Microstructure and isothermal oxidation resistance of Thermal Barrier Coatings deposited by LPPS, CVD and PS-PVD methods on Inconel 617 nickel superalloy

摘要

The paper presents results of research into thermal barrier coatings characterized by high oxidation resistance which are presently used in the aerospace industry. Bond coat were formed by overaluminizing of the MCrAlY coating, deposited by low pressure plasma spraying (LPPS). The top coat of yttria-stabilized zirconia was deposited by plasma spray physical vapour deposition (PS-PVD). For comparison purposes additionally formed were MCrAlY bond coat, which were not subsequently aluminized. The investigation showed that during CVD overaluminizing there was formed an additional layer built of the β-NiAl phase, which protects substrate from oxidation. High chromium content in the substrate provides hot corrosion resistance. The top coat was characterized by columnar structure, similar to that obtained in the EB-PVD process. The isothermal oxidation tests showed that thickness of the TGO layer into overaluminized bond coat was significantly thicker in comparison with conventional LPPS-sprayed MCrAlY bond coat.