Comparison of the corrosion resistance of Ni2Al3 coating with and without Ni-Re interlayer in dry and wet CO2 gas

Abstract Ni2Al3 and Ni2Al3/Ni-Re coatings deposited on Fe-Cr-Ni alloy were oxidized in dry and wet CO2 gas at 650 °C. Ni2Al3/Ni-Re coating shows higher oxidation resistance to both dry and wet CO2 gas than Ni2Al3 coating. It is attributed to the retarding effect of Ni-Re interlayer on interdiffusion between Ni2Al3 out-layer and substrate, which inhibits the subsequent inner oxidation during corrosion. θ-Al2O3 is found in α-Al2O3 scales of both coatings during wet CO2 corrosion. Water vapor accelerates the oxidation rate of both coatings in CO2 gas by promoting the formation of the fast growing θ-Al2O3 on the surface.