Methods of plating zinc-containing coatings under alkaline conditions
The anode is separated from the alkaline electrode to avoid undesirable secondary reactions in an alkali zinc nickel electroplating bath.
1. A method for plating zinc-containing coatings under alkaline conditions from an electroplating bath comprising:
providing an electroplating cell having an anode and a cathode;
separating said anode from said cathode by an ion-exchange membrane to provide an anode compartment and a cathode compartment;
introducing an alkaline electrolyte with metal ions for a zinc-nickel coating into said cathode compartment; and
introducing a complex former for nickel into said electrolyte of said electroplating bath wherein said complex former comprises an amine.
2. The method of claim 1 comprising introducing an anolyte into said anode compartment, wherein said anolyte is selected from the group consisting of sulfuric acid, phosphoric acid, methanesulfonic acid, amidosulfonic acid and/or phosphonic acid.
3. A method of inhibiting cyanide formation in an alkaline electroplating bath comprising an anode and a cathode with an alkaline electrolyte with metal ions for a zinc-metal coating comprising:
introducing an alkaline electrolyte with metal ions for a zinc-containing coating;
introducing a complex former into said alkaline electrolyte, said complexing agent comprising an amine; and
at least substantially preventing contact between said anode and said amine by separating said anode from said cathode member to provide an anode compartment and a cathode compartment.
4. The method of claim 3 comprising at least substantially preventing contact between said anode and said amine by separating said anode from said cathode with a selectively permeable membrane capable of allowing at least substantially unimpeded flux of current therethrough, but being at least substantially impermeable to said amine.
5. The method of claim 4 wherein said membrane comprises an ion-exchange membrane.
6. The method of claim 4 wherein said membrane comprises a polymeric material having a low electrical resistance and being at least substantially impermeable to amines.
7. The method of claim 4 wherein said membrane comprises a perfluorinated polymer.