Patents by Inventor Ramgopal Darolia
Ramgopal Darolia has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7189459Abstract: One exemplary embodiment of a turbine component (which may be a blade) comprises a substrate comprising a silicide-based material, a plurality of through holes disposed in the substrate, the holes being configured to receive an airflow, a silicide coating disposed at the surfaces of the substrate and the through holes, and a thermal barrier coating disposed at the silicide coating. In another exemplary embodiment the silicide coating may be replaced by a Laves phase-containing layer. In still another exemplary embodiment the silicide coating may be replaced by a diffusion barrier layer disposed at a surface of the substrate and a platinum group metal layer disposed at the diffusion barrier layer. One exemplary embodiment of a blade may comprise an airfoil comprising a silicide-based material and through holes disposed therein, a cooling plenum disposed in the airfoil, and a base configured to receive the airfoil in a dovetail fit, the base comprising a superalloy.Type: GrantFiled: December 31, 2002Date of Patent: March 13, 2007Assignee: General Electric CompanyInventors: Melvin Jackson, Pazhayannur Subramanian, Ji-Cheng Zhao, Bernard Bewlay, Ramgopal Darolia, Robert Schafrik
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Patent number: 7186091Abstract: A method of cooling a gas turbine engine component having a perforate metal wall includes providing a plurality of pores in the wall, wherein the pores extend substantially perpendicularly through the wall, and wherein the pores are covered and sealed closed at first ends thereof by a thermal barrier coating disposed over a first surface of the wall, and providing a plurality of film cooling holes in the wall, wherein the holes extend substantially perpendicularly through the wall and the thermal barrier coating. The method also includes providing cooling fluid to the plurality of pores and the plurality of film cooling holes along a second surface of the wall, channeling the cooling fluid through the pores for back side cooling an inner surface of the thermal barrier coating, and channeling the cooling fluid through the holes for film cooling an outer surface of the thermal barrier coating.Type: GrantFiled: November 9, 2004Date of Patent: March 6, 2007Assignee: General Electric CompanyInventors: Ching-Pang Lee, Ronald Scott Bunker, Harvey Michael Maclin, Ramgopal Darolia
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Publication number: 20070044869Abstract: A nickel-base alloy that exhibits a desirable balance of mechanical properties, environmental properties, and microstructural stability suitable for gas turbine engine applications. The nickel-base alloy is in the form of a single-crystal casting consisting of, by weight, 5.75% to 6.5% aluminum, 4% to 5% tantalum, 2% to 6% chromium, 5.5% to 7% tungsten, 1.5% to 3% molybdenum, 4% to 5% rhenium, up to 1.0% niobium, 10% to 16% cobalt, up to 1% titanium, 0.01% to 0.05% carbon, up to 0.005% boron, up to 0.01% yttrium, 0.5% to 1.0% hafnium, the balance nickel and incidental impurities. The alloy has a density of not more than 0.320 lbs/in3 (about 8.87 g/cm3), and contains a combined amount of aluminum, tungsten, molybdenum, niobium, titanium, and hafnium specified relative to the combined amount of tantalum and rhenium.Type: ApplicationFiled: September 1, 2005Publication date: March 1, 2007Applicant: GENERAL ELECTRIC COMPANYInventors: Ramgopal Darolia, William Walston, Kevin O'Hara
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Patent number: 7172820Abstract: A strengthened bond coat for improving the adherence of a thermal barrier coating to an underlying metal substrate to resist spallation without degrading oxidation resistance of the bond coat. The bond coat comprises a bond coating material selected from the group consisting of overlay alloy coating materials, aluminide diffusion coating materials and combinations thereof. Particles comprising a substantially insoluble bond coat strengthening compound and having a relatively fine particle size of about 2 microns or less are dispersed within at least the upper portion of the bond coat in an amount sufficient to impart strengthening to the bond coat, and thus limit ratcheting or rumpling thereof.Type: GrantFiled: October 13, 2005Date of Patent: February 6, 2007Assignee: General Electric CompanyInventors: Ramgopal Darolia, Joseph David Rigney, Gillion Herman Marijnissen, Eric Richard Irma Carolus Vergeldt, Annejan Bernard Kloosterman
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Publication number: 20070020399Abstract: A turbine engine component comprising a substrate made of a nickel-base or cobalt-base superalloy, a non-metallic oxide or nitride diffusion barrier layer overlying the substrate, and a protective coating overlying the barrier layer, the protective coating comprising at least one platinum group metal selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium. The diffusion barrier layer may be a deposited or thermally grown oxide material, especially aluminum oxide. The protective coating may be heat treated to increase homogeneity of the coating and adherence with the substrate. The component typically further comprises a ceramic thermal barrier coating overlying the protective coating. Also disclosed are methods for forming a protective coating system on the turbine engine component by forming the non-metallic oxide or nitride diffusion barrier layer on the substrate and then depositing the platinum group metal on top of the barrier layer.Type: ApplicationFiled: June 28, 2005Publication date: January 25, 2007Inventors: Mark Gorman, Bangalore Nagaraj, Ramgopal Darolia
