U.S. patent application number 12/610393 was filed with the patent office on 2010-02-25 for thermal barrier coating compositions, processes for applying same and articles coated with same.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to Melvin Freling, David A. Litton, Michael J. Maloney, Kevin W. Schlichting, John G. Smeggil, David B. Snow.
Application Number | 20100047075 12/610393 |
Document ID | / |
Family ID | 37865816 |
Filed Date | 2010-02-25 |
United States Patent
Application |
20100047075 |
Kind Code |
A1 |
Schlichting; Kevin W. ; et
al. |
February 25, 2010 |
Thermal Barrier Coating Compositions, Processes for Applying Same
and Articles Coated with Same
Abstract
A process of coating an article includes the steps of (1)
applying a ceramic compound to at least one surface of an article
to form a layer of ceramic compound; (2) applying at least one
inert compound upon the ceramic compound layer to form a protective
layer, wherein the at least one inert compound is composed of a
first inert compound having a cubic crystalline structure of
formula (I) A.sub.3B.sub.2X.sub.3O.sub.12, or a second inert
compound comprising a hexagonal crystalline structure of formula
(II) A.sub.4B.sub.6X.sub.6O.sub.26, or a mixture of the first inert
compound and the second inert compound; (3) optionally drying the
coated article; (4) optionally repeating steps (2) and (3); and (5)
heat treating the coated article.
Inventors: |
Schlichting; Kevin W.;
(South Glastonbury, CT) ; Litton; David A.; (West
Hartford, CT) ; Maloney; Michael J.; (Marlborough,
CT) ; Freling; Melvin; (West Hartford, CT) ;
Smeggil; John G.; (Simsbury, CT) ; Snow; David
B.; (Glastonbury, CT) |
Correspondence
Address: |
BACHMAN & LAPOINTE, P.C. (P&W)
900 CHAPEL STREET, SUITE 1201
NEW HAVEN
CT
06510-2802
US
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
37865816 |
Appl. No.: |
12/610393 |
Filed: |
November 2, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11328895 |
Jan 10, 2006 |
7622195 |
|
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12610393 |
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Current U.S.
Class: |
416/241B ;
204/192.12; 252/62; 415/200; 427/248.1; 427/256; 427/372.2;
427/380; 427/393.6; 427/453; 427/508; 427/585; 427/596; 428/332;
428/701; 428/702; 60/722; 60/740 |
Current CPC
Class: |
C04B 2235/75 20130101;
C04B 35/01 20130101; C23C 28/3215 20130101; C23C 28/325 20130101;
C04B 35/486 20130101; C04B 2235/764 20130101; C23C 28/345 20130101;
C04B 2235/762 20130101; C23C 26/00 20130101; C23C 28/322 20130101;
C04B 2235/76 20130101; C23C 28/3455 20130101; Y10T 428/26 20150115;
C04B 2235/767 20130101; C23C 28/042 20130101; Y02T 50/67 20130101;
C23C 28/321 20130101; C23C 28/36 20130101; Y02T 50/60 20130101;
C23C 28/048 20130101 |
Class at
Publication: |
416/241.B ;
427/372.2; 427/256; 428/701; 427/248.1; 427/453; 204/192.12;
427/585; 427/596; 427/508; 427/393.6; 427/380; 428/332; 428/702;
252/62; 415/200; 60/722; 60/740 |
International
Class: |
F01D 5/28 20060101
F01D005/28; C23C 14/34 20060101 C23C014/34; C23C 4/10 20060101
C23C004/10; B05D 3/02 20060101 B05D003/02; B32B 9/00 20060101
B32B009/00; B05D 7/00 20060101 B05D007/00; E04B 1/80 20060101
E04B001/80; F01D 9/02 20060101 F01D009/02; F23R 3/00 20060101
F23R003/00; F02C 7/22 20060101 F02C007/22 |
Claims
1. A process of coating an article, comprising: (1) applying a
ceramic compound; (2) applying at least one inert compound, wherein
said at least one inert compound comprises an inert compound
comprising a hexagonal crystalline structure of formula (II):
A.sub.4B.sub.6X.sub.6O.sub.26 (II) where A comprises at least one
of the metals selected from the group consisting of is Ca.sup.+2,
Mg.sup.+2, Fe.sup.+2, Na.sup.+, K.sup.+, Gd.sup.+3, Zr.sup.+4,
Hf.sup.+4, Y.sup.+2, Sc.sup.+2, Sc.sup.+3, In.sup.+3, La.sup.+2,
Ce.sup.+2, Pr.sup.+2, Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2,
Gd.sup.+2, Tb.sup.+2, Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2,
Yb.sup.+2, Lu.sup.+2, Sc.sup.+2, Y.sup.+2, Ti.sup.+2, Zr.sup.+2,
Hf.sup.+2, V.sup.+2, Ta.sup.+2, Cr.sup.+2, W.sup.+2, Mn.sup.+2,
Tc.sup.+2, Re.sup.+2, Fe.sup.+2, Os.sup.+2, Co.sup.+2, Ir.sup.+2,
Ni.sup.+2, Zn.sup.+2, Cd.sup.+2, and; where B comprises at least
one of the metals selected from the group consisting of Gd.sup.+3,
Y.sup.+2, Sc.sup.+2, In.sup.+3, Zr.sup.+4, Hf.sup.+4, Cr.sup.+3,
Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3,
W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3,
Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; where X comprises at least one
of the metals selected from the group consisting of Si.sup.+4,
Ti.sup.+4, Al.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3,
Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3,
Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and
Au.sup.+3; and where O is oxygen; and (3) heat treating said
article.
2. The process of claim 1, wherein the at least one inert compound
further comprises an inert compound comprising a cubic crystalline
structure of formula (I): A.sub.3B.sub.2X.sub.3O.sub.12 (I) where A
comprises at least one of the metals selected from the group
consisting of Ca.sup.+2, Gd.sup.+3, In.sup.+3, Mg.sup.+2, Na.sup.+,
K.sup.+, Fe.sup.+2, La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2,
Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2,
Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2,
Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2,
Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2,
Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and
Cd.sup.+2; where B comprises at least one of the metals selected
from the group consisting of Zr.sup.+4, Hf.sup.+4, Gd.sup.+3,
Al.sup.+3, Fe.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2,
Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2,
Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, In.sup.+3,
Sc.sup.+2, Y.sup.+2, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3,
Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3,
Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and
Au.sup.+3; where X comprises at least one of the metals selected
from the group consisting of Si.sup.+4, Ti.sup.+4, Al.sup.+4,
Fe.sup.+3, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3,
Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3,
Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; and
where O is oxygen.
