U.S. patent application number 15/487533 was filed with the patent office on 2017-11-02 for multilayer thermal barrier coating material.
The applicant listed for this patent is General Electric Company. Invention is credited to Michael David Clark, Douglas Gerard Konitzer.
Application Number | 20170314139 15/487533 |
Document ID | / |
Family ID | 58701367 |
Filed Date | 2017-11-02 |
United States Patent
Application |
20170314139 |
Kind Code |
A1 |
Clark; Michael David ; et
al. |
November 2, 2017 |
MULTILAYER THERMAL BARRIER COATING MATERIAL
Abstract
A thermal barrier coating system is disclosed.
Inventors: |
Clark; Michael David;
(Liberty Township, OH) ; Konitzer; Douglas Gerard;
(West Chester, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
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|
Family ID: |
58701367 |
Appl. No.: |
15/487533 |
Filed: |
April 14, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15140822 |
Apr 28, 2016 |
9657387 |
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15487533 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 28/345 20130101;
C23C 14/025 20130101; C23C 14/30 20130101; C23C 28/00 20130101;
C23C 14/06 20130101; C23C 28/3215 20130101; C23C 28/321 20130101;
C23C 28/3455 20130101; C23C 14/221 20130101; C23C 14/28
20130101 |
International
Class: |
C23C 28/00 20060101
C23C028/00 |
Claims
1. A thermal barrier coating system on a surface of a substrate,
comprising: a bond coating on the surface of the substrate; a first
layer on the bond coating, wherein the first layer comprises a
first ceramic material; a blended layer on the first layer, wherein
the blended layer comprises the first ceramic material and a second
ceramic material, wherein the second ceramic material is different
from the first ceramic material; and a second layer on the blended
layer, wherein the second layer comprises the second ceramic
material, and wherein the blended layer includes a granular
interface between the first layer and the second layer.
2. The system of claim 1, wherein the blended layer forms a
granular interface between the first layer and the second
layer.
3. The system of claim 1, wherein the blended layer has a graded
composition extending from the first layer to the second layer.
4. The system of claim 1, wherein the first layer and the second
layer forms a thermal barrier coating having columnar grains, and
wherein the blended layer of the thermal barrier coating is a
mixture of the first and second ceramic compositions.
5. The system of claim 1, wherein the blended layer has a higher
concentration of the first ceramic source material than the second
ceramic source material at its interface with the first layer and a
higher concentration of the second ceramic source material than the
first ceramic source material at its interface with the second
layer.
6. The system of claim 1, wherein the blended layer has a stepped
composition extending from the first layer to the second layer.
7. The system of claim 1, wherein the blended layer is formed from
at least two layers.
8. The system of claim 1, wherein the blended layer is formed from
a plurality of sub-layers, and wherein each of the sublayers have a
composition that increases in concentration of the second ceramic
source material as it extends away from the first layer.
9. The system of claim 1, further comprising a second blended layer
between the first layer and the second layer, wherein the second
blended layer has a greater concentration of the second ceramic
source material than the first blended layer.
10. The system of claim 1, wherein the first ceramic source
material comprises yttria-stabilized zirconia.
11. The system of claim 1, wherein the second ceramic source
material is configured to increase the resistance of the thermal
barrier coating to infiltration by molten CMAS.
12. The system of claim 1, wherein the second ceramic source
material provides improved impact resistance to the component.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This Application is a divisional of U.S. patent application
Ser. No. 15/140,822, entitled "SYSTEM AND METHODS OF FORMING A
MULTILAYER THERMAL BARRIER COATING SYSTEM," filed 28 Apr. 2016,
which is herein incorporated by reference.
FIELD OF THE INFORMATION
[0002] This invention generally relates to systems and for coatings
on components exposed to high temperatures, such as the hostile
thermal environment of a gas turbine engine. More particularly,
this invention is directed to a multi-layered thermal barrier
coating.
BACKGROUND OF THE INVENTION
[0003] Hot section components of gas turbine engines are often
protected by a thermal barrier coating (TBC), which reduces the
temperature of the underlying component substrate and thereby
prolongs the service life of the component. Ceramic materials and
particularly yttria-stabilized zirconia (YSZ) are widely used as
TBC materials because of their high temperature capability, low
thermal conductivity, and relative ease of deposition by plasma
spraying, flame spraying and physical vapor deposition (PVD)
techniques. Air plasma spraying (APS) has the advantages of
relatively low equipment costs and ease of application and masking,
while TBC's employed in the highest temperature regions of gas
turbine engines are often deposited by PVD, particularly
electron-beam PVD (EBPVD), which yields a strain-tolerant columnar
grain structure. Similar columnar microstructures can be produced
using other atomic and molecular vapor processes.
