Abstract: A turbine engine axial series of members, axially distinct at least radially outwardly, enables independent axial movement to close gaps therebetween, eliminating need for fluid seals. During engine operation, an axially forward first member surface is movable an axial movement distance to close any gap between the first member and a second member that floats axially independently of adjacent members and that is movable axially responsive to axial force from the first member. Axial movement of the second member toward a third member closes any gap therebetween, the axial length of the gap, prior to engine operation, being substantially no greater than the axial movement distance of the first member.

Abstract: A thermal barrier coating, or TBC (26), and method for forming the TBC (26). The TBC (26) is formed of a thermal-insulating material that contains yttria-stabilized zirconia (YSZ) alloyed with at least a third oxide. The TBC (26) is formed to also contain elemental carbon, and may potentially contain carbides and/or a carbon-containing gas that forms from the thermal decomposition of carbon. The TBC (26) is characterized by lower density and thermal conductivity, high temperature stability and improved mechanical properties. To exhibit the desired effect, the third oxide is more particularly one that increases the lattice strain energy of the TBC microstructure as a result of having an ion size that is sufficiently different than a zirconium ion.

Abstract: A turbine engine shroud segment having a body including a circumferentially arcuate radially inner surface defining a circumferential arc and a radially outer surface is provided, at least at one axially spaced apart outer surface edge portion surface, with a surface depression extending circumferentially across the outer edge portion and including a planar seal surface. The planar seal surface is spaced apart radially outwardly from the circumferential arc defining a spaced apart chord of the arc. The planar seal surface is joined with the segment body radially outer surface through an arcuate transition surface. In a circumferential assembly of a plurality of the shroud segments into a turbine engine shroud assembly, at least one of the outer surface edge portions and its respective depression portion and fluid seal surface is distinct axially from an axially juxtaposed engine member by a separation therebetween.

Abstract: A method is provided for refurbishing a service operated metallic coating on a substrate alloy, the coating including at least within a coating outer surface at least one oxide chemically grown from at least one coating element, for example Al, and chemically bonded with the coating outer surface as a result of thermal exposure during service operation. Growth of the oxide has depleted at least a portion of the coating element from the coating. The method comprises removing the oxide from the coating outer surface while substantially retaining the metallic coating, thereby exposing in the coating outer surface at least one surface void that had been occupied by the oxide. The retained metallic coating is mechanically worked, substantially without removal of the retained coating, to close the void, providing a treated metallic coating surface over which a refurbishing coating is applied.

Abstract: A process of depositing a coating system suitable for use as an environmental barrier coating on various substrate materials, particularly those containing silicon and intended for high temperature applications such as the hostile thermal environment of a gas turbine engine. The process comprises depositing a first coating layer containing mullite, and preferably a second coating layer of an alkaline earth aluminosilicate, such as barium-strontium-aluminosilicate (BSAS), by thermal spraying while maintaining the substrate at a temperature of 800° C. or less, preferably 500° C. or less, by which a substantially crack-free coating system is produced with desirable mechanical integrity.

Abstract: A multiple impingement cooled structure is provided having two or more stages of impingement cooling wherein the stages are arranged so as to have substantially constant cooling effectiveness.

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 engine component includes a perforate metal wall having pores extending therethrough. The wall has a first surface covered by a thermal barrier coating. The pores have first ends which are covered by the thermal barrier coating, and the pores are ventilated from an opposite second surface of the wall for cooling the thermal barrier coating.

Abstract: A method of removing a ceramic coating, such as a thermal barrier coating (TBC) of yttria-stabilized zirconia (YSZ), from the surface of a component, such as a gas turbine engine component. The method generally entails subjecting the ceramic coating to an aqueous solution of ammonium bifluoride, optionally containing a wetting agent, such as by immersing the component in the solution while maintained at an elevated temperature. Using the method of the invention, a ceramic coating can be completely removed from the component and any cooling holes, with essentially no degradation of the bond coat.

