Behaviour and Mechanisms of Alkali Metal Sulphate-Induced Cyclic Hot Corrosion in Relation to Gradients and Preoxidised MCrAlY-Type Coatings

In this study, two modified MCrAlY-type coatings were prepared by the same arc ion plating process. ‘Gradient annealing’ and ‘gradient annealing plus preoxidation’ adopted as post-treatments for coatings. A two-layer scale of a mixed oxide layer pure alumina with next to substrate was formed on latter coating. cyclic hot corrosion test carried out them conventional coating reference. The kinetics evolution microstructure showed have greater resistance at 900 °C. preformed inner preoxidation retarded occurrence internal oxidation–sulphidation some extent. Additionally, sulphidation–oxidation model is elucidated extended.