U.S. patent application number 13/267617 was filed with the patent office on 2013-04-11 for repair methods for cooled components.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is Ronald Scott Bunker. Invention is credited to Ronald Scott Bunker.
Application Number | 20130086784 13/267617 |
Document ID | / |
Family ID | 47002717 |
Filed Date | 2013-04-11 |
United States Patent
Application |
20130086784 |
Kind Code |
A1 |
Bunker; Ronald Scott |
April 11, 2013 |
REPAIR METHODS FOR COOLED COMPONENTS
Abstract
A method for repairing a component is provided, where the
component has a substrate comprising an outer surface and an inner
surface and defining one or more grooves. Each groove extends at
least partially along the outer surface of the substrate. The
component further includes a structural coating, a bond coating,
and a thermal bather coating. The groove(s) and the structural
coating define one or more channels for cooling the component. The
repair method includes removing the thermal barrier and bond
coatings, removing at least a portion of the structural coating in
a vicinity of a damaged portion of the component, performing a
repair operation on the damaged portion of the component, applying
a structural coating at least in a vicinity of the repaired portion
of the component, and applying a bond coating and a thermal barrier
coating. Additional repair methods are also provided.
Inventors: |
Bunker; Ronald Scott;
(Waterford, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bunker; Ronald Scott |
Waterford |
NY |
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
SCHENECTADY
NY
|
Family ID: |
47002717 |
Appl. No.: |
13/267617 |
Filed: |
October 6, 2011 |
Current U.S.
Class: |
29/402.03 |
Current CPC
Class: |
F05D 2260/204 20130101;
C23C 28/321 20130101; Y02T 50/60 20130101; F05D 2230/80 20130101;
Y10T 29/49746 20150115; F01D 5/187 20130101; Y02T 50/6765 20180501;
F01D 5/005 20130101; B23P 6/002 20130101; F01D 5/288 20130101; F02C
7/12 20130101; Y02T 50/672 20130101; Y02T 50/676 20130101; Y10T
29/49721 20150115; C23C 4/00 20130101; C23C 28/3455 20130101 |
Class at
Publication: |
29/402.03 |
International
Class: |
B23P 6/00 20060101
B23P006/00 |
Claims
1. A method for repairing a component having a substrate comprising
an outer surface and an inner surface, wherein the inner surface
defines at least one hollow, interior space, wherein the substrate
defines one or more grooves, wherein each groove extends at least
partially along the outer surface of the substrate, the component
further comprising a structural coating disposed over at least a
portion of the outer surface of the substrate, a bond coating
disposed over the structural coating, and a thermal barrier coating
disposed over the bond coating, wherein the one or more grooves and
the structural coating together define one or more channels for
cooling the component, the repair method comprising: removing the
thermal barrier coating; removing the bond coating; removing at
least a portion of the structural coating in a vicinity of a
damaged portion of the component; performing a repair operation on
the damaged portion of the component; applying a structural coating
at least in a vicinity of the repaired portion of the component,
wherein the structural coating is applied without the use of a
sacrificial filler, such that the structural coating is applied
over open ones of the one or more grooves; applying a bond coating
over the structural coating; and applying a thermal barrier coating
over the bond coating.
2. The repair method of claim 1, wherein each groove has a base and
a top, and wherein each of the respective one or more grooves
narrows at the respective top thereof, such that each groove
comprises a re-entrant shaped groove.
3. The repair method of claim 2, wherein the applied structural
coating completely bridges the respective grooves, such that the
applied structural coating seals the respective cooling
channels.
4. The repair method of claim 2, wherein the applied structural
coating defines one or more porous gaps such that the applied
structural coating does not completely bridge each of the
respective grooves.
5. The repair method of claim 1, wherein performing the repair
operation comprises performing one or more of: locally machining a
portion of at least one of the one or more grooves; forming one or
more additional grooves in the substrate; and removing one or more
grooves from the substrate.
6. The repair method of claim 1, wherein each groove has at least
one discharge end, the repair method further comprising forming a
crater prior to the step of applying the structural coating, such
that the crater is in fluid connection with the respective
discharge end for each groove, wherein the applied structural
coating does not completely bridge each of the one or more craters,
such that each crater defines a film exit.
7. The repair method of claim 6, wherein a portion of the applied
structural coating is deposited in the one or more craters, the
repair method further comprising removing at least some of the
applied structural coating deposited in each crater to form the
film hole for the respective channel.
8. The repair method of claim 1, wherein each groove has at least
one discharge end, the repair method further comprising: forming a
run-out region adjacent to the respective discharge point for each
groove, wherein the run-out region is formed prior to the step of
applying the structural coating, and wherein the structural coating
does not bridge the one or more run-out regions, such that each
run-out region forms a film hole for the respective groove.
9. The repair method of claim 8, wherein a portion of the applied
structural coating is deposited in the one or more run-out regions,
the repair method further comprising removing at least a portion of
the structural coating deposited in each run-out region, such that
each run-out region forms a film hole for the respective
groove.
10. The repair method of claim 1, wherein performing the repair
operation comprises performing one or more of: repairing one or
more connecting grooves that intersect at least a subset of the one
or more re-entrant shaped grooves, wherein the applied structural
coating does not completely bridge the connecting groove(s), such
that each connecting groove at least partially defines an exit
region for the respective one or more cooling channels; repairing
one or more run-out regions adjacent to a respective discharge
point for each groove, wherein the structural coating does not
bridge the one or more run-out regions, such that each run-out
region forms a film hole for the respective groove; repairing one
or more craters, wherein each crater is in fluid connection with a
respective discharge end for each groove, and wherein the applied
structural coating does not completely bridge each of the one or
more craters, such that each crater defines a film exit for the
respective groove; repairing one or more trenches in the component,
wherein each trench at least partially defines at least one exit
region (for the one or more cooling channels; and drilling one or
more film holes through the thermal barrier coating, bond coating,
and structural coating to intersect the respective groove(s).
11. The repair method of claim 1, wherein each groove has at least
one discharge end, the repair method further comprising: forming a
run-out region adjacent to the respective discharge point for each
groove, wherein the run-out region is formed prior to the step of
applying the structural coating, and wherein a footprint of each
run-out region is narrower at the discharge point for the
respective groove and wider at an opposite end of the run-out
region, such that the run-out region forms a diffuser film
hole.
12. The repair method of claim 1, wherein the structural coating
comprises the bond coating, such that the thermal barrier coating
is disposed on the structural coating.
13. The repair method of claim 1, wherein the structural coating
and the bond coating are distinct coatings.
14. A method for repairing a component having a substrate
comprising an outer surface and an inner surface, wherein the inner
surface defines at least one hollow, interior space, wherein one or
more grooves extend at least partially along the component, the
component further comprising a structural coating disposed over at
least a portion of the outer surface of the substrate, a bond
coating disposed over the structural coating, and a thermal barrier
coating disposed over the bond coating, wherein the structural
coating comprises an inner structural coating layer disposed on the
outer surface of the substrate and an outer structural coating
layer disposed on the inner structural coating layer, wherein each
groove is formed at least partially in the inner structural coating
layer, wherein the one or more grooves and the structural coating
together define one or more channels for cooling the component, the
repair method comprising: removing the thermal barrier coating;
removing the bond coating; removing at least a portion of the outer
structural coating layer in a vicinity of a damaged portion of the
inner structural coating layer; performing a repair operation on
the damaged portion of the inner structural coating layer; applying
an outer structural coating layer over any exposed portions of the
inner structural coating layer; applying a bond coating over the
outer structural coating; and applying a thermal barrier coating
over the bond coating.
