U.S. patent application number 10/930506 was filed with the patent office on 2006-03-02 for method for repairing titanium alloy components.
Invention is credited to Christopher L. Cahoon, Margaret Floyd, Yiping Hu, Federico Renteria.
Application Number | 20060045785 10/930506 |
Document ID | / |
Family ID | 35943419 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060045785 |
Kind Code |
A1 |
Hu; Yiping ; et al. |
March 2, 2006 |
Method for repairing titanium alloy components
Abstract
A method for repairing a titanium alloy surface of a turbine
component includes the step of cold gas-dynamic spraying a powder
material comprising at least one titanium alloy directly on the
titanium alloy surface. The method may further include the steps of
hot isostatic pressing the cold gas-dynamic sprayed turbine
component, and performing a separate heat treating step after the
hot isostatic pressing. Thus, the cold gas-dynamic spray process
and post-spray processing can be employed to effectively repair
degraded areas on compressor turbine components.
Inventors: |
Hu; Yiping; (Greer, SC)
; Renteria; Federico; (Greenville, SC) ; Cahoon;
Christopher L.; (Mesa, AZ) ; Floyd; Margaret;
(Chandler, AZ) |
Correspondence
Address: |
HONEYWELL INTERNATIONAL INC.
101 COLUMBIA ROAD
P O BOX 2245
MORRISTOWN
NJ
07962-2245
US
|
Family ID: |
35943419 |
Appl. No.: |
10/930506 |
Filed: |
August 30, 2004 |
Current U.S.
Class: |
419/5 ;
29/889.1 |
Current CPC
Class: |
F01D 5/005 20130101;
Y10T 29/49318 20150115; C23C 24/04 20130101; B23P 6/007
20130101 |
Class at
Publication: |
419/005 ;
029/889.1 |
International
Class: |
B22F 7/04 20060101
B22F007/04 |
Claims
1. A method for repairing a titanium alloy surface of a turbine
component, the method comprising the step of: cold gas-dynamic
spraying a powder material comprising at least one titanium alloy
directly on the titanium alloy surface.
2. The method of claim 1, wherein the powder material consists of
at least one titanium alloy.
3. The method of claim 1, wherein the powder material comprises at
least one titanium alloy selected from the group consisting of near
alpha titanium alloys, alpha-plus-beta titanium alloys, and
near-beta titanium alloys.
4. The method of claim 1, wherein the powder material comprises an
alloy that is the same alloy that forms the titanium alloy
surface.
5. The method of claim 1, wherein the cold gas-dynamic spraying is
performed in an atmosphere comprising an inert gas.
6. The method of claim 5, wherein the inert gas comprises
helium.
7. The method of claim 1, further comprising the step of: heating
the turbine component at a temperature sufficiently high to
consolidate the sprayed powder material.
8. The method of claim 1, further comprising the step of:
performing a vacuum sintering on the turbine component after the
cold gas-dynamic spraying step.
9. The method of claim 1, further comprising the step of: hot
isostatic pressing the turbine component after the cold gas-dynamic
spraying step.
10. The method of claim 9, wherein the hot isostatic pressing step
is performed 2 to 4 hours at temperatures of between about 1650 and
about 1750.degree. F. and at a pressure of at least 10 ksi.
11. The method of claim 1, further comprising the step of: heat
treating the turbine component after the cold gas-dynamic spraying
step, the heat treating comprising a first heating step performed
for about one hour at a temperature between about 1725 and about
1775.degree. F., followed by a second heating step performed for
between about two and about eight hours at a temperature between
about 900 and about 1100.degree. F.
12. The method of claim 11, wherein the titanium alloy surface
being repaired comprises Ti-6Al-4V.
13. The method of claim 1, further comprising the step of: heat
treating the turbine component after the cold gas-dynamic spraying
step, the heat treating comprising a first heating step performed
for about one hour at a temperature between about 1550 and about
1650.degree. F., followed by a second heating step performed for
between about four and about eight hours at a temperature between
about 1075 and about 1125.degree. F.
14. The method of claim 13, wherein the titanium alloy surface
being repaired comprises Ti-6Al-2Sn-4Zr-6Mo.
