US4748016A
Expired / Lapsed
US
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Process of making finely divided powders of alkaline earth metal titanates
Assignee: Rhone Poulenc Specialites Chimiques
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Filing: 1984-09-14
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Granted: 1988-05-31
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Expires: 2004-09-14
Abstract
Abstract Finely divided powders of alkaline earth metal titanates, well suited for the fabrication of, e.g., ceramic resistors and condensers, are facilely prepared by (i) admixing a solution of an alkaline earth metal nitrate with a titanium sol having a pH ranging from 0.8 to 2.5 and which comprises elementary crystallites of TiO 2 having particle sizes ranging from 10 to 100 Å, agglomerated into submicronic masses having particle sizes ranging from 200 to 1000 Å, (ii) next drying the suspension which results, (iii) calcining said dried suspension at a temperature ranging from 700° to 1300° C. for from 30 minutes to 24 hours, under a NO x partial pressure decreasing from 1 to 0, and then (iv) optionally grinding the powder resulting from said step (iii).
Inventors
- 👤 Jean-Philippe Browaeys
- 👤 Jean-Francois Colombet
- 👤 Patrick Dougier
- 👤 Claude Magnier
- 👤 Regis Poisson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:51
CPC Classifications
C; C01; C01G; C01G23/00; C01G23/003; C01G23/006; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/468; C04B35/4682; C01P; C01P2002/00; C01P2002/60; C01P2004/00; C01P2004/50; C01P2004/60; C01P2004/61; C01P2004/62
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
196 words
A process for the preparation of finely divided alkaline earth metal titanate powder, comprising (i) admixing a solution of an alkaline earth metal nitrate with a titanium sol having a pH ranging from 0.8 to 2.5 and which comprises elementary crystallites of TiO 2 having particle sizes ranging from 10 to 100 Å, agglomerated into submicronic masses having particle sizes ranging from 200 to 1000 Å, to form a suspension, (ii) establishing a helical flow of gas in a reactor at a temperature ranging from 400° to 700° C. and allowing the gas to flow into a vortex well, (iii) injecting the suspension along the axis of symmetry of the helical flow of gases into the vortex well assuring drying of the suspension, the retention time of the suspension in the reactor being less than 1/10 of a second with the temperature of the exiting dried solids ranging from 120° to 160° C., (iv) calcining said dried suspension at a temperature ranging from 700° to 1300° C. for from 30 minutes to 24 hours, under a NO x partial pressure decreasing from 1 to 0, and thence optionally grinding the powder resulting from said step (iv).
Claim 2
Dependent Claim
196 words
A process for the preparation of finely divided alkaline earth metal titanate powder, comprising (i) admixing a solution of an alkaline earth metal nitrate with a titanium sol having a pH ranging from 0.8 to 2.5 and which comprises elementary crystallites of TiO 2 having particle sizes ranging from 10 to 100 Å, agglomerated into submicronic masses having particle sizes ranging from 200 to 1000 Å, to form a suspension, (ii) establishing a helical flow of gas in a reactor at a temperature ranging from 400° to 700° C. and allowing the gas to flow into a vortex well, (iii) injecting the suspension along the axis of symmetry of the helical flow of gases into the vortex well assuring drying of the suspension, the retention time of the suspension in the reactor being less than 1/10 of a second with the temperature of the exiting dried solids ranging from 120° to 160° C., (iv) calcining said dried suspension at a temperature ranging from 700° to 1300° C. for from 30 minutes to 24 hours, under a NO x partial pressure decreasing from 1 to 0, and thence optionally grinding the powder resulting from said step (iv).
Claim 3
Dependent Claim
27 words
The process as defined by Claim 1, wherein the step (i) the atomic ratio M/Ti, wherein M is an alkaline earth metal, ranges from 0.96 to 1.05.
Claim 4
Dependent Claim
15 words
The process as defined by claim 2, said atomic ratio ranging from 0.96 to 1.
Claim 5
Dependent Claim
27 words
The process as defined by claim 1, wherein the step (iii) the decreasing of the NO x partial pressure is carried out by gradual flushing with air.
Claim 6
Dependent Claim
22 words
The process as defined by claim 1, wherein the step (i) said titanium sol has a pH ranging from 1.8 to 2.2.
Claim 7
Dependent Claim
23 words
The process as defined by claim 1, wherein the step (i) said titanium sol is prepared by peptization of a titanium dioxide gel.
Claim 8
Dependent Claim
22 words
The process as defined by claim 6, said peptized gel comprises water and from 5 to 35% by weight of titanium dioxide.
Claim 9
Dependent Claim
20 words
The process as defined by claim 1, wherein the alkaline earth metal comprising said nitrate is barium, strontium or calcium.
Claim 10
Dependent Claim
23 words
The process as defined by claim 1, further comprising sintering a shaped article comprised of said finely divided alkaline earth metal titanate powder.
Claim 11
Dependent Claim
26 words
The process as defined by claim 1, wherein the suspension resulting from said step (i) comprises from about 5 to 15% by weight of dry solids.
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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) | 1991-05-31 | 1991-11-30 | 1992-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-31 | 1995-11-30 | 1996-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-31 | 1999-11-30 | 2000-05-31 | $7700.00 | Window Closed / Lapsed |