US4920085A
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US
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Silicon nitride sintered body and process for preparation thereof
Assignee: Kyocera Corp
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Filing: 1988-04-01
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Granted: 1990-04-24
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Expires: 2008-04-01
Abstract
Abstract Disclosed is a silicon nitride sintered body comprising 85 to 99 mol % of beta -Si3N4, 1 to 5 mol % as the oxide (M2O3) of at least one compound of an element (M) selected from the group consisting of Sc, Vb, Er, Ho and Dy and less than 10 mol % of excessive oxygen (O2) based on the three components, wherein the excessive oxygen/M2O3 molar ratio is lower than 2.
Inventors
- 👤 Makoto Yoshida
- 👤 Masahiro Sato
- 👤 Kazunori Koga
- 👤 Kazumi Osamura
- 👤 Shoji Kousaka
- 👤 Tatsumi Maeda
- 👤 Kiyoshi Yokoyama
- 👤 Masafumi Matsunaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:31
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/5935
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
158 words
A silicon nitride sintered body comprising 85 to 99 mole % of β-Si 3 N 4 , 1 to 5 mole % of at least one oxide (M 2 O 3 ) of an element (M) selected from the group consisting of Sc, Yb, Er, Ho and Dy and less than 10 mole % of excessive oxygen (O 2 ), in the form of SiO 2 , based on the three components, the excessive oxygen in the form of SiO 2 /M 2 O 3 molar ratio being lower than 2, wherein said body comprises grains of Si 3 N 4 and a grain boundary comprising a vitreous phase and a crystal phase consisting of M 4 Si 2 O 7 N 2 or a major amount of M 4 Si 2 O 7 N 2 and a minor amount of at least one of MSiO 2 N and M 10 Si 7 O 23 N 4 .
Claim 2
Dependent Claim
158 words
A silicon nitride sintered body comprising 85 to 99 mole % of β-Si 3 N 4 , 1 to 5 mole % of at least one oxide (M 2 O 3 ) of an element (M) selected from the group consisting of Sc, Yb, Er, Ho and Dy and less than 10 mole % of excessive oxygen (O 2 ), in the form of SiO 2 , based on the three components, the excessive oxygen in the form of SiO 2 /M 2 O 3 molar ratio being lower than 2, wherein said body comprises grains of Si 3 N 4 and a grain boundary comprising a vitreous phase and a crystal phase consisting of M 4 Si 2 O 7 N 2 or a major amount of M 4 Si 2 O 7 N 2 and a minor amount of at least one of MSiO 2 N and M 10 Si 7 O 23 N 4 .
Claim 3
Dependent Claim
22 words
A silicon nitride sintered body as set forth in claim 1, wherein the grain boundary has a crystallinity of 30 to 90%.
Claim 4
Dependent Claim
120 words
A silicon nitride sintered body comprising 85 to 99 mole % of β-Si 3 N 4 , 1 to 5 mole % of at least one oxide (M 2 O 3 ) of an element (M) selected from the group consisting of Sc, Yb, Er, Ho and Dy and less than 10 mole % of excessive oxygen (O 2 ) in the form of SiO 2 based on the three components, the excessive oxygen in the form of SiO 2 /M 2 O 3 molar ratio being lower than 2, wherein said body comprises grains of Si 3 N 4 and a grain boundary comprising a vitreous phase and a crystal phase comprising a major amount of MSiO 2 N.
Claim 5
Dependent Claim
120 words
A silicon nitride sintered body comprising 85 to 99 mole % of β-Si 3 N 4 , 1 to 5 mole % of at least one oxide (M 2 O 3 ) of an element (M) selected from the group consisting of Sc, Yb, Er, Ho and Dy and less than 10 mole % of excessive oxygen (O 2 ) in the form of SiO 2 based on the three components, the excessive oxygen in the form of SiO 2 /M 2 O 3 molar ratio being lower than 2, wherein said body comprises grains of Si 3 N 4 and a grain boundary comprising a vitreous phase and a crystal phase comprising a major amount of MSiO 2 N.
Claim 6
Dependent Claim
22 words
A silicon nitride sintered body as set forth in claim 3, wherein the grain boundary has a crystallinity of 30 to 90%.
Claim 7
Dependent Claim
62 words
A silicon nitride sintered body as set forth in claim 1, wherein the amount of the compound of the element (M) is 1.5 to 3 mole % as the oxide (M 2 O 3 ), the amount of excessive oxygen (O 2 ) is smaller than 6 mole %, and the excessive oxygen/M 2 O 3 molar ratio is less than 1.8.
Claim 8
Dependent Claim
48 words
A silicon nitride sintered body as set forth in claim 1, wherein the high-temperature flexural strength (1400° C., 4-point bending flexural strength) is at least 45 kg/mm 2 and the weight increase by oxidation at a medium temperature (1000° C.×100 hours) is smaller than 0.2 mg/cm 2 .
Claim 9
Dependent Claim
44 words
A silicon nitride sintered body as set forth in claim 1, wherein a compound of at least one element selected from the group consisting of elements of the group VIa is contained in an amount of 0.1 to 1.5 mole % as the oxide.
Claim 10
Dependent Claim
31 words
A silicon nitride sintered body as set forth in claim 7, wherein the compound of the element of the group VIa of the periodic table is tungsten oxide (WO 3 ).
Claim 11
Dependent Claim
27 words
A silicon nitride sintered body as set forth in claim 1, wherein Al is contained in an amount of up to 1 mole % as the oxide.
Claim 12
Dependent Claim
27 words
A silicon nitride sintered body as set forth in claim 9, wherein Al is contained in an amount of 0.1 to 1 mole % as the oxide.
Claim 13
Dependent Claim
30 words
A silicon nitride sintered body as set forth in claim 1, wherein a compound of Y is contained in an amount of 0.1 to 2.5 mole % as the oxide.
Claim 14
Dependent Claim
74 words
A silicon nitride sintered body as set forth in claim 11, wherein the molar ratio (M 2 O 3 /Y 2 O 3 ) of the amount as the oxide (M 2 O 3 ) of at least one element selected from the group consisting of Sc, Yb, Er, Ho and Dy to the amount as the oxide (Y 2 O 3 ) of Y is in the range of from 0.4 to 50.
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