15. The method of claim 1, further comprising the step of: heat
treating the turbine component after the cold gas-dynamic spraying
step, the heat treating comprising a first heating step performed
for about one hour at a temperature between about 1800 and about
1850.degree. F., followed by a second heating step performed for
between about four and about eight hours at a temperature between
about 1050 and about 1100.degree. F.
16. The method of claim 15, wherein the titanium alloy surface
being repaired comprises Ti-8Al-1Mo-1V.
17. The method of claim 1, wherein turbine component comprises a
compressor blade.
18. The method of claim 17, wherein the compressor blade comprises
a tip, and wherein the cold gas-dynamic spraying is performed on
the tip.
19. The method of claim 17, wherein the compressor blade comprises
a leading edge, and wherein the cold gas-dynamic spraying is
performed on the leading edge.
20. The method of claim 17, wherein the compressor blade comprises
a platform, and wherein the cold gas-dynamic spraying is performed
on the platform.
21. A method for repairing a titanium alloy surface of a turbine
component, the method comprising the steps of: cold gas-dynamic
spraying a powder material comprising at least one titanium alloy
directly on the titanium alloy surface; hot isostatic pressing the
cold gas-dynamic sprayed turbine component; and heat treating the
turbine component after the hot isostatic pressing.
22. The method of claim 21, wherein the powder material consists of
at least one titanium alloy.
23. The method of claim 21, wherein the powder material comprises
at least one titanium alloy selected from the group consisting of
near alpha titanium alloys, alpha-plus-beta titanium alloys, and
near-beta titanium alloys.
24. The method of claim 21, wherein the powder material comprises
an alloy that is the same alloy that forms the titanium alloy
surface.
25. The method of claim 21, wherein the cold gas-dynamic spraying
is performed in an atmosphere comprising an inert gas.
26. The method of claim 25, wherein the inert gas comprises
helium.
27. The method of claim 21, further comprising the step of: before
the hot isostatic pressing step, heating the turbine component at a
temperature sufficiently high to consolidate the sprayed powder
material.
28. The method of claim 21, wherein the heat treating step
comprises a first heating step performed for about one hour at a
temperature between about 1725 and about 1775.degree. F., followed
by a second heating step performed for between about two and about
eight hours at a temperature between about 900 and about
1100.degree. F.
29. The method of claim 28, wherein the titanium alloy surface
being repaired comprises Ti-6Al-4V.
30. The method of claim 21, wherein the heat treating step
comprises a first heating step performed for about one hour at a
temperature between about 1550 and about 1650.degree. F., followed
by a second heating step performed for between about four and about
eight hours at a temperature between about 1075 and about
1125.degree. F.
31. The method of claim 30, wherein the titanium alloy surface
being repaired comprises Ti-6Al-2Sn-4Zr-6Mo.
32. The method of claim 21, wherein the heat treating step
comprises a first heating step performed for about one hour at a
temperature between about 1800 and about 1850.degree. F., followed
by a second heating step performed for between about four and about
eight hours at a temperature between about 1050 and about
1100.degree. F.
33. The method of claim 32, wherein the titanium alloy surface
being repaired comprises Ti-8Al-1Mo-1V.
Description
TECHNICAL FIELD
[0001] The present invention relates to repair and overhaul of
turbine engine components. More particularly, the present invention
relates to methods for repairing turbine engine components made
from titanium alloys.
BACKGROUND
[0002] Turbine engines are used as the primary power source for
many types of aircrafts. The engines are also auxiliary power
sources that drive air compressors, hydraulic pumps, and industrial
gas turbine (IGT) power generation. Further, the power from turbine
engines is used for stationary power supplies such as backup
electrical generators for hospitals and the like.
[0003] Most turbine engines generally follow the same basic power
generation procedure. Compressed air generated by axial and/or
radial compressors is mixed with fuel and burned, and the expanding
hot combustion gases are directed against stationary turbine vanes
in the engine. The vanes turn the high velocity gas flow partially
sideways to impinge on the turbine blades mounted on a rotatable
turbine disk. The force of the impinging gas causes the turbine
disk to spin at high speed. Jet propulsion engines use the power
created by the rotating turbine disk to draw more air into the
engine and the high velocity combustion gas is passed out of the
gas turbine aft end to create forward thrust. Other engines use
this power to turn one or more propellers, fans, electrical
generators, or other devices.
