Abstract: An article is coasted by preparing a coating source having an aluminum halide, a fluoride or an iodide of a modifying element as a source of the modifying element, and a carrier gas. The modifying element is zirconium, hafnium, and yttrium, or combinations thereof. The coating source is contacted to the article, and the coating source and the article are heated to a coating temperature of at least about 1850° F. for a period of time sufficient to permit aluminum and the modifying element to coat onto the surface of the article. The preferred fluorides of modifying elements are zirconium tetrafluoride and hafnium tetrafluoride.

Abstract: A turbine blade is coated by first applying a particle-entrapped tip coating to the tip of the airfoil. An aluminum-containing coating is thereafter applied to the airfoil, including to the tip of the airfoil overlying the particle-entrapped tip coating. The aluminum-containing coating is applied by providing a source of aluminum contacting the airfoil that deposits aluminum onto the airfoil at a coating temperature, and heating the airfoil to the coating temperature so that the aluminum-containing coating is deposited onto the airfoil, and so that the aluminum-containing coating and the particle-entrapped tip coating are diffused into the turbine blade substrate. The step of applying the aluminum-containing coating occurs without substantial prior interdiffusing of the particle-entrapped tip coating with the tip of the airfoil as a separate step.

Abstract: A method for accurately sizing and forming the cooling holes of an air-cooled gas turbine engine component on which a protective diffusion coating will be deposited. The method generally entails drilling a hole in a surface region of a substrate, and then measuring the thickness of any recast surface region surrounding the hole and created as a result of a portion of the surface region having melted and then resolidified. The thickness of the additive layer of the diffusion coating that will deposit on a corresponding recast surface region of the component is then predicted based on an inverse relationship determined to exist with the thickness of the recast surface region formed during drilling of the cooling hole. An appropriately-oversized hole can then be formed in the component so that, after depositing the diffusion coating on the component, the additive layer grows sufficiently within the hole to yield a cooling hole approximately having the required final diameter.