U.S. patent application number 11/799012 was filed with the patent office on 2009-03-12 for layered structures with integral brazing materials.
This patent application is currently assigned to United Technologies Corporation. Invention is credited to Christopher J. Bischof, Jason E. Huxol, Michael J. Minor, Paul M. Pellet.
Application Number | 20090068446 11/799012 |
Document ID | / |
Family ID | 39708874 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090068446 |
Kind Code |
A1 |
Bischof; Christopher J. ; et
al. |
March 12, 2009 |
Layered structures with integral brazing materials
Abstract
A layered structure comprising a base structure having a major
surface, and a brazing layer secured to the major surface of the
base structure, where the brazing layer is applied to the major
surface prior to positioning the layered structure in contact with
a turbine engine component.
Inventors: |
Bischof; Christopher J.;
(Southlake, TX) ; Minor; Michael J.; (Arlington,
TX) ; Pellet; Paul M.; (Arlington, TX) ;
Huxol; Jason E.; (Mansfield, TX) |
Correspondence
Address: |
KINNEY & LANGE, P.A.
THE KINNEY & LANGE BUILDING, 312 SOUTH THIRD STREET
MINNEAPOLIS
MN
55415-1002
US
|
Assignee: |
United Technologies
Corporation
Hartford
CT
|
Family ID: |
39708874 |
Appl. No.: |
11/799012 |
Filed: |
April 30, 2007 |
Current U.S.
Class: |
428/336 ; 29/889;
29/889.7; 428/457 |
Current CPC
Class: |
B23K 2103/26 20180801;
Y10T 29/49316 20150115; B23K 1/0018 20130101; Y10T 29/49336
20150115; Y10T 428/31678 20150401; B23K 1/20 20130101; B23K
2101/001 20180801; Y10T 428/265 20150115; F01D 5/30 20130101 |
Class at
Publication: |
428/336 ; 29/889;
29/889.7; 428/457 |
International
Class: |
B32B 15/00 20060101
B32B015/00; B21D 53/78 20060101 B21D053/78; B32B 5/00 20060101
B32B005/00 |
Claims
1. A layered structure for use with a turbine engine component, the
layered structure comprising: a base structure having a major
surface; and a brazing layer secured to the major surface of the
base structure, the brazing layer being applied to the major
surface prior to positioning the layered structure in contact with
the turbine engine component.
2. The layered structure of claim 1, wherein the brazing layer has
a thickness ranging from about 25 micrometers to about 250
micrometers.
3. The layered structure of claim 2, wherein the thickness of the
brazing layer ranges from about 25 micrometers to about 130
micrometers.
4. The layered structure of claim 1, wherein the turbine engine
component is selected from the group consisting of high pressure
turbine blades, low pressure turbine blades, high pressure turbine
vanes, low pressure turbine vanes, blade outer airseals, shrouds,
bearing housings, ducts, and supports.
5. The layered structure of claim 1, wherein the major surface is a
first major surface and the brazing layer is a first brazing layer,
wherein the base structure also has a second major surface opposite
the first major surface, and wherein the layered structure further
comprises a second brazing layer secured to the second major
surface of the base structure.
6. The layered structure of claim .about.1, wherein the brazing
layer is derived from a brazing material selected from the group
consisting of nickel, nickel-based alloys, nickel-based
superalloys, cobalt, cobalt-based alloys, cobalt-based superalloys,
and combinations thereof.
7. A method for manufacturing a turbine engine component, the
method comprising: providing a layered structure having a major
surface and a brazing layer secured to the major surface;
positioning the layered structure onto a turbine engine component
surface such that at least a portion of the brazing layer contacts
the turbine engine component surface; heating the turbine engine
component containing the layered structure; and cooling the turbine
engine component, thereby fusing the layered structure to the
turbine engine component with the brazing layer.
8. The method of claim 7, further comprising: coating a brazing
material onto the major surface of the layered structure; and
fusing the brazing material to the layered structure.
9. The method of claim 7, wherein heating the turbine engine
component containing the layered structure comprises heating the
turbine engine component to a temperature ranging from about
1200.degree. C. to about 1260.degree. C.
