Patent US4761389A successfully refreshed from Google Patents.
US4761389A
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Process for preparing ceramic materials with reduced carbon levels
Assignee: Dow Silicones Corp
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Filing: 1985-04-01
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Granted: 1988-08-02
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Expires: 2005-04-01
Abstract
Abstract A process for preparing ceramic materials with reduced carbon levels is described. The process involves treating a silicon-containing preceramic polymer with ammonia at a temperature of 550°-800° C. for a time sufficient to reduce the carbon content prior to pyrolysis at 900°-1500° C. Another process also involves the pyrolysis of a silicon-containing preceramic polymer in an ammonia atmosphere. The carbon level of ceramic materials produced by this invention can be controlled to a given, desired level by varying the process conditions. Suitable silicon-containing preceramic polymers include polycarbosilanes, polysilazanes, polysilanes, organosilsesquioxane-containing sol-gels, and organopolysiloxanes which are capable of being converted to ceramic materials when fired to elevated temperatures. Ceramic fibers can be prepared by the processes disclosed which contain less than 0.25 weight percent carbon.
Inventors
- 👤 James A. Rabe
- 👤 Duane R. Bujalski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:06
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565; C04B35/571; C04B35/58; C04B35/584; C04B35/589
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
96 words
A process for preparing a ceramic material with reduced carbon level comprising (A) heating a silicon-containing preceramic polymer at a temperature of about 550°-800° C. in an ammonia-containing atmosphere for a time sufficient to reduce the carbon level of the silicon-containing preceramic polymer wherein said ammonia-containing atmosphere contains 0-99 volume percent inert atmosphere and 1-100 volume percent ammonia and then (B) heating the material formed in step (A) to a temperature of 900-1500° C. in an inert atmosphere, vacuum, or in the presence of ammonia gas until a ceramic material with reduced carbon level is obtained.
Claim 2
Dependent Claim
96 words
A process for preparing a ceramic material with reduced carbon level comprising (A) heating a silicon-containing preceramic polymer at a temperature of about 550°-800° C. in an ammonia-containing atmosphere for a time sufficient to reduce the carbon level of the silicon-containing preceramic polymer wherein said ammonia-containing atmosphere contains 0-99 volume percent inert atmosphere and 1-100 volume percent ammonia and then (B) heating the material formed in step (A) to a temperature of 900-1500° C. in an inert atmosphere, vacuum, or in the presence of ammonia gas until a ceramic material with reduced carbon level is obtained.
Claim 3
Dependent Claim
22 words
A process as defined in claim 1 wherein said ammonia-containing atmosphere contains 0-78 volume percent inert gas and 22-100 volume percent ammonia.
Claim 4
Dependent Claim
15 words
A process as defined in claim 1 wherein said silicon-containing preceramic polymer is a polycarbosilane.
Claim 5
Dependent Claim
15 words
A process as defined in claim 2 wherein said silicon-containing preceramic polymer is a polycarbosilane.
Claim 6
Dependent Claim
140 words
A process as defined in claim 3 wherein said polycarbosilane is prepared by thermally decomposing and polycondensing a polysilane or polysilanes by heating said polysilane or polysilanes at a temperature of 300°-700° C. in an inert gas, hydrogen, or vacuum wherein said polysilane or polysilanes are selected from the group consisting of cyclic polysilanes of the general formula (R.sup.1 R.sup.2 Si).sub.n and linear polysilanes of the general formula ##STR2## where n is greater than or equal to 4; where m is greater than or equal to 2; and where R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of hydrogen, alkyl groups containing 1 to 4 carbon atoms, phenyl, --Si(R 5 ) 3 groups where R 5 is a alkyl group containing 1 to 4 carbon atoms, and halogen atoms.
Claim 7
Dependent Claim
139 words
A process as defined in claim 4 wherein said polycarbosilane is prepared by thermally decomposing and polycondensing a polysilane or polysilanes by heating said polysilane or polysilanes at a temperature of 300°-700° C. in an inert gas, hydrogen, or vacuum wherein said polysilane or polysilanes are selected from the group consisting of cyclic polysilanes of the general formula (R.sup.1 R.sup.2 Si).sub.n and linear polysilanes of the general formula ##STR3## where n is greater than or equal to 4; where m is greater than or equal to 2; and where R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of hydrogen, alkyl groups containing 1 to 4 carbon atoms, phenyl, --Si(R 5 )3 groups where R 5 is a alkyl group containing 1 to 4 carbon atoms, and halogen atoms.
