Method of producing ultra stable aluminum oxide for high volt electrolytic capacitors and product thereof
US5143591A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 11, 1991 |
| Grant date | Sep 1, 1992 |
| Priority date | — |
| Expiry date | Jun 11, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01G9/055
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The invention relates to a method of producing aluminum capacitor foil adapted for use in high voltage AC motor start capacitors. Aluminum foil is electrolytically etched in a hot aqueous solution of sodium cloride and then immersed in a hot solution of nitric acid. The foil is immediately thereafter passivated in a dilute aqueous solution of phosphoric acid. The passivated foil is electrolytically treated at a first voltage of at least 150 but not greater than 250 volts in a solution of an ammonium salt of a phosphate, a silicate or a vanadinate to substantially reduce the leakage current, and further electrolytically treated at a second voltage of a magnitude about twice that of the first voltage in a solution of an ammonium salt of an aliphatic dicarboxylic acid of at least 9 carbon atoms and ammonium phosphate until an essentailly amorphous oxide is formed on the foil.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.