3. The process of claim 1, wherein: the applying said ceramic
compound comprises applying to at least one surface of an article
to form a layer of ceramic compound; and the applying said at least
one inert compound comprises applying upon said ceramic compound
layer to form a protective layer.
4. The process of claim 1, wherein: the applying said ceramic and
the applying said at least one inert compound comprises grading the
ceramic compound and at least one inert compound upon at least one
surface of an article to form a graded thermal barrier coating.
5. The process of claim 4, wherein grading comprises forming said
graded thermal barrier coating having at least a surface where said
at least one inert compound is present in an amount of about 100
percent by weight of said graded thermal barrier coating.
6. The process of claim 1, further comprising (4) drying said
article prior to said heat treating (3).
7. The process of claim 6, further comprising (5) repeating steps
(2) and (4) prior to said heat treating (3).
8. The process of claim 1, wherein applying said ceramic compound
comprises applying said ceramic compound using a process selected
from the group consisting of physical vapor deposition, thermal
spraying, sputtering, sol gel and slurry.
9. The process of claim 8, wherein said physical vapor deposition
process is an electron beam physical vapor deposition process.
10. The process of claim 8, wherein said thermal spraying process
is a high velocity oxygen fuel thermal spraying process or an air
plasma thermal spraying process.
11. The process of claim 1, wherein heat treating comprises heating
said coated article at about 1200.degree. F. to about 2000.degree.
F. for about 30 minutes to about 360 minutes.
12. The process of claim 1, wherein said applying said at least one
inert compound comprises using a process selected from the group
consisting of physical vapor deposition, thermal spraying,
sputtering, sol gel, slurry, dipping, brushing, and painting.
13. The process of claim 12, wherein said physical vapor deposition
process is an electron beam physical vapor deposition process.
14. The process of claim 12, wherein said thermal spraying process
is an air plasma spraying process.
15. The process of claim 12, wherein said thermal spraying process
is a high velocity oxygen fuel thermal spraying process.
16. The process of claim 1, wherein the process for applying said
ceramic compound to said article is different than the process for
applying said inert compound to said ceramic compound layer.
17. The process of claim 1, wherein the process for applying said
ceramic compound to said article is the same as the process for
applying said inert compound to said ceramic compound layer.
18. The process of claim 1, further comprising the step of applying
a layer of bond coat material on at least one surface of said
article prior to applying said layer of ceramic compound.
19. The process of claim 18, wherein applying said bond coat layer
comprises a process selected from the group consisting of diffusion
processes, low pressure plasma-spray, air plasma-spray, sputtering,
cathodic arc, electron beam physical vapor deposition, high
velocity plasma spray processes, combustion processes, wire spray
processes, laser beam cladding, and electron beam cladding.
20. The process of claim 1, wherein applying said at least one
inert compound comprises the steps of: contacting said article with
a suspension of said inert compound, and at least one of each of a
dispersant, an ultra-violet curable resin and optionally a
surfactant at a temperature of about 68.degree. F. to about
150.degree. F. at a pressure of about 10 torr to about 100 torr for
about 2 minutes to about 5 minutes; curing said article using
ultra-violet light energy for about 10 seconds to about 60 seconds;
and heat treating said article at a temperature of about
750.degree. F. to about 1600.degree. F. for about 10 minutes to
about 90 minutes.
21. The process of claim 1, wherein applying said at least one
inert compound comprises the steps of: contacting said article with
a suspension of said inert compound, and at least one of each of a
dispersant, a heat curable resin and optionally a surfactant at a
temperature of about 68.degree. F. to about 150.degree. F. at a
pressure of about 10 torr to about 100 torr for about 2 minutes to
about 10 minutes; curing said article at a temperature of about
300.degree. F. for about 20 minutes to about 60 minutes; and heat
treating said article at a temperature of about 750.degree. F. to
about 1600.degree. F. for about 10 to about 90 minutes.
22. A thermal barrier coating comprising: a ceramic compound and at
least one inert compound, wherein said at least one inert compound
comprises a first inert compound comprising a hexagonal crystalline
structure of formula (II): A.sub.4B.sub.6X.sub.6O.sub.26 (II) where
A comprises at least one of the metals selected from the group
consisting of Ca.sup.+2, Mg.sup.+2, Na.sup.+, K.sup.+, Fe.sup.+2,
La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2, Pm.sup.+2, Sm.sup.+2,
Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2, Ho.sup.+2, Er.sup.+2,
Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2, Y.sup.+2, Ti.sup.+2,
Zr.sup.+2, Hf.sup.+2, V.sup.+2Ta.sup.+2, Cr.sup.+2, W.sup.+2,
Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2, Os.sup.+2, Co.sup.+2,
Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and Cd.sup.+2; where B comprises
at least one of the metals selected from the group consisting of
Gd.sup.+3, Y.sup.+2, Sc.sup.+2, In.sup.+3, Sc.sup.+2, Y.sup.+2,
Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3, Cr.sup.+3,
Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3, Co.sup.+3,
Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; where X comprises
at least one of the metals selected from the group consisting of
Si.sup.+4, Ti.sup.+4, Al.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; and where O is oxygen.
23. The thermal barrier coating of claim 22, wherein said at least
one inert compound comprises a second inert compound comprising a
cubic crystalline structure of formula (I):
A.sub.3B.sub.2X.sub.3O.sub.12 (I) where A comprises at least one of
the metals selected from the group consisting of Ca.sup.+2,
Gd.sup.+3, In.sup.+3, Mg.sup.+2, Na.sup.+, K.sup.+, Fe.sup.+2,
La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2, Pm.sup.+2, Sm.sup.+2,
Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2, Ho.sup.+2, Er.sup.+2,
Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2, Y.sup.+2, Ti.sup.+2,
Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2, Cr.sup.+2, W.sup.+2,
Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2, Os.sup.+2, Co.sup.+2,
Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and Cd.sup.+2; where B comprises
at least one of the metals selected from the group consisting of
Zr.sup.+4, Hf.sup.+4, Gd.sup.+3, Al.sup.+3, Fe.sup.+3, La.sup.+2,
Ce.sup.+2, Pr.sup.+2, Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2,
Gd.sup.+2, Tb.sup.+2, Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2,
Yb.sup.+2, Lu.sup.+2, In.sup.+3, Sc.sup.+2, Y.sup.+2, Cr.sup.+3,
Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3,
W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3,
Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; where X comprises at least one
of the metals selected from the group consisting of Si.sup.+4,
Ti.sup.+4, Al.sup.+4, Fe.sup.+3, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; and where O is oxygen,
24. The thermal barrier coating of claim 23, wherein said ceramic
compound comprises a stabilized zirconate or a stabilized
hafnate.