Claim 8
Dependent Claim
15 words
A process as defined in claim 1 wherein said silicon-containing preceramic polymer is a polysilazane.
Claim 9
Dependent Claim
15 words
A process as defined in claim 2 wherein said silicon-containing preceramic polymer is a polysilazane.
Claim 10
Dependent Claim
113 words
A process as defined in claim 7 wherein said polysilazane is prepared by prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, an organochlorosilane or a mixture of organochlorosilanes of the general formula R'.sub.c SiCl.sub.(4-c) with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; and c has a value of 1 or 2.
Claim 11
Dependent Claim
111 words
A process as defined in claim 8 wherein said polysilazane is prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, an organochlorosilane or a mixture of organochlorosilanes of the general formula R'.sub.c SiCl.sub.(4-c) with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; and c has a value of 1 or 2.
Claim 12
Dependent Claim
126 words
A process as defined in claim 7 wherein said polysilazane is prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, a chlorine-containing disilane or a mixture of chlorine-containing disilanes, of the general formula (Cl.sub.d R'.sub.e Si).sub.2 with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; d has a value of 0.5-3; e has a value of 0-2.5 and the sum of (d+e) is equal to three.
Claim 13
Dependent Claim
126 words
A process as defined in claim 8 wherein said polysilazane is prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, a chlorine-containing disilane or a mixture of chlorine-containing disilanes, of the general formula (Cl.sub.d R'.sub.e Si).sub.2 with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; d has a value of 0.5-3; e has a value of 0-2.5 and the sum of (d+e) is equal to three.
Claim 14
Dependent Claim
152 words
A process as defined in claim 7 wherein said polysilazane is prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, a mixture of (1) chlorine-containing disilane or a mixture of chlorine-containing disilanes, of the general formula (Cl.sub.d R'.sub.e Si).sub.2 and (2) an organochlorosilane or a mixture of organochlorosilanes of the general formula R'.sub.c SiCl.sub.(4-c) with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; d has a value of 0.5-3; e has a value of 0-2.5; the sum of (d+e) is equal to three; and c has a value of 1 or 2.
Claim 15
Dependent Claim
152 words
A process as defined in claim 8 wherein said polysilazane is prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, a mixture of (1) chlorine-containing disilane or a mixture of chlorine-containing disilanes, of the general formula (Cl.sub.d R'.sub.e Si).sub.2 and (2) an organochlorosilane or a mixture of organochlorosilanes of the general formula R'.sub.c SiCl.sub.(4-c) with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; d has a value of 0.5-3; e has a value of 0-2.5; the sum of (d+e) is equal to three; and c has a value of 1 or 2.
Claim 16
Dependent Claim
74 words
A process as defined in claim 7 wherein said polysilazanes is prepared by contacting and reacting in an inert, essentially anhydrous atmosphere, trichlorosilane with a disilazane at a temperature in the range of 25° C. to 300° C. while removing byproduced volatile products, wherein said disilazane has the general formula (R.sub.3 Si).sub.2 NH where R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms.
Claim 17
Dependent Claim
74 words
A process as defined in claim 8 wherein said polysilazanes is prepared by contacting and reacting in an inert, essentially anhydrous atmosphere, trichlorosilane with a disilazane at a temperature in the range of 25° C. to 300° C. while removing byproduced volatile products, wherein said disilazane has the general formula (R.sub.3 Si).sub.2 NH where R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms.
Claim 18
Dependent Claim
15 words
A process as defined in claim 1 wherein said silicon-containing preceramic polymer is a polysilane.
Claim 19
Dependent Claim
15 words
A process as defined in claim 2 wherein said silicon-containing preceramic polymer is a polysilane.
Claim 20
Dependent Claim
16 words
A process as defined in claim 1 wherein said silicon-containing preceramic polymer is an organosilsesquioxane-containing sol-gel.
Claim 21
Dependent Claim
16 words
A process as defined in claim 2 wherein said silicon-containing preceramic polymer is an organosilsesquioxane-containing sol-gel.
