Oxidation behavior of Ni-Mo-Si alloy coatings fabricated on carbon steel by laser cladding

In this study, Ni-Mo-Si alloy coatings with different compositions were prepared on the surface of AISI 1045 steel by laser cladding. The microstructure and phase composition of different alloy coatings were studied by SEM, EDS and XRD. The oxidation resistance of the alloy coating was investigated in the static air environment at 800 degrees C. The results showed that: All the gamma-Ni-ss/Mo2Ni3Si alloy coatings exhibited similar oxidation behavior and the oxidation kinetics curves followed a comprehensive linear-parabolic law. The total mass gain of N60, N55 and N50 alloy coating were 3.28 mg/cm(2), 2.98 mg/cm(2), 2.69 mg/cm(2), respectively. The oxide layers covered on the alloys were uniform and dense, which were mainly composed of NiO, Fe2SiO4, SiO2 and MoO3. With the increasing Si content in the designed alloy, a continuous SiO2 film formed inside the oxide layer, which could effectively hinder the diffusion of oxygen and Ni2+ in the oxide layer. Among the designed alloy coatings, N50 coating exhibited the lowest oxidation rate and the best oxidation resistance.