25. The thermal barrier coating of claim 23, wherein said ceramic
compound is selected from the group consisting of yttria stabilized
zirconia, calcia stabilized zirconia, magnesia stabilized zirconia,
yttria stabilized hafnia, calcia stabilized hafnia and magnesia
stabilized hafnia.
26. The thermal barrier coating of claim 23, wherein said second
inert compound is garnet.
27. The thermal barrier coating of claim 23, wherein said first
inert compound is oxyapatite.
28. The thermal barrier coating of claim 23, wherein said at least
one inert compound comprises a porosity of no more than about 30%
by volume of said at least one inert compound.
29. The thermal barrier coating of claim 23, wherein said at least
one inert compound comprises a porosity of no more than about 20%
by volume of said at least one inert compound.
30. A coated article comprising: an article comprising at least one
surface; and a thermal barrier coating according to claim 22
disposed thereupon.
31. The coated article of claim 30, wherein said first inert
compound comprises a first layer disposed upon a second layer
comprising said ceramic compound.
32. The coated article of claim 30, wherein said first inert
compound and said ceramic compound comprise a graded layer.
33. The coated article of claim 32, wherein at least at a surface
said at least one inert compound is present in an amount of about
100 percent by weight.
34. The coated article of claim 30, wherein said article is
selected from the group consisting of blades, vanes, stators, and
mid-turbine frames, seals, combustor panels, combustor chambers,
combustor bulkhead shields, disk side plates and fuel nozzle
guides.
35. The coated article of claim 34, wherein said at least one inert
compound comprises a layer having a thickness of about 5 mils to
about 15 mils.
36. The coated article of claim 30, further comprising a bond coat
material on at least one surface of said article prior to applying
said layer of ceramic based compound.
37. A coating, comprising: a reaction product of at least one
silica based material and a thermal barrier coating composition
comprising: a ceramic compound; and at least one inert compound,
wherein said at least one inert compound comprises a first inert
compound comprising hexagonal crystalline structure of formula
(II): A.sub.4B.sub.6X.sub.6O.sub.26 (II) where A comprises at least
one of the metals selected from the group consisting of is
Ca.sup.+2, Mg.sup.+2, Fe.sup.+2, Na.sup.+, K.sup.+, Gd.sup.+3,
Zr.sup.+4, Hf.sup.+4, Y.sup.+2, Sc.sup.+2, Sc.sup.+3, In.sup.+3,
La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2, Pm.sup.+2, Sm.sup.+2,
Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2, Ho.sup.+2, Er.sup.+2,
Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2, Y.sup.+2, Ti.sup.+2,
Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2, Cr.sup.+2, W.sup.+2,
Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2, Os.sup.+2, Co.sup.+2,
Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and Cd.sup.+2; where B comprises
at least one of the metals selected from the group consisting of
Gd.sup.+3, Y.sup.+2, Sc.sup.+2, In.sup.+3, Zr.sup.+4, Hf.sup.+4,
Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3, Cr.sup.+3,
Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3, Co.sup.+3,
Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; where X comprises
at least one of the metals selected from the group consisting of
Si.sup.+4, Ti.sup.+4, Al.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; and where O is oxygen.
38. The coating of claim 37 wherein said at least one inert
compound further comprises a second inert compound comprising a
cubic crystalline structure of formula (I):
A.sub.3B.sub.2X.sub.3O.sub.12 (I) where A comprises at least one of
the metals selected from the group consisting of Ca.sup.+2,
Gd.sup.+3, In.sup.+3, Mg.sup.+2, Na.sup.+, K.sup.+, Fe.sup.+2,
La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2, Pm.sup.+2, Sm.sup.+2,
Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2, Ho.sup.+2, Er.sup.+2,
Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2, Y.sup.+2, Ti.sup.+2,
Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2, Cr.sup.+2, W.sup.+2,
Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2, Os.sup.+2, Co.sup.+2,
Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and Cd.sup.+2; where B comprises
at least one of the metals selected from the group consisting of
Zr.sup.+4, Hf.sup.+4, Gd.sup.+3, Al.sup.+3, Fe.sup.+3, La.sup.+2,
Ce.sup.+2, Pr.sup.+2, Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2,
Gd.sup.+2, Tb.sup.+2, Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2,
Yb.sup.+2, Lu.sup.+2, In.sup.+3, Sc.sup.+2, Y.sup.+2, Cr.sup.+3,
Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3,
W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3,
Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; where X comprises at least one
of the metals selected from the group consisting of Si.sup.+4,
Ti.sup.+4, Al.sup.+4, Fe.sup.+3, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; and where O is oxygen.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a divisional application of Ser. No. 11/328,895,
filed Jan. 10, 2006, and entitled THERMAL BARRIER COATING
COMPOSITIONS, PROCESSES FOR APPLYING SAME AND ARTICLES COATED WITH
SAME, the disclosure of which is incorporated by reference herein
in its entirety as if set forth at length.
BACKGROUND
[0002] The disclosure relates to thermal barrier coating
compositions, processes for applying same and articles coated with
same. More particularly, the disclosure relates to thermal barrier
coating compositions designed to withstand sand infiltration,
processes for applying same and articles coated with same.
[0003] The degradation of turbomachinery parts due to sand related
distress of thermal barrier coatings ("TBCs") is a concern with
respect to all turbomachinery in use in the Middle East. Sand
related distress is responsible for the premature spallation of
TBCs and oxidation of turbomachinery and their parts. The mechanism
of such sand related distress is the penetration of the TBCs by
molten sand. During its useful life, sand may enter the
turbomachinery, agglomerate and become molten upon the TBC surface.
Typically the surface temperature of the turbomachinery is higher
than the melting point temperature of the sand. As a result, the
agglomerated sand particles become somewhat molten, penetrate the
TBC and reach the ceramic/metallic interface. The failure of the
TBC occurs by a combination of molten sand attacking the thermally
grown oxide at the ceramic/metallic interface as well as the
reduction in strain tolerance, of the fully infiltrated TBC, to
thermal cycling. Failure of the TBC occurs by spallation which
exposes the part's surface to the elements, thus causing the
accelerated oxidation of the turbomachinery part in conjunction
with molten sand attack.
[0004] Consequently, there exists a need for a thermal barrier
coating designed to resist sand related distress.
