Abstract: A bond coat and method of forming a bond coat for a thermal barrier coating system are set forth. The bond coat is a roughened bond coat and comprises a layer possessing an uneven, undulated, and irregular surface. The layer is formed of a metal powder mixture disposed on a substrate, such as a turbine component, by high velocity oxygen fuel spraying. The metal powder mixture comprises at least one of a first powder having a first melting point and a second powder having a second melting point that is higher than the first melting point. The bond coat's uneven, undulated, and irregular surface enhances prevention of de-bonding of elements in a thermal barrier coating system.

Abstract: A method of providing a roughened bond coat, for example in a thermal barrier coating system, comprises providing an oxidation-resistant plasma-sprayed layer onto a substrate and disposing a slurry overlayer on the oxidation-resistant plasma-sprayed layer. These steps form a roughened bond coat possessing an uneven, undulated, and irregular surface. A roughened bond coat in a thermal barrier coating system reduces de-bonding of the bond coat and a thermal barrier coating layer, which is desirable to maintain the insulation features of the thermal barrier coating system.

Abstract: A roughened bond coat comprises a screen that includes interwoven wires defining openings and a metallic material disposed on the screen. The screen and metallic material form a roughened bond coat possessing an uneven, undulated, and irregular surface. The metallic material may be one of a slurry and a powder, and applied by coating and spraying, respectively. A thermal barrier coating system, which is formed with and incorporates the roughened bond coat, exhibits greater adhesion of a thermal barrier coating and bond coat due to an increased interfacial surface area provided by the uneven, undulated, and irregular surface.

Abstract: A method of providing a roughened bond coat, for example in a thermal barrier coating system, comprises providing an oxidation-resistant plasma-sprayed layer onto a substrate and disposing a slurry overlayer on the oxidation-resistant plasma-sprayed layer. These steps form a roughened bond coat possessing an uneven, undulated, and irregular surface. A roughened bond coat in a thermal barrier coating system reduces de-bonding of the bond coat and a thermal barrier coating layer, which is desirable to maintain the insulation features of the thermal barrier coating system.

Abstract: A continuously-graded bond coat comprises a gradient of at least one material characteristic value. The gradient extends from a first material characteristic value at a first surface region to a second material characteristic value at a second surface region. The continuously-graded bond coat can be used in a thermal barrier coating system. A source ingot for forming the continuously-graded bond coat comprises aluminum, in an atomic percent range from about 50.0 to less than about 100.0; chromium in an atomic percent range from about 5.0 to about 40.0; silicon in an atomic percent range from about 1.0 to about 17.0; zirconium in an atomic percent range from about a trace to about a 0.5, yttrium in an atomic percent range from a trace to about 2.0; and hafnium in an atomic percent range from about 0.5 to about 2.0. A method for forming the continuously-graded bond coat with the gradient is also provided by the invention.

Abstract: A roughened bond coat comprises a screen that includes interwoven wires defining openings and a metallic material disposed on the screen. The screen and metallic material form a roughened bond coat possessing an uneven, undulated, and irregular surface. The metallic material may be one of a slurry and a powder, and applied by coating and spraying, respectively. A thermal barrier coating system, which is formed with and incorporates the roughened bond coat, exhibits greater adhesion of a thermal barrier coating and bond coat due to an increased interfacial surface area provided by the uneven, undulated, and irregular surface.

Abstract: A method of providing a roughened bond coat, for example in a thermal barrier coating system, comprises providing an oxidation-resistant plasma-sprayed layer onto a substrate and disposing a slurry overlayer on the oxidation-resistant plasma-sprayed layer. These steps form a roughened bond coat possessing an uneven, undulated, and irregular surface. A roughened bond coat in a thermal barrier coating system reduces de-bonding of the bond coat and a thermal barrier coating layer, which is desirable to maintain the insulation features of the thermal barrier coating system.

Abstract: A composition comprises cobalt; chromium; carbon; boron; zirconium; aluminum; at least one refractory material; and nickel. The composition is used as a repair material for repairing superalloy articles in a repair process.

Abstract: A method for forming an exterior surface of a high-temperature component, such as a blade or vane of a gas turbine engine. The method entails forming a shell by a powder metallurgy technique that yields an airfoil whose composition can be readily tailored for the particular service conditions of the component. The method generally entails providing a pair of inner and outer mold members that form a cavity therebetween. One or more powders and any desired reinforcement material are then placed in the cavity and then consolidated at an elevated temperature and pressure in a non-oxidizing atmosphere. Thereafter, at least the outer mold member is removed to expose the consolidated powder structure. By appropriately shaping the mold members to tailor the shape of the cavity, the consolidated powder structure has the desired shape for the exterior shell of a component, such that subsequent processing of the component does not require substantially altering the configuration of the exterior shell.

Abstract: A bond coat and method of forming a bond coat for a thermal barrier coating system are set forth. The bond coat is a roughened bond coat and comprises a layer possessing an uneven, undulated, and irregular surface. The layer is formed of a metal powder mixture disposed on a substrate, such as a turbine component, by high velocity oxygen fuel spraying. The metal powder mixture comprises at least one of a first powder having a first melting point and a second powder having a second melting point that is higher than the first melting point. The bond coat's uneven, undulated, and irregular surface enhances prevention of de-bonding of elements in a thermal barrier coating system.

Abstract: A bond coat (20) of a thermal barrier coating system for components designed for use in a hostile thermal environment, such as turbine, combustor and augmentor components of a gas turbine engine. The composition of the bond coat (20) has graded thermal expansion properties that moderate the transition between a metal substrate (10) and a thermal-insulating ceramic layer (12) of a TBC protecting the substrate (10), while also reducing the service temperature of the bond coat (20) so as to reduce its rate of oxidation. Preferably, the bond coat (20) has multiple layers (20a, 20b, 20c), with the coefficients of thermal conductivity of the individual bond coat layers (20a, 20b, 20c) being very close to that of the substrate (10) in order to promote heat transfer from the outward layer (20c) of the bond coat (20) to the substrate (10).

