U.S. patent application number 12/507503 was filed with the patent office on 2012-01-05 for method of making a combustion turbine component having a plurality of surface cooling features and associated components.
Invention is credited to Mike P. Appleby, Iain A. Fraser, Allister W. James, Jay E. Lane, Gary B. Merrill, Jay A. Morrison, John R. Paulus.
Application Number | 20120000072 12/507503 |
Document ID | / |
Family ID | 43496036 |
Filed Date | 2012-01-05 |
United States Patent
Application |
20120000072 |
Kind Code |
A9 |
Morrison; Jay A. ; et
al. |
January 5, 2012 |
Method of Making a Combustion Turbine Component Having a Plurality
of Surface Cooling Features and Associated Components
Abstract
A method of making a combustion turbine component includes
forming a metallic body by direct metal fabrication (DMF) to have
at least one surface portion defining a first plurality of surface
cooling features each having a first dimension and at least one
second surface cooling feature on at least one of the first
plurality of surface cooling features and having a second dimension
less than said first dimension and less than 200 .mu.m. Forming the
metallic body by DMF may include forming a plurality of metallic
combustion turbine subcomponent greenbodies by DMF and assembling
the plurality of metallic combustion turbine subcomponent
greenbodies together to form a metallic greenbody assembly. The
metallic greenbody assembly may be sintered to thereby form the
metallic body.
Inventors: |
Morrison; Jay A.; (Oviedo,
FL) ; Lane; Jay E.; (Mooresville, IN) ; James;
Allister W.; (Chuluota, FL) ; Merrill; Gary B.;
(Orlando, FL) ; Paulus; John R.; (Afton, VA)
; Appleby; Mike P.; (Crozet, VA) ; Fraser; Iain
A.; (Ruckersville, VA) |
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20110016717 A1 |
January 27, 2011 |
|
|
Family ID: |
43496036 |
Appl. No.: |
12/507503 |
Filed: |
July 22, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12238774 |
Sep 26, 2008 |
|
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12507503 |
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Current U.S.
Class: |
29/889.72 |
Current CPC
Class: |
B22F 3/105 20130101;
Y10T 29/49339 20150115; B22F 3/225 20130101; B22F 5/009
20130101 |
Class at
Publication: |
29/889.72 |
International
Class: |
B21K 3/04 20060101
B21K003/04 |
Goverment Interests
GOVERNMENT CONTRACT
[0001] The U.S. Government has a paid-up license in this invention
and the right in limited circumstances to require the patent owner
to license others on reasonable terms as provided for by the terms
of contract No. DE-FC26-05NT42644 awarded by the Department of
Energy.
Claims
1. A method of making a combustion turbine component comprising:
forming a metallic body by direct metal fabrication (DMF) to have
at least one surface portion defining a plurality of coarse surface
cooling features each having a first dimension, and at least one
fine surface cooling feature on at least one of the plurality of
coarse surface cooling features and having a second dimension less
than said first dimension and less than 200 .mu.m.
2. The method of claim 1 wherein the at least one fine surface
cooling feature comprises a projection.
3. The method of claim 1 wherein the at least one fine surface
cooling feature comprises a convex projection.
4. The method of claim 1 wherein the at least one fine surface
cooling feature comprises a recess.
5. The method of claim 1 wherein the at least one fine surface
cooling feature comprises a concave recess.
6. The method of claim 1 wherein the DMF comprises tomo
lithographic molding.
7. The method of claim 1 wherein the DMF comprises metal injection
molding.
8. The method of claim 1 wherein forming the metallic body by DMF
comprises: forming a plurality of metallic combustion turbine
subcomponent greenbodies by DMF, each of the plurality of metallic
combustion turbine subcomponent greenbodies comprising an
activatable binder; assembling the plurality of metallic combustion
turbine subcomponent greenbodies together to form a metallic
greenbody assembly; activating the activatable binder; and
sintering the metallic greenbody assembly to thereby form the
metallic body.
9. The method of claim 1 wherein the first dimension is greater
than 500 .mu.m.
10. The method of claim 1 wherein at least one of the plurality of
coarse surface cooling features comprises a projection.
11. The method of claim 1 wherein at least one of the plurality of
coarse surface cooling features comprises a recess.
12. The method of claim 1 wherein the metallic combustion turbine
component body comprises at least one of an oxide dispersion
strengthened (ODS) alloy, an intermetallic compound, and a
refractory metal.
13. A method of making a combustion turbine component comprising:
forming a plurality of metallic combustion turbine subcomponent
greenbodies by DMF, at least one of the plurality of metallic
combustion turbine subcomponent greenbodies being formed to have at
least one surface portion defining a plurality of coarse surface
cooling features each having a first dimension greater than 500
.mu.m, and at least one fine surface cooling feature on at least
one of the plurality of coarse surface cooling features and having
a second dimension less than 200 .mu.m; assembling the plurality of
metallic combustion turbine subcomponent greenbodies together to
form a metallic greenbody assembly; and sintering the metallic
greenbody assembly to thereby form the combustion turbine
component.