15. The repair method of claim 14, wherein each groove has a base
and a top, wherein the base of each groove is wider than the top,
such that each groove comprises a re-entrant shaped groove, wherein
the outer layer of the structural coating is applied without the
use of a sacrificial filler, such that the outer layer of the
structural coating is applied over open ones of the one or more
re-entrant shaped grooves, and wherein the applied outer layer of
the structural coating completely bridges the respective grooves,
such that the applied outer layer of the structural coating seals
the respective cooling channels.
16. The repair method of claim 14, wherein each groove has a base
and a top, wherein each of the respective one or more grooves
narrows at the respective top thereof, such that each groove
comprises a re-entrant shaped groove, wherein the outer layer of
the structural coating is applied without the use of a sacrificial
filler, such that the outer layer of the structural coating is
applied over open ones of the one or more re-entrant shaped
grooves, and wherein the applied outer layer of the structural
coating defines one or more porous gaps such that the applied outer
layer of the structural coating does not completely bridge each of
the respective grooves.
17. The repair method of claim 14, wherein the repair operation
comprises performing one or more of: machining a portion of at
least one of the one or more grooves; forming one or more
additional grooves at least partially in the inner structural
coating layer; and removing one or more grooves from the inner
structural coating layer.
18. A method for repairing a component having a substrate
comprising an outer surface and an inner surface, wherein the inner
surface defines at least one hollow, interior space, wherein the
substrate defines one or more grooves, wherein each groove extends
at least partially along the outer surface of the substrate,
wherein each groove has a base and a top, wherein each of the
respective one or more grooves narrows at the respective top
thereof, such that each groove comprises a re-entrant shaped
groove, the component further comprising a structural coating
disposed over at least a portion of the outer surface of the
substrate, a bond coating disposed over the structural coating, and
a thermal barrier coating disposed over the bond coating, wherein
the one or more re-entrant shaped grooves and the structural
coating together define one or more re-entrant shaped channels for
cooling the component, the repair method comprising: removing the
thermal barrier coating; removing the bond coating; removing at
least a portion of the structural coating in a vicinity of a
damaged portion of the component; performing a repair operation on
the damaged portion of the component; applying a structural coating
at least in a vicinity of the repaired portion of the component;
applying a bond coating over the structural coating; and applying a
thermal bather coating over the bond coating.
19. The repair method of claim 18, wherein the entire structural
coating is removed, and wherein the structural coating is applied
globally over the substrate after the repair operation has been
performed.
20. The repair method of claim 18, wherein the structural coating
is applied without the use of a sacrificial filler, such that the
structural coating is applied over open ones of the one or more
re-entrant shaped grooves.
21. The repair method of claim 18, wherein the repair operation
comprises performing one or more of: machining a portion of at
least one of the one or more re-entrant shaped grooves; forming one
or more additional grooves in the substrate; and removing one or
more grooves from the substrate.
22. The repair method of claim 18, wherein each groove has at least
one discharge end, the repair method further comprising: forming a
run-out region adjacent to the respective discharge point for each
re-entrant shaped groove, wherein the run-out region is formed
prior to the step of applying the structural coating, and wherein
the applied structural coating does not bridge the one or more
run-out regions, such that each run-out region forms a film hole
for the respective re-entrant shaped groove.
23. The repair method of claim 18, wherein each groove has at least
one discharge end, the repair method further comprising: forming a
run-out region adjacent to the respective discharge point for each
re-entrant shaped groove, wherein the run-out region is formed
prior to the step of applying the structural coating, wherein a
portion of the applied structural coating is deposited in the one
or more run-out regions; and removing at least a portion of the
applied structural coating deposited in each run-out region, such
that each run-out region forms a film hole for the respective
re-entrant shaped groove.
24. The repair method of claim 18, wherein each re-entrant shaped
groove has at least one discharge end, the repair method further
comprising: forming a run-out region adjacent to the respective
discharge point for each re-entrant shaped groove, wherein the
run-out region is formed prior to the step of applying the
structural coating, and wherein a footprint of each run-out region
is narrower at the discharge point for the respective re-entrant
shaped groove and wider at an opposite end of the run-out region,
such that the run-out region forms a diffuser film hole.
25. The repair method of claim 18, wherein each groove has at least
one discharge end, the repair method further comprising forming a
crater prior to the step of applying the structural coating, such
that the crater is in fluid connection with the respective
discharge end for each groove, wherein the applied structural
coating does not completely bridge each of the one or more craters,
such that each crater defines a film exit.
26. The repair method of claim 25, wherein a portion of the applied
structural coating is deposited in the one or more craters, the
repair method further comprising removing at least some of the
applied structural coating deposited in each crater to form the
film hole for the respective channel.
27. The repair method of claim 18 further comprising repairing at
least one connecting groove in the component, such that each
connecting groove intersects at least a subset of the one or more
re-entrant shaped grooves, wherein the connecting groove is
repaired prior to the step of applying the structural coating, and
wherein the applied structural coating does not completely bridge
the connecting groove, such that the connecting groove at least
partially defines an exit region for the respective one or more
re-entrant shaped cooling channels.
28. The repair method of claim 27, wherein each of the one or more
connecting grooves is open-shaped, and wherein a portion of the
applied structural coating is disposed in the exit region of
respective connecting grooves, the repair method further comprising
removing at least a portion of the applied structural coating
disposed in each exit region.
29. The repair method of claim 18 further comprising forming at
least one or more trenches in the component to at least partially
define at least one exit region for the one or more cooling
channels.
30. The repair method of claim 18, wherein performing the repair
operation comprises performing one or more of: repairing one or
more connecting grooves that intersect at least a subset of the one
or more re-entrant shaped grooves, wherein the applied structural
coating does not completely bridge the connecting groove(s), such
that each connecting groove at least partially defines an exit
region for the respective one or more re-entrant shaped cooling
channels; repairing one or more run-out regions adjacent to a
respective discharge point for each groove, wherein the structural
coating does not bridge the one or more run-out regions, such that
each run-out region forms a film hole for the respective re-entrant
shaped groove; repairing one or more craters, wherein each crater
is in fluid connection with a respective discharge end for each
groove, and wherein the locally applied structural coating does not
completely bridge each of the one or more craters, such that each
crater defines a film exit for the respective re-entrant shaped
groove; repairing one or more trenches in the component, wherein
each trench at least partially defines at least one exit region for
the one or more re-entrant shaped cooling channels; and drilling
one or more film holes through the thermal barrier coating, bond
coating, and structural coating to intersect the respective
groove(s).
31. The repair method of claim 18, wherein the structural coating
comprises the bond coating, such that the thermal barrier coating
is disposed on the structural coating.
32. The repair method of claim 18, wherein the structural coating
and the bond coating are distinct coatings.
33. A method for repairing a component having a substrate
comprising an outer surface and an inner surface, wherein the inner
surface defines at least one hollow, interior space, the component
further comprising a structural coating disposed over at least a
portion of the outer surface of the substrate, a bond coating
disposed over the structural coating, and a thermal barrier coating
disposed over the bond coating, the repair method comprising:
removing the thermal barrier coating; removing the bond coating;
removing at least a portion of the structural coating in a vicinity
of a damaged portion of the component; forming one or more grooves
in the substrate, wherein each groove extends at least partially
along the outer surface of the substrate; applying a structural
coating at least in a vicinity of the repaired portion of the
component, wherein the one or more grooves and the applied
structural coating together define one or more channels for cooling
the component; applying a bond coating over the structural coating;
and applying a thermal barrier coating over the bond coating.
