Preparation and Hot Corrosion Behavior of a NiCrAlY + AlNiY Composite Coating

In this study, a NiCrAlY + AlNiY composite coating was prepared by arc ion plating technique and subsequent annealing treatment. Cyclic hot corrosion tests of the composite coating and a reference NiCrAlY coating coated with mixed salts of Na2SO4 + K2SO4 and Na2SO4 + NaCl were carried out at 700 °C. The results indicated that the composite coating performed better against the corrosion due to the gradient element distribution in Al-enriched outer layer and Cr-enriched inner layer. The corrosion mechanisms for the two coatings were also discussed.