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US4818733A
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Silicon nitride sintered bodies and a method of producing the same
Assignee: NGK Insulators Ltd
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Filing: 1987-03-23
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Granted: 1989-04-04
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Expires: 2007-03-23
Abstract
Abstract A silicon nitride sintered body having high oxidation resistance and high-temperature strength is produced by starting from silicon nitride powder adjusted so as to have an oxygen content of 4.5-7.5 wt % as converted into SiO 2 . The sintered body has a molar ratio of metal ion (M) to oxygen ion (O) within a range of M:O=1.2˜1:3 and contains no crystal of YSiO 2 N form.
Inventors
- 👤 Masahiro Shirai
- 👤 Tomonori Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:24
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
88 words
A silicon nitride sintered body produced by using a sintering aid containing Y as an essential component, added to at least about 80 wt. % silicon nitride powder, said sintered body having a molar ratio of metal ions (M), other than Si ions, contained in the sintered body to oxygen ions (O) contained in the sintered body within a range of M:O=1:2˜1:3, and containing substantially no crystalline phase of a YSiO 2 N form, said phase being identified by an X-ray diffraction pattern according to JCPDS Card 31-1462.
Claim 2
Dependent Claim
88 words
A silicon nitride sintered body produced by using a sintering aid containing Y as an essential component, added to at least about 80 wt. % silicon nitride powder, said sintered body having a molar ratio of metal ions (M), other than Si ions, contained in the sintered body to oxygen ions (O) contained in the sintered body within a range of M:O=1:2˜1:3, and containing substantially no crystalline phase of a YSiO 2 N form, said phase being identified by an X-ray diffraction pattern according to JCPDS Card 31-1462.
Claim 3
Dependent Claim
16 words
A silicon nitride sintered body according to claim 1, wherein said sintering aid further contains Mg.
Claim 4
Dependent Claim
18 words
A silicon nitride sintered body according to claim 1, wherein said sintering aid further contains Mg and Ce.
Claim 5
Independent Claim
142 words
A method of producing silicon nitride sintered bodies, comprising the steps of: (a) preparing a powdery mixture of at least about 80 wt. % silicon nitride powder adjusted so as to have an oxygen content of 4.5-7.5% by weight as converted into SiO 2 and a sintering aid consisting essentially of Y as an essential component; (b) molding the powdery mixture into a shaped body; and (c) firing the shaped body in a nitrogen of inert gas atmosphere to form a silicon nitride sintered body having a molar ratio of metal ions (M), other than Si ions, contained in the sintered body to oxygen ions (O) contained in the sintered body within a range of M:O=1:2˜1:3 and containing substantially no crystalline phase of a YSiO 2 N form, said phase being identified by an X-ray diffraction pattern according to JCPDS Card 31-1462.
Claim 6
Independent Claim
142 words
A method of producing silicon nitride sintered bodies, comprising the steps of: (a) preparing a powdery mixture of at least about 80 wt. % silicon nitride powder adjusted so as to have an oxygen content of 4.5-7.5% by weight as converted into SiO 2 and a sintering aid consisting essentially of Y as an essential component; (b) molding the powdery mixture into a shaped body; and (c) firing the shaped body in a nitrogen of inert gas atmosphere to form a silicon nitride sintered body having a molar ratio of metal ions (M), other than Si ions, contained in the sintered body to oxygen ions (O) contained in the sintered body within a range of M:O=1:2˜1:3 and containing substantially no crystalline phase of a YSiO 2 N form, said phase being identified by an X-ray diffraction pattern according to JCPDS Card 31-1462.
Claim 7
Dependent Claim
37 words
A method according to claim 4, wherein said preparing step is performed by calcining a starting silicon nitride powder in air at a temperature of 800°-1200° C. and wet pulverizing said powder together with said sintering aid.
Claim 8
Dependent Claim
37 words
A method according to claim 4, wherein said preparing step is performed by mixing a starting silicon nitride powder with said sintering aid and then calcining the resulting mixture in air at a temperature of 800°-1200° C.
Claim 9
Dependent Claim
40 words
A method according to claim 4, wherein said preparing step is performed by wet pulverizing a starting silicon nitride powder together with said sintering aid to form a slurry and warming the resulting slurry at a temperature of 50°-150° C.
Claim 10
Dependent Claim
47 words
A method according to claim 4, wherein said preparing step is performed out by wet pulverizing a starting silicon nitride powder with water to form a slurry, warming the resulting slurry at a temperature of 50°-150° C. and then mixing the warmed slurry with said sintering aid.
Claim 11
Dependent Claim
13 words
A method according to claim 4, wherein said sintering aid further contains Mg.
Claim 12
Dependent Claim
15 words
A method according to claim 4, wherein said sintering aid further contains Mg and Ce.
Claim 13
Dependent Claim
20 words
A silicon nitride powder starting material comprising an oxygen content of 4.5-7.5% by weight as converted into SiO 2 .
Claim 14
Dependent Claim
20 words
A silicon nitride powder starting material comprising an oxygen content of 4.5-7.5% by weight as converted into SiO 2 .
Claim 15
Dependent Claim
21 words
A silicon nitride powder starting material according to claim 11, wherein said powder contains an SiO 2 layer on its surface.
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