Electroplated bright aluminium coatings for anticorrosion and decorative purposes

This paper is dedicated to the study of electrodeposited aluminium layers as anticorrosion protective coatings on metallic substrates. The aim of this approach is to propose a non-toxic alternative to the traditional nickel-chromium coating, for anticorrosive and decorative purposes. Aluminium was electrodeposited on carbon steel substrates from chloroaluminate based ionic liquids with and without the addition of 1,10-phenantroline. In the first case, the Al deposits are dense but dull, while in the latter homogeneous and bright coatings suitable for decorative purposes were achieved. The corrosion properties of carbon steel coated with bright and dull Al coating were evaluated by means of electrochemical techniques (open circuit potential and potentiodynamic polarization curves) and free corrosion tests, carried out in a salt-spray cabinet on Al and Ni-Cr plated car wheel bolts. According to these tests, we found the Al coating provides nearly the same corrosion resistance as the Ni-Cr, with the advantage to being totally free of harmful metals. (C) 2009 Elsevier B.V. All rights reserved.