Abstract: Oxidation resistant components and methods for creating an aluminum diffusion surface layer within substantially nickel- and cobalt-free components are disclosed. An aluminum-containing slurry may be applied to a component. The component may then be heated to diffuse aluminum into the component and to form an aluminum diffusion surface layer therein. The surface layer may be characterized by an intermetallic aluminum-containing phase extending below the surface of the component.

Abstract: A method and composition are provided for coating honeycomb seals and, more specifically, to a method and slurry for applying an aluminide coating onto honeycomb seals. The method includes preparing a slurry of a powder containing a metallic aluminum alloy having a melting temperature higher than aluminum, an activator capable of forming a reactive halide vapor with the metallic aluminum, and a binder containing an organic polymer. The slurry is applied to surfaces of the honeycomb seal, which is then heated to remove or burn off the binder, vaporize and react the activator with the metallic aluminum to form the halide vapor, react the halide vapor at the substrate surfaces to deposit aluminum on the surfaces of the seal, and diffuse the deposited aluminum into the surfaces to form a diffusion aluminide coating.

Abstract: In one embodiment, a method for forming an aluminide coated article comprises: applying an aluminum composition to the article to form a precursor coating, heating the article to a migration temperature sufficient to diffuse a metal from the article into the precursor coating, and gasifying aluminum in the aluminum composition at a gasification temperature that is greater than or equal to the migration temperature. An outward grown aluminide coating forms on the article. In another embodiment, a method for forming an aluminide coated article, comprises: applying an aluminide composition an article to form a precursor coating, heating the article to a migration temperature of greater than or equal to 1,065° C., gasifying the aluminum at a gasification temperature of greater than or equal to 1,065° C., and forming an outward grown aluminide coating on less than 100% of a surface of the article.

Abstract: A slurry and slurry coating process for forming a diffusion aluminide coating on a substrate, including internal surfaces within the substrate. The process involves preparing a slurry of a powder containing a metallic aluminum alloy having a melting temperature higher than aluminum, an activator capable of forming a reactive halide vapor with the metallic aluminum, and a binder containing an organic polymer. The slurry is applied to surfaces of the substrate, which is then heated to burn off the binder, vaporize and react the activator with the metallic aluminum to form the halide vapor, react the halide vapor at the substrate surfaces to deposit aluminum on the surfaces, and diffuse the deposited aluminum into the surfaces to form a diffusion aluminide coating. The process can be tailored to selectively produce an inward or outward-type coating. The binder burns off to form an ash residue that can be readily removed.

Abstract: In one embodiment, a method for forming an article with a diffusion portion comprises: forming a slurry comprising chromium and silicon, applying the slurry to the article, and heating the article to a sufficient temperature and for a sufficient period of time to diffuse chromium and silicon into the article and form a diffusion portion comprising silicon and a microstructure comprising ?-chromium. In one embodiment, a gas turbine component comprises: a superalloy and a diffusion portion having a depth of less than or equal to 60 ?m measured from the superalloy surface into the gas turbine component. The diffusion portion has a diffusion surface having a microstructure comprising greater than or equal to 40% by volume ?-chromium.