RECOATING PROCESS AND RECOATED TURBINE BLADE

Abstract

Recoating process and recoated turbine blade are disclosed. The recoating process includes providing a coated turbine blade, then removing a portion of the thermal barrier coating system to form a partially-stripped turbine blade, then applying a bond recoat to the stripped region of the partially-stripped turbine blade; and then applying a thermal barrier recoat to the bond recoat to form a recoated turbine blade. The recoated turbine blade comprises the bond coating portion abutting the bond recoat, the thermal barrier coating portion abutting the thermal barrier recoat, and the stepped configuration. The coated turbine blade has a thermal barrier coating system positioned on a substrate. The partially-stripped turbine blade has a stripped region, a bond coating portion, a thermal barrier coating portion, and a stepped configuration.

Description

FIELD OF THE INVENTION

The present invention is directed to manufacturing processes and manufactured components. More particularly, the present invention is directed to recoating turbine blades and recoated turbine blades.

BACKGROUND OF THE INVENTION

Gas turbine blades are affected by operational use. Extremely high temperatures and long cycle times result in properties that can benefit from repair or replacement. For example, extremely high temperatures and exposure to certain materials, such as fuel, can result in oxidation, can result in fatigue, can result in damage, or other undesirable features. To reduce or eliminate such effects, turbine blades are replaced or repaired at periodic intervals.

Replacement of turbine blades can be expensive. Removal of the turbine blades for replacement from service can result in operational downtime that can reduce overall operational efficiency. As such, any reduction of such downtime can result in substantial improvements in overall operational efficiency of turbine systems utilizing turbine blades. Similarly, full stripping of coatings on turbine blades can be expensive due to time and materials expended in the stripping process and the recoating process.

Also, using more than one thermal barrier coating on a turbine blade can be undesirable aesthetically. For example, turbine blades with multiple thermal barrier coatings may have regions that look different from other regions. Individuals may improperly perceive that such differences relate to the quality or other properties of the turbine blade. Such improper perceptions can result in decreased use and/or sales of such turbine blades.

A recoating process and recoated turbine blade that do not suffer from one or more of the above drawbacks would be desirable in the art.

BRIEF DESCRIPTION OF THE INVENTION

In an exemplary embodiment, a recoating process includes providing a coated turbine blade, then removing a portion of the thermal barrier coating system to form a partially-stripped turbine blade having a stripped region, then applying a bond recoat to the stripped region of the partially-stripped turbine blade, and then applying a thermal barrier recoat to the bond recoat to form a recoated turbine blade. The coated turbine blade has a thermal barrier coating system positioned on a substrate.

In another exemplary embodiment, a recoating process includes providing a coated turbine blade having a thermal barrier coating system positioned on a substrate, then removing a portion of the thermal barrier coating system to form a partially-stripped turbine blade having a stripped region, a bond coating portion, a thermal barrier coating portion, and a stepped configuration, then applying a bond recoat to the stripped region of the partially-stripped turbine blade, and then applying a thermal barrier recoat to the bond recoat to form a recoated turbine blade. The recoated turbine blade includes the bond coating portion abutting the bond recoat, the thermal barrier coating portion abutting the thermal barrier recoat, and the stepped configuration.

In another exemplary embodiment, a recoated turbine blade includes a substrate, a bond coat portion abutting a bond recoat, a thermal barrier coating portion abutting a thermal barrier recoat, a stepped configuration of the bond coating portion, the bond coating, the thermal barrier portion, and the thermal barrier coating on the substrate. The bond coat portion and the thermal barrier coating portion include post-operational features.

Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of an exemplary recoating process.

FIG. 2 is a schematic view of a thermal barrier coating system of a coated turbine blade during a removing step of an exemplary recoating process according to the disclosure.

FIG. 3 is a schematic view of the coated turbine blade of FIG. 2.

FIG. 4 is a schematic view of a thermal barrier coating system of a coated turbine blade during a removing step of an exemplary recoating process according to the disclosure.

FIG. 5 is a schematic view of the coated turbine blade of FIG. 4.

FIG. 6 is a schematic view of a thermal barrier coating system of a coated turbine blade during a recoating step of an exemplary recoating process according to the disclosure.

