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Article: PLATING CLINIC.(Brief Article)
- Article from:
- Products Finishing
- Article date:
- June 1, 2001
- Author:
CopyrightCOPYRIGHT 2001 Gardner Publications, Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Polarized Zinc Anodes
Q. Our shop uses an alkaline, non-cyanide zinc plating bath. We have an on-going problem with the anodes polarizing. What are we doing wrong? M.J.
A. High anode current density and/or low sodium hydroxide usually cause polarization of zinc anodes. The alkaline zinc plating bath has higher anode efficiency than cathode efficiency. This means that if you maintain a 1:1 anode-cathode ratio the amount of zinc in the plating bath will climb. The standard solution to this problem is to remove some of the zinc anodes. This causes the anode current density to climb and the anode will polarize unless the removed zinc anodes are replaced with ...