Abstract: A cooling system for cooling of the squealer tip surface region of a high pressure turbine blade used in a gas turbine engine and a method for making a system for cooling of the squealer tip surface region of a high pressure turbine blade used in a gas turbine engine. The method comprises the steps of channeling apertures in a tip cap to a diameter of about 0.004″ to about 0.020″ to allow passage of cooling fluid from a cooling fluid source; applying a bond coat of about 0.0005″ to about 0.010″ in thickness to the tip cap such that the bond coat partially fills the channels; applying a porous TBC layer of at least about 0.003″ in thickness to the bond coat, such that the porous TBC fills the channels; applying a dense ceramic TBC layer over the porous layer; and, passing cooling fluid from a cooling fluid source through the channel into the porous TBC. The density of the dense TBC layer can be varied as needed to achieve desired cooling objectives.

Abstract: A coating is described for use on a superalloy substrate comprising a diffusion barrier as an intermediate layer overlying the substrate and underlying a protective coating having a high aluminum content. The diffusion barrier layer is characterized by having low interdiffusivity for elements from the substrate and the coating, a minimal impact on the mechanical properties of the article which is coated, and can be achieved readily using existing coating application techniques or post heat treat processes. The diffusion barrier layer is preferably an oxide ceramic.

Abstract: At least one airfoil shaped vane made of a low ductility material, for example a ceramic base material such as a ceramic matrix composite or an intermetallic material such as NiAl material, is releasably carried in a turbine vane assembly including inner and outer vane supports by at least one high temperature resistant compliant seal. The seal isolates the vane from at least one of the vane supports and allows independent thermal expansion and contraction of the vane in respect to the support.

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 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 process for creating microgrooves within or adjacent to a TBC layer applied to a gas turbine engine component such as a blade or vane. The process includes the steps of applying a bond coat to the surface of the substrate. A wire mesh is placed a predetermined distance above the bond coat surface. With the wire mesh in position, about 0.002 inches of an inner TBC is applied over the bond coat. The wire in the wire mesh causes a shadow effect as the TBC is applied, so that there are variations in the thickness of the applied TBC, forming micro channels. The wire mesh is removed and an additional outer TBC layer is applied over the inner TBC layer, and the variations in thickness are bridged by the continued deposition of the columnar TBC over the inner TBC layer, forming the microgrooves.

Abstract: A thermal barrier coating (TBC) for a component intended for use in a hostile environment, such as the superalloy turbine, combustor and augmentor components of a gas turbine engine. The TBC is formed to contain small amounts of alumina precipitates dispersed throughout the grain boundaries and pores of the TBC to getter oxide impurities that would otherwise allow or promote grain sintering and coarsening and pore coarsening, the consequence of which would be densification of the TBC and therefore increased thermal conductivity. If sufficiently fine, the precipitates also serve to pin the grains and pore boundaries of the TBC, the effect of which is to reduce the tendency for the microstructure of the TBC to sinter, coarsen and undergo pore redistribution, which also increase thermal conductivity of the TBC 26.

Abstract: A method for transpiration cooling of the flow path surface region of an engine component used in a gas turbine engine by channeling a substrate to provide cooling channels through the substrate having a diameter of about 0.005″ to about 0.02″ to allow passage of cooling fluid from a cooling fluid source through the cooling channels. A bond coat of about 0.0005″ to about 0.005″ in thickness is applied to the substrate such that the bond coat partially fills the cooling channels. A porous TBC of at least about 0.003″ to about 0.01″ thick is applied over the bond coat, such that the TBC completely fills the cooling channels. Cooling fluid from a cooling fluid source is passed through the cooling channels and porous TBC. Because the channel exit is filled with TBC, the cooling fluid is transmitted through the porous passageways of the TBC. The porous passageways provide a plurality of tortuous routes to the TBC surface.

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 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 gas turbine airfoil has an external surface and an internal passage therethrough. The internal passage is selectively coated by providing a source of a flowable precursor coating material in contact with the internal passage of the airfoil, and providing a coating prevention structure overlying at least a portion of the external surface. The flowable precursor coating material is flowed from the source of the flowable precursor coating material and through the internal passage of the airfoil. The coating prevention structure prevents contact of the flowable precursor coating material with the external surface of the airfoil.

Abstract: A gas turbine airfoil has an external surface and an internal passage therethrough. The internal passage is selectively coated by providing a source of a flowable precursor coating material in contact with the internal passage of the airfoil, and providing a coating prevention structure overlying at least a portion of the external surface. The flowable precursor coating material is flowed from the source of the flowable precursor coating material and through the internal passage of the airfoil. The coating prevention structure prevents contact of the flowable precursor coating material with the external surface of the airfoil.

