U.S. patent application number 10/814213 was filed with the patent office on 2004-12-23 for thermal barrier composition.
Invention is credited to Garrett, David William, Simendinger, William H. III.
Application Number | 20040260018 10/814213 |
Document ID | / |
Family ID | 33299863 |
Filed Date | 2004-12-23 |
United States Patent
Application |
20040260018 |
Kind Code |
A1 |
Simendinger, William H. III ;
et al. |
December 23, 2004 |
Thermal barrier composition
Abstract
The thermal barrier composition of the present invention
provides a glassy matrix comprising an alkoxy-functionalized
siloxane and a functionally-terminated silane or siloxane,
polymethylsilsesquioxane dissolved in a crosslinking agent, and
optionally a filler and/or hollow glass microspheres.
Inventors: |
Simendinger, William H. III;
(Raleigh, NC) ; Garrett, David William; (Raleigh,
NC) |
Correspondence
Address: |
MYERS BIGEL SIBLEY & SAJOVEC
PO BOX 37428
RALEIGH
NC
27627
US
|
Family ID: |
33299863 |
Appl. No.: |
10/814213 |
Filed: |
March 31, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60461800 |
Apr 10, 2003 |
|
|
|
Current U.S.
Class: |
524/860 ; 252/62;
528/33; 528/34 |
Current CPC
Class: |
C08G 77/18 20130101;
C09D 183/04 20130101; C09D 183/04 20130101; C08L 83/04 20130101;
Y10T 428/31663 20150401; C08G 77/14 20130101; C08L 83/04 20130101;
C09D 5/18 20130101; C08L 83/00 20130101; C08L 83/00 20130101 |
Class at
Publication: |
524/860 ;
252/062; 528/033; 528/034 |
International
Class: |
C08L 083/04; E04B
001/74 |
Claims
That which is claimed is:
1. A thermal barrier coating composition (a) a glassy matrix
comprising an alkoxy-functionalized siloxane and a
functionally-terminated silane or siloxane; (b)
polymethylsilsesquioxane dissolved in a crosslinking agent; (c)
optionally, a filler, and (d) optionally hollow glass
microspheres.
2. The thermal barrier coating composition according to claim 1,
wherein the alkoxy-functionalized siloxane is selected from the
group consisting of polydiethoxysiloxane, polydimethoxysiloxane,
tetramethoxysiloxane and tetraethoxysiloxane and the
functionally-terminated siloxane is an epoxy-functionalized
polydiethoxysiloxane.
3. The thermal barrier coating composition according to claim 1,
wherein the crosslinking agent is titanium isopropoxide.
4. The thermal barrier coating compositiong according to claim 1,
wherein the filler is selected from the group consisting of fumed
silica, mica, kaolin, bentonite, talc, zinc oxides, iron oxides and
pigments.
5. The thermal barrier coating composition according to claim 1,
wherein the glassy matrix is crosslinked using a titanium or tin
catalyst.
6. The thermal barrier coating composition according to claim 5,
wherein the titanium or tin catalyst is selected from the group
consisting of titanium methoxide, titanium ethoxide, titanium
isopropoxide, titanium propoxide, titanium butoxide, titanium
diisopropoxide (bis 2,4-pentanedionate), titanium diisopropoxide
bis(ethylacetoacetao) titanium ethylhexoxide, dibutyl tin
diacetate, dibutyltin laurate, dimethyl tin dineodecanoate, dioctyl
dilauryl tin, and dibutyl butoxy chlorotin, and mixtures
thereof.
7. The thermal barrier coating composition according to claim 1,
further comprising an anti-corrosion agent.
8. A substrate coated with a thermal barrier composition comprising
a glassy matrix comprising an alkoxy-functionalized siloxane and a
functionally-terminated silane or siloxane,
polymethylsilsesquioxane dissolved in a crosslinking agent,
optionally, a filler, and optionally hollow glass microspheres.
9. The substrate according to claim 8, wherein the substrate is
selected from the group consisting of steel, stainless steel,
titanium, aluminum, magnesium and zinc.
