U.S. patent application number 11/315535 was filed with the patent office on 2007-06-21 for platinum modified nicocraly bondcoat for thermal barrier coating.
This patent application is currently assigned to United Technologies Corporation. Invention is credited to Asumini Kasule.
Application Number | 20070138019 11/315535 |
Document ID | / |
Family ID | 38016616 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070138019 |
Kind Code |
A1 |
Kasule; Asumini |
June 21, 2007 |
Platinum modified NiCoCrAlY bondcoat for thermal barrier
coating
Abstract
A turbine engine component has a substrate formed from a nickel
based superalloy and a platinum modified NiCoCrAlY bondcoat applied
to a surface of the substrate. Two methods for forming the platinum
modified NiCoCrAlY bondcoat are described herein.
Inventors: |
Kasule; Asumini; (New
Britain, CT) |
Correspondence
Address: |
BACHMAN & LAPOINTE, P.C. (P&W)
900 CHAPEL STREET, SUITE 1201
NEW HAVEN
CT
06510-2802
US
|
Assignee: |
United Technologies
Corporation
|
Family ID: |
38016616 |
Appl. No.: |
11/315535 |
Filed: |
December 21, 2005 |
Current U.S.
Class: |
205/191 |
Current CPC
Class: |
C23C 14/025 20130101;
C23C 14/16 20130101; C23C 28/3455 20130101; C23C 14/083 20130101;
C23C 14/5806 20130101; C23C 28/3215 20130101; C23C 28/325
20130101 |
Class at
Publication: |
205/191 |
International
Class: |
C23C 28/00 20060101
C23C028/00 |
Claims
1. A method for forming a coating on a substrate comprising the
steps of: providing a substrate; depositing a layer of platinum
onto a surface of said substrate; depositing a NiCoCrAlY layer onto
said platinum layer; and heat treating said substrate with said
deposited layers to form a platinum modified NiCoCrAlY
bondcoat.
2. The method according to claim 1, wherein said substrate
providing step comprises providing a substrate formed from a nickel
based alloy.
3. The method according to claim 1, wherein said platinum layer
depositing step comprises electroplating said platinum layer on
said substrate surface.
4. The method according to claim 1, wherein said platinum
depositing step comprises depositing a layer of platinum having a
thickness in the range of from about 0.01 to 1.0 mil.
5. The method according to claim 1, wherein said platinum in said
bondcoat is present in an amount from about 5.0 to 70 wt %.
6. The method according to claim 1, wherein said platinum in said
bondcoat is present in an amount from about 10 to 60 wt %.
7. The method according to claim 1, wherein said NiCoCrAlY
depositing step comprises depositing said NiCoCrAlY coating using a
cathodic arc deposition process.
8. The method according to claim 1, wherein said NiCoCrAlY
depositing step comprises depositing a NiCoCrAlY material
comprising from about 4.0 to 25 wt % chromium, from about 2.0 to 28
wt % cobalt, from about 5.5 to 15 wt % aluminum, from about 0.1 to
1.6 wt % yttrium, up to about 2.0 wt % hafnium, up to about 2.0 wt
% silicon, from about 3.0 to 12 wt % tantalum, from about 1.0 to 12
wt % tungsten, from about 1.0 to 10 wt % rhenium, up to about 2.0
wt % zirconium, up to about 4.0 wt % niobium, up to about 4.0 wt %
titanium, from about 0.2 to 6.0 wt % molybdenum, and the balance
nickel.
9. The method according to claim 1, wherein said NiCoCrAlY
depositing step comprises depositing a NiCoCrAlY material
comprising from about 4.0 to 18 wt % chromium, from about 2.0 to 24
wt % cobalt, from about 5.5 to 13.5 wt % aluminum, from about 0.1
to 0.8 wt % yttrium, from about 0.001 to 0.4 wt % hafnium, from
about 0.001 to 0.7 wt % silicon, from about 3.0 to 10 wt %
tantalum, from about 1.0 to 9.0 wt % tungsten, from about 1.0 to
5.0 wt % rhenium, from about 0.001 to 1.0 wt % zirconium, from
about 0.001 to 2.0 wt % niobium, from about 0.001 to 2.0 wt %
titanium, from about 0.2 to 4.0 wt % molybdenum, and the balance
nickel.
