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US4238434A
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Method of producing a silicon carbide sintered body
Assignee: Ibigawa Electric Industry Co Ltd
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Filing: 1979-02-02
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Granted: 1980-12-09
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Expires: 1999-02-02
Abstract
Abstract A method of producing a silicon carbide sintered body is disclosed. The sintered body having a density of at least 2.4 g/cm 3 is produced by preparing a mixture consisting mainly of silicon carbide with an average particle size of not more than 3.0 microns and a temporary binder, shaping the mixture into a green body and sintering the green body at a temperature of 1,750° C.-2,100° C. Before the sintering, silicon carbide is contacted with either hydrofluoric acid or anhydrous hydrofluoric acid and an atmosphere is held in a non-oxidizing state after the contact treatment up to the completion of the sintering.
Inventors
- 👤 Ryo Enomoto
- 👤 Hiroyuki Tanaka
- 👤 Kazuhisa Hara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:06
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
142 words
A method of producing a silicon carbide sintered body comprising the steps of: (a) preparing a mixture consisting mainly of silicon carbide having an average particle size of not more than 3 microns and 0.5-10.0 parts by weight as a solid content of a temporary binder based on 100 parts by weight of silicon carbide, (b) shaping the mixture into a green body, and (c) sintering the green body at a temperature of 1,750° C.-2,100° C. to produce a sintered body having a density of at least 2.4 g/cm 3 ; said silicon carbide being contacted with either hydrofluoric acid or anhydrous hydrofluoric acid at latest before the step (c) to remove silicon dioxide film contained thereon and maintained in a non-oxidizing atmosphere after the contact treatment up to the completion of the sintering to prevent formation of silicon dioxide film thereon.
Claim 2
Independent Claim
142 words
A method of producing a silicon carbide sintered body comprising the steps of: (a) preparing a mixture consisting mainly of silicon carbide having an average particle size of not more than 3 microns and 0.5-10.0 parts by weight as a solid content of a temporary binder based on 100 parts by weight of silicon carbide, (b) shaping the mixture into a green body, and (c) sintering the green body at a temperature of 1,750° C.-2,100° C. to produce a sintered body having a density of at least 2.4 g/cm 3 ; said silicon carbide being contacted with either hydrofluoric acid or anhydrous hydrofluoric acid at latest before the step (c) to remove silicon dioxide film contained thereon and maintained in a non-oxidizing atmosphere after the contact treatment up to the completion of the sintering to prevent formation of silicon dioxide film thereon.
Claim 3
Dependent Claim
31 words
A method as claimed in claim 1, wherein said hydrofluoric acid or anhydrous hydrofluoric acid is contacted with said silicon carbide before the preparation of the mixture at the step (a).
Claim 4
Dependent Claim
24 words
A method as claimed in claim 1, wherein said hydrofluoric acid or anhydrous hydrofluoric acid is contacted with said mixture after the step (a).
Claim 5
Dependent Claim
25 words
A method as claimed in claim 1, wherein said hydrofluoric acid or anhydrous hydrofluoric acid is contacted with said green body after the step (b).
Claim 6
Dependent Claim
40 words
A method as claimed in claim 1, wherein said hydrofluoric acid or anhydrous hydrofluoric acid is used in an amount corresponding to at least 0.2 part by weight of hydrogen fluoride based on 100 parts by weight of silicon carbide.
Claim 7
Dependent Claim
37 words
A method as claimed in claim 1, wherein said non-oxidizing atmosphere is at least one gas atmosphere selected from the group consisting of argon, helium, neon, nitrogen, hydrogen, carbon monoxide and anhydrous hydrofluoric acid or a vacuum.
Claim 8
Dependent Claim
51 words
A method as claimed in claim 1, wherein said silicon carbide, mixture or green body contacted with hydrofluoric acid or anhydrous hydrofluoric acid is placed in a container under a non-oxidizing atmosphere and the container is sealed for transfer of the contacted silicon carbide, mixture or green body from said atmosphere.
Claim 9
Dependent Claim
36 words
A method as claimed in claim 7, wherein said container is selected from the group consisting of a rubber bag, a vinyl bag, a plastic vessel, a metal vessel, a glass vessel and a ceramic vessel.
Claim 10
Dependent Claim
38 words
A method as claimed in claim 1, wherein said temporary binder is at least one substance selected from inorganic and organic substances capable of temporarily developing an adhesion between particles of silicon carbide at an initial sintering stage.
Claim 11
Dependent Claim
22 words
A method as claimed in claim 9, wherein said temporary binder is an organic substance soluble in water or an organic solvent.
Claim 12
Dependent Claim
23 words
A method as claimed in claim 1, wherein said mixture contains 1.0-7.0 parts by weight as a solid content of the temporary binder.
Claim 13
Dependent Claim
21 words
A method as claimed in claim 1, wherein said average particle size of silicon carbide is not more than 1.0 micron.
Claim 14
Dependent Claim
23 words
A method as claimed in claim 1, wherein said mixture further contains not more than 5.0 parts by weight of a sintering aid.
Claim 15
Dependent Claim
30 words
A method as claimed in claim 13, wherein said sinterig aid is at least one substance selected from the group consisting of boron, aluminum, iron, tungsten, magnesium and compounds thereof.
Claim 16
Dependent Claim
24 words
A method as claimed in claim 1, wherein said green body is sintered at a temperature of 1,800° C.-2,000° C. at the step (c).
Claim 17
Dependent Claim
21 words
A method as claimed in claim 1, wherein said sintered body has a density of at least 2.9 g/cm 3 .
Claim 18
Dependent Claim
23 words
A method as claimed in claim 1, wherein said green body is directly sintered without subjecting to a presintering at the step (c).
Claim 19
Dependent Claim
23 words
A method as claimed in claim 1, wherein said green body is presintered and worked into a desired shape before the step (c).
Claim 20
Dependent Claim
21 words
A method as claimed in claim 18, wherein said worked body is contacted with either hydrofluoric acid or anhydrous hydrofluoric acid.
Claim 21
Dependent Claim
19 words
A method as claimed in claim 18, wherein said presintering is effected at a temperature of 1,550° C.-1,800° 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) | 1983-12-09 | 1984-06-09 | 1984-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-09 | 1988-06-09 | 1988-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-09 | 1992-06-09 | 1992-12-09 | $7700.00 | Window Closed / Lapsed |