| 摘要 |
Method of zinc phosphatization of substrates essentially based on iron, zinc or their alloys, comprising successively: (1) one or several alkaline degreasing steps, (2) one or several rinsing steps with running city water, (3) an activating and refining step, (4) the zinc phosphatization step proper, (5) one or several rinsing steps with water, (6) preferably, a passivating final rinsing step, particularly by means of salts of hexavalent chromium or mixtures of hexavalent chromium and trivalent chromium characterized by the fact that, to carry out the activating and refining step, recourse is had to a bath comprising, besides the conventional constituents among which are particularly at least one Jernstedt salt in a proportion corresponding to about 1 to 100 ppm of titanium, a proportion of 10 to 700 ppm, preferably from 50 to 200 ppm, of at least one alkane-phosphonic acid of formula <IMAGE> (I) or at least one of the alkali or ammonium salts corresponding to the abovesaid alkane-phosphonic acids, the pH of the bath being from 7 to 9.5, preferably from 7.5 to 9. |
