METHOD FOR ELECTROCHEMICAL PHOSPHATING OF METAL SURFACES, PARTICULARLY STAINLESS STEEL, AND APPLICATION OF AN AQUEOUS PHOSPHATING SOLUTION FOR SUCH A METHOD

摘要

A method for electrochemical phosphating of metal surfaces, particularly stainless steel, in connection with cold forming of metal workpieces, which method provides the cold formed work-piece with a lubricant after phosphating, involves an electrochemical phosphating through a cathodic process applying an aqueous phosphating solution containing: 0.5 to 100 g Ca2+/1, 0.5 to 100 g Zn2+/1, 5 to 100 g PO¿4?3-/1, 0 to 100 g NO¿3?-/1, 0 to 100 g ClO¿3?-/1 and 0 to 50 g F?- or Cl-¿/1, by which the temperature of the solution is between 0 and 95 °C, the pH-value of the solution is between 0.5 and 5, and the current density is between 0.1 and 250 mA/cm2. This gives a good lubrication effect, a good adhesion to the metal surface, particularly stainless steel, and a more expedient texture than ordinary phosphating.