General Electric Company

Warren Davis Grossklaus, Jr

Melvin Robert Jackson

Richard Roy Worthing, Jr

John Matthew Powers

Lawrence Joseph Roedl

Brent Ross Tholke

Matthew Nicklus Miller

Jon Conrad Schaeffer

Joseph David Rigney

David Edwin Budinger

Richard John Grylls

Joshua L Miller

Thomas Froats Broderick

Patricia A Charles

Dewey D Dunkman

Petra Bracko

Ramgopal Darolia

Bin Wei

Lawrence Bernard Kool

Mark Daniel Gorman

Stephen Joseph Ferrigno

Roger Dale Wustman

Jeffrey Allen Conner

Mark Alan Rosenzweig

Howard John Farr

Jim D Reeves

John Robert LaGraff

Leo Spitz MacDonald

Joseph Howell Bowden, Jr

Earl L Kelly, Jr

Gilbert E Flowers

Melvin Howard Wilkins

Levi Williams

Gray W Grubbs

David Michael Matey

Timothy Lee Arney

Tris Colaizzi

Scott A Welsh

Jerald M Kauffman

Murray Sawyer Smith

Paul Wencil Stanek

James D Barber

Robert J Van Cleaf

Frederick S Kaempf

Eric C Hemsath

Randall L Hobbs

Michel Joseph Shaw

A method for joining a plurality of single crystal members includes providing a bonding foil with a composition match with that of the members and with a bonding temperature within the gamma prime solution temperature range of the members, but below the melting temperature of the foil and below the incipient melting temperature of the members. The foil is disposed between and in contact with opposing members to be joined while heated to and held at the bonding temperature for at least 10 hours.

Method for joining single crystal members and improved foil therefor

A method for repairing a nickel-base superalloy article, such as a gas turbine stationary flowpath shroud having flowpath cooling holes therein that has previously been in service, includes the steps of providing the nickel-base superalloy article that has previously been in service; and applying a restoration to a surface of the article. The restoration is applied by the steps of providing a restoration nickel-base alloy, wherein the restoration nickel-base alloy preferably has no more than about 15 weight percent chromium and no more than about 0.01 percent yttrium, thereafter applying a restoration coating of the restoration nickel-base alloy to the surface of the article by a hyper-velocity oxyfuel metal spray process or a low-pressure plasma spray process, and thereafter heating the article with the restoration coating applied to the surface thereof to a sufficiently high temperature to diffusion bond the restoration coating to the surface of the article. The article is then returned to service.

Method for HVOF or LPPS restoration coating repair of a nickel-base superalloy article

Formation of a silicon-modified aluminide coating on the under platform region of a superalloy gas turbine engine blade for improved corrosion and oxidation resistance. The coating is formed from a slurry composition including colloidal silica and aluminum-based powder and is substantially free of hexavalent chromium. The coating provides aluminum and silicon content in the outer 25% of a coating thickness of at least about 20% by weight aluminum and about 3% by weight silicon.

Methods for improving corrosion and oxidation resistance to the under platform region of a gas turbine blade

A damaged gas turbine blade which has previously been in service, and which is made of a base metal, is furnished. Any damaged material is removed from the damaged blade tip. The damaged blade tip is weld repaired with a nickel-base superalloy that is more resistant to oxidation resistance than is the base metal in the operating environment of the tip-repaired gas turbine blade. The method does not include any step of coating a lateral surface of the repaired blade tip with a non-ceramic coating after the step of weld repairing.

Repair of gas turbine blade tip without recoating the repaired blade tip

A method of repairing a turbine blade and the blade repaired thereby. The blade comprises a platform that has become bowed as a result of high temperature creep, with the result that the platform has a concave surface and an oppositely-disposed convex surface. The method generally comprises welding the concave surface to build up a weldment on the concave surface, cooling the weldment during which the weldment shrinks, the convex surface becomes flatter, and the concave surface beneath the weldment becomes flatter, and then removing a surface portion of the weldment so as to create a substantially flat weldment surface overlying the substantially straightened concave surface.

Method of repairing a turbine blade and blade repaired thereby

A nickel-base superalloy article, such as a gas turbine stationary flowpath shroud that has previously been in service, is repaired by applying a restoration coating to a surface of the article. The restoration coating is applied by providing a precursor mixture, wherein the precursor mixture has no more than about 15 weight percent chromium and no more than about 0.01 percent yttrium, and wherein the precursor mixture includes a higher-melting-point alloy component and a lower-melting-point alloy component. The precursor mixture is applied to the surface of the article, in a form such as a preform of the alloy components. The article with the precursor mixture applied to the surface thereof is heated to a sufficiently high temperature to melt the lower-melting-point alloy component, thereby forming the restoration coating on the surface of the article.

Method for repair of a nickel-base superalloy article using a thermally densified coating

An electrochemical process for selectively stripping at least one coating from the surface of a substrate is disclosed. The substrate (often a turbine engine component) is immersed in a composition through which electrical current flows. The composition includes a halide salt, such as sodium chloride, ammonium chloride, and potassium chloride. In preferred embodiments, the electrical current is direct current (DC). The process is especially useful for selectively removing portions of diffusion aluminide coatings. For example, the additive layer can efficiently be removed, without substantially affecting the underlying diffusion layer or substrate. Related stripping compositions and apparatuses are also described.

