Patent US4511525A successfully refreshed from Google Patents.
US4511525A
Expired / Lapsed
US
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Process for producing sintered silicon nitride-base body
Assignee: Toshiba Corp
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Filing: 1982-11-22
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Granted: 1985-04-16
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Expires: 2002-11-22
Abstract
Abstract Disclosed is a process for producing a sintered silicon nitride-base body, which comprises; mixing powder (A) of heat-treated or not heat-treated silicon nitride powder and powder (B) of powder obtained by heat-treating a powdery mixture of silicon nitride powder and a sintering additive in a non-oxidizing atmosphere and then grinding the resulting heat-treated products into powder; and forming the resultant powdery mixture into a desired shape, which is then sintered in a non-oxidizing atmosphere. The process is characterized by heating powder (B), or powder (A) and powder (B), before sintering, thereby producing sintered silicon nitride body of highly improved properties.
Inventors
- 👤 Akihiko Tsuge
- 👤 Michiyasu Komatsu
- 👤 Hiroshi Inoue
- 👤 Katsutoshi Komeya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:51
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/597; C04B35/584
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
113 words
A process for producing a sintered silicon nitride-base body, comprising the steps of: producing a powdery mixture (B) comprising silicon nitride and a sintering additive; heat treating said powdery mixture (B) at a temperature ranging from about 1450° to 1750° C. in a non-oxidizing atmosphere; grinding said heat-treated mixture into a powder; heat treating a powder (A) consisting essentially of silicon nitride at a temperature ranging from about 1450° to 1800° C. in a non-oxidizing atmosphere; mixing said heat-treated powdery mixture (B) and said heat-treated powder (A) to form a product powdery mixture; forming said product powdery mixture into a desired shape; and sintering said formed product powdery mixture in a non-oxidizing atmosphere.
Claim 2
Dependent Claim
113 words
A process for producing a sintered silicon nitride-base body, comprising the steps of: producing a powdery mixture (B) comprising silicon nitride and a sintering additive; heat treating said powdery mixture (B) at a temperature ranging from about 1450° to 1750° C. in a non-oxidizing atmosphere; grinding said heat-treated mixture into a powder; heat treating a powder (A) consisting essentially of silicon nitride at a temperature ranging from about 1450° to 1800° C. in a non-oxidizing atmosphere; mixing said heat-treated powdery mixture (B) and said heat-treated powder (A) to form a product powdery mixture; forming said product powdery mixture into a desired shape; and sintering said formed product powdery mixture in a non-oxidizing atmosphere.
Claim 3
Dependent Claim
19 words
The process as claimed in claim 1, wherein the heat-treatment was effected at temperatures of 1500° to 1700° C.
Claim 4
Dependent Claim
29 words
The process as claimed in claim 1, wherein the powder (B) comprises 20 to less than 100 wt.% of the sintering additive and the balance of silicon nitride powder.
Claim 5
Dependent Claim
28 words
The process as claimed in claim 3, wherein the powder (B) consists of 40 to 60 wt.% of the sintering additive and the balance of silicon nitride powder.
Claim 6
Dependent Claim
90 words
The process as claimed in claim 1, wherein the sintering additive comprises one or more compounds selected from the group consisting of MgO, Al 2 O 3 , Y 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , Li 2 O, CaO, BeO, V 2 O 5 , MnO 2 , MoO 3 , WO 3 , Cr 2 O 3 , NiO, Nb 2 O 5 , Ta 2 O 5 , HfO 2 , oxides of other rare earth elements, AlN, TiN and SiC.
Claim 7
Dependent Claim
30 words
The process as claimed in claim 1, wherein the powder (A) is used in a proportion of 75 to less than 100 wt.% and the balance is the powder (B).
Claim 8
Dependent Claim
20 words
The process as claimed in claim 1, wherein the powder (A) is heat-treated at temperatures of 1500° to 1700° C.
References Cited (Backward Citations)
US4004937A
Cited
US4143107A
Cited
US4296065A
Cited
US4073845A
Cited
US4284432A
Cited
US4179301A
Cited
US4327187A
Cited
US4356136A
Cited
US4376742A
Cited
EP0071997A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-04-15 | 1988-10-15 | 1989-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-15 | 1992-10-15 | 1993-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-15 | 1996-10-15 | 1997-04-16 | $7700.00 | Window Closed / Lapsed |