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US4140599A
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Process for producing porous aluminum anode element
Assignee: Fujitsu Ltd
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Filing: 1978-03-01
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Granted: 1979-02-20
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Expires: 1998-03-01
Abstract
Abstract A porous aluminum anode element having an increased effective surface area is prepared by an electrolytic etching process using an etchant solution containing CrO4-- in a higher concentration and a lower current density than those heretofore proposed. Currents of a digital signal type, such as a pulse current, or those of triangular, sawtooth, trapezoidal or staircase waveform, are preferred.
Inventors
- 👤 Tadashi Yamasaki
- 👤 Kentaro Hirata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:36
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; H01G9/048; H01G9/055; C; C25; C25F; C25F3/00; C25F3/02; C25F3/04; Y; Y10; Y10S; Y10S204/00; Y10S204/09
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
70 words
A process for the production of an aluminum anode element having a porous surface wherein an aluminum substrate is anodically etched in an aqueous solution containing 0.01 to 0.3 mol/l of Cl - and 0.5 to 3.0 mol/l of CrO 4 -- at an elevated temperature of 70° C. to 100° C. by flow of a D.C. pulsating current of a current density of 50 to 300 mA/cm 2 .
Claim 2
Dependent Claim
70 words
A process for the production of an aluminum anode element having a porous surface wherein an aluminum substrate is anodically etched in an aqueous solution containing 0.01 to 0.3 mol/l of Cl - and 0.5 to 3.0 mol/l of CrO 4 -- at an elevated temperature of 70° C. to 100° C. by flow of a D.C. pulsating current of a current density of 50 to 300 mA/cm 2 .
Claim 3
Dependent Claim
61 words
A process in accordance with claim 1 wherein the current is selected from a pulse current having a frequency of 10 to 80 Hz and a duty ratio of 60 to 95%, a pulsating current having a pulsation factor of 1.5 to 3.0 and a current of triangular, sawtooth, trapezoidal or staircase waveform having a frequency of 20 to 200 Hz.
Claim 4
Dependent Claim
33 words
A process in accordance with claim 1 wherein said process is carried out using a pulse current having a frequency of 10 to 80 Hz and a duty ratio of 60 to 95%.
Claim 5
Dependent Claim
31 words
A process in accordance with claim 1 wherein said process is carried out using a current of triangular, sawtooth, trapezoidal or staircase waveform having a frequency of 20 to 200 Hz.
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) | 1982-02-19 | 1982-08-21 | 1983-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-19 | 1986-08-21 | 1987-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-19 | 1990-08-21 | 1991-02-20 | $7700.00 | Window Closed / Lapsed |