Abstract: A coating process and TBC system suitable for protecting the surface of a component subjected to a hostile thermal environment. The TBC system has a first layer with a columnar microstructure, and a second layer on the first layer and with a microstructure characterized by irregular flattened grains. According to one aspect, the first layer is present and the second layer is not present on a first surface portion of the component, and the first and second layers are both present on a second surface portion of the component. According to another aspect, the first and second layers contain the same base ceramic compound.

Abstract: A turbine wall includes opposite back and front sides. Film cooling holes are inclined longitudinally through the wall. Adjacent holes are spaced laterally apart and are inclined oppositely for channeling cooling air therethrough in counterflow.

Abstract: A TBC system suitable for protecting the surface of a substrate subjected to a hostile thermal environment. The TBC system comprises a bond coat on the substrate surface, an alumina scale on the bond coat, and a multilayer TBC comprising a thermal-sprayed first ceramic layer on the alumina scale and a thermal-sprayed second ceramic layer overlying the first ceramic layer. The first ceramic layer consists essentially of partially stabilized zirconia so as to comprise the tetragonal and cubic phases of zirconia. The second ceramic layer consists essentially of fully stabilized zirconia so as to consist essentially of the cubic phase of zirconia. The second ceramic layer is also characterized by having vertical microcracks that extend through the thickness thereof. The second ceramic layer is thicker and more erosion resistant than the first ceramic layer.

Abstract: An article for use in hostile thermal environments, such as a component of a gas turbine engine. The article includes a nickel-base superalloy substrate that is prone to formation of a deleterious secondary reaction zone (SRZ), and an overlay coating having a predominantly gamma prime-phase nickel aluminide (Ni3Al) composition suitable for use as an environmental coating, including a bond coat for a thermal barrier coating. The coating comprises a chromium-containing nickel aluminide intermetallic overlay coating of predominantly the gamma prime phase, in which aluminum is present in the coating in an amount approximately equal to the aluminum content of the superalloy substrate so as to inhibit diffusion of aluminum from the overlay coating into the superalloy substrate.

Abstract: A nickel-base braze material suitable for closing holes in a high temperature component, such as a tip cap hole in a turbine blade. The braze material comprises first and second filler materials and a binder. The first filler material comprises particles of a first alloy, and the second filler material comprises particles of at least a second alloy having a lower melting temperature than the first alloy. The second alloy consists essentially of, by weight, about 8 to about 23 percent chromium, about 4 to about 18 percent cobalt, about 1.5 to about 6.0 percent tantalum, about 1.0 to about 6.0 percent aluminum, about 0.3 to about 1.5 percent boron, about 2.0 to about 6.0 percent silicon, up to 0.2 percent carbon, the balance being nickel and incidental impurities.

Abstract: An overlay coating for articles used in hostile thermal environments. The coating has a predominantly gamma prime-phase nickel aluminide (Ni3Al) composition suitable for use as an environmental coating and as a bond coat for a thermal barrier coating. The coating has a composition of, by weight, at least 6% to about 15% aluminum, about 2% to about 5% chromium, optionally one or more reactive elements in individual or combined amounts of up to 4%, optionally up to 2% silicon, optionally up to 60% of at least one platinum group metal, and the balance essentially nickel. A thermal-insulating ceramic layer may be deposited on the coating.

Abstract: An intermetallic composition suitable for use as an environmentally-protective coating on surfaces of components used in hostile thermal environments, including the turbine, combustor and augmentor sections of a gas turbine engine. The coating contains the gamma-prime (Ni3Al) nickel aluminide intermetallic phase and either the beta (NiAl) nickel aluminide intermetallic phase or the gamma solid solution phase. The coating has an average aluminum content of 14 to 30 atomic percent and an average platinum-group metal content of at least 1 to less than 10 atomic percent, the balance of the coating being nickel, incidental impurities, and optionally hafnium.

Abstract: A coating system and coating method for damping vibration in an airfoil of a rotating component of a turbomachine. The coating system includes a metallic coating on a surface of the airfoil, and a ceramic coating overlying the metallic coating. The metallic coating contains metallic particles dispersed in a matrix having a metallic and/or intermetallic composition. The metallic particles are more ductile than the matrix, and have a composition containing silver and optionally tin. The method involves ion plasma cleaning the surface of the airfoil before depositing the metallic coating and then the ceramic coating.

Abstract: An intermetallic composition suitable for use as an environmentally-protective coating on surfaces of components used in hostile thermal environments, including the turbine, combustor and augmentor sections of a gas turbine engine. The coating contains the gamma-prime (Ni3Al) nickel aluminide intermetallic phase and either the beta (NiAl) nickel aluminide intermetallic phase or the gamma solid solution phase. The coating has an average aluminum content of 14 to 30 atomic percent and an average platinum-group metal content of at least 1 to less than 10 atomic percent, the balance of the coating being nickel, one or more of chromium, silicon, tantalum, and cobalt, optionally one or more of hafnium, yttrium, zirconium, lanthanum, and cerium, and incidental impurities.

