PROCESS FOR CONDITIONING THE COPPER OR COPPER-ALLOY EXTERNAL SURFACE OF AN ELEMENT OR MOULD FOR THE CONTINUOUS CASTING OF METALS, OF THE TYPE INCLUDING A NICKEL PLATING STEP AND A NICKEL REMOVAL STEP

摘要

The subject of the invention is a process for conditioning the copper or copper-alloy external surface of an element of a mould for the continuous casting of metals, of the type including a step of nickel plating of the said surface and a step of nickel removal therefrom, characterized in that: -a preparation of the said surface, comprising in succession an operation of cleaning the said bare surface, an operation of pickling the said bare surface in an oxidizing acid medium and an operation of brightening the said bare surface, is carried out; -then, an operation of nickel plating of the said bare surface is carried out by electroplating, by placing the said element as the cathode in an electrolyte consisting of an aqueous nickel sulphamate solution containing from 60 to 100 g/l of nickel; -then, after the said element has been used, an operation of partially or completely removing the nickel from the said surface electrolytically is carried out, by placing the said element as the anode in an electrolyte consisting of an aqueous nickel sulphamate solution containing from 60 to 100 g/l of nickel and sulphamic acid in an amount from 20 to 80 g/l, and the pH of which is less than or equal to 2; -and then a new nickel plating of the said surface is carried out, if appropriate preceded by a preparation of the surface of the bared copper as explained previously.