PROCESS OF PHOSPHATIZING METAL SURFACES

The invention concerns a method of phosphating metal surfaces consisting at least partially of iron or steel using low-zinc technology, in which the metal surfaces are brought into contact with aqueous acidic phosphating solutions at between 30 and 65 .degree.C for between 1 and 8 minutes. The phosphating solutions contain: between 0.4 and 2.0 g/l Zn ; between 7 and 25 g/l P2O5; between 0.005 and 0.5 g/l peroxide (calculated as H2O2); and between 0.01 and 10 g/l formiate (calculated as formiate ion). The phosphating solutions are free from chlorate and added nitrite, the weight ratio of free P2O5 to total P2O5 therein is set at a value of between 0.03 and 0.20, and the amount of free acid is set at a value of between 0.5 and 2.5. Additionally, the phosphating solutions can contain up to 30 g/l nitrate and manganese, magnesium calcium, lithium, tungstate, vanadate, molybdate or combinations thereof optionally also nickel and/or cobalt each in amounts of up to 3 g/l and optionally also up to 0.030 g/l copper. The weight ratios of Mn : Zn, Mg : Zn, Ca : Zn and optionally of Ni and/or Co : Zn should be at most 2 : 1 in each case. The method is suitable in particular far preparing metal surfaces for subsequent electrophoretic enamelling, in particular cathodic electrophoretic enamelling.