PROCESS OF FILLING OPENINGS IN A COMPONENT

• US 20100059573A1
• Filed: 09/08/2008
• Published: 03/11/2010
• Est. Priority Date: 09/08/2008
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Peck, Arthur S., Penny, Christopher, Mukira, Charles Gitahi, Cui, Yan, Kottilingam, Srikanth Chandrudu, Miglietti, Warren Martin, Rauch, Steven
• Granted Patent: US 8,087,565 B2
• Time in Patent Office: Days
• US Class Current: 228/164
• CPC Class Codes: B23K 1/001 Sealing small holes in metal containers, e.g. tins
• CPC Class Codes: B23K 1/0018 Brazing of turbine parts
• CPC Class Codes: B23K 2101/001 Turbines
• CPC Class Codes: B23K 35/0244 Powders, particles or spheres; Preforms made therefrom
• CPC Class Codes: B23K 35/3033 Ni as the principal constituent
• CPC Class Codes: B23K 35/3046 Co as the principal constituent
• CPC Class Codes: Y10T 29/49318 Repairing or disassembling

Abstract

A process for filling openings, including blind holes, through-holes, and cavities, in high temperature components. The process entails forming a powder mixture by mixing particles of at least a base alloy and a second alloy that contains a sufficient amount of a melting point depressant to have a lower melting temperature than the base alloy. The powder mixture is combined with a binder and compacted to form a compacted preform, which is then heated to remove the binder and form a rigid sintered preform. The sintered preform is produced, or optionally is further shaped, to have a cross-sectional shape and dimensions to achieve a clearance of up to 200 micrometers with the opening, after which the preform is placed in the opening and diffusion bonded within the opening to form a brazement comprising the particles of the base alloy dispersed in a matrix formed by the second alloy.

Claims

1. A process of filling an opening in a component formed of nickel- or cobalt-base alloy, the process comprising:

forming a powder mixture by mixing particles of at least a base alloy and a second alloy, the base alloy constituting about 30 to about 90 weight percent of the powder mixture, the second alloy containing a sufficient amount of a melting point depressant to have a lower melting temperature than the base alloy;

combining the powder mixture with a binder and then compacting the combined powder mixture and binder to form a compacted preform;

heating the compacted preform to remove the binder and form a sintered preform;

placing the sintered preform in the opening, wherein the preform has a cross-sectional shape and dimensions to achieve a clearance of not greater than 200 micrometers with the opening; and

then

diffusion braze bonding the sintered preform within the opening to form a brazement within the opening comprising the particles of the base alloy dispersed in a matrix formed by the second alloy.

2. The process according to claim 1, wherein the sintered preform has a density of at least 90% of theoretical.

3. The process according to claim 1, wherein the base alloy consists essentially of, by weight, about 2.5 to 11% cobalt, 7 to 9% chromium, 3.5 to 11% tungsten, 4.5 to 8% aluminum, 2.5 to 6% tantalum, 0.02 to 1.2% titanium, 0.1 to 1.8% hafnium, 0.1 to 0.8% molybdenum, 0.01 to 0.17% carbon, up to 0.08% zirconium, up to 0.60 silicon, up to 2.0 rhenium, the balance nickel and incidental impurities.

4. The process according to claim 1, wherein the second alloy consists essentially of, by weight, about 9 to 10% cobalt, 11 to 16% chromium, 3 to 4% aluminum, 2.25 to 2.75% tantalum, 1.5 to 3.0% boron, up to 5% silicon, up to 1.0% yttrium, the balance nickel and incidental impurities.

5. The process according to claim 1, wherein the particles of the base and second alloys are mixed together at a weight ratio of about 30:

70 to about 90;

10, respectively.

6. The process according to claim 1, wherein the cross-sectional shape and dimensions of the sintered preform are achieved by shaping the sintered preform prior to placing the sintered preform in the opening.

7. The process according to claim 1, further comprising the step of defining an interlocking feature within the opening, wherein following the diffusion braze bonding step the brazement has a protrusion that interlocks with the interlocking feature of the opening.

8. The process according to claim 1, wherein the brazement completely closes the opening following the diffusion braze bonding step.

9. The process according to claim 1, wherein the sintered preform has a through-hole therein that defines a hole entirely through the brazement following the diffusion braze bonding step.

10. The process according to claim 1, wherein the component is a hot gas path component of a gas turbine.

11. A process of filling an opening in a hot gas path component of a gas turbine, the component being cast from a nickel- or cobalt-base alloy and the opening being formed by a rod that supported a core within the component during casting of the component, the process comprising:

forming a powder mixture by mixing particles of at least a base alloy and a second alloy, the base alloy constituting about 30 to about 90 weight percent of the powder mixture, the second alloy containing a sufficient amount of a melting point depressant to have a lower melting temperature than the base alloy;

combining the powder mixture with a binder and then compacting the combined powder mixture and binder to form a compacted preform;

heating the powder mixture to remove the binder and form a sintered preform having a cross-section larger than the opening;

shaping the sintered preform to produce a cross-sectional shape and dimensions to achieve a clearance of not greater than 200 micrometers with the opening;

placing the sintered preform in the opening; and

then

diffusion braze bonding the sintered preform within the opening to completely fill the opening with a brazement comprising the particles of the base alloy dispersed in a matrix formed by the second alloy.

12. The process according to claim 11, wherein the sintered preform has a density of at least 90% of theoretical.

13. The process according to claim 11, wherein the base alloy consists essentially of, by weight, about 9 to 11% cobalt, 8 to 8.8% chromium, 9.5 to 10.5% tungsten, 5.3 to 5.7% aluminum, 2.8 to 2.3% tantalum, 0.9 to 1.2% titanium, 1.2 to 1.6% hafnium, 0.5 to 0.8% molybdenum, 0.13 to 0.17% carbon, 0.03 to 0.08% zirconium, the balance nickel and incidental impurities.

14. The process according to claim 11, wherein the second alloy consists essentially of, by weight, about 9 to 10% cobalt, 11 to 16% chromium, 3 to 4% aluminum, 2.25 to 2.75% tantalum, 1.5 to 3.0% boron, up to 5% silicon, up to 1.0% yttrium, the balance nickel and incidental impurities.

15. The process according to claim 11, wherein the particles of the base and second alloys are mixed together at a weight ratio of about 40:

60 to about 70;

30, respectively.

16. The process according to claim 11, wherein the shaping step comprises a machining operation and the sintered preform does not have a recast surface when placed in the opening.

17. The process according to claim 11, further comprising the step of defining an interlocking feature within the opening, wherein following the diffusion braze bonding step the brazement has a protrusion that interlocks with the interlocking feature of the opening.

18. The process according to claim 11, wherein the brazement completely closes the opening following the diffusion braze bonding step.

19. The process according to claim 11, wherein the sintered preform has a through-hole therein that defines a hole entirely through the brazement following the diffusion braze bonding step.

20. The process according to claim 11, wherein the component is chosen from the group consisting of turbine buckets and turbine nozzles.