Method for partially stripping a coating from the surface of a substrate, and related articles and compositions

A stationary shroud of a gas turbine engine made of a base metal is repaired by removing any damaged material from a flow-path region of the stationary shroud to leave an initially exposed base-metal flow-path surface; and applying a base-metal restoration overlying the initially exposed flow-path surface. The base-metal restoration is applied by furnishing a source of a structural material that is compatible with the base metal, and depositing the source of the structural material overlying the initially exposed base-metal flow-path surface of the stationary shroud by plasma transferred arc welding to form a repaired base-metal flow-path surface. An environmentally resistant rub coating may be applied overlying the base-metal restoration.

Method of repairing a stationary shroud of a gas turbine engine using plasma transferred arc welding

The present invention provides for a squealer tip to include some proportion of a highly oxidation-resistant material, and a method for casting same, such that if any environmental coating were removed, the tip would retain some increased level of environmental resistance. The oxidation-resistant material optionally may also be a high abrasion resistance material, such that recession of the tip due to rubbing against a stator would be reduced. In a preferred embodiment, an abrasion-resistant and/or oxidation-resistant material is placed and suitably anchored into the tip region of a wax precursor used to cast a turbine airfoil. During the casting operation, the abrasion-resistant and/or oxidation-resistant material is not completely melted. As the alloy used to form the majority of the turbine blade solidifies, the abrasion and/or oxidation resistant material is incorporated into the turbine airfoil by the solidification of the alloy around it.

Oxidation resistant and/or abrasion resistant squealer tip and method for casting same

A method of repairing a thermal barrier coating on a component designed for use in a hostile thermal environment, such as turbine, combustor and augmentor components of a gas turbine engine. The method is particularly suited for completely removing a thermal insulating ceramic layer of thermal barrier coating system that includes a metallic bond coat, such as a diffusion aluminide or MCrAlY coating, between the surface of the component and the ceramic layer, while leaving the bond coat substantially undamaged. Furthermore, the method of this invention includes a technique by which ceramic material within cooling holes in the component can be removed without damaging the underlying bond coat. The process steps generally include removing the ceramic layer from the surface of the component by subjecting the ceramic layer to a caustic solution at an elevated temperature and pressure, and then removing ceramic material from the cooling hole by carefully directing a high-velocity fluid stream into the cooling hole. According to this invention, the high-velocity fluid stream is able to overcome the compressive stresses that otherwise anchor the ceramic in the cooling hole, yet does not remove or damage the bond coat underlying the ceramic.

Method for repairing a thermal barrier coating

A cast turbine airfoil to which a squealer tip is added. The turbine airfoil is cast slightly undersize. The squealer tip is comprised of an alloy that is different from the cast alloy of the airfoil, the oxidation resistance and strength of the squealer tip alloy being greater than the strength of the turbine airfoil alloy. The cast turbine alloy having the added squealer tip can utilize a material in the squealer tip that is more difficult to cast than the cast alloy material, yet is more suited for severe environmental conditions and temperature extremes.

Environmentally resistant squealer tips and method for making

A method for repairing the shroud surfaces of a gas turbine engine to provide corrosion and oxidation resistance of the shroud segments while also restoring the dimensional integrity of the shroud segments. The method entails removing the oxidation and corrosion products from the shroud segment, removing preexisting coating materials, applying a material compatible with the shroud segment substrate material, machining the surface, applying a corrosion-resistant, oxidation-resistant and rub-compliant material to the shroud segment using a HVOF process, machining the shroud segment to preselected dimensions and applying an aluminide coating for improved oxidation and corrosion resistance of the repaired surfaces.

Repair of high pressure turbine shrouds

A heating apparatus and method for welding a superalloy article. The apparatus and method of this invention provide for pre-weld and post-weld heat treatments to be performed on an article within the same enclosure in which the welding operation is performed. The apparatus accurately controls the temperature of the component to be welded throughout the temperature treatment profiles with the use of means for welding the article, means for heating the article, and means for sensing the article temperature. The apparatus also works in conjunction with a memory storage device that stores appropriate pre-weld and post-weld heat treatment temperature profiles and a welding temperature profile for the article.

Heating apparatus for a welding operation and method therefor

A nickel-base superalloy article which is susceptible to strain-age cracking and has a directionally oriented, single crystal, or equiaxed grain structure is repaired with minimal welding heat input into the article. The article is first heated to a welding temperature of from about 1650.degree. F. to about 2000.degree. F. in an inert atmosphere. A damaged area of the article is weld repaired using a plasma-transferred arc welder which vaporizes a filler metal in a plasma arc and deposited the vaporized metal onto the article to form a weld overlay. Minimal additional heat is added to the article during welding, as the weldment metal is vaporized remotely from the article.

Elevated-temperature, plasma-transferred arc welding of nickel-base

An apparatus and method for welding a superalloy article. The apparatus generally entails an enclosure adapted for containing a superalloy article, a polarity-reversing plasma transferred arc welder apparatus for welding a localized region of the article, an induction coil for heating the localized region, and elements for sensing and controlling the temperature of the localized region. The induction coil is placed in close proximity to the localized region of the article so that the temperature of the localized region is largely determined and quickly altered by the output of the coil. The polarity-reversing plasma transferred arc welding apparatus is operated at very low currents of not more than forty-five amps, so that the welding apparatus has only a secondary heating affect compared to the induction coil.

Welding method and apparatus therefor

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West Chester, OH, United States of America

Warren Davis Grossklaus, Jr