34. The method for repairing a component of claim 33, further
comprising performing a repair operation on the damaged portion of
the component after removing at least the portion of the structural
coating and prior to applying the structural coating.
35. The method for repairing a component of claim 34, wherein each
groove has a base and a top, and wherein each of the respective one
or more grooves narrows at the respective top thereof, such that
each groove comprises a re-entrant shaped groove.
Description
BACKGROUND
[0001] The invention relates generally to gas turbine engines, and,
more specifically, to repair methods for cooled components.
[0002] In a gas turbine engine, air is pressurized in a compressor
and mixed with fuel in a combustor for generating hot combustion
gases. Energy is extracted from the gases in a high pressure
turbine (HPT), which powers the compressor, and in a low pressure
turbine (LPT), which powers a fan in a turbofan aircraft engine
application, or powers an external shaft for marine and industrial
applications.
[0003] Engine efficiency increases with temperature of combustion
gases. However, the combustion gases heat the various components
along their flowpath, which in turn requires cooling thereof to
achieve a long engine lifetime. Typically, the hot gas path
components are cooled by bleeding air from the compressor. This
cooling process reduces engine efficiency, as the bled air is not
used in the combustion process.
[0004] Gas turbine engine cooling art is mature and includes
numerous patents for various aspects of cooling circuits and
features in the various hot gas path components. For example, the
combustor includes radially outer and inner liners, which require
cooling during operation. Turbine nozzles include hollow vanes
supported between outer and inner bands, which also require
cooling. Turbine rotor blades are hollow and typically include
cooling circuits therein, with the blades being surrounded by
turbine shrouds, which also require cooling. The hot combustion
gases are discharged through an exhaust which may also be lined,
and suitably cooled.
[0005] In all of these exemplary gas turbine engine components,
thin metal walls of high strength superalloy metals are typically
used for enhanced durability while minimizing the need for cooling
thereof. Various cooling circuits and features are tailored for
these individual components in their corresponding environments in
the engine. For example, a series of internal cooling passages, or
serpentines, may be formed in a hot gas path component. A cooling
fluid may be provided to the serpentines from a plenum, and the
cooling fluid may flow through the passages, cooling the hot gas
path component substrate and coatings. However, this cooling
strategy typically results in comparatively low heat transfer rates
and non-uniform component temperature profiles.
[0006] Micro-channel cooling has the potential to significantly
reduce cooling requirements by placing the cooling as close as
possible to the heated region, thus reducing the temperature
difference between the hot side and cold side of the main load
bearing substrate material for a given heat transfer rate.
[0007] As cooled turbine components are exposed to severe
conditions during engine operation, they may crack or suffer other
distress, such as burning. Repair operations may therefore be
required. Repair processes for conventionally cooled components can
be time consuming and costly and would not be directly applicable
to micro-channel cooled components.
[0008] It would therefore be desirable to develop repair processes
suitable for repairing micro-channel cooled components. It would
further be desirable to develop repair processes to add
micro-channel cooling to modify the cooling scheme for
conventionally cooled components, in order to alleviate local,
thermal distress within the components.
BRIEF DESCRIPTION
[0009] One aspect of the present invention resides in a method for
repairing a component having a substrate comprising an outer
surface and an inner surface, where the inner surface defines at
least one hollow, interior space. The substrate defines one or more
grooves, where each groove extends at least partially along the
outer surface of the substrate. The component further comprises a
structural coating disposed over at least a portion of the outer
surface of the substrate, a bond coating disposed over the
structural coating, and a thermal bather coating disposed over the
bond coating. The groove(s) and the structural coating together
define one or more channels for cooling the component. The repair
method includes removing the thermal bather coating, removing the
bond coating, removing at least a portion of the structural coating
in a vicinity of a damaged portion of the component, and performing
a repair operation on the damaged portion of the component. The
repair method further includes applying a structural coating at
least in a vicinity of the repaired portion of the component,
applying a bond coating over the structural coating, and applying a
thermal bather coating over the bond coating.
[0010] Another aspect of the invention resides in a method for
repairing a component having a substrate comprising an outer
surface and an inner surface, where the inner surface defines at
least one hollow, interior space. One or more grooves extend at
least partially along the component. The component further
comprises a structural coating disposed over at least a portion of
the outer surface of the substrate, a bond coating disposed over
the structural coating, and a thermal bather coating disposed over
the bond coating. The structural coating comprises an inner
structural coating layer disposed on the outer surface of the
substrate and an outer structural coating layer disposed on the
inner structural coating layer. Each groove is formed at least
partially in the inner structural coating layer. The groove(s) and
the structural coating together define one or more channels for
cooling the component. The repair method includes removing the
thermal bather coating, removing the bond coating, removing at
least a portion of the outer structural coating layer in a vicinity
of a damaged portion of the inner structural coating layer, and
performing a repair operation on the damaged portion of the inner
structural coating layer. The repair method further includes
applying an outer structural coating layer over any exposed
portions of the inner structural coating layer, applying a bond
coating over the outer structural coating, and applying a thermal
barrier coating over the bond coating.
[0011] Yet another aspect of the present invention resides in a
method for repairing a component having a substrate comprising an
outer surface and an inner surface. The inner surface defines at
least one hollow, interior space, and the substrate defines one or
more grooves. Each groove extends at least partially along the
outer surface of the substrate and has a base and a top. Each
groove narrows at the respective top thereof, such that each groove
comprises a re-entrant shaped groove. The component further
comprises a structural coating disposed over at least a portion of
the outer surface of the substrate, a bond coating disposed over
the structural coating, and a thermal barrier coating disposed over
the bond coating. The re-entrant shaped groove(s) and the
structural coating together define one or more re-entrant shaped
channels for cooling the component. The repair method includes
removing the thermal barrier coating, removing the bond coating,
removing at least a portion of the structural coating in a vicinity
of a damaged portion of the component, and performing a repair
operation on the damaged portion of the component. The repair
method further includes applying a structural coating at least in a
vicinity of the repaired portion of the component, applying a bond
coating over the structural coating, and applying a thermal barrier
coating over the bond coating.
[0012] Still another aspect of the present invention resides in a
method for repairing a component having a substrate comprising an
outer surface and an inner surface, where the inner surface defines
at least one hollow, interior space. The component further
comprises a structural coating disposed over at least a portion of
the outer surface of the substrate, a bond coating disposed over
the structural coating, and a thermal barrier coating disposed over
the bond coating. The repair method includes removing the thermal
barrier coating, removing the bond coating, and removing at least a
portion of the structural coating in a vicinity of a damaged
portion of the component. The method further includes forming one
or more grooves in the substrate, applying a structural coating at
least in a vicinity of the repaired portion of the component,
applying a bond coating over the structural coating, and applying a
thermal bather coating over the bond coating. Each groove extends
at least partially along the outer surface of the substrate, and
the groove(s) and the structural coating together define one or
more channels for cooling the component.
