US4960734A
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US
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Ceramic composite and process for preparation thereof
Assignee: Nippon Steel Corp
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Filing: 1989-07-05
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Granted: 1990-10-02
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Expires: 2009-07-05
Abstract
Abstract Disclosed is a ceramic composite consisting essentially of hexagonal boron nitride (h-BN), aluminum nitride and, if any, unavoidably formed aluminum oxynitride (AlON), and a sintering aid and/or a reaction product of the sintering aid with the above-mentioned components (h-BN, AlN and AlON), in which the total amount of the sintering aid and the reaction product is 0.01 to 5 parts by weight per 100 parts by weight of the sum of h-BN, AlN and AlON. This sintered body comprises AlN and AlON in a total amount of 45 to 5% by weight with 55 to 95% by weight of h-BN. Alternatively, this sintered body comprises AlN and AlON in a total amount of 80 to 5% by weight with 20 to 95% by weight of h-BN, the degree of anisotropy of the thermal conductivity of the sintered body (the ratio of the maximum thermal conductivity to the minimum thermal conductivity, the direction of the maximum thermal conductivity being perpendicular to the direction of the minimum thermal conductivity) being at least 2.
Inventors
- 👤 Takao Kanai
- 👤 Kei Tanemoto
- 👤 Hiroshi Kubo
- 👤 Toyohiko Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:10
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/581; C04B35/583
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
142 words
A ceramic sintered body consisting essentially of hexagonal boron nitride (h-BN), aluminum nitride (AlN) and unavoidably formed aluminum oxynitride (AlON) if any, and a sintering aid and/or a reaction product of the sintering aid with said h-BN, AlN and AlON, the total amount of the sintering aid and the reaction product being 0.01 to 5 parts by weight per 100 parts by weight of the sum of h-BN, AlN, and AlON, wherein the sintered body comprises AlN and AlON in a total amount of 5 to 80% by weight with 20 to 95% by weight of h-BN having an average grain size of at least 1 μm, a degree of anisotropy of the thermal conductivity of the sintered body being at least 2, and wherein the direction of the maximum thermal conductivity is perpendicular to the direction of the minimum thermal conductivity.
Claim 2
Dependent Claim
142 words
A ceramic sintered body consisting essentially of hexagonal boron nitride (h-BN), aluminum nitride (AlN) and unavoidably formed aluminum oxynitride (AlON) if any, and a sintering aid and/or a reaction product of the sintering aid with said h-BN, AlN and AlON, the total amount of the sintering aid and the reaction product being 0.01 to 5 parts by weight per 100 parts by weight of the sum of h-BN, AlN, and AlON, wherein the sintered body comprises AlN and AlON in a total amount of 5 to 80% by weight with 20 to 95% by weight of h-BN having an average grain size of at least 1 μm, a degree of anisotropy of the thermal conductivity of the sintered body being at least 2, and wherein the direction of the maximum thermal conductivity is perpendicular to the direction of the minimum thermal conductivity.
Claim 3
Dependent Claim
72 words
A ceramic sintered body set forth in claim 1, wherein the sintered body comprises AlN and, if any, AlON in a total amount of 80 to 20% by weight with 20 to 80% by weight of h-BN, the degree of anisotropy of the thermal conductivity of the sintered body is at least 2, and, the sintered body has a maximum thermal conductivity of at least 150 W/m.K in at least one direction.
Claim 4
Dependent Claim
37 words
A ceramic composite as set forth in claim 2, wherein the sintered body comprises AlN and, if any, AlON in a total amount of 75 to 50% by weight with 25 to 50% by weight of h-BN.
Claim 5
Dependent Claim
37 words
A ceramic composite as set forth in claim 2, wherein the sintered body comprises AlN and, if any, AlON in a total amount of 50 to 25% by weight with 50 to 75% by weight of h-BN.
Claim 6
Dependent Claim
21 words
A ceramic composite as set forth in claim 1, wherein the grain size of h-BN is 5 μm to 30 μm.
Claim 7
Dependent Claim
49 words
A ceramic composite as set forth in claim 2, wherein the sintering aid and the reaction product of the sintering aid are present in a total amount of 0.2 to 5.0 parts by weight per 100 parts by weight of the sum of h-BN, AlN, and, if any, AlON.
Claim 8
Dependent Claim
97 words
A ceramic sintered body consisting essentially of hexagonal boron nitride (h-BN), aluminum nitride (AlN) and unavoidably formed aluminum oxynitride (AlON) if any, and a sintering aid and/or a reaction product of the sintering aid with said h-BN, AlN and AlON, the total amount of the sintering aid and the reaction product being 0.01 to 5 parts by weight per 100 parts by weight of the sum of h-BN, AlN, and AlON, wherein the sintered body comprises AlN and AlON in a total amount of 5 to 45% by weight with 55 to 95% by weight of h-BN.
Claim 9
Dependent Claim
97 words
A ceramic sintered body consisting essentially of hexagonal boron nitride (h-BN), aluminum nitride (AlN) and unavoidably formed aluminum oxynitride (AlON) if any, and a sintering aid and/or a reaction product of the sintering aid with said h-BN, AlN and AlON, the total amount of the sintering aid and the reaction product being 0.01 to 5 parts by weight per 100 parts by weight of the sum of h-BN, AlN, and AlON, wherein the sintered body comprises AlN and AlON in a total amount of 5 to 45% by weight with 55 to 95% by weight of h-BN.
Claim 10
Dependent Claim
29 words
A ceramic composite as set forth in claim 7, wherein the sintering aid is at least one compound selected from the group consisting of calcium compounds and yttrium compounds.
