Abstract: An aqueous solution contains phosphate for producing layers of phosphate on metal surfaces selected from the group consisting of iron, steel, zinc, zinc alloys, aluminum and aluminum alloys. The solution contains 0.3 to 5 g Zn2+/1, 0.1 to 2 g nitroguanidine/1 and 0.05 to 0.5 g hydroxylamine/l, with an S-value amounting to 0.03 to 0.3 and the ratio of the weight of Zn2+ to P2O5=1:5 to 1.30.

Abstract: A process to form phosphate coatings on individual parts of metal which at least on part of their surface consists of iron or steel. The individual parts are contacted at a temperature in the range of from 60 to 100 degrees centigrade for 3 to 30 seconds with an aqueous phosphating solution which contains 10 to 80 g/l zinc, 12 to 80 g/l phosphate (calculated as P.sub.2 O.sub.5), 40 to 150 g/l nitrate and, in addition 0.1 to 10 g/l fluoride, 0.01 to 10 g/l nickel, 0.0001 to 0.1 g/l copper, and may also contain tartaric acid, citric acid and/or manganese and in which the ratio of free acid to total acid has been adjusted to (0.1 to 0.3):1 and which contains at least 80 points of total acid and is virtually free of iron(II) ions. Prior to phosphating treatment, the individual parts may be cleaned and may optionally be treated to remove rust, scale and phosphate layers and/or be activated. After the phosphating treatment they may be passivated with an after-rinse solution.

Abstract: In a process for phosphating composite metals containing steel and zinc surfaces using phosphating solutions based on zinc phosphate by the dipping process, in order to achieve satisfactory formation of the phosphate layer, the composite metals are subjected to preliminary dipping for a maximum of 30 seconds in a phosphating solution based on zinc phosphate in order to initiate the formation of the phosphate layer, and are then conveyed to the main dip-phosphating zone.It is advantageous to spray the composite metals with a phosphating solution based on zinc phosphate while they are being conveyed from the preliminary to the main dip-phosphating zone, and it is advisable to limit the duration of the conveying and thus of the spraying treatment to a maximum of 30 seconds.