DRAWINGS
[0013] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0014] FIG. 1 is a schematic illustration of a gas turbine
system;
[0015] FIG. 2 is a schematic cross-section of an example airfoil
configuration with cooling channels, in accordance with aspects of
the present invention;
[0016] FIG. 3 schematically depicts, in perspective view, three
example open shaped cooling grooves that extend partially along the
surface of the substrate, where the substrate is covered by a
structural coating, a bond coat, and a thermal barrier coating;
[0017] FIG. 4 schematically depicts, in perspective view, the
cooling grooves of FIG. 3, where the thermal barrier coating has
been removed;
[0018] FIG. 5 schematically depicts, in perspective view, the
cooling grooves of FIG. 4, where the bond coat has also been
removed;
[0019] FIG. 6 schematically depicts the local removal of a portion
of the structural coating in the vicinity of a damaged portion of
the substrate near an open shaped groove;
[0020] FIG. 7 schematically depicts the local application of a
portion of the structural coating in the vicinity of a repaired
portion of the substrate, for a re-entrant shaped channel;
[0021] FIG. 8 depicts the formation of an example crater in the
substrate;
[0022] FIG. 9 depicts the formation of example run-out regions in
the substrate;
[0023] FIG. 10 shows an example cooling channel and run-out region
with a structural coating applied;
[0024] FIG. 11 shows the example cooling channel of FIG. 10 with a
film hole formed in the run-out region by removal of a portion of
the coating in the run-out region;
[0025] FIG. 12 is a top view of an example diffuser-shaped run-out
region, which is wider than the respective groove;
[0026] FIG. 13 schematically depicts three re-entrant shaped
cooling channels formed in an inner structural coating layer;
[0027] FIG. 14 shows the re-entrant shaped grooves of FIG. 13 with
the thermal barrier coating, bond coat, and the outer layer of the
structural coating removed;
[0028] FIG. 15 schematically depicts, in perspective view, three
example re-entrant shaped cooling grooves that extend partially
along the surface of the substrate and channel coolant to an exit
region formed by a connecting groove;
[0029] FIG. 16 is a cross-sectional view of one of the example
cooling channels of FIG. 15 and shows the channel conveying coolant
from an access hole to an exit region formed by a connecting
groove;
[0030] FIG. 17 schematically depicts, in perspective view, three
example cooling channels that extend partially along the surface of
the substrate and channel coolant to respective exit regions formed
in a trench in the coating; and
[0031] FIG. 18 is a cross-sectional view of one of the example
cooling channels of FIG. 17 and shows the channel conveying coolant
from an access hole to an exit region formed in a trench in the
coating.
DETAILED DESCRIPTION
[0032] The terms "first," "second," and the like, herein do not
denote any order, quantity, or importance, but rather are used to
distinguish one element from another. The terms "a" and "an" herein
do not denote a limitation of quantity, but rather denote the
presence of at least one of the referenced items. The modifier
"about" used in connection with a quantity is inclusive of the
stated value, and has the meaning dictated by context, (e.g.,
includes the degree of error associated with measurement of the
particular quantity). In addition, the term "combination" is
inclusive of blends, mixtures, alloys, reaction products, and the
like.
[0033] Moreover, in this specification, the suffix "(s)" is usually
intended to include both the singular and the plural of the term
that it modifies, thereby including one or more of that term (e.g.,
"the passage hole" may include one or more passage holes, unless
otherwise specified). Reference throughout the specification to
"one embodiment," "another embodiment," "an embodiment," and so
forth, means that a particular element (e.g., feature, structure,
and/or characteristic) described in connection with the embodiment
is included in at least one embodiment described herein, and may or
may not be present in other embodiments. Similarly, reference to "a
particular configuration" means that a particular element (e.g.,
feature, structure, and/or characteristic) described in connection
with the configuration is included in at least one configuration
described herein, and may or may not be present in other
configurations. In addition, it is to be understood that the
described inventive features may be combined in any suitable manner
in the various embodiments and configurations.
[0034] FIG. 1 is a schematic diagram of a gas turbine system 10.
The system 10 may include one or more compressors 12, combustors
14, turbines 16, and fuel nozzles 20. The compressor 12 and turbine
16 may be coupled by one or more shaft 18. The shaft 18 may be a
single shaft or multiple shaft segments coupled together to form
shaft 18.
[0035] The gas turbine system 10 may include a number of hot gas
path components 100. A hot gas path component is any component of
the system 10 that is at least partially exposed to a high
temperature flow of gas through the system 10. For example, bucket
assemblies (also known as blades or blade assemblies), nozzle
assemblies (also known as vanes or vane assemblies), shroud
assemblies, transition pieces, retaining rings, and compressor
exhaust components are all hot gas path components. However, it
should be understood that the hot gas path component 100 of the
present invention is not limited to the above examples, but may be
any component that is at least partially exposed to a high
temperature flow of gas. Further, it should be understood that the
hot gas path component 100 of the present disclosure is not limited
to components in gas turbine systems 10, but may be any piece of
machinery or component thereof that may be exposed to high
temperature flows.
[0036] When a hot gas path component 100 is exposed to a hot gas
flow 80, the hot gas path component 100 is heated by the hot gas
flow 80 and may reach a temperature at which the hot gas path
component 100 fails. Thus, in order to allow system 10 to operate
with hot gas flow 80 at a high temperature, increasing the
efficiency and performance of the system 10, a cooling system for
the hot gas path component 100 is required.
[0037] In general, the cooling system of the present disclosure
includes a series of small channels, or micro-channels, formed in
the surface of the hot gas path component 100. For industrial sized
power generating turbine components, "small" or "micro" channel
dimensions would encompass approximate depths and widths in the
range of 0.25 mm to 1.5 mm, while for aviation sized turbine
components channel dimensions would encompass approximate depths
and widths in the range of 0.15 mm to 0.5 mm. The hot gas path
component may be provided with a cover layer. A cooling fluid may
be provided to the channels from a plenum, and the cooling fluid
may flow through the channels, cooling the cover layer.
[0038] A method for repairing a component 100 is described with
reference to FIGS. 2-12. As indicated in FIG. 2, for example, the
component 100 has a substrate 110 comprising an outer surface 112
and an inner surface 116, where the inner surface 116 defines at
least one hollow, interior space 114. As indicated, for example, in
FIGS. 2-5, the substrate 110 defines one or more grooves 132, where
each groove 132 extends at least partially along the outer surface
of the substrate 110. As indicated, for example, in FIGS. 3-5, the
component 100 further includes a structural coating 150 disposed
over at least a portion of the outer surface 112 of the substrate
110, a bond coating 152 disposed over the structural coating, and a
thermal barrier coating 154 disposed over the bond coating. As
indicated, for example, in FIG. 5, the groove(s) 132 and the
structural coating 150 together define one or more channels 130 for
cooling the component 100.
[0039] As discussed in U.S. Pat. No. 5,626,462, Melvin R. Jackson
et al., "Double-wall airfoil," which is incorporated herein in its
entirety, substrate 110 may be formed from any suitable material.