10. The method according to claim 1, wherein said heat treating
step comprises heating said substrate with said deposited layers at
a temperature in the range of from about 1200 to about 2100 degrees
Fahrenheit for a time period in the range of from about 2.0 to 15
hours to form said bondcoat.
11. The method according to claim 1, further comprising applying a
ceramic topcoat over said bondcoat having a thickness in the range
of from about 1.0 to 50 mils.
12. The method according to claim 11, wherein said ceramic topcoat
applying step comprises applying a yttria stabilized zirconia
topcoat.
13. The method according to claim 11, wherein said ceramic topcoat
applying step comprises applying a zirconia based pyrochlore
topcoat.
14. The method according to claim 11, wherein said ceramic topcoat
applying step comprises applying a 5 to 60 mol % gadolinia
stabilized zirconia topcoat.
15. The method according to claim 1, further comprising applying a
ceramic topcoat over said bondcoat having a thickness in the range
of from about 3.0 to 15 mils.
16. The method according to claim 11, wherein said ceramic topcoat
applying step comprises applying said topcoat using an EB-PVD
technique and thereby forming said topcoat with a columnar grained
microstructure wherein columnar grains are oriented substantially
perpendicular to said substrate surface and extend outwardly from
the bondcoat.
17. A method for forming a coating on a substrate comprising the
steps of: providing a substrate; depositing a NiCoCrAlY layer onto
a surface of said substrate; depositing a layer of platinum over
said NiCoCrAlY layer; and heat treating said substrate with said
deposited layers to form a platinum modified NiCoCrAlY
bondcoat.
18. The method according to claim 17, wherein said substrate
providing step comprises providing a substrate formed from a nickel
based alloy.
19. The method according to claim 17, wherein said platinum layer
depositing step comprises electroplating said platinum layer on
said substrate surface.
20. The method according to claim 17, wherein said platinum
depositing step comprises depositing a layer of platinum having a
thickness in the range of from 0.01 to 1.0 mil.
21. The method according to claim 17, wherein said heat treating
step comprises forming said bondcoat so that said platinum in said
bondcoat is present in an amount from about 5.0 to 70 wt %.
22. The method according to claim 17, wherein said heat treating
step comprises forming said bondcoat so that said platinum in said
bondcoat is present in an amount from about 10 to 60 wt %.
23. The method according to claim 17, wherein said NiCoCrAlY
depositing step comprises depositing said NiCoCrAlY coating using
an cathodic arc deposition process.
24. The method according to claim 17, wherein said NiCoCrAlY
depositing step comprises depositing a NiCoCrAlY material
comprising from about 4.0 to 25 wt % chromium, from about 2.0 to 28
wt % cobalt, from about 5.5 to 15 wt % aluminum, from about 0.1 to
1.6 wt % yttrium, up to about 2.0 wt % hafnium, up to about 2.0 wt
% silicon, from about 3.0 to 12 wt % tantalum, from about 1.0 to 12
wt % tungsten, from about 1.0 to 10 wt % rhenium, up to about 2.0
wt % zirconium, up to about 4.0 wt % niobium, up to about 4.0 wt %
titanium, from about 0.2 to 6.0 wt % molybdenum, and the balance
nickel.
25. The method according to claim 17, wherein said NiCoCrAlY
depositing step comprises depositing a NiCoCrAlY material
comprising from about 4.0 to 18 wt % chromium, from about 2.0 to 24
wt % cobalt, from about 5.5 to 13.5 wt % aluminum, from about 0.1
to 0.8 wt % yttrium, from about 0.001 to 0.4 wt % hafnium, from
about 0.001 to 0.7 wt % silicon, from about 3.0 to 10 wt %
tantalum, from about 1.0 to 9.0 wt % tungsten, from about 1.0 to
5.0 wt % rhenium, from about 0.001 to 1.0 wt % zirconium, from
about 0.001 to 2.0 wt % niobium, from about 0.001 to 2.0 wt %
titanium, from about 0.2 to 4.0 wt % molybdenum, and the balance
nickel.
26. The method according to claim 17, wherein said heat treating
step comprises heating said substrate with said deposited layers at
a temperature in the range of from about 1200 to about 2100 degrees
Fahrenheit for a time period in the range of from about 2.0 to 15
hours to form said bondcoat.
27. The method according to claim 17, further comprising applying a
ceramic topcoat over said bondcoat having a thickness in the range
of from about 1.0 to 50 mils.