SUMMARY OF THE DISCLOSURE
[0005] In accordance with the present disclosure, a process of
coating an article broadly comprising (1) applying a ceramic
compound to at least one surface of an article to form a layer of
ceramic compound; (2) applying at least one inert compound upon the
ceramic compound layer to form a protective layer, wherein the at
least one inert compound comprises a first inert compound
comprising a cubic crystalline structure of formula (I):
A.sub.3B.sub.2X.sub.3O.sub.12 (I)
where A comprises at least one of the metals selected from the
group consisting of Ca.sup.+2, Gd.sup.+3, In.sup.+3, Mg.sup.+2,
Na.sup.+, K.sup.+, Fe.sup.+2, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
Sc.sup.+2, Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2,
Ta.sup.+2, Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2,
Fe.sup.+2, Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2,
and Cd.sup.+2; where B comprises at least one of the metals
selected from the group consisting of Zr.sup.+4, Hf.sup.+4,
Gd.sup.+3, Al.sup.+3, Fe.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
In.sup.+3, Sc.sup.+2, Y.sup.+2, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Fe.sup.+3, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3,
Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3,
Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and
Au.sup.+3; and where O is oxygen, or a second inert compound
comprising a hexagonal crystalline structure of formula (II):
A.sub.4B.sub.6X.sub.6O.sub.26 (II)
where A comprises at least one of the metals selected from the
group consisting of is Ca.sup.+2, Mg.sup.+2, Fe.sup.+2, Na.sup.+,
K.sup.+, Gd.sup.+3, Zr.sup.+4, Hf.sup.+4, Y.sup.+2, Sc.sup.+2,
Sc.sup.+3, In.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2,
Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2,
Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2,
Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2,
Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2,
Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and
Cd.sup.+2; where B comprises at least one of the metals selected
from the group consisting of Gd.sup.+3, Y.sup.+2, Sc.sup.+2,
In.sup.+3, Zr.sup.+4, Hf.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3,
Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3,
Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; and
where O is oxygen, or a mixture of the first inert compound and the
second inert compound; and (3) heat treating the article.
[0006] In accordance with the present disclosure, a process for
coating an article broadly comprising (1) grading a ceramic
compound and at least one inert compound upon at least one surface
of an article to form a graded thermal barrier coating, wherein the
at least one inert compound comprises a first inert compound
comprising a cubic crystalline structure of formula (I):
A.sub.3B.sub.2X.sub.3O.sub.12 (I)
where A comprises at least one of the metals selected from the
group consisting of Ca.sup.+2, Gd.sup.+3, In.sup.+3, Mg.sup.+2,
Na.sup.+, K.sup.+, Fe.sup.+2, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
Sc.sup.+2, Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2,
Ta.sup.+2, Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2,
Fe.sup.+2, Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2,
and Cd.sup.+2; where B comprises at least one of the metals
selected from the group consisting of Zr.sup.+4, Hf.sup.+4,
Gd.sup.+3, Al.sup.+3, Fe.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
In.sup.+3, Sc.sup.+2, Y.sup.+2, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Fe.sup.+3, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3,
Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3,
Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and
Au.sup.+3; and where O is oxygen, or a second inert compound
comprising a hexagonal crystalline structure of formula (II):
A.sub.4B.sub.6X.sub.6O.sub.26 (II)
where A comprises at least one of the metals selected from the
group consisting of is Ca.sup.+2, Mg.sup.+2, Fe.sup.+2, Na.sup.+,
K.sup.+, Gd.sup.+3, Zr.sup.+4, Hf.sup.+4, Y.sup.+2, Sc.sup.+2,
Sc.sup.+3, In.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2,
Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2,
Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2,
Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2,
Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2,
Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and
Cd.sup.+2; where B comprises at least one of the metals selected
from the group consisting of Gd.sup.+3, Y.sup.+2, Sc.sup.+2,
In.sup.+3, Zr.sup.+4, Hf.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3,
Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3,
Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; and
where O is oxygen, or a mixture of the first inert compound and the
second inert compound; and (2) heat treating the article.
[0007] In accordance with the present disclosure, a thermal barrier
coating broadly comprises a ceramic compound; and at least one
inert compound, wherein the at least one inert compound comprises a
first inert compound comprising a cubic crystalline structure of
formula (I):
A.sub.3B.sub.2X.sub.3O.sub.12 (I)
where A comprises at least one of the metals selected from the
group consisting of Ca.sup.+2, Gd.sup.+3, In.sup.+3, Mg.sup.+2,
Na.sup.+, K.sup.+, Fe.sup.+2, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
Sc.sup.+2, Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2,
Ta.sup.+2, Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2,
Fe.sup.+2, Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2,
and Cd.sup.+2; where B comprises at least one of the metals
selected from the group consisting of Zr.sup.+4, Hf.sup.+4,
Gd.sup.+3, Al.sup.+3, Fe.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
In.sup.+3, Sc.sup.+2, Y.sup.+2, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Fe.sup.+3, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3,
Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3,
Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and
Au.sup.+3; and where O is oxygen, or a second inert compound
comprising a hexagonal crystalline structure of formula (II):
A.sub.4B.sub.6X.sub.60.sub.26 (II)
where A comprises at least one of the metals selected from the
group consisting of is Ca.sup.+2, Mg.sup.+2, Fe.sup.+2, Na+,
K.sup.+, Gd.sup.+3, Zr.sup.+4, Hf.sup.+4, Y.sup.+2, Sc.sup.+2,
Sc.sup.+3, In.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2,
Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2,
Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2,
Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2,
Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2,
Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and
Cd.sup.+2; where B comprises at least one of the metals selected
from the group consisting of Gd.sup.+3, Y.sup.+2, Sc.sup.+2,
In.sup.+3, Zr.sup.+4, Hf.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; and
where O is oxygen, or a mixture of the first inert compound and the
second inert compound.