[0004] Low and high pressure compressor (LPC/HPC) components such
as compressor blades and impellers are primary components in the
cold section for any turbine engine, and they must be well
maintained. The LPC/HPC components are subjected to stress loadings
during turbine engine operation, and also are impacted by foreign
objects such as sand, dirt, and other such debris. The LPC/HPC
components can degrade over time due to wear, erosion and foreign
object damage. Sometimes LPC/HPC components are degraded to a point
at which they must be repaired or replaced, which that can result
in significant operating expense and time out of service.
[0005] There are several traditional methods for repairing damaged
turbine engine components, and each method has some limitations in
terms of success. One primary reason for the lack of success is
that the materials used to make LPC/HPC components do not lend
themselves to efficient repair techniques. For example, titanium
alloys are commonly used to make fan and compressor blades because
the alloys are strong, light weight, and highly corrosion
resistant. However, repairing the compressor blade with
conventional welding techniques subjects the compressor blade to
high temperatures at which the welding areas are oxidation-prone.
For this reason, welding conventionally is performed in a
well-shielded atmosphere such as an inert gas chamber or a chamber
that is under vacuum. Maintaining such a controlled environment is
inefficient in terms of both time and expense.
[0006] Also, conventional techniques for repairing titanium alloy
components which are made of alpha-beta alloys with high beta
stabilizers such as Ti-6Al-2Sn-4Zr-6Mo possibly cause the
components to crack while in a welding zone and/or a heat-affected
zone because the alloy components have limited weldability.
Resistance to cracking can be improved by preheating the components
before welding and then stress relieving immediately after welding.
However, combining preheating and welding is inefficient in terms
of both time and expense.
[0007] Hence, there is a need for new repair methods for titanium
alloy components. There is a particular need for new and more
efficient repair methods that improve the reliability and
performance of the repaired components.
BRIEF SUMMARY
[0008] The present invention provides a method for repairing a
titanium alloy surface of a turbine component. The method comprises
the step of cold gas-dynamic spraying a powder material comprising
at least one titanium alloy directly on the titanium alloy
surface.
[0009] In one embodiment, and by way of example only, the method
further comprises hot isostatic pressing the cold gas-dynamic
sprayed turbine component, and a separate heat treating step is
performed after the hot isostatic pressing
[0010] Other independent features and advantages of the preferred
methods will become apparent from the following detailed
description, taken in conjunction with the accompanying drawings
which illustrate, by way of example, the principles of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic view of an exemplary cold gas-dynamic
spray apparatus in accordance with an exemplary embodiment;
[0012] FIG. 2 is a perspective view of an exemplary compressor
turbine blade in accordance with an exemplary embodiment; and
[0013] FIG. 3 is a flow diagram of a repair method in accordance
with an exemplary embodiment.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0014] The following detailed description of the invention is
merely exemplary in nature and is not intended to limit the
invention or the application and uses of the invention.
Furthermore, there is no intention to be bound by any theory
presented in the preceding background of the invention or the
following detailed description of the invention.
[0015] The present invention provides an improved method for
repairing LPC/HPC components. The method utilizes a cold
gas-dynamic spray technique to apply high-strength titanium alloy
materials to worn LPC/HPC component surfaces. These materials can
be used to repair components such as compressor and fan blades and
vanes, including impeller and blisk blades, which have been
degraded due to erosion and foreign object damage, to name several
examples.
[0016] Turning now to FIG. 1, an exemplary cold gas-dynamic spray
system 100 is illustrated diagrammatically. The system 100 is
illustrated as a general scheme, and additional features and
components can be implemented into the system 100 as necessary. The
main components of the cold-gas-dynamic spray system 100 includes a
powder feeder for providing repair powder materials, a carrier gas
supply (typically including a heater), a mixing chamber and a
convergent-divergent nozzle. In general, the system 100 mixes the
repair particles with a suitable pressurized gas in the mixing
chamber. The particles are accelerated through the specially
designed nozzle and directed toward a target surface on the turbine
component. When the particles strike the target surface, converted
kinetic energy causes plastic deformation of the particles, which
in turn causes the particle to form a bond with the target surface.
Thus, the cold gas-dynamic spray system 100 can bond repair powder
materials to an LPC/HPC component surface and thereby restore
degraded LPC/HPC component geometry and dimensions.