14. The method of claim 13 wherein the plurality of metallic
combustion turbine subcomponent greenbodies comprises an
activatable binder; and further comprising activating the
activatable binder prior to sintering.
15. The method of claim 13 wherein the at least one fine surface
cooling feature comprises a projection.
16. The method of claim 13 wherein the at least one fine surface
cooling feature comprises a convex projection.
17. The method of claim 13 wherein the at least one fine surface
cooling feature comprises a recess.
18. The method of claim 13 wherein the at least one fine surface
cooling feature comprises a concave recess.
19. The method of claim 13 wherein the DMF comprises tomo
lithographic molding.
20. The method of claim 13 wherein the DMF comprises metal
injection molding.
21. The method of claim 13 wherein at least one of the plurality of
coarse surface cooling features comprises a projection.
22. The method of claim 13 wherein at least one of the plurality of
coarse surface cooling features comprises a recess.
23. The method of claim 13 wherein at least one of the plurality of
metallic combustion turbine subcomponent greenbodies comprises at
least one of an oxide dispersion strengthened (ODS) alloy, an
intermetallic compound, and a refractory metal.
24. A combustion turbine component comprising: a metallic body to
define at least a substrate for the combustion turbine component,
said metallic body having at least one surface portion defining a
plurality of coarse cooling features each having a first dimension,
and at least one fine cooling feature on at least one of said
plurality of coarse cooling features each having a second dimension
less than the first dimension and less than 200 .mu.m.
25. The combustion turbine component of claim 24 wherein the first
dimension is greater than 500 .mu.m.
26. The combustion turbine component of claim 24 wherein the at
least one fine surface cooling feature comprises a projection.
27. The combustion turbine component of claim 24 wherein the at
least one fine surface cooling feature comprises a convex
projection.
28. The combustion turbine component of claim 24 wherein the at
least one fine surface cooling feature comprises a recess.
29. The combustion turbine component of claim 24 wherein the at
least one fine surface cooling feature comprises a concave
recess.
30. The combustion turbine component of claim 24 wherein at least
one of the plurality of coarse surface cooling features comprises a
projection.
31. The combustion turbine component of claim 24 wherein at least
one of the plurality of coarse surface cooling features comprises a
recess.
32. The combustion turbine component of claim 24 wherein the
metallic combustion turbine component body comprises at least one
of an oxide dispersion strengthened (ODS) alloy, an intermetallic
compound, and a refractory metal.
Description
FIELD OF THE INVENTION
[0002] The present invention relates to the field of metallurgy,
and, more particularly, to combustion turbine components having
surface cooling features and associated methods.
BACKGROUND OF THE INVENTION
[0003] A combustion turbine typically includes, in a serial flow
relationship, a compressor section to compress the entering
airflow, a combustion section in which a mixture of fuel and the
compressed air is burned to generate a propulsive gas flow, and a
turbine section that is rotated by the propulsive gas flow. After
passing through the turbine section, the propulsive gas flow exits
the engine through a diffuser section. In ground based combustion
turbines used for electricity generation, power is normally
extracted from the rotating shaft to drive an electrical power
generator.
[0004] A component of such a combustion turbine may advantageously
be precisely formed and may take a variety of complicated shapes.
Some current methods of combustion turbine component formation
include casting and forging.
[0005] Casting is a manufacturing process by which a liquid metal
is poured into a mold, typically ceramic, which contains a hollow
cavity of the desired shape to be formed. The liquid metal is
allowed to solidify and the solid combustion turbine component
casting is then ejected or broken out of the mold to complete the
process. There may, however, be limitations on the size of the
combustion turbine components that may be formed by casting.
Likewise, there may be limitations on the size of surface features
of the combustion turbine components that may be formed (e.g. it
may not be possible to form surface features having dimensions
below a certain size).
[0006] Forging is the term for shaping metal by using localized
compressive forces. A combustion turbine component formed by
forging may be relatively strong and may have a fine grain
structure. However, due to the fine grain structure, a forged
combustion turbine component generally exhibits relatively low
resistance to creep and may thus be unsuitable for use in certain
applications Subsequent heat treatment can promote grain growth,
however, and it is may be easier to control grain size in a forging
than a casting. In addition, the formation of small surface
features on such a combustion turbine component during the forging
process may be difficult. Since forgings are generally solid shapes
and cooling passages are later machined into the forging, it may be
difficult to machine fine scale internal features on an internal
surface of a cooling passage of a forging.
[0007] As discussed above, due to process limitations and cost
concerns, forming an entire combustion turbine component of a
desired shape and having desired surface features by the above
processes may be difficult or costly. Thus, attempts at forming
combustion turbine subcomponents and joining the subcomponents
together to form a whole combustion turbine component have been
made.