[0008] In accordance with the present disclosure, a coated article
broadly comprises an article comprising at least one surface
comprising a thermal barrier coating disposed thereupon, wherein
the thermal barrier coating broadly comprises a ceramic compound;
and at least one inert compound comprising a first inert compound
comprising a cubic crystal structure of formula (I):
A.sub.3B.sub.2X.sub.3O.sub.12 (I)
where A comprises at least one of the metals selected from the
group consisting of Ca.sup.+2, Gd.sup.+3, In.sup.+3, Mg.sup.+2,
Na.sup.+, K.sup.+, Fe.sup.+2, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
Sc.sup.+2, Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2,
Ta.sup.+2, Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2,
Fe.sup.+2, Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2,
and Cd.sup.+2; where B comprises at least one of the metals
selected from the group consisting of Zr.sup.+4, Hf.sup.+4,
Gd.sup.+3, Al.sup.+3, Fe.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
In.sup.+3, Sc.sup.+2, Y.sup.+2, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Fe.sup.+3, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3,
Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3,
Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and
Au.sup.+3; and where O is oxygen, or a second inert compound
comprising a hexagonal crystalline structure of formula (II):
A.sub.4B.sub.6X.sub.6O.sub.26 (II)
where A comprises at least one of the metals selected from the
group consisting of is Ca.sup.+2, Mg.sup.+2, Fe.sup.+2, Na.sup.+,
K.sup.+, Gd.sup.+3, Zr.sup.+4, Hf.sup.+4, Y.sup.+2, Sc.sup.+2,
Sc.sup.+3, In.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2,
Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2,
Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Y.sup.+2,
Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2, Cr.sup.+2,
W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2, Os.sup.+2,
Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and Cd.sup.+2; where B
comprises at least one of the metals selected from the group
consisting of Gd.sup.+3, Y.sup.+2, Sc.sup.+2, In.sup.+3, Zr.sup.+4,
Hf.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3,
Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3,
Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; where X
comprises at least one of the metals selected from the group
consisting of Si.sup.+4, Ti.sup.+4, Al.sup.+4, Cr.sup.+3,
Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3,
W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3,
Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; and where O is oxygen, or a
mixture of the first inert compound and the second inert
compound.
[0009] In accordance with the present disclosure, a coating broadly
comprises a reaction product of at least one silicate based
material and a thermal barrier coating composition broadly
comprising a ceramic compound; and at least one inert compound,
wherein said at least one inert compound broadly comprises a first
inert compound broadly comprising a cubic crystalline structure of
formula (I):
A.sub.3B.sub.2X.sub.3O.sub.12 (I)
where A comprises at least one of the metals selected from the
group consisting of Ca.sup.+2, Gd.sup.+3, In.sup.+3, Mg.sup.+2,
Na.sup.+, K.sup.+, Fe.sup.+2, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
Sc.sup.+2, Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2,
Ta.sup.+2, Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2,
Fe.sup.+2, Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2,
and Cd.sup.+2; where B comprises at least one of the metals
selected from the group consisting of Zr.sup.+4, Hf.sup.+4,
Gd.sup.+3, Al.sup.+3, Fe.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
In.sup.+3, Sc.sup.+2, Y.sup.+2, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Fe.sup.+3, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3,
Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3,
Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and
Au.sup.+3; and where O is oxygen, or a second inert compound
comprising a hexagonal crystalline structure of formula (II):
A.sub.4B.sub.6X.sub.6O.sub.26 (II)
where A comprises at least one of the metals selected from the
group consisting of is Ca.sup.+2, Mg.sup.+2, Fe.sup.+2, Na.sup.+,
K.sup.+, Gd.sup.+3, Zr.sup.+4, Hf.sup.+4, Y.sup.+2, Sc.sup.+2,
Sc.sup.+3, In.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2,
Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2,
Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2,
Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2,
Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2,
Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and
Cd.sup.+2; where B comprises at least one of the metals selected
from the group consisting of Gd.sup.+3, Y.sup.+2, Sc.sup.+2,
In.sup.+3, Zr.sup.+4, Hf.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3,
Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3,
Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; and
where O is oxygen, or a mixture of said first inert compound and
said second inert compound.
[0010] The details of one or more embodiments are set forth in the
accompanying drawings and the description below. Other features,
objects, and advantages will be apparent from the description and
drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a flowchart representing one process of the
present disclosure;
[0012] FIG. 2 is a flowchart representing another process of the
present disclosure;
[0013] FIG. 3 is a representation of an article coated with at
least one layer of a ceramic compound and at least one layer of at
least one inert compound of the present disclosure;
[0014] FIG. 4 is a representation of an article coated with at
least one graded layer comprising at least one ceramic compound and
at least one inert compound of the present disclosure;
[0015] FIG. 5 is a representation of an article coated with an
optional bond coat layer, at least one layer of a ceramic compound
and at least one layer of at least one inert compound of the
present disclosure; and
[0016] FIG. 6 is representation of an article coated with an
optional bond coat layer, at least one graded layer comprising at
least one ceramic compound and at least one inert compound of the
present disclosure.
[0017] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0018] As used herein, the term "inert compound" means a compound
having either a cubic crystalline structure or a hexagonal
crystalline structure that exhibits thermodynamic and chemical
equilibrium when combined with or makes contact with a ceramic
compound, any silicate based material such as, but not limited to,
sand, calcia magnesia alumina silicate and the like.
[0019] The thermal barrier coating (hereinafter referred to as
"TBC") of the present disclosure is designed to prevent at least
one component of sand such as, but not limited to, calcium magnesia
alumina silicate (hereinafter referred to as "CMAS"), from
penetrating the ceramic compound of the TBC. By
preventing/resisting such penetration, premature oxidation of the
article and spallation of the TBC are prevented/resisted. Sand
generally comprises at least CMAS as well as other components such
as, but not limited to, sodium, iron, potassium and the like,
depending upon the geographical and geological conditions of the
sand. Sands containing iron and CMAS also pose similar problems as
described above due to iron-CMAS interaction and penetration to the
metallic/ceramic interface of the coated article. The TBC comprises
a ceramic compound graded with or mechanically and/or chemically
bonded, adhered or affixed to at least one inert compound having
either a cubic crystalline structure or a hexagonal crystalline
structure.
[0020] Referring now to FIGS. 1 and 2, a flowchart representing one
of the processes of the present disclosure is shown. An article may
be provided and may be coated with an optional bond coat material
at a box 10 of FIG. 1 and at a box 30 of FIG. 2. The bond coat
material may comprise a formula MCrAlY. MCrAlY refers to known
metal coating systems in which M denotes nickel, cobalt, iron,
their alloys, and mixtures thereof; Cr denotes chromium; Al denotes
aluminum; and Y denotes yttrium. MCrAlY materials are often known
as overlay coatings because they are applied in a predetermined
composition and do not interact significantly with the substrate
during the deposition process. For some non-limiting examples of
MCrAlY materials see U.S. Pat. No. 3,528,861 which describes a
FeCrAlY coating as does U.S. Pat. No. 3,542,530. In addition, U.S.