[0017] The cold gas dynamic spray process is referred to as a "cold
gas" process because the particles are mixed and applied at a
temperature that is far below the melting point of the particles.
The kinetic energy of the particles on impact with the target
surface, rather than particle temperature, causes the particles to
plastically deform and bond with the target surface. Therefore,
bonding to the LPC/HPC component surface takes place as a solid
state process with insufficient thermal energy to transition the
solid powders to molten droplets.
[0018] According to the present invention, the cold gas-dynamic
spray system 100 applies high-strength titanium alloy materials
that are difficult to weld or otherwise apply to LPC/HPC component
surfaces and other titanium alloy substrates. For example, titanium
alloy welding processes are conventionally performed in a
well-shielded atmosphere such as an inert gas chamber or a chamber
that is under vacuum. Maintaining such a controlled environment is
inefficient in terms of both time and expense. In contrast, the
cold gas-dynamic spray system 100 can be operated at ambient
temperature and pressure environment.
[0019] The cold gas-dynamic spray system 100 is also useful to
spray a wide variety of titanium alloys. Near alpha titanium
alloys, alpha-plus-beta titanium alloys, and near beta titanium
alloys are classes that the system 100 can cold spray. Examples of
the type of titanium alloys that can be cold sprayed using the
system 100 include Ti-6Al-4V, Ti-6Al-2Sn-4Zr-6Mo,
Ti-6Al-2Sn-4Zr-2Mo, Ti-8Al-1Mo-1V,
Ti-5.8Al-4Sn-3.5Zr-0.7Nb-0.5Mo-0.35Si, as well as specially
formulated and tailored alloys. In an exemplary embodiment of the
invention, the cold sprayed titanium alloy is selected to be the
same material that forms the LPC/HPC component to be repaired,
although it is clearly within the scope of the present invention to
select a titanium alloy that is different from the LPC/HPC
component material.
[0020] As previously mentioned, the cold gas-dynamic spray process
can be used to repair a variety of different turbine engine
components. For example, the turbine blades in the high pressure
stages of a turbine engine are particularly susceptible to wear,
erosion and other degradation. Turning now to FIG. 2, a compressor
blade 150 that is exemplary of the types that are used in turbine
engines is illustrated, although compressor blades commonly have
different shapes, dimensions and sizes depending on gas turbine
engine models and applications. The blade 150 includes several
components that are particularly susceptible to wear, erosion and
foreign object damage, and the process of the present invention can
be tailored to repair different blade components. Among such blade
components is an airfoil 152, which is a smooth, curved structure.
The airfoil 152 includes one concave face and one convex face. In
operation, air is drawn into the compressor where multiple stages
of compressor airfoils act to compress the air in preparation for
combustion with some type of fuel. The airfoil 152 includes a
leading edge 162 and a trailing edge 164 that encounter air
streaming around the airfoil 152. The compressor blade 150 also
includes a tip 160. In some applications the tip may include
features commonly known as squealers. The compressor blade 150 is
mounted on a non-illustrated compressor hub or rotor disk by way of
a dovetail 154 that extends downwardly from the airfoil 152 and
engages with a slot on the compressor hub. A platform 156 extends
longitudinally outwardly from the area where the airfoil 152 is
joined to the dovetail 154. Common features on some compressor and
fan blades are midspan dampers or snubbers 158, which are typically
centrally located on each side of the airfoil 152. The dampers or
snubbers 158 extend outwardly to engage with mating features of
adjacent compressor or fan blades within the rotor. This engagement
makes the dampers or snubbers 158 common wear features that can be
repaired according to the method of the present invention. Other
compressor configurations include blisks or integrally bladed
rotors (IBRs) and impellers or centrifugal compressors, which have
blades that are integral to the rotor hub.
[0021] As mentioned previously, the process of the present
invention can be tailored to fit the blade's specific needs, which
depend in part on the blade component where degradation has
occurred. For example, the airfoil tip 160 is particularly subject
to degradation due to rubbing and other contact with the static
shroud, in addition to foreign particle impacts, and the cold gas
dynamic spray process of the present invention is used to apply
materials to the blade tip 160 by filling any material defects with
titanium alloy material. Following the cold spraying process, the
tip 160 is machined to restore the tip 160 to the original design
dimensions.