FIG. 7 is a schematic view of the coated turbine blade of FIG. 6.

FIG. 8 is a schematic view of a thermal barrier coating system of a coated turbine blade during a recoating step of an exemplary recoating process according to the disclosure.

FIG. 9 is a schematic view of the coated turbine blade of FIG. 8.

Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.

DETAILED DESCRIPTION OF THE INVENTION

Provided is an exemplary recoating process and recoated turbine blade. Embodiments of the present disclosure, for example, in comparison to processes and coated articles without partial stripping and partial recoating, permit operational downtime to be reduced, permit selective repair and replacement of turbine blades, permit conserved use of materials in recoating turbine blades, permit materials to be inspected after removal of a thermal barrier coating and/or bond coat prior to recoating (for example, permitting inspection of a base material), permit damage from complete stripping to be reduced or eliminated, or a combination thereof.

FIG. 1 schematically shows a recoating process 100. The recoating process 100 includes providing a coated turbine blade 201 (step 102), as is further described in the embodiments shown in FIGS. 2-5, removing a portion of a thermal barrier coating system 203 (step 104), as is further described in the embodiments shown in FIGS. 2-5, applying a bond recoat 601 (step 106), as is further described in the embodiments shown in FIGS. 6-7, and applying a thermal barrier recoat 801 to the bond recoat 601 (step 108), as is further described in the embodiments shown in FIGS. 8-9.

The coated turbine blade 201 is any suitable blade, bucket, vane, or air foil. Referring to FIG. 2, the coated turbine blade 201 has a thermal barrier coating system 203 positioned on a substrate 205. The substrate 205 is any suitable metal material, metallic material, alloy, superalloy, or combination thereof. Suitable alloys include, but are not limited to, nickel-based alloys and cobalt-based alloys.

The thermal barrier coating system 203 is any suitable material(s) capable of providing thermal resistance for the coated turbine blade 201. In one embodiment, the thermal barrier coating system 203 includes a bond coating 202 and a thermal barrier coating 204. The bond coat 202 includes one or more bond coat materials, such as, MCrAlY (where M is a metal element), NiCrAlY, CoNiCrAlY, FeNiCrAlY, or a combination thereof. The thermal barrier coating 204 includes ceramics, yttria-stabilized zirconia, gadolinium zirconate, rare earth zirconates, or a combination thereof.

The removing of the portion of the thermal barrier coating 203 (step 104) forms a partially-stripped turbine blade 209 having a stripped region 211, for example, as is shown in FIGS. 2 and 4. As used herein, the term “partially-stripped” refers to having a portion but not all of the thermal barrier coating system 203 being removed. The portion includes part or all of the thermal barrier coating 204. In one embodiment, the portion includes part of the bond coating 202. In one embodiment, the removing (step 104) is by a stripping method, for example, water-jet stripping, grit-blast stripping, acid stripping, or a combination thereof. The removing (step 104) is a single-step process or a multiple-step process (for example, with an individual step for stripping the all or a portion of thermal barrier coating portion 204 and an individual step for stripping a portion of the bond coating 202). In one embodiment, the removing (step 104) is performed without removal of the coated turbine blade 201 from a turbine system (not shown) or after removal of the coated turbine blade 201, such as, a power generation system or a turbine engine.

The stripped region 211 extends into the partially-stripped turbine blade 209, for example, into a thermal barrier coating portion 207 of the partially-stripped turbine blade 209 and a bond coat portion 213 of the partially-stripped turbine blade 209. In one embodiment, the stripped region 211 has a stepped configuration, for example, as a plurality of cascading layers arranged in a step-like manner.

As shown in FIGS. 2-3, in one embodiment, the partially-stripped turbine blade 209 includes the bond coat portion 213 and the thermal barrier coating portion 207 prior to the applying of the bond recoat 601 (step 106) (as shown if FIGS. 6-7) and the applying of the thermal barrier recoat 801 (step 108) (as shown in FIGS. 8-9). As is shown in FIGS. 4-5, in one embodiment, the partially-stripped turbine blade 209 includes the bond coat portion 213 and is substantially devoid of the thermal barrier coating portion 207 (see FIGS. 2-3) and/or the thermal barrier coating 204 of the thermal barrier coating system 203 prior to the applying of the bond recoat 601 (step 106) and applying of the thermal barrier recoat 801 (step 108).

