Patent DE712069C successfully refreshed from Google Patents.
Patent US4514370A successfully refreshed from Google Patents.
US4514370A
Expired / Lapsed
US
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Process for preparing silicon nitride powder
Assignee: Coorstek KK
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Filing: 1984-06-08
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Granted: 1985-04-30
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Expires: 2004-06-08
Abstract
Abstract Disclosed is a process for preparing silicon nitride powder, which comprises baking a powdery mixture comprising (i) 1 part by weight of silica powder, or a silica-containing substance in terms of silica, (ii) 0.4 to 4 parts by weight of carbon powder, or a substance generating carbon by baking, in terms of carbon and (iii) 0.005 to 1 part by weight of silicon nitride powder synthesized by a silica reduction method, at a temperature of from 1350° to 1550° C. in a non-oxidative atmosphere containing nitrogen.
Inventors
- 👤 Hiroshi Inoue
- 👤 Katsutoshi Komeya
- 👤 Akihiko Tsuge
- 👤 Kazunari Koide
- 👤 Masaaki Mori
- 👤 Tetsuro Urakawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:30
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01B21/0685; C01P; C01P2004/00; C01P2004/50; C01P2004/60; C01P2004/61; C01P2004/62
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
84 words
A process for preparing silicon nitride powder, which comprises baking a powdery mixture comprising (i) 1 part by weight of silica powder, or a silica-containing substance in terms of silica, (ii) 0.4 to 4 parts by weight of carbon powder, or a substance generating carbon by baking, in terms of carbon and (iii) 0.005 to 1 part by weight of silicon nitride powder synthesized by a silica reduction method, at a temperature of from 1350° to 1550° C. in a nonoxidative atmosphere containing nitrogen.
Claim 2
Dependent Claim
84 words
A process for preparing silicon nitride powder, which comprises baking a powdery mixture comprising (i) 1 part by weight of silica powder, or a silica-containing substance in terms of silica, (ii) 0.4 to 4 parts by weight of carbon powder, or a substance generating carbon by baking, in terms of carbon and (iii) 0.005 to 1 part by weight of silicon nitride powder synthesized by a silica reduction method, at a temperature of from 1350° to 1550° C. in a nonoxidative atmosphere containing nitrogen.
Claim 3
Dependent Claim
25 words
The process according to claim 1, wherein silicon nitride powder having grain size of 0.1 to 2 μm is employed as said silicon nitride powder.
Claim 4
Dependent Claim
27 words
The process according to claim 1, wherein silicon nitride powder containing not less than 50% of α-Si 3 N 4 is employed as said silicon nitride powder.
Claim 5
Dependent Claim
74 words
The process according to claim 1, wherein said silica reduction method is carried out by subjecting a powdery mixture comprising 1 part by weight of silica powder and 0.4 to 4 parts by weight of carbon powder together with or without 0.005 to 1 part by weight of silicon nitride powder and/or silicon carbide powder, to a heat treatment at a temperature of from 1400° to 1550° C. in a non-oxidative atmosphere containing nitrogen.
Claim 6
Dependent Claim
27 words
The process according to claim 1, wherein said silicon nitride powder synthesized by a silica reduction method is obtained by the process as defined in claim 1.
Claim 7
Dependent Claim
15 words
The process according to claim 1, wherein said silica containing substance is a methylsilicic acid.
Claim 8
Dependent Claim
27 words
The process according to claim 1, wherein said substance generating carbon by baking is selected from the group consisting of phenol-formaldehyde resin, resorcinolformaldehyde resin, polystyrene and hydrocarbon.
Claim 9
Dependent Claim
31 words
The process of claim 1, further comprising the step of recycling a portion of the silicon nitride powder product to the process to be used as said starting silicon nitride powder.
Claim 10
Dependent Claim
25 words
The process according to claim 1, wherein said silica powder or said silica-containing substances has a grain size equal to or less than 1 μm.
Claim 11
Dependent Claim
24 words
The process according to claim 9, wherein said silica powder or said silica-containing substance has a grain size from about 0.01 to 0.95 μm.
Claim 12
Dependent Claim
19 words
The process of claim 2, wherein said silicon nitride powder has a grain size of 0.2 to 1 μm.
Claim 13
Dependent Claim
27 words
The process of claim 1, further comprising the step of heat treating the baked product at a temperature from 600° to 800° C. in an oxidative atmosphere.
Claim 14
Dependent Claim
120 words
A process for preparing silicon nitride powder, comprising the steps of: preparing a starting silicon nitride powder by the silica reduction method by heat treating said starting silicon nitride powder at a temperature of 1400° to 1550° C. in a non-oxidative atmosphere containing nitrogen; adding 0.005 to 1 part by weight of said silicon nitride powder with (i) 1 part by weight in terms of silica of silica powder or a silica-containing substance; and (ii) 0.4 to 4 parts by weight in terms of carbon of carbon powder, or a substance generating carbon upon baking, to form a powdery mixture; and baking said powdery mixture at a temperature of from 1350° to 1550° C. in a nonoxidative atmosphere containing nitrogen.
Claim 15
Dependent Claim
120 words
A process for preparing silicon nitride powder, comprising the steps of: preparing a starting silicon nitride powder by the silica reduction method by heat treating said starting silicon nitride powder at a temperature of 1400° to 1550° C. in a non-oxidative atmosphere containing nitrogen; adding 0.005 to 1 part by weight of said silicon nitride powder with (i) 1 part by weight in terms of silica of silica powder or a silica-containing substance; and (ii) 0.4 to 4 parts by weight in terms of carbon of carbon powder, or a substance generating carbon upon baking, to form a powdery mixture; and baking said powdery mixture at a temperature of from 1350° to 1550° C. in a nonoxidative atmosphere containing nitrogen.
References Cited (Backward Citations)
JPS5238500A
Cited
DE2642554A1
Cited
DE2814235A1
Cited
JPS53102300A
Cited
US4428916A
Cited
GB1579417A
Cited
US4264565A
Cited
US4368180A
Cited
EP0047143A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1988-04-29 | 1988-10-29 | 1989-04-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-29 | 1992-10-29 | 1993-04-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-29 | 1996-10-29 | 1997-04-30 | $7700.00 | Window Closed / Lapsed |