US4374793A
Expired / Lapsed
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Method of producing dense sintered silicon carbide body from polycarbosilane
Assignee: Kyoto Ceramic Co Ltd
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Filing: 1978-01-27
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Granted: 1983-02-22
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Expires: 1998-01-27
Abstract
Abstract A method of producing a dense sintered silicon carbide body, which is high in flexural strength, purity and strength at an elevated temperature, from polycarbosilanes is disclosed. This method comprises the following steps of: A. polymerizing organosilicon compounds to obtain insoluble and unmeltable polycarbosilane of which the melting or softening temperature lies higher than its thermal decomposition temperature; B. grinding this insoluble and unmeltable polycarbosilane to powder; C. decomposing this powder thermally in the range of 600° to 2200° C. in a nonoxidizing atmosphere to obtain silicon carbide; D. molding this silicon carbide powder; and E. sintering the thus molded body in a nonoxidizing atmosphere.
Inventors
- 👤 Kazunori Koga
- 👤 Saburo Nagano
- 👤 Shinichiro Mizuta
- 👤 Masayoshi Nakayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 00:00
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565; C04B35/575; C01; C01B; C01B32/00; C01B32/90; C01B32/914; C01B32/956; C01B32/963; C01B32/977; C04B35/571; C01P; C01P2006/00; C01P2006/10; C01P2006/90
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
117 words
A method of producing a dense sintered silicon carbide body from polycarbosilane, which comprises the steps of: (a) polymerizing an organosilicon compound to which has been added a sintering aid so as to form a polycarbosilane containing said sintering aid, said polycarbosilane being insoluble in organic solvents and having a melting or softening temperature which is higher than its thermal decomposition temperature; (b) forming said polycarbosilane into powder; (c) thermally decomposing said powder at 600° to 2200° in a nonoxidizing atmosphere to obtain silicon carbide containing said sintering aid; (d) molding said silicon carbide powder; and (e) sintering the molded body formed in step (d) in a nonoxidizing atmosphere thereby forming a dense, sintered silicon carbide body.
Claim 2
Independent Claim
117 words
A method of producing a dense sintered silicon carbide body from polycarbosilane, which comprises the steps of: (a) polymerizing an organosilicon compound to which has been added a sintering aid so as to form a polycarbosilane containing said sintering aid, said polycarbosilane being insoluble in organic solvents and having a melting or softening temperature which is higher than its thermal decomposition temperature; (b) forming said polycarbosilane into powder; (c) thermally decomposing said powder at 600° to 2200° in a nonoxidizing atmosphere to obtain silicon carbide containing said sintering aid; (d) molding said silicon carbide powder; and (e) sintering the molded body formed in step (d) in a nonoxidizing atmosphere thereby forming a dense, sintered silicon carbide body.
Claim 3
Dependent Claim
45 words
A method as claimed in claim 1, wherein said sintering aid is selected from the group consisting of B, Al, Fe, Ti and W compounds and mixtures thereof, said sintering aid being present in an amount of 0.1 to 3.0% by weight of said polycarbosilane.
Claim 4
Dependent Claim
29 words
A method as claimed in claim 1, wherein said thermal decomposition process step (c) is conducted at 1000° to 1500° C., and the resultant silicon carbide is substantially amorphous.
Claim 5
Dependent Claim
27 words
A method as claimed in claim 1, wherein said sintering process step (e) is carried out at 1900° to 2200° C. in an atmosphere under reduced pressure.
Claim 6
Dependent Claim
24 words
A method as claimed in claim 1, wherein said sintering process step (e) is performed at 1900° to 2200° C. in a hot press.
Claim 7
Independent Claim
100 words
A method for producing a dense, sintered silicon carbide body from polycarbosilane comprising the steps of: (a) polymerizing a organosilicon so as to form a polycarbosilane which is insoluble in organic solvent and has a melting or softening temperature which is higher than its thermal decomposition temperature; (b) forming said polycarbosilane into a powder; (c) thermally decomposing said powder at 600° to 2200° C. in a nonoxidizing atmosphere to obtain silicon carbide; (d) molding said silicon carbide powder; and (e) sintering the molded body formed in step (d) in a nonoxidizing atmosphere thereby forming a dense, sintered silicon carbide body.
Claim 8
Independent Claim
100 words
A method for producing a dense, sintered silicon carbide body from polycarbosilane comprising the steps of: (a) polymerizing a organosilicon so as to form a polycarbosilane which is insoluble in organic solvent and has a melting or softening temperature which is higher than its thermal decomposition temperature; (b) forming said polycarbosilane into a powder; (c) thermally decomposing said powder at 600° to 2200° C. in a nonoxidizing atmosphere to obtain silicon carbide; (d) molding said silicon carbide powder; and (e) sintering the molded body formed in step (d) in a nonoxidizing atmosphere thereby forming a dense, sintered silicon carbide body.