[0022] As another example, degradation on the leading edge 162 and
trailing edge 164 of the airfoil 152 can be repaired using the cold
gas-dynamic spray process. The leading edge 162 and trailing edge
164 are both subject to degradation, again typically due to tip
rubs and foreign particle impacts. In this application, the cold
gas dynamic spray process is used to apply materials that return
the edges of the compressor blade back to the required dimensions.
Again, this can be done by filling the worn surface and other
defects with cold gas-dynamic sprayed repair material followed by
dimensional restoration and post-spray processing.
[0023] As another example, degradation on the platform 156 can be
repaired using the cold gas-dynamic spray process. In some
applications, wear on the platform 156 occurs at the contact
surfaces 166 between adjacent compressor blades as well as the
dovetail contact surface 154. At those locations, the friction can
cause fretting and other wear. The cold gas-dynamic spray process
can be used to fill the worn surface, cracks and other defects on
the platform and dovetail to restore the desired dimensions.
[0024] Again, the above repair processes are just examples of how a
typical titanium alloy compressor blade can be repaired by cold
gas-dynamic spraying according to the present invention. It is also
emphasized again that compressor blades are just one example of the
type of titanium alloy components that can be repaired using a cold
gas-dynamic spray process. For example, many gas turbine engines
include a shroud structure that surrounds a row of compressor
blades at the outer radial end of the blades. The shroud, like the
blade tips, can be subject erosion and repaired using the cold
gas-dynamic spray process. Other turbine engine components that can
be repaired in such a manner include compressor stator vanes, vane
support structures, rotor nozzles and other LPC/HPC components.
[0025] A variety of different systems and implementations can be
used to perform the cold gas-dynamic spraying process. For example,
U.S. Pat. No 5,302,414, entitled "Gas-Dynamic Spraying Method for
Applying a Coating" and incorporated herein by reference, describes
an apparatus designed to accelerate materials having a particle
size of between 5 to about 50 microns, and to mix the particles
with a process gas to provide the particles with a density of mass
flow between 0.05 and 17 g/s-cm.sup.2. Supersonic velocity is
imparted to the gas flow, with the jet formed at high density and
low temperature using a predetermined profile. The resulting gas
and powder mixture is introduced into the supersonic jet to impart
sufficient acceleration to ensure a particle velocity ranging
between 300 and 1200 m/s. In this method, the particles are applied
and deposited in the solid state, i.e., at a temperature which is
considerably lower than the melting point of the powder material.
The resulting coating is formed by the impact and kinetic energy of
the particles which gets converted to high-speed plastic
deformation, causing the particles to bond to the surface. The
system typically uses gas pressures of between 5 and 20 atm, and at
a temperature of up to 750.degree. F. As non limiting examples, the
gases can comprise air, nitrogen, helium and mixtures thereof.
Again, this system is but one example of the type of system that
can be adapted to cold spray powder materials to the target
surface.
[0026] Turning now to FIG. 3, an exemplary method 200 for repairing
turbine components is illustrated. This method includes the cold
gas-dynamic spray process described above, and also includes
additional optional processes to optimize the resulting repairs. As
described above, cold gas-dynamic spray involves "solid state"
processes to effect bonding and coating build-up, and does not rely
on the application of external thermal energy for bonding to occur.
However, thermal energy may be provided after bonding has occurred
since thermal energy promotes formation of the desired
microstructure and phase distribution for the repaired components.
Also, additional processing may be necessary to optimize bonding
within the material and many thermo-mechanical properties for the
material such as the elastic/plastic properties, mechanical
properties, thermal conductivity and thermal expansion properties.
In the method 200, additional optional processing includes vacuum
sintering, hot isostatic pressing and additional thermal treatments
to consolidate and homogenize the cold gas-dynamic spray applied
material and to restore metallurgical integrity to the repaired
turbine component.
[0027] The first step 202 comprises preparing the repair surface on
the turbine component. For example, the step of preparing a
compressor blade can involve pre-machining, degreasing and grit
blasting the surface that needs to be repaired to remove any
oxidation and dirty materials.