Pat. No. 3,649,225 describes a composite coating in which a layer
of chromium is applied to a substrate prior to the deposition of a
MCrAlY coating. U.S. Pat. No. 3,676,085 describes a CoCrAlY overlay
coating while U.S. Pat. No. 3,754,903 describes a NiCoCrAlY overlay
coating having particularly high ductility. U.S. Pat. No. 4,078,922
describes a cobalt base structural alloy which derives improved
oxidation resistance by virtue of the presence of a combination of
hafnium and yttrium. A preferred MCrAlY bond coat composition is
described in U.S. Pat. No. Re. 32,121, which is assigned to the
present Assignee and incorporated herein by reference, as having a
weight percent compositional range of 5-40 Cr, 8-35 Al, 0.1-2.0 Y,
0.1-7 Si, 0.1-2.0 Hf, balance selected from the group consisting of
Ni, Co and mixtures thereof. See also U.S. Pat. No. 4,585,481,
which is also assigned to the present Assignee and incorporated
herein by reference.
[0021] The bond coat material may also comprise Al, PtAl and the
like, that are often known in the art as diffusion coatings. In
addition, the bond coat material may also comprise Al, PtAl, MCrAlY
as described above, and the like, that are often known in the art
as cathodic arc coatings.
[0022] The MCrAlY bond coat may be applied by any method capable of
producing a dense, uniform, adherent coating of the desired
composition, such as, but not limited to, an overlay bond coat,
diffusion bond coat, cathodic arc bond coat, etc. Such techniques
may include, but are not limited to, diffusion processes (e.g.,
inward, outward, etc.), low pressure plasma-spray, air
plasma-spray, sputtering, cathodic arc, electron beam physical
vapor deposition, high velocity plasma spray techniques (e.g.,
HVOF, HVAF), combustion processes, wire spray techniques, laser
beam cladding, electron beam cladding, etc.
[0023] The particle size for the bond coat may be of any suitable
size, and in embodiments may be between about 15 microns (0.015 mm)
and about 60 microns (0.060 mm) with a mean particle size of about
25 microns (0.025 mm). The bond coat 30 may be applied to any
suitable thickness, and in embodiments may be about 5 mils (0.127
mm) to about 10 mils (0.254 mm) thick. In some embodiments, the
thickness may be about 6 mils (0.152 mm) to about 7 mils (0.178 mm)
thick.
[0024] After applying the optional bond coat layer to the article,
a ceramic compound may be applied upon the optional bond coat layer
or at least one surface of the coated article at a box 12 of FIG.
1. The ceramic compound may be applied as a TBC to the article
using any number of processes known to one of ordinary skill in the
art. Suitable application processes include, but are not limited
to, physical vapor deposition (e.g., electron beam), thermal spray
(e.g., air plasma, high velocity oxygen fuel), sputtering, sol gel,
slurry, combinations comprising at least one of the foregoing
application processes, and the like.
[0025] Once the TBC is applied, at least one inert compound may be
applied upon the TBC at a box 14 of FIG. 1. The at least one inert
compound may be applied to the TBC using any number of processes
known to one of ordinary skill in the art. Suitable application
processes include, but are not limited to, physical vapor
deposition (e.g., electron beam), thermal spray (e.g., air plasma,
high velocity oxygen fuel), sputtering, sol gel, slurry,
combinations comprising at least one of the foregoing application
processes, and the like.
[0026] The TBC and the at least one inert compound may be applied
using the same processes, for example, applying both the TBC and
the at least one inert compound using a physical vapor deposition
process. The TBC and the at least one inert compound may be applied
separately such that a TBC may be formed and then a layer of at
least one inert compound may be formed upon the TBC. The layers of
TBC and at least one inert compound may be mechanically and/or
chemically bonded, adhered and/or affixed to as a result of such
application processes. Or, the TBC and the at least one inert
compound may be applied in combination at a box 32 of FIG. 2. For
example, the ceramic compound and the at least one inert compound
may be applied together and graded as known to one of ordinary
skill in the art. Grading the ceramic compound and the at least one
inert compound may form a coating where the at least one inert
compound may be present in an amount of about 100% at least at the
surface of the graded coating.
[0027] In another embodiment of this process of the present
disclosure, the TBC and the at least one inert compound may be
applied using different processes at boxes 12 and 14 of FIG. 1, for
example, applying the TBC using a physical vapor deposition process
and applying the at least one inert compound using a thermal
spraying process. The TBC and the at least one inert compound may
then be applied separately to form a TBC and then a layer of at
least one inert compound upon the TBC. The layers of TBC and at
least one inert compound may be mechanically and/or chemically
bonded, adhered and/or affixed to as a result of such application
processes.
[0028] In an alternative embodiment, when applying the at least one
inert compound using a solution based process such as sol gel and
slurry (e.g., dipping, brushing, painting, etc.), the TBC coated
article may be contacted with a solution comprising a suspension at
box 14 of FIG. 1. The suspension may comprise a solvent, at least
one inert compound, and at least one ultra-violet or heat curable
resin, at least one dispersant and in the alternative, or in
addition to, at least one surfactant. When the TBC comprises
columnar structures with interstices, the article may contact the
suspension at a temperature of about 68.degree. F. (20.degree. C.)
to about 150.degree. F. (66.degree. C.) and initially under a
vacuum of about 10 torr (0.19 psi) to about 100 torr (1.9 psi) for
about 2 minutes to about 5 minutes at which point the pressure may
then be adjusted to atmospheric pressure, that is, about 760 torr
(14.7 psi). When the TBC comprises a tortuous, interconnected
porosity, the article may contact the suspension at a temperature
of about 68.degree. F. (20.degree. C.) to about 150.degree. F.
(66.degree. C.) and initially under a vacuum of about 10 torr (0.19
psi) to about 100 torr (1.9 psi) for about 2 to about 10 minutes at
which point the pressure may then be adjusted to atmospheric
pressure. One of ordinary skill in the art will recognize this
process is also known as vacuum impregnation. The goal is to draw
out the air present in the interstices or porosity of the TBC in
order to make room for the metal to enter. To further draw out the
air the article may be agitated, for example, moved within the
suspension, to force out any air remaining.
[0029] The coated article may then be treated with ultra-violet
light energy or heat to cure the resin at a box 16 of FIG. 1. The
coated article may be treated with ultra-violet light energy for
about 10 second to about 60 seconds using processes known to one of
ordinary skill in the art. In the alternative, when utilizing a
heat curable resin, the coated article may be treated at a
temperature of about 300.degree. F. for about 20 minutes to about
60 minutes in an oven, or similar suitable apparatus, as known to
one of ordinary skill in the art at box 16 of FIG. 1.
