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US5089448A
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Silicon nitride sintered body having excellent high-temperature strength and method of producing same
Assignee: Honda Motor Co Ltd
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Filing: 1990-12-24
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Granted: 1992-02-18
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Expires: 2010-12-24
Abstract
Abstract A silicon nitride sintered body having a composition of 1.5-3.0 weight % of Y 2 O 3 , 0.1-1.0 weight % of Al 2 O 3 and balance substantially Si 3 N 4 , a weight ratio of Y 2 O 3 /Al 2 O 3 being 2.5 or more, which has a density of 3.0 g/cm 3 or more and has a structure in which the minor axes of grains are substantially 6 μm or less. This silicon nitride sintered body is produced by preparing a powder mixture containing Y 2 O 3 powder, Al 2 O 3 powder and silicon nitride powder in the above proportions, the silicon nitride powder having an oxygen content of 1.2 weight % or less, a specific surface area of 9-11 m 2 /g and a metal impurity content of 200 ppm or less; and sintering the powder mixture at a temperature of 1900°-2100° C. and a pressure of 5 kg/cm 2 G or more in a nitrogen atmosphere.
Inventors
- 👤 Yasunobu Kawakami
- 👤 Kagehisa Hamazaki
- 👤 Toshihiko Arakawa
- 👤 Toshiyuki Mori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:50
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/5935
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
124 words
A silicon nitride body having a composition consisting essentially of 2.0-2.8 weight % of Y 2 O 3 , 0.4-1.0 weight % of Al 2 O 3 and balance substantially Si 3 N 4 , the weight ratio of Y 2 O 3 /Al 2 O 3 being 2.5-7, said Si 3 N 4 being added as silicon nitride powder having an oxygen content of 0.8-1.1 weight %, a specific surface area of 9∝11 m 2 /g, and metal impurity content of 200 ppm or less, said sintered body having a density of 3.0 g/cm 3 or more, a structure in which the minor axes of grains are substantially 6 μm or less, and a high-temperature strength of about 80 kg/mm 2 or more.
Claim 2
Dependent Claim
124 words
A silicon nitride body having a composition consisting essentially of 2.0-2.8 weight % of Y 2 O 3 , 0.4-1.0 weight % of Al 2 O 3 and balance substantially Si 3 N 4 , the weight ratio of Y 2 O 3 /Al 2 O 3 being 2.5-7, said Si 3 N 4 being added as silicon nitride powder having an oxygen content of 0.8-1.1 weight %, a specific surface area of 9∝11 m 2 /g, and metal impurity content of 200 ppm or less, said sintered body having a density of 3.0 g/cm 3 or more, a structure in which the minor axes of grains are substantially 6 μm or less, and a high-temperature strength of about 80 kg/mm 2 or more.
Claim 3
Dependent Claim
118 words
The silicon nitride body of claim 1, wherein said composition consists essentially of 2.5 weight % of Y 2 O 3 , 1.0 weight % of Al 2 O 3 and balance substantially Si 3 N 4 , a weight ratio of Y 2 O 3 /Al 2 O 3 of 2.5, said Si 3 N 4 being added as silicon nitride powder having an oxygen content of 0.9 weight %, a specific surface area of 10 m 2 /g, and a metal impurity content of 200 ppm or less, said sintered body having a density of 3.17 g/cm 3 , and having a structure in which the maximum value of minor axes of grains is 5.8 μm.
Claim 4
Dependent Claim
118 words
The silicon nitride body of claim 1, wherein said composition consists essentially of 2.5 weight % of Y 2 O 3 , 0.5 weight % of Al 2 O 3 and balance substantially Si 3 N 4 , a weight ratio of Y 2 O 3 /Al 2 O 3 of 5.0, said Si 3 N 4 being added as silicon nitride powder having an oxygen content of 1.0 weight %, a specific surface are of 10 m 2 /g, and a metal impurity content of 200 ppm or less, said sintered body having a density of 3.18 g/cm 3 , and having a structure in which the maximum value of minor axes of grains are 5.5 μm.
Claim 5
Independent Claim
148 words
A method of producing a silicon nitride sintered body having a structure in which the minor axes of grains are substantially 6 μm or less, comprising the steps of: preparing a powder mixture consisting essentially of 2.0-2.8 weight % of Y 2 O 3 powder, 0.4-1.0 weight % of Al 2 O 3 powder and balance substantially silicon nitride powder, the weight ratio of Y 2 O 3 /Al 2 O 3 being 2.5-7, said silicon nitride powder having an oxygen content of 0.8-1.1 weight %, a specific surface area of 9-11 m 2 /g, and a metal impurity content of 200 ppm or less; and sintering said powder mixture at a temperature of 1900°-2100° C. and a pressure of 5 kg/cm 2 G or more in a nitrogen atmosphere, thereby producing a silicon nitride sintered body exhibiting a high-temperature strength of about 80 kg/mm 2 or more.
Claim 6
Independent Claim
148 words
A method of producing a silicon nitride sintered body having a structure in which the minor axes of grains are substantially 6 μm or less, comprising the steps of: preparing a powder mixture consisting essentially of 2.0-2.8 weight % of Y 2 O 3 powder, 0.4-1.0 weight % of Al 2 O 3 powder and balance substantially silicon nitride powder, the weight ratio of Y 2 O 3 /Al 2 O 3 being 2.5-7, said silicon nitride powder having an oxygen content of 0.8-1.1 weight %, a specific surface area of 9-11 m 2 /g, and a metal impurity content of 200 ppm or less; and sintering said powder mixture at a temperature of 1900°-2100° C. and a pressure of 5 kg/cm 2 G or more in a nitrogen atmosphere, thereby producing a silicon nitride sintered body exhibiting a high-temperature strength of about 80 kg/mm 2 or more.
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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) | 1995-02-17 | 1995-08-19 | 1996-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-17 | 1999-08-19 | 2000-02-18 | $3760.00 | Window Closed / Lapsed |
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