Forming process of anode foils for extra-high voltage aluminium electrolytic capacitors

Abstract

The invention provides a forming process of anode foils for extra-high voltage aluminium electrolytic capacitors, comprising the following steps: placing aluminium foils which undergo electrolytic corrosion in pure water at 90 DEG C or above to carry out pretreatment; then carrying out first-stage formation on the pretreated aluminium foils in aqueous solution containing 1-9wt% of boric acid and 0.01-0.6wt% of ammonium adipate; then treating the foils which undergo first-stage formation with phosphoric acid solution at the concentration of 1-10wt%; then treating the foils which undergo phosphoric acid treatment at high temperature; then carrying out second-stage formation on the foils which undergo high temperature treatment in the aqueous solution containing 2-10wt% of boric acid and 0.01-0.09wt% of ammonium pentaborate; then treating the foils which undergo second-stage formation in the phosphoric acid solution at the concentration of 1-10wt%; then treating the foils which undergo phosphoric acid treatment at high temperature; finally carrying out third-stage formation on the foils which undergo high temperature treatment in the mixed aqueous solution containing 2-10wt% of boric acid and 0.01-0.09wt% of ammonium pentaborate and carrying out post-treatment on the foils which undergo third-stage formation in the aqueous solution containing 1-13wt% of phosphoric acid and 0.1-6wt% of ammonia, and cleaning and then drying the foils which undergo post-treatment.

Description

technical field [0001] The invention relates to a processing technology of an anode foil, in particular to a chemical formation process of an anode foil for an ultra-high voltage aluminum electrolytic capacitor. Background technique [0002] Anode foils for electrolytic capacitors generally use boric acid, phosphoric acid, adipic acid, azelaic acid, citric acid, etc., or salts of these acids, at least one of which is used as an electrolyte, and is electrochemically oxidized on the surface of the corroded foil. Oxide film (γ-Al 2 o 3 ) as a dielectric, made into a foil, and the formation process of the oxide film is called chemical formation. There are many domestic reports on the research on the formation process, but the production of anode foil for UHV aluminum electrolytic capacitors by the existing method still cannot meet the technical requirements. Contents of the invention [0003] The object of the present invention is to provide a process for the formation of a...

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Problems solved by technology

There are many reports on the domestic research on the formation process, but the production of anode foil for