Depending on the intended application for component 100, this could
include Ni-base, Co-base and Fe-base superalloys. The Ni-base
superalloys may be those containing both .gamma. and g' phases,
particularly those Ni-base superalloys containing both g and
.gamma.' phases wherein the .gamma.' phase occupies at least 40% by
volume of the superalloy. Such alloys are known to be advantageous
because of a combination of desirable properties including high
temperature strength and high temperature creep resistance. The
substrate material may also comprise a NiAl intermetallic alloy, as
these alloys are also known to possess a combination of superior
properties including high temperature strength and high temperature
creep resistance that are advantageous for use in turbine engine
applications used for aircraft. In the case of Nb-base alloys,
coated Nb-base alloys having superior oxidation resistance will be
preferred, particularly those alloys comprising
Nb-(27-40)Ti-(4.5-10.5)Al-(4.5-7.9)Cr-(1.5-5.5)Hf-(0-6)V, where the
composition ranges are in atom percent. The substrate material may
also comprise a Nb-base alloy that contains at least one secondary
phase, such as a Nb-containing intermetallic compound comprising a
silicide, carbide or boride. Such alloys are composites of a
ductile phase (i.e., the Nb-base alloy) and a strengthening phase
(i.e., a Nb-containing intermetallic compound). For other
arrangements, the substrate material comprises a molybdenum based
alloy, such as alloys based on molybdenum (solid solution) with
Mo.sub.5SiB.sub.2 and Mo.sub.3Si second phases. For other
configurations, the substrate material comprises a ceramic matrix
composite, such as a silicon carbide (SiC) matrix reinforced with
SiC fibers. For other configurations the substrate material
comprises a TiAl-based intermetallic compound.
[0040] For particular configurations, the structural coating 150
has a thickness in the range of 0.1-2.0 millimeters, and more
particularly, in the range of 0.1 to 1 millimeter, and still more
particularly 0.1 to 0.5 millimeters for industrial components. For
aviation components, this range is typically 0.1 to 0.25
millimeters. However, other thicknesses may be utilized depending
on the requirements for a particular component 100. For certain hot
gas path components 100, the structural coating 150 comprises a
nickel-based or cobalt-based alloy, and more particularly comprises
a superalloy or a (NiCo)CrAlY alloy. For example, where the
substrate material is a Ni-base superalloy containing both .gamma.
and .gamma.' phases, structural coating may comprise similar
compositions of materials, as discussed in U.S. Pat. No.
5,626,462.
[0041] Referring now to FIGS. 3 and 4, the repair method comprises
removing the thermal barrier coating 154. For example, the thermal
barrier coating may be removed mechanically, for example by grit
blasting. As indicated in FIGS. 4 and 5, the repair method further
comprises removing the bond coating 152. For example, the bond
coating may be removed chemically. As indicated, for example, in
FIG. 6, the repair method further includes removing at least a
portion of the structural coating 150 in a vicinity of a damaged
portion 111 of the component and performing a repair operation on
the damaged portion 111 of the component 110. For the illustrated
example shown in FIG. 6, the structural coating 150 is locally
removed. However, for other process configurations, the structural
coating 150 may be globally removed. For example, any cracks 113 in
the substrate may be repaired using a braze material or by
performing laser consolidation. The repair operation may encompass
repairing a damaged portion of the substrate, coating, or both the
coating and the substrate. It should be noted that for certain
configurations (not shown), the structural coating 150 comprises
the bond coating 152, such that the thermal barrier coating is
disposed on the structural coating 150. However, for the
illustrated arrangements, the structural coating 150 and the bond
coating 152 are distinct coatings.
[0042] As indicated in FIG. 7, the repair method further comprises
applying a structural coating 150 at least in a vicinity of the
repaired portion 111 of the substrate 110. For the example
illustrated by FIG. 7, the structural coating is locally applied in
the vicinity of the repaired portion 111 of the substrate 110.
However, for other process configurations, the structural coating
150 may be globally applied to the substrate 110. The repair method
further comprises applying a bond coating 152 (FIG. 4) over the
structural coating 150 and applying a thermal barrier coating 154
(FIG. 3) over the bond coating 152. The coating layer(s) may be
deposited using a variety of techniques. For particular processes,
the structural coating layer(s) are deposited by performing an ion
plasma deposition (cathodic arc). Example ion plasma deposition
apparatus and method are provided in commonly assigned, US
Published Patent Application No. 10080138529, Weaver et al, "Method
and apparatus for cathodic arc ion plasma deposition," which is
incorporated by reference herein in its entirety. Briefly, ion
plasma deposition comprises placing a cathode formed of a coating
material into a vacuum environment within a vacuum chamber,
providing a substrate 110 within the vacuum environment, supplying
a current to the cathode to form a cathodic arc upon a cathode
surface resulting in arc-induced erosion of coating material from
the cathode surface, and depositing the coating material from the
cathode upon the substrate surface 112.
[0043] Non-limiting examples of a coating deposited using ion
plasma deposition include structural coatings, as well as bond
coatings and oxidation-resistant coatings, as discussed in greater
detail below with reference to U.S. Pat. No. 5,626,462, Jackson et
al., "Double-wall airfoil." For certain hot gas path components
100, the structural coating comprises a nickel-based or
cobalt-based alloy, and more particularly comprises a superalloy or
a (NiCo)CrAlY alloy.
[0044] For other process configurations, the structural coating is
deposited by performing at least one of a thermal spray process and
a cold spray process. For example, the thermal spray process may
comprise combustion spraying or plasma spraying, the combustion
spraying may comprise high velocity oxygen fuel spraying (HVOF) or
high velocity air fuel spraying (HVAF), and the plasma spraying may
comprise atmospheric (such as air or inert gas) plasma spray, or
low pressure plasma spray (LPPS, which is also known as vacuum
plasma spray or VPS). In one non-limiting example, a NiCrAlY
coating is deposited by HVOF or HVAF. Other example techniques for
depositing the structural coating include, without limitation,
sputtering, electron beam physical vapor deposition, electroless
plating, and electroplating.
[0045] For certain configurations, it is desirable to employ
multiple deposition techniques for depositing structural and
optional additional coating layers. For example, a first structural
coating layer may be deposited using an ion plasma deposition, and
a subsequently deposited layer and optional additional layers (not
shown) may be deposited using other techniques, such as a
combustion spray process or a plasma spray process. Depending on
the materials used, the use of different deposition techniques for
the coating layers may provide benefits in properties, such as, but
not restricted to strain tolerance, strength, adhesion, and/or
ductility.
[0046] For the configuration shown in FIG. 7, each groove 132 has a
base 134 and a top 136. Each groove 132 narrows at the respective
top 136 thereof, such that each groove 132 comprises a re-entrant
shaped groove 132. For the illustrated arrangements, the base 134
of each groove is wider than the top 136. For particular
configurations, the base 134 of each re-entrant shaped groove 132
is at least two times wider than the top 136 of the respective
groove 132. For more particular configurations, the base 134 is in
a range of about 3-4 times wider than the top 136 of the respective
groove 132. Example re-entrant shaped grooves 132 are shown in FIG.
7. The formation of re-entrant shaped cooling channels 130 is
described in commonly assigned U.S. patent application Ser. No.
12/943,624, Ronald S. Bunker et al., "Components with re-entrant
shaped cooling channels and methods of manufacture," which is
incorporated herein in its entirety.
[0047] For particular processes, the structural coating 150 is
applied without the use of a sacrificial filler, such that the
structural coating 150 is applied over open ones of the one or more
grooves 132. For particular processes, the structural coating 150
completely bridges the respective grooves 132, such that the
structural coating 150 seals the respective cooling channels 130.
