US5055431A
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US
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Polysilazanes and related compositions, processes and uses
Assignee: SRI International Inc
•
Filing: 1990-04-03
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Granted: 1991-10-08
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Expires: 2010-04-03
Abstract
Abstract Silazanes and related compounds are prepared by providing a precursor containing one or more cyclic silazane units, causing polymerization to occur in the presence of a transition metal catalyst to form a polysilazane product. Further products may result from additional reaction. The novel compounds may be pyrolyzed to yield ceramic materials such as silicon nitride, silicon carbide and mixtures thereof. In a preferred embodiment, substantially pure silicon nitride and articles prepared therefrom are provided. Fibers, coatings, binders and the like may be prepared from the novel materials.
Inventors
- 👤 Yigal D. Blum
- 👤 Edward J. Crawford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:55
CPC Classifications
C; C07; C07F; C07F7/00; C07F7/02; C07F7/08; C07F7/10; C04; C04B; C04B35/00; C04B35/01; C04B35/16; C04B35/18; C04B35/185; C04B35/515; C04B35/56; C04B35/565; C04B35/571; C04B41/00; C04B41/45; C04B41/4505; C04B41/455; C04B41/4554; C07F7/21; C08; C08G; C08G77/00; C08G77/04; C08G77/38; C08G77/382; C08G77/398; C08G77/48; C08G77/54; C08G77/60; C08G77/62; C08G79/00
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
121 words
A method of making a ceramic composition, comprising pyrolyzing at a temperature in the range of about 500° C. to about 1800° C. a polysilazane consisting essentially of n recurring units of the structures ()I) or (II) or both ##STR14## wherein m is an integer, the R substituents may be the same or different and are selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl, aryl, and amino, unsubstituted or substituted with 1 or 2 lower alkyl groups, X is --NR', --NR'--NR'--or --NR'--Y--NR' where Y is lower alkyl or silyl, and the R' and R" may be the same or different and are independently selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl and aryl.
Claim 2
Independent Claim
121 words
A method of making a ceramic composition, comprising pyrolyzing at a temperature in the range of about 500° C. to about 1800° C. a polysilazane consisting essentially of n recurring units of the structures ()I) or (II) or both ##STR14## wherein m is an integer, the R substituents may be the same or different and are selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl, aryl, and amino, unsubstituted or substituted with 1 or 2 lower alkyl groups, X is --NR', --NR'--NR'--or --NR'--Y--NR' where Y is lower alkyl or silyl, and the R' and R" may be the same or different and are independently selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl and aryl.
Claim 3
Independent Claim
134 words
A method of making a ceramic composition, comprising pyrolyzing at a temperature in the range of about 500° C. to 1100° C. a polysilazane consisting essentially of n recurring units of the structures (I) or (II) or both ##STR15## wherein m is an integer, the R substituents may be the same or different and are selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl, aryl, and amino, unsubstituted or substituted with 1 or 2 lower alkyl groups, X is --NR', --NR'--NR----or --NR'--Y--NR' where Y is lower alkyl or silyl, and the R' and R" may be the same or different and are independently selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl and aryl, wherein the polysilazane is provided as a coating on a substrate prior to pyrolysis.
Claim 4
Independent Claim
134 words
A method of making a ceramic composition, comprising pyrolyzing at a temperature in the range of about 500° C. to 1100° C. a polysilazane consisting essentially of n recurring units of the structures (I) or (II) or both ##STR15## wherein m is an integer, the R substituents may be the same or different and are selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl, aryl, and amino, unsubstituted or substituted with 1 or 2 lower alkyl groups, X is --NR', --NR'--NR----or --NR'--Y--NR' where Y is lower alkyl or silyl, and the R' and R" may be the same or different and are independently selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl and aryl, wherein the polysilazane is provided as a coating on a substrate prior to pyrolysis.
Claim 5
Independent Claim
161 words
A method of making ceramic articles, comprising: providing a solution of a polymer consisting essentially of n units of the structures (I) or (II) or both ##STR16## wherein m is 0 or an integer, n is an integer greater than 1, the R substituents may be the same or different and are selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl, aryl, and amino, unsubstituted or substituted with 1 or 2 lower alkyl groups, X is --NR'--, NR'--NR' or --NR'--Y--NR'--where Y is lower alkyl or silyl, and the R' and R" may be the same or different and are independently selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl and aryl; admixing said polymer solution with ceramic powders, ceramic whiskers, ceramic fibers, or with a porous or nonporous ceramic article; and thermally treating said admixture at a temperature in the range of about 500° C. to 1600° C. so as to form a ceramic article.
