Patent ID: 8784991

Claim:
A process comprising coating a metallic surface with a composition, wherein said composition consists of a) from 0.02 to 1 g/L of at least one compound selected from the group consisting of a silane, a silanol, a siloxane and a polysiloxane, wherein the silane, the silanol, the siloxane or the polysiloxane contains at least one group selected from the group consisting of an amino group, a urea group and a ureido group; b) at least two complex fluorides of formula MeF 6 wherein Me is a metal selected from the group consisting of titanium, hafnium, zirconium, aluminum and boron; water, and c) at least one cation selected from the group consisting of cerium, chromium, iron, calcium cobalt, copper, magnesium, manganese, molybdenum, nickel, niobium, tantalum, yttrium, zinc, and tin; wherein the total amount of the complex fluorides ranges from 0.01 to 100 g/L.