Patent US4134947A successfully refreshed from Google Patents.
US4134947A
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US
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Sintered silicon nitride body and a method of producing the same
Assignee: NGK Insulators Ltd
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Filing: 1976-04-02
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Granted: 1979-01-16
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Expires: 1996-04-02
Abstract
Abstract A sintered silicon nitride body consists of not more than 10% by weight in total of at least two metal oxides selected from the group consisting of beryllium oxide, magnesium oxide and strontium oxide (provided that each of the metal oxides is not more than 5% by weight) and the remainder of silicon nitride and may further contain not more than 10% by weight of at least one rare earth metal oxide, and is produced by preparing a mixture having the said composition range and then molding and sintering it at 1,600°-1,900° C in nitrogen or inert gas atmosphere.
Inventors
- 👤 Isao Oda
- 👤 Masayuki Kaneno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:49
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
123 words
A method of producing a sintered silicon nitride body, comprising preparing a mixture of not more than 10% by weight in total of at least two metal oxides selected from the group consisting of beryllium oxide, magnesium oxide and strontium oxide, provided that each of said metal oxides is not more than 5% by weight, and the remainder being of silicon nitride powder, wherein said silicon nitride powder has an α-phase content of not less than 80% by weight, a purity of not less than 99% and a grain size of not more than 10 μm; molding said mixture into a shaped body and sintering the resulting shaped body at a temperature of 1,600°-1,900° C. in nitrogen or inert gas atmosphere without hot-pressing.
Claim 2
Independent Claim
123 words
A method of producing a sintered silicon nitride body, comprising preparing a mixture of not more than 10% by weight in total of at least two metal oxides selected from the group consisting of beryllium oxide, magnesium oxide and strontium oxide, provided that each of said metal oxides is not more than 5% by weight, and the remainder being of silicon nitride powder, wherein said silicon nitride powder has an α-phase content of not less than 80% by weight, a purity of not less than 99% and a grain size of not more than 10 μm; molding said mixture into a shaped body and sintering the resulting shaped body at a temperature of 1,600°-1,900° C. in nitrogen or inert gas atmosphere without hot-pressing.
Claim 3
Dependent Claim
32 words
A method as claimed in claim 1, wherein the total amount of said metal oxide is 0.2-10% by weight and the amount of each of said metal oxides is 0.1-5% by weight.
Claim 4
Dependent Claim
26 words
A method as claimed in claim 1, wherein said mixture further contains not more than 10% by weight of at least one rare earth metal oxide.
Claim 5
Dependent Claim
20 words
A method as claimed in claim 3, wherein the amount of said rare earth metal oxide is 1-10% by weight.
Claim 6
Dependent Claim
41 words
A method as claimed in claim 3, wherein said rare earth metal oxide is selected from the group consisting of cerium oxide, yttrium oxide, lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, gadolinium oxide, dysprosium oxide, holmium oxide and erbium oxide.
Claim 7
Dependent Claim
20 words
A method as claimed in claim 1, wherein said at least two metal oxides are beryllium oxide and magnesium oxide.
Claim 8
Dependent Claim
20 words
A method as claimed in claim 1, wherein said at least two metal oxides are beryllium oxide and strontium oxide.
Claim 9
Dependent Claim
22 words
A method as claimed in claim 1, wherein said at least two metal oxides are beryllium oxide, magnesium oxide and strontium oxide.
Claim 10
Dependent Claim
25 words
A method as claimed in claim 1, wherein from 1 to 7% by weight in total of said at least two metal oxides are present.
Claim 11
Dependent Claim
22 words
A method as claimed in claim 5, wherein the amount of said rare earth metal oxide is 1 to 5% by weight.
References Cited (Backward Citations)
US3549402A
Cited
GB1340696A
Cited
GB1376891A
Cited
US3950464A
Cited
US3992497A
Cited
US4073845A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-01-15 | 1982-07-17 | 1983-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-01-15 | 1986-07-17 | 1987-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-01-15 | 1990-07-17 | 1991-01-16 | $7700.00 | Window Closed / Lapsed |