In FIG. 7, the applied structural coating completely bridges the
groove on the left hand side. However, for other processes, the
structural coating 150 defines one or more porous gaps 144, such
that the structural coating 150 does not completely bridge each of
the respective grooves 132. Although, in FIG. 7, the structural
coating completely bridges the groove on the left hand side, porous
gaps 144 are shown for the two grooves on the right in FIG. 7.
[0048] The repair operation may encompass one or more machining
operations and be performed using a variety of techniques. For
particular processes, the repair operation includes locally
machining a portion of at least one of the one or more grooves 132.
for example, the local machining operation may be performed using
one or more of an abrasive liquid jet, plunge electrochemical
machining (ECM), electric discharge machining (EDM) with a spinning
electrode (milling EDM) and laser machining. For other processes,
the repair operation may include forming one or more additional
grooves 132 in the substrate 110 or removing one or more grooves
132 from the substrate 110. Grooves may be removed, for example, by
braze fill or weld filling them closed, or by laser consolidation
to fill. Beneficially, by adding grooves to a component within a
distressed region, cooling may be improved within that region of
the component. grooves are
[0049] For the example arrangement illustrated by FIG. 8, each
groove 132 has at least one discharge end 170. For particular
processes, the repair method further includes forming a crater 180
prior to the step of applying the structural coating 150, such that
the crater 180 is in fluid connection with the respective discharge
end 170 for each groove 132. More particularly, the structural
coating 150 does not completely bridge each of the one or more
craters 180, such that each crater 180 defines a film exit 174.
Although the film exit 174 is not shown in FIG. 8, an example film
exit 174 is shown in FIG. 11 for another configuration. The
formation of film exits in micro-channel cooled components using
craters is discussed in commonly assigned U.S. patent application
Ser. No. 13/168,144, Ronald S. Bunker, "Components with cooling
channels and methods of manufacture," which is incorporated herein
in its entirety. For particular processes, each crater 180 may be
formed by directing an abrasive liquid jet at the outer surface 112
of the substrate 110. An example crater is shown in FIG. 8. For
more particular processes, a portion of the structural coating 150
is deposited in the one or more craters 180, and the repair method
further includes removing at least some of the structural coating
150 deposited in each crater to form the film hole 174 for the
respective channel 130. Although this additional process step is
not expressly shown, it is similar to the step illustrated by FIGS.
10 and 11.
[0050] For the configuration shown in FIG. 9, each groove 132 has
at least one discharge end 170, and the repair method further
includes forming a run-out region 172 adjacent to the respective
discharge point 170 for each groove 132. The run-out region 172 is
formed prior to the step of locally applying the structural coating
150. For more particular processes, the structural coating 150 does
not bridge the run-out region(s) 172, such that each run-out region
172 forms a film hole 174 for the respective groove 132. The
formation of film exits in micro-channel cooled components using
run-out regions is discussed in commonly assigned U.S. patent
application Ser. No. 13/026,595, Ronald S. Bunker, "Components with
cooling channels and methods of manufacture," which is incorporated
herein in its entirety. For example processes, each run-out region
172 may be formed using an abrasive liquid jet (not shown). For
particular applications, each run-out region 172 is formed by
lifting the abrasive liquid jet from the outer surface 112 of the
substrate 110, such that each run-out region 172 is tapered. For
certain configurations, the run-out region 172 is wider than the
respective groove 132.
[0051] For the particular process illustrated by FIGS. 10 and 11, a
portion of the structural coating 150 is deposited in the run-out
region(s) 172, as indicated in FIG. 10. As shown in FIG. 11, the
repair method further optionally includes removing at least a
portion of the structural coating 150 deposited in each run-out
region, such that each run-out region 172 forms a film hole 174 for
the respective groove 132.
[0052] For the configuration shown in FIG. 12, each groove 132 has
at least one discharge end 170, and the repair method further
includes forming a run-out region 172 adjacent to the respective
discharge point 170 for each groove 132, where the run-out region
is formed prior to the step of applying the structural coating 150.
For the particular configuration shown in FIG. 12, the footprint
176 of each run-out region 172 is narrower at the discharge point
170 for the respective groove 132 and wider at an opposite end 178
of the run-out region 172, such that the run-out region 172 forms a
diffuser film hole 174.
[0053] In addition to forming run-out regions or craters, repairing
cracks, and adding or removing grooves, the repair operation may
optionally include one or more of: drilling one or more film holes
174 through the thermal barrier coating 154, bond coating 152, and
structural coating 150 to intersect the respective groove(s) 132,
repairing one or more connecting grooves 232 (which are described
below with reference to FIGS. 15 and 16), repairing one or more
run-out regions 172 or craters 180, and repairing one or more
trenches 60 (which are described below with reference to FIGS. 17
and 18). Beneficially, by using run-out regions, craters and/or
trenches, the repair of conventional film holes (which typically
requires either repairing the film holes or relocating the film
holes for drilling) is simplified. In addition, for parts with an
ion plasma (IPD) structural coating, only the bondcoat and TBC need
be stripped off. The IPD coating need not be removed unless a
region has extensive damage. In addition, for certain processes,
this may apply to thermal spray coatings as well.
[0054] Another method for repairing a component 100 is described
with reference to FIGS. 2-7 and 13. As described above with
reference to FIG. 2, the component 100 has a substrate 110
comprising an outer surface 112 and an inner surface 116. The inner
surface 116 defines at least one hollow, interior space 114. As
described above with reference to FIGS. 2-5, one or more grooves
132 extend at least partially along the component 100. As described
above with reference to FIGS. 3-5, the component further includes a
structural coating 150 disposed over at least a portion of the
outer surface 112 of the substrate 110, a bond coating 152 disposed
over the structural coating 150, and a thermal barrier coating 154
disposed over the bond coating 152. As indicated, for example, in
FIG. 13, the structural coating 150 comprises an inner structural
coating layer 54 disposed on the outer surface 112 of the substrate
110 and an outer structural coating layer 56 disposed on the inner
structural coating layer 54. Each groove 132 is formed at least
partially in the inner structural coating layer 54. This
arrangement is illustrated, for example, in FIG. 13. For the
arrangement shown in FIG. 13, the grooves 132 are formed entirely
in the inner structural coating layer 54. However, for other
arrangements, not shown, the grooves may extend through the inner
structural coating layer 54 into the substrate 110. For the
configuration shown in FIG. 3, the grooves 132 are formed in the
substrate. The groove(s) 132 and the structural coating 150
together define one or more channels 130 for cooling the component
100.
[0055] Similar to the process steps described above with reference
to FIGS. 3-6, the repair method comprises removing the thermal
barrier coating 154, removing the bond coating 152, and removing at
least a portion of the outer structural coating layer 56 in a
vicinity of a damaged portion 111 of the inner structural coating
layer 54. Depending on the extent of the damage, the outer
structural coating layer 56 may be locally or entirely removed.
Similar to the process step described above with reference to FIG.
6, the repair method further comprises performing a repair
operation on the damaged portion 111 of the inner structural
coating layer 54. For example, any damage to the inner structural
coating layer 54 may be repaired using a braze material or by
performing laser consolidation, or by locally applying the same
coating. The repair operation may include locally machining a
portion of at least one of the groove(s) 132, as discussed above.
Other example repair operations include forming one or more
additional grooves 132 at least partially in the inner structural
coating layer 54 and/or removing one or more grooves 132 from the
inner structural coating layer 54. Grooves may be removed for
example, by braze fill or weld filling them closed, or by laser
consolidation to fill, as well as by applying the coating and not
reforming the groove.
