Corrosion Resistance to Molten Zinc of a Novel Cermet Coating Deposited by Activated Combustion High-Velocity Air Fuel (AC-HVAF)

Molten zinc is very aggressive to austenitic stainless steels. In this study, a novel cermet coating consisting of FeB-12 wt.%Al 0.25 FeNiCoCr was deposited on the surface of 316L stainless steel to protect it from liquid zinc corrosion using activated combustion high-velocity air fuel (AC-HVAF). The microstructure and phase composition of the powders and coating were determined by scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) analysis. The thermal expansion coefficient, microhardness, thermal shock resistance, abrasive wear resistance, and corrosion resistance to molten zinc of the coating were investigated. The results showed that the first macrocrack appeared on the surface of the coating after 32 thermal shock cycles. Compared with the 316L stainless steel substrate, the abrasive wear resistance of the coating was twice as high. Also, the average corrosion rate of the FeB-12 wt.%Al 0.25 FeNiCoCr coating in molten zinc at 450 °C was 16.17 μ m/day, much lower than the value of 115.44 μ m/day for 316L stainless steel in molten zinc at 460 °C.