U.S. patent application number 15/219965 was filed with the patent office on 2016-11-17 for method for forming a directionally solidified replacement body for a component using additive manufacturing.
The applicant listed for this patent is United Technologies Corporation. Invention is credited to JinQuan Xu.
Application Number | 20160332266 15/219965 |
Document ID | / |
Family ID | 53174855 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160332266 |
Kind Code |
A1 |
Xu; JinQuan |
November 17, 2016 |
METHOD FOR FORMING A DIRECTIONALLY SOLIDIFIED REPLACEMENT BODY FOR
A COMPONENT USING ADDITIVE MANUFACTURING
Abstract
A method of manufacturing a replacement body for a component is
provided. The method includes the steps of: a) additively
manufacturing a crucible for casting of the replacement body; b)
solidifying a metal material within the crucible to form a
directionally solidified microstructure within the replacement
body; and c) removing the crucible to reveal the directionally
solidified replacement body.
Inventors: |
Xu; JinQuan; (East
Greenwich, RI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corporation |
Farmington |
CT |
US |
|
|
Family ID: |
53174855 |
Appl. No.: |
15/219965 |
Filed: |
July 26, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14706685 |
May 7, 2015 |
9452474 |
|
|
15219965 |
|
|
|
|
61991097 |
May 9, 2014 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22D 25/02 20130101;
B22F 3/1055 20130101; B22F 5/04 20130101; F05D 2230/235 20130101;
B23K 2101/001 20180801; F02C 7/222 20130101; F05D 2260/202
20130101; F05D 2230/238 20130101; B22C 9/108 20130101; F01D 5/186
20130101; F05D 2230/30 20130101; B23P 6/045 20130101; B22C 9/04
20130101; F05D 2220/32 20130101; B22D 29/001 20130101; C30B 21/02
20130101; Y02P 10/292 20151101; B33Y 80/00 20141201; F05D 2230/234
20130101; B22C 9/12 20130101; F05D 2240/122 20130101; C30B 11/003
20130101; F05D 2300/606 20130101; B22F 5/009 20130101; B23K 15/0046
20130101; F01D 5/005 20130101; B22C 9/02 20130101; B23K 15/0086
20130101; B23K 26/342 20151001; F05D 2230/80 20130101; F05D
2300/175 20130101; B23K 9/04 20130101; B22D 23/06 20130101; B22F
3/24 20130101; C30B 11/00 20130101; C30B 29/52 20130101; B22F
2998/10 20130101; B33Y 40/00 20141201; F01D 5/187 20130101; B23K
37/00 20130101; B33Y 10/00 20141201; F23R 3/002 20130101; B22F
2003/248 20130101; B23K 26/70 20151001; F05D 2230/233 20130101;
Y02P 10/295 20151101; B23P 6/007 20130101; F01D 5/12 20130101; B23K
9/167 20130101; F05D 2300/20 20130101; B23K 1/0018 20130101; B23K
31/02 20130101; F05D 2300/608 20130101; F01D 9/04 20130101; B23P
6/005 20130101; B23K 20/00 20130101; B22C 9/10 20130101; B22C 9/22
20130101; B22D 27/045 20130101; F01D 5/18 20130101; F05D 2260/204
20130101; Y02P 10/25 20151101; F05D 2240/304 20130101; B22F 5/007
20130101; B23K 26/34 20130101; F05D 2230/21 20130101 |
International
Class: |
B23P 6/00 20060101
B23P006/00; B23K 9/167 20060101 B23K009/167; B23K 15/00 20060101
B23K015/00; B23K 20/00 20060101 B23K020/00; F01D 5/18 20060101
F01D005/18; B33Y 80/00 20060101 B33Y080/00; B33Y 10/00 20060101
B33Y010/00; B22D 27/04 20060101 B22D027/04; B23P 6/04 20060101
B23P006/04; B23K 1/00 20060101 B23K001/00; B23K 37/00 20060101
B23K037/00 |
Claims
1. A method of manufacturing a replacement body for a component,
comprising: additively manufacturing a crucible for casting of the
replacement body; solidifying a metal material within the crucible
to form a directionally solidified microstructure within the
replacement body; and removing the crucible to reveal the
directionally solidified replacement body.
2. The method of claim 1, wherein the step of solidifying the metal
material includes directionally solidifying the material to have a
single crystal microstructure.
3. The method of claim 1, wherein the step of solidifying the metal
material includes directionally solidifying the material to have a
columnar grain microstructure.
4. The method of claim 1, wherein the metal material is selected
from the group consisting of a nickel based superalloy, cobalt
based superalloy, iron based superalloy, and mixtures thereof.
5. The method of claim 1, wherein the crucible is additively
manufactured of at least one of a ceramic material or a refractory
metal material.
6. The method of claim 1, further comprising the step of adding the
metal material in powder form to the crucible.
7. The method of claim 1, wherein the crucible includes a core at
least partially within a shell, the core at least partially defines
at least one internal passageway within the replacement body.
8. The method of claim 7, further comprising forming the core via
additive manufacturing.
9. The method of claim 7, further comprising forming the shell via
additive manufacturing.
10. A method for repairing a component, comprising the steps of:
identifying a target section of the component; removing the target
section from the component, thereby creating a void in the
component; additively manufacturing a crucible for casting of a
replacement body; solidifying a metal material within the crucible
to form a directionally solidified microstructure within the
replacement body; removing the crucible to reveal the directionally
solidified replacement body; and bonding the replacement body into
the void within the component.