Claim 6
Independent Claim
161 words
A method of making ceramic articles, comprising: providing a solution of a polymer consisting essentially of n units of the structures (I) or (II) or both ##STR16## wherein m is 0 or an integer, n is an integer greater than 1, the R substituents may be the same or different and are selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl, aryl, and amino, unsubstituted or substituted with 1 or 2 lower alkyl groups, X is --NR'--, NR'--NR' or --NR'--Y--NR'--where Y is lower alkyl or silyl, and the R' and R" may be the same or different and are independently selected from the group consisting of hydrogen, lower alkyl, lower alkenyl, silyl and aryl; admixing said polymer solution with ceramic powders, ceramic whiskers, ceramic fibers, or with a porous or nonporous ceramic article; and thermally treating said admixture at a temperature in the range of about 500° C. to 1600° C. so as to form a ceramic article.
Claim 7
Dependent Claim
24 words
The method of claim 1, wherein the polysilazane contains n recurring units of the structure (I), and n is an integer greater than 1.
Claim 8
Dependent Claim
24 words
The method of claim 1, wherein the polysilazane contains n recurring units of the structure (II), and n is an integer greater than 1.
Claim 9
Dependent Claim
15 words
The method of claim 1, wherein the pyrolyzing is carried out in an inert atmosphere.
Claim 10
Dependent Claim
11 words
The method of claim 6, wherein the inert atmosphere is nitrogen.
Claim 11
Dependent Claim
11 words
The method of claim 6, wherein the inert atmosphere is argon.
Claim 12
Dependent Claim
15 words
The method of claim 1, wherein the pyrolyzing is carried out in a reactive atmosphere.
Claim 13
Dependent Claim
11 words
The method of claim 9, wherein the reactive atmosphere is ammonia.
Claim 14
Dependent Claim
13 words
The method of claim 9, wherein the reactive atmosphere is hydrogen peroxide vapor.
Claim 15
Dependent Claim
12 words
The method of claim 9, wherein the reactive atmosphere is water vapor.
Claim 16
Dependent Claim
13 words
The method of claim 9, wherein the reactive atmosphere is N 2 O.
Claim 17
Dependent Claim
23 words
The method of claim 1, wherein the pyrolyzing is carried out at a heating rate of 0.1° C. to 10° C. per minute.
Claim 18
Dependent Claim
14 words
The method of claim 1, wherein the pyrolyzing is carried out using flash pyrolysis.
Claim 19
Dependent Claim
17 words
The method of claim 1, wherein the pyrolyzing is carried out in the presence of a catalyst.
Claim 20
Dependent Claim
15 words
The method of claim 1, wherein the pyrolyzing includes at least one isothermal holding step.
Claim 21
Dependent Claim
23 words
The method of claim 2, wherein the substrate is of a material selected from the group consisting of metal, glass, ceramics and graphite.
Claim 22
Dependent Claim
34 words
The method of claim 2, wherein the polysilazane is provided in a solvent, and wherein the polysilazane is present in said solvent at a concentration of between about 0.1 and about 100 wt. %.
Claim 23
Dependent Claim
25 words
The method of claim 2, wherein the polysilazane is provided in a solvent, and wherein the polysilazane of between about 5 and 10 wt. %.
Claim 24
Dependent Claim
15 words
The method of claim 2, wherein said coating involves dipping the substrate in the polysilazane.
Claim 25
Dependent Claim
15 words
The method of claim 2, wherein said coating involves spraying the substrate with the polysilazane.
Claim 26
Dependent Claim
15 words
The method of claim 2, wherein said coating involves painting the substrate with the polysilazane.
Claim 27
Dependent Claim
11 words
The method of claim 1, wherein the polysilazane the structure. ##STR17##
Claim 28
Dependent Claim
12 words
The method of claim 1, wherein the polysilazane contains the structure ##STR18##
Claim 29
Dependent Claim
12 words
The method of claim 1, wherein the polysilazane contains the structure. ##STR19##
Claim 30
Dependent Claim
12 words
The method of claim 1, wherein the polysilazane contains the structure ##STR20##
Claim 31
Dependent Claim
12 words
The method of claim 2, wherein the polysilazane contains the structure ##STR21##
Claim 32
Dependent Claim
12 words
The method of claim 2, wherein the polysilazane contains the structure ##STR22##
Claim 33
Dependent Claim
12 words
The method of claim 2, wherein the polysilazane contains the structure ##STR23##
Claim 34
Dependent Claim
12 words
The method of claim 2, wherein the polysilazane contains the structure ##STR24##
Claim 35
Dependent Claim
25 words
The method of claim 19, wherein said pyrolyzing is carried out at a temperature in the range of about 500° C. to about 900° C.
Claim 36
Dependent Claim
26 words
The method of claim 22, wherein said thermally treating is carried out at a temperature in the range of about 500° C. to about 900° C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-10-07 | 1995-04-08 | 1995-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-10-07 | 1999-04-08 | 1999-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-10-07 | 2003-04-08 | 2003-10-08 | $7700.00 | Window Closed / Lapsed |