10. The substrate according to claim 8, wherein the
alkoxy-functionalized siloxane is selected from the group
consisting of polydiethoxysiloxane, polydimethoxysiloxane,
tetramethoxysilane and tetraethoxysilane and the
functionally-terminated siloxane is an epoxy-functionalized
polydiethoxysiloxane.
11. The substrate according to claim 8, wherein the crosslinking
agent is titanium isopropoxide.
12. The substrate according to claim 8, wherein the filler is
selected from the group consisting of fumed silica, mica, kaolin,
bentonite, talc, zinc oxides, iron oxides, and pigments.
13. The substrate according to claim 8, wherein the glassy matrix
is crosslinked using a titanium or tin catalyst.
14. The substrate according to claim 13, wherein the titanium or
tin catalyst is selected from the group consisting of titanium
methoxide, titanium ethoxide, titanium isopropoxide, titanium
propoxide, titanium butoxide, titanium diisopropoxide (bis
2,4-pentanedionate), titanium diisopropoxide bis(ethylacetoacetao)
titanium ethylhexoxide, dibutyl tin diacetate, dibutyltin laurate,
dimethyl tin dineodecanoate, dioctyl dilauryl tin, and dibutyl
butoxy chlorotin, and mixtures thereof.
15. The substrate according to claim 8, further comprising an
anti-corrosion agent.
16. A method of forming a thermal barrier composition comprising
the steps of (a) dissolving polymethylsilsesquioxane in a
crosslinking agent; (b) mixing a glass matrix comprising an
alkoxy-functionalized siloxane and a functionally-terminated silane
with a tin or titanium catalyst to terminate the silanol groups on
the end of the siloxane; and (c) mixing (a) and (b) together.
17. The method according to claim 16, including adding filler or
glass microspheres to the dissolved polymethylsilsesquioxane of
step (a) or the mixture of step (c).
18. The method according to claim 16, wherein the
alkoxy-functionalized siloxane is selected from the group
consisting of polydiethoxysiloxane, polydimethoxysiloxane,
tetramethoxysilane and tetraethoxysilane and the
functionally-terminated siloxane is an epoxy-functionalized
polydiethoxysiloxane.
19. The method according to claim 16, wherein the crosslinking
agent is titanium isopropoxide.
20. The method according to claim 16, wherein the filler selected
from the group consisting of fumed silica, mica, kaolin, bentonite,
talc, zinc oxides, zinc phosphates, iron oxides and pigments.
21. The method according to claim 16, wherein the titanium or tin
catalyst is selected from the group consisting of titanium
methoxide, titanium ethoxide, titanium isopropoxide, titanium
propoxide, titanium butoxide, titanium diisopropoxide (bis
2,4-pentanedionate), titanium diisopropoxide bis(ethylacetoacetao)
titanium ethylhexoxide, dibutyl tin diacetate, dibutyltin laurate,
dimethyl tin dineodecanoate, dioctyl dilauryl tin, and dibutyl
butoxy chlorotin, and mixtures thereof.
22. The method according to claim 16, further comprising an
anti-corrosion agent.
Description
RELATED APPLICATION
[0001] This application claims priority to Provisional Application
No. 60/461,800 filed Apr. 10, 2003, the disclosure of which is
hereby incorporated by reference in its entirety.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention relates to a thermal barrier
composition for use on a variety of substrates that are exposed to
high temperatures. Exemplary substrates include pipelines, engine
parts including jet engine components, water conduits including
tubes in power plants, reactor vessels and exhaust manifolds.
[0003] Substrates, particularly metal substrates, can be subjected
to high temperatures causing fatigue, cracking, distortion and the
like of the substrate. For example, components of a jet engine or
the surrounding parts of the jet can be exposed to temperatures in
excess of 1800.degree. F. In such a situation, it is readily
apparent that fatiguing or cracking can lead to catastrophic
failure. Similarly, piping used in various manufacturing facilities
can be subjected to temperatures in excess of 400.degree. F. caused
by the liquid or gas passing through the pipe. In such an
application, it is preferred that the coating not only provide a
thermal barrier but also provide anti-corrosion properties.