[0056] Similar to the process step described above with reference
to FIG. 7, the repair method further comprises applying an outer
structural coating layer 56 over any exposed portions of the inner
structural coating layer 54. If only a portion of the outer
structural coating 56 was removed, then the remaining outer
structural coating 56 may be covered with a mask (not shown), such
that the outer structural coating 56 is only locally applied over
the repaired portion of the inner layer of the structural coating
54. Similar to the process described above, the repair method
further comprises applying a bond coating 152 over the outer
structural coating 56, and applying a thermal barrier coating 154
over the bond coating 152.
[0057] For the particular arrangement shown in FIG. 13, each groove
132 has a base 134 and a top 136, each groove 132 narrows at the
respective top 136 thereof, such that each groove 132 comprises a
re-entrant shaped groove 132. For the illustrated arrangements, the
base 134 of each groove is wider than the top 136. Re-entrant
grooves are described above. For particular processes, the outer
layer of the structural coating 56 is applied without the use of a
sacrificial filler, such that the outer layer of the structural
coating 56 is applied over open ones of the re-entrant shaped
groove(s) 132. More particularly, the applied outer layer of the
structural coating 56 completely bridges the respective grooves
132, such that the applied outer layer of the structural coating 56
seals the respective cooling channels 130. For the arrangement
shown in FIG. 13, the outer layer of the structural coating 56
completely bridges the grooves 132. For other processes, the outer
layer of the structural coating 56 is applied without the use of a
sacrificial filler, and the applied outer layer of the structural
coating 56 defines one or more porous gaps 144, such that the
applied outer layer of the structural coating 56 does not
completely bridge each of the respective grooves 132. Example
porous grooves 144 are shown in FIG. 7 for the case of channels
formed in the substrate. For the present configuration, the gaps
144 shown in FIG. 7 would extend through the outer layer 56 into
the grooves 132 formed in the inner layer 54.
[0058] Another method for repairing a component 100 is described
with reference to FIGS. 2-12 and 15-18. As described above with
reference to FIG. 2, the component 100 includes a substrate 110
comprising an outer surface 112 and an inner surface 116, where the
inner surface 116 defines at least one hollow, interior space 114.
As indicated in FIG. 7, the substrate 110 defines one or more
grooves 132, and each groove 132 extends at least partially along
the outer surface of the substrate 110. As indicated in FIG. 7,
each groove 132 has a base 134 and a top 136, and each groove 132
narrows at the respective top 136 thereof, such that each groove
132 comprises a re-entrant shaped groove 132. For the illustrated
arrangements, the base 134 of each groove is wider than the top
136. Re-entrant shaped grooves are described above. As described
above with reference to FIGS. 3-5, the component 100 further
includes a structural coating 150 disposed over at least a portion
of the outer surface 112 of the substrate 110, a bond coating 152
disposed over the structural coating 150, and a thermal barrier
coating 154 disposed over the bond coating 152. As shown in FIG. 7,
the re-entrant shaped groove(s) 132 and the structural coating 150
together define one or more re-entrant shaped channels 130 for
cooling the component 100. Similar to the process steps described
above with reference to FIGS. 3-6, the repair method comprises
removing the thermal barrier coating 154, removing the bond coating
152, and removing at least a portion of the structural coating 150
in a vicinity of a damaged portion 111 of the component. Depending
on the extent of the damage, the structural coating may be locally
or entirely removed.
[0059] Similar to the process described above with reference to
FIGS. 6 and 7, the repair method further includes performing a
repair operation on the damaged portion 111 of the component 110,
for example, machining a portion of at least one of the one or more
re-entrant shaped grooves 132. Other example repair operations
include forming one or more additional grooves 132 in the substrate
110 and/or removing one or more grooves 132 from the substrate 110.
Beneficially, by adding grooves to a component within a distressed
region, cooling may be improved within that region of the
component.
[0060] The repair method further includes applying a structural
coating 150 at least in a vicinity of the repaired portion 111 of
the component. For particular processes, the structural coating 150
is applied (locally or globally) without the use of a sacrificial
filler, such that the structural coating 150 is applied over open
ones of the one or more re-entrant shaped grooves 132. This is
facilitated by the relatively narrow openings of the re-entrant
shaped grooves. Similar to the process steps described above, the
repair method further includes applying a bond coating 152 over the
structural coating 150, and applying a thermal barrier coating 154
over the bond coating 152.
[0061] For particular embodiments, the entire structural coating
150 is removed. It should be noted that the entire bond coating 152
and thermal barrier coating 154 are also removed. For these
embodiments, after the repair operation has been performed, the
structural coating 150 is applied globally over the substrate 110.
Similarly, the bond coating 152 and thermal barrier coating 154 are
also applied globally over the structural coating and bond coating
respectively.
[0062] For the configuration shown in FIG. 9, each groove 132 has
at least one discharge end 170, and the repair method further
includes forming a run-out region 172 adjacent to the respective
discharge point 170 for each re-entrant shaped groove 132. The
run-out region(s) is (are) formed prior to the step of applying the
structural coating 150. For particular processes, the applied
structural coating 150 does not bridge the run-out region(s) 172,
such that each run-out region 172 forms a film hole 174 (FIG. 11)
for the respective re-entrant shaped groove 132. As noted above,
the formation of film exits in micro-channel cooled components
using run-out regions is discussed in commonly assigned U.S. patent
application Ser. No. 13/026,595, Ronald S. Bunker, "Components with
cooling channels and methods of manufacture." As was also noted
above, the run-out regions 172 may be formed using an abrasive
liquid jet (not shown). For particular applications, each run-out
region 172 is formed by lifting the abrasive liquid jet from the
outer surface 112 of the substrate 110, such that each run-out
region 172 is tapered. For certain configurations, the run-out
region 172 is wider than the respective groove 132. As discussed
above, for the particular configuration shown in FIG. 12, the
footprint 176 of each run-out region 172 is narrower at the
discharge point 170 for the respective groove 132 and wider at an
opposite end 178 of the run-out region 172, such that the run-out
region 172 forms a diffuser film hole 174.
[0063] For the particular process illustrated by FIGS. 10 and 11, a
portion of the locally applied structural coating 150 is deposited
in the run-out region(s) 172, as indicated in FIG. 10. As shown in
FIG. 11, the repair method further optionally includes removing at
least a portion of the structural coating 150 deposited in each
run-out region, such that each run-out region 172 forms a film hole
174 for the respective groove 132.
[0064] For the configuration shown in FIG. 8, each groove 132 has
at least one discharge end 170. Similar to the process described
above with reference to FIG. 8, the repair method may further
optionally include forming a crater 180 prior to the step of
locally applying the structural coating 150, such that the crater
180 is in fluid connection with the respective discharge end 170
for each groove 132. More particularly, the locally applied
structural coating 150 does not completely bridge each of the one
or more craters 180, such that each crater 180 defines a film exit
174. Although the film exit 174 is not shown in FIG. 8, an example
film exit 174 is shown in FIG. 11 for another configuration. As
noted above, the formation of film exits in micro-channel cooled
components using craters is discussed in commonly assigned U.S.
patent application Ser. No. 13/168,144, Ronald S. Bunker,
"Components with cooling channels and methods of manufacture." For
more particular processes, a portion of the locally applied
structural coating 150 is deposited in the one or more craters 180,
and the repair method further includes removing at least some of
the locally applied structural coating 150 deposited in each crater
to form the film hole 174 for the respective channel 130. Although
this additional process step is not expressly shown, it is similar
to the step illustrated by FIGS. 10 and 11.
