Automatic Control of Process Solutions: the Use of Insoluble Anodes and Ion-exchange Membranes

摘要

Stable composition of various process solutions is maintained by adding those components which are consumed in the course of the operation and by continuous or periodic removal of reaction products and impurities. A combination of soluble and insoluble anodes connected to separate rectifiers allows to prevent excessive built-up of metal ions. A half-cell with a cationic membrane and a cathode inside immersed into the process tank with an insoluble anode is used for the regeneration of passivating, etching and stripping plating solutions. A combination of two half-cells with insoluble anodes, cationic and anionic membranes allows maintaining constant pH of trivalent chromium plating bath and to remove from it access of sulfate ions.