US4396587A
Expired / Lapsed
US
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Method for manufacture of silicon nitride
Assignee: Asahi Kasei Corp
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Filing: 1981-08-18
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Granted: 1983-08-02
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Expires: 2001-08-18
Abstract
Abstract Silicon nitride of improved quality is obtained by using a liquid silicic acid or modified liquid silicic acid as a silicic substance and carbon in a powdered form, a precursor of carbon in a powdered form, or a precursor of carbon in the form of a solution as a carbonaceous substance, and thermally treating these raw materials in a non-oxidative atmosphere containing nitrogen. By this method, α-type silicon nitride can be easily obtained. Particularly, finely divided α-type silicon nitride suitable for use as the raw material for the production of high-strength sintered articles is also produced. α-type silicon nitride whiskers useful as a reinforcing material for ceramic and metallic articles is also obtained.
Inventors
- 👤 Masami Yamaguchi
- 👤 Yoshirou Tajitsu
- 👤 Yoshiharu Kitahama
- 👤 Isamu Iwami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 00:27
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01B21/0685; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C01P; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/10; C01P2004/60; C01P2004/62
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
63 words
A method for the manufacture of silicon nitride having a particle diameter of at most 1.5 microns which comprises subjecting a homogeneous mixture of a liquid silicic acid or a modified liquid silicic acid with carbon in the form of powder or a solution to a heat treatment at a temperature of 1300° C. to 1600° C. in a non-oxidizing atmosphere containing nitrogen.
Claim 2
Independent Claim
63 words
A method for the manufacture of silicon nitride having a particle diameter of at most 1.5 microns which comprises subjecting a homogeneous mixture of a liquid silicic acid or a modified liquid silicic acid with carbon in the form of powder or a solution to a heat treatment at a temperature of 1300° C. to 1600° C. in a non-oxidizing atmosphere containing nitrogen.
Claim 3
Dependent Claim
30 words
A method according to claim 1, wherein the liquid silicic acid is a solution or sol of silicic acid obtained by neutralization or dealkalinization of an aqueous alkali silicate solution.
Claim 4
Dependent Claim
27 words
A method according to claim 1, wherein the liquid silicic acid is a solution or sol of silicic acid obtained by hydrolysis of a hydrolyzable silicon compound.
Claim 5
Dependent Claim
22 words
A method according to claim 1, wherein the carbon in the form of powder is a carbon black or an activated carbon.
Claim 6
Dependent Claim
21 words
A method according to claim 2, wherein the carbon in the form of powder is a carbon black or activated carbon.
Claim 7
Dependent Claim
39 words
A method according to claim 1, wherein the precursor of carbon is a carbohydrate or a derivative thereof, a protein substance or a derivative thereof, a vinyl polymer or a derivative thereof, a thermosetting resin, or a petroleum pitch.
Claim 8
Dependent Claim
39 words
A method according to claim 2, wherein the precursor or carbon is a carbohydrate or a derivative thereof, a protein substance or a derivative thereof, a vinyl polymer or a derivative thereof, a thermosetting resin, or a petroleum pitch.
Claim 9
Dependent Claim
50 words
A method according to claim 1, wherein the precursor of carbon is starch or a hydrolyzate thereof, cellulose, hemi-cellulose, hydroxyethyl cellulose, arginic acid, pectin, natural gum, dextrin, dextran, sucrose, maltose, glucose, gluten, casein, polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polybutadiene, phenol resin, urea resin, or petroleum pitch.
Claim 10
Dependent Claim
23 words
A method accordiang to claim 1, wherein the precursor of carbon is starch, glucose, sucrose, alginic acid, casein, hydroxyethyl cellulose, or polyvinyl alcohol.
Claim 11
Dependent Claim
18 words
A method according to claim 1, wherein the precursor of carbon is a carbohydrate or a derivative thereof.
Claim 12
Dependent Claim
16 words
A method according to claim 1, wherein the precursor of carbon is starch or hydrolyzate thereof.
Claim 13
Independent Claim
78 words
A method for the manufacture of silicon nitride having a particle diameter of at most 1.5 microns which comprises forming a homogeneous mixture of a liquid silicic acid or a modified liquid silicic acid with carbon in the form of a powder or a precursor of carbon in the form of powder or a solution, precipitating the mixture, and heat treating the precipitate at a temperature of 1300° C. to 1600° C. in a non-oxidizing atmosphere containing nitrogen.
Claim 14
Independent Claim
78 words
A method for the manufacture of silicon nitride having a particle diameter of at most 1.5 microns which comprises forming a homogeneous mixture of a liquid silicic acid or a modified liquid silicic acid with carbon in the form of a powder or a precursor of carbon in the form of powder or a solution, precipitating the mixture, and heat treating the precipitate at a temperature of 1300° C. to 1600° C. in a non-oxidizing atmosphere containing nitrogen.
Claim 15
Independent Claim
78 words
A method for the manufacture of silicon nitride having a particle diameter of at most 1.5 microns which comprises forming a homogeneous mixture of a liquid silicic acid or a modified liquid silicic acid with carbon in the form of powder or a precursor of carbon in the form of powder or a solution, drying the mixture, and heat treating the dried mixture at a temperature of 1300° C. to 1600° C. in a non-oxidizing atmosphere containing nitrogen.
Claim 16
Independent Claim
78 words
A method for the manufacture of silicon nitride having a particle diameter of at most 1.5 microns which comprises forming a homogeneous mixture of a liquid silicic acid or a modified liquid silicic acid with carbon in the form of powder or a precursor of carbon in the form of powder or a solution, drying the mixture, and heat treating the dried mixture at a temperature of 1300° C. to 1600° C. in a non-oxidizing atmosphere containing nitrogen.
Claim 17
Dependent Claim
13 words
A method according to claim 13, wherein the drying is performed by spray-drying.
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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) | 1986-08-01 | 1987-01-31 | 1987-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-01 | 1991-01-31 | 1991-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-01 | 1995-01-31 | 1995-08-02 | $7700.00 | Window Closed / Lapsed |