[0008] Some efforts have focused on welding. U.S. Pat. No.
7,337,940 to Subramanian et al., for example, discloses a method of
manufacturing a combustion turbine component by friction stir
welding a plurality of combustion turbine subcomponents together.
The combustion turbine subcomponents are formed by conventional
processes, such as casting or forging. However, some features may
not be easily or cost effectively formed by casting or forging
processes. In addition, some combustion turbine subcomponents may
be constructed from materials that are not easily friction stir
welded.
[0009] Other efforts at joining combustion turbine subcomponents
together to form a combustion turbine component have instead
focused on brazing. U.S. Pat. No. 6,434,946 to Shaw et al.
discloses a method of making a combustion turbine component by
bonding a brazing alloy to the surfaces of two combustion turbine
subcomponents to be joined together and assembling the two
combustion turbine subcomponents. The assembly is then heated to a
brazing temperature to form a braze joint between the combustion
turbine subcomponents, thereby forming the combustion turbine
component. However, a braze joint may be undesirable in some
situations and may not provide as strong a bond as desired.
[0010] In addition, the continuing effort to design and build more
powerful and efficient combustion turbines has led to a desire for
a component thereof to have enhanced high performance capabilities,
such as heat transfer. Indeed, a component's ability to transfer
heat away from itself is particularly important due to the high
operating temperatures of combustion turbines.
[0011] Newton's Law of Cooling states that the rate of heat loss of
a body is proportional to both the difference in temperatures
between the body itself and its environment and the surface area of
the body. Therefore, one way to enhance the cooling capabilities of
a combustion turbine component is to increase its surface area.
[0012] U.S. Pat. Pub. 2008/0000611 to Bunker et al., for example,
discloses a method of forming a casting mold that will be used to
cast a combustion turbine component having a variety of surface
cooling features, such as hemispheres, that increase the surface
area of the combustion turbine component. The increased surface
area provides the combustion turbine component with enhanced
cooling capabilities. However, a combustion turbine component
formed by casting and having an increased surface area may not be
desirable in some applications. Furthermore, certain arrangements
of surface cooling features may not be easily formed by casting
techniques.
[0013] U.S. Pat. No. 6,503,574 to Skelly et al. discloses a method
for making a combustion turbine component having cooling grooves
defined therein. A combustion turbine component substrate is formed
by single crystal casting techniques and then a bond coating is
formed on the combustion turbine component substrate. A pattern of
three-dimensional recessed grooves is etched in the bond coating by
photolithography and then a thermal barrier coating is formed on
the bond coating. However, recessed grooves may not provide the
desired cooling capabilities in some applications.
[0014] Therefore, different methods of joining combustion turbine
subcomponents together to form a combustion turbine component may
be desirable. In addition, a combustion turbine component having
increased surface area that is formed by joining a plurality of
combustion turbine subcomponents together may also be
desirable.
SUMMARY OF THE INVENTION
[0015] In view of the foregoing background, it is therefore an
object of the present invention to provide a combustion turbine
component having a plurality of surface cooling features together
with methods of making such a combustion turbine component.
[0016] This and other objects, features, and advantages in
accordance with the present invention are provided by a method of
making a combustion turbine component comprising forming a metallic
combustion turbine component body by direct metal fabrication
(DMF). The metallic combustion turbine component body may be formed
to have at least one surface portion defining a plurality of coarse
surface cooling features each having a first dimension, and at
least one fine surface cooling feature on at least one of the
plurality of coarse surface cooling features and having a second
dimension less than the first dimension and less than 200 .mu.m.
The cooling features increase the surface area of the combustion
turbine component and thereby enhance its ability to transfer heat
away from itself, improving high temperature performance.
[0017] DMF advantageously allows for a greater variety of shapes to
be formed than casting or forging. In addition, DMF allows the
formation of smaller surface features than may be possible with
conventional casting or forging processes.
[0018] The at least one fine surface cooling feature may comprise a
projection, such as a convex projection The at least one fine
surface cooling feature may comprises a recess, such as a concave
recess.
[0019] The DMF may comprise tomo lithographic molding. Additionally
or alternatively the DMF may comprise metal injection molding.
[0020] Forming the metallic combustion turbine component body by
DMF may include forming a plurality of metallic combustion turbine
subcomponent greenbodies by DMF, each of the plurality of metallic
combustion turbine subcomponent greenbodies comprising an
activatable binder. The plurality of metallic combustion turbine
subcomponent greenbodies may be assembled together to form a
metallic greenbody assembly. The activatable binder may be
activated. The metallic greenbody assembly may be sintered to
thereby form the metallic body.
[0021] The first dimension may be greater than 500 .mu.m. At least
one of the plurality of coarse surface cooling features may
comprise a projection or a recess, for example.
