Abstract: A coating system and method for forming the coating system on an article designed for use in a hostile environment, such as the superalloy turbine, combustor and augmentor components of a gas turbine engine. The method employs a nitrided zone in the surface of the superalloy substrate to inhibit the formation of deleterious topologically-close packed (TCP) phases in the substrate when protected by an aluminum-rich coating and optionally a thermal insulating ceramic layer. Superalloys of particular interest are those containing significant levels of TCP phase-forming elements, such as tungsten, rhenium, tantalum, molybdenum and chromium.

Abstract: A method for producing a thermal barrier coating system on an article that will be subjected to a hostile environment. The thermal barrier coating system is composed of a metallic bond coat and a ceramic thermal barrier coating having a columnar grain structure. The method generally entails forming the bond coat on the surface of a component, and then grit blasting the bond coat with an abrasive media having a particle size of greater than 80 mesh. The component is then supported within a coating chamber containing at least two ingots of the desired ceramic material. An absolute pressure of greater than 0.014 mbar is established within the chamber containing oxygen and an inert gas. Thereafter, the ceramic ingots are vaporized with an electron beam such that the vapor deposits on the surface of the component to form a layer of the ceramic material on the surface.

Abstract: A method is provided for enhancing to a selected coating range a substantially unused protective coating, including aluminum, on an article surface, for example an airfoil surface of a gas turbine engine turbine blade. The protective coating is enhanced without removing such unused coating. The unused coating is evaluated to identify at least one coating region that deviates from the selected coating range by being deficient in at least one of chemistry and physical condition, for example thickness. At least the coating region is enhanced to the selected coating range by applying over the identified coating region at least one secondary element selected from Pt, Rh, Pd, Cr, Si, Hf, Zr, and Y. At least the coating region is heated to diffuse the secondary element into the protective coating to provide a treated coating region. Then at least the treated coating region is aluminided.

Abstract: A structure includes a cooled article having an open-cell solid foam of ceramic or metal cell walls with a porous interconnected intracellular volume therebetween. A source of a pressurized gas is in communication with a source region of the cooled article. The source of the pressurized gas includes a gas plenum in gaseous communication with the source region, and a compressor having a compressed gas output in gaseous communication with the gas plenum. Gas flows from the source of the pressurized gas through the porous intracellular volume, to cool the cooled article.

Abstract: An article is formed of a single crystal having a composition, in weight percent, of a modifying element in an amount of from about 0.2 to about 2.0 percent by weight hafnium, from about 0.1 to about 0.5 percent by weight zirconium, or combinations thereof, and a base alloy composition of from about 4 to about 20 percent cobalt, from about 1 to about 10 percent chromium, from about 5 to about 7 percent aluminum, from 0 to about 2 percent molybdenum, from about 3 to about 8 percent tungsten, from about 4 to about 12 percent tantalum, from 0 to about 2 percent titanium, from 0 to about 8 percent rhenium, from 0 to about 6 percent ruthenium, from 0 to about 1 percent niobium, from 0 to about 0.1 percent carbon, from 0 to about 0.01 percent boron, from 0 to about 0.1 percent yttrium, and balance nickel and incidental impurities.

Abstract: A nickel-base superalloy article substrate has more nickel than any other element, a reactive element that is hafnium, zirconium, yttrium, lanthanum, or cerium, or combinations thereof, and a nominal bulk composition of carbon. A protective layer is deposited overlying the surface of the article substrate. The depositing of the protective layer includes steps of decarburizing locations where the carbon serves as a barrier to the diffusion of the reactive element from the substrate into the protective layer, and depositing an aluminum-containing protective layer overlying the substrate. The decreasing of the carbon concentration may be accomplished by decarburizing the substrate, depositing a platinum-containing layer and then decarburizing, depositing an aluminum-containing layer in a reducing atmosphere, or decarburizing the deposited protective layer. A ceramic thermal barrier coating may be deposited overlying the protective layer.

Abstract: A coating system for Si-containing material, such as those used to form articles exposed to high temperatures, including the hostile thermal environment of a gas turbine engine. The coating system is a compositionally-graded thermal/environmental barrier coating (T/EBC) system that exhibits improved mechanical integrity for high application temperatures that necessitate thick protective coatings. The T/EBC system includes an intermediate layer containing YSZ and BSAS, mullite and/or alumina, which is preferably used in combination with a mullite-containing layer that overlies the surface of the Si-containing material, a layer of BSAS between the mullite-containing layer and the intermediate layer, and a thermal-insulating top coat of YSZ overlying the intermediate layer.

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 gas turbine stationary shroud is a curved stationary shroud body having a concave inner gas-path surface and a generally convex back. The curved stationary shroud body is made of an open-cell solid ceramic foam having ceramic cell walls with intracellular volume therebetween. The ceramic foam may be tailored to provide requirement properties. The ceramic adjacent to the gas path surface may be modified to increase or decrease its abrasion resistance, depending upon the design requirements of the stationary shroud. The intracellular volume adjacent to the gas-path surface may be porosity. Some of the ceramic material adjacent to the back of the shroud may be removed, and the intracellular volume adjacent to the back of the shroud may be filled with a nickel-base alloy.

Abstract: A gas injector system includes a plenum with a plenum opening in the wall of the plenum. An injector is positioned at a location overlying the plenum opening. The injector includes a injector block affixed to the exterior surface of the plenum wall, a joint between the injector block and the plenum wall, and an angularly inclined injector passage extending through the injector block from an injector passage inlet to an injector passage outlet. The injector block is preferably brazed to the plenum wall for high-temperature applications, or adhesively joined for low-temperature applications.

