Oxidation Performance and Interdiffusion Behavior of a Pt-Modified Aluminide Coating with Pre-deposition of Ni

Abstract

To refrain the interdiffusion of elements while holding good oxidation resistance, a (Ni,Pt)Al/Ni composite coating was prepared by sequential treatments of electroplating Ni and Pt and successive gaseous aluminization. In comparison with normal (Ni,Pt)Al coating, high-temperature performance of the composite coating was evaluated in isothermal oxidation test at 1100 °C. Both the two coatings exhibited good resistance against high-temperature oxidation, but the interdiffusion of elements between composite coating and single-crystal (SC) superalloy substrate was greatly relieved, in which the thickness of secondary reaction zone (SRZ) and the amount of precipitated topologically close-packed phase in the SC alloy matrix were significantly decreased. Mechanisms responsible for delaying rate of coating degradation and SRZ growth/propagation are discussed.