[0022] The metallic combustion turbine component body may comprise
at least one of an oxide dispersion strengthened (ODS) alloy, an
intermetallic compound, and a refractory metal. Such materials may
impart the combustion turbine component with various desirable
properties
[0023] Another aspect is directed to a combustion turbine component
comprising a metallic body having at least one surface portion
defining a plurality of coarse cooling features each having a
dimension greater than 500 .mu.m. A plurality of fine cooling
features, each having a dimension less than 200 .mu.m, is on at
least one of the plurality of coarse cooling features.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a flowchart for a method of forming a combustion
turbine component in accordance with the present invention.
[0025] FIG. 2 is a more detailed flowchart for the method of
forming a combustion turbine component in accordance with the
present invention.
[0026] FIG. 3 is another more detailed flowchart for the method of
forming a combustion turbine component in accordance with the
present invention.
[0027] FIG. 4 is a yet another flowchart for the method of forming
a combustion turbine component in accordance with the present
invention.
[0028] FIG. 5 is a cross sectional view of combustion turbine
component having a plurality of surface cooling features in
accordance with the present invention.
[0029] FIG. 6 is a greatly enlarged perspective view of the one of
the surface cooling features of the combustion turbine component of
FIG. 5.
[0030] FIG. 7 is a greatly enlarged perspective view of an
alternative embodiment of a surface cooling feature for a
combustion turbine component in accordance with the present
invention.
[0031] FIG. 8 is a greatly enlarged schematic cross sectional view
of yet another surface cooling feature for a combustion turbine
component in accordance with the present invention.
[0032] FIG. 9 is a greatly enlarged schematic cross sectional view
of still another surface cooling feature for a combustion turbine
component in accordance with the present invention.
[0033] FIG. 10 is a greatly enlarged schematic cross sectional view
of another surface cooling feature for a combustion turbine
component in accordance with the present invention.
[0034] FIG. 11 is a greatly enlarged cross schematic sectional view
of still another surface cooling feature for a combustion turbine
component in accordance with the present invention.
[0035] FIG. 12 is flowchart of a method of forming a combustion
turbine component having a plurality of surface cooling features in
accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout.
[0037] Referring initially to the flowchart 14 of FIG. 1, a first
embodiment of a method of making a combustion turbine component is
now described. After the start (Block 15), at Block 16 a plurality
of metallic combustion turbine subcomponent greenbodies are
assembled together to form a metallic greenbody assembly. The
metallic greenbody assembly has a shape closely resembling that of
the final combustion turbine component, but has a greater porosity,
a lesser density, and a larger size. The plurality of metallic
combustion turbine subcomponent greenbodies may be assembled by
conventional methods known to those of skill in the art.
[0038] Those of skill in the art will understand that a metallic
combustion turbine subcomponent greenbody is an unsintered metallic
combustion turbine subcomponent that lacks strength and has both a
low density and high porosity compared to a sintered metallic
body.
[0039] At Block 17, the metallic greenbody assembly is sintered to
thereby form the combustion turbine component. During sintering,
the metallic greenbody assembly may shrink in all directions by up
to 20%, thereby increasing in density. In addition, the porosity of
the metallic greenbody assembly is reduced and the strength of the
metallic greenbody assembly is increased.
[0040] The sintering may be solid state sintering or liquid state
sintering. During solid state sintering, the metallic greenbody
assembly is heated to a temperature below the melting point of its
constituents and held at that temperature until its particles
adhere to each other. During liquid state sintering, the metallic
greenbody assembly is heated until at least one but not all of its
constituents melt and reach a liquid state.
[0041] The metallic greenbody assembly may be placed under pressure
during the sintering. In this case, the sintering may comprise hot
isostatic pressing (HIP). HIP subjects a component to high gas
pressure in a containment vessel. The pressurizing gas is
preferably argon, although other inert gasses may be used as will
be appreciated by those of skill in the art. The pressurizing gas
is preferably applied between 100 and 310 MPa (15,000 p.s.i. and
45,000 p.s.i.) at a temperature of 480.degree. C. to 2000.degree.
C., although other pressures and other temperatures may be used as
well. As the containment vessel is heated during the HIP, the
pressure inside increases. The pressure is isostatic because it is
applied to the metallic greenbody assembly from all directions
evenly. The pressure and heat during HIP helps to reduce internal
voids in the metallic greenbody assembly through a combination of
plastic deformation, creep, and diffusion bonding, thus increasing
the density of the metallic greenbody assembly. Alternatively, the
sintering may be performed without the metallic greenbody assembly
being placed under pressure. Block 18 indicates the end of the
method.
[0042] After sintering, a bond coating may be formed on the
combustion turbine component and a thermal barrier coating may be
formed on the bond coating. Any number of exemplary bond coatings
and thermal barrier coatings known to those of skill in the art may
be used. In addition, the thermal barrier coating may be formed
directly on the combustion turbine component, without an
intervening bond coating. Additionally or alternatively, a wear
resistant layer may be formed on the combustion turbine
component.
