US4665040A
Expired / Lapsed
US
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Alumina-zirconia ceramic powders and a method of making the same
Assignee: Kureha Corp
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Filing: 1984-12-10
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Granted: 1987-05-12
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Expires: 2004-12-10
Abstract
Abstract Alumina-zirconia ceramic powders comprise from 10% to 25% by weight of zirconium oxide having specific crystalline phases and from 75% to 90% by weight of aluminum oxide having specific crystalline phases, and have an average particle size of no more than 1,000 Ångstroms and a two-phase structure wherein the zirconium oxide phase is dispersed in the aluminum oxide phase. A method of making such alumina-zirconia ceramic powders comprises the steps of suspending composite powders having a specific chemical composition and a specific average particle size in water to form a slurry, freeze-drying the slurry, and calcining the freeze-dried powder at atmospheric pressure in air at a temperature of from 800° C. to 1,250° C.
Inventors
- 👤 Ryuichi Kurita
- 👤 Saburo Hori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 01:24
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/117; C04B35/119; C01; C01G; C01G25/00; C04B35/622; C04B35/626
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
125 words
Alumina-zirconia ceramic powders for use in the production of sintered bodies comprising from 10% to 25% by weight of zirconium oxide consisting of from 10% to 55% by volume of monoclinic phase and from 45% to 90% by volume of tetragonal phase, and from 75% to 90% by weight of aluminun oxide consisting of delta-phase as a minor phase and theta-phase as a major phase and being free of alpha-phase, said crystalline phases of said zirconium oxide and aluminum oxide being determined by means of the X-ray diffraction method, said alumina-zirconia ceramic powders exhibiting a two-phase structure wherein said zirconium oxide phase is dispersed in said aluminum oxide phase, and the average particle size of said alumina-zirconia ceramic powders being no more than 1,000 Ångstroms.
Claim 2
Dependent Claim
125 words
Alumina-zirconia ceramic powders for use in the production of sintered bodies comprising from 10% to 25% by weight of zirconium oxide consisting of from 10% to 55% by volume of monoclinic phase and from 45% to 90% by volume of tetragonal phase, and from 75% to 90% by weight of aluminun oxide consisting of delta-phase as a minor phase and theta-phase as a major phase and being free of alpha-phase, said crystalline phases of said zirconium oxide and aluminum oxide being determined by means of the X-ray diffraction method, said alumina-zirconia ceramic powders exhibiting a two-phase structure wherein said zirconium oxide phase is dispersed in said aluminum oxide phase, and the average particle size of said alumina-zirconia ceramic powders being no more than 1,000 Ångstroms.
Claim 3
Dependent Claim
35 words
The alumina-zirconia ceramic powders according to claim 1 wherein the crystallite diameter of tetragonal zirconium oxide is from 120 to 300 Ångstroms on the basis of the calculation of the peak width of X-ray diffraction.
Claim 4
Dependent Claim
24 words
The alumina-zirconia ceramic powders according to claim 1 wherein the content of chlorine ion is no more than 500 ppm (on a weight basis).
Claim 5
Independent Claim
157 words
A method of making alumina-zirconia ceramic powders which comprises the steps of providing powders of average particle size of no more than 1,000 Ångstroms comprising from 75% to 90% by weight of aluminum oxide consisting of delta-phase as a minor phase and theta-phase as a major phase and being free of alpha-phase and from 10% to 25% by weight of zirconium oxide consisting of from 10% to 55% by volume of monoclinic phase and from 45% to 90% by volume of tetragonal phase which are obtained by subjecting aluminum chloride and zirconium chloride containing no more than 4 mole % of hafnium chloride as feedstocks to a vapor phase oxidation/pyrolysis process; suspending said powders in water to form an aqueous slurry having solid concentration of from 9% to 25% by weight; freeze drying said slurry; and calcining said freeze-dried powders at atmospheric pressure in an air atmosphere at a temperature of from 1000° C. to 1,250° C.
Claim 6
Independent Claim
157 words
A method of making alumina-zirconia ceramic powders which comprises the steps of providing powders of average particle size of no more than 1,000 Ångstroms comprising from 75% to 90% by weight of aluminum oxide consisting of delta-phase as a minor phase and theta-phase as a major phase and being free of alpha-phase and from 10% to 25% by weight of zirconium oxide consisting of from 10% to 55% by volume of monoclinic phase and from 45% to 90% by volume of tetragonal phase which are obtained by subjecting aluminum chloride and zirconium chloride containing no more than 4 mole % of hafnium chloride as feedstocks to a vapor phase oxidation/pyrolysis process; suspending said powders in water to form an aqueous slurry having solid concentration of from 9% to 25% by weight; freeze drying said slurry; and calcining said freeze-dried powders at atmospheric pressure in an air atmosphere at a temperature of from 1000° C. to 1,250° C.
Claim 7
Dependent Claim
41 words
The method of making alumina-zirconia ceramic powders according to claim 4 wherin said freeze-drying is carried out by freezing said powders in a dry ice-methanol bath and thereafter vacuum drying said powders under a pressure of no more than 1 Torr.
References Cited (Backward Citations)
US4298385A
Cited
US4331048A
Cited
US4396724A
Cited
US4491482A
Cited
US4506024A
Cited
US4532224A
Cited
US4520114A
Cited
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| 3.5 Years (Year 4) | 1990-05-11 | 1990-11-10 | 1991-05-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-11 | 1994-11-10 | 1995-05-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-11 | 1998-11-10 | 1999-05-12 | $7700.00 | Window Closed / Lapsed |