Abstract: A chemical vapor deposition apparatus comprises a heating element capable of emitting electromagnetic radiation; a retort positioned relative to the heating element to receive the electromagnetic radiation; an encasing member at least partially disposed around the retort, the encasing member comprising a material that is at least partially transparent to the electromagnetic radiation; a plenum defined at least in part by an inner surface of the encasing member and an outer surface of the retort; and a furnace box at least partially disposed around the encasing member and the retort, and housing the heating element.

Abstract: A method of forming a metal coating on surfaces of internal passages of a turbine blade, the turbine blade having an outer surface and comprising at least one internal passage. The method includes injecting a paint into at least one of the internal passages of the turbine blade, and heat treating the turbine blade such that an aluminide coating is deposited on the surface of the at least one internal passage.

Abstract: Methods and apparatus for forming a metal coating on a surface of a workpiece are provided. The method includes positioning the workpiece in a microwavable chamber, positioning a coating material in the microwavable chamber, and heating at least the workpiece and the coating material using microwave range electromagnetic energy such that a diffusion coating of the coating material is formed on the surface of the workpiece.

Abstract: A method for preparing a protected article includes the steps of furnishing an article to be protected, wherein the article is a component of a gas turbine engine, thereafter depositing a precious-metal-containing layer onto the article, and thereafter depositing an aluminum-containing layer by vapor-phase aluminiding onto the article overlying the precious-metal-containing layer from an aluminum vapor source that includes a fluoride. The method further includes thereafter heating the article with the aluminum-containing layer deposited thereon in an atmosphere having at least 5 percent by volume hydrogen gas, and thereafter depositing a ceramic layer overlying the aluminum-containing layer.

Abstract: A surface of an article is protected by coating the surface with a silicon-containing coating by preparing a coating mixture of silicon, a halide activator, and an oxide powder, positioning the surface of the article in gaseous communication with the coating mixture, and heating the surface of the article and the coating mixture to a coating temperature of from about 1150° F. to about 1500° F. The article is preferably a component of a gas turbine engine made of a nickel-base superalloy.

Abstract: The present invention is process for forming diffusion aluminide coatings on an uncoated surface of a substrate, without interdiffusing a sufficient amount of aluminum into a coating layer to adversely affect the coating growth potential and mechanical properties of said coating layer. A metal substrate is provided comprising an external surface and an internal passage therein defined by an internal surface, at least a portion of the external surface of the substrate being coated with a coating layer selected from the group consisting of ?-NiAl-base, MCrAlX, a line-of-sight diffusion aluminide, a non-line-of-sight diffusion aluminide, a pack diffusion aluminide, and a slurry diffusion aluminide on said substrate. The external surface of the substrate is cleaned. The metal substrate is subjected to a aluminum vapor phase deposition process performed using a fluorine-containing activator selected from the group consisting of AlF3, CrF3, NH4F, and combinations thereof, at a rate in the range of about 0.