly in the TiC. Following the increase of laser power, the dilution rate increased, while the porosity and crack showed opposite results. The microhardness was decreased following the increase of laser power, and the highest microhardness of coating reached 2034.4 HV0.5 when the laser power was 1500 W. When the laser power was 2500 W, the COF, wear mass loss, and KIC were 0.49, 4.3 mg, and 8.31 MPa⋅m1/2, respectively. The wear form of the composite coating was mainly adhesive wear and abrasive wear. In summary, the microhardness, wear resistance, and fracture toughness can be significantly improved by adjusting laser power.