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Patent US4981823A successfully refreshed from Google Patents.
US4981823A
Expired / Lapsed
US
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Beryllium oxide based ceramics
Assignee: CBL Ceramics Ltd
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Filing: 1988-12-07
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Granted: 1991-01-01
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Expires: 2008-12-07
Abstract
Abstract A ceramic article made from a mixture comprising (on a dry weight basis) magnesium oxide (MgO) in an amount up to 2% by weight, a defined rare earth oxide in amount up to 10% by weight, balance beryllium oxide, and trace elements, the defined rare earth oxide being zirconium oxide (ZrO 2 ), hafnium oxide (HfO 2 ), cerium oxide (Ce 2 O 3 ), yttrium oxide (Y 2 O 3 ), ytterbium oxide (Yb 2 O 3 ) or thorium oxide (ThO 2 ). Such ceramic articles have much improved properties in particular higher densities than attainable hitherto and better crossbreak strength and surface smoothness as fired. The ceramic compositions can also be admixed with supplementary ceramic materials such as silicon carbide to produce microwave absorbing materials.
Inventors
- 👤 Michael Crutchley
- 👤 Ronald Stevens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:32
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/08
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
79 words
A ceramic article having a density of at least 98% of its theoretical density and a Young's modulus (E) of at least 350 GPa, made from a mixture consisting essentially of on a dry weight basis magnesium oxide in an amount from 0.01% to 2% by weight, a defined oxide in an amount from 1% to 9.5% by weight, balance beryllium oxide, the defined oxide being zirconium oxide, hafnium oxide, cerium oxide, yttrium oxide, ytterbium oxide, or thorium oxide.
Claim 2
Dependent Claim
79 words
A ceramic article having a density of at least 98% of its theoretical density and a Young's modulus (E) of at least 350 GPa, made from a mixture consisting essentially of on a dry weight basis magnesium oxide in an amount from 0.01% to 2% by weight, a defined oxide in an amount from 1% to 9.5% by weight, balance beryllium oxide, the defined oxide being zirconium oxide, hafnium oxide, cerium oxide, yttrium oxide, ytterbium oxide, or thorium oxide.
Claim 3
Dependent Claim
89 words
A fired ceramic made by firing a mixture consisting essentially of on a dry weight basis 0.01 to 0.49% by weight magnesium oxide, 1.0 to 9.5% by weight defined oxide less than 0.05% by weight silicon dioxide or silicon compounds, balance beryllium oxide trace, silicon compounds, wherein the defined oxide is an oxide of zirconium, hafnium, cerium, yttrium, ytterbium, or thorium, or a mixture thereof, the fired ceramic having a density of at least 98% of its theoretical density and a Young's modulus (E) of at least 350 GPa.
Claim 4
Dependent Claim
89 words
A fired ceramic made by firing a mixture consisting essentially of on a dry weight basis 0.01 to 0.49% by weight magnesium oxide, 1.0 to 9.5% by weight defined oxide less than 0.05% by weight silicon dioxide or silicon compounds, balance beryllium oxide trace, silicon compounds, wherein the defined oxide is an oxide of zirconium, hafnium, cerium, yttrium, ytterbium, or thorium, or a mixture thereof, the fired ceramic having a density of at least 98% of its theoretical density and a Young's modulus (E) of at least 350 GPa.
Claim 5
Dependent Claim
25 words
A fired ceramic as claimed in claim 1 in which the amount of magnesium oxide is in the range of 0.01 to 0.5% by weight.
Claim 6
Dependent Claim
26 words
A fired ceramic as claimed in claim 1, in which the amount of defined rare earth oxide is in the range 1.7 to 7.0% by weight.
Claim 7
Dependent Claim
26 words
A fired ceramic as claimed in claim 1 or 2 in which the a of magnesium oxide is in the range 0.1 to 0.3% by weight.
Claim 8
Dependent Claim
93 words
A fired ceramic made by firing a mixture consisting essentially of on a dry weight basis 0.01 to 0.49% by weight magnesium oxide, 1.0 to 9.5% by weight defined oxide, less than 0.05% by weight silicon dioxide or silicon compounds, balance beryllium oxide, oxide is an oxide of zirconium, hafnium, cerium, yttrium, ytterbium, or thorium, or a mixture thereof, the fired ceramic having a density of at least 98% of its theoretical density, a Young's modulus (E) of at least 350 GPa, and a surface smoothness as fired of 10 microinches or less.
Claim 9
Dependent Claim
93 words
A fired ceramic made by firing a mixture consisting essentially of on a dry weight basis 0.01 to 0.49% by weight magnesium oxide, 1.0 to 9.5% by weight defined oxide, less than 0.05% by weight silicon dioxide or silicon compounds, balance beryllium oxide, oxide is an oxide of zirconium, hafnium, cerium, yttrium, ytterbium, or thorium, or a mixture thereof, the fired ceramic having a density of at least 98% of its theoretical density, a Young's modulus (E) of at least 350 GPa, and a surface smoothness as fired of 10 microinches or less.
Claim 10
Dependent Claim
100 words
A fired ceramic made by firing a mixture consisting essentially of on a dry weight basis 0.01 to 0.49% by weight magnesium oxide, 1.0 to 9.5% by weight defined oxide, less than 0.05% by weight silicon dioxide or silicon compounds, balance beryllium oxide wherein the defined oxide is an oxide of zirconium, hafnium, cerium, yttrium, ytterbium, or thorium, or a mixture thereof, the fired ceramic having a density of at least 98% of its theoretical density, and a Young's modulus (E) of at least 350 GPA, and wherein said ceramic article has improved hardness and fracture strength (sigma f ).
Claim 11
Dependent Claim
100 words
A fired ceramic made by firing a mixture consisting essentially of on a dry weight basis 0.01 to 0.49% by weight magnesium oxide, 1.0 to 9.5% by weight defined oxide, less than 0.05% by weight silicon dioxide or silicon compounds, balance beryllium oxide wherein the defined oxide is an oxide of zirconium, hafnium, cerium, yttrium, ytterbium, or thorium, or a mixture thereof, the fired ceramic having a density of at least 98% of its theoretical density, and a Young's modulus (E) of at least 350 GPA, and wherein said ceramic article has improved hardness and fracture strength (sigma f ).
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-31 | 1994-07-02 | 1995-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-31 | 1998-07-02 | 1999-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-31 | 2002-07-02 | 2003-01-01 | $7700.00 | Window Closed / Lapsed |