PURPOSE: To produce a one-side metal-plated steel plate having a superior phosphate film by forming a metal plating layer on one side of a steel plate by an electroplating method then spraying a suspension contg. in soluble phosphate of metals on the nonplated side.
CONSTITUTION: After Zn or Pb-Sn is electroplated on one side of a steel plate for automobiles, the nonplated surface of one side is degreased by alkali cleaning and pickled, thence it is electrolyzed in an electrolytic bath, thereby removing the oxide film of the surface and activating the surface. Next, a suspension of insoluble phosphate of bivalent metals such as Zn3(PO4)2 or Ca(PO4)2 or insoluble phosphate of tervalent metals such as AlPO4 or FePO4 is sprayed for about 2W10sec at ordinary temp. W60°C, under 2W10kg/cm2 pressure, whereby the phosphate film of the above-mentioned metals is formed. The one-side metal-plated steel plate having the highly corrosion resistant plated surface and the phosphate film of superior corrosion resistance and paint adhesiveness after paint coating is produced.
OOSAWA MASAMI
KAMATA MINORU
OKAMOTO SUSUMU
NOMURA YUKIO
