Terry R Cook

US Patent:

46473521, Mar 3, 1987

Filed:

Oct 30, 1985

Appl. No.:

6/792749

Inventors:

Terry L. Cook - Overland Park KS

Assignee:

ACRA, Inc. - Parkville MO

International Classification:

C25F 500

US Classification:

204146

Abstract:

A water-based composition for selective stripping of electroless applied nickel from ferrous, titanium and aluminum substrates is disclosed which includes a quantity of a chromic acid which functions as an oxidizing and electrolytic agent, an amount of globular sodium bisulfite which causes the chromium in the solution to substantially remain in a trivalent state, and a sufficient amount of phosphoric acid as a catalyst to enhance removal of electroless applied nickel by the oxidizing and electrolytic agent. Accelerated removal of electroless applied nickel is accomplished by confining the stripping composition in an enclosure, introducing a nickel-coated substrate into the stripping bath, providing a ferrous surface in the bath, connecting a DC source to the substrate serving as an anode while the ferrous surface functions as the cathode, maintaining the DC source at a voltage of about 6 volts, and heating the bath to a temperature of about 120. degree. F.