Microstructure and oxidation resistance of a Si doped platinum modified aluminide coating deposited on a single crystal superalloy

Abstract

A Si doped Pt modified aluminide coating was prepared by electroplating and the chemical vapour deposition method. The microstructure and oxidation resistance of the coating were studied, with a single Pt modified aluminide coating as a reference. The results showed that the Si doped Pt modified aluminide coating consisted of singular β-(Ni, Pt)Al phase, and no PtAl2 phase was detected, which might be due to the fact that the addition of Si retarded the formation of PtAl2 phase in the outer layer. Si was dissolved in the β-(Ni, Pt)Al phase in the outer layer and might form silicide with refractory elements in the inter-diffusion zone. The Si doped Pt modified aluminide coating possesses a better oxidation resistance than the Pt modified aluminide coating since Si could promote the formation of α-Al2O3 and inhibit the diffusion of the refractory elements, reducing the formation of detrimental volatile phase.