Abstract: A single-crystal article having a thermal barrier coating on a surface thereof, and a method for processing the article so as to promote the life of the coating. As a result of its single-crystal microstructure, the article is characterized by having been unidirectionally solidified along a primary crystallographic direction, and secondary crystallographic directions that are normal to the primary crystallographic direction. Improved spallation resistance of the coating is achieved by selectively orienting the secondary crystallographic direction with respect to a direction normal to a life-limiting surface region of the thermal barrier coating.

Abstract: An environmental coating and a method for forming the coating on a nickel aluminide component designed for use in a hostile thermal environment, such as turbine, combustor and augmentor components of a gas turbine engine. The environmental coating includes a metal that has been diffused into the surface of the nickel aluminide component, and an aluminum oxide layer on the surface of the nickel aluminide component. According to this invention, the metal is one or more noble metals, chromium and/or an MCr alloy, and forms a diffusion region comprising noble metal-aluminides and/or chromium-aluminides. The environmental coating optionally contains up to about 1.0 atomic percent of at least one oxygen-active element, such as yttrium, hafnium, zirconium and/or cerium. According to the invention, the environmental coating need only consist of the diffusion region and the aluminum oxide layer, and therefore does not require additional environmentally-resistant layers (e.g.

Abstract: An article having a protective coating thereon includes a substrate having a substrate composition and a substrate surface, and a protective coating contacting and overlying at least a portion of the substrate surface. The substrate is preferably a Ti--Nb aluminide, an .alpha.2-titanium aluiminide, or a .gamma.-titanium aluminide. The protective coating includes a metallic layer contacting the substrate surface and having a composition, in atomic percent, of from about 5 to about 40 percent chromium, from about 44 to about 59 percent aluminum, balance titanium plus incidental impurities. The protective coating may further include a ceramic layer contacting and overlying the metallic layer, with the metallic layer lying between the ceramic layer and the substrate.

Abstract: A method for manufacturing an article for use in a gas tubine engine is disclosed, which comprises applying a metallic bond coating on a superalloy substrate; surface doping a surface of the bond coating with at least one element selected from the group consisting of Fe, Cr and Y by plating, ion implantation, MOCVD and sputttering; and then applying an insulative ceramic coating on the bond coating.

Abstract: A thermal barrier coating adapted to be formed on an article subjected to a hostile thermal environment while subjected to erosion by particles and debris, as is the case with turbine, combustor and augmentor components of a gas turbine engine. The thermal barrier coating is composed of a metallic bond layer deposited on the surface of the article, a ceramic layer overlaying the bond layer, and an erosion-resistant composition dispersed within or overlaying the ceramic layer. The bond layer serves to tenaciously adhere the thermal insulating ceramic layer to the article, while the erosion-resistant composition renders the ceramic layer more resistant to erosion. The erosion-resistant composition is either alumina (Al.sub.2 O.sub.3) or silicon carbide (SiC), while a preferred ceramic layer is yttria-stabilized zirconia (YSZ) deposited by a physical vapor deposition technique to have a columnar grain structure.

Abstract: A bond-coated substrate is protected with an alpha alumina layer. The alpha alumina layer may be deposited as a relatively thick layer directly onto the bond-coated substrate. In this embodiment, no further ceramic layer overlies the alpha alumina layer. Other ceramics may be mixed into the alpha alumina layer, however. In another embodiment, a layer of a ceramic other than alpha alumina is deposited over the bond-coated substrate, and an alpha alumina layer is deposited over the ceramic layer.

Abstract: Chromium is deposited on a surface using a coating tape having a source layer including a powdered source of chromium, a solid reactant that reacts with solid chromium at elevated temperature to produce a gaseous chromium-containing compound, an inert powder dispersed with the powdered source of chromium, and a binder. Preferably, a porous media layer including a porous media material and a binder is affixed to the source layer. The coating tape is positioned adjacent to the surface of the substrate, with the porous media layer, where present, in contact with the surface. The coating tape and substrate are placed into a container, and the container is heated to elevated temperature in a non-oxidizing atmosphere. The gaseous chromium-containing compound is produced and chromium is deposited from the gaseous chromium-containing compound onto the surface of the substrate.

Abstract: A process is provided for manufacturing and repairing components, and particularly superalloy components such as gas turbine engine components. The invention entails forming precipitates in a surface of the article that has been cold worked as a result of surface machining, cleaning, handling, etc. The precipitates serve to prevent recrystallization and formation of a secondary reaction zone in the cold worked surface of the superalloy when subsequently exposed to temperatures approaching the solution temperature of the superalloy, such that the microstructure and mechanical properties of the superalloy article are preserved.

Abstract: A bearing includes a bearing component, such as a bearing race, having a bearing contact surface. A region at the bearing contact surface is made of titanium aluminide, preferably an alpha-2 or gamma titanium aluminide. A case-hardened layer present at the surface of the titanium aluminide region increases the hardness and wear resistance of the titanium aluminide at elevated temperature. The case-hardened layer is preferably formed by diffusing carbon into the surface of the titanium aluminide from a gaseous medium, at elevated temperature land at ambient or reduced pressure.

Abstract: An article of manufacture has as its basic structure a piece of a titanium aluminide, such as gamma (TiAl) or alpha-2 (Ti3Al), desirably in the shape of an aircraft gas turbine component. A thermal barrier coating system overlies at least a portion of the surface of the piece of titanium aluminide. The thermal barrier coating system includes a metallic bond coat layer, preferably in the form of a layer of a nickel-based alloy no more than about 0.005 inches thick, that contacts the piece of titanium aluminide, and a ceramic thermal barrier coating layer, preferably a stabilized zirconia such as yttria-stabilized zirconia, overlying the bond coat.

Abstract: A catalyst-bearing component of a gas turbine engine is provided. Catalytic materials are provided on components defining the gas flow path of the engine, so that emissions of carbon monoxide and unburned hydrocarbons are reduced. The catalytic materials are selected from the group consisting of noble metals and transition metal oxides. The portions of the gas flow path where such materials are advantageously applied include the combustor, the turbine and the exhaust system. The catalytic coating is preferably applied in conjunction with a thermal barrier coating system interposed between a substrate component and the catalytic coating.

Abstract: A superalloy article has a nickel-based superalloy substrate containing TCP-phase forming elements such as rhenium, chromium, tantalum and tungsten. A carbide precipitate-containing region is formed within the substrate extending to a carbide depth below a surface of the substrate, preferably by depositing carbon on the surface of the substrate and diffusing the carbon into the substrate. An aluminum-rich diffusion layer extends from the surface of the substrate to an aluminide depth below the surface of the substrate. Preferably, the carbide depth is about the same as the aluminide depth. The presence of the carbide precipitates inhibits the formation of the deleterious TCP-phase.