Corrosion Resistance of Boride Cladding by Plasma Cladding

The boride cladding was prepared by plasma cladding technique on the surface of 316L stainless steel with Mo-Fe-B-Cr flux-cored wire. The microstructure, composition, phase and micro-hardness of the boride cladding were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and micro-hardness meter. The corrosion resistance of the cladding was studied by electrochemical test and neutral salt spray test. The results show that the boride cladding was mainly composed of Mo₂FeB₂, (Mo, Fe, Cr) ₃B₂, α-Fe and Fe₂₃(C,B)₆, and the micro-hardness of the cladding was about 3.9 times that of the stainless steel substrate. The corrosion resistance of the boride cladding in neutral environment was slightly lower than that of 316L stainless steel; and the corrosion resistance of the boride cladding in acidic environment was better than that of 316L stainless steel. In the process of neutral salt spray corrosion, a good dense passivation film formed on the surface of boride cladding, giving a good corrosion resistance of the cladding. So the boride cladding had both high hardness and good corrosion resistance.