11. The method of claim 10, wherein the step of solidifying the
metal material includes directionally solidifying the material to
have a single crystal microstructure.
12. The method of claim 10, wherein the step of solidifying the
metal material includes directionally solidifying the material to
have a columnar grain microstructure.
13. The method of claim 10, wherein the step of bonding includes
laser welding, Gas tungsten arc welding (GTAW), Electron beam
welding (EBW), soldering, transition liquid phase bonding and
combinations thereof.
Description
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/706,685 filed May 7, 2015, which claims priority to
U.S. Patent Appln. No. 61/991,097 filed May 9, 2014.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present disclosure relates to components for a gas
turbine engine and, more particularly, to the additive manufacture
thereof.
[0004] 2. Background Information
[0005] Gas turbine engines typically include a compressor section
to pressurize airflow, a combustor section to burn a hydrocarbon
fuel in the presence of the pressurized air, and a turbine section
to extract energy from the resultant combustion gases.
[0006] In the gas turbine industry, methods for fabricating
components with internal passageways, such as blades and vanes
within the turbine section, using additive manufacturing invite
much attention. Since a component is produced in a continuous
process in an additive manufacturing operation, features associated
with conventional manufacturing processes such as machining,
forging, welding, casting, etc. can be eliminated leading to
savings in cost, material, and time.
[0007] An inherent feature of metallic components fabricated by
additive manufacturing is that the metallic material forming the
component has a polycrystalline microstructure. However, for
numerous types of turbine components it is preferable to use a
metallic material having a single crystal, or a columnar grain
microstructure, which microstructure is able to withstand the
higher temperatures and stresses typically experienced in the
operating environment in a hot gas stream.
SUMMARY
[0008] According to an aspect of the present disclosure, a method
of manufacturing a replacement body for a component is provided.
The method includes the steps of: a) additively manufacturing a
crucible for casting of the replacement body; b) solidifying a
metal material within the crucible to form a directionally
solidified microstructure within the replacement body; and c)
removing the crucible to reveal the directionally solidified
replacement body.
[0009] In a further embodiment of the present disclosure, the step
of solidifying the metal material includes directionally
solidifying the material to have a single crystal
microstructure.
[0010] In a further embodiment of the present disclosure, the step
of solidifying the metal material includes directionally
solidifying the material to have a columnar grain
microstructure.
[0011] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the metal material may include a nickel
based superalloy, cobalt based superalloy, iron based superalloy,
and mixtures thereof.
[0012] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the crucible is additively manufactured
of at least one of a ceramic material or a refractory metal
material.
[0013] A further embodiment of any of the foregoing embodiments of
the present disclosure includes the step of adding the metal
material in powder form to the crucible.
[0014] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the crucible includes a core at least
partially within a shell, and the core at least partially defines
at least one internal passageway within the replacement body.
[0015] A further embodiment of any of the foregoing embodiments of
the present disclosure includes forming the core via additive
manufacturing.
[0016] A further embodiment of any of the foregoing embodiments of
the present disclosure includes forming the shell via additive
manufacturing.
[0017] According to another aspect of the present invention, a
method of manufacturing a replacement body for a component is
provided. The method includes the steps of: a) additively
manufacturing the replacement body with a metal material; b)
additively manufacturing a core at least partially within the
replacement body; c) at least partially encasing the replacement
body and the core within a shell; d) melting the additively
manufactured replacement body; e) solidifying the metal material of
the additively manufactured replacement body to form a
directionally solidified microstructure within the component; and
1) removing the shell and the core to reveal the directionally
solidified microstructure replacement body.
[0018] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the step of solidifying the metal
material includes directionally solidifying the material to have a
single crystal microstructure.
[0019] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the step of solidifying the metal
material includes directionally solidifying the material to have a
columnar grain microstructure.
[0020] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the metal material is a powder.
[0021] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the core at least partially defines at
least one internal passageway within the replacement body.
[0022] A further embodiment of any of the foregoing embodiments of
the present disclosure includes the step of concurrently additively
manufacturing the replacement body and the core within the
replacement body.
[0023] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the core at least partially defines at
least one microchannel within the replacement body.
[0024] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the microchannel is additively
manufactured of a refractory material and the internal passageway
is additively manufactured of a ceramic material.
[0025] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the additive manufacturing is performed
by a multi-powder bed system.
[0026] A further embodiment of any of the foregoing embodiments of
the present disclosure includes the step of applying a wax material
at least partially onto the replacement body.
[0027] According to another aspect of the present disclosure, a
method for repairing a component is provided that includes the
steps of: a) identifying a target section of the component; b)
removing the target section from the component, thereby creating a
void in the component; c) additively manufacturing a crucible for
casting of a replacement body; d) solidifying a metal material
within the crucible to form a directionally solidified
microstructure within the replacement body; e) removing the
crucible to reveal the directionally solidified replacement body;
and f) bonding the replacement body into the void within the
component.
[0028] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the step of solidifying the metal
material includes directionally solidifying the material to have a
single crystal microstructure.
[0029] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the step of solidifying the metal
material includes directionally solidifying the material to have a
columnar grain microstructure.
[0030] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the step of bonding includes laser
welding, Gas tungsten arc welding (GTAW), Electron beam welding
(EBW), soldering, transition liquid phase bonding and combinations
thereof.
