Insert for hot isostatic pressing treatment

Abstract

An insert fixture for use in the manufacture of a single crystal component by a hot isostatic pressing process. The insert fixture comprising: at least a lower plate separated from an upper plate by interconnecting members. The upper plate comprises at least a slot for the insertion of the single crystal component. The lower plate features a related engagement feature for engaging with the single crystal component. The insert fixture may be cast from a ceramic material. The insert fixture may be cast from an alumina ceramic or molybdenum alloy. The interconnecting members may be made from a molybdenum alloy.

Claims

1. An assembly comprising: an insert fixture configured for manufacture of a single crystal component by a hot isostatic pressing process, the insert fixture comprising: a lower plate separated from an upper plate by interconnecting members, wherein the upper plate comprises a slot for insertion of the single crystal component and the lower plate comprises a related engagement feature for engaging with the single crystal component; and a cast turbine engine component comprising nickel or cobalt based superalloy, wherein the cast turbine engine component is retained by the slot and the engagement feature.

2. The assembly as claimed in claim 1, wherein the upper and lower plates in the insert fixture are composed of a ceramic material.

3. The assembly as claimed in claim 1, wherein the upper and lower plates in the insert fixture are composed of an alumina ceramic.

4. The assembly according to claim 1, wherein the interconnecting members are made from a molybdenum alloy.

5. The assembly as claimed in claim 1, wherein a spacer is added to the base of the lower plate.

6. The assembly as claimed in claim 1, wherein the upper plate comprises a plurality of slots and the lower plate comprises a plurality of corresponding engagement feature.

7. The assembly as claimed in claim 1, wherein the engagement feature comprises a slot in the lower plate.

8. The assembly as claimed in claim 1, wherein the engagement feature comprises a clip mounted to the lower plate.

9. The assembly as claimed in claim 1, wherein the slot in the upper plate comprises an insert liner.

10. The assembly as claimed in claim 9, wherein the insert liner is made from alumina or a molybdenum alloy.

11. The assembly as claimed in claim 10, wherein the insert liner is coated in aluminium oxide.

12. A method of hot isostatic pressing (HIP) processing a single crystal component, the method comprising the steps of: placing the assembly of claim 1 into an HIP processing vessel; and treating the cast turbine engine component within the HIP processing vessel in an HIP atmosphere.

13. The method as claimed in claim 12 wherein the HIP atmosphere comprises a temperature of up to 1500° C. and a pressures of up to 150 MPa.

14. The method as claimed in claim 12, wherein the cast turbine engine component is a turbine blade.

15. The assembly as claimed in claim 1, wherein the upper and lower plates in the insert fixture are composed of molybdenum alloy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments will now be described by way of example only, with reference to the Figures, in which:

(2) FIG. 1 is a sectional side view of a gas turbine engine;

(3) FIG. 2 is a sectional view of a portion of the insert fixture for HIP treatment of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

(4) With reference to FIG. 1, a gas turbine engine is generally indicated at 10, having a principal and rotational axis 11. The engine 10 comprises, in axial flow series, an air intake 12, a propulsive fan 13, an intermediate pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, an intermediate pressure turbine 18, a low-pressure turbine 19 and an exhaust nozzle 20. A nacelle 21 generally surrounds the engine 10 and defines both the intake 12 and the exhaust nozzle 20. The gas turbine engine 10 works in the conventional manner so that air entering the intake 12 is accelerated by the fan 13 to produce two air flows: a first air flow into the intermediate pressure compressor 14 and a second air flow which passes through a bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 14 compresses the air flow directed into it before delivering that air to the high pressure compressor 15 where further compression takes place.

(5) The compressed air exhausted from the high-pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines 17, 18, 19 before being exhausted through the nozzle 20 to provide additional propulsive thrust. The high 17, intermediate 18 and low 19 pressure turbines drive respectively the high pressure compressor 15, intermediate pressure compressor 14 and fan 13, each by suitable interconnecting shaft.

(6) Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines. Further the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.

(7) In the HIP process, a number of baskets are typically used to support the components within the pressure vessel. Each basket can be of a rivet design, featuring a cylindrical outer wall and inner internal support structure. Coupled to these is a base plate that is provided with a series of holes to avow the gas to flow between the different baskets. The baskets are then stacked in any suitable configuration before being inserted into the HIP processing vessel. This could be for example 1, 2, 3, 4, 5, 6, 7 or greater number of baskets stacked on top of each other. Each basket is also provided with a number of thermocouples to monitor the temperature conditions inside each basket.

(8) The insert fixture 30 for placing in a HIP processing basket is shown in FIG. 2. This insert basket comprises two or more plates, which form at least an upper 32 and a lower 34 plate. These plates are separated from each other by a plurality of interconnecting members 36. The reference to upper and lower is relative to the operation of the device, in which the lower plate is placed closer to the base of the HIP basket than the upper plate. The upper plate features at least a slot 38 through it. However, the upper plate may also feature a plurality of slots. The lower plate features at least an engagement feature 40. The lower plate may feature a plurality of engagement means. The engagement means on the lower plate are configured to be positioned relative to the slots in the upper plate. The alignment configuration means that objects that are undergoing HIP processing can be inserted through the slot at the top of the upper plate and into the engagement means of the lower plate. This allows the object to be maintained in a fixed position during processing. The engagement means on the lower plate may be an engagement clip. The engagement means on the lower plate could also be a slot; this is the configuration as shown in FIG. 2. The person skilled in the art will appreciate that any suitable engagement means could be employed on the lower plate, and that the choice may depend on the geometry of the component that is being processed. The lower plate may be provided with a spacer 46 on its base, such that it does not directly contact the base of the HIP processing basket. The spacers may be part of the interconnecting members and extend through the lower plate. In the example shown in FIG. 2 the, turbine blades 44 have been inserted into the insert at a fixed orientation. The blades are inserted by sliding the root of the blade through the slot and then into the lower plates engagement means-slot. The slots are positioned and oriented such that none of the blades contact any part of another blade. The use of the insert, therefore, overcomes the limitations of the blades touching in the basket.

(9) The insert fixture may be formed from sheet material or cast to form the desired shape. The fixture may be made from any suitable material such as ceramics or alloy metals. Alumina ceramic could for example be used as this material has good wear resistance allowing it to be used multiple times. Other suitable ceramics would be alumina. Suitable metals and alloys may include molybdenum lanthanum oxide and titanium zirconium molybdenum (TZM). The interconnecting members can be made from any suitable material. For Example, this could be the use of molybdenum. These materials are desirable due to their high melting points and relatively high strengths. If a clip is used rather than a slot this could be made from molybdenum lanthanum oxide or titanium zirconium molybdenum. Lining the slot in the upper plate and or lower plate may be an alumina insert 42. This prevents the blade object being processed from directly contacting the plate, as this may have effects on the effect of the treatment. The plates may be further coated. This could be though the use of a suitable oxide. Such an oxide may be aluminium oxide Al.sub.2O.sub.3.

(10) In processing, the insert is positioned into the HIP basket before the blades are loaded into each cell. As the insert may only have a single orientation for insertion into the basket, it means that the processing conditions on each blade can be reproduced between batches. Once the insert has been filled with the blades the basket can then be loaded onto the others in the vessel and sealed. The HIP processing is then carried out in an argon atmosphere, and the relative openness of the cells allows the gas to pass to all the blades in an unrestricted way. This process removes the microvoids formed during the production of the single crystal blades and thus reduces the requirements to scrap or rework these damaged blades. The pressures and temperatures within the HIP vessel may be up to 1500° C. and up to 150 MPa.

(11) It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.