28. The method according to claim 17, further comprising applying a
ceramic topcoat over said bondcoat having a thickness in the range
of from about 3.0 to 15 mils.
29. The method according to claim 27, wherein said ceramic topcoat
applying step comprises applying a yttria stabilized zirconia
topcoat.
30. The method according to claim 27, wherein said ceramic topcoat
applying step comprises applying a zirconia based pyrochlore
topcoat.
31. The method according to claim 27, wherein said ceramic topcoat
applying step comprises applying a 5.0 to 60 mol % gadolinia
stabilized zirconia.
32. The method according to claim 27, wherein said ceramic topcoat
applying step comprises applying said topcoat using an EB-PVD
technique and thereby forming said topcoat with a columnar grained
microstructure wherein columnar grains are oriented substantially
perpendicular to said substrate surface and extend outwardly from
the bondcoat.
33. A turbine engine component comprising: a substrate formed from
a nickel based superalloy; and a platinum modified NiCoCrAlY
bondcoat applied to a surface of said substrate.
34. A turbine engine component according to claim 33, wherein said
bondcoat has a thickness in the range of from 1.0 to 5.0 mils.
35. A turbine engine component according to claim 33, further
comprising a ceramic topcoat and a layer of aluminum oxide scale
between said ceramic topcoat and said bondcoat, whereby said
bondcoat improves adherence of said aluminum oxide scale.
36. A turbine engine component according to claim 35, wherein said
ceramic topcoat comprises a yttria stabilized zirconia.
37. A turbine engine component according to claim 35, wherein said
ceramic topcoat comprises a zirconia based pyrochlore topcoat.
38. A turbine engine component according to claim 35, wherein said
ceramic topcoat comprises a 5 to 60 mol % gadolinia stabilized
zirconia.
39. A turbine engine component according to claim 35, wherein said
ceramic topcoat has a thickness in the range of from 1.0 to 50 mils
and a columnar grained microstructure with columnar grains oriented
substantially perpendicular to the surface of the substrate and
extending outwardly from the bondcoat and alumina scale.
40. The turbine engine component according to claim 39, wherein
said thickness in the range of from 3.0 to 15 mils.
41. The turbine engine component according to claim 33, wherein
said bondcoat has a three-dimensional interconnected two-phase
microstructure with grain sizes from 0.5 to 30 microns.
42. The turbine engine component according to claim 33, wherein
said bondcoat contains from about 5.0 to 70 wt % platinum.
43. The turbine engine component according to claim 33, wherein
said bondcoat contains from about 10 to 60 wt % platinum.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a platinum modified
NiCoCrAlY bondcoat for a thermal barrier coating and a method for
forming same.
[0003] (2) Prior Art
[0004] Turbine engine components are subjected to elevated
temperatures as a result of their exposure to high temperature gas.
Such exposure can lead to the creation of unwanted defects in the
components. To protect the components, bondcoats and/or ceramic
topcoats are applied to the surfaces of the turbine engine
components.
[0005] Despite the existence of such coatings, there is still a
need for coatings which provide the components with improved
oxidation resistance.
SUMMARY OF THE INVENTION
[0006] Accordingly, the present invention is directed to an
improved coating system for a turbine engine component and methods
for forming same.
[0007] In accordance with the present invention, there is provided
a method for forming a coating on a substrate. The method broadly
comprises the steps of providing a substrate, depositing a layer of
platinum onto a surface of the substrate, depositing a NiCoCrAlY
layer onto the platinum layer, and heat treating the substrate with
the deposited layers to form a platinum modified NiCoCrAlY
bondcoat.
[0008] In accordance with the present invention, there is provided
an alternative method for forming a coating on a substrate. The
method broadly comprises the steps of providing a substrate,
depositing a NiCoCrAlY layer onto a surface of the substrate,
depositing a layer of platinum over the NiCoCrAlY layer, and heat
treating the substrate with the deposited layers to form a platinum
modified NiCoCrAlY bondcoat.
[0009] In accordance with the present invention, there is provided
a turbine engine component broadly comprising a substrate formed
from a nickel based superalloy and a platinum modified NiCoCrAlY
bondcoat applied to a surface of the substrate.