10. The method of claim 7, wherein the major surface is a first
major surface and the brazing layer is a first brazing layer,
wherein the layered structure also has a second major surface
opposite the first major surface, and wherein the layered structure
further comprises a second brazing layer secured to the second
major surface.
11. The method of claim 7, further comprising: coating a brazing
material onto a master sheet; fusing the brazing material to the
master sheet; and separating the master sheet into multiple plates,
the layered structure being one of the multiple plates.
12. The method of claim 7, wherein the brazing layer has a
thickness ranging from about 25 micrometers to about 250
micrometers.
13. The method of claim 12, wherein the thickness of the brazing
layer ranges from about 25 micrometers to about 130
micrometers.
14. The method of claim 7, wherein the brazing layer is derived
from a brazing material selected from the group consisting of
nickel, nickel-based alloys, nickel-based superalloys, cobalt,
cobalt-based alloys, cobalt-based superalloys, and combinations
thereof.
15. A method for manufacturing an airfoil component, the method
comprising: determining an amount of brazing material required to
perform a brazing operation; coating a brazing material onto the
major surface of the cover plate; and fusing the brazing material
to the cover plate to form a brazing layer having a thickness based
at least in part on the determined amount of brazing material;
positioning the cover plate such that at least a portion of the
brazing layer contacts an airfoil component surface; and brazing
the airfoil component containing the cover plate.
16. The method of claim 15, wherein brazing the airfoil component
containing the cover plate comprises: heating the airfoil component
containing the cover plate comprises heating the airfoil component
to a temperature ranging from about 1200.degree. C. to about
1260.degree. C.; and cooling the heated airfoil component.
17. The method of claim 15, wherein the thickness of the brazing
layer ranges from about 25 micrometers to about 250
micrometers.
18. The method of claim 17, wherein the thickness of the brazing
layer ranges from about 25 micrometers to about 130
micrometers.
19. The method of claim 15, wherein the major surface is a first
major surface and the brazing layer is a first brazing layer,
wherein the cover plate also has a second major surface opposite
the first major surface, and wherein the cover plate further
comprises a second brazing layer secured to the second major
surface.
20. The method of claim 15, wherein the brazing layer is derived
from a brazing material selected from the group consisting of
nickel, nickel-based alloys, nickel-based superalloys, cobalt,
cobalt-based alloys, cobalt-based superalloys, and combinations
thereof.
Description
BACKGROUND
[0001] The present invention relates to manufacturing components
and processes for aerospace applications. In particular, the
present invention relates to gas turbine engine components and
brazing operations for manufacturing gas turbine engine
components.
[0002] During the manufacture of gas turbine engines, many turbine
engine components are secured together with brazing operations. For
example, when manufacturing hollow turbine airfoil components
(e.g., components of turbine blades and vanes), the passages of the
airfoil components are typically covered with cover plates (e.g.,
meter plates). The cover plates are tack welded onto the airfoil
component, and then a brazing alloy is applied externally to fill
the gaps between the cover plate and the airfoil component via
capillary action. The resulting covered airfoil component is then
placed in a furnace to fuse the cover plate to the airfoil
component with the brazing alloy. However, the steps of applying
the brazing alloy and the furnace treatment are typically repeated
to ensure all of the gaps are adequately filled. This increases the
time required to manufacture the covered airfoil components.
[0003] Additionally, excess amounts of the applied brazing alloy
can flow into the hollow regions of the airfoil component, thereby
requiring extra steps for applying and stopping of the brazing
alloy. Excess amounts of brazing alloy may be particularly
problematic if the brazing alloy flows into critical areas of the
airfoil components during the brazing operation. This may result in
the need to recycle or scrap the airfoil component. Accordingly, to
ensure that gaps are adequately filled, while also preventing an
excess amount of brazing alloy from being applied, brazing
operations require monitoring by personnel. Thus, brazing
operations cannot be readily automated without the use of expensive
monitoring systems to apply the brazing alloys where needed.
Consequentially, there is a need for turbine engine components
(e.g., cover plates and airfoils) that are readily securable with
brazing operations, thereby reducing the complexity time, and cost
of performing the brazing operations during manufacturing.