Abstract: A method is provided for repairing an article having a fissure in a metallic overlay environmental resistant coating that includes the element Al, for example an overlay coating of the MCrAlY type. The method depletes more than about 90 wt. % of the Al from an exposed coating surface within the fissure and from a coating outer surface adjacent the fissure, to a depth of at least about 7 mils, without removal of the coating and while substantially maintaining the coating thickness. Thereafter, the fissure is repaired.

Abstract: A diffusion aluminide coating having a graded structure is applied over a nickel base superalloy substrate. The coating has an inner region of a diffusion aluminide adjacent to the substrate rich in a reactive element, typically Hf, Si or combinations of the two. The near surface region is a diffusion aluminide which is substantially free of reactive elements. Such coatings when used as bond coats in thermal barrier coating systems exhibit improved spallation performance.

Abstract: A flexible tool that fits over the pressure or concave side of a metallic airfoil that includes a lightweight material component for a gas turbine engine during the fabrication of the airfoil. The metallic fan airfoil includes pockets or cavities that have been machined into the airfoil in order to reduce the weight of the airfoil. The tool is a flexible body manufactured from sheets of composite material and includes an integral elastomeric seal. The tool is placed over the airfoil and forms a seal against the pressure side of the airfoil so that lightweight resin can be injected into the pockets and retained in position during curing. The flexible tool is formed by laying up thin sheets of composite material that includes fiber over a metallic master tool after partially cured elastomeric material is placed inside a marking corresponding to the airfoil perimeter.

Abstract: A protective structure includes a substrate made of a nickel-base superalloy component of a gas turbine engine, and a ceramic thermal barrier coating overlying and bonded to the substrate. The ceramic coating is an open-cell solid foam of aluminum oxide ceramic cell walls having a porous interconnected intracellular volume therebetween. The ceramic coating is prepared by depositing a precursor material onto the surface of the substrate. The precursor material includes a sacrificial ceramic, typically silicon dioxide, and a reactive metal, typically aluminum, which is reactive with the sacrificial ceramic to form an open-celled ceramic foam. The sacrificial ceramic and the reactive metal are reacted together to form ceramic cell walls of an oxidized ceramic of the reactive metal, preferably aluminum oxide, and an interconnected intracellular volume therebetween filled with an intracellular metal. The intracellular metal is thereafter removed to leave a porous intracellular volume.

Abstract: A method of removing a core from a CMC component in which the core was used to form an internal cavity. According to one embodiment of the invention, the core is removed from a fully densified CMC component by heating the component and core to a temperature at which the core deteriorates but below a temperature at which the component would melt or otherwise be damaged. According to a second embodiment of this invention, the component is only partially densified, and then impregnated with a coating material that is resistant to a leaching compound capable of removing the core. The core can then be removed using the leaching compound without damage to the internal surfaces of the component defined by the core when the component was fabricated.

Abstract: A gas turbine component article has an airfoil section and is formed of a nickel-base superalloy. An unmasked region of the airfoil section has a platinum aluminide protective coating, and a masked region of the airfoil section has an aluminide coating. The platinum aluminide preferably is deposited at a trailing edge of the airfoil section that is susceptible to low-cycle fatigue damage when a platinum aluminide coating is present.

Abstract: Abradable coatings for turbine engine shrouds are formed from biscuits formed of silicon-diffused powdered alloy compositions which are processed with an HF precursor to strip oxides from the coating during processing, the alloy blends comprising MCrAl(Y)n alloys in which n is 0, 1 or more.

Abstract: A method of adjusting airflow through a plurality of cooling holes by depositing a thermal barrier coating on an exterior surface and/or an interior surface of the component by a physical vapor deposition process. The cooling holes are not masked. Thus, a portion of the thermal barrier coating partially obstructs airflow through the cooling holes and reduces airflow through the cooling holes. A predetermined pressure drop is developed across the cooling holes and airflow through the cooling holes is measured. The measured airflow is compared to a preselected range of desired cooling hole airflows and the steps of depositing the thermal barrier coating, developing the predetermined pressure drop, calculating airflow and comparing the measured airflow to the preselected range are repeated until the measured airflow is within the preselected range of desired cooling hole airflows.

Abstract: A method for producing a turbine airfoil that is coated with a beta phase, high aluminum content coating, such as substantially stoichiometric NiAl, and which has a surface finish suitable for application of a ceramic topcoat. The method involves impacting the coating with preselected particles of a preselected size so that the brittle coating is not adversely affected by chipping or breakage. The impacting produces a surface finish of 120 micro-inches or better so that a ceramic thermal barrier layer can be applied over the coating. The preferred method of improving the surface finish utilizes steel balls having a diameter of about 0.033″ and a peening intensity of no greater than about 6 A.

Abstract: A tightly adherent anti-stick coating applied over coated turbine components of gas turbine engines. The tightly adherent coating is an oxide of at least one metal selected from the group consisting of Pt, W, group 4b and group 5b metals of the periodic table and Si, Ge and Sn of group 4a. The oxide is applied directly over existing environmental coatings, and thermal barrier coatings. It can also be applied directly to substrate material and to areas that are not within the combustion exhaust gases, such as platform portions and shank portions of airfoils including turbine blades. The oxide is conveniently applied to a uniform thickness of no greater than about 10 microns, and prevents the build-up of corrosion products and other products of combustion from the gases, thereby increasing the life expectancy of the component.