Abstract: A method (20) of fabricating a large component such as a gas turbine or compressor disk (32) from segregation-prone materials such as Alloy 706 or Alloy 718 when the size of the ingot required is larger than the size that can be predictably formed without segregations using known triple melt processes. A sound inner core ingot (12) is formed (22) to a first diameter (D1), such as by using a triple melt process including vacuum induction melting (VIM), electroslag remelting (ESR), and vacuum arc remelting (VAR). Material is than added (26) to the outer surface (16) of the core ingot to increase its size to a dimension (D2) required for the forging operation (28). A powder metallurgy or spray deposition process may be used to apply the added material. The added material may have properties that are different than those of the core ingot and may be of graded composition across its depth. This process overcomes ingot size limitations for segregation-prone materials.

Abstract: A method for in-frame repairing of a thermal barrier coating (12) on a gas turbine component includes cleaning a desired surface portion (10) of the component without removing the component from the gas turbine. The method also includes roughening the surface portion in-frame, applying a bond coat (68) to the surface portion in-frame, and applying a ceramic topcoat (70) to the bond coat, in-frame. A system (28) for cleaning the surface portion in-frame includes an abrasive media (34) having a state change characteristic occurring at a temperature lower than an operating temperature of the gas turbine so that the abrasive media changes from a solid state to another state allowing the media to exit the gas turbine during operation. The system also includes an abrasive media sprayer (36) to direct a spray of the abrasive media at the desired surface portion.

Abstract: A method (20) of fabricating a large component such as a gas turbine or compressor disk (32) from segregation-prone materials such as Alloy 706 or Alloy 718 when the size of the ingot required is larger than the size that can be predictably formed without segregations using known triple melt processes. A sound inner core ingot (12) is formed (22) to a first diameter (D1), such as by using a triple melt process including vacuum induction melting (VIM), electroslag remelting (ESR), and vacuum arc remelting (VAR). Material is than added (26) to the outer surface (16) of the core ingot to increase its size to a dimension (D2) required for the forging operation (28). A powder metallurgy or spray deposition process may be used to apply the added material. The added material may have properties that are different than those of the core ingot and may be of graded composition across its depth. This process overcomes ingot size limitations for segregation-prone materials.

Abstract: A method (20) of fabricating a large component such as a gas turbine or compressor disk (32) from segregation-prone materials such as Alloy 706 or Alloy 718 when the size of the ingot required is larger than the size that can be predictably formed without segregations using known triple melt processes. A sound inner core ingot (12) is formed (22) to a first diameter (D1), such as by using a triple melt process including vacuum induction melting (VIM), electroslag remelting (ESR), and vacuum arc remelting (VAR). Material is than added (26) to the outer surface (16) of the core ingot to increase its size to a dimension (D2) required for the forging operation (28). A powder metallurgy or spray deposition process may be used to apply the added material. The added material may have properties that are different than those of the core ingot and may be of graded composition across its depth. This process overcomes ingot size limitations for segregation-prone materials.

Abstract: A coating for a molybdenum-based substrate that may be a bi-layer coating. The lower layer may include a first molybdenum coating compound, such as Mo5Si3, doped with from about 0 to about 10% boron and/or silicon. The upper layer may include a second molybdenum coating compound, such as MoSi2, doped with from about 0 to about 20% silicon and/or aluminum. The bi-layer coating forms a protective SiO2 surface upon high temperature exposure in oxygen-containing atmospheres. The coating is capable of providing long-term oxidation resistance to molybdenum-based substrates up to about 1400° C. An additional thermal layer may be included.

Abstract: A method (20) of fabricating a large component such as a gas turbine or compressor disk (32) from segregation-prone materials such as Alloy 706 or Alloy 718 when the size of the ingot required is larger than the size that can be predictably formed without segregations using known triple melt processes. A sound inner core ingot (12) is formed (22) to a first diameter (D1), such as by using a triple melt process including vacuum induction melting (VIM), electroslag remelting (ESR), and vacuum arc remelting (VAR). Material is than added (26) to the outer surface (16) of the core ingot to increase its size to a dimension (D2) required for the forging operation (28). A powder metallurgy or spray deposition process may be used to apply the added material. The added material may have properties that are different than those of the core ingot and may be of graded composition across its depth. This process overcomes ingot size limitations for segregation-prone materials.

Abstract: A method for in-frame repairing of a thermal barrier coating (12) on a gas turbine component includes cleaning a desired surface portion (10) of the component without removing the component from the gas turbine. The method also includes roughening the surface portion in-frame, applying a bond coat (68) to the surface portion in-frame, and applying a ceramic topcoat (70) to the bond coat, in-frame. A system (28) for cleaning the surface portion in-frame includes an abrasive media (34) having a state change characteristic occurring at a temperature lower than an operating temperature of the gas turbine so that the abrasive media changes from a solid state to another state allowing the media to exit the gas turbine during operation. The system also includes an abrasive media sprayer (36) to direct a spray of the abrasive media at the desired surface portion.

Abstract: A method of adding material to a nickel-based superalloy component, such as a gas turbine rotor disk, without damaging the underlying material and without creating an unacceptable level of cracking. The method is advantageously applied in the repair of Alloy 706 turbine rotors having experienced operating failures in the steeple region of the disk. Once the damaged material is removed, replacement nickel-based superalloy material is added using a welding process that protects both the underlying material and the replacement material. The replacement material may be added by welding, with the preheat temperature maintained no lower than 100° C. below the aging temperature of the deposited alloy and with the interpass temperature maintained below the solution annealing temperature of the alloy. Alternatively, the replacement material may be preformed and welded to the original material using a friction welding process.

Abstract: A yttria stabilized zirconia ceramic thermal barrier coating (24) is applied to a substrate (22) using an oxy-acetylene spraying process by including in the coating a eutectic phase having a melting temperature sufficiently low to cause melting of the eutectic phase during the oxy-acetylene spraying process. The eutectic phase may be present in the powder (12) used for the spraying process, or it may be formed during the spraying process by the oxidation of a layer of metal applied to yttria stabilized zirconia particles. The use of an oxy-acetylene spraying process facilitates the application of the coating during in-frame repair of a gas turbine component.