Method for repairing turbine component by application of thick cold spray coating

1. A method of repairing a Ni-based alloy component, the method comprising:

preparing a surface to be repaired of the Ni-based alloy component for receiving a cold spray repair, wherein the surface to be repaired has a damaged portion that includes a defect therein, wherein the defect extends about 1.5 mm to about 6 mm into the surface of the Ni-based alloy component;

spraying Ni-based alloy particles carried by a high pressure gas stream onto the surface of the Ni-based alloy component to form a coating within the defect of the damaged portion of the surface, wherein the Ni-based alloy particles have a melting point; and wherein the Ni-based alloy particles are sprayed at a spray temperature that is less than the melting point of the Ni-based alloy particles, and wherein the spray temperature is about 500° C. to about 1100° C.;

removing any over-spray on the surface of the Ni-based alloy component;

solution heat treating the coating on the surface of the Ni-based alloy component, wherein heat treating the coating comprises heating the coating to a heat treatment temperature of about 900° C. to about 1300° C. for a period of about 30 minutes to about 5 hours; and

after solution heat treating the coating, quenching the coating from the heat treatment temperature to a temperature that is less than a gamma-prime temperature and a gamma-double prime solvus temperature of the Ni-based alloy particles such that a matrix phase of gamma nickel and gamma-prime primary precipitate is present in the coating.

2. The method of claim 1 , wherein the coating has a thickness of about 1.5 mm to about 6 mm within the defect.

3. The method of claim 1 , wherein the coating has a thickness of about 2.5 mm to about 5 mm within the defect.

4. The method of claim 1 , wherein the coating has a thickness of about 3.0 mm to about 5 mm within the defect.

5. The method of claim 1 , wherein the Ni-based alloy particles are sprayed at a spray temperature of about 650° C. to about 800° C.

6. The method of claim 1 , wherein the high pressure gas stream is selected from the group consisting of helium gas, nitrogen gas, atmospheric air, argon, and mixtures thereof.

7. The method of claim 1 , wherein the Ni-based alloy particles have a composition identical to the Ni-based alloy component as originally formed.

8. The method of claim 1 , wherein the Ni-based alloy particles have an average size of about 1 μm to about 100 μm.

9. The method of claim 1 , wherein the Ni-based alloy particles have an average size of about 5 μm to about 50 μm.

10. The method of claim 1 , wherein the coating has a tensile strength that is about 100% to about 130% of the tensile strength of the original Ni-based alloy component, and wherein the coating has a porosity of about 5% or less after heat treatment.

11. The method of claim 1 , wherein preparing a surface to be repaired comprises removing an existing material or layer from the surface so that the coating is formed directly on the Ni-based alloy material of the Ni-based alloy component so as to bond directly thereto.

12. The method of claim 1 , wherein the coating fills the defect to restore the surface of the Ni-based alloy component.

13. The method of claim 1 , spraying the Ni-based alloy particles onto the surface of the Ni-based alloy component to form the coating restores the component to its original dimensions.

14. The method of claim 1 , wherein spraying the Ni-based alloy particles onto the surface of the Ni-based alloy component to form the coating within the defect of the damaged portion of the surface, comprises spraying multiple streams of Ni-based alloy particles onto the surface of the Ni-based alloy component to form the coating within the defect of the damaged portion of the surface.

15. The method of claim 1 , wherein the coating comprises a hybrid coating having a combination of materials.

16. The method of claim 1 , wherein the coating comprises a graded coating composition.

17. The method of claim 1 , further comprising:

intermittently changing from the Ni-based alloy particles to a second particle feedstock during the spraying the stream.