SUMMARY OF THE INVENTION
[0004] The thermal barrier composition of the present invention
comprises a glassy matrix comprising an alkoxy-functionalized
siloxane and a functionally-terminated silane or siloxane,
polymethylsilsesquioxane dissolved in a crosslinking agent, and
optionally a filler and/or hollow glass microspheres. The glass
matrix provides good adhesion to the surface being coated, as well
as, toughness, crack resistance, durability, abrasion resistance,
heat resistance and stability in the particular environment.
DETAILED DESCRIPTION OF THE INVENTION
[0005] As briefly discussed above, the present invention relates to
a thermal barrier composition. The thermal barrier compositions
comprises a glassy matrix comprising an alkoxy- functionalized
siloxane and a functionally-terminated silane or siloxane,
polymethylsilsesquioxane dissolved in a crosslinking agent, and
optionally a filler and/or hollow glass microspheres. The thermal
barrier composition of the present invention can be coated onto a
wide variety of substrates including steel, stainless steel,
titanium, aluminum, magnesium and zinc. The coating can withstand
continuous use temperatures of 1800.degree. F. or higher. Moreover,
the composition is resistant to corrosive agents such as nitrogen
and sulfur compounds.
[0006] Suitable alkoxy-functionalized siloxanes include
polydiethoxysiloxane, tetraethoxysiloxane, tetramethoxysiloxane,
and polydimethoxysiloxane. A preferred alkoxy-functionalized
siloxane is polydiethoxysilane. Suitable functionally-terminated
silanes or siloxanes include silanol-terminated, vinyl-terminated
and amino-terminated silanes or siloxanes such as
epoxy-functionalized polydimethylsiloxane, aminopropyltriethoxy
silane and silanol-termainated siloxane.
[0007] The glassy matrix is crosslinked using a titanium or tin
catalyst. Suitable catalysts include titanium alkoxides such as
titanium methoxide, titanium ethoxide, titanium isopropoxide,
titanium propoxide, titanium butoxide, titanium diisopropoxide (bis
2,4-pentanedionate), titanium diisopropoxide bis(ethylacetoacetao)
titanium ethylhexoxide, and organic tin compounds such as dibutyl
tin diacetate, dibutyltin laurate, dimethyl tin dineodecanoate,
dioctyl dilauryl tin, and dibutyl butoxy chlorotin, as well as
mixtures thereof. The glassy matrix can be formed by using a
Sol-Gel process such as described in U.S. Pat. No. 6,313,193, the
disclosure of which is incorporated herein by reference in its
entirety. Other methods of forming the matrix will be within the
skill of one in the art.
[0008] The polymethylsilsesquioxane ("POSS") is dissolved in a
crosslinking agent preferably titanium isopropoxide. By dissolving
in titanium propoxide, up to about 40 percent of the POSS can be
dissolved as compared to about 10 percent or less solubility in
solvents. In operation, the glassy matrix and the
polymethylsilsesquioxane are crosslinked or catalyzed separately so
as to avoid premature gelation of the product prior to use.
[0009] The thermal barrier composition may also optionally include
fillers such as, without limitation, glass fibers, fumed silica,
mica, kaolin, bentonite, talc, zinc oxides, iron oxides and
pigments or other fillers, as will be readily apparent to those
skilled in the art. The composition may also include hollow glass
microspheres to provide additional heat resistance. Preferably,
thin-walled glass microspheres are used. Typically the volume
percent of glass microspheres is from about 30 percent to about 80
percent. If the higher amount is used, it is preferable to include
milled glass fibers to improve durability. Anti-corrosion agents
such as zinc phosphates and zinc salts can also be added.
[0010] In operation, the thermal barrier composition of the present
invention can be applied to a substrate by roll-coating, brush,
spray coating dipping and the like. It is preferred that the user
mix the catalyst with the other components right before or
substantially contemporaneously with application to form an
interpenetrating polymer network of glass and silicone on the
surface of the substrate. Inasmuch as crosslinking occurs via a
moisture condensation reaction between ethoxy and hydroxyl groups,
the condensation inherently present on the substrate and/or in the
atmosphere can be used advantageously.