Abstract: A metallic substrate has a substrate surface having a substrate surface of nickel, a substrate aluminum content, and other alloying elements. A maskant is applied overlying the substrate surface to produce a masked substrate surface having an exposed region and a protected region. The maskant includes a plurality of maskant particles, each particle having a maskant particle composition comprising a maskant metal selected from the group of nickel, cobalt, titanium, chromium, iron, and combinations thereof, and a maskant aluminum content. The substrate is aluminided by contacting a source of aluminum to the masked substrate surface, whereby aluminum deposits on the exposed region and does not deposit on the protected region.

Abstract: A coating for use on a superalloy substrate comprising a diffusion barrier as an intermediate layer overlying the substrate and underlying a protective coating having a high aluminum content. The diffusion barrier layer is characterized by having low solubility for aluminum from either the substrate or the protective coating. Further, the diffusion barrier layer has low interdiffusivity for elements from the substrate and the coating, a minimal impact on the mechanical properties of the article which is coated, a minimal thermal expansion mismatch with both the substrate and the high aluminum content protective coating, and can be applied readily using existing coating application techniques. The diffusion barrier is preferably a single phase alloy or intermetallic compound.

Abstract: An environmental overlay coating for articles used in hostile thermal environments, such as turbine, combustor and augmentor components of a gas turbine engine. The overlay coating is predominantly beta-phase NiAl with limited alloying additions of zirconium and chromium. The overlay coating is useful as an environmental coating and as a bond coat that improves the spallation resistance of a thermal barrier coating (TBC) system.

Abstract: A gas turbine airfoil includes an internal cooling passage defined by an internal airfoil surface, and an external airfoil surface. The gas turbine airfoil is protected on both the internal airfoil surface and the external airfoil surface. The internal airfoil surface is protected by forming a diffusion aluminide protective layer at the internal airfoil surface of the internal cooling passage, with substantially no aluminum deposited on the external airfoil surface during the step of forming. The external airfoil surface is protected by depositing an overlay protective coating on the external airfoil surface, with substantially no aluminum or diffusion aluminide between the overlay protective coating and the external airfoil surface. The gas turbine airfoil is operated in a gas turbine engine, and may later be removed for repair.

Abstract: An article is formed of a gas turbine component having a substrate, an internal passage through the substrate defining an internal surface of the substrate, and an internal protective layer overlying the internal surface of the substrate. The internal protective layer has a composition of aluminum, plus, in weight percent, on average from about 0.1 to about 5.0 percent of a modifying element selected from the group consisting of hafnium, yttrium, zirconium, chromium, and silicon, and combinations thereof, and elements found in the substrate.

Abstract: A thermal barrier coating system and a method for forming the coating system on an article. The coating system employs a bond coat of a nickel aluminide alloy over which a thermal-insulating ceramic layer is deposited. The nickel aluminide bond coat contains zirconium, but is otherwise predominantly of the beta (&bgr;) NiAl phase. The bond coat is preferably deposited by a physical vapor deposition process to have a fine-grain microstructure and a limited diffusion zone in the article surface.

Abstract: A superalloy article has a protective layer thereon, either in the form of an environmental coating or a the bond coat for a thermal barrier coating system. The protective layer has a high content of hafnium and/or zirconium to improve the adherence and properties of the protective layer. To introduce the hafnium and/or zirconium into the protective layer, the nickel-base alloy substrate, to which the protective layer is applied, is prepared with an initially elevated content of the hafnium and/or zirconium. A conventional bond coat is applied to the substrate. In an interdiffusion treatment performed during coating and/or subsequently, hafnium and/or zirconium diffuses from the substrate into the bond coat.

Abstract: A coating system (20) for articles used in hostile thermal environments, such as turbine, combustor and augmentor components (10) of a gas turbine engine. The coating system (20) of this invention employs a NiAl-based intermetallic coating (24) containing 30 to 60 atomic percent aluminum so as to be predominantly of the .beta.-NiAl phase, but also contains alloying additions intended to increase the creep strength of the coating (24), and optionally contains alloying additions to getter impurities, increase fracture resistance, and promote oxidation resistance. For this purpose, the coating (24) preferably includes additions of chromium, titanium, tantalum, silicon, hafnium and/or gallium, and optionally contains additions of calcium, zirconium, yttrium, and/or iron.