Hexavalent chromium determination on anti-corrosion zinc based coatings

This work aims to study methodologies used to quantitatively dose the hexavalent chromium content in zinc plated passivation, due to the necessity imposed by the European Directive 2000/53/CE to control the specimen's presence in automotive applications. The known methodology, by means of reaction with 1,5-diphenylcarbazide in aqueous solutions, gives good results. Nevertheless, its application imposes the construction of a reliable methodology for the chromium VI extraction from the treated surface, challenge up to now not overcome. It was studied the kinetics of warmed aqueous extraction of the hexavalente chromium present in the passivation, besides the smooth alkali and acid digestions proposed in this work.