In one embodiment, the method 100 includes one or more inspection steps (not shown). The inspection steps are prior to the removing (step 104) and/or after the removing (step 104) but prior to the applying of the bond recoat 601 (step 106). The one or more inspection steps are by any suitable inspection techniques. Suitable techniques include, but are not limited to, non-destructive techniques and destructive techniques. The one or more inspection steps identify regions to be removed and/or recoated, for example, due to identifiable surface features.

The bond recoat 601 and the thermal barrier recoat 801 are applied to the partially-stripped turbine blade 209 to predetermined regions by any suitable processes. The bond recoat 601 includes material similar to, compatible with, or identical to the bond coating 202. The thermal barrier recoat 801 includes material similar to, compatible with, or identical to the thermal barrier coating 204. Suitable processes for applying the bond recoat 601 and/or the thermal barrier recoat 801 include, but are not limited to, air plasma spray, high-velocity oxy-fuel spray, suspension thermal spray, chemical vapor deposition, electron beam physical vapor deposition, physical vapor deposition, other suitable application processes, or a combination thereof.

As shown in FIGS. 6-7, the applying of the bond recoat 601 (step 106) is to the stripped region 211 of the partially-stripped turbine blade 209. In one embodiment, the applying of the bond recoat 601 (step 106) includes applying a first bond recoat to the substrate and applying a second bond recoat to the first bond recoat. Any suitable number of recoat steps are used. In one embodiment, the applying of the bond recoat 601 (step 106) is devoid of masking. In one embodiment, the applying of the bond recoat 601 (step 106) to the partially-stripped turbine blade 209 does not apply the bond recoat 601 outside of the stripped region 211 of the partially-stripped turbine blade 209. In another embodiment, the applying of the bond recoat 601 (step 106) to the partially-stripped turbine blade 209 applies the bond recoat 601 outside of the stripped region 211 of the partially-stripped turbine blade 209.

As shown in FIGS. 8-9, the applying of the thermal barrier recoat 801 (step 108) forms a recoated turbine blade 901. In one embodiment, the applying of the thermal barrier recoat 801 (step 108) is devoid of masking. In one embodiment, the applying of the thermal barrier recoat 801 (step 108) to the partially-stripped turbine blade 209 does not apply the thermal barrier recoat 801 outside of the stripped region 211 of the partially-stripped turbine blade 209. In another embodiment, the applying of the thermal barrier recoat 801 (step 108) to the partially-stripped turbine blade 209 applies the thermal barrier recoat 801 outside of the stripped region 211 of the partially-stripped turbine blade 209.

After the applying of the bond recoat 601 (step 106) and the applying of the thermal barrier recoat 801 (step 108), the recoated turbine blade 901 is formed. In one embodiment, the recoated turbine blade 901 includes the bond recoat 601 (see FIG. 8), and the bond recoat 601 abuts the bond coating portion 213 (see FIG. 8) of the thermal barrier coating system 203. In a further embodiment, the bond coating portion 213 differs from the bond recoat 601 by being post-operational, thereby having been oxidized, heat-exposed (for example, to a temperature above 1,500° F.), fuel-exposed, otherwise impacted by operational use, or a combination thereof.

In one embodiment, the recoated turbine blade 901 includes the thermal barrier recoat 801, and the thermal barrier recoat 801 abuts the thermal barrier coating portion 207 of the thermal barrier coating system 203. In a further embodiment, the thermal barrier coating portion 207 differs from the thermal barrier recoat 801 by being post-operational, thereby having been oxidized, heat-exposed (for example, to a temperature above 1,500° F.), fuel-exposed, otherwise impacted by operational use, or a combination thereof.