Claim 9
Dependent Claim
42 words
A method according to claim 6 wherein said polymerization step (a) comprises heating the organosilicon for a sufficient length of time so as to produce said insoluble polycarbosilane having a melting or softening temperature which is higher than its thermal decomposition temperature.
Claim 10
Dependent Claim
22 words
A method according to claim 7 wherein said organosilicon is heated in step (a) to a temperature of at least 490° C.
Claim 11
Dependent Claim
19 words
A method according to claim 6 wherein said organosilicon is selected from the group consisting of dimethyldichlorosilane, dodecamethylhexacyclosilane, 1,1,3,3-tetramethyl-disilacyclotritane.
Claim 12
Independent Claim
115 words
A method of producing a dense sintered silicon carbide body from polycarbosilane, which comprises the steps of: (a) polymerizing an organosilicon compound so as to form a polycarbosilane which is insoluble organic solvent and has a melting or softening temperature which is higher than its thermal decomposition temperature; (b) forming said polycarbosilane into a powder; (c) thermally decomposing said powder at 600° to 2200° in a nonoxidizing atmosphere to obtained silicon carbide powder; (d) adding a sintering aid to said silicon carbide powder; (e) molding said silicon carbide powder and sintering aid mixture; and (f) sintering the molded body formed in step (e) in a nonoxidizing atmosphere thereby forming said dense sintered silicon carbide body.
Claim 13
Independent Claim
115 words
A method of producing a dense sintered silicon carbide body from polycarbosilane, which comprises the steps of: (a) polymerizing an organosilicon compound so as to form a polycarbosilane which is insoluble organic solvent and has a melting or softening temperature which is higher than its thermal decomposition temperature; (b) forming said polycarbosilane into a powder; (c) thermally decomposing said powder at 600° to 2200° in a nonoxidizing atmosphere to obtained silicon carbide powder; (d) adding a sintering aid to said silicon carbide powder; (e) molding said silicon carbide powder and sintering aid mixture; and (f) sintering the molded body formed in step (e) in a nonoxidizing atmosphere thereby forming said dense sintered silicon carbide body.
Claim 14
Dependent Claim
55 words
A method as claimed in claim 10, wherein said sintering aid is selected from the group consisting of B, Al, Fe, ti and W compounds and mixtures thereof, said sintering aid being mixed with said silicon carbide powder at the rate of 0.3 to 1.0% by weight to the weight of the silicon carbide body.
Claim 15
Dependent Claim
29 words
A method as claimed in claim 10, wherein said thermal decomposition process step (c) is conducted at 1000° to 1500° C. and the resultant silicon carbide is substantially amorphous.
Claim 16
Dependent Claim
26 words
A method as claimed in claim 10, wherein said sintering process step (f) is carried out at 1900° to 2200° in an atmosphere under reduced pressure.
Claim 17
Dependent Claim
24 words
A method as claimed in claim 10, wherein said sintering process step (f) is conducted at 1900° to 2200° C. in a hot press.
Claim 18
Dependent Claim
42 words
A method according to claim 10 wherein said polymerization step (a) comprises heating the organosilicon for a sufficient length of time so as to produce said insoluble polycarbosilane having a melting or softening temperature which is higher than its thermal decomposition temperature.
Claim 19
Dependent Claim
22 words
A method according to claim 10 wherein said organosilicon is heated in step (a) to a temperature of at least 490° C.
Claim 20
Dependent Claim
42 words
A method according to claim 1 wherein said polymerization step (a) comprises heating the organosilicon for a sufficient length of time so as to produce said insoluble polycarbosilane having a melting or softening temperature which is higher than its thermal decomposition temperature.
Claim 21
Dependent Claim
22 words
A method according to claim 2 wherein said organosilicon is heated in step (a) to a temperature of at least 490° C.
Claim 22
Dependent Claim
28 words
A method as claimed in claim 6, wherein said thermal decomposition step (c) is performed at 1000° to 1500° C. and the resultant silicon carbide is substantially amorphous.
Claim 23
Dependent Claim
21 words
A method as claimed in claim 6, wherein said sintering process step (e) is conducted in an atmosphere under reduced pressure.
Claim 24
Dependent Claim
20 words
A method as claimed in claim 6, wherein said sintering process step (e) is carried out in a hot press.
Claim 25
Dependent Claim
20 words
A method as claimed in claim 6, wherein said sintering process step (e) is performed at 1900° to 2200° C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-21 | 1986-08-23 | 1987-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-21 | 1990-08-23 | 1991-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-21 | 1994-08-23 | 1995-02-22 | $7700.00 | Window Closed / Lapsed |