SUMMARY
[0004] The present invention relates to a layered structure for use
with a turbine engine component, and a method of securing the
layered structure to the turbine engine component. The layered
structure includes a base structure and a brazing alloy layer
secured to a major surface of the base structure. The brazing alloy
layer is applied to the major surface prior to positioning the
layered structure in contact with the turbine engine airfoil
component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a bottom perspective view of a turbine blade root
containing an airfoil cover plate being secured to a surface of the
turbine blade root.
[0006] FIG. 2 is an expanded sectional view of section 2-2 taken in
FIG. 1, further illustrating the airfoil cover plate, which
includes a brazing alloy layer secured to a base plate.
[0007] FIG. 3 is an alternative expanded sectional view of section
2-2 taken in FIG. 1 showing an alternative airfoil cover plate that
includes a pair of brazing alloy layers secured to a base
plate.
[0008] FIG. 4 is a flow diagram of a method of forming a covered
airfoil component with an airfoil cover plate of the present
invention.
[0009] FIG. 5 is a flow diagram of an alternative method of forming
a covered airfoil component with an airfoil cover plate of the
present invention.
DETAILED DESCRIPTION
[0010] FIG. 1 is a bottom perspective view of blade root 10, which
is a turbine blade root that is insertable into a dovetail slot
(not shown) of a supporting rotor disk (not shown). Blade root 10
is an example of a suitable turbine engine component for use with
the present invention, and includes surface 12, inlet apertures 14,
and cover plate 16. Surface 12 is a wall segment extending across
the bottom of blade root 10. Inlet apertures 14 are openings within
surface 12 for receiving cooling air during operation. Cover plate
16 is disposed over surface 12 and inlet apertures 14. When cover
plate 16 is secured to surface 12, cover plate 16 extends over
inlet apertures 14 and functions as a meter plate for restricting
the flow of air through inlet apertures 14 during operation.
[0011] Cover plate 16 is an airfoil cover plate that includes a
pre-applied layer of a brazing material (not shown in FIG. 1), and
is an example of a suitable layered structure of the present
invention. During the manufacture of blade root 10, cover plate 16
may be secured to surface 12 via a brazing operation without
requiring a separate step of applying a brazing alloy between
surface 12 and cover plate 16. Cover plate 16 is positioned in
contact with surface 12 at a desired location (e.g., over inlet
apertures 14), tack welded in place, and then placed in a furnace
to fuse cover plate 16 to surface 12 with the pre-applied brazing
material. This reduces the time required to perform the brazing
operation, and allows the brazing operation to be performed in an
automated manner without requiring expensive monitoring
systems.
[0012] FIG. 2 is an expanded sectional view of section 2-2 taken in
FIG. 1, further illustrating cover plate 16. As shown, cover plate
16 includes base plate 18 and brazing layer 20, where base plate 18
is a metallic plate that includes opposing major surfaces 22 and
24. Base plate 18 may be cast or otherwise formed from a variety of
different metals and alloys used in aerospace applications.
Examples of suitable materials for base plate 18 include nickel,
nickel-based alloys and superalloys, cobalt, cobalt-based alloys
and superalloys, and combinations thereof; and may also include one
or more additional materials such as carbon, titanium, chromium,
niobium, hafnium, tantalum, molybdenum, tungsten, aluminum, and
iron. Examples of particularly suitable alloys for base plate 18
include those that meet Aerospace Materials Specification (AMS)
5536 and 5537. Examples of suitable commercially available
materials for base plate 18 include
nickel-chromium-iron-molybdenum-based alloys under the trademark
"HASTELLOY.RTM. X" (meet AMS 5536), and
nickel-cobalt-chromium-tungsten-based alloys under the trademark
"HAYNES 25.TM. (L605)" (meet AMS 5537), both from Haynes
International, Inc., Kokomo, Ind.
[0013] Brazing layer 20 is a layer (or multiple layers) of a
brazing material secured to surface 22. The brazing material for
brazing layer 20 may also be derived from a variety of different
metals and alloys used in aerospace applications. Examples of
suitable brazing materials for brazing layer 20 include the
suitable materials discussed above for base plate 18. Examples of
particularly suitable alloys for brazing layer 20 include those
that meet AMS 4777 and 4778. The brazing material for brazing layer
20 may be provided in a variety of media, such as powders,
dispersions, slurries, pastes, foils, and tapes.
