High Temperature Corrosion Behavior of Cold Spray Ni-20Cr Coating on Boiler Steel in Molten Salt Environment at 900 °C

In this investigation, Ni-20Cr alloy powder was deposited on SA 516 boiler steel by cold spraying. The oxidation kinetics of both coated and uncoated samples, evaluated in molten salt, followed a parabolic rate. The rate constant of the Ni-20Cr coated steel was much lower than that of the bare boiler steel. X-ray diffraction, SEM-EDX, and X-ray mapping were used to analyze the oxidation products of the coated and uncoated boiler steel. The uncoated steel exhibited intense spalling and peeling of its oxide scale, which may be due to the formation of Fe₂O₃ oxides. The Ni-20Cr coating reduced the weight gain of the steel by more than 87% possibly due to the formation of nickel and chromium oxides.