| abstract |
The disclosure relates to a method of adjusting the layer weight in the phosphatisation of surfaces made of steel, galvanised steel, alloy-galvanised steel, or aluminium and its alloys with zinc-containing phosphatising solutions, the target layer weights being in the range 1-3.5 g/m2. The method is characterised in that the metal surfaces are dipped for between one and eight minutes in a phosphatising solution which contains 0.5-2 g/l zinc ions, 2-25 g/l phosphate ions, and 1.2-5 g/l hydroxylamine in free, ionic or complex-bound form; has a proportion of free acid of between 0 and 1.5 points; and has a temperature in the range 32-93 °C. |