In-situ synthesis of WC/TaC reinforced nickel-based composite alloy coating by laser cladding

Abstract:

An in-situ synthesized WC/TaC reinforced nickel-based composite coatings have been fabricated on AISI 1045 mild carbon steel substrate by laser cladding of powder mixture of Ni60/WC with Ta2O5 and graphite. The microstructure and hardness distribution of WC/TaC/Ni60 composite coating are investigated utilizing scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. It is shown that the microstructure of coating has a metallurgical bonding with substrate and is mainly composed of γ-Ni dendrites, W₂C, M₇C₃ carbides, and dispersed TaC particles. The hardness of WC/TaC/Ni60 composite coating has been enhanced to a value similar to that of HV965, which is 1.3 times higher than Ni60 coating. Measurement results demonstrated that these improvements are attributed to the presence of in-situ synthesized TaC particles, microstructure change and phase variations.

Key words:Laser cladding; Nickel-based alloy; Tantalum(Ta); Tantalum carbide(TaC); Tungsten carbide (WC)