[0030] After curing the TBC coated article, the article may be
dried to remove, that is, evaporate or burn off, the excess
solvent, dispersant and/or resin materials. The article may be
dried using any processes known to one of ordinary skill in the art
suitable for use herein. Suitable drying processes include, but are
not limited to, air drying, drying under pressure, drying under a
heating element, combinations comprising at least one of the
foregoing processes, and the like. The amount of time necessary to
dry the article depends upon several factors and, in particular,
the solvent of the suspension. For example, the TBC coated article
may be dried at a temperature of about 750.degree. F. to about
1600.degree. F. for about 10 minutes to about 90 minutes in order
to burn off the resin materials.
[0031] Suitable solvents for use in the suspension include, but are
not limited to, water, alcohols, combinations comprising at least
one of the foregoing solvents, and the like. Suitable dispersants
may comprise organic dispersants which may evaporate and/or burn
off easily during the drying step. Representative organic
dispersants include, but are not limited to, polymethylmethacrylate
(also known as "pmma"), polyvinyl alcohol, and the like. The
aforementioned `at least one dispersant` may be present in an
amount of about 0.25% to about 3% by volume of the suspension.
[0032] An ultra-violet curable resin for use herein may comprise a
resin, at least one of each of the following: initiator, additive,
modifier, monomer, and oligomer. The resin may comprise a urethane
based resin that may require one or more curing steps, for example,
a dual curing resin. The at least one initiator may comprise a
substance that initiates polymerization of the resin when exposed
to ultra-violet light energy of a compatible wavelength. For a dual
curing resin, two initiators may be required such that the second
initiator may require heat in order to facilitate polymerization of
the resin. Dual cure resins are effective when curing coatings
where the ultra-violet light energy may not reach the resin
material, such as in between the columnar or microcolumnar
structures of the coating or at a certain depth in the coating as
known to one of ordinary skill in the art. The at least one
additive may comprise a filler chemical capable of enhancing one or
more resin properties such as, but not limited to, flow rate,
wetting, color, fluorescence and achieving tack-free surfaces. The
at least one modifier may comprise a substance capable of
increasing the durability, for example, impact resistance, crack
resistance and the like, of the resin. The at least one monomer may
comprise at least one single unit of a polymer capable of providing
and/or enhancing adhesion to surface materials, for example, the
adhesion of the resin to the surface of the article being coated.
The at least one oligomer is recognized as the backbone of the
resin and may comprise a polymer unit comprising about 6 to about
40 monomer units that imparts the basic properties of the
ultra-violet curable resin such as, but not limited to, hardness,
elongation, chemical resistance, and the like. In the alternative,
the ultra-violet curable resin may be substituted with at least one
heat curable resin as known to one of ordinary skill in the
art.
[0033] After the TBC and at least one inert compound have been
applied to the article, the coated article may be dried at a
temperature of about 300.degree. F. to about 750.degree. F. for an
amount of time necessary to dry the coating(s) and, if necessary,
remove, that is, evaporate and/or burn off, the solvent of the
application process at a box 18 of FIG. 1 and at a box 34 of FIG.
2. When applying the TBC using any thermal spray process, the
drying step may become optional and/or omitted from the process.
After drying the coating(s) and/or removing the solvent, boxes 12,
14, 16 and 18 of FIG. 1 or boxes 32 and 34 of FIG. 2 may be
repeated as often as necessary in order to achieve the desired
properties of the coating(s). Such properties include, but are not
limited to, thickness, density, porosity and the like.
[0034] To facilitate the formation of the respective crystalline
structures of the at least one inert compound, the coated article
may be heat treated at a temperature of about 1200.degree. F.
(649.degree. C.) to about 2000.degree. F. (1093.degree. C.) for
about 30 minutes to about 360 minutes at a box 22 of FIG. 1 and a
box 38 of FIG. 2. As the at least one inert compound dries under
the aforementioned heat treatment conditions, the respective
crystalline structures of the inert compounds form under such
conditions.
[0035] The thermal barrier composition of the present disclosure
formed from the aforementioned processes may comprise the
aforementioned ceramic compound and at least one inert compound,
including at least one metal oxide formed during the ceramic
barrier composition application process. The at least one inert
compound may comprise a first inert compound, a second inert
compound or a mixture of both the first inert compound and the
second inert compound. More than two inert compounds may also be
utilized.
[0036] The at least one inert compound may comprise an inert
compound having a cubic crystalline structure comprising a formula
(I):
A.sub.3B.sub.2X.sub.3O.sub.12 (I)
where A comprises at least one of the metals selected from the
group consisting of Ca.sup.+2, Gd.sup.+3, In.sup.+3, Mg.sup.+2,
Na.sup.+, K.sup.+, Fe.sup.+2, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
Sc.sup.+2, Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2,
Ta.sup.+2, Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2,
Fe.sup.+2, Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2,
and Cd.sup.+2; where B comprises at least one of the metals
selected from the group consisting of Zr.sup.+4, Hf.sup.+4,
Gd.sup.+3, Al.sup.+3, Fe.sup.+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2,
Nd.sup.+2, Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2,
Dy.sup.+2, Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2,
Ac.sup.+2, Th.sup.+2, Pa.sup.+2, U.sup.+2, Np.sup.+2, Pu.sup.+2,
Am.sup.+2, Cm.sup.+2, Bk.sup.+2, Cf.sup.+2, Es.sup.+2, Fm.sup.+2,
Md.sup.+2, No.sup.+2, Lr.sup.+2, In.sup.+3, Sc.sup.+2, Y.sup.+2,
Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3, Cr.sup.+3,
Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3, Co.sup.+3,
Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; where X comprises
at least one of the metals selected from the group consisting of
Si.sup.+4, Ti.sup.+4, Al.sup.+4, Fe.sup.+3, Cr.sup.+3, Sc.sup.+3,
Y.sup.+3, V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3,
Mn.sup.+3, Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3,
Ni.sup.+3, and Au.sup.+3; and where O is oxygen.
