US4035191A
Expired / Lapsed
US
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Tetragonally stabilized zirconia ceramic
Assignee: Didier Werke AG
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Filing: 1975-09-04
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Granted: 1977-07-12
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Expires: 1995-09-04
Abstract
Abstract Mature zirconia ceramic compositions stabilized in the monoclinic and tetragonal structure with 0.1-5% ZnO and as little as 0.5% of a primary stabilizer selected from MgO, Y 2 O 3 or combinations thereof. Compacted ceramic compositions are fired and matured at temperatures below the volatilization point of ZnO and in the range of 2750°-2950° F. Zirconia is conventionally batched with magnesia, yttria or mixtures thereof, with or without other known stabilizers including ceria and calcia, together with up to about 5% ZnO and then compacted and sintered at a temperature which retains at least 0.1% ZnO in the fired body. Conventional cooling is prescribed. Subsequent thermal cycling of the fired body between 400° and 2500° F. reveals a stable body with no degradation in strength. Magnesia stabilized compositions show no signs of early destabilization on thermal cycling and may even show increasing room temperature strength as cycling progresses.
Inventors
- 👤 Herbert L. Johns
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:23
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/48; C04B35/486
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
76 words
A mature, tetrastabilized zirconia fired composition consisting essentially of, by weight on the oxide basis, 0.1-5.0% ZnO and at least 0.5% of a primary stabilizer selected from 0.25% up to less than about 4% MgO, 0.25% up to less than about 4% Y 2 O 3 and combinations thereof, the balance substantially being ZrO 2 , said fired composition having less than 10% cubic structure and at least 5% tetragonal structure by volume at room temperature.
Claim 2
Dependent Claim
76 words
A mature, tetrastabilized zirconia fired composition consisting essentially of, by weight on the oxide basis, 0.1-5.0% ZnO and at least 0.5% of a primary stabilizer selected from 0.25% up to less than about 4% MgO, 0.25% up to less than about 4% Y 2 O 3 and combinations thereof, the balance substantially being ZrO 2 , said fired composition having less than 10% cubic structure and at least 5% tetragonal structure by volume at room temperature.
Claim 3
Independent Claim
134 words
A method of producing a tetrastabilized zirconia fired composition having less than 10% cubic structure and at least 5% tetragonal structure at room temperature and being characterized by a retained strength upon thermal cycling below 2,900° F. comprising, (a) blending a raw material batch consisting essentially of, by weight on the oxide basis 0.1-5.0% ZnO, at least 0.5% of a primary stabilizer selected from 0.25 up to less than about 4% MgO, 0.25 up to less than about 4% Y 2 O 3 and combinations thereof, the balance substantially being ZrO 2 , (b) shaping said batch into a green body, and (c) sintering said body to bring about ceramic bonding at a temperature above about 2,550° F. for a time after which at least 0.1% of the ZnO remains in the fired body.
Claim 4
Independent Claim
134 words
A method of producing a tetrastabilized zirconia fired composition having less than 10% cubic structure and at least 5% tetragonal structure at room temperature and being characterized by a retained strength upon thermal cycling below 2,900° F. comprising, (a) blending a raw material batch consisting essentially of, by weight on the oxide basis 0.1-5.0% ZnO, at least 0.5% of a primary stabilizer selected from 0.25 up to less than about 4% MgO, 0.25 up to less than about 4% Y 2 O 3 and combinations thereof, the balance substantially being ZrO 2 , (b) shaping said batch into a green body, and (c) sintering said body to bring about ceramic bonding at a temperature above about 2,550° F. for a time after which at least 0.1% of the ZnO remains in the fired body.
Claim 5
Dependent Claim
15 words
The method of claim 2 wherein said firing temperature is less than about 2,950° F.
Claim 6
Dependent Claim
77 words
A mature, tetrastabilizer zirconia fired composition consisting essentially of, by weight on the oxide basis, 0.1-5.0% ZnO and 0.25% up to less than about 4% MgO, the balance substantially being ZrO 2 , said zirconia composition being less than 10% cubic structure and more than 5% tetragonal structure at room temperature and being characterized by a retained strength and lack of early destabilization upon thermal cycling or holding at temperatures in the range of about 1,650°-2,550° F.
Claim 7
Dependent Claim
77 words
A mature, tetrastabilizer zirconia fired composition consisting essentially of, by weight on the oxide basis, 0.1-5.0% ZnO and 0.25% up to less than about 4% MgO, the balance substantially being ZrO 2 , said zirconia composition being less than 10% cubic structure and more than 5% tetragonal structure at room temperature and being characterized by a retained strength and lack of early destabilization upon thermal cycling or holding at temperatures in the range of about 1,650°-2,550° F.
Claim 8
Independent Claim
110 words
A method of producing a tetrastabilized zirconia fired composition having less than 10% cubic structure at room temperature and which does not rapidly destabilize upon thermal cycling or holding at temperatures in the range of 1,650°-2,550° F. comprising (a) blending a raw material batch consisting essentially of, by weight on the oxide basis, 0.1-5.0% ZnO, 0.5% up to less than about 4% MgO, the balance substantially being ZrO 2 , (b) shaping said batch into a green body, and (c) sintering said body to bring about ceramic bonding at a temperature above about 2,550° F. for a time after which at least 0.1% of said ZnO remains in the body.
Claim 9
Independent Claim
110 words
A method of producing a tetrastabilized zirconia fired composition having less than 10% cubic structure at room temperature and which does not rapidly destabilize upon thermal cycling or holding at temperatures in the range of 1,650°-2,550° F. comprising (a) blending a raw material batch consisting essentially of, by weight on the oxide basis, 0.1-5.0% ZnO, 0.5% up to less than about 4% MgO, the balance substantially being ZrO 2 , (b) shaping said batch into a green body, and (c) sintering said body to bring about ceramic bonding at a temperature above about 2,550° F. for a time after which at least 0.1% of said ZnO remains in the body.
Claim 10
Dependent Claim
15 words
The method of claim 5 wherein said firing temperature is less than about 2,950° F.
Claim 11
Dependent Claim
33 words
The fired composition of claim 1 consisting essentially of, by weight on the oxide basis, 0.5-3% MgO, 0.5-2% Y 2 O 3 , 0.5-2.5% ZnO and the balance substantially being ZrO 2 .
Claim 12
Dependent Claim
15 words
The fired composition of claim 1 wherein ZnO is not more than 2% by weight.
Claim 13
Dependent Claim
22 words
The fired composition of claim 1 wherein the balance consists of ZrO 2 plus less than 0.5% by weight of minor impurities.
Claim 14
Dependent Claim
22 words
The fired composition of claim 7 wherein the balance consists of ZrO 2 plus less than 0.5% by weight of minor impurities.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-11 | 1981-01-10 | 1981-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-11 | 1985-01-10 | 1985-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-11 | 1989-01-10 | 1989-07-12 | $7700.00 | Window Closed / Lapsed |