[0014] The brazing material is secured to surface 22 by coating the
brazing material onto surface 22, and then fusing (e.g., sintering)
the brazing material to surface 22, thereby forming brazing layer
20. The technique for coating the brazing material onto surface 22
may vary depending on the medium of the brazing material (e.g.,
powder). Examples of suitable coating techniques include deposition
coating, electrostatic plating, plasma deposition, and lamination
coating. Deposition coating processes are beneficial for brazing
materials provided as powders, dispersions, and pastes. A suitable
deposition coating process involves physically depositing the
brazing material onto an upward-facing surface 22, and then drying
the coating (for dispersions and pastes).
[0015] Electrostatic plating processes are beneficial for brazing
materials provided as powders and dispersions. A suitable
electrostatic plating process involves placing base plate 18 in a
plating solution containing the brazing material, and then inducing
a current between a cathode (connected to base plate 18) and an
anode, thereby causing ions of the brazing material to deposit onto
surface 22. Suitable plasma deposition processes include corona
treatment processes, and may involve initiating a plasma reaction
adjacent to surface 22, thereby allowing ions of the brazing
material to deposit onto surface 22. Lamination coating processes
are beneficial for brazing materials provided as dispersions and
pastes. Suitable lamination coating processes include extrusion and
knife coating techniques, where the coated cover plate may be
subsequently dried.
[0016] The brazing material may be fused to base plate 18 by
heating (e.g., furnace heating) cover plate 16 to a suitable
temperature, and for a suitable duration, to interdiffuse at least
a portion of the brazing material with the material of base plate
16. Suitable temperatures and durations for fusing the braze
material to base plate 18 generally depend on the brazing material
and the material of base plate 18. In one embodiment, the brazing
material is heated using an initial, high-temperature, melting
step, which is followed by a longer, lower-temperature, diffusion
step. Examples of suitable temperatures for the melting step range
from about 1200.degree. C. (about 2200.degree. F.) to about
1260.degree. C. (about 2300.degree. F.), and examples of suitable
durations for the melting step range from about 5 minutes to about
30 minutes. Examples of suitable temperatures for the diffusion
step range from about 1100.degree. C. (about 2000.degree. F.) to
about 1200.degree. C. (about 2200.degree. F.), and examples of
suitable durations for the diffusion step range from about 1 hour
to about 20 hours.
[0017] The amount of brazing material coated onto surface 22
generally determines the thickness of brazing layer 20.
Correspondingly, this also dictates the amount of brazing material
that is available during a brazing operation to fuse cover plate 16
to surface 12 of blade root 10 (shown in FIG. 1). Thus, for a
particular brazing operation, an appropriate amount of brazing
material may be pre-applied to base plate 18, as measured by the
thickness of brazing layer 20. This precludes the need to manually
apply brazing materials to gaps between surface 12 and cover plate
16, which is otherwise required to ensure that the amount of
brazing material applied is neither deficient nor excessive.
[0018] Suitable thicknesses for the brazing layer (e.g., brazing
layer 20) may vary depending on the particular application.
However, for base plate thicknesses ranging from about 0.25
millimeters (about 0.01 inches) to about 2.5 millimeters (about 0.1
inches), examples of suitable thicknesses for the brazing layer
range from about 25 micrometers (about 0.001 inches) to about 250
micrometers (about 0.01 inches), with particularly suitable
thicknesses ranging from about 25 micrometers (about 0.001 inches)
to about 130 micrometers (about 0.005 inches). The brazing layer
thicknesses discussed herein refer to thicknesses obtained after
the brazing material is secured (e.g., fused) to the base plate
18.
[0019] Brazing layer 20 is desirably coated onto (and secured to)
base plate 18 across the entire surface area of surface 22. This
allows brazing material to be available to fuse any point across
surface 22 to an airfoil component. This also precludes the need to
mask or otherwise pattern surface 22 to coat the brazing material
at particular locations on surface 22. In alternative embodiments,
however, brazing layer 20 may be secured to base plate 18 over only
one or more portions of the surface 22, as individual needs may
necessitate.