[0043] Those of skill in the art will understand that, in some
embodiments, after sintering the combustion turbine component may
be placed into a casting mold and that additional metallic layers
may therefore be formed around the combustion turbine component,
encasing it.
[0044] In addition, it should be understood that a plurality of
metallic combustion turbine subcomponent greenbodies may be
assembled to form a metallic greenbody assembly and that the
metallic greenbody assembly may be sintered to form a combustion
turbine subcomponent assembly. Multiple combustion turbine
subcomponent assemblies may be formed in this fashion and then
joined together by conventional methods, such as welding or
brazing, to form the combustion turbine component. The multiple
combustion turbine subcomponent assemblies may also be placed into
a casting mold and additional layers may be formed therearound to
form a combustion turbine component
[0045] Referring now to the flowchart 20 of FIG. 2, a more detailed
method of making a combustion turbine component is now described.
After the start (Block 21) at Block 22 a plurality of metallic
combustion turbine subcomponent greenbodies are formed by direct
metal fabrication (DMF).
[0046] Direct metal fabrication processes include (1) layered
powder build-up processes, such as selective laser sintering (SLS),
(2) processes using light energy to chemically change a material,
such as stereolithography (SLA), (3) deposition techniques that
selectively deposit either particles or thin laminates, such as
solid ground curing (SGC), laminated object manufacturing (LOM),
fused deposition modeling (FDM), and ballistic particle
manufacturing (BPM), and (4) powder metallurgy processes that
tightly compact a metal powder into a mold or die, such as metal
injection molding (MIM) or tomo lithographic molding. SLS, for
example, uses a high powered laser to fuse the particles of a metal
powder into a mass representing a desired three dimensional object,
one layer at a time.
[0047] The plurality of metallic combustion turbine subcomponent
greenbodies may be formed by any of the above DMF processes, or by
other processes known to those of skill in the art. In addition,
each of the plurality of metallic combustion turbine subcomponent
greenbodies may be formed by the same DMF process, or each may be
formed by different DMF processes. For example, it may be
advantageous for some of the metallic combustion turbine
subcomponent greenbodies to be formed by SLA while others are
formed by MIM.
[0048] Each of the plurality of metallic combustion turbine
subcomponent greenbodies in this embodiment may comprise an
activatable binder and at least one of an oxide dispersion
strengthened (ODS) alloy, an intermetallic compound, and a
refractory metal. Each of the plurality of metallic combustion
turbine subcomponent greenbodies may also comprise a Nickel based
superalloy and, optionally, at least one rare earth element. The
activatable binder may comprise a polymer or plastic binder, a
metallic mix including a melting point depressor, or another
suitable binder known to those of skill in the art. Intermetallic
compounds are solid phases containing two or more metallic
elements, optionally having one or more non-metallic elements.
Intermetallic phases form due to strong bonding between unlike
metal atoms, this results in an ordered crystal structure, whereby
the various atomic species occupy specific sublatice sites.
Intermetallic compounds may also include interstitial compounds
such as carbides and nitrides. Such intermetallic compounds offer
advantageous properties like high temperature resistance and
hardness. Refractory metals include tungsten, molybdenum, niobium,
tantalum, and rhenium, and are extraordinarily resistant to heat
and wear. The methods described herein allow the formation of
combustion turbine components from the above materials, whereas
conventional methods such as casting and forging may not. It should
be noted that the plurality of metallic combustion turbine
subcomponent greenbodies may be metallic and not contain any
ceramic.
[0049] At Block 23, the plurality of metallic combustion turbine
subcomponent greenbodies are assembled together to form a metallic
greenbody assembly. At Block 24, the activatable binder is
activated. The activatable binder may be activated by heating the
greenbody assembly, or may be activated by other suitable methods.
After activation, the activatable binder may optionally be cured
through the use of a chemical agent, ultraviolet radiation,
bombardment with an electron beam, or further heating. Furthermore,
the activatable binder may optionally be removed from the greenbody
assembly by a pre-sintering heat treating at a temperature of
400.degree. C. to 600.degree. C., or at other suitable
temperatures, or through the use of chemical agents. This
pre-sintering heat treating, in some embodiments, may increase the
density, decrease the porosity, and shrink the greenbody
assembly.
[0050] At Block 25, the metallic greenbody assembly is sintered to
thereby form the combustion turbine component. Block 26 indicates
the end of the method.
[0051] With reference to the flowchart 30 of FIG. 3, an alternative
embodiment of a method of making a combustion turbine component is
now described. After the start (Block 32), at Block 34, a plurality
of metallic combustion turbine subcomponent greenbodies is formed
by tomo lithographic molding. Tomo lithographic molding involves
the production of a master tool which is then used either directly
as a mold or die, or alternatively used to produce a secondary
consumable mold. To create the master tool, a series of layers are
fabricated with lithographic techniques. The layers are
micro-machined to add additional features and details, and are then
laminated together by brazing or epoxy bonding to form the master
tool. The master tool may then be used as a mold or die for
processes such as microcasting, microinjection molding, metal
injection molding, and powder injection molding.
