United Technologies Corporation

Charles C McComas

Larry S Sokol

Earl M Hanna

James W Morris

Brian A Manty

John W Appleby, Jr

Gerard A Sileo

Kenneth C Long

Dennis C Stewart

Herbert R Barringer

Michael J Patry

A method is taught for application of an abrasive tip to a gas turbine blade by brush plating, wherein particulate abrasive is applied to the tip of said blade and held in position during electroplating by a porous dielectric cloth.

Brush plating compressor blade tips

Gas turbine engine coatings must often be removed during engine maintenance and repair. The techniques utilized to accomplish this task, machining, chemical stripping, machining followed by chemical stripping, or grit blasting, frequently result in component damage or destruction. Liquid jet erosion can be utilized to remove seals, coatings, or portions thereof without damaging the engine hardware.

Liquid jet removal of plasma sprayed and sintered

Adverse interactions during initial interactions between abradable seal components are minimized by applying a coating to the moving seal component. The coating is nonreactive with the abradable material and provides lubricity during initial seal operation.

Method of coating abradable seal assembly

Removal of ceramic thermal barrier coatings from metallic substrates is achieved by contacting the coated article with fluorine containing gas at an elevated temperature. The gas penetrates the ceramic to attack the interface between the substrate and ceramic causing the ceramic to spall.

Gaseous removal of ceramic coatings

Methods of repairing defects in superalloy articles are described. Defective areas are cleaned and prepared to expose clean substrate surfaces. A layer of superalloy powder material containing a melt depressant (boron) is applied. A layer of superalloy material essentially free from boron is then applied. The dual coated article is heated to a temperature at which the boron containing layer melts, but the boron-free layer does not. The boron diffuses into the substrate raising the melting point of the molten material until solidification results. The unmelted surface layer is subsequently removed leaving behind a repaired article free from surface defects.

Repair of surface defects in superalloy articles

A protectively coated superalloy has improved oxidation, corrosion, and wear resistance at elevated temperatures. The protective coating is a MCrAlY type alloy having a carbon content of 0.6 to 11 percent and is characterized in a preferred embodiment by having a carbon bearing matrix containing metal carbides of 1-2 microns mean size and chromium carbides of less than 12 microns. The coating is preferredly produced by plasma spraying and heat treatment.

Carbon bearing MCrAlY coating

A method of applying a wear resisting MCrAlY coating is comprised of plasma spraying a mixture of MCrAlY and Cr.sub.3 C.sub.2 powders to form a coating having both fine carbides and coarser Cr.sub.3 C.sub.2 carbides in an MCrAlY matrix. Heat treatment at 1080.degree. C. after coating bonds the substrate and coating and forms further fine carbides. The coating desirably consists of by weight percent 18-80 Cr, 1.2-29 Al, up to 4.8 Y, 0.6-11 C, balance selected from the group consisting of Ni, Co, Fe, or mixtures thereof.

Process for carbon bearing MCrAlY coating

A method of adhering a ceramic facing material to an underlying substrate is disclosed. Substrates to which the concepts apply include unsupported low modulus, porous wire pads as well as low modulus, porous wire pads backed by a solid metallic form. The ceramic application techniques employed are centered around the impregnation of the regions of the pad to be ceramic coated with an underlayment coating, such as MCrAlY material, wherein the designation 'M' stands for at least one of the elements from the iron cobalt and nickel group. Deep penetration of the underlayment material into the pad is achieved with a high velocity, spraying process. Ceramic material is applied over the underlayment material by conventional spraying techniques. Articles of manufacture which are suited to fabrication in accordance with the concepts disclosed herein include, but are not limited to, outer air seals, combustion chambers, and airfoils of gas turbine engines.

Ceramic faced structures and methods for manufacture thereof

A plasma spray method capable of directing plasticized powders against a substrate for deposition of a protective coating thereon is disclosed. Various structural details of the apparatus described enable the attainment of high particle velocities without melting the particles. The technical concepts employed are directed to normalizing the temperature of the plasma stream at a reduced value prior to the injection of coating particles. A general reduction in temperature and substantial elimination of a thermal spike at the core of the stream are achieved. Coating particles are injected into the plasma stream only after the plasma is first cooled and then preferably accelerated. In detailed embodiments, a nozzle extension assembly having a plasma cooling zone, a plasma acceleration zone, a powder injection zone and a plasma/powder discharge zone is affixed to the downstream end of a conventional plasma generator.

Plasma spray method and apparatus

Thermal spray apparatus capable of directing plasticized powders against a substrate for deposition of a protective coating thereon is disclosed. Various structural details of the apparatus of the present invention enable the attainment of high particle velocities without melting the particles. The apparatus is built around the concept of reducing the temperature of a hot plasma stream after the hot plasma stream is generated. Particles are injectedinto the hot plasma stream only after the medium is cooled. In detailed embodiments, a generated plasma is cooled by the addition of a diluent gas or by passing the generated plasma through an elongated heat exchanger upstream of the point at which the powders are to be injected.

Thermal spray apparatus

A thermal spray method capable of directing plasticized powders against a substrate for deposition of a protective coating thereon is disclosed. Various structural details of the apparatus described enable the attainment of high particle velocities without melting the particles. The method is built around the concept of reducing the temperature of a hot plasma stream after the hot plasma stream is generated. Coating particles are injected into the hot plasma stream only after the medium is cooled. In detailed embodiments, a generated plasma is cooled by the addition of a diluent gas or by passing the generated plasma through an elongated heat exchanger upstream of the point at which the powders are to be injected. The plasma is accelerated after the plasma is cooled to recover velocity lost in the cooling step.

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Stuart, FL, United States of America

Charles C McComas