Application of Scanning Vibrating Electrode Technique for Evaluation of Chemical Surface Treatment on Zinc Coated Steel Sheets

Abstract

Using a scanning vibrating electrode technique (SVET), corrosion current distributions in a dilute sodium chloride solution were measured for chemically treated surfaces of two type of the zinc coated steel sheets (hot-dip galvanized and zinc vapor deposited steel sheets).
The following results were obtained.
(1)The zinc coated steel sheets with a normal dip-chromating film after painting exhibited excellent paint film adhesion and satisfactory corrosion resistance at cut edges, when anodic current was not detected by SVET over the entire surface of the zinc coated steel sheets after the suitable alkaline surface conditioning treatment and flash chromating.
(2)The SVET system with a electromagnetic loud speaker unit for vibration proved useful to evaluate the chemically treated film on the zinc coated steel sheet.