METHOD OF PHOSPHATIZING METALLIC SURFACE Russian patent published in 1998 - IPC

FIELD: machine building and metallurgy, more particularly preparation of phosphate coatings. SUBSTANCE: phosphate coatings is applied in solution which comprises (wt %): 1.15-3.06 zinc ions; 0.86-2.49 phosphate ((P₂O₅)) ions; 1.7-4.25 nitrate ions; 0.0096-0.029 nickel ions; 0.048-0.2 carbonic acid diamide; 0.0017-0.092 propionic acid production waste; and the water balance. Solution is heated to 70-75 C and phosphatized for 10-15 min. Zinc ions are added to solution as zinc scale which has the following components (%): at least 65 zinc; not higher than 0.6 lead; not higher than 1.5 aluminium; not higher than 1.5 iron; and not higher than 3.5 chlorine. EFFECT: improved protecting properties of phosphate coating, greater coating weight and increased corrosion resistance.