Abstract: A method for forming an exterior surface of a high-temperature component, such as a blade or vane of a gas turbine engine. The method entails forming a shell by a powder metallurgy technique that yields an airfoil whose composition can be readily tailored for the particular service conditions of the component. The method generally entails providing a pair of inner and outer mold members that form a cavity therebetween. One or more powders and any desired reinforcement material are then placed in the cavity and then consolidated at an elevated temperature and pressure in a non-oxidizing atmosphere. Thereafter, at least the outer mold member is removed to expose the consolidated powder structure. By appropriately shaping the mold members to tailor the shape of the cavity, the consolidated powder structure has the desired shape for the exterior shell of a component, such that subsequent processing of the component does not require substantially altering the configuration of the exterior shell.

Abstract: Methods of making gas turbine structures with cooling channels, such as, for example, combustor/transition pieces for gas turbines having a double wall with a plurality of cooling channels, having axially and/or circumferential cross-flow passages positioned between the structure's inner member and the outer member to provide cooling air thereto, are disclosed.

Abstract: A bond coat of a thermal barrier coating system for components designed for use in a hostile thermal environment, such as turbine, combustor and augmentor components of a gas turbine engine. The composition of the bond coat has graded thermal expansion properties that moderate the transition between a metal substrate and a thermal-insulating ceramic layer of a TBC protecting the substrate, while also reducing the service temperature of the bond coat so as to reduce its rate of oxidation. Preferably, the bond coat has multiple layers, with the coefficients of thermal conductivity of the individual bond coat layers being very close to that of the substrate in order to promote heat transfer from the outward layer of the bond coat to the substrate. By minimizing the service temperature of the bond coat while grading the thermal expansion properties through the coating system, a more spall-resistant coating system is achieved.

Abstract: Methods of making cylindrical structures with cooling channels, such as, for example, combustor/transition pieces for gas turbines having a double wall with a plurality of cooling channels, both axially and, in some cases, circumferential cross-flow passages positioned between the structure's inner member and the outer member to provide cooling air thereto, are disclosed. The cooling channels are formed in the area between the inner member of the structure and the outer member thereof. The passages preferably extend both axially and circumferentially with respect to the direction of flow through the structure. The axial passages extend completely from one end to the other and the circumferential passages extend around the circumference of the structure.

Abstract: An extension is formed directly on an article by casting a compatible material into a ceramic mold that is attached on an end of the article, followed by cooling of the end under controlled conditions sufficient to cause an integral extension to solidify on the article. A ceramic mold is utilized over the end of the article, with a mold cavity that generally defines the shape of the extension to be formed. The mold may be formed in situ on the mandrel, or preformed and attached to the subject article over the mandrel. Extensions formed by the method of this invention have a microstructure that is continuous and compatible with that of the article. Such microstructures may include epitaxial growth of the extension from the microstructure of the article. The method establishes a temperature gradient within the article during solidification that may be further controlled by auxiliary heating and/or cooling of the article and/or extension during the practice of the method.

Abstract: A combustor/transition piece for a gas turbine including a double walled structure having a plurality of cooling channels, both axially and, in some cases, circumferential cross-flow passages positioned between the structure's inner member and the outer member to provide cooling air thereto, are formed in the area between the inner member of the combustor and the outer member thereof. The passages preferably extend both axially and circumferentially with respect to the direction of flow through the combustor/transition piece. The axial passages extend completely from one end to the other and the circumferential passages extend around the circumference of the combustor/transition piece. The addition of a circumferential cross-flow passage connecting axial flow coolant passages in double wall turbine components can prevent combustor/transition piece part failure due to axial passage inlet blockage without affecting normal, unblocked cooling.

Abstract: Si-Fe-Cr base coating alloys that significantly promote the oxidation resistance of niobium-base alloys and intermetallic materials when deposited and reaction bonded to the niobium-base material. The coating alloys are deposited and then reaction bonded to a niobium-base material to yield an oxidation-resistant coating comprising an interaction layer containing at least one oxidation-resistant Si-Fe-Nb-Cr intermetallic phase.

Abstract: An extension is formed directly on an article by dipping a portion or end of the article having an attached integral mandrel into a molten bath of a compatible alloy, followed by withdrawal of the end under controlled conditions sufficient to cause an integral extension to solidify on the article. A ceramic mold is utilized over the dipped end of the article and the integral mandrel with a mold cavity that generally defines the shape of the extension to be formed. The mold may be formed in situ on the mandrel, or preformed and attached to the subject article over the mandrel. The integral mandrel is melted within the mold by dipping the mandrel into the molten alloy. The mandrel acts as a buffer between the molten material and the article while permitting melting of the article end and solidification of the integral extension. Extensions formed by the method of this invention have a microstructure that is continuous and compatible with that of the article.

Abstract: An extension is formed directly on an article by melting a portion or end of the article having an attached integral mandrel within a ceramic mold, followed by cooling of the end under controlled conditions sufficient to cause an integral extension to solidify on the article. A ceramic mold is attached on the end of the article over the integral mandrel with a mold cavity that generally defines the shape of the extension to be formed. The mold may be formed in situ on the mandrel, or preformed and attached to the subject article over the mandrel. Extensions formed by the method of this invention have a microstructure that is continuous and compatible with that of the article. Such microstructures may include epitaxial growth of the extension from the microstructure of the article. The method establishes a temperature gradient within the article during solidification that may be further controlled by auxiliary heating and/or cooling of the article and/or extension during the practice of the method.