M-CrAlY Bond Coats For Single And Double Layer TBCs Applied By LPPS Or HVOF

MCrAlY powders are deposited by Low-Pressure-Plasma-Spray (LPPS) or alternatively by High-Velocity-Oxygen-Fuel (HVOF) as a protective coating or as a bondcoat in TBC systems on hot-section-parts of gas-turbine components.

The high-temperature behavior as oxidation or hot corrosion of MCrAlY coatings is affected by the thermal spray process used to deposit the protective layer. The protective life of MCrAlY coatings depends on the formation of the alumina scale and the loss of the aluminum within the coating either by diffusion due to high-temperatures or by the protective scale formation.

The aim of the present investigation, carried out as a part of a long-term study on MCrAlY coatings, is to provide a comparison of bond coats deposited by LPPS and HVOF. NiCoCrAlY and CoNiCrAlY coatings were used as bondcoats for APS sprayed TBCs (single and double-layer). The high temperature resistance of these TBC systems was evaluated by isothermal and thermal cycling oxidation tests.