Method for preventing the corrosion of an impeller-shaft assembly of a turbomachine
A method for preventing corrosion of an impeller-shaft assembly of a turbomachine comprises the steps of assembling an impeller on a shaft in order to define an impeller-shaft assembly; plating the assembly by inserting the assembly into a plating bath; and coating at least a first predefined surface on the impeller and a second predefined surface on the shaft wherein the coating step is performed by spraying the predefined surfaces.
1. A method for preventing corrosion of an impeller-shaft assembly of a turbomachine, the method comprising:
assembling an impeller on a shaft in order to define an impeller-shaft assembly;
plating the assembly by inserting the assembly into a plating bath; and
coating at least a first predefined surface on the impeller and a second predefined surface on the shaft by spraying the predefined surfaces with a cold spray comprising particles of a nickel-based alloy or of stainless steel,
wherein the coating step is performed before the assembling step.
2. The method according to claim 1 , wherein the first predefined surface is a surface of a key slot on the impeller for attaching the impeller to the shaft.
3. The method according to claim 1 , wherein the second predefined surface is the surface of a key seat on the shaft.
4. The method according to claim 1 , wherein the assembling step comprises the sub-step of attaching a sleeve onto the shaft adjacent to the impeller; and the step of coating also comprises the step of coating a third predefined surface on the impeller and a fourth predefined surface on the shaft.
5. The method according to claim 4 , wherein the third predefined surface is a portion of surface of the impeller designed to face the sleeve.
6. The method according to claim 4 , wherein the fourth predefined surface is a portion of a lateral surface of the shaft designed to be arranged between the impeller and the sleeve.
7. The method according to claim 1 , wherein the step of plating is performed by electroless nickel plating.
8. A method for preventing corrosion of an impeller-shaft assembly of a turbomachine, the method comprising:
assembling an impeller on a shaft in order to define an impeller-shaft assembly;
plating the assembly by inserting the assembly into a plating bath; and
coating at least a first predefined surface on the impeller and a second predefined surface on the shaft by spraying the predefined surfaces with a thermal spray,
wherein the coating step is performed before the assembling step.
9. The method according to claim 8 , wherein the first predefined surface is a surface of a key slot on the impeller for attaching the impeller to the shaft.
10. The method according to claim 8 , wherein the second predefined surface is the surface of a key seat on the shaft.
11. The method according to claim 8 , wherein the assembling step comprises the sub-step of attaching a sleeve onto the shaft adjacent to the impeller; and the step of coating also comprises the step of coating a third predefined surface on the impeller and a fourth predefined surface on the shaft.
12. The method according to claim 11 , wherein the third predefined surface is a portion of surface of the impeller designed to face the sleeve.
13. The method according to claim 11 , wherein the fourth predefined surface is a portion of a lateral surface of the shaft designed to be arranged between the impeller and the sleeve.
14. The method according to claim 8 , wherein the step of plating is performed by electroless nickel plating.
15. A method for preventing corrosion of an impeller-shaft assembly of a turbomachine, the method comprising:
assembling an impeller on a shaft in order to define an impeller-shaft assembly;
plating the assembly by inserting the assembly into a plating bath; and
coating at least a first predefined surface on the impeller and a second predefined surface on the shaft by electroplating the predefined surfaces,
wherein the coating step is performed before the assembling step.
16. The method according to claim 15 , wherein the electroplating is performed by an electrolytic chromium or nickel plating process.
17. The method according to claim 15 , wherein the first predefined surface is a surface of a key slot on the impeller for attaching the impeller to the shaft.
18. The method according to claim 15 , wherein the second predefined surface is the surface of a key seat on the shaft.
19. The method according to claim 15 , wherein the assembling step comprises the sub-step of attaching a sleeve onto the shaft adjacent to the impeller; and the step of coating also comprises the step of coating a third predefined surface on the impeller and a fourth predefined surface on the shaft.
20. The method according to claim 19 , wherein the third predefined surface is a portion of surface of the impeller designed to face the sleeve.
21. The method according to claim 19 , wherein the fourth predefined surface is a portion of a lateral surface of the shaft designed to be arranged between the impeller and the sleeve.
22. The method according to claim 15 , wherein the step of plating is performed by electroless nickel plating.