Effect of ZrO2 on corrosion behaviour of chromium coatings

To study the effect of ZrO2 particles on corrosion behaviour of Cr coating, steel samples were plated in Cr(VI) baths without and with ZrO2. The corrosion behaviour of plated samples was studied at different exposure times in a solution containing 0.01 mol l(-1) H2SO4 + 0.5 mol l(-1) Na2SO4 using cyclic voltammetry and impedance spectroscopy. The equivalent circuit model R-e(Q(c)R(pore))(Q(s)[ORs]) was proposed to fit the corrosion process and the parameters Y-0(Q(c)), Y-0(Q(s)) and R-pore reflecting corrosion behaviour of samples were evaluated. From the results, it was found that samples plated in bath containing ZrO2 exhibited improved protective properties as a result of the structural characteristics of the coatings obtained; namely, the size and shape of pores. (C) 2007 Elsevier Ltd. All rights reserved.