[0052] It should be understood that the term tomo lithographic
molding as used hereinafter is to mean the use of a master tool
formed by tomo lithographic molding in conjunction with a suitable
process to form metallic combustion turbine subcomponent
greenbodies therefrom.
[0053] At Block 36, the plurality of metallic combustion turbine
subcomponent greenbodies is assembled together and an activatable
binder is positioned between adjacent ones of the plurality of
metallic combustion turbine subcomponent greenbodies to form a
metallic greenbody assembly. The activatable binder may be formed
from the same material as the plurality of metallic combustion
turbine subcomponent greenbodies that has been mixed with a
suitable binding agent, such as a polymer or plastic binder or a
melting point depressor, such as boron. Alternatively, the
activatable binder may be a metallic mix together with a melting
point depressor.
[0054] If the activatable binder includes a melting point
depressor, the sintering may be liquid state sintering and the
plurality of metallic combustion turbine subcomponent greenbodies
may bond together by transient liquid phase (TLP) bonding. If the
plurality of metallic combustion turbine subcomponent greenbodies
is to be bonded together by TLP bonding, the activatable binder
between each of the plurality of metallic combustion turbine
subcomponent greenbodies is considered to be a TLP forming layer.
The metallic greenbody assembly and thus the TLP forming layer are
then heat treated at a temperature higher than the melting point of
the TLP forming layer, but lower than the melting point of the
other constituents of the metallic greenbody assembly. Accordingly,
the TLP forming layer melts during the sintering.
[0055] As the temperature remains constant, the melting point
depressor diffuses from the TLP forming layer into each of the
plurality of metallic combustion turbine subcomponent greenbodies,
and molecules from each of the plurality of metallic combustion
turbine subcomponent greenbodies diffuse into the TLP layer. As a
result of this diffusion, the melting point of TLP layer increases
beyond the temperature of the heat treatment and the TLP layer, now
close in composition to the plurality of metallic combustion
turbine subcomponent greenbodies, resolidifies. The resulting
bonded region between each of the plurality of metallic combustion
turbine subcomponent greenbodies is thin and of a high
strength.
[0056] Those of skill in the art will appreciate that the
activatable binder may be positioned between certain adjacent ones
of the plurality of metallic combustion turbine subcomponent
greenbodies but not between other adjacent ones of the plurality of
metallic combustion turbine subcomponent greenbodies.
[0057] At Block 38, the activatable binder is activated. At Block
40, the metallic greenbody assembly is sintered to thereby form the
combustion turbine component. The combustion turbine component is
devoid of an interface between adjacent ones of the plurality of
metallic combustion turbine subcomponent greenbodies after
sintering. This lack of interfaces may provide the combustion
turbine component with increased strength and the metallurgical
properties throughout may be consistent. Block 42 indicates the end
of the method.
[0058] Another embodiment of a method of making a combustion
turbine component is now described with reference to the flowchart
50 of FIG. 4. After the start (Block 52), at Block 54 a plurality
of metallic combustion turbine subcomponent greenbodies is formed
by metal injection molding. Metal injection molding involves
injecting a metallic powder and a suitable binder into a mold, in
some situations with conventional plastic injection molding
machines and processes. The mold used with the metal injection
molding may be formed by tomo lithographic molding or may be formed
from other methods.
[0059] At least one of the plurality of metallic combustion turbine
subcomponent greenbodies is formed to have at least one internal
cooling passage. This internal cooling passage is formed to have a
plurality of internal surface features, each with a dimension less
than 200 .mu.m. As will be explained in detail below, this
plurality of internal surface features increases the internal
surface area of the cooling passages of the combustion turbine
component and therefore enhances its ability to transfer heat away
from itself. As will also be explained in detail below, each of the
plurality of internal surface features may take a variety of shapes
and may be either a projection or a recess.
[0060] Of course, those of skill in the art will recognize that, in
some applications, one of the metallic combustion turbine
subcomponent greenbodies need not have internal cooling passages.
In such applications, the surface features described herein may be
external cooling features.
[0061] At Block 56, the plurality of metallic combustion turbine
subcomponent greenbodies is assembled together to form a metallic
greenbody assembly. At Block 58, the metallic greenbody assembly is
sintered to thereby form the combustion turbine component. In this
embodiment, the combustion turbine component has interfaces between
adjacent ones of the plurality of metallic combustion turbine
subcomponent greenbodies. Block 60 indicates the end of the method.
Those of skill in the art will appreciate that, in some
applications, there may be an interface between certain adjacent
ones of the plurality of metallic combustion turbine subcomponent
greenbodies after sintering and no interface between other adjacent
ones of the plurality of metallic combustion turbine subcomponent
greenbodies after sintering.
