PROCESS FOR ELECTROPLATING METAL PLATE WITH ALUMINUM

摘要

A process for electroplating a metal plate with aluminum in a molten salt bath composed of 40 to 80 mol % of an aluminum halide and 20 to 60 mol % of an N-alkylpyridinium halide or a molten salt bath further containing an organic solvent, which comprises conducting electrolysis in an activating bath having the same composition as that of the above-described molten salt bath using the metal plate as the anode to activate the plate before plating, thus improving adhesion of aluminum deposit. Furthermore the purity of aluminum in the deposit is enhanced either by dipping metallic aluminum in the molten salt bath for a time, or by dipping aluminum cathode and anode in the molten salt bath and conducting preliminary electrolysis at a current density of up to 0.5 A/dm<2> to thereby refine the bath. ABSTRACT In electroplating aluminum on a metal sheet with use of a molten salt bath comprised of from 40 to 80 mol % of an aluminum halide and from 20 to 60 mol % of an N-alkylpyridinium halide, or a molten salt bath obtained by mixing an organic solvent in said first-mentioned bath, said metal sheet is activated to improve deposit adhesion by carrying out, before plating, electrolysis on said metal sheet, bringing it to serve as an anode and with use of an activating bath having the same composition as said molten salt bath. Also, the bath is purified by leaving metallic aluminum immersed in the bath, or by carrying out preliminary electrolysis under a current density of 0.5 A/dm<2> or less with immersion of an anode and a cathode both made of metallic aluminum in the molten salt bath.