Atomic layer deposited thin films for corrosion protection

The suitability of Atomic Layer Deposition for making corrosion protection coatings was examined. Thin films of Al2O3, TiO2, Ta2O5 and Al2O3-TiO2 multilayer were deposited on stainless steel substrates. The films were deposited at 150-400 °C. The corrosion behaviour of the samples was studied by Electrochemical Impedance Spectroscopy in 3.5 wt.% NaCl and 0.1 and 1 mol/l HCl solutions. Al2O3 was found to protect the substrate material against corrosion for a limited time in NaCl. TiO2 alone does not give good protection, but when combined with Al2O3 in a multilayer structure better protection is achieved. Ta2O5 films were tested in HCl and were found to protect the base material to some extent