Conversion Coating Treatment for Zinc Surface by a Vanadate Solution

Abstract

In this work, chemical conversion coating on zinc surfaces was performed by immersion in a solution containing vanadate. Corrosion behaviour of zinc surfaces was investigated using electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. According to the results, the vanadium-treated layer significantly improved the corrosion resistance of zinc surfaces in contact with 3.5 % NaCl solution. In comparison of the chromium-treated layer, the vanadium-treated layer also exhibits better corrosion resistance. The treated zinc surface mainly consists of vanadium and oxygen, which mainly exist as V₂O₅, VO₂, and its hydrates.