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Patent number: 7150922Abstract: 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.Type: GrantFiled: December 13, 2002Date of Patent: December 19, 2006Assignee: General Electric CompanyInventors: Irene Spitsberg, Joseph David Rigney, Ramgopal Darolia, Elissa Hae-Kyung Lee, Jeffrey Allan Pfaendtner
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Publication number: 20060216534Abstract: Zirconia-containing ceramic compositions that are capable of providing thermal barrier coatings wherein the zirconia is stabilized in the cubic crystalline phase. These compositions comprise at least about 50 mole % zirconia and a stabilizing amount up to about 49 mole % of a stabilizer component comprising: (1) a first metal oxide selected from the group consisting of ytterbia, neodymia, mixtures of ytterbia and neodymia, mixtures of ytterbia and lanthana, mixtures of neodymia and lanthana, and mixtures of ytterbia, neodymia and lanthana in an amount of from about 5 to about 49 mole % of the composition; and (2) a second metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india and mixtures thereof in an amount of about 4 mole % or less of the composition. The ceramic composition further comprises one or more of a third metal oxide selected from the group consisting of: (a) hafnia in an amount from about 0.Type: ApplicationFiled: November 29, 2005Publication date: September 28, 2006Inventors: Brett Boutwell, Mark Gorman, Irene Spitsberg, Ramgopal Darolia, Robert Bruce, Venkat Venkataramani
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Patent number: 7094444Abstract: According to an embodiment of the invention, a method for repairing a coated high pressure turbine blade, which has been exposed to engine operation, to restore coated airfoil contour dimensions of the blade, and improve upon the prior bond coat is disclosed. The method comprises providing an engine run high pressure turbine blade including a base metal substrate made of a nickel-based alloy and having thereon a thermal barrier coating system. The thermal barrier coating system comprises a diffusion bond coat on the base metal substrate and a top ceramic thermal barrier coating comprising a yttria stabilized zirconia material. The top ceramic thermal barrier coating has a nominal thickness t. The method further comprises removing the thermal barrier coating system, wherein a portion of the base metal substrate also is removed, and determining the thickness of the base metal substrate removed. The portion of the base metal substrate removed has a thickness, ?t.Type: GrantFiled: November 13, 2003Date of Patent: August 22, 2006Assignee: General Electric CompanyInventors: Joseph D. Rigney, Ching-Pang Lee, Ramgopal Darolia
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Publication number: 20060182892Abstract: 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.Type: ApplicationFiled: December 13, 2002Publication date: August 17, 2006Applicant: GENERAL ELECTRIC COMPANYInventors: Irene Spitsberg, Joseph Rigney, Ramgopal Darolia, Elissa Lee, Jeffrey Pfaendtner
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Patent number: 7087266Abstract: 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.Type: GrantFiled: June 18, 2004Date of Patent: August 8, 2006Assignee: General Electric CompanyInventors: Ramgopal Darolia, Boris A. Movchan, Yuriy E. Rudoy, Leonella M. Nerodenko, Irene Spitsberg, David John Wortman
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Patent number: 7078073Abstract: According to an embodiment of the invention, a method for repairing a coated high pressure turbine blade, which has been exposed to engine operation, to restore coated airfoil contour dimensions of the blade, is disclosed. The method comprises providing an engine run high pressure turbine blade including a base metal substrate made of a nickel-based alloy and having thereon a thermal barrier coating system. The thermal barrier coating system comprises a diffusion bond coat on the base metal substrate and a top ceramic thermal barrier coating comprising a yttria stabilized zirconia material. The top ceramic thermal barrier coating has a nominal thickness t. The method further comprises removing the thermal barrier coating system, wherein a portion of the base metal substrate also is removed, and determining the thickness of the base metal substrate removed. The portion of the base metal substrate removed has a thickness, ?t.Type: GrantFiled: November 13, 2003Date of Patent: July 18, 2006Assignee: General Electric CompanyInventors: Joseph D. Rigney, Ching-Pang Lee, Ramgopal Darolia
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Patent number: 7070866Abstract: In one embodiment of the invention, a NiAl overlay bond coating composition comprises a NiAl alloy. The alloy comprises Zr and at least one modifying element in an amount effective to form a stabilized oxide structure comprising stabilized zirconia including a substantially tetragonal structure upon oxidation of the alloy. The tetragonal structure is stabilized such that it does not change phases and revert to a monoclinic or monoclinic and tetragonal structure, which is not substantially tetragonal, upon thermal cycling.Type: GrantFiled: May 27, 2004Date of Patent: July 4, 2006Assignee: General Electric CompanyInventors: Joseph D. Rigney, David R. Clarke, Ramgopal Darolia