[0020] In one embodiment, the thickness of brazing layer 20 may
vary at different points across surface 22 (i.e., non-uniform
thicknesses). This may be accomplished by varying the amount of
brazing material that is coated onto surface 22. This is beneficial
for brazing operations that require different amounts of brazing
material at different locations. For example, when cover plate 16
is positioned against surface 12 of blade root 10, a first location
between surface 12 and cover plate 16 may require a first amount of
brazing material to form a suitable weld, while a second location
may require a second amount of brazing material to form a suitable
weld. Varying the thickness of brazing layer 20 allows the
appropriate amounts of brazing material to be used for each
location without causing an excess or deficiency of brazing
material at the other locations.
[0021] FIG. 3 is an alternative expanded sectional view of section
2-2 taken in FIG. 1, which includes cover plate 26. Cover plate 26
is an alternative to cover plate 16 (shown in FIG. 2), and includes
base plate 28 and brazing layers 30a and 30b, where base plate 28
includes opposing major surfaces 32 and 34. Base plate 28 is
metallic plate similar to base plate 18 (shown in FIG. 2), and may
be cast or otherwise molded from the same materials discussed above
for base plate 18. Brazing layers 30a and 30b are layers of brazing
materials similar to brazing layer 20 (shown in FIG. 2), which are
secured to surface 32 and 34, respectively. Suitable brazing
materials, methods of coating and fusing, and thicknesses for
brazing layers 30a and 30b are the same as those discussed above
for brazing layer 20.
[0022] Cover plate 26 is beneficial for allowing an error-free
application during a brazing operation. Because both major surfaces
of base plate 28 (i.e., surfaces 32 and 34) are covered with
brazing layers (i.e., brazing layers 30a and 30b), either major
surface of cover plate 26 can be fused to surface 12 (shown in FIG.
1). As such, the manufacturer is not required to determine which
major surface of cover plate 26 needs to face surface 12. This
reduces the time and effort required to secure cover plate 26 to
surface 12.
[0023] While the above-discussed embodiments involve the use of
cover plates (i.e., cover plates 16 and 26) for covering inlet
apertures 14 of blade root 10, layered structures of the present
invention may be used with any turbine engine component (e.g.,
turbine blades and vanes) that require brazed base structures
(e.g., base plates 18 and 28) during manufacturing. For example,
many airfoil components require wrought alloy plates that are not
castable with the airfoil component. Such plates may be coated with
brazing materials as discussed above, and then subsequently fused
to the airfoil components with the brazing materials. This
correspondingly increases the throughput of the airfoil components
during manufacturing. Examples of suitable turbine engine
components that may be used with layered structures of the present
invention include high pressure turbine blades, low pressure
turbine blades, high pressure turbine vanes, low pressure turbine
vanes, blade outer airseals, shrouds, and structural components
such as bearing housings, ducts, and supports.
[0024] FIG. 4 is a flow diagram of method 36 for forming a turbine
engine component with a layered structure of the present invention
(e.g., cover plates 16 and 26, shown in FIGS. 1-3). The following
discussion of method 36 is made with reference to an airfoil
component with the understanding that method 36 may also be used to
form a variety of turbine engine components. As shown, method 36
includes steps 38-50, and initially involves predetermining a
required amount of brazing material that is needed for a particular
brazing operation (step 38). As discussed above, the required
amount of brazing material is desirably an appropriate amount that
reduces the risk of having an excess or deficiency of brazing
material. The predetermined amount of brazing material may be
measured as a desired thickness of a brazing layer (or thicknesses
for a non-uniformly thick layer).
[0025] The brazing material is then coated onto a major surface of
an airfoil cover plate (step 40). Suitable cover plate materials,
brazing materials, and methods of coating are the same as those
discussed above for base plate 18 and brazing layer 20 (shown in
FIG. 2). The amount of brazing material coated is desirably based
on the intended thickness (or thicknesses) of the brazing layer,
which is correspondingly based on the predetermined amount of
brazing material to be used.
[0026] The brazing material is then fused to the surface of the
cover plate to form a brazing layer (step 42). Suitable techniques
for fusing the brazing material to the surface of the cover plate
include those discussed above for brazing layer 20. As discussed
above, each major surface of the cover plate (e.g., cover plate 26)
may be coated with brazing material to form a pair of brazing
layers, thereby providing an error-free application during a
brazing operation.
