CA2023379A1 - Coating for protecting a carbon-carbon composite for oxidative degradation - Google Patents
Coating for protecting a carbon-carbon composite for oxidative degradationInfo
- Publication number
- CA2023379A1 CA2023379A1 CA002023379A CA2023379A CA2023379A1 CA 2023379 A1 CA2023379 A1 CA 2023379A1 CA 002023379 A CA002023379 A CA 002023379A CA 2023379 A CA2023379 A CA 2023379A CA 2023379 A1 CA2023379 A1 CA 2023379A1
- Authority
- CA
- Canada
- Prior art keywords
- carbon
- composite
- range
- black glass
- carbon composite
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/85—Coating or impregnation with inorganic materials
- C04B41/86—Glazes; Cold glazes
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C14/00—Glass compositions containing a non-glass component, e.g. compositions containing fibres, filaments, whiskers, platelets, or the like, dispersed in a glass matrix
- C03C14/004—Glass compositions containing a non-glass component, e.g. compositions containing fibres, filaments, whiskers, platelets, or the like, dispersed in a glass matrix the non-glass component being in the form of particles or flakes
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/4505—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application
- C04B41/455—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application the coating or impregnating process including a chemical conversion or reaction
- C04B41/4554—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application the coating or impregnating process including a chemical conversion or reaction the coating or impregnating material being an organic or organo-metallic precursor of an inorganic material
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
- C04B41/5022—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with vitreous materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
- C09D183/04—Polysiloxanes
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2214/00—Nature of the non-vitreous component
- C03C2214/04—Particles; Flakes
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Dispersion Chemistry (AREA)
- Geochemistry & Mineralogy (AREA)
- General Chemical & Material Sciences (AREA)
- Wood Science & Technology (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Paints Or Removers (AREA)
Abstract
ABSTRACT OF THE INVENTION
A process for forming a high temperature oxidation resistant coating on a carbon-carbon composite is disclosed and claimed. The process comprises applying a cyclosiloxane monomer blend containing a filler such as silicon carbide to a carbon-carbon composite, polymerizing and pyrolyzing said blend to form a filled black glass protective coating on the carbon-carbon composite.
A process for forming a high temperature oxidation resistant coating on a carbon-carbon composite is disclosed and claimed. The process comprises applying a cyclosiloxane monomer blend containing a filler such as silicon carbide to a carbon-carbon composite, polymerizing and pyrolyzing said blend to form a filled black glass protective coating on the carbon-carbon composite.
Description
A COATING FOR PROT~CTINC A CAR13ON-CAIIBON COMPOSITR
FaOM OXIDATIVE DEGRAI)ATION
BACElGROUNI) OF TUE IN~fENTION
............... . .. . . .. ........ . ... .
Carbon-carbon composites are us~u] materials for high temperature applications. Characteristics such as high heat of ablation, thermal shock resistallce, str~ngth improvement at elevated temperatures, and chemical inertness result in a mat~rial that is capable of high performance in e~treme thermal environments. Carbon-carbon composites consist of a fibrous carbc-n subslrate in a oarbonaceous matrix wherein each .onstitueot may range from carbon to graph:ite. The temperature capabilities of these cc~mpositt-~s extend to over 6000OF and the strength of the composit~s is about twenty times thHt of graphite, yet they are lighter and have a density of les~ than 1.8 grams per cubic centimeter. Sislce carbon-carbon composites o~idize in air at te.mE7eratures above 400~, such composites require a co~tin~ to protect l:hem from ~xidation.
A typical c:arbon-carbon composite is formed from graphite cloth, impregnated with a carbo~aceous polymer or resin, which is laid in a form or mold and cured. After trimming, the maleri~l is pyrolyYefl to convert the polymer or re~in to graphit~. The soft composite is reimpregnated and repyroly7.ed as many times as is necessary to form the composite of correct strength and density. Ttle composite can be us~d as is or can be coated to pro~ect it from severe cond.ition~ of use.
One coating te~hnique disclosed in U.S. Patent 4,321,298 involves t`oating ~ fibrous carbc)n materi~ll containing boron with a flexible thermosetting resin which contains a refractory metal such as tungsten or molybdenum. T~le advantage to this technique is that a metal boride is formed at high tsmperature~ which is mor~ stable than boron cnrbide. However, no ment.ion ;s madt? to applying thi technique to narbon-carbon composites without boron. In fact the invention is aime~
at preventing the detrimental interaction of boron and the ~arbon ~ib~rs.
Acl~itionally, U.S. Patent ~,~18,591 tea~he~. a method of preparing a si]ioon oarbide-carbon composite. The process involves using a polyoArbosilane to impregnste a base material. Patentee shc)ws no appreciation regarding the high temperature resi~tance to oxidation of these composites. Since the composite contains free carbon it would not be expeoted to be very stable at high temperatures.
In contrast to this prior art, the instant invention disclose~ a method of forming a high temperature oxidation resistant coating comprising a black glass on a carbon-carbon composite. ~his extends the usable temperature range ~or these carbon-carbon composites.
BRIEF DESCRIPTION OF THR INVENTION
As hereinbefore described, carbon-carbon composites are light, tough, ancl strong and are an ideal structural material for demanding performance. However, carbon-carbon composites nannot be used in air at: temperatures above about 400C since the carbon of ~he composite will oxidize.
One object of this invention is to form a coating on t:he ~arbon-oarbon nomposite which will protect the composite from high temperature oxidation.
A further object of this invention is to produce a conling conlaining a filler on a carhon-carbon compo~ite which will r~sist p~eLing and flaking from the surface of the composite.
One broad embodiment of this invention is a method of forming a high temperature oxidation resistant coating on n carbon-carbon oompoC~ite compri.si.ng the ~teps of:
. a) apply:ing a blend of a hydro~ilylation catalyst and l? a oyclosiloxane monomer of formula : .
,: ;: . . . . , . . ~ -- .
where n is an integer from 3 tv about 20, R is hydrogen, and R' is an alkene having from 2 to about 20 carbon atoms and containing a vinyl-silicon bond, or 2) at least two different cyclosiloxane monomers of the same formula as above and with the same n integer valuc range where R' is an alkyl group of from 1 to about 20 carbon atoms, and in one cyclosiloxane monomer R is hydrogen and in ~he others R is an alkene of from to about 20 carbon atoms containing a vinyl-~ilicon bond to a carbon-cart70n composite to afford a coatecl carbon-carbon composite:
(b) curing said coated carhon-carbon composite at curing condition~ to produce a cyclosiloxane polymer coatecl carbon-carbon composite;
(c) pyrolyzing said polymer coatetl carbon-carbon composite at pyrolyzing conditions to produce a black glass coating on said c~lrbon-carbon composite; and -.
(d) recov~ring saici black glass coated carbon--carbon ~ -composite.