[0028] The next step 204 comprises performing a cold gas-dynamic
spray of repair materials on the turbine component. As described
above, in cold gas-dynamic spraying, particles at a temperature
well below their melting temperature are accelerated and directed
to a target surface on the turbine component. When the particles
strike the target surface, the kinetic energy of the particles is
converted into plastic deformation of the particle, causing the
particle to form a strong bond with the target surface. The
spraying step can include the application of repair material to a
variety of different components in the turbine engine. For example,
material can be applied to worn surfaces on compressor blades,
impellers, and vanes in general, and to blade tips, knife seals,
leading/trailing edges, and platforms. In all these cases, the
spraying step 204 generally returns the component to its desired
dimensions.
[0029] With the repair materials deposited directly on the turbine
component surfaces, the next step 206 comprises performing a vacuum
sintering. In vacuum sintering, the repaired turbine component is
diffusion heat treated at a desired temperature in a vacuum for a
period of time. The vacuum sintering enables metallurgical bonding
to occur across splat interfaces through elemental diffusion. The
vacuum sintering can also remove inter-particle micro-porosity,
homogenize and consolidate the cold-sprayed buildup via an atom
diffusion mechanism. The thermal process parameters for the vacuum
sintering depend on the titanium alloy that forms the turbine
component.
[0030] The next step 208 comprises performing a hot isostatic
pressing on the repaired turbine component. The hot isostatic
pressing (HIP) is a high temperature, high-pressure process. The
HIP process can be performed at a desired temperature that is
sufficient to fully consolidate the cold-sprayed buildup and
eliminate defects such as porosity. Additionally, the HIP process
strengthens bonding between the repair material buildup and the
underlying component, homogenizes the applied materials, and
rejuvenates microstructures in the base material. Overall
mechanical properties such as tensile and stress rupture strengths
of repaired gas turbine components can thus be dramatically
improved with the HIP process.
[0031] As one example of HIP parameters, pressing can be performed
for 2 to 4 hours at temperatures of between about 1650 and about
1750.degree. F. and at pressures of about 10 to about 15 ksi for
most titanium alloys, although the procedure is carried out at up
to about 30 ksi for some high-temperature titanium alloys. Of
course, this is just one example of the type of hot isostatic
pressing process that can be used to remove defects after the
application of repair materials.
[0032] In some embodiments, it may be desirable to perform a rapid
cool following the HIP process to reduce the high-temperature
solution heat treatment aftermath that could otherwise exist. One
advantage of the rapid cool capability is that the component alloy
and the repair material are retained in "solution treated
condition," reducing the need for another solution treatment
operation. In other words, the HIP followed by rapid cool can
provide a combination of densification, homogenization and solution
treat operation. Using this technique can thus eliminate the need
for other heat treatment operations.
[0033] The next step 210 comprises performing a heat treatment on
the repaired component. The heat treatment can provide a full
restoration of the mechanical properties of turbine components. It
should be noted that in some applications it may be desirable to
delete the high temperature solution treatment if such operation
can be accomplished in steps 204 and/or 206. However, some examples
of heat treatments are described below for applications in which
such a treatment is desired or necessary.
[0034] A two-stage heat treatment is applied in a first example,
which is useful for repairing the Ti-6Al-4V alloy, among others.
According to this example, a compressor blade or other component is
heated for about one hour at a temperature between about 1725 and
about 1775.degree. F. After cooling the component with water, the
component is heated between about two and about eight hours at a
temperature between about 900 and about 1100.degree. F.
[0035] Another two-stage heat treatment is applied in a second
example, which is useful for repairing the Ti-6Al-2Sn-4Zr-6Mo
alloy, among others. According to this second example, a compressor
blade or other component is heated for about one hour at a
temperature between about 1550 and about 1650.degree. F. The
component is air cooled, and then heated between about four and
about eight hours at a temperature between about 1075 and about
1125.degree. F.
[0036] Yet another two-stage heat treatment is applied in a third
example, which is useful for repairing the Ti-8Al-1Mo-1V alloy,
among others. According to this third example, a component is
heated for about one hour at a temperature between about 1800 and
about 1850.degree. F. The component is then cooled with water or
oil. The component is then heated between about four and about
eight hours at a temperature between about 1050 and about
1100.degree. F.
[0037] The present invention thus provides an improved method for
repairing turbine engine components. The method utilizes a cold
gas-dynamic spray technique to repair degradation in fan blades,
compressor blades, impellers, blisks, and other turbine engine
components. These methods can be used to repair a variety of
defects thus can improve the overall durability, reliability and
performance of the turbine engine themselves.
[0038] 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 to 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.
* * * * *