Abstract: A process for forming a beta-phase nickel aluminide (NiAl) overlay coating that is suitable for use as a bond coat for a thermal barrier coating (TBC). The overlay coating is deposited by a method that produces a generally columnar grain structure in which grains extend through the coating such that at least some grain boundaries are open at the coating surface. The coating is then peened with a particulate media, followed by heating the overlay coating to a temperature sufficient to cause the overlay coating to recrystallize and form new grain boundaries that are not open to the outer surface of the coating and significantly less susceptible to accelerated oxidation than the original grain boundaries. The particulate media is formed of a composition containing nickel and aluminum, such that an oxide scale that forms on the surface of the coating after the peening operation is substantially free of deleterious oxide compounds, notably iron-containing spinels.

Abstract: A process for refurbishing a worn surface of a shroud support component of a turbomachine, as well as a shroud support component refurbished with the process. The process generally entails removing a surface region of the worn surface so as to define a repair surface on the component. A braze tape formed from a slurry to comprise a braze material and a wear-resistant alloy is then applied to the repair surface, followed by a heat treatment to cause the braze tape to diffusion bond to the repair surface so as to define a built-up surface. The built-up surface is then machined to define a wear-resistant coating on the component.

Abstract: A coating suitable for use as an environmentally-protective coating on surfaces of components used in hostile thermal environments, including the turbine, combustor and augmentor sections of a gas turbine engine. The coating is used in a coating system deposited on a substrate formed of a superalloy material. The coating contacts a surface of the superalloy substrate and is formed of a coating material having a tensile strength of more than 50% of the superalloy material. The coating material is predominantly at least one metal chosen from the group consisting of platinum, rhodium, palladium, and iridium, and has sufficient strength to significantly contribute to the strength of the component on which the coating is deposited.

Abstract: A combustor includes an outer wall and an inner liner joined to an inner shell in turn mounted to an inner casing. The casing includes a first rabbet at an end flange in which is mounted a corresponding flange of the inner shell. The inner shell also includes a second rabbet which receives an end flange of the inner liner. The inner shell is trapped in the first rabbet by an inner retainer. And, the inner liner is trapped in the surrounding second rabbet for aft-mounting the liner and shell to the inner casing.

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: An electron beam physical vapor deposition (EBPVD) process performed with a coating apparatus to produce a coating material (e.g., a ceramic thermal barrier coating) on an article. The EBPVD apparatus generally includes a coating chamber operated at an elevated temperature and a subatmospheric pressure. The coating chamber contains a crucible and a coating material surrounded by and contained within the crucible, and the coating material has a surface exposed by the crucible. The process entails projecting an electron beam onto the surface of the coating material, wherein the electron beam defines a beam pattern having a higher intensity at an interface of the surface of the coating material with the crucible than at a central region of the surface of the coating material.

Abstract: A thermal barrier coating, or TBC, and method for forming the TBC. The TBC is formed of a thermal-insulating material that contains yttria-stabilized zirconia (YSZ) alloyed with at least a third oxide. The TBC 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 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 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 partially stabilized with yttria and to which lanthana, neodymia and/or tantala are alloyed to increase the impact resistance of the coating.

Abstract: A turbine engine shroud segment comprises a body including an outer surface from and along which a segment projection extends away from and in an axial direction. The segment projection includes circumferentially spaced apart segment support surfaces. A shroud hanger comprises a body including an inner surface from and along which a hanger projection extends in an axial direction. The hanger projection includes circumferentially spaced hanger bearing surfaces. In a circumferential turbine engine shroud assembly of shroud segments and hangers, a shroud hanger is assembled between a pair of adjacent shroud segments separated by an axial interface. The hanger projection is in juxtaposition with the interface, and respective segment support surfaces and hanger bearing surfaces are in registry.

Abstract: A method of repairing a turbine blade and the blade repaired thereby. The blade comprises a platform that has become bowed as a result of high temperature creep, with the result that the platform has a concave surface and an oppositely-disposed convex surface. The method generally comprises welding the concave surface to build up a weldment on the concave surface, cooling the weldment during which the weldment shrinks, the convex surface becomes flatter, and the concave surface beneath the weldment becomes flatter, and then removing a surface portion of the weldment so as to create a substantially flat weldment surface overlying the substantially straightened concave surface.

Abstract: A fiber reinforced composite article, comprising a matrix and reinforcing fibers and subjected during operation concurrently to a plurality of temperatures and stresses, varying between a plurality of regions of the article, experiences different stresses concurrently in different regions of the article. The article is provided with fiber reinforcement of a strength in each region greater than the stress experienced in that region. Such fiber reinforcement is provided through a member for inclusion in the matrix, for example in the form of at least one of a fabric, weave, braid, lay-up, etc. One form of such an article for use at relatively high temperatures is a turbine engine component, for example a gas turbine engine exhaust flap. Another form of such an article is a gas turbine engine blading component.