Method of applying phosphate coatings to metal surfaces

摘要

PCT No. PCT/EP95/04774 Sec. 371 Date Jun. 6, 1997 Sec. 102(e) Date Jun. 6, 1997 PCT Filed Dec. 5, 1995 PCT Pub. No. WO96/17977 PCT Pub. Date Jun. 13, 1996A method is disclosed for applying phosphate coatings to surfaces of zinc, iron, aluminum, and the alloys thereof by wetting with a phosphatizing solution containing divalent cations and phosphate to form a liquid film, and subsequently drying on the liquid film wherein the metal surfaces are wetted with a phosphatizing solution, which is free from elements of sub-groups 5 and 6 of the Periodic Table, said phosphatizing solution containing: 0.5 to 8 g/l nickel; 2 to 20 g/l manganese; 18 to 170 g/l of phosphate (calculated as P2O5); and has an acid number of 0.4 to 0.8, such that after drying on, a phosphate layer having a weight per unit area of 0.3 to 3.0 g/m2, is obtained, where in the case of phosphatizing surfaces of iron, aluminum or the alloys thereof, the phosphatizing solution necessarily contains 0.5 to 5 g/l of zinc, and in the case of phosphatizing surfaces of zinc or zinc alloys the phosphatizing solution either contains zinc or is free from zinc.