Abstract: A thermal barrier coating and deposition process for a component intended for use in a hostile thermal environment, such as the turbine, combustor and augmentor components of a gas turbine engine. The TBC has a first coating portion on at least a first surface portion of the component. The first coating portion is formed of a ceramic material to have at least an inner region, at least an outer region overlying the inner region, and a columnar microstructure whereby the inner and outer regions comprise columns of the ceramic material. The columns of the inner region are more closely spaced than the columns of the outer region so that the inner region of the first coating portion is denser than the outer region of the first coating portion, wherein the higher density of the inner region promotes the impact resistance of the first coating portion.

Abstract: Thermal barrier coating (TBC) and a method of depositing a TBC having a modulated columnar microstructure that exhibits increased impact resistance. The TBC is deposited to have a columnar microstructure in which columns extend from a substrate surface. The columns having inner regions contacting the surface, outer regions near an outermost surface of the TBC, and interior regions therebetween. The inner regions of the columns are substantially normal to the substrate surface and at least one of the interior and outer regions of the columns are nonaligned with its respective inner regions, so that the columns of the columnar microstructure are continuous but modulated between the inner and outer regions to reduce tensile stresses within the columns resulting from particle impact.

Abstract: A method of operating an EBPVD apparatus (10) to deposit a ceramic coating on an article (20), such that the thermal conductivity of the coating is both minimized and stabilized. More particularly, the EBPVD apparatus (10) is operated to perform multiple successive coating operations which together constitute a coating campaign. During the campaign, the surface temperatures of the articles (20) being coated do not exceed about 1000° C. as a result of the combined heat transfer from the coating chamber (14) to the articles (20) being reduced during the course of the campaign, even though the temperature within the coating chamber (14) continuously rises during successive coating operations of the campaign. Ceramic coatings deposited at such relatively low temperatures exhibit lower and more stable thermal conductivities.

Abstract: A gas turbine component article has an airfoil section and is formed of a nickel-base superalloy. An unmasked region of the airfoil section has a platinum aluminide protective coating, and a masked region of the airfoil section has an aluminide coating. The platinum aluminide preferably is deposited at a trailing edge of the airfoil section that is susceptible to low-cycle fatigue damage when a platinum aluminide coating is present.

Abstract: A method of operating an EBPVD apparatus (10) to deposit a ceramic coating on an article (20), such that the thermal conductivity of the coating is both minimized and stabilized. More particularly, the EBPVD apparatus (10) is operated to perform multiple successive coating operations which together constitute a coating campaign. During the campaign, the surface temperatures of the articles (20) being coated do not exceed about 1000° C. as a result of the combined heat transfer from the coating chamber (14) to the articles (20) being reduced during the course of the campaign, even though the temperature within the coating chamber (14) continuously rises during successive coating operations of the campaign. Ceramic coatings deposited at such relatively low temperatures exhibit lower and more stable thermal conductivities.

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 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.

Abstract: A method is provided for making, from a plurality of members brazed together, an article including an environmental resistant surface coating and a wear resistant surface portion. Prior to brazing, the members are assembled with at least one preform including the wear resistant material in a matrix including a first brazing alloy having a brazing temperature in a brazing temperature range. The assembly of members includes a second brazing alloy having a brazing temperature in the brazing temperature range. The assembly of members and wear resistant preform is heated in the brazing temperature range to provide a brazed article preform. Then the article preform is machined to a selected geometry and can be coated with the environmental coating.

Abstract: A thermal barrier coating (TBC) system and method for forming the TBC system on a component designed for use in a hostile thermal environment, such as superalloy turbine, combustor and augmentor components of a gas turbine engine. The TBC system exhibits improved spallation resistance as a result of having a bond coat formed to contain a dispersion of oxide particles in its outer surface region. A method for preferentially entrapping oxide particles in a bond coat entails depositing the oxide particles on the surface of the component prior to forming the bond coat, which may be a diffusion aluminide or an aluminized overlay coating. Deposition of the bond coat causes the oxide particles to become dispersed in the outer surface region of the bond coat. A particular feature of this invention is the ability to preferentially entrap oxides of elements that are not present in the bond coat or a substrate region of the component on which the bond coat is formed.