A further l)road embodiment of th.is invention comprises a method of forming a high temperature oxidation resistant coating on a carbon-carbon compo~ite compriæing the steps:
a) polymer.izing a hlen(l of a hydrosilylation cataly~t, a filler and 1) a cyclosiloxane monomer of formula where n i5 ~n integer from 3 to about 20, R is hydrogen, and R' is an alkene h~ving from 2 to about 20 carbon atoms and containing a viDyl-silicon bond, or 2) at least two differ~nt cyc].osiloxane monomers o~ the ;~
same formula as ~bove and with the same n integer value range where ~' is an alkyl group oF ~rom l to ~bou~ 20 carbon ~ntoms, and in ono cyclosilo~anc monomer R is hydrogen and in the others R is an ~lkene o~
from to ~bout 20 carbc~n atoms containing ~ viny]-silicon bond to pro(iuoe a blaok glass precursor polymer oontaining a filler;
b) pyroly~ing said polymer precursor at pyroly7.ing conditions to ~orm a black glass powder containing a filler;
c) reducing the part.:icle siz~ of the filled black glass pow~er, d) mixing ~aid reduced parti<:le size black glass with a new portion of the blend of the cyclosiloxane monomers and hydrosilylation cataly-st and optionally a filler of step (a) to form a slurry.
e) applying said slurry from step (d) to a carbon-c~rbon composite;
f) curing said coat.ed carbon-carbon composite at curing conditions to produoe a filled cyclosiloxane polymer coated carbon--carbon composite;
g) pyrolyzing sai~ filled polymer coated carbon--carbc~n compos.ite at pyrolyzing condj.tions to produce a Eilled b].ack glass conta:ining coating on snid carbon-~:arbon composite; and h) recovetil1g said filled black glass coated carbon-carbon composite. Add:itionally, the blac1c glass coated carbon-carbon composi~
may be ln1pregnated witll the liquid mixture of step (a), and pyroly~ed io produce a crack-free filled bl~ck glass containing coating on saic1 carbon-carbon cvmposite.
Ot.her objects and embodiments will be found in the follc~wing further detailed descripl:ion of the present invention.
DETA.TLED DESCRIPTION OF T~E INV~NT.ION
.. This invention is concerned with forming a protectiva cnating on a c:arbvn--carbon composite to prevenl. oxidation o~ the comp~site at temperatures in exca~s of 400C. This coating is fo~ed on the carbon-carbon composit.e by applying a blend conLaining a cyc].osilvxd11a monomer and containing a hydrosilylation catalyst, curi.ng , . ~ ., . ; , .-, - . ~ - , . ., . - - : -- . ~ , . , - : ~ , . -- - ~ . , - . -the coated composite, pyroly~ing the coating to provide a bLack glass prot.eotive coating on th~ ~arbon-~arbon compo-it.e and rccoverin~ sai~i coated carbon-carbon composite. Additionally, a filler may be ~dded to said blend ~o improve the d-lrab:i.lity of th~ re~ultant coating. ~inor oracks in this (~oating are filled in by impregnation with the monomer blend followed by pyrvlysis of the new coating to give a macrocrack-free surface.
For the purposes o~ this application antl the appended claims, the following definition of terms will apply:
1) crack-free means that. th~ surface coating shows little or no macrocracks;
FaOM OXIDATIVE DEGRAI)ATION
BACElGROUNI) OF TUE IN~fENTION
............... . .. . . .. ........ . ... .
Carbon-carbon composites are us~u] materials for high temperature applications. Characteristics such as high heat of ablation, thermal shock resistallce, str~ngth improvement at elevated temperatures, and chemical inertness result in a mat~rial that is capable of high performance in e~treme thermal environments. Carbon-carbon composites consist of a fibrous carbc-n subslrate in a oarbonaceous matrix wherein each .onstitueot may range from carbon to graph:ite. The temperature capabilities of these cc~mpositt-~s extend to over 6000OF and the strength of the composit~s is about twenty times thHt of graphite, yet they are lighter and have a density of les~ than 1.8 grams per cubic centimeter. Sislce carbon-carbon composites o~idize in air at te.mE7eratures above 400~, such composites require a co~tin~ to protect l:hem from ~xidation.
A typical c:arbon-carbon composite is formed from graphite cloth, impregnated with a carbo~aceous polymer or resin, which is laid in a form or mold and cured. After trimming, the maleri~l is pyrolyYefl to convert the polymer or re~in to graphit~. The soft composite is reimpregnated and repyroly7.ed as many times as is necessary to form the composite of correct strength and density. Ttle composite can be us~d as is or can be coated to pro~ect it from severe cond.ition~ of use.
One coating te~hnique disclosed in U.S. Patent 4,321,298 involves t`oating ~ fibrous carbc)n materi~ll containing boron with a flexible thermosetting resin which contains a refractory metal such as tungsten or molybdenum. T~le advantage to this technique is that a metal boride is formed at high tsmperature~ which is mor~ stable than boron cnrbide. However, no ment.ion ;s madt? to applying thi technique to narbon-carbon composites without boron. In fact the invention is aime~
at preventing the detrimental interaction of boron and the ~arbon ~ib~rs.
Acl~itionally, U.S. Patent ~,~18,591 tea~he~. a method of preparing a si]ioon oarbide-carbon composite. The process involves using a polyoArbosilane to impregnste a base material. Patentee shc)ws no appreciation regarding the high temperature resi~tance to oxidation of these composites. Since the composite contains free carbon it would not be expeoted to be very stable at high temperatures.
In contrast to this prior art, the instant invention disclose~ a method of forming a high temperature oxidation resistant coating comprising a black glass on a carbon-carbon composite. ~his extends the usable temperature range ~or these carbon-carbon composites.
BRIEF DESCRIPTION OF THR INVENTION
As hereinbefore described, carbon-carbon composites are light, tough, ancl strong and are an ideal structural material for demanding performance. However, carbon-carbon composites nannot be used in air at: temperatures above about 400C since the carbon of ~he composite will oxidize.
One object of this invention is to form a coating on t:he ~arbon-oarbon nomposite which will protect the composite from high temperature oxidation.
A further object of this invention is to produce a conling conlaining a filler on a carhon-carbon compo~ite which will r~sist p~eLing and flaking from the surface of the composite.
One broad embodiment of this invention is a method of forming a high temperature oxidation resistant coating on n carbon-carbon oompoC~ite compri.si.ng the ~teps of:
. a) apply:ing a blend of a hydro~ilylation catalyst and l? a oyclosiloxane monomer of formula : .
,: ;: . . . . , . . ~ -- .
where n is an integer from 3 tv about 20, R is hydrogen, and R' is an alkene having from 2 to about 20 carbon atoms and containing a vinyl-silicon bond, or 2) at least two different cyclosiloxane monomers of the same formula as above and with the same n integer valuc range where R' is an alkyl group of from 1 to about 20 carbon atoms, and in one cyclosiloxane monomer R is hydrogen and in ~he others R is an alkene of from to about 20 carbon atoms containing a vinyl-~ilicon bond to a carbon-cart70n composite to afford a coatecl carbon-carbon composite:
(b) curing said coated carhon-carbon composite at curing condition~ to produce a cyclosiloxane polymer coatecl carbon-carbon composite;
(c) pyrolyzing said polymer coatetl carbon-carbon composite at pyrolyzing conditions to produce a black glass coating on said c~lrbon-carbon composite; and -.
(d) recov~ring saici black glass coated carbon--carbon ~ -composite.
A further l)road embodiment of th.is invention comprises a method of forming a high temperature oxidation resistant coating on a carbon-carbon compo~ite compriæing the steps:
a) polymer.izing a hlen(l of a hydrosilylation cataly~t, a filler and 1) a cyclosiloxane monomer of formula where n i5 ~n integer from 3 to about 20, R is hydrogen, and R' is an alkene h~ving from 2 to about 20 carbon atoms and containing a viDyl-silicon bond, or 2) at least two differ~nt cyc].osiloxane monomers o~ the ;~
same formula as ~bove and with the same n integer value range where ~' is an alkyl group oF ~rom l to ~bou~ 20 carbon ~ntoms, and in ono cyclosilo~anc monomer R is hydrogen and in the others R is an ~lkene o~
from to ~bout 20 carbc~n atoms containing ~ viny]-silicon bond to pro(iuoe a blaok glass precursor polymer oontaining a filler;
b) pyroly~ing said polymer precursor at pyroly7.ing conditions to ~orm a black glass powder containing a filler;
c) reducing the part.:icle siz~ of the filled black glass pow~er, d) mixing ~aid reduced parti<:le size black glass with a new portion of the blend of the cyclosiloxane monomers and hydrosilylation cataly-st and optionally a filler of step (a) to form a slurry.
e) applying said slurry from step (d) to a carbon-c~rbon composite;
f) curing said coat.ed carbon-carbon composite at curing conditions to produoe a filled cyclosiloxane polymer coated carbon--carbon composite;
g) pyrolyzing sai~ filled polymer coated carbon--carbc~n compos.ite at pyrolyzing condj.tions to produce a Eilled b].ack glass conta:ining coating on snid carbon-~:arbon composite; and h) recovetil1g said filled black glass coated carbon-carbon composite. Add:itionally, the blac1c glass coated carbon-carbon composi~
may be ln1pregnated witll the liquid mixture of step (a), and pyroly~ed io produce a crack-free filled bl~ck glass containing coating on saic1 carbon-carbon cvmposite.