Claim 22
Dependent Claim
15 words
A process as defined in claim 1 wherein said silicon-containing preceramic polymer is an organopolysiloxane.
Claim 23
Dependent Claim
15 words
A process as defined in claim 2 wherein said silicon-containing preceramic polymer is an organopolysiloxane.
Claim 24
Dependent Claim
47 words
A process for preparing a ceramic material with reduced carbon levels comprising heating a silicon-containing preceramic polymer in the presence of ammonia gas in a thermally staged sequence up to and including temperatures in excess of 900° C. to obtain a ceramic material with reduced carbon levels.
Claim 25
Dependent Claim
47 words
A process for preparing a ceramic material with reduced carbon levels comprising heating a silicon-containing preceramic polymer in the presence of ammonia gas in a thermally staged sequence up to and including temperatures in excess of 900° C. to obtain a ceramic material with reduced carbon levels.
Claim 26
Dependent Claim
26 words
A process as defined in claim 23 wherein said silicon-containing preceramic polymer is selected from the group consisting of polycarbosilanes, polysilazanes, polysilanes, organosilsesquioxane-containing sol-gels, and organopolysiloxanes.
Claim 27
Dependent Claim
144 words
A process as defined in claim 23 wherein said silicon-containing preceramic polymer is a polycarbosilane prepared by thermally decomposing and polycondensing a polysilane or polysilanes by heating said polysilane or polysilanes at a temperature of 300°-700° C. in an inert gas, hydrogen, or vacuum wherein said polysilane or polysilanes are selected from the group consisting of cyclic polysilanes of the general formula (R.sup.1 R.sup.2 Si).sub.n and linear polysilanes of the general formula ##STR4## where n is greater than or equal to 4; where m is greater than or equal to 2; and where R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of hydrogen, alkyl groups containing 1 to 4 carbon atoms, phenyl, --Si(R 5 ) 3 groups where R 5 is a alkyl group containing 1 to 4 carbon atoms, and halogen atoms.
Claim 28
Dependent Claim
115 words
A process as defined in claim 23 wherein said silicon-containing preceramic polymer is a polysilazane prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, an organochlorosilane or a mixture of organochlorosilanes of the general formula R'.sub.c SiCl.sub.(4-c) with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms, and c has a value of 1 or 2.
Claim 29
Dependent Claim
131 words
A process as defined in claim 23 wherein said silicon-containing preceramic polymer is a polysilazane prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, a chlorine-containing disilane or a mixture of chlorine-containing disilanes, of the general formula (Cl.sub.d R'.sub.e Si ).sub.2 with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; d has a value of 0.5-3; e has a value of 0-2.5 and the sum of (d+e) is equal to three.
Claim 30
Dependent Claim
156 words
A process as defined in claim 23 wherein said silicon-containing preceramic polymer is a polysilazane prepared by contacting and reacting in an inert, essentially anhydrous, atmosphere, a mixture of (1) chlorine-containing disilane or a mixture of chlorine-containing disilanes, of the general formula (Cl.sub.d R'.sub.e Si).sub.2 and (2) an organochlorosilane or a mixture of organochlorosilanes of the general formula R'.sub.c SiCl.sub.(4-c) with a disilazane having the general formula (R.sub.3 Si).sub.2 NH at a temperature in the range of 25° C. to 300° C. while distilling byproduced volatile products, wherein R' is selected from the group consisting of vinyl, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; R is selected from the group consisting of vinyl, hydrogen, phenyl, and alkyl radicals containing 1 to 3 carbon atoms; d has a value of 0.5-3; e has a value of 0-2.5; the sum of (d+e) is equal to three; and c has a value of 1 or 2.
Claim 31
Dependent Claim
78 words
A process as defined in claim 23 wherein said silicon-containing preceramic polymer is a polysilazane prepared by contacting and reacting in an inert, essentially anhydrous atmosphere, trichlorosilane with a disilazane at a temperature in the range of 25° C. to 300° C. while removing byproduced volatile products, wherein said disilazane has the general formula (R.sub.3 Si).sub.2 NH where R is selected from the group consisting of vinyl, hydrogen, phenyl and alkyl radicals containing 1 to 3 carbon atoms.
References Cited (Backward Citations)
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