[0027] The cover plate is then positioned against a surface of an
airfoil component such that the brazing layer contacts the surface
of the airfoil component (step 44). The cover plate is then tack
welded or otherwise adhered to the surface of the airfoil component
to prevent the cover plate from moving during the brazing operation
(step 46). The covered airfoil component is then heated to fuse the
cover plate to the surface of the airfoil component with the
brazing layer (i.e., a brazing operation) (step 48). The heating
causes the brazing material of the brazing layer to interdiffuse
into the surface of the airfoil component.
[0028] The brazing operation may be performed in a furnace or other
similar heating system. Suitable temperatures and durations for the
brazing operation generally depend on the brazing material and the
material and the material of the airfoil component. Examples of
suitable temperatures and durations for the brazing operation
includes those discussed above (e.g., the melting and diffusion
steps). After the brazing operation is completed, the covered
airfoil component is then cooled, thereby forming a brazed weld
between the cover plate and the airfoil component (step 50).
[0029] As discussed above, the use of the pre-applied brazing layer
precludes the need for applying a brazing material between the
cover plate and the surface of the airfoil component. The brazing
layer provides an appropriate amount of brazing material to create
a brazed weld that substantially fills the gaps between the cover
plate and the surface of the airfoil component, while also reducing
the amounts of excess brazing material. This accordingly reduces
the time required to perform the brazing operation, and allows the
brazing operation to be performed in an automated manner.
[0030] FIG. 5 is a flow diagram of method 52, which is an
alternative to method 36 (shown in FIG. 4). As discussed below,
method 52 involves the use of a master sheet that is separable into
multiple cover plates, thereby allowing brazing layers to be formed
on multiple cover plates with a single coating operation. Method 52
includes steps 54-68, and initially involves predetermining a
required amount of brazing material that is needed for a particular
brazing operation (step 54). The predetermined amount of brazing
material may be measured as a desired thickness of a brazing layer
(or thicknesses for a non-uniformly thick layer).
[0031] In one embodiment, the multiple cover plates are intended
for a common purpose (e.g., all of the cover plates from the master
sheet will be used in the same manner, such as meter plates). In
this embodiment, the required amount of brazing material may be the
same for each cover plate, thereby allowing a uniform thickness to
be used over the entire master sheet. In another embodiment, the
multiple cover plates are intended for different purposes. In this
embodiment, the required amount of brazing material may be
different for each cover plate. As such, the intended thickness of
the brazing layer may vary over the surface area of the master
sheet.
[0032] The brazing material is then coated onto a major surface of
the master sheet (step 56). Suitable master sheet materials,
brazing materials, and methods of coating are the same as those
discussed above for base plate 18 and brazing layer 20 (shown in
FIG. 2). The amount of brazing material coated is desirably based
on the intended thickness (or thicknesses) of the brazing layer,
which is correspondingly based on the predetermined amount of
brazing material to be used.
[0033] The brazing material is then fused to the surface of the
master sheet to form a brazing layer (step 58). Suitable techniques
for fusing the brazing material to the surface of the master sheet
include those discussed above for brazing layer 20. Alternatively,
each major surface of the master sheet may be coated with brazing
material to form a pair of brazing layers, similar to that
discussed above for meter plate 26 (shown in FIG. 3).
[0034] The master sheet is then separated into multiple cover
plates, where each cover plate includes at least one brazing layer
(step 60). The master sheet may be separated into multiple cover
plates using a variety of techniques, such as laser cutting,
waterjet cutting, and stamping operations. As discussed above, the
use of the master sheet allows a single coating operation to be
used to apply brazing layers onto multiple cover sheets.
[0035] One of the cut-out cover plates is then positioned against a
surface of an airfoil component such that the brazing layer
contacts the surface of the airfoil component (step 62). The cover
plate is then tack welded or otherwise adhered to the surface of
the airfoil component to prevent the cover plate from moving during
the brazing operation (step 64). The covered airfoil component is
then heated (step 66) and cooled (step 68), thereby forming a
brazed weld between the cover plate and the surface of the airfoil
component. Steps 62-68 may then be repeated for each cover sheet
cut-out of the master sheet (as represented by arrow 70).
Accordingly, a single coating operation can be used to apply
brazing layers on multiple cover plates. This precludes the need to
manually apply brazing materials during each brazing operation,
thereby increasing manufacturing throughput.
[0036] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *