Electrolytes for electrochemically treated metal plates

摘要

According to the invention there is provided an electrochemical process for applying a firmly bonded insoluble metal oxide-organic complex on a metal surface by employing the metal as anode and a water-soluble polybasic organic acid as electrolyte. The polybasic acid may be a polyphosphonic acid, polyphosphoric and polycarboxyl acid, or polysulfonic acid and is advantageously polymeric. Polyvinyl phosphonic acid (PVPA) is a preferred electrolyte. Direct current is used. The insoluble metal oxide-organic complex formed is composed of anodic oxide combined with polyacid, which forms a protective layer on the metal of improved corrosion resistance. The metal oxide-organic complex is well-suited to bond light sensitive coatings thereto. The metal may be steel, aluminum or magnesium. The process is economical and the product novel.