[0004] Observed failure mechanisms in turbine multi-layer systems
are often anchored around interfacial challenges between the
surface of the component and the TBC and/or different layers of the
TBC. Such issues, including surface contamination, process
inhomogeneity during start-up (e.g. inter-layer porosity, unmelts,
etc.), and source cross-contamination can lead to interfaces with
unreliable functionality, thereby endangering the multi-layer
system's stability.
[0005] Thus, a need exists for multi-layered coating systems where
individual layers can provide improvements to the coating system's
damage tolerance, thermal properties, reactivity, etc.
BRIEF DESCRIPTION OF THE INVENTION
[0006] Aspects and advantages of the invention will be set forth in
part in the following description, or may be obvious from the
description, or may be learned through practice of the
invention.
[0007] Methods are generally provided for forming a thermal barrier
coating system on a surface of a component. The thermal barrier
coating system generally includes a thermal barrier coating that
has columnar grains. In one embodiment, the method includes
introducing the component into a coating chamber, where a first
ceramic source material and a second ceramic source material are
positioned within the coating chamber of a physical vapor
deposition apparatus. An energy source is directed onto the first
ceramic source material to vaporize the first ceramic source
material to deposit a first layer on the component. The energy
source is alternated between the first ceramic source material and
the second ceramic source material to form a blended layer on the
first layer, with the blended layer being formed from vapors from
the first ceramic source material and the second ceramic source
material.
[0008] In certain embodiments, after alternating the energy source
between the first ceramic source material and the second ceramic
source material, the energy source is directed onto the second
ceramic source material to vaporize the second ceramic source
material to deposit a second layer on the blended layer such that
the blended layer is positioned between the first layer and the
second layer.
[0009] A thermal barrier coating system is also generally provided,
which can be formed on a surface of a substrate according to such
methods described above. In one embodiment, the thermal barrier
coating system includes a bond coating on the surface of the
substrate; a first layer on the bond coating and formed from a
first ceramic material; a blended layer on the first layer and
formed from the first ceramic material and a second ceramic
material that is different from the first ceramic material; and a
second layer on the blended layer and formed from the second
ceramic material. Generally, the blended layer includes a granular
interface between the first layer and the second layer.
[0010] These and other features, aspects and advantages of the
present invention will become better understood with reference to
the following description and appended claims. The accompanying
drawings, which are incorporated in and constitute a part of this
specification, illustrate embodiments of the invention and,
together with the description, serve to explain the principles of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A full and enabling disclosure of the present invention,
including the best mode thereof, directed to one of ordinary skill
in the art, is set forth in the specification, which makes
reference to the appended Figs., in which:
[0012] FIG. 1 shows a general schematic of a cross-sectional view
of an exemplary electron beam physical vapor deposition apparatus
for use in depositing a first layer of a thermal barrier coating
system;
[0013] FIG. 2 shows a general schematic of a cross-sectional view
of an exemplary electron beam physical vapor deposition apparatus
for use in depositing a an intermediate layer of a thermal barrier
coating system;
[0014] FIG. 3 shows a general schematic of a cross-sectional view
of an exemplary electron beam physical vapor deposition apparatus
for use in depositing a second layer of a thermal barrier coating
system;
[0015] FIG. 4 shows a perspective view of an exemplary high
pressure turbine blade;
[0016] FIG. 5 shows an exemplary cross-sectional view of the blade
of FIG. 4, which shows an exemplary thermal barrier coating system
in accordance with one embodiment of the present disclosure;
[0017] FIG. 6 shows a cross-sectional view of an exemplary granular
interface between the first layer and the second layer;
[0018] FIG. 7 shows a cross-sectional view of another exemplary
granular interface between the first layer and the second layer;
and
[0019] FIG. 8 shows a diagram of an exemplary method of making a
thermal barrier coating system.
[0020] Repeat use of reference characters in the present
specification and drawings is intended to represent the same or
analogous features or elements of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Reference now will be made in detail to embodiments of the
invention, one or more examples of which are illustrated in the
drawings. Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that various modifications and
variations can be made in the present invention without departing
from the scope or spirit of the invention. For instance, features
illustrated or described as part of one embodiment can be used with
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0022] As used herein, the terms "first", "second", and "third" may
be used interchangeably to distinguish one component from another
and are not intended to signify location or importance of the
individual components.