Ot.her objects and embodiments will be found in the follc~wing further detailed descripl:ion of the present invention.
DETA.TLED DESCRIPTION OF T~E INV~NT.ION
.. This invention is concerned with forming a protectiva cnating on a c:arbvn--carbon composite to prevenl. oxidation o~ the comp~site at temperatures in exca~s of 400C. This coating is fo~ed on the carbon-carbon composit.e by applying a blend conLaining a cyc].osilvxd11a monomer and containing a hydrosilylation catalyst, curi.ng , . ~ ., . ; , .-, - . ~ - , . ., . - - : -- . ~ , . , - : ~ , . -- - ~ . , - . -the coated composite, pyroly~ing the coating to provide a bLack glass prot.eotive coating on th~ ~arbon-~arbon compo-it.e and rccoverin~ sai~i coated carbon-carbon composite. Additionally, a filler may be ~dded to said blend ~o improve the d-lrab:i.lity of th~ re~ultant coating. ~inor oracks in this (~oating are filled in by impregnation with the monomer blend followed by pyrvlysis of the new coating to give a macrocrack-free surface.
For the purposes o~ this application antl the appended claims, the following definition of terms will apply:
1) crack-free means that. th~ surface coating shows little or no macrocracks;
2) vinyl-silicon bond means that a carbon with a double bond in an alkene i~ bound directly to a silicon atom;
3) polymerizing means to make a polymer in a flowable ~tate from the cyclosiloxane monomers;
4) curing refer~ to the polymerization o~ a cyclosiloxane monomer to the point that a three-dimensional or a cros.~-lirlked polymer is formed and the resultant polymer no longer flows; and 6. a black glass is defined by the empirical formula SiCxOy where x ranges from 0.5 to about 2.0 and y ranges from 0.5 to about 3Ø
A typical coating is obtained by dipping a carhon-carboll composite into a mixture of a hydros.ilylation .atalyst, a c:yclosiloxane monomer having a vinyl silicon bond, and a cyclosiloxane monomer havi.ng a hydrogen--silicnn bond, polymerizin~ and curing this coating, and t.hen pyrolyzing th~ cured coating to produce a hard black glass coating on the carbon-carbon compoæite. In a modification of the above process, the monomeric cyclosiloxane may contain botll vinyl silicon and hydrogen-s.ilicon bonds in 8 single monomer molecule. In addition, thc durability of this coating of black glass may be increased hy utilizing a monomeric mixture containing a filler such as a dispersed sil.icon carb:ide-powder to produc~ a filled black glass coating. If ~o desired, the monomeric b]end coDtaining no f:iller may be used to apply a prot.ective coating to the carbon-carbon composite.
C~closiloxanes are the preferred silicon containing compuunds for forming a coating over the carbon-carbon composites.
.- - , ....... . : -. . : ~ -. : . . . . - - . . :
. : . , :: . . . . .-. , - , . .
E~amplec oF cyclosilo.Yanes include, but are not limited to, 1,~,;,7-tetr~lmethylLetrahydrocyclotet.rasiloxane, 1,3,5,7-tetravinyltetrahydrocyclotetrasiloxane, L,3,~,7-tetravinyltetraethyk:yclotetrasiloxane, 1,3,5,7-tetravinyltetramethylcyclotetrasilo~ane, I,3,5-trimethyltrivinylcyclotrisiloxane, 1,3,~-trivinyltrihydrocyclotrisilo.Yane, 1,3,5-trimethyltrihy~lrocyclotrisiloxane, 1,3,5,7,9-pentavinylpentahydrocyclopent~ciloxane, l,3,~;,7,~-pentavinylpentamethylc:yclopentasilt)xane, 1,1,3,3,5,5,7,7-octavinylcyolotetrasiloxane, 1,1,3,3,ri,6,7,7-octahydrocyclotetrasiloxane, 1,3,5,7,9,11-hexavinylhe~methylcyclohexasiloxane, 1,3,~,7,9,11-hexamethylhexahydrocyclohexssiloxane, 1,3,5,7,9,11,13,15,17,19-decavinyldecahydrocyclodecasiloxane, 1,3,~,7,9,11,13,15,17,19,21,23,25,27,29-pentadecavinyl-pentadecahydrocyclopentadecasiloxane, 1,~,5,7-tetrapropenyltetrahydroc:yclotetrasiloxane, 1,3,5,7-tetrapentenyltetrapentylcyclotetra~iloxane and 1,3,5,7,9-pentadecenylpentapropylcyclopenta~iloxane.
The polymerization reaction is carried out in the presen-:~
of ~I hydrosi]ylation catalyst. The hydrosilYIation oatalyst can be chosen ~rom those catalysts that are well known in the art. Well known catalysts are, for example, nickel carbonyl, iron carbonyl, c:obalL
carbooyl, mangane~e carbollyl, the platinum catalysts (metallic platinum or platinum com~ounds) and the rhodium catalysts. Of the~e catalysts, the ~latinum cataly~ts are particuldrly preferred. The platinum compound~ that. are catalytically active for polymerizing a cyclosiloxanc include but are not limited to chloroplatinic acid, platinum divinyltetramethyldisiloxane, platinum carbonyl dichloride, alld l:ris~triE)henylph~)~phine)platinum. The catalyst cdn be added either in a he~erogeneous or homogeneous phase, although not Wit}l eqlliValent results. A homogeneous catalyst js preferred. The catalyst is present in amount3 r~nging rrom about 1 pE~m to aboul 700 ppm of the metal in th~
monomeric blend.
-Application o~ the cyclosilo~ane monomer plushydroxilylation cat~lyst blend to the oarhcln-carbon composite can be ~fected by any method known in the art. These methods include dipping the compo~ite into the blend, spraying the blencl onto the composite or brushing the blend onto the composite. These methods of application can be used for any of the blends describetl herein.
Although application of any of the blends described in this invention can be done at atmospheric pressures, it is preferre~ to apply the desired blend to the carbon-carbon composite at reduced pressures.
Reduced pressures in the range of about 1 mm ~Ig to about 29 mm Hg are preferred for the applieation step. The advantage to using reduced pressures during the application step is that considerably fewer macro-cracks are produced after pyrolysis of the coating. The time required to effect the applioation can range from about 1 minute to about 60 minutes.
The curing aml polymerization tako place at a temperature range of from about 25C to about 300C. The amount of time required to effec:t the polymerization and curing ranges ~rom about one minute to about 600 minute~ with the longer a~olmts of time required at the lower temperaturcs. Curing is effected by simply e~tending the amount of time at the desired temperature. While the polymerizing and curing st~ps of this invention can be performed at atmospheric pressure, a hetter product is formed if the polymerization and ouring steps are done und~r pressure. ~y doing the polymeri~ation and curing steps under pressure, nucleated bubbling is prevented which would otherwise leave cracks and voids in the poly~er coatin. Pressures in the range from about l~ psi to about 30,000 p8i can be used to prevent nucleated bubbling.
The pyrolysis step of this invention coDsists of heatin the polymer coated composite in a non-oxidizing gas atmosphere to a te~E~erature in the range of from about 700C to ~bout l400C for a time in the ran~e of ~rom about 1 hour to about 300 hours, and at a pressure in th~ range of from about 14 psi to about 30,000 psi to form the black gl~ss coating of the instant invention. Rxamples of non-oxidiæing gases include but are not limited to nitrogen and argon.
~.
- ~ : . : - . ............................ . . --: . .
, : ' ~ -. - ~ , . -It is contemplated as within the scope of this invention to repe~ the above steps to build up a layered coating on the carbon-carbon compos.ite. The protect.ive coating can be build-up by so ~hat it mak~?s up no more than 5 per~ent of the total weight of the composite.
Additionally, by applying thc coating in multiple layers, any macro cracks which are formed during the pyrolysis of the first layer are filled in by fresh blend <lurin~ ~pplication of a subse~uent layer and are thus eliminated. Thus, a macrocrack-free protective coating is formed by applying the coating in several layers.
While the cyclosiloxane monomeric blend can be used by it..self to ~orm a coating on the carbon-carbon composite, it is pre~`erabl.e to add a filler to the cyclosiloxane monomeric blend in order to impro~e thc durabi.lity of the resultant coating formed on the carhc~n--carbon composite. The fi.].ler may be dispersed in the monomeric cyelosilc~xane blend by my dis~rsion method ~nown in the art including but not limited to ultrasonic dispersion. This filler containing blend may be used to ~orm a coiatin~ over the carbon-carbon composite Qg described above.
Alternatively, the Eiller contnining monomeric c~c:losiloxane blend can be polymeri~ed and pyrolyze~ to form a black glass powder wh;ch contains a filler (hereinafter filled black glass). This met.h()(~ -resu].ts icl an even di.stribution of the ~iller in the black g].a~s. The particle si~c of t.h:is blacls glass powder containin~ filler cac be redu~ed to an average particle ~iameter of about .~ to about 10 microns.
Any c~c~nventional s.i~e reduction methods such as ball milling or Jet milling may be u~ed. This finely ground powder oan be dispersed in a fresh cyclosilox~ne monomeric b]cnd to give a slurry. This slurry c~
be applied to a c~rbon-carbon composite to form a protective coating wit.h improved durability and adherence versus ~ coating that does not contain a filled black g1ass.
ExamE>les of ~illers include, but Are not limited to, si:Lic~on carbide, silicon nitride, titania, hafnia, ~irconia, silica, alumirla and ~`
mixt.ures thereof. These filler~ can be present in the form of pow~lers, whiskers or fibers. The best results are achieved when the filler is pow~lerecl silicon carhi~e which is ~isperse~ in a cyclosiloxane monomeric . .
hlend by such means as ultrasonio dispersal, and which forms a black glass containing from c~out ~0O to about 70O~ by weight silicon carbide.
This ~illed black glass powcler is milled to gjve particles with an averclge particle diamet~r of about 7 microns ancl clispersecl in a ~resh batch of cyclosilo~ane monomer blend to form a slurry which is used to co~lt a composite and pyroly~ed to ~ive a filled black glass co~lting containing from about 1~% to about 65% by weig-ht silicon carbide and from about 86X to about 35% by weight black glass on the carbon-carbon composite. A lesser quality coating is achie~ed when the silicon carbide is directly dispersed in the monomeric: cyclosilo~aoe bl~-nd ancl then applied to the composite. It is also contemp]ated as within ths scope of this invention to clisperse the filled black glas3 in a cyclosiloxane monomeric blend containing a filler as well as a cyclosiloxane monomeric blend containing no filler. The Eiller, if any, used in the monomeric blend, in which the filled black glass is ~ispersed, may be diIferent from or identical to the filler used in the bla~k glass and can be pre~ent in the monomeric blend in a range of from about 20 to about 70~.
The followin~ examples are given for illustrative purpose~
onl~. It is to be understood that thess e~amples are not intended as an undue limitation on the broad scope of the invention a_ set forth in the appended claims.
EXAMPLR T
A monomeric s;loxane blend w~s produced by blendin~ i.2 grams of methylhydrocyclosiloxane whioh is a mixtur-e of cyclotrimer, cyclotetramer, cyclopentamer, and cyclohex~ner, with 10.0 gr~os of 1,3,~,7-tetraviayltetram~thyl-cyclotetraailoxane in the presence of 0Ø~ -ml of 3X platinumrdivinyltetramethyldisilo~ane complex in Yylene (this monomeric ~iloxane solution will be hereinafter referred to as solution A~. 14.3 grams of powclered silicon (arbiclc filler were ultrasonically dispersed in this blend followed by polymerization for 30 minutes at a temper~ture of 5~C to produce a polymer containing silicon carbide which was subsequently pyrolyzed in a nitrogen atlooqphere at a tleating . . , , rate o~ 200C per hour to 120nC to afford a black glass containing silicon carbide. The resultant black glass/silicon carbide was thcn reduced in size to an average particle diameter of about 7 microns by h~ll milling. The black g]ass/silicon carbide powder cont~inecl .~bout 50~ silicon carbide, as c~lculat~.d from the stoi.chiometry of th~
rcaction.
EXAMP~E II
.... . . ..
A monomeric cyclosiloxane blend identical to solution A was prepared and to this blend wa~ added the black glass/silicon carbide powder of ~xample I. The powder present in 50% by weight, was slurric-d .-into the monomeric cyclosilox~ne blend utilizing an ultrasonic dispersion melhod (solution ~). A carbon-carbon cnmposite waæ dipped into the slurry described above and the coated carbon-carbon composite was cured at. 60C ~nr about thirty minut.es to transform the reinforced monomeric mixture into a polymer coating on the composite. The polymer coat.ed composite wa~ then placed under flowi.ng nit.rogen in a 1200C
furnace for about 1 hour to produce a carbon-carbon composi.te coated with black glass cont.aining silic:on carbide.
In order to seal any cracks which may have developed durillg pyrolys:is of t.he coated composit.e, the black glass coated composite was place~ under vacuum and was impregnated with soluti.c)n A. Sub~e~uent pyrolysis produccd a hlack glass coating with fewer m~crocrac~s t.han found pri.or to i~pregnation. No macrocracks were induced by heat~ing the coatecl composit.e to 1~00C :in argon with subsequent slow cool.ing.
EXAMPLE III
,.. ............ _ A black glass cont.aining silicon c:arbide coated c~rbon-call)on composite weighing 7.42 grams was heated in a vertical furnace i.n air at. a rate of 200C per hour up to 9~0C. After eight hours at.
950C, the sampl.e was cooled to room temperature at a rate of 200C pe hour. The ~pecimen retained 75X of its weight after undergoing this oxiliation test. Observation of the thermograv;metric analysis thermogram indicated that the weight loss occllrred primarily during t.he -ramp to 950C at 200~C per hour. The ooating consi~;ted of 73o by weight black glass coating and 27~o by weight ~ilioon ~arbi(lc in the coating.
EXAMPLE r~
This ex~mple is included to describe the result when ~n unfilled black glass, made from a cyclosiloxane monomer, was slurried with a monomeric cyclosiloxane similar to the solution A blend prepared as in Example I. Thi~ unfilled black glass slurry was utilized in place of the silicon carbide fillecl blac:k glass slurr~.
An unfilled mixture made by ad~ing 7.2 gr~ms of methylhydrocyclosiloxane to lO.0 grams of l, 3, ~, 7-tetravinyltetra-methylcyclotetrasiloxane in the presence of 90 ppm platinum (the platinum is present in t,he s~me ~orm as in Example I) was polymerized at 55C Eor 80 minutes and subsequently pyrolyzed at 1200C under argon to provide an unfilled black glass. The black glass so produced was reduced to a powder by ball milling and then added to a new portion of the unfilled monomeric cyclosiloxane blend to produce a slurry which was applied to a carbon-carbon co~posite. Each item was infiltrated with Solution A. The infiltration step wns performed in one case at atmospheric pressure and in a second :ase under a vacuum of 29 mm of merc:ury. Each item was pyrolyzed at 1'~00C as in Exclmple I to giYC a ~' black glass coated oomposite. Each coated composite was then heated at l200C in air for about 3 hours and eac:h composite lost about, 80o of its initial weight thus showing that ]ess effective protection is afEorded hy black glags alone.
For c~omparlson, a eonte.d composit:e made using th~ procedure of Exampl~ II was heated in air at 1200C for about 3 hours and ~howed a weight 109s of 23% after the oxidntion test. An uncoated carbon-carbon composite was completely burned out in an identical test.
EXAMPLE V
This example is included in order to point out the difference in quality of the hlack glass coatin~ produced by ~: .
- . : ., -, . .
substituting pure silicon carbide for the black glass containing silicon carbide c-f Examp1e 1. To a new solution A prepared as in Ex~mple I was added ~OX silicon carbide powder to form a slurry. A carbon--arbon composite was coated with this slurry and the coat:ing was cured in a 60C oven for 60 minutes, and subsequently pyrolyzed under argon at 1200G ~or 1 hour. The coating cracked and flaked off. When silicon carbide whiskers were substituted for the silicon carbide powder, a better coating was produced, but neither coating was as good as that in Example II above.
- . , . . : .; :
A typical coating is obtained by dipping a carhon-carboll composite into a mixture of a hydros.ilylation .atalyst, a c:yclosiloxane monomer having a vinyl silicon bond, and a cyclosiloxane monomer havi.ng a hydrogen--silicnn bond, polymerizin~ and curing this coating, and t.hen pyrolyzing th~ cured coating to produce a hard black glass coating on the carbon-carbon compoæite. In a modification of the above process, the monomeric cyclosiloxane may contain botll vinyl silicon and hydrogen-s.ilicon bonds in 8 single monomer molecule. In addition, thc durability of this coating of black glass may be increased hy utilizing a monomeric mixture containing a filler such as a dispersed sil.icon carb:ide-powder to produc~ a filled black glass coating. If ~o desired, the monomeric b]end coDtaining no f:iller may be used to apply a prot.ective coating to the carbon-carbon composite.
C~closiloxanes are the preferred silicon containing compuunds for forming a coating over the carbon-carbon composites.
.- - , ....... . : -. . : ~ -. : . . . . - - . . :
. : . , :: . . . . .-. , - , . .
E~amplec oF cyclosilo.Yanes include, but are not limited to, 1,~,;,7-tetr~lmethylLetrahydrocyclotet.rasiloxane, 1,3,5,7-tetravinyltetrahydrocyclotetrasiloxane, L,3,~,7-tetravinyltetraethyk:yclotetrasiloxane, 1,3,5,7-tetravinyltetramethylcyclotetrasilo~ane, I,3,5-trimethyltrivinylcyclotrisiloxane, 1,3,~-trivinyltrihydrocyclotrisilo.Yane, 1,3,5-trimethyltrihy~lrocyclotrisiloxane, 1,3,5,7,9-pentavinylpentahydrocyclopent~ciloxane, l,3,~;,7,~-pentavinylpentamethylc:yclopentasilt)xane, 1,1,3,3,5,5,7,7-octavinylcyolotetrasiloxane, 1,1,3,3,ri,6,7,7-octahydrocyclotetrasiloxane, 1,3,5,7,9,11-hexavinylhe~methylcyclohexasiloxane, 1,3,~,7,9,11-hexamethylhexahydrocyclohexssiloxane, 1,3,5,7,9,11,13,15,17,19-decavinyldecahydrocyclodecasiloxane, 1,3,~,7,9,11,13,15,17,19,21,23,25,27,29-pentadecavinyl-pentadecahydrocyclopentadecasiloxane, 1,~,5,7-tetrapropenyltetrahydroc:yclotetrasiloxane, 1,3,5,7-tetrapentenyltetrapentylcyclotetra~iloxane and 1,3,5,7,9-pentadecenylpentapropylcyclopenta~iloxane.
The polymerization reaction is carried out in the presen-:~
of ~I hydrosi]ylation catalyst. The hydrosilYIation oatalyst can be chosen ~rom those catalysts that are well known in the art. Well known catalysts are, for example, nickel carbonyl, iron carbonyl, c:obalL
carbooyl, mangane~e carbollyl, the platinum catalysts (metallic platinum or platinum com~ounds) and the rhodium catalysts. Of the~e catalysts, the ~latinum cataly~ts are particuldrly preferred. The platinum compound~ that. are catalytically active for polymerizing a cyclosiloxanc include but are not limited to chloroplatinic acid, platinum divinyltetramethyldisiloxane, platinum carbonyl dichloride, alld l:ris~triE)henylph~)~phine)platinum. The catalyst cdn be added either in a he~erogeneous or homogeneous phase, although not Wit}l eqlliValent results. A homogeneous catalyst js preferred. The catalyst is present in amount3 r~nging rrom about 1 pE~m to aboul 700 ppm of the metal in th~
monomeric blend.
-Application o~ the cyclosilo~ane monomer plushydroxilylation cat~lyst blend to the oarhcln-carbon composite can be ~fected by any method known in the art. These methods include dipping the compo~ite into the blend, spraying the blencl onto the composite or brushing the blend onto the composite. These methods of application can be used for any of the blends describetl herein.
Although application of any of the blends described in this invention can be done at atmospheric pressures, it is preferre~ to apply the desired blend to the carbon-carbon composite at reduced pressures.
Reduced pressures in the range of about 1 mm ~Ig to about 29 mm Hg are preferred for the applieation step. The advantage to using reduced pressures during the application step is that considerably fewer macro-cracks are produced after pyrolysis of the coating. The time required to effect the applioation can range from about 1 minute to about 60 minutes.
The curing aml polymerization tako place at a temperature range of from about 25C to about 300C. The amount of time required to effec:t the polymerization and curing ranges ~rom about one minute to about 600 minute~ with the longer a~olmts of time required at the lower temperaturcs. Curing is effected by simply e~tending the amount of time at the desired temperature. While the polymerizing and curing st~ps of this invention can be performed at atmospheric pressure, a hetter product is formed if the polymerization and ouring steps are done und~r pressure. ~y doing the polymeri~ation and curing steps under pressure, nucleated bubbling is prevented which would otherwise leave cracks and voids in the poly~er coatin. Pressures in the range from about l~ psi to about 30,000 p8i can be used to prevent nucleated bubbling.
The pyrolysis step of this invention coDsists of heatin the polymer coated composite in a non-oxidizing gas atmosphere to a te~E~erature in the range of from about 700C to ~bout l400C for a time in the ran~e of ~rom about 1 hour to about 300 hours, and at a pressure in th~ range of from about 14 psi to about 30,000 psi to form the black gl~ss coating of the instant invention. Rxamples of non-oxidiæing gases include but are not limited to nitrogen and argon.
~.
- ~ : . : - . ............................ . . --: . .
, : ' ~ -. - ~ , . -It is contemplated as within the scope of this invention to repe~ the above steps to build up a layered coating on the carbon-carbon compos.ite. The protect.ive coating can be build-up by so ~hat it mak~?s up no more than 5 per~ent of the total weight of the composite.
Additionally, by applying thc coating in multiple layers, any macro cracks which are formed during the pyrolysis of the first layer are filled in by fresh blend <lurin~ ~pplication of a subse~uent layer and are thus eliminated. Thus, a macrocrack-free protective coating is formed by applying the coating in several layers.
While the cyclosiloxane monomeric blend can be used by it..self to ~orm a coating on the carbon-carbon composite, it is pre~`erabl.e to add a filler to the cyclosiloxane monomeric blend in order to impro~e thc durabi.lity of the resultant coating formed on the carhc~n--carbon composite. The fi.].ler may be dispersed in the monomeric cyelosilc~xane blend by my dis~rsion method ~nown in the art including but not limited to ultrasonic dispersion. This filler containing blend may be used to ~orm a coiatin~ over the carbon-carbon composite Qg described above.
Alternatively, the Eiller contnining monomeric c~c:losiloxane blend can be polymeri~ed and pyrolyze~ to form a black glass powder wh;ch contains a filler (hereinafter filled black glass). This met.h()(~ -resu].ts icl an even di.stribution of the ~iller in the black g].a~s. The particle si~c of t.h:is blacls glass powder containin~ filler cac be redu~ed to an average particle ~iameter of about .~ to about 10 microns.
Any c~c~nventional s.i~e reduction methods such as ball milling or Jet milling may be u~ed. This finely ground powder oan be dispersed in a fresh cyclosilox~ne monomeric b]cnd to give a slurry. This slurry c~
be applied to a c~rbon-carbon composite to form a protective coating wit.h improved durability and adherence versus ~ coating that does not contain a filled black g1ass.
ExamE>les of ~illers include, but Are not limited to, si:Lic~on carbide, silicon nitride, titania, hafnia, ~irconia, silica, alumirla and ~`
mixt.ures thereof. These filler~ can be present in the form of pow~lers, whiskers or fibers. The best results are achieved when the filler is pow~lerecl silicon carhi~e which is ~isperse~ in a cyclosiloxane monomeric . .
hlend by such means as ultrasonio dispersal, and which forms a black glass containing from c~out ~0O to about 70O~ by weight silicon carbide.
This ~illed black glass powcler is milled to gjve particles with an averclge particle diamet~r of about 7 microns ancl clispersecl in a ~resh batch of cyclosilo~ane monomer blend to form a slurry which is used to co~lt a composite and pyroly~ed to ~ive a filled black glass co~lting containing from about 1~% to about 65% by weig-ht silicon carbide and from about 86X to about 35% by weight black glass on the carbon-carbon composite. A lesser quality coating is achie~ed when the silicon carbide is directly dispersed in the monomeric: cyclosilo~aoe bl~-nd ancl then applied to the composite. It is also contemp]ated as within ths scope of this invention to clisperse the filled black glas3 in a cyclosiloxane monomeric blend containing a filler as well as a cyclosiloxane monomeric blend containing no filler. The Eiller, if any, used in the monomeric blend, in which the filled black glass is ~ispersed, may be diIferent from or identical to the filler used in the bla~k glass and can be pre~ent in the monomeric blend in a range of from about 20 to about 70~.
The followin~ examples are given for illustrative purpose~
onl~. It is to be understood that thess e~amples are not intended as an undue limitation on the broad scope of the invention a_ set forth in the appended claims.
EXAMPLR T
A monomeric s;loxane blend w~s produced by blendin~ i.2 grams of methylhydrocyclosiloxane whioh is a mixtur-e of cyclotrimer, cyclotetramer, cyclopentamer, and cyclohex~ner, with 10.0 gr~os of 1,3,~,7-tetraviayltetram~thyl-cyclotetraailoxane in the presence of 0Ø~ -ml of 3X platinumrdivinyltetramethyldisilo~ane complex in Yylene (this monomeric ~iloxane solution will be hereinafter referred to as solution A~. 14.3 grams of powclered silicon (arbiclc filler were ultrasonically dispersed in this blend followed by polymerization for 30 minutes at a temper~ture of 5~C to produce a polymer containing silicon carbide which was subsequently pyrolyzed in a nitrogen atlooqphere at a tleating . . , , rate o~ 200C per hour to 120nC to afford a black glass containing silicon carbide. The resultant black glass/silicon carbide was thcn reduced in size to an average particle diameter of about 7 microns by h~ll milling. The black g]ass/silicon carbide powder cont~inecl .~bout 50~ silicon carbide, as c~lculat~.d from the stoi.chiometry of th~
rcaction.
EXAMP~E II
.... . . ..
A monomeric cyclosiloxane blend identical to solution A was prepared and to this blend wa~ added the black glass/silicon carbide powder of ~xample I. The powder present in 50% by weight, was slurric-d .-into the monomeric cyclosilox~ne blend utilizing an ultrasonic dispersion melhod (solution ~). A carbon-carbon cnmposite waæ dipped into the slurry described above and the coated carbon-carbon composite was cured at. 60C ~nr about thirty minut.es to transform the reinforced monomeric mixture into a polymer coating on the composite. The polymer coat.ed composite wa~ then placed under flowi.ng nit.rogen in a 1200C
furnace for about 1 hour to produce a carbon-carbon composi.te coated with black glass cont.aining silic:on carbide.
In order to seal any cracks which may have developed durillg pyrolys:is of t.he coated composit.e, the black glass coated composite was place~ under vacuum and was impregnated with soluti.c)n A. Sub~e~uent pyrolysis produccd a hlack glass coating with fewer m~crocrac~s t.han found pri.or to i~pregnation. No macrocracks were induced by heat~ing the coatecl composit.e to 1~00C :in argon with subsequent slow cool.ing.
EXAMPLE III
,.. ............ _ A black glass cont.aining silicon c:arbide coated c~rbon-call)on composite weighing 7.42 grams was heated in a vertical furnace i.n air at. a rate of 200C per hour up to 9~0C. After eight hours at.
950C, the sampl.e was cooled to room temperature at a rate of 200C pe hour. The ~pecimen retained 75X of its weight after undergoing this oxiliation test. Observation of the thermograv;metric analysis thermogram indicated that the weight loss occllrred primarily during t.he -ramp to 950C at 200~C per hour. The ooating consi~;ted of 73o by weight black glass coating and 27~o by weight ~ilioon ~arbi(lc in the coating.
EXAMPLE r~
This ex~mple is included to describe the result when ~n unfilled black glass, made from a cyclosiloxane monomer, was slurried with a monomeric cyclosiloxane similar to the solution A blend prepared as in Example I. Thi~ unfilled black glass slurry was utilized in place of the silicon carbide fillecl blac:k glass slurr~.
An unfilled mixture made by ad~ing 7.2 gr~ms of methylhydrocyclosiloxane to lO.0 grams of l, 3, ~, 7-tetravinyltetra-methylcyclotetrasiloxane in the presence of 90 ppm platinum (the platinum is present in t,he s~me ~orm as in Example I) was polymerized at 55C Eor 80 minutes and subsequently pyrolyzed at 1200C under argon to provide an unfilled black glass. The black glass so produced was reduced to a powder by ball milling and then added to a new portion of the unfilled monomeric cyclosiloxane blend to produce a slurry which was applied to a carbon-carbon co~posite. Each item was infiltrated with Solution A. The infiltration step wns performed in one case at atmospheric pressure and in a second :ase under a vacuum of 29 mm of merc:ury. Each item was pyrolyzed at 1'~00C as in Exclmple I to giYC a ~' black glass coated oomposite. Each coated composite was then heated at l200C in air for about 3 hours and eac:h composite lost about, 80o of its initial weight thus showing that ]ess effective protection is afEorded hy black glags alone.
For c~omparlson, a eonte.d composit:e made using th~ procedure of Exampl~ II was heated in air at 1200C for about 3 hours and ~howed a weight 109s of 23% after the oxidntion test. An uncoated carbon-carbon composite was completely burned out in an identical test.