Abstract: A turbine engine shroud segment comprises a body including a radially outer surface having axially and circumferentially spaced apart edge surfaces. The segment includes a projection integral with and projecting generally radially outwardly from the body, and positioned at a generally midway surface portion between the axially spaced apart edge surfaces. The projection comprises a head and a transition portion with a cross section smaller than that of the head and integral with and between the head and the body. In a turbine engine shroud assembly, a plurality of such shroud segments are assembled circumferentially with a shroud hanger carrying the projection in a hanger cavity through end portions of radially inner opposed hook members that register with the projection at the transition portion.

Abstract: A thermal barrier coating (TBC) system and method for forming the coating system on a component. The method generally entails forming a TBC on the surface of the component so that the TBC has at least an outer portion that is resistant to infiltration by CMAS. The TBC is formed by co-depositing first and second ceramic compositions by physical vapor deposition so that the entire TBC has columnar grains and at least the outer portion of the TBC is a mixture of the first and second ceramic compositions. The outer portion is preferably a continuation of the inner portion, such that the TBC is not characterized by discrete inner and outer coatings. The second ceramic composition serves to increase the resistance of the outer portion of the TBC to infiltration by molten CMAS. A platinum-group metal may be co-deposited with the first and second ceramic compositions, or deposited before the TBC and then diffused into the outer portion as a result of the parameters employed in the deposition process.

Abstract: An apparatus (10) and method for removing an abradable material from an interior surface (16) of a fan containment case (14), without requiring removal of the fan containment case (14) from its engine (12). The apparatus (10) and method generally involve adjusting the elevation of a blast head (40) and centering a horizontal axis of rotation thereof with the fan containment case (14) to position the blast head (40) adjacent the abradable material on the case surface (16). An erosion media is then sprayed with the blast head (40) in a substantially radial direction relative to the horizontal axis of rotation of the blast head (40), such that the erosion media impacts and erodes the abradable material. The blast head (40) is rotated about the horizontal axis of rotation thereof so that the erosion media is sprayed at the abradable material along the entire circumference of the fan containment case (14).

Abstract: A coating composition (24) for a thermal/environmental barrier coating (T/EBC) system (14) particularly suited for protecting silicon-containing substrates (12), such as articles exposed to high temperatures including the hostile thermal environment of a gas turbine engine. The coating composition (24) is an alkaline earth aluminate or an alkaline earth aluminosilicate containing, by molar percent, about 20% to about 40% barium oxide, about 9% to about 20% strontia, about 19% to about 50% alumina, and optionally up to about 40% silica, wherein barium oxide and strontia are present in a combined amount of about 37 to about 50 molar percent of the coating composition (24). The T/EBC system (14) may include one or more intermediate layers (16,20,22) that adhere the coating composition (24) to the silicon-containing surface (12). The T/EBC system (14) may further include an outermost coating (18) of stabilized zirconia or another high-temperature ceramic material.

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 coating material, particularly a thermal barrier coating, 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 coating material is zirconia that is stabilized with yttria and to which an oxide additive of niobia or titania is alloyed to reduce and stabilize the thermal conductivity of the coating.

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 process of removing deposits from through-holes in a component, such as metallic bond coat and ceramic materials from cooling holes in an air-cooled gas turbine engine. The process is particularly effective in removing a TBC material deposited in a cooling hole of a component as a result of depositing a coating of the TBC material on a surface of the component, in which the deposit is removed from the cooling hole without damaging the cooling hole or the TBC coating surrounding the cooling hole on the coated surface of the component. A preferred feature is that the cooling hole, including the entrance to the hole at a surface of the component opposite the coated surface and the coating surrounding the exit of the hole at the coated surface, exhibits improved surface characteristics that increase the discharge coefficient of the cooling hole, as evidenced by an increase in the effective area of the cooling hole.

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 coated article is prepared by furnishing an article substrate having a free sulfur content of less than about 1 part per million. The low-sulfur article may be made of a material selected to have a low sulfur content, provided with a scavenging element that reacts with free sulfur to produce a sulfur compound, or desulfurized by contact with a reducing gas such as hydrogen. A platinum-group metal layer is deposited over the article substrate, and a ceramic coating is applied over the platinum-group metal layer.

Abstract: A combustor liner is provided having first and second annular bands which define an overlapping circumferential joint area, wherein a weld is disposed in the joint area encompassing substantially all of the axial length of the joint area. A method for producing such a combustor liner is also provided.