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Publication number: 20060121293Abstract: In accordance with an embodiment of the invention, an article is provided. The article comprises a substrate comprised of silicon containing material, an environmental barrier coating (EBC) overlying the substrate and a thermal barrier coating (TBC) on the environmental barrier coating. The thermal barrier coating comprising a compound having a rhombohedral phase.Type: ApplicationFiled: December 6, 2004Publication date: June 8, 2006Inventors: Brett Boutwell, Irene Spitsberg, Christine Govern, Bangalore Nagaraj, Brian Hazel, Ramgopal Darolia, Curtis Johnson, Yan Gao, Mark Gorman
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Publication number: 20060121294Abstract: In accordance with an embodiment of the invention, a thermal barrier coating for inclusion in a thermal barrier coating system is provided. The thermal barrier coating comprises a compound having a rhombohedral phase. In accordance with another embodiment of the invention, a thermal barrier coating is provided that comprises a compound having the formula of: A4B3O12, wherein A is at least one rare earth element; and B is selected from the group consisting of Zr, Hf and mixtures thereof.Type: ApplicationFiled: December 6, 2004Publication date: June 8, 2006Inventors: Brett Allen Boutwell, Ramgopal Darolia, Curtis Johnson, Irene Spitsberg, Mark Gorman, Yan Gao
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Publication number: 20060121304Abstract: A protected article includes a substrate, and a protective structure overlying the substrate. The protective structure has a diffusion-barrier layer overlying the substrate, wherein the diffusion-barrier layer comprises at least about 70 percent by weight iridium, and a protective layer overlying the diffusion-barrier layer so that the diffusion-barrier layer is between the substrate and the protective layer. The protective layer is at least about 70 percent by weight of a platinum-group element. A ceramic thermal barrier coating may overlie the protective layer.Type: ApplicationFiled: December 3, 2004Publication date: June 8, 2006Applicant: GENERAL ELECTRIC COMPANYInventors: Mark Gorman, Ramgopal Darolia, Michael Gigliotti
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Publication number: 20060099080Abstract: A method of cooling a gas turbine engine component having a perforate metal wall includes providing a plurality of pores in the wall, wherein the pores extend substantially perpendicularly through the wall, and wherein the pores are covered and sealed closed at first ends thereof by a thermal barrier coating disposed over a first surface of the wall, and providing a plurality of film cooling holes in the wall, wherein the holes extend substantially perpendicularly through the wall and the thermal barrier coating. The method also includes providing cooling fluid to the plurality of pores and the plurality of film cooling holes along a second surface of the wall, channeling the cooling fluid through the pores for back side cooling an inner surface of the thermal barrier coating, and channeling the cooling fluid through the holes for film cooling an outer surface of the thermal barrier coating.Type: ApplicationFiled: November 9, 2004Publication date: May 11, 2006Inventors: Ching-Pang Lee, Ronald Bunker, Harvey Maclin, Ramgopal Darolia
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Publication number: 20060093801Abstract: A coating and process for depositing the coating on a substrate. The coating is a nickel aluminide overlay coating of predominantly the beta (NiAl) and gamma-prime (Ni3Al) intermetallic phases, and is suitable for use as an environmental coating and as a bond coat for a thermal barrier coating (TBC). The coating can be formed by depositing nickel and aluminum in appropriate amounts to yield the desired beta+gamma prime phase content. Alternatively, nickel and aluminum can be deposited so that the aluminum content of the coating exceeds the appropriate amount to yield the desired beta+gamma prime phase content, after which the coating is heat treated to diffuse the excess aluminum from the coating into the substrate to yield the desired beta+gamma prime phase content.Type: ApplicationFiled: December 1, 2004Publication date: May 4, 2006Applicant: General Electric CompanyInventors: Ramgopal Darolia, Joseph Rigney, Gillion Marijnissen, Eric Vergeldt, Annejan Kloosterman
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Publication number: 20060093850Abstract: 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.Type: ApplicationFiled: October 29, 2004Publication date: May 4, 2006Applicant: GENERAL ELECTRIC COMPANYInventors: Ramgopal Darolia, Joseph Rigney, William Walston
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Publication number: 20060093752Abstract: Methods for depositing an overlay coating on articles intended for use 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 of a thermal barrier coating system. The coating further contains at least one platinum group metal, preferably chromium, optionally one or more reactive elements, and optionally silicon. The coating is deposited by a process that entails forming a platinum group metal layer and at least one separate layer of other constituents of the coating, and then performing a diffusion heat treatment to yield the coating.Type: ApplicationFiled: October 29, 2004Publication date: May 4, 2006Applicant: GENERAL ELECTRIC COMPANYInventors: Ramgopal Darolia, Brett Boutwell, Mark Gorman
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Publication number: 20060093851Abstract: 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.Type: ApplicationFiled: October 29, 2004Publication date: May 4, 2006Applicant: GENERAL ELECTRIC COMPANYInventors: Ramgopal Darolia, William Walston