EXAMPLE V
This example is included in order to point out the difference in quality of the hlack glass coatin~ produced by ~: .
- . : ., -, . .
substituting pure silicon carbide for the black glass containing silicon carbide c-f Examp1e 1. To a new solution A prepared as in Ex~mple I was added ~OX silicon carbide powder to form a slurry. A carbon--arbon composite was coated with this slurry and the coat:ing was cured in a 60C oven for 60 minutes, and subsequently pyrolyzed under argon at 1200G ~or 1 hour. The coating cracked and flaked off. When silicon carbide whiskers were substituted for the silicon carbide powder, a better coating was produced, but neither coating was as good as that in Example II above.
- . , . . : .; :
Claims (30)
1. A method of forming a high temperature oxidation resistant coating on a carbon-carbon composite comprising the steps:
(a) polymerizing a blend of a hydrosilylation catalyst, a filler and 1) a cyclosiloxane monomer of formula where n is an integer from 3 to about 20, R is hydrogen, and R' is an alkene having from 2 to about 20 carbon atoms and containing a vinyl-silicon bond, or 2) at least two different cyclosiloxane monomers of the same formula as above and with the same n integer value range where R' is an alkyl group of from 1 to about 20 carbon atoms and in one cyclosiloxane monomer R is hydrogen, and in the others R is an alkene of from 2 to about 20 carbon atoms containing a vinyl-silicon bond to produce a black glass precursor polymer containing a filler;
(b) pyrolyzing said polymer precursor at pyrolyzing conditions to form a black glass powder containing a filler;
(c) reducing the particle size of the filled black glass powder;
(d) mixing said reduced particle size black glass with a new portion of the blend of the cyclosiloxane monomers and hydrosilylation catalyst and optionally a filler of step (a) to form a slurry;
(e) applying said slurry from step (d) to a carbon-carbon composite;
(f) curing said coated carbon carbon composite at curing conditions to produce a cyclosiloxane polymer coated carbon-carbon composite;
(g) pyrolyzing said filled polymer coated carbon-carbon composite at pyrolyzing conditions to produce a filled black glass containing coating on said carbon-carbon composite; and (h) recovering said filled black glass coated carbon-carbon composite.
(a) polymerizing a blend of a hydrosilylation catalyst, a filler and 1) a cyclosiloxane monomer of formula where n is an integer from 3 to about 20, R is hydrogen, and R' is an alkene having from 2 to about 20 carbon atoms and containing a vinyl-silicon bond, or 2) at least two different cyclosiloxane monomers of the same formula as above and with the same n integer value range where R' is an alkyl group of from 1 to about 20 carbon atoms and in one cyclosiloxane monomer R is hydrogen, and in the others R is an alkene of from 2 to about 20 carbon atoms containing a vinyl-silicon bond to produce a black glass precursor polymer containing a filler;
(b) pyrolyzing said polymer precursor at pyrolyzing conditions to form a black glass powder containing a filler;
(c) reducing the particle size of the filled black glass powder;
(d) mixing said reduced particle size black glass with a new portion of the blend of the cyclosiloxane monomers and hydrosilylation catalyst and optionally a filler of step (a) to form a slurry;
(e) applying said slurry from step (d) to a carbon-carbon composite;
(f) curing said coated carbon carbon composite at curing conditions to produce a cyclosiloxane polymer coated carbon-carbon composite;
(g) pyrolyzing said filled polymer coated carbon-carbon composite at pyrolyzing conditions to produce a filled black glass containing coating on said carbon-carbon composite; and (h) recovering said filled black glass coated carbon-carbon composite.
2. The process of Claim 1 where said filled black glass coated carbon-carbon composite is further impregnated with the blend of step (a), and pyrolyzed to produce a crack-free filled black glass coating on said carbon-carbon composite and recovering said filled black glass coated carbon-carbon composite.
3. The process of Claim 1 where said filler is selected from the group consisting of silicon carbide, silicon nitride, titania, hafnia, zirconia, silica, alumina and mixtures thereof.
4. The process of Claim 3 where the filler is a powder, whisker, or a fiber.
5. The process of Claim 3 where said black glass containing filler has an amount of filler present in the range of from about 20% to about 70% in step (b) of Claim 1 and said coating has an amount of filler in the range of from 15% to about 65% in said coated composite.
6. The process of Claim 2 where said impregnation is applied under a reduced pressure in the range from about 1 mm Hg to about 29 mm Hg and for a time in the range of 1 minute to 60 minutes.
7. The process of Claim 1 where said polymerization takes place at a temperature in the range of from about 25°C to about 300°C, a pressure in the range of from about 14 psi to about 30,000 psi, and a time in the range of from about 1 minute to about 600 minutes.
8. The process of Claim 1 where said pyrolyzing conditions include a temperature in the range of from about 700°C to about 1400°C, and an atmosphere consisting of a non-oxidizing gas.
9. The process of Claim 1 where said filled black glass is present in said monomer mixture of step (d) at from about 20% to about 70%.
10. The process of Claim 1 where said coating comprises an amount of black glass in the range of from about 35% to about 85%.
11. The process of Claim 1 where said curing conditions include a temperature in the range of from about 25°C to about 300°C, for a time in the range of from about 1 minute to about 600 minutes and at a pressure in the range of from about 14 psi to about 30,000 psi.
12. The process of Claim I further characterized in that said cyclosiloxane monomer is 1,3,5,7-tetravinyltetramethyl-cyclotetrasiloxane.
13. The process of Claim 1 further characterized in that said cyclosiloxane monomer is 1,3,5,7-tetrahydrotetramethyl-cyclotetrasiloxane.
14. The process of Claim 1 further characterized in that said cyclosiloxane monomer is 1,3,5,7-tetravinyltetrahydro-cyclotetrasiloxane.
15. The process of Claim 1 further characterized in that said cyclosiloxane monomer is 1,3,5-trivinyltrimethylcyclotrisiloxane.
16. The process of Claim 1 further characterized in that said cyclosiloxane monomer is 1,3,5-trimethyltrihydrocyclotrisiloxane.
17. The process of Claim 1 further characterized in that said hydrosilylation catalyst is a metal compound where said metal is selected from the group consisting of platinum, cobalt and manganese and is present in an amount ranging from about 1 ppm to about 200 ppm as the metal.
18. The product of the proccss of Claim 1.
19. A method of forming a high temperature oxidation resistant coating on a carbon-carbon composite comprising the steps:
(a) applying a blend of a hydrosilylation catalyst and 1) a cyclosiloxane monomer of formula where n is an integer from 3 to about 20, R is hydrogen, and R' is an alkene having from 2 to about 20 carbon atoms and containing a vinyl-silicon bond, or 2) at least two different cyclosiloxane monomers of the same formula as above and with the same n integer value range where R' is an alkyl group of from 1 to about 20 carbon atoms and in one cyclosiloxane monomer R is hydrogen , and in the others R is an alkene of from 2 to about 20 carbon atoms containing a vinyl-silicon bond to a carbon-carbon composite to afford a coated carbon-carbon composite;
(b) curing said coated carbon-carbon composite at curing conditions to produce a cyclosiloxane polymer coated carbon-carbon composite;
(c) pyrolyzing said polymer coated carbon-carbon composite at pyrolyzing conditions to produce a black glass coating on said carbon-carbon composite; and (d) recovering said black glasæ coated carbon-carbon composite.