[0037] The at least one inert compound may also comprise an inert
compound having a hexagonal crystalline structure comprising a
formula (II):
A.sub.4B.sub.6X.sub.6O.sub.26 (II)
where A comprises at least one of the metals selected from the
group consisting of is Ca+2, Mg+2, Fe+2, Na+, K+, Gd+3, Zr+4, Hf+4,
Y+2, Sc+2, Sc+3, In+3, La.sup.+2, Ce.sup.+2, Pr.sup.+2, Nd.sup.+2,
Pm.sup.+2, Sm.sup.+2, Eu.sup.+2, Gd.sup.+2, Tb.sup.+2, Dy.sup.+2,
Ho.sup.+2, Er.sup.+2, Tm.sup.+2, Yb.sup.+2, Lu.sup.+2, Sc.sup.+2,
Y.sup.+2, Ti.sup.+2, Zr.sup.+2, Hf.sup.+2, V.sup.+2, Ta.sup.+2,
Cr.sup.+2, W.sup.+2, Mn.sup.+2, Tc.sup.+2, Re.sup.+2, Fe.sup.+2,
Os.sup.+2, Co.sup.+2, Ir.sup.+2, Ni.sup.+2, Zn.sup.+2, and
Cd.sup.+2; where B comprises at least one of the metals selected
from the group consisting of Gd.sup.+3, Y.sup.30 2, Sc.sup.+2,
In.sup.+3, Zr.sup.+4, Hf.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3,
V.sup.+3, Nb.sup.+3, Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3,
Fe.sup.+3, Ru.sup.+3, Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3,
and Au.sup.+3; where X comprises at least one of the metals
selected from the group consisting of Si.sup.+4, Ti.sup.+4,
Al.sup.+4, Cr.sup.+3, Sc.sup.+3, Y.sup.+3, V.sup.+3, Nb.sup.+3,
Cr.sup.+3, Mo.sup.+3, W.sup.+3, Mn.sup.+3, Fe.sup.+3, Ru.sup.+3,
Co.sup.+3, Rh.sup.+3, Ir.sup.+3, Ni.sup.+3, and Au.sup.+3; and
where O is oxygen.
[0038] The at least one inert compound may also comprise a mixture
of the inert compound of formula (I) and the inert compound of
formula (II). In at least one embodiment, the inert compound of
formula (I) may comprise garnet. In at least one other embodiment,
the inert compound of formula (II) may comprise oxyapatite. In yet
at least one other embodiment, the aforementioned mixture may
comprise both garnet and oxyapatite. Depending upon the application
process, the at least one inert compound may be in a form suitable
for use in the intended application process. For example, the at
least one inert compound may be a fine particulate for use in sol
gel, slurry or dipping processes, or may be a coarse particulate
for use in a thermal spraying or physical vapor deposition
processes, or may comprise a solid target for use in a sputtering
process.
[0039] The resultant layer of the at least one inert compound, or
the resultant graded layer of the ceramic compound and the at least
one inert compound, may have a porosity of no more than about 30%
by volume of the at least one inert compound or the graded layer,
and preferably no more than about 20% by volume of the at least one
inert compound or the graded layer. The inert compounds of the
present disclosure are inert or non-reactive to all of the ceramic
compounds currently used as thermal barrier compositions. In
addition, the inert compounds are also inert or non-reactive to at
least one component of the molten sand as described above. The
inert properties, hardness of garnet and oxyapatite (alone or in
combination), and resultant porosity values are enough to prevent
the sand and CMAS from penetrating the TBC of the present
disclosure and reaching the surface of the coated article.
[0040] Referring now to FIGS. 3-6, the resultant product in all of
the processes of the present disclosure may be an article 40 coated
with at least one layer of a ceramic compound 42 and at least one
layer of at least one inert compound 44 (See FIG. 3), or in the
alternative, may be an article 50 coated with an optional bond coat
layer 56, at least one layer of a ceramic compound 52 and at least
one layer of at least one inert compound 54 (See FIG. 4). In
another embodiment, an article 60 coated with at least one graded
layer 62 comprising both the ceramic compound and at least one
inert compound (See FIG. 5), or in the alternative, may be an
article 70 coated with an optional bond coat layer 76, at least one
graded layer 72 comprising both the ceramic compound and at least
one inert compound (See FIG. 6). As described earlier, the article
may comprise a part used in turbomachinery applications such as,
but not limited to, any part having an airfoil, any part having a
seal, airfoils, seals, and the like. As known to one of ordinary
skill in the art, TBC coatings for turbomachinery parts having
seals, or seals in general, are typically thicker than TBC coatings
for turbomachinery parts having an airfoil, or airfoils in general.
Likewise, the coated articles of the present disclosure adhere to
these industry standards known to one of ordinary skill in the
art.
[0041] For example, the article may include, but is not limited to
blades, vanes, stators, mid-turbine frames, and the like. And, in
yet another example, the article may include, but is not limited
to, seals, combustor panels, combustor chambers, combustor bulkhead
shields, disk side plates, fuel nozzle guides, and the like.
[0042] Generally, coated articles having an airfoil, or a coated
airfoil in general, of the present disclosure generally comprise a
coating of the present disclosure of about 0.25 mils to about 15
mils in thickness. The coating layer of such thickness may comprise
a graded layer or may comprise a layer of the at least one inert
compound alone. And, generally, coated articles having a seal, or a
coated seal in general, of the present disclosure comprise a
coating of the present disclosure of about 0.25 mils to about 50
mils in thickness. The coating layer of such thickness may comprise
a graded layer or may comprise a layer of the at least one inert
compound alone. These ranges of coating thicknesses for such coated
articles of the present disclosure may be broadened or narrowed
depending upon the particular application of the article as will be
recognized and understood by one of ordinary skill in the art.
[0043] The garnet and/or oxyapatite materials alone or in
combination with the TBC coatings described herein may react may
react with the CMAS, and/or other components, of the molten sand.
The reaction product of the CMAS and garnet and/or oxyapatite may
comprise further at least one reaction product as more than one
reaction product may form during the useful life of the coated
article of the present disclosure. For example, a garnet and/or
oxyapatite layered or combined with a TBC such as 7YSZ may react
with CMAS to form a reaction product comprising at least a complex
oxide compound with the garnet crystalline structure and coexist
with silicate oxyapatites, including at least simple oxides, less
complex oxides and glass.
[0044] The reaction product or products form throughout the
entirety of the garnet and/or oxyapatite, alone or in combination
with the TBC, as the garnet and/or oxyapatite may be dispersed
throughout the TBC and the molten sand penetrates through to the
coated article's metal/ceramic interface.
[0045] The at least one reaction product forms a reaction barrier
or sealant composition as a layer upon the TBC or throughout the
TBC. The resultant sealant composition remains present as the TBC
experiences typical wear and tear, for example, abrasion, erosion,
spallation, etc., consistent with general use. Thus, as the TBC
wears during its useful life, the sealant composition reforms,
remains intact and effectively takes the place of and/or becomes
the TBC. The resultant sealant layer may also exhibit the desired
porosity of no more than about 30% by volume of the TBC, and
preferably no more than about 20% by volume of the TBC.
[0046] One or more embodiments have been described. Nevertheless,
it will be understood that various modifications may be made
without departing from the spirit and scope of the disclosure.
Accordingly, other embodiments are within the scope of the
following claims.
* * * * *