[0065] In addition to forming craters or run-out regions, other
features may be formed during the repair method of the present
invention. For example, FIG. 15 schematically depicts, in
perspective view, three example re-entrant shaped cooling grooves
that extend partially along the surface of the substrate and
channel coolant to an exit region formed by a connecting groove.
For this arrangement, the repair method further includes repairing
at least one connecting groove 232 in the component 100, such that
each connecting groove 232 intersects at least a subset of the one
or more re-entrant shaped grooves 132, as indicated in FIG. 15, for
example. However, the connecting grooves 232 will be repaired only
if damaged. If the connecting groove is in the substrate, then at
most, it will need to be repaired. If a portion of the connecting
groove extends into the coating 150, then this portion of the
connecting groove will require re-application. For particular
processes, the connecting groove 232 is repaired prior to the step
of applying the structural coating 150, and the applied structural
coating 150 does not completely bridge the connecting groove 232,
such that the connecting groove 232 at least partially defines an
exit region 62 for the respective re-entrant shaped cooling
channel(s) 130. The formation of exit regions in micro-channel
cooled components using connecting grooves is discussed in commonly
assigned U.S. patent application Ser. No. 13/168,117, Ronald S.
Bunker, "Components with cooling channels and methods of
manufacture," which is incorporated herein in its entirety. For
particular processes, the connecting groove(s) 232 may be formed or
repaired using an abrasive liquid jet (not shown). More
particularly, the abrasive liquid jet may be used to form or repair
each connecting groove 232 to approximately the same depth as that
of the respective channel 130. As noted above, a connecting groove
232 is illustrated in FIG. 15, and FIG. 16 is a cross-sectional
view of one of the example cooling channels of FIG. 15 and shows
the channel conveying coolant from an access hole to an exit region
formed by a connecting groove.
[0066] For particular arrangements, each connecting groove 232 is
open-shaped, and a portion of the applied structural coating 150 is
disposed in the exit region 62 of respective connecting grooves
232, as indicated in FIG. 16, for example. For this arrangement,
the repair method may further optionally include removing at least
a portion of the applied structural coating 150 disposed in each
exit region 62. For certain applications, a portion of the applied
structural coating 150 remains in the one or more exit regions 62
after the removal step. For other applications, all of the applied
structural coating 150 within each exit region 62 is removed during
the removal step. For certain configurations, the groove(s) 132 and
the connecting groove(s) 232 are formed in the outer surface 112 of
the substrate 110. For other configurations, the groove(s) 132 and
the connecting groove(s) 232 are formed at least partially in an
inner structural coating 54. For certain configurations, each
connecting groove 232 is re-entrant shaped, and a permeable slot
(not shown) extends through the applied structural coating 150 in
the exit region 62 for the connecting groove 232. For these
configurations, the repair method may further include forming at
least one exit hole through the permeable slot.
[0067] The repair method may also optionally include the formation
of one or more trenches. For example, FIG. 17 schematically
depicts, in perspective view, three example cooling channels that
extend partially along the surface of the substrate and channel
coolant to respective exit regions formed in a trench in the
coating. FIG. 18 is a cross-sectional view of one of the example
cooling channels of FIG. 17 and shows the channel conveying coolant
from an access hole to an exit region formed in a trench in the
coating. For this arrangement, the repair method further includes
forming at least one or more trenches 60 in the component to at
least partially define at least one exit region 62 for the one or
more cooling channels 130. The formation of exit regions in
micro-channel cooled components using trenches is discussed in
commonly assigned U.S. patent application Ser. No. 12/965,083,
Ronald S. Bunker, "Components with cooling channels and methods of
manufacture," which is incorporated herein in its entirety. For
particular processes, the trenches 60 may be formed using one or
more of an abrasive liquid jet, plunge electrochemical machining
(ECM), electric discharge machining (EDM) with a spinning electrode
(milling EDM), laser machining, and computer numerically controlled
(CNC) milling.
[0068] In addition to the repair operations described above, each
of the embodiments described above may include one or more repair
operations to repair existing grooves, connecting grooves, craters,
trenches, and/or run-out regions, as well as drilling one or more
film holes 174 through the thermal bather coating 154, bond coating
152, and structural coating 150 to intersect the respective
groove(s) 132. For particular processes, these repairs may be
accomplished using an abrasive liquid jet. Other machining
techniques include, without limitation, plunge electrochemical
machining (ECM), electric discharge machining (EDM) with a spinning
electrode (miffing EDM), laser machining, and computer numerically
controlled (CNC) milling. In addition and as noted above, the
repairs often utilize material addition techniques, such as but not
limited to, brazing, welding, and laser consolidation
[0069] Another method for repairing a component 100 is provided.
The repair method is similar to those described above but can be
applied to conventional components (namely, those not including
micro-channels prior to repair) to add micro-channel cooling to any
distressed regions on the part. Similar to the processes described
above, the repair method includes removing the thermal bather and
bond coatings 154, 152 and removing at least a portion of the
structural coating 150 in a vicinity of a damaged portion 111 (the
distressed region) of the component. The repair method further
includes forming one or more grooves 132 in the substrate 110,
where each groove 132 extends at least partially along the outer
surface of the substrate 110. The grooves may be formed using a
variety of machining techniques, non-limiting examples of which
include, abrasive liquid jet, plunge electrochemical machining
(ECM), electric discharge machining (EDM) with a spinning electrode
(miffing EDM), laser machining, and computer numerically controlled
(CNC) milling.
[0070] The repair method further includes applying a structural
coating 150 at least in a vicinity of the repaired portion 111 of
the component, where the groove(s) 132 and the applied structural
coating 150 together define one or more channels 130 for cooling
the component 100. The repair method further includes applying a
bond coating 152 over the structural coating 150 and applying a
thermal barrier coating 154 over the bond coating 152. It should be
noted that for certain configurations (not shown), the structural
coating 150 comprises the bond coating 152, such that the thermal
barrier coating is disposed on the structural coating 150. However,
for the illustrated arrangements, the structural coating 150 and
the bond coating 152 are distinct coatings. Beneficially, by adding
grooves to a conventional component (namely, a component that does
not initially have micro-channel cooling) within a distressed
region, cooling may be improved within that region of the
component.
[0071] In addition to forming grooves, the repair method may
optionally further include performing a repair operation on the
damaged portion 111 of the component 110 after removing at least
the portion of the structural coating 150 and prior to applying the
structural coating. The optional repair operation may include one
or more of the example repair operations described above. In
addition, for particular processes, the grooves added may comprise
re-entrant shaped grooves.
[0072] Beneficially, the above-described repair processes may be
less costly and lead to lower scrap rates than conventional repair
processes for conventional (without micro-channels) components. For
example, where the damage is localized, it may not be necessary to
remove the entire structural coating to repair the component. In
addition, for re-entrant shaped grooves, many of the above
described processes reapply the structural coating without the use
of a sacrificial filler.
[0073] Although only certain features of the invention have been
illustrated and described herein, many modifications and changes
will occur to those skilled in the art. It is, therefore, to be
understood that the appended claims are intended to cover all such
modifications and changes as fall within the true spirit of the
invention.
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