The arrangement within the recoated turbine blade 901 of the bond coat portion 213, the bond recoat 601, the thermal barrier coating portion 207 (if present), and the thermal barrier recoat 801 is any suitable configuration. Suitable configurations include, but are not limited to, a stepped configuration as is described above, an overlapping configuration, a tapered configuration with a blending of materials between layers, having mismatched layers (for example, the bond coat portion 213 and the bond recoat 601 being slightly out of relative alignment and/or the thermal barrier coating portion 207 and the thermal barrier recoat 801 being slightly out of relative alignment), any other suitable configuration, or a combination thereof.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A recoating process, comprising:

providing a coated turbine blade, the coated turbine blade having a thermal barrier coating system positioned on a substrate; then

removing a portion of the thermal barrier coating system to form a partially-stripped turbine blade having a stripped region; then

applying a bond recoat to the stripped region of the partially-stripped turbine blade; and then

applying a thermal barrier recoat to the bond recoat to form a recoated turbine blade.

2. The recoating process of claim 1, wherein the thermal barrier coating system includes a thermal barrier coating and a bond coat.

3. The recoating process of claim 1, wherein the removing is by water-jet stripping.

4. The recoating process of claim 1, wherein the partially-stripped turbine blade comprises a bond coat portion and a thermal barrier coating portion prior to the applying of the bond recoat and the applying of the thermal barrier recoat.

5. The recoating process of claim 1, wherein the partially-stripped turbine blade comprises a bond coat portion and is substantially devoid of a thermal barrier coating of the thermal barrier coating system prior to the applying of the bond recoat and applying of the thermal barrier recoat.

6. The recoating process of claim 1, wherein the partially-stripped turbine blade has a stepped configuration.

7. The recoating process of claim 1, comprising inspecting the partially-stripped turbine blade prior to applying the bond recoat.

8. The recoating process of claim 1, wherein the applying of the bond recoat to the partially-stripped turbine blade includes applying a first bond recoat to the substrate and applying a second bond recoat to the first bond recoat.

9. The recoating process of claim 1, wherein the applying of the bond recoat is devoid of masking.

10. The recoating process of claim 1, wherein the applying of the bond recoat to the partially-stripped turbine blade does not apply the bond recoat outside of the stripped region of the partially-stripped turbine blade.

11. The recoating process of claim 1, wherein the applying of the bond recoat to the partially-stripped turbine blade applies the bond recoat outside of the stripped region of the partially-stripped turbine blade.

12. The recoating process of claim 1, wherein the applying of the thermal barrier recoat is devoid of masking.

13. The recoating process of claim 1, wherein the applying of the thermal barrier recoat to the partially-stripped turbine blade does not apply the thermal barrier recoat outside of the stripped region of the partially-stripped turbine blade.

14. The recoating process of claim 1, wherein the applying of the thermal barrier recoat to the partially-stripped turbine blade applies the thermal barrier recoat outside of the stripped region of the partially-stripped turbine blade.

15. The recoating process of claim 1, wherein the recoated turbine blade comprises the bond recoat, and the bond recoat abuts a bond coating portion of the thermal barrier coating system.

16. The recoating process of claim 1, wherein the recoated turbine blade comprises the thermal barrier recoat, and the thermal barrier recoat abuts a thermal barrier coating portion of the thermal barrier coating system.

17. The recoating process of claim 1, wherein the recoated turbine blade has a stepped configuration.

18. The recoating process of claim 1, wherein the removing of the portion of the thermal barrier coating system from the coated turbine blade is performed without removal of the coated turbine blade from a turbine system.

19. A recoating process, comprising:

providing a coated turbine blade, the coated turbine blade having a thermal barrier coating system positioned on a substrate; then

removing a portion of the thermal barrier coating system to form a partially-stripped turbine blade having a stripped region, a bond coating portion, a thermal barrier coating portion, and a stepped configuration; then

applying a bond recoat to the stripped region of the partially-stripped turbine blade; and then

applying a thermal barrier recoat to the bond recoat to form a recoated turbine blade;

wherein the recoated turbine blade comprises the bond coating portion abutting the bond recoat, the thermal barrier coating portion abutting the thermal barrier recoat, and the stepped configuration.

20. A recoated turbine blade, comprising:

a substrate;

a bond coat portion abutting a bond recoat;

a thermal barrier coating portion abutting a thermal barrier recoat; and

a stepped configuration of the bond coating portion, the bond coating, the thermal barrier portion, and the thermal barrier coating on the substrate;

wherein the bond coat portion and the thermal barrier coating portion include post-operational features.