Process for activating the formation of a phosphate layer on metals, and means for carrying out the process

摘要

In the pretreatment of metal surfaces by means of activator-containing aqueous prewashing baths before the subsequent phosphating, the reduction in activity is countered by contacting the metal surfaces with a prewashing bath which additionally contains montmorillonite, especially in the form of bentonite, in a quantity of 0.01 to 10 g/l. Prewashing baths which contain finely disperse titanium phosphate or finely disperse tertiary zinc phosphate are preferably used before phosphating with zinc phosphate solutions, and baths containing finely disperse tertiary manganese phosphate or finely disperse iron(II) manganese phosphate are used before phosphating with manganese phosphate solutions.