[0023] The terms "upstream" and "downstream" refer to the relative
direction with respect to fluid flow in a fluid pathway. For
example, "upstream" refers to the direction from which the fluid
flows, and "downstream" refers to the direction to which the fluid
flows.
[0024] In the present disclosure, when a layer is being described
as "on" or "over" another layer or substrate, it is to be
understood that the layers can either be directly contacting each
other or have another layer or feature between the layers. Thus,
these terms are simply describing the relative position of the
layers to each other and do not necessarily mean "on top of" since
the relative position above or below depends upon the orientation
of the device to the viewer.
[0025] Systems and methods are generally provided for a single-step
deposition utilizing multi-sources such that individual layers of
unique chemistries can be deposited from different sources without
interrupting the deposition process. These systems and methods
allow the layer ordering and interfacial transitions to be tailed
as desired, while mitigating prevalent interfacial issues such as
contamination and process in-homogeneity (e.g. inter-layer
porosity, unmelts, etc.). Thus, robust interfaces can be
constructed maximizing the benefits of the coating system.
Additionally, it is possible to include as many layers of varying
composition with any periodicity that is desired. For example, a
two pool system is shown and described with respect to FIGS. 1-3
for varying two compositions; however, with advanced machines
additional pools may be included as desired to form layered TBC's
with any system of layers and compositions. For example, 2 sources
to about 5 sources can be included in the deposition chamber. The
layered compositions provide a commercial advantage in that they
allow the desire of more durable TBC's which provides improved
cooling for turbine components.
[0026] Embodiments of the thermal barrier coating system described
here are described in reference to a high pressure turbine blade 10
shown in FIG. 4. However, the present disclosure is generally
applicable to any component that operates within a thermally and
chemically hostile environment. The blade 10 generally includes an
airfoil 12 against which hot combustion gases are directed during
operation of the gas turbine engine, and whose surfaces are
therefore subjected to severe attack by oxidation, hot corrosion
and erosion. The airfoil 12 is anchored to a turbine disk (not
shown) with a dovetail 14 formed on a root section 16 of the blade
10. Cooling holes 18 are present in the airfoil 12 through which
bleed air is forced to transfer heat from the blade 10.
[0027] The surface of the airfoil 12 is protected by a TBC system
20, represented in FIG. 5 as including a metallic bond coat 24 that
overlies the surface 23 of a substrate 22, which may be a
superalloy and typically the base material of the blade 10. The
bond coat 24 is, in particular embodiments, an aluminum-rich
composition, such as an overlay coating of a MCrAlX alloy or a
diffusion coating such as a diffusion aluminide or a diffusion
platinum aluminide. Alternatively, overlay coatings of beta-phase
nickel aluminide ((.beta.NiAl) intermetallic can be used as the
bond coat 24. Such aluminum-rich bond coats develop an aluminum
oxide (alumina) scale 28, which is grown by oxidation of the bond
coat 24. The alumina scale 28 chemically bonds a thermal-insulating
TBC 26 to the bond coat 24 and substrate 22. The TBC 26 of this
invention is intended to be deposited to a thickness that is
sufficient to provide the required thermal protection for the
underlying substrate 22 and blade 10. A suitable thickness is
generally on the order of about 75 to about 300 micrometers.
[0028] However, TBC materials are susceptible to attack by CMAS. As
discussed previously, CMAS is a relatively low melting eutectic
that when molten is able to infiltrate columnar and porous TBC
materials, and subsequently resolidify to promote spallation during
thermal cycling. To reduce its vulnerability to spallation from
contamination by CMAS and other potential contaminants, the TBC 26
is formed of a base ceramic material co-deposited with at least one
additional ceramic material capable of interacting with CMAS. The
TBC 26 shown in FIG. 5 is shown as comprising two zones--an inner
layer 30 (e.g., a first layer) closer to the bond coat 24 and an
outer portion 32 (e.g., a second layer) overlying the inner layer
30. As will be discussed in greater detail below, the inner layer
30 and the outer layer 32 of the TBC 26 are not discrete layers,
but instead may differ in their compositions.
