Method for adhering a coating to a substrate structure

1. A method for adhering a coating to a substrate structure, the method comprising:

selecting a substrate structure having an outer surface oriented substantially parallel to a direction of radial stress;

modifying an entirety of the outer surface to provide a textured region having steps to adhere a coating thereto; and

applying a coating to extend over at least a portion of the textured region and to adhere to the outer surface;

wherein the modifying of the outer surface comprises forming each of the steps to define a nose at which first ends of shear and bearing surfaces meet to define a first angle and a knee at which second ends of the shear and bearing surfaces meet to define a second angle oppositely oriented relative to the first angle,

the shear surface of each step being substantially straight along an entirety thereof and parallel with each of the respective shear surfaces of the other steps, the bearing surface of each step being curved along an entirety thereof and parallel with each of the respective bearing surfaces of the other steps such that corresponding portions of each of the steps are oriented in parallel with one another and each of the steps are oriented approximately perpendicular to the direction of radial stress so as to resist deformation of the coating relative to the substrate structure.

2. A method as described in claim 1 , further comprising orienting the steps approximately along a circumferential direction of the substrate structure.

3. A method as described in claim 1 , further comprising forming each of the steps so as to define the bearing surface against which a coating may bear so as to resist creep through compression of the coating.

4. A method as described in claim 3 , further comprising orienting the bearing surface within approximately 15 degrees relative to perpendicularity with respect to the direction of radial stress.

5. A method as described in claim 3 , further comprising orienting the bearing surface so as to form an angle that is less than about 90 degrees relative to the direction of radial stress.

6. A method as described in claim 3 , further comprising orienting the bearing surface so as to form an angle that is between about 90 degrees and about 45 degrees relative to the direction of radial stress.

7. A method as described in claim 3 , further comprising orienting the bearing surface approximately about 45 degrees relative to the direction of radial stress.

8. A method as described in claim 1 , further comprising forming each of the steps so as to define a discontinuous knee including a secondary shear surface recessed from the shear surface.

9. A method as described in claim 1 ;

wherein said applying a coating is performed such that said coating adheres directly to the outer surface;

further comprising depositing the coating at a thickness characteristic of a process selected from spraying, sintering, flame spraying, vapor deposition, sputtering, and electro-less coating.

10. A method as described in claim 1 , wherein the substrate structure is a turbine airfoil.

11. A method as described in claim 1 , wherein the substrate structure is a turbine disk.

12. A method as described in claim 1 , wherein the modifying comprises machining the outer surface.

13. A method as described in claim 1 , wherein the modifying comprises one or more of grinding, laser cutting, chemical etching, burnishing, embossing, stamping, cold forming, casting, molding or forging the outer surface.

14. A method for adhering a coating to a substrate structure, the method comprising:

selecting a substrate structure having an outer surface oriented substantially parallel to a direction of radial stress;

modifying an entirety of the outer surface to provide a textured region having steps to adhere a coating thereto, the modifying comprising forming each of the steps to define a nose at which first ends of shear and bearing surfaces meet to define a first angle and a knee at which second ends of the shear and bearing surfaces meet to define a second angle, which is oppositely oriented relative to the first angle; and

applying a coating to extend over at least a portion of the textured region and to adhere to the outer surface,

wherein the steps are oriented approximately perpendicular to the direction of radial stress so as to resist deformation of the coating relative to the substrate structure and the first and second angles are acute and of substantially equal magnitude such that the nose overhangs the knee of each step relative to a direction defined perpendicularly with respect to the direction of radial stress.

15. The method according to claim 14 , wherein the steps are parallel and each of the first and second angles of each of the steps are acute and of substantially equal magnitude.

16. A method for adhering a coating to a substrate structure, the method comprising:

selecting a substrate structure having an outer surface oriented substantially parallel to a direction of radial stress;

modifying an entirety of the outer surface to provide a textured region having grooves to adhere a coating thereto, the modifying comprising forming each of the grooves to define a nose at which first ends of shear and bearing surfaces meet to define a first angle and a knee at which second ends of the shear and bearing surfaces meet to define a second angle, which is oppositely oriented relative to the first angle; and

applying a coating to extend over at least a portion of the textured region and to adhere to the outer surface;

wherein the shear surface of each step is substantially straight along an entirety thereof and parallel with each of the respective shear surfaces of the other steps, the bearing surface of each step is curved along an entirety thereof and parallel with each of the respective bearing surfaces of the other steps and the steps are oriented approximately perpendicular to the direction of radial stress so as to resist deformation of the coating relative to the substrate structure.