Preparation and Corrosion Resistance of an Al2O3/Ni Coating on 316 Stainless Steel in Molten 52MgCl2-48NaCl Chloride Salt

In this paper, in order to improve the corrosion resistance of 316 stainless steel (316 SS) in molten chloride salt, an in situ grown Al 2 O 3 diffusion barrier is prepared through, first, electrodepositing an inner Ni-Al/NiO composite transition layer and an outer Ni layer through double-pulse composite electroplating technique, followed by annealing at 800°C for 12 h under Ar. The obtained Al 2 O 3 /Ni composite coating is dense and shows good adherence to the substrate. Then the corrosion resistance of Al 2 O 3 /Ni composite coating in molten 52MgCl 2 -48NaCl (wt%) is measured through electrochemical technique and immersion tests and the corrosion mechanism is also discussed. The results show that the 316 SS is effectively protected by the Al 2 O 3 /Ni composite coating from the corrosion of molten chloride salt.