| 摘要 |
The invention relates to a process for phosphating galvanised steel surfaces, preferably electrolytically or hot-dip-galvanised surfaces of steel strip, by treating them in a bath or spray with acid, aqueous phosphating solutions, with the workpieces given a d.c. cathodic treatment at the same time. In the process: a) phosphating solutions are used containing the following components: Zn2+ cations in the range from 0.1 to 5 g/l, PO43--anions in the range from 5 to 50 g/l, NO3- anions in the range from 0'.1 to 50 g/l, and Mn2+ cations in the range from 0.1 to 5 g/l, and Cu2+ cations in the range from 0.001 to 1 g/l; b) the following conditions are observed: pH of the phosphating solution in the range from 1.5 to 4.5, temperature of the phosphating solution in the range form 10 to 80 C, treatment time in the range from 1 to 300 sec; c) and the workpieces are also cathodically treated with a direct current with a density in the range from 0.01 to 100 mA/cm2 during phosphating. |
