Preparation of metal surfaces for vitreous enameling

Abstract

Disclosed is a process in which a phosphate layer is formed on a metal surface in preparation for the subsequent application of a vitreous enamel coating, wherein a phosphating solution is used which contains essentially nickel and/or cobalt as a layer-forming cation in amounts of 0.5 to 3 g/l as well as 5 to 20 g/l phosphate (calculated as P.sub.2 O.sub.5), 0.1 to 0.5 g/l molybdate (calculated as MoO.sub.3), 0.2 to 2 g/l fluoride (calculated as F), 1 to 10 g/l nitrate (calculated as NO.sub.3), and optionally also 0.1 to 5 g/l urea. It is particularly desirable to use essentially zinc-free phosphating solutions at temperatures preferably of 60.degree. to 70.degree. C. for 2 to 12 minutes to form a phosphate layer having a coating weight of 1.0 to 2.0 g/m.sup.2.

Dependencies are inferred from the claim text.