[0031] According to another aspect of the present disclosure, a
component for a gas turbine engine is provided. The component
includes a metal single crystal material microstructure and a
replacement body bonded into the component. The replacement body is
additively manufactured, and solidified to have a directionally
solidified microstructure the same as the microstructure of the
component.
[0032] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the replacement body has a metal single
crystal microstructure.
[0033] In a further embodiment of any of the foregoing embodiments
of the present disclosure, the replacement body has a metal
columnar grain microstructure.
[0034] The foregoing features and elements may be combined in
various combinations without exclusivity, unless expressly
indicated otherwise. These features and elements as well as the
operation thereof will become more apparent in light of the
following description and the accompanying drawings. It should be
understood, however, the following description and drawings are
intended to be exemplary in nature and non-limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Various features will become apparent to those skilled in
the art from the following detailed description of the disclosed
non-limiting embodiment. The drawings that accompany the detailed
description can be briefly described as follows.
[0036] FIG. 1 is a diagrammatic cross-section of an example of gas
turbine engine architecture.
[0037] FIG. 2 is a diagrammatic cross-section of another example of
gas turbine engine architecture.
[0038] FIG. 3 is an enlarged diagrammatic cross-section of an
engine turbine section.
[0039] FIG. 4 is a perspective view of a turbine blade as an
example component with internal passages.
[0040] FIG. 5 is a diagrammatic cross-section view of a turbine
blade showing internal passages.
[0041] FIG. 6A is a diagrammatic perspective view of a turbine
blade.
[0042] FIG. 6B is a diagrammatic perspective view of the turbine
blade shown in FIG. 6A, showing a target section removed from the
trailing edge.
[0043] FIG. 6C is a diagrammatic perspective view of the turbine
blade shown in FIG. 6A with a replacement body integrated into the
blade.
[0044] FIG. 7 is a diagrammatic lateral cross-section view of a
replacement body with internal passages disposed within the
crucible.
[0045] FIG. 8 is a flow chart of one disclosed non-limiting
embodiment of a method for fabricating replacement body with
internal passages.
[0046] FIG. 9 is a flow chart of one disclosed non-limiting
embodiment of a method for fabricating replacement body with
internal passages.
[0047] FIG. 10 is a diagrammatic lateral cross-section view of a
replacement body with internal passages disposed within the
crucible.
[0048] FIG. 11 is a flow chart of another disclosed non-limiting
embodiment of a method for fabricating a replacement body with
internal passages.
[0049] FIG. 12 is a diagrammatic lateral cross-section view of a
replacement body with internal passages and a microcircuit passage
disposed within the crucible.
[0050] FIG. 13 is a diagrammatic perspective sectional view of a
microcircuit cooling passage disposed within an airfoil wall.
[0051] FIG. 14 is a flow chart of another disclosed non-limiting
embodiment of a method for fabricating component replacement body
with internal passages.
[0052] FIG. 15 is a diagrammatic perspective sectional view of a
replacement body including internal passages and a microcircuit
cooling passage disposed within an airfoil wall.
[0053] FIG. 16 is a flow chart of another disclosed non-limiting
embodiment of a method for fabricating component replacement body
with internal passages.
[0054] FIG. 17 is a diagrammatic perspective sectional view of a
replacement body having a microcircuit cooling passage disposed
within an airfoil wall.
[0055] FIG. 18 is a flow chart of another disclosed non-limiting
embodiment of a method for fabricating an example component with
internal passages.
[0056] FIG. 19 is a diagrammatic perspective sectional view of a
microcircuit cooling passage disposed within an airfoil wall.
[0057] FIG. 20 is a flow chart of another disclosed non-limiting
embodiment of a method for repairing or modifying a component with
a replacement body, which replacement body is additively
manufactured with a directionally solidified microstructure.
DETAILED DESCRIPTION
[0058] FIG. 1 schematically illustrates a gas turbine engine 20.
The gas turbine engine 20 is disclosed herein as a two-spool turbo
fan that generally incorporates a fan section 22, a compressor
section 24, a combustor section 26 and a turbine section 28.
Alternative engine architectures 200 might include an augmentor
section 12, an exhaust duct section 14 and a nozzle section 16
(FIG. 2) among other systems or features. The fan section 22 drives
air along both a bypass flowpath and into the compressor section
24. The compressor section 24 drives air along a core flowpath for
compression and communication into the combustor section 26 then
expansion through the turbine section 28. Although depicted as a
turbofan in the disclosed non-limiting embodiment, it should be
understood that the concepts described herein are not limited to
use with turbofans as the teachings may be applied to other types
of turbine engine architectures such as turbojets, turboshafts, and
three-spool (plus fan) turbofans.
[0059] The engine 20 generally includes a low spool 30 and a high
spool 32 mounted for rotation about an engine central longitudinal
axis X relative to an engine static structure 36 via several
bearing structures 38. The low spool 30 generally includes an inner
shaft 40 that interconnects a fan 42, a low pressure compressor
("LPC") 44 and a low pressure turbine ("LPT") 46. The inner shaft
40 drives the fan 42 directly or through a geared architecture 48
to drive the fan 42 at a lower speed than the low spool 30. An
exemplary reduction transmission is an epicyclic transmission,
namely a planetary or star gear system.