[0010] Other details of the platinum modified NiCoCrAlY bondcoat
for a thermal barrier coating of the present invention, as well as
other objects and advantages attendant thereto, are set forth in
the following description and the accompanying drawings wherein
like reference numerals depict like elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic representation of a first coating
system in accordance with the present invention; and
[0012] FIG. 2 is a schematic representation of a second coating
system in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0013] As discussed, the present invention is directed to an
improved coating system that can be applied to turbine engine
components, such as vanes, blades, and seals, that are exposed to
high temperature gases. The coating system includes a thin bondcoat
that offers oxidation protection to the nickel based superalloy
forming the turbine engine component. The bondcoat is a platinum
modified NiCoCrAlY coating. The addition of the platinum to the
bondcoat improves the adherence of the aluminum oxide scale that
forms during use of the turbine engine component.
[0014] FIG. 1 illustrates a first sequence for forming a coating
system in accordance with the present invention. As shown therein,
a nickel based alloy substrate 10 has a surface 12. A layer 14 of
platinum is deposited onto the surface 12, preferably using an
electroplating technique. For purposes of illustration only, a
useful electroplating bath may contain platinum quantities in the
range of 17 to 26 grams/liter. The current density may range from
20 to 30 amps per square foot. The time for electroplating will be
determined by the required thickness. The electroplating bath
temperature can go up to 200 degrees F. The layer of electroplated
platinum may have a thickness in the range of from about 0.01 to
1.0 mil. These electroplating parameters are offered merely for
purposes of illustration as other platinum electroplating
parameters can be employed. The platinum layer also can be
deposited by techniques other than electroplating, such as
including, but not limited to sputtering, and other deposition
techniques.
[0015] Thereafter, a layer 16 of NiCoCrAlY material is deposited
onto the platinum layer. Preferably, the NiCoCrAlY material is
deposited using a cathodic arc deposition process. Techniques for
applying the coatings of the present invention by cathodic arc
plasma vapor deposition are discussed in U.S. Pat. Nos. 5,972,185;
5,932,078; 6,036,828; 5,792,267; and 6,224,726, all of which are
incorporated by reference herein. Alternate methods of deposition
including, but not limited to, other plasma vapor deposition
techniques such as magnetron sputtering and electron beam plasma
vapor deposition may be used. When thickness concerns are not
present, various thermal spray techniques such as low pressure
plasma spray and HVOF (high velocity oxy-fuel) techniques may be
utilized. The NiCoCrAlY material which is deposited may have a
composition comprising from about 4.0 to 25 wt %, preferably from
about 4.0 to 18 wt %, chromium, from about 2.0 to 28 wt %,
preferably from about 2.0 to 24 wt %, cobalt, from about 5.5 to 15
wt %, preferably from about 5.5 to 13.5 wt %, aluminum, from about
0.1 to 1.6 wt %, preferably from about 0.1 to 0.8 wt %, yttrium, up
to about 2.0 wt %, preferably from about 0.001 to 0.4 wt %,
hafnium, up to about 2.0 wt %, preferably from about 0.001 to 0.7
wt %, silicon, from about 3.0 to 12 wt %, preferably from about 3.0
to 10 wt %, tantalum, from about 1.0 to 12 wt %, preferably from
about 1.0 to 9.0 wt % tungsten, from 1.0 to 10 wt %, preferably
from about 1.0 to 5.0 wt % rhenium, up to 2.0 wt %, preferably from
0.001 to 1.0 wt %, zirconium, up to 4.0 wt %, preferably from about
0.001 to 2.0 wt %, niobium, up to about 4.0 wt %, preferably from
about 0.001 to 2.0 wt %, titanium, from about 0.2 to 6.0 wt %,
preferably from about 0.2 to 4.0 wt %, molybdenum, and the balance
nickel. The coating may also comprise up to 2.0 wt % of other
elements as impurities. The yttrium in the coating improves the
adherence of the aluminum oxide scale layer 18 which is formed
during use. Sulfur would usually migrate to the aluminum oxide
scale layer 18; however, the presence of yttrium prevents this from
occurring.