(a) applying a blend of a hydrosilylation catalyst and 1) a cyclosiloxane monomer of formula where n is an integer from 3 to about 20, R is hydrogen, and R' is an alkene having from 2 to about 20 carbon atoms and containing a vinyl-silicon bond, or 2) at least two different cyclosiloxane monomers of the same formula as above and with the same n integer value range where R' is an alkyl group of from 1 to about 20 carbon atoms and in one cyclosiloxane monomer R is hydrogen , and in the others R is an alkene of from 2 to about 20 carbon atoms containing a vinyl-silicon bond to a carbon-carbon composite to afford a coated carbon-carbon composite;
(b) curing said coated carbon-carbon composite at curing conditions to produce a cyclosiloxane polymer coated carbon-carbon composite;
(c) pyrolyzing said polymer coated carbon-carbon composite at pyrolyzing conditions to produce a black glass coating on said carbon-carbon composite; and (d) recovering said black glasæ coated carbon-carbon composite.
20. The process of Claim 19 further characterized in that said curing conditions include a temperature in the range of from about 25°C to about 300°C, a pressure in the range of from about 14 psi to about 30,000 psi, and a time in the range of from about 1 minute to about 600 minutes.
21. The process of Claim 19 further characterized in that said pyrolyzing conditions include a temperature in the range of from about 700°C to about 1400°C, and an atmosphere consisting of a non-oxidizing gas.
22. The process of Claim 19 further characterizecl in that said cyclosiloxane monomer is 1,3,5-trivinyltrimethylcyclotrisiloxane.
23. The process of Claim 19 further characterized in that said cyclosiloxane monomer is 1,3,5,7-tetravinyltetramethyl-cyclotetrasiloxane.
24. The process of Claim 19 further characterized in that cyclosiloxane monomer is 1,3,5,7-tetrahydrotetramethyl-cyclotetrasiloxane.
25. The process of Claim 19 further characterized in that said cyclosiloxane monomer is 1,3,5,7-tetravinyltetrahydro-cyclotetrasiloxane.
26. The process of Claim 19 further characterized in that said hydrosilylation catalyst is a metal compound where said metal is selected from the group consisting of platinum, cobalt and manganese and is present in an amount ranging from about 1 ppm to about 200 ppm as the metal.
27. The product of the process of Claim 19.
28. A coated carbon-carbon composite comprising not less than 95% by weight of a carbon-carbon composite which has been coated with a filled black glass where said black glass has the composition SiCxOy in which x ranges from about 0.5 to about 2.0, y ranges from about 0.5 to about 3.0, and where the coating contains from about 15% to about 65% weight percent of the filler.
29. The coated composite of Claim 28 further characterized in that the filled black glass contains a filler selected from the group consisting of silicon carbide, silicon nitride, titania, hafnia, zirconia, silica, alumina and mixtures thereof.
30. The coated composite of Claim 28 where said filler is a powder, fiber, or a whisker.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/042,090 US5225283A (en) | 1987-04-24 | 1987-04-24 | Coating for protecting a carbon-carbon composite from oxidative degradation |
| CA002023379A CA2023379A1 (en) | 1987-04-24 | 1990-08-16 | Coating for protecting a carbon-carbon composite for oxidative degradation |
| GB9104677A GB2266300A (en) | 1987-04-24 | 1991-03-06 | A coating for protecting a carbon-carbon composite from oxidative degradation |
| DE4113061A DE4113061A1 (en) | 1987-04-24 | 1991-04-22 | Composite material and method for its production |
| FR9107167A FR2692256A1 (en) | 1987-04-24 | 1991-06-12 | Black glass coating for carbon-carbon composite and its production process. |
| EP93912106A EP0691945A1 (en) | 1990-08-16 | 1993-04-01 | A coating for protecting a carbon-carbon composite from oxidative degradation |
| PCT/US1993/003095 WO1994022788A1 (en) | 1987-04-24 | 1993-04-01 | A coating for protecting a carbon-carbon composite from oxidative degradation |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/042,090 US5225283A (en) | 1987-04-24 | 1987-04-24 | Coating for protecting a carbon-carbon composite from oxidative degradation |
| CA002023379A CA2023379A1 (en) | 1987-04-24 | 1990-08-16 | Coating for protecting a carbon-carbon composite for oxidative degradation |
| PCT/US1993/003095 WO1994022788A1 (en) | 1987-04-24 | 1993-04-01 | A coating for protecting a carbon-carbon composite from oxidative degradation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2023379A1 true CA2023379A1 (en) | 1992-02-17 |
Family
ID=25674263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002023379A Abandoned CA2023379A1 (en) | 1987-04-24 | 1990-08-16 | Coating for protecting a carbon-carbon composite for oxidative degradation |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2023379A1 (en) |
| GB (1) | GB2266300A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112608168A (en) * | 2020-12-18 | 2021-04-06 | 江西信达航科新材料科技有限公司 | High-temperature-resistant and oxidation-resistant ceramic coating and preparation method thereof |
-
1990
- 1990-08-16 CA CA002023379A patent/CA2023379A1/en not_active Abandoned
-
1991
- 1991-03-06 GB GB9104677A patent/GB2266300A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112608168A (en) * | 2020-12-18 | 2021-04-06 | 江西信达航科新材料科技有限公司 | High-temperature-resistant and oxidation-resistant ceramic coating and preparation method thereof |
| CN112608168B (en) * | 2020-12-18 | 2022-08-09 | 江西信达航科新材料科技有限公司 | High-temperature-resistant and oxidation-resistant ceramic coating and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9104677D0 (en) | 1993-07-14 |
| GB2266300A (en) | 1993-10-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5225283A (en) | Coating for protecting a carbon-carbon composite from oxidative degradation | |
| DE68911443T2 (en) | Composite material reinforced with carbon fibers and process for its production. | |
| CA1149116A (en) | High temperature thermal insulation material and method for making same | |
| Riedel et al. | Silicon-based polymer-derived ceramics: synthesis properties and applications-a review dedicated to Prof. Dr. Fritz Aldinger on the occasion of his 65th birthday | |
| US6287639B1 (en) | Composite materials | |
| US4795677A (en) | Oxidation-inhibited carbon-carbon composites | |
| US11773029B2 (en) | Impregnated fibers comprising preceramic resin formulations, and related composite materials and methods | |
| KR100230621B1 (en) | Carbon fiber reinforced silicon nitride based nanocomposite material and method for preparing same | |
| EP1867619B1 (en) | Method of coating a ceramic based felt | |
| CN101939359A (en) | Fire resistant flexible ceramic resin blend and composite products formed therefrom | |
| CA1146598A (en) | Sintered ceramic body and process for production thereof | |
| JP5866844B2 (en) | Method for producing silicon carbide particle reinforced aluminum-silicon based aluminum alloy composite material | |
| JPH02212370A (en) | Composite material | |
| CA2023379A1 (en) | Coating for protecting a carbon-carbon composite for oxidative degradation | |
| JPH05339056A (en) | Oxidation-resistant member composed of carbon-carbon composite having sic doped matrix and production thereof | |
| WO1994015887A1 (en) | Thermostructural composite articles and method for making same | |
| HU216136B (en) | Abrasion-resistant protective oxid-layer for sic-bodies | |
| Ma et al. | Microstructure and oxidation resistance of SiC coated carbon-carbon composites via pressureless reaction sintering | |
| JPH0553850B2 (en) | ||
| JPH06345572A (en) | Oxidation resistant coating layer of c/c composite material | |
| CA1045919A (en) | Chemically bonded aluminum coating for carbon via monocarbides | |
| EP0691945A1 (en) | A coating for protecting a carbon-carbon composite from oxidative degradation | |
| US6670040B1 (en) | Carbon fiber-reinforced carbon composite body and method of manufacturing the same | |
| JP2687181B2 (en) | Composite material | |
| KR20030054077A (en) | Method to coat ceramic powder with TiO2 and Method to improve wettability of B4C-Al composite material |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |