Characteristics and lacquer adhesion on dip and CDC chromium passivated tinplate

Chromium passivation and lacquering are typically used to improve the corrosion resistance of tinplate in packed food. In this work, the nature of the chromium passivation layer formed during dip or CDC passivation treatments, as a function of operational parameters, and its influence on lacquer adhesion, was investigated using electrochemical polarisation, XPS, Auger and lacquer peel-off tests. It was found that dip passivated tinplate provide the best lacquer adhesion, and that the adhesion on CDC treated tinplate could be improved by buffering or lowering the pH of the chromium (VI) solution.