[0060] The high spool 32 includes an outer shaft 50 that
interconnects a high pressure compressor ("HPC") 52 and high
pressure turbine ("HPT") 54. A combustor 56 is arranged between the
high pressure compressor 52 and the high pressure turbine 54. The
inner shaft 40 and the outer shaft 50 are concentric and rotate
about the engine central longitudinal axis "A" which is collinear
with their longitudinal axes.
[0061] Core airflow is compressed by the LPC 44 then the HPC 52,
mixed with the fuel and burned in the combustor 56, then expanded
over the HPT 54 and the LPT 46. The turbines 54, 46 rotationally
drive the respective low spool 30 and high spool 32 in response to
the expansion. The main engine shafts 40, 50 are supported at a
plurality of points by bearing structures 38 within the static
structure 36. Bearing structures 38 at various locations may
alternatively or additionally be provided.
[0062] With reference to FIG. 3, an enlarged schematic view of a
portion of the turbine section 28 is shown by way of example;
however, other engine sections will also benefit here from. A full
ring shroud assembly 60 within the engine case structure 36
supports a blade outer air seal (BOAS) assembly 62 with a multiple
of BOAS segments 64 proximate to a rotor assembly 66 (one
schematically shown).
[0063] The full ring shroud assembly 60 and the blade outer air
seal (BOAS) assembly 62 are axially disposed between a forward
stationary vane ring 68 and an aft stationary vane ring 70. Each
vane ring 68, 70 includes an array of vanes 72, 74 that extend
between a respective inner vane support 76, 78 and an outer vane
support 80, 82. The outer vane supports 80, 82 are attached to the
engine case structure 36.
[0064] The rotor assembly 66 includes an array of blades 84
circumferentially disposed around a disk 86. Each blade 84 includes
a root 88, a platform 90 and an airfoil 92 (also shown in FIG. 4).
A portion of each blade root 88 is received within a rim 94 of the
disk 86. Each airfoil 92 extends radially outward, and has a tip 96
disposed in close proximity to a blade outer air seal (BOAS)
assembly 62. Each BOAS segment 64 may include an abradable material
to accommodate potential interaction with the rotating blade tips
96.
[0065] To resist the high temperature stress environment in the hot
gas path of a turbine engine, each blade 84 may be formed to have a
single crystal microstructure. It should be appreciated that
although a blade 84 with internal passageways 98 (FIG. 5) will be
described and illustrated in detail, other components including,
but not limited to, vanes, fuel nozzles, airflow swirlers,
combustor liners, turbine shrouds, vane endwalls, airfoil edges and
other gas turbine engine components "W" may also be manufactured in
accordance with the teachings herein.
[0066] The present disclosure involves the use of additive
manufacturing techniques to form a portion of a component "W",
which portion will be referred to hereinafter as a "replacement
body". The manufacture of replacement bodies and component repairs
with such replacement bodies according to the present disclosure
will be disclosed in the embodiments described below. In general
terms, additive manufacturing techniques allow for the creation of
a replacement body for a component "W" by building the replacement
body with successively added layers; e.g., layers of powdered
material. The additive manufacturing process facilitates
manufacture of relatively complex replacement bodies. In the
additive manufacturing process, one or more materials are deposited
on a surface in a layer. In some instances, the layers are
subsequently compacted. The material(s) of the layer may be
subsequently unified using any one of a number of known processes
(e.g., laser, electron beam, etc.). Typically, the deposition of
the material (i.e. the geometry of the deposition layer for each of
the materials) is computer controlled using a three-dimensional
computer aided design (CAD) model. The three-dimensional (3D) model
is converted into a plurality of slices, with each slice defining a
cross section of the replacement body for a predetermined height
(i.e. layer) of the 3D model. The additively manufactured
replacement body is then "grown" layer by layer; e.g., a layer of
powdered material(s) is deposited and then unified, and then the
process is repeated for the next layer. Examples of additive
manufacturing processes that can be used with the present
disclosure include, but are not limited to, Stereolithography
(SLS), Direct Selective Laser Sintering (DSLS), Electron Beam
Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net
Shaping (LENS), Laser Net Shape Manufacturing (LNSM), Direct Metal
Deposition (DMD), Direct Metal Laser Sintering (DMLS) and others.
The present disclosure is not limited to using any particular type
of additive manufacturing process.
[0067] In the embodiments described below, an additive
manufacturing process is for manufacturing a replacement body for a
component "W". For purposes of illustrating the present disclosure,
the component will be described and shown in terms of a turbine
blade 84 and a replacement body 99 portion of the turbine blade 84.
The present disclosure is not limited to this example. As can be
seen in FIGS. 6A-6C and explained below, a target section 93 of
blade (e.g., the dashed line portion containing damage shown in
FIG. 6A) located at the trailing edge of the airfoil 92 portion of
the blade is identified and removed (i.e., FIG. 6B diagrammatically
shows the void remaining after target section 93 is removed). A
replacement body 99 is produced according to the present
disclosure, and is subsequently integrated (e.g., bonded) to the
blade 84 in the void left upon removal of the target section 93
(e.g., shown in dashed lines in FIG. 6C). The descriptions below
regarding the different embodiments for forming the replacement
body 99 will, therefore, be shown in the Figures as a portion of
the trailing edge of the blade airfoil. To further illustrate the
present disclosure, a microcircuit cooling passage 144 that may be
disposed in the wall of an airfoil is also discussed. An example of
a microcircuit cooling passage is disclosed in U.S. Pat. No.
