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 Al2O3 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 degrees C for 12 h under Ar. The obtained Al2O3/Ni composite coating is dense and shows good adherence to the substrate. Then the corrosion resistance of Al2O3/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 Al2O3/Ni composite coating from the corrosion of molten chloride salt.