Mechanism of Zr in in situ-synthesized particle reinforced composite coatings by laser cladding

By adding mixture of ZrO 2 and carbon, a Zr-enhanced composite coating was produced onto an AISI 1045 substrate by laser cladding. The microstructure and phase formation, microhardness and wear resistance of the composite coating were studied. The experimental results indicate that the composite coating with metallurgical bonding to substrate consists of γ-Ni, massive ceramic particles of ZrC, NiZr 2 , Ni 7 Zr 2 , (Fe, Ni) 23 C 6 and Fe 3 C. The in situ-synthesized ZrC particles are uniformly dispersed in composite coating, which refines the microstructure of composite coating. With different ZrO 2 and carbon additions, the properties are improved differently. Finally, the fine in situ ZrC particles improve the microhardness of composite coating to HV 0.2 650, which is nearly 2.7 times that of Ni25 coating. Also, the composite coating has an advantage in wear resistance; it offers better wear resistance when more mixture of ZrO 2 and carbon was added in nickel alloys.