6,247,896, which patent is hereby incorporated by reference in its
entirety.
[0068] Now referring to FIGS. 7 and 8, a replacement body 99 (e.g.,
a portion of a turbine blade trailing edge) is shown disposed
within a crucible 100. The additive manufactured crucible 100
generally includes a core 102 and a shell 104. The shell 104 and
the core 102 define the geometry of the replacement body 99, and
provide a support structure for the replacement body 99 during
formation. The shell 104 forms a structure having surfaces that
will define outer surfaces of the replacement body 99. The core 102
forms solids that occupy volumes that will be voids (e.g., internal
passages) within the final replacement body 99. In some instances,
however, there may be no need for a core 102 when producing the
replacement body 99. For example, if a component "W" has a damaged
wall portion, and that wall portion has no internal void (e.g., no
cooling passages, etc.), then the additively manufactured crucible
may include only a shell 104 portion. In other instances, the
replacement body may again be a wall portion but in this case the
wall portion includes a plurality of cooling passages. Exemplary
methods for creating such cooling passages according to the present
disclosure are provided below. The crucible 100 may comprise a
variety of different material types; e.g., refractory metals,
ceramics, combinations thereof, etc. As will be explained below,
the crucible 100 may be utilized as a melting unit and/or a die
during processing of the replacement body.
[0069] With reference to FIG. 8, according to one disclosed
non-limiting embodiment for forming single crystal superalloy
component replacement body with internal passageways, a method
includes forming a crucible 100. The crucible 100 is additively
manufactured (Step 202). It should be appreciated that the core 102
and/or shell 104 of the crucible 100 may be additively manufactured
from materials that include, but are not limited to, ceramic
material such as silica, alumina, zircon, cobalt, mullite, kaolin,
refractory metals, combinations thereof, etc.
[0070] Following additive manufacture, the crucible 100 may be
dried and fired (i.e. bisqued) at an intermediate temperature
before high firing to fully sinter and densification. The
additively manufactured crucible 100 thereby forms a cavity for
forming the replacement body. That is, the crucible 100 is
integrally formed by the additive manufacturing process such that
the conventional separate manufacture of the core and shell are
essentially combined into a single step. It should be appreciated
that single or multiple molds and cavities may be additively
manufactured and assembled.
[0071] The crucible 100 may then be filled with a replacement body
material such as a desired metal (Step 204). Non-limiting examples
of replacement body materials include superalloys; e.g., nickel
based superalloys, cobalt based superalloys, iron based
superalloys, combinations thereof, etc. In some instances, the
replacement body material added to the crucible 100 may be in
powder form that can be subsequently melted. In other instances,
the replacement body material added to the crucible 100 may be in
molten form that is subsequently solidified. The present disclosure
is not limited, however, to adding replacement body material in any
particular form.
[0072] In some instances, the crucible is combined or utilized with
structure (e.g., a starter seed and a chill plate) operable to
cause the replacement body to be directionally solidified; e.g.,
formed to have a single crystal microstructure, a columnar grain
microstructure, or other type of directionally solidified
microstructure. A single crystal solid (sometimes referred to as a
"monocrystalline solid") replacement body is one in which the
crystal lattice of substantially all of the replacement body
material is continuous and unbroken to the edges of the replacement
body, with virtually no grain boundaries. Processes for growing a
single crystal alloy microstructure or a columnar grain
microstructure are believed to be known to those of ordinary skill
in the art, and therefore descriptions of such processes are not
necessary here for enablement purposes. However, an example is
provided hereinafter to facilitate understanding of the present
disclosure. A portion of a metallic starter seed may extend into a
vertically lower portion of the replacement body material receiving
portion of the crucible 100. During subsequent processing of the
replacement body, molten component material contacts the starter
seed and causes the partial melt back thereof. The replacement body
material is subsequently solidified by a thermal gradient moving
vertically through the crucible 100; e.g., the replacement body is
directionally solidified from the unmelted portion of the starter
seed to form the single crystal replacement body. The thermal
gradient used to solidify the replacement body may be produced by a
combination of mold heating and mold cooling; e.g., using a mold
heater, a mold cooling cone, a chill plate and withdrawal of the
component being formed. As indicated above, the aforesaid
description is an example of how a replacement body may be formed
with a single crystal microstructure, and the present disclosure is
not limited thereto.
[0073] Now referring again to the embodiment described in FIGS. 7
and 8, a single crystal starter seed or grain selector may be
utilized to create a replacement body 99 having a single crystal
microstructure during solidification (Step 206). The solidification
may utilize a chill block in a directional solidification furnace.
The directional solidification furnace has a hot zone that may be
induction heated and a cold zone separated by an isolation valve.
The chill block and additively manufactured crucible 100 may be
elevated into the hot zone and filled with molten super alloy.
After the pour, or being molten, the chill plate may descend into
the cold zone causing a solid/liquid interface to advance from the
partially molten starter seed, creating the desired single crystal
microstructure as the solid/liquid interface advances away from the
starter seed. The formation process may be performed within an
inert atmosphere or vacuum to preserve the purity of the
replacement body material being formed.
[0074] Following solidification, the additively manufactured
crucible 100 may be removed from the solidified replacement body 99
by various techniques (e.g., caustic leaching), thereby leaving
behind the finished single crystal replacement body 99 (Step 208).
