Ultra-High Resistance to Electrochemical and High-Temperature Steam Corrosion of Mao/Cr Bilayer Coatings Fabricated on Zr Alloys

Abstract

In this work, MAO/Cr bilayer coatings were deposited on Zr alloys by combining micro-arc oxidation (MAO) and high-impulse-power magnetron sputtering (HiPIMS) techniques. The coating exhibited outstanding resistance to electrochemical and high-temperature steam corrosion. In simulated normal conditions, the charge transfer resistance of the MAO/Cr coating was 13 orders of magnitude higher than that of the Cr coating. Moreover, under simulated loss-of-coolant accident (LOCA) scenario, the MAO/Cr bilayer coating exhibited a weight gain roughly 15.5% lower than the Cr coating. These were mainly because MAO interlayer served as insulation diffusion barrier, inhibiting galvanic corrosion and element interdiffusion at the coating-substrate interface.

Keywords: MAO/Cr bilayer coating, Zr alloy, HiPIMS, Electrochemical corrosion, High-temperature steam oxidation