Abstract: Method and apparatus for repairing an article, such as an air-cooled component, during which at least a portion of the component must be removed and replaced. The method and apparatus make use of one or more workpiece holders adapted to secure and position an component on the apparatus, a multi-axis head adapted for movement relative to the workpiece holder, a nozzle mounted to the multi-axis head and operable to remove at least a portion of the component with a jet of fluid discharged therefrom, an electrical-discharge electrode mounted to the multi-axis head and operable to form surface holes in the component by electrical-discharge machining, and a system for controlling the movement of the multi-axis head so that the waterjet and electrical-discharge machining operations are performed to yield a repaired component that closely duplicates the original.

Abstract: A stainless steel alloy that exhibits both high strength and toughness as a result of having particular ranges for chemistry, tempering temperatures and grain size. The alloy is a precipitation-hardened martensitic stainless steel with an ultimate tensile strength of at least 1200 MPa, a Charpy impact toughness of greater than 55 J, and a grain size of ASTM 5 or finer. The alloy consists essentially of, by weight, 14.0 to 16.0 percent chromium, 6.0 to 7.0 percent nickel, 1.25 to 1.75 percent copper, 0.5 to 1.0 percent molybdenum, 0.03 to 0.5 percent carbon, niobium in an amount by weight of ten to twenty times greater than carbon, the balance iron, minor alloying constituents and impurities.

Abstract: A process for depositing a ceramic coating system for Si-containing materials, particularly those for articles exposed to high temperatures. The process is particularly applicable to depositing a compositionally-graded coating system comprising multiple ceramic layers with differing compositions, including a dense, strain-tolerant, vertically-cracked YSZ-containing ceramic layer deposited on a ceramic layer having a composition that is a mixture of YSZ and either mullite or BSAS. The process entails depositing the YSZ-containing ceramic layer using a plasma spraying technique while maintaining the substrate at a temperature so as not to form horizontal cracks in the coating system, but still maintain the dense vertically-cracked structure of the YSZ-containing ceramic layer for strain tolerance.

Abstract: A castable and weldable nickel-base alloy that exhibits a desirable balance of strength and resistance to corrosion and oxidation suitable for gas turbine engine applications. A suitable composition for the alloy consists essentially of, by weight, 10% to 25% cobalt, 20% to 28% chromium, 1% to 3% tungsten, 0.5% to 1.5% aluminum, 1.5% to 2.8% titanium, 0.8% to 1.45% columbium, tantalum in an amount less than columbium and Cb+0.508Ta is 1.15% to 1.45%, 0.001% to 0.025% boron, up to 0.4% zirconium, 0.02% to 0.15% carbon, with the balance essentially nickel and incidental impurities.

Abstract: An overlay welding apparatus for depositing an overlay weld on rotating tube stock. The apparatus comprises an elongate frame and supports for rotating the tube stock about a central axis thereof. The tube stock is inclined relative to horizontal when supported by the supports, such that improved cooling is achieved with a cooling medium delivered to the interior of the tube stock as the tube stock rotates. The apparatus further comprises a welding carriage mounted to the frame and adapted for travel along the frame. The welding carriage supports an overlay welding head for depositing an overlay weld on a surface region of the tube stock as the tube stock is rotated, and supports a wash welding head for reducing a heat-affected zone in the surface region as the tube stock is rotated. A steady rest is mounted adjacent the welding carriage for movement with the welding carriage along the frame.

Abstract: A method and system for nondestructively detecting and characterizing defects in articles, including assemblies that may include components formed of composite materials. The method entails vibrating an entire article/assembly to induce an oscillating strain in the article/assembly so that any flaws in the article/assembly are heated by localized friction, as would occur between opposing surface portions of a defect or an interface between components of the assembly. The article/assembly is then infrared imaged to detect any localized temperature rises associated with the localized friction at the defect or interface.

Abstract: A process for welding superalloys, and particularly articles formed of gamma prime-strengthened nickel-base superalloys whose chemistries and/or microstructures differ. The process entails forming the faying surface of at least one of the articles to have a cladding layer of a filler material. The filler material may have a composition that is different from both of the articles, or the same as one of the articles. The cladding layer is machined to promote mating of the faying surfaces, after which the faying surfaces are mated and the articles welded together. After cooling, the welded assembly is free of thermally-induced cracks.

Abstract: A method of forming a welded assembly, wherein an electron beam is used to form a weldment that joins two or more articles to form the welded assembly. The method involves directing a second electron beam onto the weldment in the wake of the welding beam, in a manner that inhibits precipitation of a solutioned precipitation-strengthening phase so as to reduce the incidence of strain-age cracking in the weldment.

Abstract: A component formed at least in part by a CMC material and equipped with an integrally-formed surface feature, such as an airflow enhancement feature in the form of a turbulator or flow guide. The CMC material comprises multiple sets of tows woven together to form a preform that is infiltrated with a matrix material. The surface feature is integrally defined at a surface of the cooling passage by an insert member disposed between adjacent tows of at least one of the tow sets. The insert member has a cross-sectional size larger than the adjacent tows, forming a protrusion in the preform that defines the surface feature in the infiltrated, consolidated and cured CMC material.

Abstract: A method of welding articles formed of single-crystal superalloys, particularly single-crystal nickel-base superalloys containing 10 weight percent or more of refractory metals, and welded assemblies formed thereby. A shim is positioned between the articles, and a backing strip is preferably positioned to contact both articles and bridge the gap between the articles. The articles are then welded together using a high energy beam with a low current pulse frequency and low travel speed.

Abstract: An arc welding overlay apparatus that comprises a welding head carriage adapted for movement on a track, an index arm mounted for movement in a direction substantially transverse to the track, a slide mounted for movement in a direction substantially transverse to the index arm, a welding torch mounted to the slide, and means for dispensing a filler material to the welding torch. Feedback means and control means cooperate to indicate and control the movement of the weld head carriage, index arm, electric arc length and the filler dispensing rate. Means are also provided for emergency shutdown of the electric power source.

Abstract: A protective coating and coating method for protecting a thermal barrier coating (TBC) on a component, such as a component of a gas turbine engine. The protective coating comprises alumina particles in a silica-containing matrix, and may be substantially homogeneous or formed of multiple layers having different compositions. The composition and relative amounts of alumina and matrix material in the protective coating enable the coating to react with molten compounds containing calcia, magnesia, alumina and/or silica (CMAS), forming a compound with a melting temperature that is significantly higher than CMAS. As such, infiltration of molten CMAS into the TBC is significantly reduced or entirely avoided.

Abstract: 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 more particularly involves repairing a thermal barrier coating on a component that has suffered localized spallation of the thermal barrier coating. After cleaning the surface area of the component exposed by the localized spallation, a ceramic paste comprising a ceramic powder in a binder is applied to the surface area of the component. The binder is then reacted to yield a ceramic-containing repair coating that covers the surface area of the component and comprises the ceramic powder in a matrix of a material formed when the binder was reacted. The binder is preferably a ceramic precursor material that can be converted immediately to a ceramic or allowed to thermally decompose over time to form a ceramic, such that the repair coating has a ceramic matrix.