METHOD FOR OXALATING THE GALVANIZED SURFACE OF SHEET METAL

摘要

A method for forming a zinc oxalate coating on the surface of a strip or sheet of metal covered with a zinc or zinc alloy coating other than zinc/iron coatings, with the aid of an aqueous solution consisting of oxalic acid having a concentration of between 5.10^-3 and 0.1 mole/l, and at least one compound and/or ion of an oxidant zinc metal having a concentration of between 10^-6 and 10^-2 mole/l, and possibly a wetting agent. The inventive method enables sheet metal to be treated at very high speeds without using large amounts of oxidant. It facilitates management of treatment baths. The invention can be used in the lubrication of sheet metal, especially for die stamping.