[0011] The following specific examples are provided to afford a
better understanding of the present invention to those skilled in
the art. It is to be understood that these examples are intended to
be illustrative only and is not intended to limit the invention in
any way.
EXAMPLES
Example 1
[0012] 1. Formulation
1 wt % Component 6.79 Poly(methylsilsesquioxane) 10.50 Titanium
isopropoxide 4.19 Polydiethoxysiloxane 21.00 Silanol-terminated
polydimethylsiloxane (4200 g/mol) 7.35 Titanium diisopropoxide
(Bis-2,4-pentanedionate) 4.19 Polydiethoxysiloxane 31.49 Mica 325
mesh 13.48 Heucophos ZPO (zinc organophosphate) Corrosion
Protection 1.50 Heucorin RZ (zinc salt) Corrosion Protection
[0013] 2. Manufacturing Steps
[0014] The first step is to dissolve the polymethysilsesquioxane
(POSS) into the titanium isopropoxide (TIPO). This is accomplished
by mixing the POSS into the titanium isopropoxide and heating at
100.degree. C. for 24 hours.
[0015] The second step is to terminate the silanol groups on the
ends of the polydimethylsiloxane. This is accomplished by mixing
the silanol terminated polydimethylsiloxane with the titanium
diisopropoxide (bis-2,4-pentanedionate) and allowing the mixture to
crosslink for 1 hour. If this step is not performed, the silanol
groups on the polymer will instantly react with the titanium
isopropoxide and the system will gel in a matter of seconds.
[0016] The third step is to add the remaining components to the
POSS/TIPO (A component) keeping the titanium diisopropoxide
(bis-2,4-pentanedionate- )/polydimethylsiloxane mixture out as the
B component in an A/B system.
Example 2
[0017] Formulation
2 wt % Component 24.07 Polysilsesquioxane dissolved in titanium
isopropoxide and 20% polydiethoxysiloxane 5.42 Epoxy-functionalized
polydimethylsiloxane 0.61 Aminopropyltriethoxy silane 16.05 Milled
glass fiber 10.57 Hollow glass microspheres 1.20 Dibutyl tin
dilaurate 40.12 Isopropyl alcohol 1.78 Titanium dioxide 0.18 Carbon
Black
[0018] The formulation was manufactured using the same steps as
Example 1 except that the POSS did not have to be pre-reacted with
the TIPO. The formulation of Example 2 was used in various tests as
described below and in Table 1.
3TABLE 1 Property Approach Test Method Standard Results Flexure
Mechanically flex a coated titanium Apply coating to 6-inch
titanium ASTM- 6 of 10 strips experienced cracking strip until the
coating cracks or strips. Bend strips over rods of D6272 when bent
over 1.50" rods. Only 4 delaminates increasing diameter until
cracks modified of 10 strips experienced cracking appear. when bent
over 1.25" rods. Conclusion: excellent flexure for intended
application Lap Joint Test adhesion of coating to jet engine Apply
coating to Ti strips ASTM Coating became stronger after Adhesion
parts. (1" .times. 6" .times. 1/8"). D3164.03 exposure to high
temperature. Bond them. Strong adhesion to Ti - no observable
degradation from high temperature. All failures were cohesive. 1.
R-Value 1. Determine R-value from independent 1. Measure thermal
conductivity 1. ASTM Thermal conductivity = 2. Temperature lab for
3 thicknesses (1/8-inch, 1/4-inch, at 700.degree. F. of samples of
varying E1530-99 0.15 W/m * K at 561.degree. F. difference =
200.degree. F. and 1/2-inch). Estimate temperature thickness with
independent lab. 2. Turkey Temperature Delta across coating = drop
using AFRL models. 2. One side of coating held at Fryer Rig.
