| 摘要 |
PURPOSE:To obtain a chromate film having superior performance by carrying out composite electrolysis by cathodic electrolysis in a chromate bath contg. specified cations and immediate anodic electrolysis. CONSTITUTION:A chromate bath contg. Cr<6+>, PO4<3->, one or two kinds of fluorine compounds and one or more kinds of ions selected among ions of Zn, Ni, Co, Al, Mg, Sn, Mn and Pb is prepd. A Zn or Zn alloy plated steel sheet, an Al or Al alloy plated steel sheet or a Pb or Pb alloy plated steel sheet is cathodically electrolyzed in the chromate bath to form a chromate film. Anodic electrolysis is then carried out at once to modify the chromate film.
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