[0029] The compositions of the inner layer 30 and the outer layer
32 can be independently selected from ceramic compositions such
that the inner layer 30 is formed from a first ceramic material and
the outer layer 32 is formed from a second ceramic material. In one
embodiment, the inner layer 30 and the outer layer 32 are formed of
the same base ceramic material, with at least the outer layer 32
containing the additional ceramic material(s). For example, the
outer layer 32 may include a ceramic material that can render the
TBC 26 more resistant to infiltration by CMAS and other potential
high-temperature contaminants. In terms of processing, high
temperature capability and low thermal conductivity, a preferred
base ceramic material for the TBC 26 is an yttria-stabilized
zirconia (YSZ), such as a composition of about 3 to about 8 weight
percent yttria, though other ceramic materials could be used, such
as nonstabilized zirconia, or zirconia partially or fully
stabilized by magnesia, ceria, scandia or other oxides. In one
embodiment, the additional ceramic material(s) present in at least
the outer layer 32 of the TBC 26 is capable of interacting with
molten CMAS to form a compound with a melting temperature that is
significantly higher than CMAS, so that the reaction product of
CMAS and the ceramic material does not melt and does not infiltrate
the TBC 26. Additionally, "sacrificial layer" materials are
potential candidates for the additional ceramic material of these
layers 30, 32. In other embodiments, the second ceramic source
material of the outer layer 32 provides improved impact resistance
to the underlying layers and component.
[0030] As shown in FIG. 5, a blended layer 31 is positioned between
the inner layer 30 and the outer layer 32 of the TBC 26. The
blended layer 31 includes, in one embodiment, a combination of the
compositions of inner layers 30 and outer layers 32. For example,
the blended layer 31 can be a mixture of the first and second
ceramic compositions. For example, the blended layer 31 can have a
graded composition extending from the inner layer 30 to the outer
layer 32.
[0031] In other embodiments, the blended layer 31 can have a
stepped composition formed from a plurality of sub-layers (e.g., at
least two sub-layers, such as about 2 to about 10 sub-layers), with
each of the sub-layers having a composition that increases in
concentration of the second ceramic source material as it extends
away from the first layer. For example, FIG. 6 shows a blended
layer 31 formed from a first blended layer 42 and a second blended
layer 44. For example, after directing the energy source 68 onto
the first ceramic source material 54 as shown in FIG. 1, the energy
source 68 is alternated between the first ceramic source material
54 and the second ceramic source material 56 at a first alternating
rate to form a first blended layer 42. Thereafter, the energy
source 68 is alternated between the first ceramic source material
54 and the second ceramic source material 56 at a second
alternating rate to form a second blended layer 44 such that the
second blended layer 44 has a greater concentration of the second
ceramic source material 56 than the first blended layer 42.
[0032] Referring to FIG. 7, the inner layer 30 and the outer layer
32 of the TBC 26 is shown having a strain-tolerant microstructure
of columnar grains 27. Additionally, the blended layer 31 includes
columnar grains 33 that extend between the columnar grains 27 of
the inner layer 30 and the outer layer 32. As such, the blended
layer 31 can strengthen the interaction between the inner layer 30
and the outer layer 32.
[0033] Such columnar microstructures can be achieved by depositing
the TBC 26 using a physical vapor deposition (PVD) technique, such
as EBPVD, though other PVD techniques could be used such as laser
beam PVD, sputtering (e.g., magnetron), ion plasma, and cathodic
arc deposition. EBPVD processes generally require the presence of
an evaporation source of the desired coating composition, and an
electron beam at an appropriate power level to create a vapor of
the evaporation source in the presence of the surface to be coated.
In order to form the blended layer 31 between the inner layer 30
and the outer layer 32, multiple evaporation sources are used to
deposit the TBC 26.
[0034] FIGS. 1-3 schematically represents an EBPVD coating
apparatus 50, including a coating chamber 52 in which a component
76 is suspended for forming the TBC 26. FIG. 3 shows the TBC 26
including the inner layer 30, the blended layer 31, and the outer
layer 32 formed sequentially in the coating apparatus 50 according
to FIGS. 1-3. The coating apparatus 50 forms the multilayer TBC 26
through deposition on the component 76 by melting and vaporizing a
first ceramic source material 54 (e.g., first ingot 54) and a
second ceramic source material 56 (e.g., second ingot 56) of the
desired ceramic materials with an energy source 68 with directed
energy 66 (e.g., an electron beam gun 68 with an electron beam 66
or a laser source 68 produced by laser source 68).