337.degree. F. with 3.0 mm thick coating. 2. Demonstrate coating
will create 200.degree. F. 1000.degree. F. Temperature measured at
temperature delta. TBC-Ti interface. Durability Perform in-house
tests tailored to the a. Simulate 200-lb person standing ASTM High
probability that coating will operational environment during Phase
I, on a coasted plate and pivoting. D5420-98a have sufficient
durability. to determine feasibility. b. Drop tool on coated plate
form ASTM 4-feet. D968-93 c. Perform simple abrasion resistance
test using falling sand method. Repairability Intentionally damage
coated Ti coupons None Repair tests demonstrated that (hammer,
scrape). Repair the coupon coating was restored to like-new and
assess the quality of the repair by condition. knife adhesion tests
and visual inspection. Vibration Use AFRL table vibration that will
AFRL AFRL Results indicate high probability provide 160 dB noise
and 900.degree. F. that coating will withstand Quartz lamp.
vibration environment.
[0019] Durability Testing
[0020] A series of durability tests were performed on the coating
composition of Example 2. These tests were designed to simulate
real-world events that will test the durability of the coating. The
three specific tests performed on the coating composition of
Example 2 included: two tool drop tests, a falling sand test, and a
200 lb, 90.degree. pivot test.
[0021] The first tool drop test consisted of dropping a 106 gram
wrench from a height of 48 inches onto a panel coated with the
coating composition of Example 2. This test which was repeated
multiple times resulted in a dent of about 5 mm.times.5 mm. The
second tool drop test consisted of dropping a 783 gram hammer from
the same 48 inch height. The tool drop resulted in a dent of about
15 mm.times.25 mm.
[0022] The indentions from the tool drop tests are consistent with
the energy expected form objects of similar size and mass dropped
form a height of 48 inches. No cracking or delamination occurred
the coating and the divots can be easily repaired with the coating
composition of Example 2.
[0023] The falling sand test consisted of dropping 1 gallon of sand
from a height of 1.5 feet in a concentrated stream onto the surface
of a steel panel coasted with the coating composition of Example 2
mounted 45.degree. to the falling sand.
[0024] As a results of this test, the impact zone was abraded in a
region about 10 mm.times.16 mm.times.0.5 mm. The coating
composition of Example 2 demonstrated good abrasion resistance.
[0025] The third durability test consisted of a 200 lb person
standing on a plate coated with the coating composition of Example
2 with all weight on one foot. Then the person pivoted 90.degree..
No damage resulted to the coating composition of Example 2. The
test demonstrates the coating composition of Example 2 can be
walked on (e.g., a plane wing) with no damage.
[0026] Temperature Delta Data
[0027] A titanium plate with a 2.5 mm build of the coating
composition of Example 2 was prepared. A 3 mm wide channel was cut
into the coating from the center of the plate to the edge, and a
thermocouple was positioned in the channel such that it would be in
contact with the titanium plate. The coating composition of Example
2 was applied over the thermocouple to fill the channel and seal
the thermocouple at the interface of the coating composition of
Example 2 and the titanium plate, producing a sample with the
thermocouple counted at the interface of the coating composition of
Example 2 and the titanium. Total coating thickness was
approximately 3.0 mm.
[0028] After the coating was cured, the plate was placed onto a
steel block and was heated to a temperature of 1057.degree. F. by a
burner on the turkey fryer. The sample was placed with the coating
composition of Example 2 directly in contact with the hot steel
block, and allowed to equilibrate for 78 minutes to allow for
steady state heat flow.
[0029] The temperature measurement at the coating composition of
Example 2-titanium interface was found to be 720.degree. F. with
the hot steel measuring 1057.degree. F.: a temperature delta of
337.degree. F. across the coating composition of Example 2 for a
coating that is 3.0 mm thick.
[0030] Measure Thermal Conductivity
[0031] Thermal conductivity was measured on a free standing coating
composition of Example 2 film using the ASTM E1530 standard test
method. Measurements were conducted at 105.degree. F., 334.degree.
F., and 561.degree. F. The results are listed in the Table 2.
4TABLE 2 Thermal Conductivity Test (ASTM D1530) Measurement Thermal
Conductivity Temperature .degree. F. (W/(m * K)) 105.4 0.11 334.2
0.12 560.8 0.15
[0032] In the specification and examples, there have been disclosed
typical preferred embodiments of the invention and, although
specific terms are employed, they are used in a generic and
descriptive sense only and not for purposes of limitation of the
scope of the invention set forth in the following claims.
* * * * *