Abstract: A coating and coating process for incorporating surface features on an air-cooled substrate surface of a component for the purpose of promoting heat transfer from the component. The coating process generally comprises depositing a first metallic coating material on the surface of the component using a first set of coating conditions to form a first environmental coating layer, and then depositing a second metallic coating material using a second set of coating conditions that differ from the first set, such that an outer environmental coating layer is formed having raised surface features that cause the surface of the outer environmental coating layer to be rougher than the surface of the first environmental coating layer.

Abstract: A beta-phase NiAl overlay coating containing a dispersion of ceramic particles and a process for depositing the overlay coating. If the coating is used to adhere a thermal barrier coating (TBC), the TBC exhibits improved spallation resistance as a result of the dispersion of ceramic particles having a dispersion-strengthening effect on the overlay coating. The overlay coating contains at least one reactive element and is deposited so that the some of the reactive element deposits as the ceramic particles dispersed in the overlay coating.

Abstract: A PVD process and apparatus (120) for depositing a coating (132) from multiple sources (110, 111) of different materials. The process and apparatus (120) are particulaity intended to deposit a beta-nickel aluminide coating (132) containing one or more elements whose vapor pressures are lower than NiAl. The PVD process and apparatus (120) entail feeding at least two materials (110, 111) into a coating chamber (122) and evaporating the materials (110, 111) at different rates from separate molten pools (114, 115) thereof. Articles (130) to be coated are suspended within the coating chamber (122), and transported with a support apparatus (118) relative to the two molten pools (114, 115) so as to deposit a coating (132) with a controlled composition that is a mixture of the first and second materials (110, 111).

Abstract: An article is coasted by preparing a coating source having an aluminum halide, a fluoride or an iodide of a modifying element as a source of the modifying element, and a carrier gas. The modifying element is zirconium, hafnium, and yttrium, or combinations thereof. The coating source is contacted to the article, and the coating source and the article are heated to a coating temperature of at least about 1850° F. for a period of time sufficient to permit aluminum and the modifying element to coat onto the surface of the article. The preferred fluorides of modifying elements are zirconium tetrafluoride and hafnium tetrafluoride.

Abstract: A beta-phase NiAl overlay coating containing a dispersion of ceramic particles and a process for depositing the overlay coating. If the coating is used to adhere a thermal barrier coating (TBC), the TBC exhibits improved spallation resistance as a result of the dispersion of ceramic particles having a dispersion-strengthening effect on the overlay coating. The overlay coating contains at least one reactive element and is deposited so that the some of the reactive element deposits as the ceramic particles dispersed in the overlay coating.

Abstract: The present invention is process for forming diffusion aluminide coatings on an uncoated surface of a substrate, without interdiffusing a sufficient amount of aluminum into a coating layer to adversely affect the coating growth potential and mechanical properties of said coating layer. A metal substrate is provided comprising an external surface and an internal passage therein defined by an internal surface, at least a portion of the external surface of the substrate being coated with a coating layer selected from the group consisting of &bgr;-NiAl-base, MCrAlX, a line-of-sight diffusion aluminide, a non-line-of-sight diffusion aluminide, a pack diffusion aluminide, and a slurry diffusion aluminide on said substrate. The external surface of the substrate is cleaned. The metal substrate is subjected to a aluminum vapor phase deposition process performed using a fluorine-containing activator selected from the group consisting of AiF3, CrF3, NH4F, and combinations thereof, at a rate in the range of about 0.

Abstract: A coating and coating process for incorporating surface features on an air-cooled substrate surface of a component for the purpose of promoting heat transfer from the component. The coating process generally comprises depositing a first metallic coating material on the surface of the component using a first set of coating conditions to form a first environmental coating layer, and then depositing a second metallic coating material using a second set of coating conditions that differ from the first set, such that an outer environmental coating layer is formed having raised surface features that cause the surface of the outer environmental coating layer to be rougher than the surface of the first environmental coating layer.

Abstract: A beta-phase nickel aluminide (NiAl) overlay coating (24) and method for modifying the grain structure of the coating (24) to improve its oxidation resistance. The coating (24) is deposited by a method that produces a grain structure characterized by grain boundaries (44) exposed at the outer coating surface (36). The grain boundaries (44) may also contain precipitates (40) as a result of the alloyed chemistry of the coating (24). During or after deposition, the overlay coating (24) is caused to form new grain boundaries (34) that, though open to the outer surface (36) of the coating (24), are free of precipitates or contain fewer precipitates (40) than the as-deposited grain boundaries (44). New grain boundaries (34) are preferably produced by causing the overlay coating (24) to recrystallize during coating deposition or after deposition as a result of a surface treatment followed by heat treatment.

Abstract: A protective overlay coating for articles used in hostile thermal environments, and particularly for use as a bond coat for a thermal barrier coating deposited on the coating. The coating is predominantly beta-phase NiAl into which a platinum-group metal is incorporated, yielding a coating system capable of exhibiting improved spallation resistance as compared to prior bond coat materials containing platinum, must notably the platinum aluminide diffusion coatings. A preferred composition for the beta-phase NiAl overlay coating further contains chromium and zirconium or hafnium.