Claim 11
Dependent Claim
41 words
A ceramic composite as set forth in claim 7, wherein the reaction product of the sintering aid with the h-BN, AlN and AlON components is composed mainly of a compound selected from the group consisting of calcium aluminates and yttrium aluminates.
Claim 12
Dependent Claim
78 words
A ceramic sintered body as set forth in claim 7, wherein the sintered body has a maximum thermal conductivity at room temperature of at least 40 W/m.K, an average thermal expansion coefficient in a range of from 0° to 400° C. of 1.0 to 4.0×10 -6 /K, a dielectric constant at room temperature and 1 MHz of smaller than 7.5, a porosity of lower than 15% and a flexural strength at room temperature of at least 40 MPa.
Claim 13
Dependent Claim
53 words
A ceramic composite as set forth in claim 10, wherein the sintering aid and the reaction product of the sintering aid with H-BN, AlN and AlON components are present in a total amount of 0.2 to 5.0 parts by weight per 100 parts by weight of the sum of h-BN, AlN, and AlON.
Claim 14
Dependent Claim
41 words
A ceramic sintered body as set in claim 7, wherein the sintered body comprises a total amount of 40% by weight to 10% by weight of AlN and, if present, AlON, and 60% by weight to 90% by weight of h-BN.
Claim 15
Dependent Claim
86 words
A process for the preparation of a ceramic composite, which comprises adding a sintering aid in an amount of up to 10 parts by weight to 100 parts by weight of a powder comprising 55 to 95 parts by weight of a powder of hexagonal boron nitride (h-BN) and 5 to 45 parts by weight of a powder of aluminum nitride (AlN), and heating under pressure the resultant mixture in an inert gas flow under conditions of 1500° to 2000° C. and 5 to 100 MPa.
Claim 16
Dependent Claim
86 words
A process for the preparation of a ceramic composite, which comprises adding a sintering aid in an amount of up to 10 parts by weight to 100 parts by weight of a powder comprising 55 to 95 parts by weight of a powder of hexagonal boron nitride (h-BN) and 5 to 45 parts by weight of a powder of aluminum nitride (AlN), and heating under pressure the resultant mixture in an inert gas flow under conditions of 1500° to 2000° C. and 5 to 100 MPa.
Claim 17
Dependent Claim
48 words
A process according to claim 13, wherein a compounds selected from the group consisting of calcium compounds and yttrium compounds is used as the sintering aid in an amount of up to 5 parts by weight per 100 parts by weight of the sum of h-BN and AlN.
Claim 18
Dependent Claim
48 words
A process according to claim 14, wherein a compound selected from the group consisting of calcium compounds and yttrium compounds is used as the sintering aid in an amount of 0.2 to 5.0 parts by weight per 100 parts by weight of the sum of h-BN and AlN.
Claim 19
Dependent Claim
27 words
A process according to claim 14, wherein anhydrous boron oxide is further added as the sintering aid in an amount of 0.1 to 5 parts by weight.
Claim 20
Dependent Claim
34 words
A process according to claim 14, wherein the calcium compound is selected from the group consisting of calcium oxide, calcium carbide, calcium carbonate, calcium nitrate, calcium fluoride, calcium hydroxide, calcium cyanide and calcium cyanamide.
Claim 21
Dependent Claim
26 words
A process according to claim 14, wherein the yttrium compound is selected from the group consisting of yttrium oxide, yttrium carbide, yttrium fluoride and yttrium nitrate.
Claim 22
Dependent Claim
16 words
A process according to claim 13, wherein the inert gas flow is a nitrogen gas flow.
Claim 23
Dependent Claim
37 words
A process according to claim 13, wherein the sintered body formed by the heating under pressure is further heat-treated at a temperature of 1300° to 1500° C. in a reducing atmosphere or in an inert gas flow.
Claim 24
Dependent Claim
23 words
A process according to claim 20, wherein the heat treatment is carried out at 1300° to 1500° C. for 0.5 to 2 hours.
Claim 25
Dependent Claim
32 words
A process according to claim 13, wherein the sintered body formed by the heating under pressure is further heat-treated at a temperature of 1800° to 2000° C. for at least 2 hours.
Claim 26
Dependent Claim
37 words
A process according to claim 13, wherein the sintered body formed by the heating under pressure is further heat-treated at a temperature of 1800° to 2000° C. in a reducing atmosphere or in an inert gas flow.
Claim 27
Dependent Claim
83 words
A process for the preparation of a ceramic sintered body, which comprises adding a sintering aid in an amount of up to 10 parts by weight to 100 parts by weight of a powder comprising 60-90 parts by weight of a powder of hexagonal boron nitride (h-BN) and 40-10 parts by weight of a powder of aluminum nitride (AlN), and heating under pressure the resultant mixture in an inert gas flow under conditions of 1500° to 2000° C. and 5 to 100 MPa.
Claim 28
Dependent Claim
83 words
A process for the preparation of a ceramic sintered body, which comprises adding a sintering aid in an amount of up to 10 parts by weight to 100 parts by weight of a powder comprising 60-90 parts by weight of a powder of hexagonal boron nitride (h-BN) and 40-10 parts by weight of a powder of aluminum nitride (AlN), and heating under pressure the resultant mixture in an inert gas flow under conditions of 1500° to 2000° C. and 5 to 100 MPa.
References Cited (Backward Citations)
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) | 1993-10-01 | 1994-04-02 | 1994-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-01 | 1998-04-02 | 1998-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-01 | 2002-04-02 | 2002-10-02 | $7700.00 | Window Closed / Lapsed |