Electroless metallic plating method for leak repair and prevention in liquid-cooled generator stator bars

• US 20060091742A1
• Filed: 11/02/2004
• Published: 05/04/2006
• Est. Priority Date: 11/02/2004
• Status: Abandoned Application

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Wang, Yu
• Application Number:
  US10/978,478
• Publication Number:
  US 20060091742A1
• Time in Patent Office: Days
• US Class Current: 310/54
• CPC Class Codes: C23C 18/1616 interior or inner surface
• CPC Class Codes: C23C 18/1651 Two or more layers only obtained by electroless plating
• CPC Class Codes: C23C 18/1841 with use of metal first
• CPC Class Codes: C23C 18/31 Coating with metals
• CPC Class Codes: H02K 15/0006 Disassembling, repairing or modifying dynamo-electric machines repairing of cooling fluid boxes H02K15/0093
• CPC Class Codes: H02K 15/0093 Manufacturing or repairing cooling fluid boxes, i.e. terminals of fluid cooled windings ensuring both electrical and fluid connection
• CPC Class Codes: Y10T 29/49009 Dynamoelectric machine

Abstract

A method of sealing a stator bar with an interior liquid pass for flow of coolant forming at least a portion of the stator bar, including electroless plating at least a portion of an interior wetted surface of the stator bar.

Claims

1. A method of sealing a stator bar with an interior liquid pass for flow of coolant forming at least a portion of said stator bar, comprising electroless plating at least a portion of an interior wetted surface of said stator bar.

2. A method as in claim 1, wherein before said electroless plating, at least target inside surfaces of said stator bar water pass are cleaned and the water pass is prepared to provide a catalyzed surface.

3. A method as in claim 2, wherein a catalyzed surface is produced by flushing the water pass with solutions that react to precipitate a catalytic metal in situ.

4. A method as in claim 3, wherein said catalytic metal is palladium.

5. A method as in claim 3, wherein the water pass is filled with an acidic stannous chloride solution, and then with a solution of palladium chloride.

6. A method as in claim 3, wherein the water pass is filled with a colloidal solution of palladium followed by filling with an accelerator solution.

7. A method as in claim 1, wherein select areas of the water pass interior surface are applied with an autocatalytic base coat.

8. A method as in claim 7, wherein the autocatalytic base coat is sprayed onto the select areas of the water pass interior surface.

9. A method as in claim 1, wherein the entire water pass is flooded with an electroless solution.

10. A method as in claim 9, wherein said water pass is flushed with electroless solution under pressure by defining the water pass system as a closed loop that is sealed and pressurized.

11. A method as in claim 1, wherein the electroless plating process is continued until a deposit layer of about 1 to 5 mils is achieved.

12. A method as in claim 1, wherein the electroless process is carried out after stator assembly.

13. A method as in claim 1, wherein a double-layered plating film is formed on said surface, including a first film and a second film applied over the first film.

14. A method as in claim 13, wherein the first film has a strong corrosion resistance and the second film is applied for at least one of air tightness, durability and corrosion resistance.

15. A method as in claim 1, wherein the water pass of the stator bar is plated before assembly and parts of the water pass are plated following assembly.

16. A stator bar end and a fitting receiving the end to define a seal substantially impermeable to liquid, the fitting having a chamber for receiving a liquid through an opening in the fitting and in communication with hollow strands forming at least a portion of said stator bar and for flow of the liquid through the hollow strands, wherein at least a portion of an interior surface of said fitting has a metallic layer disposed on a surface thereof, wherein said metallic layer is deposited by electroless plating.

17. A stator bar assembly as in claim 16, wherein said metallic layer extends substantially continuously over a junction of said fitting and said stator bar end.

18. A stator bar assembly as in claim 16, wherein said metallic layer extends substantially continuously over an entire liquid pass thereof.

19. A stator bar assembly as in claim 16, wherein said metallic layer is formed from at least one of nickel, chromium, zinc and copper.

20. A method of sealing a junction of a stator bar end and a fitting receiving the end, to define a corrosion resistant seal substantially impermeable to liquid, the fitting having a chamber for receiving a liquid through an opening in the fitting and in communication with hollow strands forming at least a portion of said stator bar end for flow of the liquid through the hollow strand, the method comprising the steps of:

flowing an electroless plating solution into and through said chamber of said fitting, said electroless plating solution flowing from a source of electroless plating solution comprising metal ions and a reducing agent.