Method of forming a diffusion aluminide-hafnide coating
AssigneeGeneral Electric Company
InventorsNripendra N. Das, Thomas E. Mantkowski, Raymond W. Heidorn, Joshua L. Miller, Jeffrey A. Pfaendtner
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Abstract
A process for forming a diffusion aluminide-hafnide coating on an article, such as a component for a gas turbine engine. The process is a vapor phase process that generally entails placing the article in a coating chamber containing a halide activator and at least one donor material. The donor material collectively consists essentially of at least 0.5 weight percent hafnium and at least 20 weight percent aluminum with the balance being chromium and/or cobalt.
Claims20
A process for forming a diffusion aluminide-hafnide coating, the process comprising the steps of:
- placing an article in a coating chamber containing a halide activator and at least one donor material, the donor material collectively consisting essentially of at least 0.5 weight percent hafnium and at least 20 weight percent aluminum with the balance being a material with a higher melting point than aluminum, both the hafnium and the aluminum being available at the surfaces of the donor material, the article being out of contact with the halide activator and the donor material;
- and then
- in an inert or reducing atmosphere, heating the article, the halide activator and the donor material to react the hafnium and aluminum at the surfaces of the donor material with the halide activator and produce a halide vapor that reacts at the surface of the article to form a diffusion aluminide-hafnide coating on the surface.
A process for forming a diffusion aluminide-hafnide coating on a superalloy component of a gas turbine engine, the process comprising the steps of:
- placing the superalloy component in a coating chamber containing at least one donor material and a halide activator, the halide activator being present in an amount sufficient to achieve a level of activator activity equal to about 0.7 to about 2.4 moles of AlF3 per cubic foot of coating chamber volume, the donor material collectively consisting essentially of at least 0.5 to about 10 weight percent hafnium, at least 20 to about 55 weight percent aluminum, the balance chromium or cobalt, both the hafnium and the aluminum being available at the surfaces of the donor material, the component being out of contact with the halide activator and the donor material;
- and then
- in an inert or reducing atmosphere, heating the component, the halide activator and the donor material to at least 980° C. for a duration of at least three hours, so that the hafnium and aluminum of the donor material react with the halide activator and produce a halide vapor that reacts at the surface of the component to form a diffusion aluminide-hafnide coating on the surface;
- wherein the relative amounts of hafnium and aluminum available at the surfaces of the donor material are selected to determine the relative amounts of hafnium and aluminum in the difflusion aluminide-hafnide coating.
Dependencies are inferred from the claim text.