Research Progress of Element Modified Aluminide Coatings

Abstract

Aluminide coatings have become an important thermal protection coating for the hot-end components of gas turbines.This is due to its ability to form an Al2O3 film when in high-temperature service，which effectively improves the components’resistance to high-temperature oxidation and thermal corrosion，thereby prolonging their service life.However，the phase transition of the aluminum-rich β-NiAl phase to the aluminum-poor γ-Ni3Al phase of the single aluminide coating is prone to occur during service，which reduces the Al content in the coating and makes it difficult for the coating to continuously form a dense Al2O3 film.In this paper，the use of element modification (such as Si，Cr，Co，Pt，Pd，and rare earth elements) to improve the high-temperature oxidation and thermal corrosion performance of aluminide coatings was summarized.Among these，the Pt element was found to simultaneously promote the oxidation of the Al element into dense Al2O3 film and improve the anti-peeling ability of the oxide film，thus having the best modification effect on the high-temperature performance of the aluminide coating.Based on the effect of single-element modification，the researchers developed multiple elements (binary and ternary) co-modified aluminide coatings.The performance of aluminide coatings could be improved more effectively by the co-modification of Pt and elements that hindered the diffusion of elements between the coating and the substrate or inhibited phase change elements.Finally，the future development trend of modified aluminide coatings might have been higher co-modification (quaternary and pentagonal) of Pt with rare earth or other elements.

Keywords

• aluminide coating|element modification|high temperature oxidation|hot corrosion