After removal, the replacement body 99 may be further finished such
as by machining, threading, surface treating, coating or any other
desirable finishing operation (Step 210).
[0075] Now referring to FIGS. 9 and 10, in another non-limiting
embodiment a method 300 includes additively manufacturing a
replacement body 99 for a component "W" (e.g. a turbine blade,
vane, etc.) and a crucible 100. The replacement body 99 includes
internal cooling passages 101 (Step 302). In this embodiment, the
replacement body 99 and the crucible 100 are additively
manufactured using a multi-feedstock process such as a two-powder
bed system. The replacement body is manufactured of the desired
superalloy, while the core 102 and shell 104 of the crucible 100
are manufactured of a different material such as a ceramic, a
refractory metal, or other material which is later removed. With
respect to the internal cooling passages within the replacement
body, during the additive manufacturing process, a ceramic
material, a refractory metal material, or other core 102 material
is deposited at the locations within the layers of the additively
formed structure to coincide with the locations of the voids that
will form the passages within the replacement body. The core 102
within the replacement body and the shell 104 that surrounds the
replacement body are later removed; e.g., in a manner as described
above.
[0076] The replacement body, being additively manufactured, may be
a polycrystalline superalloy. As indicated above, it may be
desirable for the replacement body to have a single crystal
microstructure (or a columnar grain microstructure) that is better
suited to withstand the high temperature, high stress operating
environment of the gas turbine engine.
[0077] To thereby facilitate formation of a replacement body having
a single crystal microstructure, the additively manufactured
superalloy replacement body is re-melted within the crucible 100
(Step 304). For example, the additively manufactured superalloy
replacement body may be re-melted and directionally solidified
(e.g., as described above) to form a metal single crystal
microstructure within the crucible 100. As indicated above, the
present disclosure is not limited to any particular technique for
creating the single crystal microstructure.
[0078] Following solidification, the additively manufactured
crucible 100 may be removed from the solidified replacement body by
various known techniques (e.g., caustic leaching), to leave the
finished single crystal component (Step 306). After removal, the
replacement body may be further finished such as by machining,
threading, surface treating, coating or any other desirable
finishing operation (Step 308).
[0079] Now referring to FIGS. 11-13, a method 400 according to
another non-limiting embodiment includes additively manufacturing
the replacement body with a multi-feedstock additive manufacturing
process such as three-powder bed system (Step 402). The replacement
body is manufactured of the desired superalloy while the core 102
and shell 104 of the crucible 100 are manufactured of a different
material (FIG. 12). During the additive manufacturing process, a
ceramic material is deposited at the locations within the layers of
the additively formed structure to coincide with the locations of
the voids that will form the internal cooling passages within the
replacement body, and a refractory metal material is deposited at
the locations within the layers of the additively formed structure
to coincide with the locations of the voids that will form
microcircuits 144 (see FIG. 13) within the replacement body. As
indicated above, microcircuit cooling passages 144 may be disposed
in the wall 103 of an airfoil. FIG. 13 illustrates an example of a
microcircuit cooling passage, which microcircuit passage is shown
schematically disposed in the wall portion of the replacement body
shown in FIG. 12. The microcircuit(s) 144 is relatively smaller
than, and may be located outboard of, the internal cooling passages
101 to facilitate tailorable, high efficiency convective cooling.
Examples of refractory metal materials that can be additively
deposited to form the microcircuits include, but are not limited
to, molybdenum (Mo) and Tungsten (W), both of which possess
relatively high ductility for formation into complex shapes and
have melting points that are in excess of typical casting
temperatures of nickel based superalloys. Refractory metals of this
type can be removed by various known techniques (e.g., chemical
removal, thermal leaching, oxidation methods, etc.) to leave behind
the microcircuit 144 cavity.
[0080] As described above, to facilitate formation of a replacement
body having a single crystal microstructure, the additively
manufactured replacement body is re-melted within the crucible 100
(Step 404) formed in step 402, and subjected to processes for
creating the single crystal microstructure (or columnar grain
microstructure) within the replacement body 99. As indicated above,
the present disclosure is not limited to any particular technique
for creating the single crystal replacement body.
[0081] Following solidification, the additively manufactured
crucible 100 may be removed from the solidified replacement body by
various known techniques (e.g., caustic leaching) to leave the
finished single crystal replacement body 99 (Step 406). After
removal, the replacement body may be further finished such as by
machining, threading, surface treating, coating or any other
desirable finishing operation (Step 408).
[0082] Now referring to FIGS. 14 and 15, a method 500 according to
another disclosed non-limiting embodiment includes additively
manufacturing a replacement body with a multi-feedstock additive
manufacturing process such as two-powder bed system (Step 502).
During the additive manufacturing process, a desired superalloy
material is deposited in layers to form the replacement body
structure, and a refractory metal material is additively deposited
at locations within the layers of the additively formed structure
to coincide with the locations of the voids that will form the
microcircuits 144 (see also FIG. 13) within the replacement body
99.
[0083] In this embodiment, the internal cooling passages 101 of the
replacement body may be filled with ceramic slurry to form the core
102 (Step 504). The slurry may include, but is not limited to,
ceramic materials commonly used as core materials including, but
not limited to, silica, alumina, zircon, cobalt, mullite, and
kaolin. In the next step, the ceramic core may be cured in situ by
a suitable thermal process if necessary (Step 506).