[0062] With reference to FIGS. 5-6, a combustion turbine component
70 having a plurality of internal surface cooling features 72 is
now described. The combustion turbine component 70 comprises a
metallic body 71 to define at least a substrate for the combustion
turbine component, the metallic body having a plurality of internal
cooling passages 73. The internal cooling passages 73 each have an
internal surface portion 75.
[0063] The internal surface portion 75 defines a plurality of
coarse surface cooling features 74, each having a dimension greater
than 500 .mu.m. As perhaps best shown in FIG. 6, one of the
plurality of coarse surface cooling features 74 illustratively
comprises a three-tiered projection.
[0064] A plurality of fine surface cooling features 76 is on at
least one of plurality of coarse surface cooling features 74, each
having a dimension less than 200 .mu.m. As also shown in FIG. 6,
the plurality of fine surface cooling features 76 illustratively
comprises convex or hemispherical projections, and may be on the
order of 50 .mu.m, for example.
[0065] The surface cooling features described herein increase the
surface area of the internal surface portion 75 of the combustion
turbine component 70, thereby enhancing its ability to transfer
heat away from itself and cool itself and into a cooling fluid
flowing therethrough. This enhanced heat transfer may allow for the
size of the cooling passageways 73 to be decreased compared to
those of conventional combustion turbine components. Furthermore,
this enhanced heat transfer may allow for an amount of cooling
fluid used to cool the combustion turbine component 70 to be
reduced.
[0066] A first additional surface cooling feature 77 comprising an
"x" shaped projection is illustratively on the coarse surface
cooling feature 74 and has a dimension greater than 200 .mu.m. It
should be understood that, although one first additional cooling
feature 77 is shown, there may instead be a plurality of first
additional surface cooling features on at least one of the
plurality of coarse surface cooling features 74 and that ones of
this plurality of first additional surface cooling features may be
of sizes both greater than and less than 200 .mu.m.
[0067] A second additional surface cooling feature 78 comprising a
circular-base pin and having a dimension less than 200 .mu.m is
illustratively on the first additional surface cooling feature
77.
[0068] Those of skill in the art will recognize that there may be
any number of stacked pluralities of surface cooling features (e.g.
there may be a third plurality of additional surface cooling
features on the second plurality of additional surface cooling
features, and so on and so forth)
[0069] Each of the plurality of coarse surface cooling features 74,
plurality of fine surface cooling features 76, first additional
plurality of surface cooling features 77, and second additional
plurality of surface cooling features 78 may be projections of
other suitable shapes, including but not limited to square-base
pins, circular-base pins, square-base pyramids, circular base
cones, tapered pins, polygonal-based pyramids, conical frustums,
pyramidical frustums, convex cones, serpentine ribs, hemispheres,
and combinations thereof. Each of the plurality of coarse surface
cooling features 74, plurality of fine surface cooling features 76,
first additional plurality of surface cooling features 77, and
second additional plurality of surface cooling features 78 may also
be recesses of various shapes, including but not limited to concave
cones, dimples, concave hemispheres, serpentine ribs, square shaped
recesses, circular shaped pin recesses, and combinations thereof.
Each of the plurality of coarse surface cooling features 74,
plurality of fine surface cooling features 76, first additional
plurality of surface cooling features 77, and second additional
plurality of surface cooling features 78 may have the same shape,
or each may have a different shape. For example, one of the
plurality of fine surface cooling features 76 may be a convex
hemispherical projection while another of the plurality of fine
surface cooling features may be a concave square shaped recess.
[0070] The metallic combustion turbine component body 70 may
comprise at least one of an oxide dispersion strengthened (ODS)
alloy, an intermetallic compound, and a refractory metal.
Advantages of construction from these materials are explained
above. In addition, the metallic body 71 may comprise a plurality
of metallic combustion turbine subcomponent bodies bonded together,
or a plurality of metallic combustion turbine subcomponent
greenbodies bonded together, by methods described in detail
above.
[0071] An alternative embodiment of the surface cooling features in
accordance with the present invention will now be described with
reference to FIG. 7. One of a plurality of coarse surface cooling
features 82 comprising a rectangular projection has a dimension
greater than 500 .mu.m, and a plurality of fine surface cooling
features 86 comprising rectangular projections and having at least
one dimension less than 200 .mu.m is illustratively thereon. A
first plurality of additional surface cooling features 84
comprising convex hemispheres and having at least one dimension
less than 200 .mu.m, such as less than 50 .mu.m, is on the
plurality of fine surface cooling features 86.
[0072] Various embodiments of the such surface cooling features in
accordance with the present invention will now be described with
reference to FIGS. 8-11. Referring first to FIG. 8, an internal
surface portion of a cooling passage of an combustion turbine
component 88 defines a plurality of coarse surface cooling features
90 comprising rectangular projections having a dimension, in this
instance the width, that is greater than 500 .mu.m. A plurality of
fine surface cooling features 92 comprising hemispherical
projections and having a dimension, in this instance a diameter,
that is less than 200 .mu.m is on the plurality of coarse surface
cooling features 90.
