| 摘要 |
PURPOSE:To permit direct joining of electrodeposition painting on a chromate film by washing a steel plate, which is applied thereon with Zn-Ni alloy plating, forming a specific amt. of the chromate film thereon and subjecting the steel plate to hot water washing and sealing treatment under specific conditions. CONSTITUTION:Zn-Ni alloy plating of about 10-16% content of Ni is applied on a steel plate of about 0.6-1.2mm. thickness by an electroplating method. The steel plate is washed, then a chromate film of >=2mg/m<2> coating weight of chromium is formed on the washed surface with an aq. soln. contg. Cr<6+>. The steel plate is then washed for 1 second - several seconds in hot water kept at >=60 deg.C to remove the water soluble components in the chromate film. The washed steel plate is dried and is then subjected to sealing by using an aq. soln. contg. >=0.2g/l concn. of Cr<6+>, more preferably, 0.2-1.5g/l chromic anhydride. The treatment is accomplished at a room temp. or above the about <=80 deg.C. The treated steel plate is dried after roll squeezing. |