Abstract: A method for coating an article includes preparing a coating precursor paint including aluminum-containing pigment particles, a temporary organic binder comprising an acrylic, and a solvent for the temporary organic binder. The coating precursor paint is applied to a surface of the article and thereafter heated to a temperature of from about 1200° F. to about 2100° F. in a non-oxidizing environment.

Abstract: A thermal barrier coating (TBC) (26) for a component (10) intended for use in a hostile environment, such as the superalloy turbine, combustor and augmentor components of a gas turbine engine. The TBC (26) is formed of at least partially stabilized zirconia, preferably yttria-stabilized zirconia (YSZ), and exhibits improved strength and fracture toughness as a result of containing a dispersion of chromia precipitates or particles (32). The TBC (26) preferably consists essentially of YSZ and the chromia particles (32), which are preferably dispersed throughout the microstructure of the TBC (26), including the YSZ grains (30) and grain boundaries. The chromia particles (32) constitute at least 1 to about 10 volume percent of the TBC (26).

Abstract: A multilayer thermal barrier coating (TBC) and method for forming the coating on a component intended for use in a hostile environment. The coating includes layers of particle-free yttria-stabilized zirconia alternating with layers of yttria-stabilized zirconia containing at least three volume percent up to about fifty volume percent of alumina and/or chromia particles and/or precipitates. In the form of particles and/or precipitates in these amounts, sufficient alumina and/or chromia is present to significantly increase the impact and wear resistance of the coating while avoiding discrete and homogeneous layers of alumina and/or chromia and abrupt compositional interfaces that increase the incidence of spallation.

Abstract: A predominantly beta-phase NiAl overlay coating for use as an environmental coating or a TBC bond coat for articles used in hostile thermal environments, such as components of a gas turbine engine. The coating contains up to about 4 atomic percent hafnium, such as in excess of 1.0 atomic percent hafnium. The coating may also contain about 2 to about 15 atomic percent chromium.

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 of at least partially stabilized zirconia, preferably yttria-stabilized zirconia (YSZ), and exhibits improved erosion and impact resistance as a result of containing a dispersion of alumina precipitates or particles. The TBC preferably consists essentially of YSZ and the alumina particles, which are preferably dispersed throughout the microstructure of the TBC, including the YSZ grains and grain boundaries. The alumina particles are present in an amount sufficient to increase the impact and erosion resistance of the TBC, preferably at least 5 volume percent of the TBC.

Abstract: 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.

Abstract: A method for forming a thermal barrier coating system on an article subjected to a hostile thermal environment, such as the hot gas path components of a gas turbine engine. The coating system is generally comprised of a ceramic layer and an environmentally resistant beta phase nickel aluminum intermetallic (&bgr;-NiAl) bond coat that adheres the ceramic layer to the component surface. A thin aluminum oxide scale forms on the surface of the &bgr;-NiAl during heat treatment. An additional layer of diffusion aluminide may can be formed underlying the ceramic layer. The &bgr;-NiAl may contain alloying elements in addition to nickel and aluminum in order to increase the environmental resistance of the &bgr;-NiAl. These elements include hafnium, chromium and zirconium and increase the oxidation resistance of the &bgr;-NiAl. The &bgr;-NiAl is supplied as a powder having a size in the range of 20-80 microns.

Abstract: A method for forming a thermal barrier coating system on an article subjected to a hostile thermal environment, such as the hot gas path components of a gas turbine engine. The coating system is generally comprised of a ceramic layer and an environmentally resistant beta phase nickel aluminum intermetallic (&bgr;-NiAl) bond coat that adheres the ceramic layer to the component surface. A thin aluminum oxide scale forms on the surface of the &bgr;-NiAl during heat treatment. The &bgr;-NiAl may contain alloying elements in addition to nickel and aluminum in order to increase the environmental resistance of the &bgr;-NiAl. The &bgr;-NiAl powder having a size in the range of 20-50 microns is applied using air plasma spray techniques to produce a surface having a roughness of 400 microinches or rougher. The ceramic top coat can be applied using inexpensive thermal spray techniques to greater thicknesses than achievable otherwise because of the rough surface finish of the underlying &bgr;-NiAl bond coat.

Abstract: A method for coating an article includes preparing a coating precursor paint including aluminum-containing pigment particles, a temporary organic binder comprising an acrylic, and a solvent for the temporary organic binder. The coating precursor paint is applied to a surface of the article and thereafter heated to a temperature of from about 1200° F. to about 2100° F. in a non-oxidizing environment.

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 of at least partially stabilized zirconia, preferably yttria-stabilized zirconia (YSZ), and exhibits improved erosion and impact resistance as a result of containing a dispersion of alumina precipitates or particles. The TBC preferably consists essentially of YSZ and the alumina particles, which are preferably dispersed throughout the microstructure of the TBC, including the YSZ grains and grain boundaries. The alumina particles are present in an amount sufficient to increase the impact and erosion resistance of the TBC, preferably at least 5 volume percent of the TBC.

Abstract: A predominantly beta-phase NiAl overlay coating for use as an environmental coating or a TBC bond coat for articles used in hostile thermal environments, such as components of a gas turbine engine. The coating contains up to about 4 atomic percent hafnium, such as in excess of 1.0 atomic percent hafnium. The coating may also contain about 2 to about 15 atomic percent chromium.