Atomic layer deposited thin films for corrosion protection

The suitability of Atomic Layer Deposition for making corrosion protection coatings was examined. Thin films of Al 2 O 3 , TiO 2 , Ta 2 O 5 and Al 2 O 3 -TiO 2 multilayers 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. Al 2 O 3 was found to protect the substrate material against corrosion for a limited time in NaCl. TiO 2 alone does not give good protection, but when combined with Al 2 O 3 in a multilayer structure better protection is achieved. Ta 2 O 5 films were tested in HCl and were found to protect the base material to some extent.