[0035] The energy source 68 is moveable so as to direct energy 66
selectively between the first ceramic source material 54 and a
second ceramic source material 56. In depositing the TBC 26 to have
an inner layer 30, a blended layer 31, and an outer layer 32 with
different compositions, the inner layer 30 is first deposited by
evaporating only the first source 54 as shown in FIG. 1 of the
first ceramic material 54 (e.g., YSZ). FIG. 1 shows the energy
source 68 directing energy 66 at the first ceramic source material
54 to produce a first vapor 70 so as to form the first layer 30 on
the component 76. The intensity of the beam 66 is sufficient to
produce vapor cloud 70 within the coating chamber 52, and then
contact and condense on the component 76 to form the inner layer
30. As shown, the vapor cloud 70 evaporates from pool 62 of the
molten coating materials contained within reservoirs formed by
crucibles 58 that surround the upper end of the first source 54. In
particular embodiments, a suitable thickness for the inner portion
30 of the TBC 26 is on the order of about 50 to about 500
micrometers, more preferably about 75 to about 100 micrometers.
[0036] Once a desired thickness for the inner layer 30 is deposited
on the component 76, the energy source 68 is alternated between the
first source 54 and the second source 56 such that evaporation
commences of the second source 56 as shown FIG. 2. That is, FIG. 2
shows the energy source 68 directed energy 66 alternating between
the first ceramic source material 54 and the second ceramic source
material 56 to produce a mixture of the first vapor 70 and the
second vapor 72 so as to form the blended layer 31 on the first
layer 30. Generally, the energy source 68 directed energy 66
alternating between the first ceramic source material 54 and the
second ceramic source material 56 at a frequency and a power level
(e.g., intensity) sufficient to produce vapor clouds 70 and 72 that
mix within the coating chamber 52, which then contact and condense
on the component 76 to form the blended layer 31. As shown, the
vapor clouds 70 and 72 evaporate from separate pools 62 and 64,
respectively, of the molten coating materials contained within
reservoirs formed by crucibles 58 that surround the upper ends of
the sources 54 and 56, respectively.
[0037] The blended layer 31 is formed to include the desired
composition (e.g., a mixture of the first ceramic material 54 and
the second ceramic material 56). In one embodiment, the energy
source 68 alternates in a controlled manner so as to direct the
relative amount of vapor 70, 72 within the chamber 52 so as to form
a controlled composition within the blended layer 31. For example,
the blended layer 31 can have a graded composition extending from
the inner layer 30 to the outer layer 32 such that the composition
of the blended layer 31 has a higher concentration of the first
ceramic source material than the second ceramic source material at
its interface with the first layer and a higher concentration of
the second ceramic source material than the first ceramic source
material at its interface with the second layer. Such a graded
composition can gradually change though its thickness extending
from the first layer to the second layer. Such a graded layer can
be formed by focusing on the first ceramic source material 54
longer than the second ceramic source material 56 when beginning to
deposit the blended layer, and then changing the time of focus on
each of the first ceramic source material 54 and the second ceramic
source material 56 as the blended layer is depositing (i.e.,
shortening the focus time on the first ceramic source material 54
and lengthening the second ceramic source material 56).
Alternatively, the blended layer 31 can be deposited to have a
uniform composition throughout its thickness from the inner layer
30 and the outer layer 32 by evaporating both sources 54, 56
simultaneously.
[0038] Finally, FIG. 3 shows the energy source 68 directing energy
66 at the second ceramic source material 56 to produce a second
vapor 72 so as to form the second layer 32 on the blended layer 31.
The intensity of the beam 66 is sufficient to produce vapor cloud
72 within the coating chamber 52, and then contact and condense on
the component 76 to form the outer layer 32 on the blended layer
31. As shown, the vapor cloud 72 evaporates from pool 64 of the
molten coating materials contained within reservoirs formed by
crucibles 58 that surround the upper end of the second source 56. A
suitable thickness for the outer layer 32 of the TBC 26 is about 10
to about 50 micrometers, more preferably about 10 to about 25
micrometers.
[0039] As the source materials are gradually consumed by the
deposition process, the first and second source materials 54, 56
are incrementally fed into the chamber 52.
[0040] FIG. 8 shows a diagram of an exemplary method 100 of forming
a thermal barrier coating system on a surface of a component, with
the thermal barrier coating system comprising a thermal barrier
coating that has columnar grains. At 102, a component is introduced
into a coating chamber. For example, a first ceramic source
material and a second ceramic source material can be positioned
within the coating chamber (e.g., of a physical vapor deposition
apparatus). At 104, an energy source is onto the first ceramic
source material to vaporize the first ceramic source material to
deposit a first layer on the component. At 106, the energy source
is alternated between the first ceramic source material and the
second ceramic source material to form a blended layer on the first
layer. At 108, the energy source is directed onto the second
ceramic source material to vaporize the second ceramic source
material to deposit a second layer on the blended layer.
[0041] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they include structural elements that do not
differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *