US4520114A
Expired / Lapsed
US
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Production of metastable tetragonal zirconia
Assignee: Celanese Corp
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Filing: 1984-08-22
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Granted: 1985-05-28
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Expires: 2004-08-22
Abstract
Abstract This invention provides a process for producing a fine grain metastable tetragonal zirconia which has an average particle size less than about 1000 angstroms in diameter. The process involves multistage thermolysis of precursor solids comprising a homogeneous mixture of β-ketonate compounds of zirconium and a stabilizer metal such as yttrium.
Inventors
- 👤 Lawrence D. David
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:53
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/48; C04B35/486; B; B82; B82Y; B82Y30/00; C01; C01G; C01G25/00; C01G25/02; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2002/60; C01P2004/00; C01P2004/60; C01P2004/64; C01P2006/00; C01P2006/80
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
125 words
A process for the production of fine grain metastable tetragonal zirconia which comprises (1) preparing a homogeneous solution by dissolving in a solvent medium zirconium β-diketonate and a metastabilizing quantity of metal β-diketonate selected from alkaline earth and yttrium metal β-diketonates, (2) removing the solvent medium to provide a residual mass of precursor solids, (3) pyrolyzing the precursor solids in an inert atmosphere at a temperature between about 300°-800° C. until the precursor solids have a carbon content between about 1-10 weight percent, based on the weight of precursor solids, and (4) calcining the precursor solids in the presence of molecular oxygen at a temperature between about 300°-800° C. to yield metastable tetragonal zirconia powder having an average particle size less than about 1000 angstroms.
Claim 2
Dependent Claim
125 words
A process for the production of fine grain metastable tetragonal zirconia which comprises (1) preparing a homogeneous solution by dissolving in a solvent medium zirconium β-diketonate and a metastabilizing quantity of metal β-diketonate selected from alkaline earth and yttrium metal β-diketonates, (2) removing the solvent medium to provide a residual mass of precursor solids, (3) pyrolyzing the precursor solids in an inert atmosphere at a temperature between about 300°-800° C. until the precursor solids have a carbon content between about 1-10 weight percent, based on the weight of precursor solids, and (4) calcining the precursor solids in the presence of molecular oxygen at a temperature between about 300°-800° C. to yield metastable tetragonal zirconia powder having an average particle size less than about 1000 angstroms.
Claim 3
Dependent Claim
12 words
A process in accordance with claim 1 wherein the β-diketonate is acetylacetonate.
Claim 4
Dependent Claim
15 words
A process in accordance with claim 1 wherein the solution medium comprises an organic solvent.
Claim 5
Dependent Claim
15 words
A process in accordance with claim 1 wherein the solution medium additionally includes a surfactant.
Claim 6
Dependent Claim
25 words
A process in accordance with claim 1 wherein the residual mass of precursor solids produced in step (2) is in the form of a gel.
Claim 7
Dependent Claim
16 words
A process in accordance with claim 1 wherein the inert atmosphere in step (3) is nitrogen.
Claim 8
Dependent Claim
20 words
A process in accordance with claim 1 wherein the calcining in step (4) is conducted in the presence of air.
Claim 9
Dependent Claim
25 words
A process in accordance with claim 1 wherein the zirconia powder produced in step (4) is substantially free of monoclinic and cubic phase crystal structures.
Claim 10
Dependent Claim
22 words
A process in accordance with claim 1 wherein the zirconia powder produced in step (4) is comprised of particles having equiaxed dimensions.
Claim 11
Dependent Claim
84 words
A metastable tetragonal zirconia powder with a crystal structure which is a solid solution of zirconium dioxide and a metastabilizing quantity between about 1-30 mole percent of metal oxide selected from alkaline earth and yttrium metal oxides, and further characterized by: (a) a crystallite size up to about 500 angstroms; (b) an average particle size less than about 1000 angstroms; (c) particles of equiaxed dimensions; and (d) is substantially free of monoclinic and cubic phase crystal structures as determined by X-ray diffraction pattern analysis.
Claim 12
Dependent Claim
84 words
A metastable tetragonal zirconia powder with a crystal structure which is a solid solution of zirconium dioxide and a metastabilizing quantity between about 1-30 mole percent of metal oxide selected from alkaline earth and yttrium metal oxides, and further characterized by: (a) a crystallite size up to about 500 angstroms; (b) an average particle size less than about 1000 angstroms; (c) particles of equiaxed dimensions; and (d) is substantially free of monoclinic and cubic phase crystal structures as determined by X-ray diffraction pattern analysis.
Claim 13
Dependent Claim
17 words
A metastable tetragonal zirconia powder in accordance with claim 10 wherein the metal oxide is yttrium oxide.
Claim 14
Dependent Claim
17 words
A metastable tetragonal zirconia powder in accordance with claim 10 wherein the metal oxide is magnesium oxide.
Claim 15
Dependent Claim
17 words
A metastable tetragonal zirconia powder in accordance with claim 10 wherein the metal oxide is calcium oxide.
Claim 16
Dependent Claim
17 words
A metastable tetragonal zirconia powder in accordance with claim 10 wherein the metal oxide is strontium oxide.
Claim 17
Dependent Claim
25 words
A metastable tetragonal zirconia powder in accordance with claim 10 wherein the content of metal oxide impurities is less than about 100 parts per million.
Claim 18
Dependent Claim
34 words
A method of improving the fracture toughness and strength of a ceramic substrate which comprises incorporating therein between about 2-30 percent by volume of fine grain metastable tetragonal zirconia as defined in claim 10.
Claim 19
Dependent Claim
12 words
A ceramic body produced in accordance with the method of claim 16.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1988-05-27 | 1988-11-26 | 1989-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-27 | 1992-11-26 | 1993-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-27 | 1996-11-26 | 1997-05-28 | $7700.00 | Window Closed / Lapsed |