Characteristic, corrosion and high-temperature steam oxidation behavior of FeCrAl-coated Zr alloy by magnetron sputtering: Synergistic effect of deposition temperature and substrate bias

Six FeCrAl coatings were prepared on Zr-4 alloys by altering deposition temperature and substrate bias using magnetron sputtering. The synergistic effects of these two deposition parameters on surface characteristic, microstructure, mechanical properties and corrosion behavior in autoclave (360 degrees C and 18.6 MPa) of FeCrAl coatings were evaluated systematically. Furthermore, high-temperature steam oxidation behavior of the FeCrAl coating was also investigated. Results indicated that the FeCrAl coating deposited at 300 degrees C and - 120 V exhibited the best protectiveness by forming a multilayer oxide scale consisting of outer FeCr2O4 and Fe3O4 spinel particles and inner (Fe,Cr)2O3 together with Al2O3 layer. During 800 degrees C steam oxidation, a continuous three-layered oxide scale consisting of Fe2O3, Cr2O3 and Al2O3 from outside to inside achieved effective protection for Zr substrate. The voids inside the oxidized FeCrAl coating experienced self-healing. However, after exposure to 1000 degrees C steam, the FeCrAl coating lost protectiveness because of the rapid Fe-Zr interdiffusion followed by its eutectic reaction at the coating/substrate interface. The related corrosion and oxidation as well as failure mechanisms were finally discussed.