[0084] Next, a ceramic shell 104 may then be formed over the
replacement body and internal ceramic core (Step 508). The ceramic
shell may be formed over the replacement body and ceramic core by
dipping the combined replacement body and ceramic core into a
ceramic powder and binder slurry to form a layer of ceramic
material covering the replacement body and core. The slurry layer
is dried and the process repeated for as many times as necessary to
form a green (i.e. unfired) ceramic shell mold. The thickness of
the green ceramic shell mold at this step may be from about 0.2-1.3
inches (5-32 mm) The green shell mold may then be bisque fired at
an intermediate temperature to partially sinter the ceramic and
burn off the binder material. The mold may then be high fired at a
temperature between about 1200.degree. F. (649.degree. C.) to about
1800.degree. F. (982.degree. C.) from about 10 to about 120 minutes
to sinter the ceramic to full density to form the shell mold.
[0085] As described above, to facilitate formation of a replacement
body 99 having a single crystal microstructure, the additively
manufactured component is re-melted within the crucible 100 (Step
510), and subjected to processes for creating the single crystal
microstructure (or columnar grain microstructure) within the
replacement body. As indicated above, the present disclosure is not
limited to any particular technique for creating the single crystal
microstructure.
[0086] Following solidification, the additively manufactured
crucible 100 may be removed from the solidified replacement body by
known techniques (e.g., caustic leaching, etc.), to leave the
finished single crystal replacement body 99 (Step 512). After
removal, the replacement body 99 may be further finished such as by
machining, threading, surface treating, coating or any other
desirable finishing operation (Step 514).
[0087] Now referring to FIGS. 16 and 17, a method 600 according to
another disclosed non-limiting embodiment facilitates a high
quality surface finish. As described above, the replacement body is
additively manufactured of a desired superalloy that itself forms
the cavity pattern for the crucible. The additively manufactured
replacement body is then re-melted within the crucible to
facilitate formation of the single crystal microstructure. However,
the crucible, being formed by the additive manufactured structure,
may have a relatively rough surface finish typically not acceptable
for use as a blade or vane in the gas turbine engine; e.g.,
blade/vane airfoil surfaces typically require relatively tight
contour tolerances and smooth surface finishes that may not be
achievable by direct additive manufacture within a reasonable cycle
time.
[0088] To further improve the finish of an exterior surface of a
replacement body 99 (additively manufactured according to any of
the above-described embodiments), a relatively thin layer of a wax
material 166 may be applied to an external, aerodynamic surface
(e.g. an airfoil surface) of the replacement body 99 (Step 604;
FIG. 17). The wax material provides a smoother surface finish than
the relatively rough surface of an additively manufactured
replacement body 99.
[0089] Next, a ceramic shell 104 is formed over the replacement
body 99 (Step 606). The ceramic shell may be formed over the
additively manufactured body 99 by dipping or other process.
[0090] The relatively thin layer of a wax material 166 is
subsequently removed (Step 608). The relatively thin layer of a wax
material 166 may be removed by heating or other operation that does
not otherwise affect the additively manufactured replacement body
99.
[0091] Then, as described above, to facilitate formation of the
single crystal microstructure (or columnar grain microstructure)
the additively manufactured superalloy replacement body 99 is
re-melted within the shell of the crucible (Step 610), and
subjected to processes for creating the single crystal
microstructure within the replacement body 99. As indicated above,
the present disclosure is not limited to any particular technique
for creating the single crystal microstructure. It should be
further appreciated that the re-melting (Step 610) may
alternatively be combined with the removal of the relatively thin
layer of a wax material 166 (Step 608).
[0092] Following solidification, the solidified replacement body
may be removed from the crucible by known technique (e.g., caustic
leaching), to leave the finished single crystal replacement body 99
(Step 612). After removal, the replacement body may be further
finished such as by machining, threading, surface treating, coating
or any other desirable finishing operation (Step 614).
[0093] Now referring to FIGS. 18 and 19, a method 700 according to
another disclosed non-limiting embodiment is provided that includes
additively manufacturing the replacement body 99 of a desired
superalloy (Step 702). Next, a core 102 is formed within the
replacement body 99, or a ceramic shell 104 is formed over the
replacement body 99, or both (Step 704). The ceramic core 102
and/or ceramic shell 104 may be formed over the additively
manufactured replacement body 99 by dipping or other process.
[0094] Then, as described above, to facilitate formation of the
single crystal microstructure (or columnar grain microstructure) in
the additively manufactured superalloy replacement body 99, the
body is re-melted within the shell of the crucible (Step 706), and
subjected to processes for creating the directionally solidified
microstructure within the replacement body 99. As indicated above,
the present disclosure is not limited to any particular technique
for creating the directionally solidified (e.g., single crystal
microstructure, columnar grain microstructure, etc.).
[0095] Following solidification, the solidified replacement body 99
may be removed from the crucible by known technique (e.g., caustic
leaching), to leave the finished single crystal replacement body 99
(Step 708). After removal, the replacement body may be further
finished such as by machining, threading, surface treating, coating
or any other desirable finishing operation. After removal, the
replacement body 99 may be further finished such as by machining,
threading, surface treating, coating or any other desirable
finishing operation (Step 710).
