Low-temperature formation and oxidation resistance of nickel aluminide/nickel hybrid coatings on alloy steels

Conditions were identified for low-temperature formation of a hybrid coating consisting of an outer nickel aluminide layer and an inner nickel layer on alloy steels using a two-step process of nickel plating followed by pack aluminization. The long-term oxidation process of the coating in air at 650 °C did not obey any power laws of oxidation, but can be described by logarithmic kinetics. Factors affecting the lifetime of the coating at 650 °C were delineated.