Investigation of anticorrosive trivalent-chrome coatings on 6063 aluminum alloy

摘要

In this work, Chromium (Cr(III)) conversion coatings on Al 6063 alloy was prepared using trivalent-chrome compound (KCr(SO_4)_2) and H_3PO_4. The influence of five variables (i.e. deposition temperature, time, bath pH, and concentrations of (Cr(III)) compound (KCr(SO_4)_2) and H_3PO_4) on the preparation of (Cr(III)) coating on Al 6063 alloy was investigated using polarization curve in 3.5 wt% NaCl solution. The parameters of polarization curves were obtained from the extrapolation of anodic and cathodic Tafel lines. The optimum chemical passivation parameters of the chromium (Cr((UI)) conversion coatings on the 6063 Al surface were obtained in this paper The results show the chromium (Cr(III)) conversion coatings formed under the optimal range present better corrosion resistance than those under the other conditions. Proper mechanisms were proposed to explain the above electrochemical behavior for the five treated conditions.