US4965231A
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Alumina-zirconia-silicon carbide-magnesia compositions and articles made therefrom
Assignee: Kennametal PC Inc
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Filing: 1988-11-03
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Granted: 1990-10-23
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Expires: 2008-11-03
Abstract
Abstract An alumina based ceramic composition is provided containing (in volume percent, v/o): about 1.5 to 17.5 silicon carbide whiskers; about 5 to 17.5 zirconia; residue of a magnesium oxide addition added in an amount of about 0.03 to 3; and an alumina based matrix in which the silicon carbide whiskers, zirconia and residue of magnesium oxide are substantially homogeneously distributed. At least 4 v/o of the alumina based ceramic composition is tetragonal zirconia.
Inventors
- 👤 Pankaj K. Mehrotra
- 👤 Elizabeth R. Billman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:58
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/117; C04B35/119; C04B35/622; C04B35/64; C04B35/645; C04B35/71; C04B35/78; C04B35/80
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
85 words
An alumina based ceramic composition consisting essentially of: about 1.5 to 17.5 v/o silicon carbide whiskers; about 5 to 17.5 v/o zirconia; a residue of a magnesia addition added in the amount of about 0.03 to 3 v/o; alumina forming essentially the remainder of said composition; wherein said silicon carbide whiskers, said zirconia and said residue of said magnesia addition are substantially homogeneously dispersed in a matrix formed of said alumina; and wherein at least about 4.0 v/o of said ceramic composition is tetragonal zirconia.
Claim 2
Dependent Claim
85 words
An alumina based ceramic composition consisting essentially of: about 1.5 to 17.5 v/o silicon carbide whiskers; about 5 to 17.5 v/o zirconia; a residue of a magnesia addition added in the amount of about 0.03 to 3 v/o; alumina forming essentially the remainder of said composition; wherein said silicon carbide whiskers, said zirconia and said residue of said magnesia addition are substantially homogeneously dispersed in a matrix formed of said alumina; and wherein at least about 4.0 v/o of said ceramic composition is tetragonal zirconia.
Claim 3
Dependent Claim
21 words
The alumina based ceramic composition according to claim 1 wherein at least about 6.0 v/o of said composition is tetragonal zirconia.
Claim 4
Dependent Claim
20 words
The alumina based ceramic composition according to claim 2 wherein said silicon carbide whiskers are about 1.5 to 2.5 v/o.
Claim 5
Dependent Claim
20 words
The alumina based ceramic composition according to claim 1 wherein at least 7 v/o of said composition is tetragonal zirconia.
Claim 6
Dependent Claim
20 words
The alumina based ceramic composition according to claim 3 wherein said silicon carbide whiskers are about 1.5 to 2.5 v/o.
Claim 7
Dependent Claim
22 words
The alumina based ceramic composition according to claim 1 wherein said residue of said magnesia addition is about 0.03 to 2 v/o.
Claim 8
Dependent Claim
22 words
The alumina based ceramic composition according to claim 1 wherein said residue of said magnesia addition is about 0.04 to 1 v/o.
Claim 9
Dependent Claim
20 words
The alumina based ceramic composition according to claim 5 wherein said silicon carbide whiskers are about 1.5 to 2.5 v/o.
Claim 10
Dependent Claim
20 words
The alumina based ceramic composition according to claim 1 wherein said silicon carbide whiskers are about 2.5 to 15 v/o.
Claim 11
Dependent Claim
20 words
The alumina based ceramic composition according to claim 1 wherein said silicon carbide whiskers are about 2.5 to 10.5 v/o.
Claim 12
Dependent Claim
17 words
The alumina based ceramic composition according to claim 1 wherein zirconia is about 7.5 to 17.5 v/o.
Claim 13
Dependent Claim
17 words
The alumina based ceramic composition according to claim 1 wherein zirconia is about 10 to 15 v/o.
Claim 14
Dependent Claim
20 words
The alumina based ceramic composition according to claim 9 wherein said silicon carbide whiskers are about 1.5 to 2.5 v/o.
Claim 15
Dependent Claim
22 words
The alumina based ceramic composition according to claim 1 wherein said zirconia has an average particle size of less than 2 microns.
Claim 16
Dependent Claim
25 words
The alumina based ceramic composition according to claim 1 wherein said zirconia has an average particle size of less than or equal to one micron.
Claim 17
Dependent Claim
20 words
The alumina based ceramic composition according to claim 1 wherein said silicon carbide whiskers are about 1.5 to 2.5 v/o.
Claim 18
Dependent Claim
115 words
An article of manufacture comprising: an alumina based ceramic composition having a K IC (E&C) toughness of at least about 5MPam1/2; a Rockwell A hardness of at least 93 and a density of at least 98 percent of theoretical; said alumina based ceramic composition consisting essentially of: about 1.5-17.5 v/o silicon carbide whiskers; about 5 to 17.5 v/o ZrO 2 ; a residue of a magnesia addition added in an amount of about 0.03 to 3 v/o; an alumina based matrix wherein said silicon carbide whiskers, said zirconia and said residue of said magnesium oxide addition are substantially homogeneously distributed; and wherein tetragonal zirconia forms at least 4 v/o of said alumina based ceramic composition.
Claim 19
Dependent Claim
115 words
An article of manufacture comprising: an alumina based ceramic composition having a K IC (E&C) toughness of at least about 5MPam1/2; a Rockwell A hardness of at least 93 and a density of at least 98 percent of theoretical; said alumina based ceramic composition consisting essentially of: about 1.5-17.5 v/o silicon carbide whiskers; about 5 to 17.5 v/o ZrO 2 ; a residue of a magnesia addition added in an amount of about 0.03 to 3 v/o; an alumina based matrix wherein said silicon carbide whiskers, said zirconia and said residue of said magnesium oxide addition are substantially homogeneously distributed; and wherein tetragonal zirconia forms at least 4 v/o of said alumina based ceramic composition.
Claim 20
Dependent Claim
18 words
The alumina based ceramic composition according to claim 12 wherein said tetragonal zirconia is at least 6 v/o.
Claim 21
Dependent Claim
18 words
The alumina based ceramic composition according to claim 12 wherein said tetragonal zirconia is at least 7 v/o.
Claim 22
Dependent Claim
18 words
The alumina based ceramic composition according to claim 12 wherein said tetragonal zirconia is at least 8 v/o.
Claim 23
Dependent Claim
20 words
The alumina based ceramic composition according to claim 17 wherein said alumina based matrix is entirely alumina except for impurities.
Claim 24
Dependent Claim
22 words
The alumina based ceramic composition according to claim 17 wherein said zirconia has an average particle size no greater than 5 μm.
Claim 25
Dependent Claim
22 words
The alumina based ceramic composition according to claim 17 wherein said zirconia has an average particle size of less tan 2 μm.
Claim 26
Dependent Claim
115 words
An article of manufacture comprising: an alumina based ceramic composition having a K IC (E&C) toughness of at least about 5MPam1/2; a Rockwell A hardness of at least 93 and a density of at least 98 percent of theoretical; said alumina based ceramic composition consisting essentially of: about 1.5-2.5 v/o silicon carbide whiskers; about 5 to 17.5 v/o ZrO 2 ; a residue of a magnesia addition added in an amount of about 0.03 to 3 v/o; an alumina based matrix wherein said silicon carbide whiskers, said zirconia and said residue of said magnesium oxide addition are substantially homogeneously distributed; and wherein tetragonal zirconia forms at least 4 v/o of said alumina based ceramic composition.
Claim 27
Dependent Claim
115 words
An article of manufacture comprising: an alumina based ceramic composition having a K IC (E&C) toughness of at least about 5MPam1/2; a Rockwell A hardness of at least 93 and a density of at least 98 percent of theoretical; said alumina based ceramic composition consisting essentially of: about 1.5-2.5 v/o silicon carbide whiskers; about 5 to 17.5 v/o ZrO 2 ; a residue of a magnesia addition added in an amount of about 0.03 to 3 v/o; an alumina based matrix wherein said silicon carbide whiskers, said zirconia and said residue of said magnesium oxide addition are substantially homogeneously distributed; and wherein tetragonal zirconia forms at least 4 v/o of said alumina based ceramic composition.
Claim 28
Dependent Claim
18 words
The alumina based ceramic composition according to claim 24 wherein said tetragonal zirconia is at least 6 v/o.
Claim 29
Dependent Claim
18 words
The alumina based ceramic composition according to claim 24 wherein said tetragonal zirconia is at least 7 v/o.
Claim 30
Dependent Claim
18 words
The alumina based ceramic composition according to claim 24 wherein said tetragonal zirconia is at least 8 v/o.
Claim 31
Dependent Claim
20 words
The alumina based ceramic composition according to claim 24 wherein said alumina based matrix is entirely alumina except for impurities.
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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) | 1993-10-22 | 1994-04-23 | 1994-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-22 | 1998-04-23 | 1998-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-22 | 2002-04-23 | 2002-10-23 | $7700.00 | Window Closed / Lapsed |