MoB–CoCr as alternatives to WC–12Co for stainless steel protective coating and its corrosion behavior in molten zinc

Erosion of sink rolls by molten zinc is one of the most prominent and persistent problems occurring in hot-dip galvanizing industry. MoB–CoCr as an alternative to WC–12Co for stainless steel protective coating resistance to molten zinc was deposited by high velocity oxygen fuel (HVOF). Microstructure and mechanical characterization of the coatings were carried out by SEM, XRD and micro-hardness test. Resistance to thermal shock and molten zinc corrosion of the coatings were also conducted. Results showed that MoB–CoCr coating exhibited a better resistance property to thermal shock than that of WC–12Co. At the same time, the corrosion test showed that lifetime of samples with MoB–CoCr coatings in molten zinc appeared to be longer than that of WC coating. The corrosion resistance of MoB–CoCr coating may be ascribed to non-wettability of MoB–CoCr in molten zinc, which can delay the molten zinc penetration into substrates along the micro-cracks of the coating.