[0073] Referring now to FIG. 9, an internal surface portion of a
cooling passage of a combustion turbine component 94 defines a
plurality of coarse surface cooling features 96 comprising
rectangular recesses having a dimension greater than 500 .mu.m. A
plurality of fine surface cooling features 98 comprising concave
hemispherical recesses having a dimension less than 200 .mu.m is
defined in the plurality of coarse surface cooling features 98.
[0074] Illustrated in FIG. 10 is an internal surface portion of a
cooling passage of an combustion turbine component 100 defining a
plurality of coarse surface cooling features 102 comprising
rectangular projections having a dimension greater than 500 .mu.m.
A plurality of fine surface cooling features 104 comprising concave
hemispherical recesses having a dimension less than 200 .mu.m is
defined in the plurality of coarse surface cooling features
102.
[0075] Now referring to FIG. 11, an internal surface portion of a
cooling passage of a combustion turbine component 106 defines a
plurality of coarse surface cooling features 108 comprising
rectangular recesses having a dimension greater than 500 .mu.m. A
plurality of fine surface cooling features 110 comprising convex
hemispheres and having a dimension less than 200 .mu.m is on the
plurality of coarse surface cooling features 108.
[0076] A method of making a combustion turbine component having a
plurality of surface cooling features is now described. The method
includes forming a metallic combustion turbine component body by
direct metal fabrication (DMF). The metallic combustion turbine
component body is formed to have at least one surface portion
defining a plurality of coarse surface cooling features each having
a first dimension. The metallic combustion turbine component body
is also formed to have at least one fine cooling feature on at
least one of the first plurality of surface cooling features and
having a second dimension less than 200 .mu.m.
[0077] The first dimension may be greater than 500 .mu.m. There may
be a plurality of fine surface cooling features on one of the
plurality of coarse surface cooling features, or there may be a
plurality of fine surface cooling features on each of the plurality
of coarse surface cooling features.
[0078] The at least one fine surface cooling feature may comprise a
projection or a convex projection. Alternatively, the at least one
fine surface cooling feature may comprise a recess or a concave
recess. If there are a plurality of fine surface cooling features,
each of the plurality of fine surface cooling features may comprise
the same shape, or may comprise different shapes (e.g. one of the
plurality of fine surface cooling features may comprise a convex
projection while another of the plurality of fine surface cooling
features may comprise a concave recess).
[0079] One of the plurality of coarse surface cooling features may
comprise a projection or a convex projection. In addition, one of
the plurality of coarse surface cooling features may comprise a
recess or a concave recess. Each of the plurality of coarse cooling
features may be the same shape or each may be a different
shape.
[0080] Additional details of the plurality of coarse surface
cooling features and the at least one fine surface cooling feature
may be found above. The DMF may comprise tomo lithographic molding
or metal injection molding, details of which may also be found
above.
[0081] The metallic body may comprise at least one of an oxide
dispersion strengthened (ODS) alloy, an intermetallic compound, and
a refractory metal. Advantageous properties of these materials are
discussed above. The metallic body may additionally or
alternatively comprise a nickel based superalloy and, optionally,
at least one rare earth element.
[0082] With reference to the flowchart 120 of FIG. 12, a more
detailed method of forming a combustion turbine component having
surface cooling features is now described. After the start (Block
122), at Block 124 a plurality of metallic combustion turbine
subcomponent greenbodies are formed by direct metal fabrication
(DMF). At least one of the plurality of metallic combustion turbine
subcomponent greenbodies is formed to have at least one surface
portion defining a plurality of coarse surface cooling features
each having a first dimension. In addition, the at least one of the
plurality of metallic combustion turbine subcomponent greenbodies
is formed to have at least one fine surface cooling feature on at
least one of the plurality of coarse surface cooling features and
having a dimension less than the first dimension and less than 200
.mu.m.
[0083] The plurality of metallic combustion turbine subcomponent
greenbodies may comprise an activatable binder. The activatable
binder may be activated prior to sintering.
[0084] At Block 126, the plurality of metallic combustion turbine
subcomponent greenbodies are assembled together to form a metallic
greenbody assembly. At Block 128, the metallic greenbody assembly
is sintered to thereby form the metallic body. Block 130 indicates
the end of the method. Further details of assembling and sintering
may be found above.
[0085] Many modifications and other embodiments of the invention
will come to the mind of one skilled in the art having the benefit
of the teachings presented in the foregoing descriptions and the
associated drawings. Therefore, it is understood that the invention
is not to be limited to the specific embodiments disclosed, and
that modifications and embodiments are intended to be included
within the scope of the appended claims.
* * * * *