[0096] Now referring to FIG. 20, in the method 800 for the repair
or modification of a component of a gas turbine, a particular
section of the component of the gas turbine that is to be repaired
or modified (the aforesaid section is referred to herein as the
"target section" 93) is identified (Step 802), and this target
section is removed; e.g., cut out (Step 804). A data record may be
generated for a replacement body 99 that is to be produced. The
replacement body 99 is subsequently produced using the above
described additive manufacturing techniques (Step 806). Thereafter,
the replacement body 99 is integrated into the component that is to
be repaired or modified (Step 808). Accordingly, the method
includes removing the target section of the component (e.g.,
cutting it out), additively producing a corresponding replacement
body, and subsequently bonding the replacement body to the
component (Step 810). After the replacement body 99 is bonded to
the component, the component may be further finished such as by
machining, threading, surface treating, coating or any other
desirable finishing operation (Step 812).
[0097] The target section 93 of the component may be removed using
a variety of known techniques for material removal. The present
method is not limited to any particular technique. The term "target
section" as used herein, refers to a portion of the component that
includes characteristics (e.g., mechanical characteristics,
aerodynamic characteristics, etc.) that the user has identified for
replacement. Non-limiting examples of such characteristics include
cracks, regions compromised by erosion or oxidation, etc., but
could also include areas that have not specifically been subject to
damage, but rather may be an area that the user has identified for
modification (e.g., improved cooling or aerodynamic
characteristics, or mechanical strength characteristics, etc.). As
indicated above, the target section includes characteristics that
the user has identified for replacement, but also may extend beyond
the regions containing those characteristics. For example, in some
instances the target section may be sized to extend outside the
region containing the identified characteristics to provide a
buffer region to ensure all aspects of the characteristics are
addressed. In other instances, it may be beneficial to adopt a
uniform target section sizing for a given component; e.g., in
instances where a given component often experiences damage in a
particular region, a repair can be facilitated by adopting
uniformly sized target sections and corresponding uniformly sized
replacement bodies.
[0098] Once the target section is removed from the component, the
component may be analyzed using a measuring device (e.g., a
multi-dimensional mechanical or optical probe) to accurately
determine the geometry of the void left after the target section
was removed. This analysis may include an inspection of some, or
all, of the component to evaluate the component for deformation and
the like; e.g., aspects that may be unique to the particular
component as a result of its previous service life and/or original
manufacturing. Dimensional measurements made by measuring device
can subsequently be stored in a format such as a 3D CAD data file.
In the case of a uniquely sized target section, this 3D CAD data
file can be used in the generation of the replacement body. In the
case of a process that utilizes a uniformly sized target section,
the 3D CAD data file can be used to ensure the removal of the
uniform target section was correctly performed, dimensionally
speaking.
[0099] The 3D CAD data file representative of the void left by the
removal of the target section can be used alone or in combination
with a 3D CAD data file representing the replacement body to be
inserted into the void during the additive manufacturing of the
replacement body. The replacement body 3D CAD data file may
represent the component as originally manufactured, or may
represent the component in an enhanced configuration; e.g.,
improved cooling passage configurations, etc. The 3D CAD data file
can then be used to create an appropriate 3D CAD data file for
controlling the machinery used to additively manufacture the
replacement body; i.e., the replacement body itself, and the core
102 and shell 104 as applicable.
[0100] As indicated above, after the replacement body is additively
produced, but before the integration of the replacement body into
the component "W", it may be desirable to subject the replacement
body to various different manufacturing processes; e.g., processes
that clean the replacement body, improve the surface quality of the
replacement body, optimize the mechanical-technological properties
of the replacement body, etc.
[0101] Once the replacement body is in form for integration into
the component "W", the replacement body is then installed within
the void left by the removal of the target section and bonded to
the component "W". Bonding methods such as laser welding, Gas
tungsten arc welding (GTAW), Electron beam welding (EBW),
soldering, transition liquid phase bonding, combinations thereof,
etc., may be used, and the present disclosure is not limited to any
particular bonding process. After the replacement body is bonded in
place, it may be necessary to subject the component to further
manufacturing techniques (e.g., heat treatment, surface treatment,
coatings, etc.) to place the component "W" in finished form.
[0102] The method disclosed herein facilitates the relatively rapid
additive manufacture of single crystal microstructure replacement
bodies with complex internal passages and heretofore unavailable
surface finishes for accommodating the high temperature, high
stress operating environment of a gas turbine engine
environment.
[0103] It should be understood that relative positional terms such
as "forward," "aft," "upper," "lower," "above," "below," and the
like are with reference to the normal operational attitude of the
vehicle and should not be considered otherwise limiting.
[0104] It should be understood that like reference numerals
identify corresponding or similar elements throughout the several
drawings. It should also be understood that although a particular
component arrangement is disclosed in the illustrated embodiment,
other arrangements will benefit here from.
[0105] Although particular step sequences are shown, described, and
claimed, it should be understood that steps may be performed in any
order, separated or combined unless otherwise indicated and will
still benefit from the present disclosure.
[0106] The foregoing description is exemplary rather than defined
by the limitations within. Various non-limiting embodiments are
disclosed herein, however, one of ordinary skill in the art would
recognize that various modifications and variations in light of the
above teachings will fall within the scope of the appended claims.
It is therefore to be understood that within the scope of the
appended claims, the disclosure may be practiced other than as
specifically described. For that reason the appended claims should
be studied to determine true scope and content.
* * * * *