[0016] Following deposition of the NiCoCrAlY material, the
substrate 10 with the deposited layers 14 and 16 is subjected to a
diffusion heat treatment. The diffusion heat treatment is carried
out at a temperature in the range of from about 1200 to about 2100
degrees Fahrenheit for a time period in the range of from about 2.0
to 15 hours. The diffusion treatment is preferably carried out in
an inert gas atmosphere such as an argon atmosphere. The fully heat
treated platinum modified NiCoCrAlY bondcoat may have a platinum
content in the range of from 5.0 to 0.70 wt %, preferably from 10
to 60 wt %, and a thickness in the range of from about 1.0 to 5.0
mils. The bondcoat typically forms a dense three-dimensional
interconnected two-phase microstructure with grains sizes ranging
from 0.5 to 30 microns. Platinum may be substituted by palladium,
rhodium, iridium, and mixtures thereof.
[0017] Once the bondcoat is formed, a ceramic topcoat 20 may be
applied using any suitable ceramic composition known in the art. A
preferred composition for the ceramic topcoat 20 is yttria
stabilized zirconia such as 7.0 wt % yttria stabilized zirconia.
Other favored compositions include zirconia based pyrochlores, 5.0
to 60 mol % gadolinia stabilized zirconia, and zirconia stabilized
with various lanthanide sesquioxides and mixtures thereof described
in U.S. Pat. No. 6,730,422, which is incorporated by reference
herein. The ceramic topcoat layer 20 may have a thickness in the
range of from about 1.0 to 50 mils, preferably from about 3.0 to 15
mils.
[0018] The ceramic topcoat 20 may be applied using any suitable
electron beam-physical vapor deposition (EB-PVD) technique known in
the art. A preferred deposition technique is electron beam physical
vapor deposition (EB-PVD). Ceramic coatings are preferably applied
to bondcoated substrates at substrate temperature ranging from
about 1700 to 2200 degrees Fahrenheit, and chamber pressures from
about 0.1 to 1.0 millitorr. Deposition time ranges from 20 to 120
minutes using feedstock federates of from about 0.2 to 1.5 inches
per hour. Other suitable deposition techniques include thermal
spraying, chemical vapor deposition, and other physical vapor
deposition techniques including, but not limited to, cathodic arc
deposition, sputtering, and thermal evaporation. Either an inert or
reactive atmosphere can optionally be used in all of these
deposition techniques, as known to be appropriate to one skilled in
the art.
[0019] When produced by vapor deposition techniques, the ceramic
topcoat layer 20 is characterized by a columnar grained
microstructure with the columnar grains or columns being oriented
substantially perpendicular to the surface 12. The columnar grains
or columns extend outwardly from the bondcoat or from an aluminum
oxide scale layer, 18 that is intentionally formed on the bondcoat
before or during deposition of the ceramic layer 20. In addition,
vapor deposition techniques that utilize means to increase the
mobility of vapor species on the substrate surface, such as
substrate bias or high-energy ion impingement, result in dense
equiaxed ceramic coatings. Alternatively, thermally sprayed
coatings that form by depositing liquid droplets on the substrate
have a porous microstructure consisting of randomly piled frozen
splats of liquid. These splats are typically microcracked and
typically trap pores between them, resulting in a strain-tolerant
microstructure.
[0020] Referring now to FIG. 2, there is shown an alternative
sequence for forming a coating system in accordance with the
present invention. In this method, the bondcoat is formed by
depositing the NiCoCrAlY layer 16 onto the surface 12 of the
substrate and then depositing the platinum layer 14 over the
NiCoCrAlY layer 16. The NiCoCrAlY layer may have the same
composition as described above and may be deposited using the
technique described above. The platinum layer 14 may have the same
compositional range as described above and may be deposited using
the electroplating technique described above. The diffusion heat
treatment step is performed after the platinum depositing step
using the same parameters as described above. The preferred
bondcoat thickness is the same as that discussed in the prior
method. The ceramic topcoat layer 20 may be deposited as discussed
above.
[0021] Specimens coated in accordance with the present invention
have survived greater than 1000 hours of cyclic oxidation in a
burner rig at temperatures in excess of 2000 degrees
Fahrenheit.
[0022] It is apparent that there has been provided in accordance
with the present invention a platinum modified NiCoCrAlY bondcoat
for a thermal barrier coating which fully satisfies the objects,
means and advantages set forth hereinbefore. While the present
invention has been described in the context of specific embodiments
thereof, other unforeseeable alternatives, modifications, and
variations will become apparent to those skilled in the art having
read the foregoing description. Accordingly, it is intended to
embrace those alternatives, modifications, and variations as fall
within the broad scope of the appended claims.
* * * * *