Abstract: A gas turbine component article has an airfoil section and is formed of a nickel-base superalloy. An unmasked region of the airfoil section has a platinum aluminide protective coating, and a masked region of the airfoil section has an aluminide coating. The platinum aluminide preferably is deposited at a trailing edge of the airfoil section that is susceptible to low-cycle fatigue damage when a platinum aluminide coating is present.

Abstract: A gas turbine component article has an airfoil section and is formed of a nickel-base superalloy. An unmasked region of the airfoil section has a platinum aluminide protective coating, and a masked region of the airfoil section has an aluminide coating. The platinum aluminide preferably is deposited at a trailing edge of the airfoil section that is susceptible to low-cycle fatigue damage when a platinum aluminide coating is present.

Abstract: An article comprising an airfoil surface is provided with a thermal insulating outer layer on at least one region, but not all, of the airfoil surface. The region is selected from the airfoil surface which has been observed to experience more strenuous environmental operating conditions during service operation than the airfoil surface outside of the region. In one form, the thermal insulating outer layer is applied to at least one region of each of a plurality of airfoil surfaces. Each airfoil surface is disposed about an axis of rotation with the region of each airfoil surface facing generally outwardly from the axis of rotation and from each other. The airfoil surfaces are rotated about the axis of rotation while a thermal insulating material contacts at least the regions.

Abstract: A tip cap hole is loaded with a first composition comprising particles of a first alloy having a solidus temperature above the brazing temperature. The first composition is covered with a second composition comprising particles of a second alloy having a liquidus temperature below the brazing temperature. The second composition is heated to the brazing temperature to cause particles of the second alloy to melt to form a liquid of the second alloy which is carried into spaces between the particles of the first alloy by capillarity. The liquid of the second alloy is cooled to form a solid securely bonding the particles of the first alloy. By weight, the second alloy has no more than 1% B and from 3% to 11% Si. The first alloy has Cr and at least about 5% Al, at least about 0.5% Hf, no more than 0.5% Ti.

Abstract: A curved component such as a turbine airfoil, shroud, or combustor centerbody is prepared with a platinum or a platinum-aluminide protective coating over only a portion of the surface thereof. The coating may serve as an environmental coating, or as a bond coat of a thermal barrier coating system. The partial coverage is achieved by depositing platinum only over a portion of the surface of the component, typically including the concave portion in the case of an airfoil, optionally depositing an aluminum layer, and optionally interdiffusing the platinum and aluminum layers.

Abstract: A tip cap hole is loaded with a first composition comprising particles of a first alloy having a solidus temperature above the brazing temperature. The first composition is covered with a second composition comprising particles of a second alloy having a liquidus temperature below the brazing temperature. The second composition is heated to the brazing temperature to cause particles of the second alloy to melt to form a liquid of the second alloy which is carried into spaces between the particles of the first alloy by capillarity. The liquid of the second alloy is cooled to form a solid securely bonding the particles of the first alloy. By weight, the second alloy has no more than 1% B and from 3% to 11% Si. The first alloy has Cr and at least about 5% Al, at least about 0.5% Hf, no more than 0.5% Ti.

Abstract: An article comprising an airfoil surface is provided with a thermal insulating outer layer on at least one region, but not all, of the airfoil surface. The region is selected from the airfoil surface which has been observed to experience more strenuous environmental operating conditions during service operation than the airfoil surface outside of the region. In one form, the thermal insulating outer layer is applied to at least one region of each of a plurality of airfoil surfaces. Each airfoil surface is disposed about an axis of rotation with the region of each airfoil surface facing generally outwardly from the axis of rotation and from each other. The airfoil surfaces are rotated about the axis of rotation while a thermal insulating material contacts at least the regions.