Corrosion properties of ion beam modified fullerene thin films on iron substrates

The corrosion behavior of fullerene coated iron samples was investigated by using electrochemical techniques. Fullerene was deposited on iron substrates via thermal evaporation under high vacuum conditions. Subsequent sample preparation included heat treatment as well as Ar+ ion irradiation under various conditions, which were carried out to modify the fullerene coatings. Changes in the structure of the films due to the treatment were analyzed by Raman spectroscopy. To reveal the samples’ corrosion behavior, cyclovoltammetric measurements were performed in a weakly acidic aqueous medium particularly with regard to possible corrosion protective properties. As the results show, Ar-ion treatment of the fullerene films leads to considerably increased corrosion resistance, which is due to formation of a dense amorphous carbon network. In contrast, heat treatment of the fullerene films increases the corrosion rates, presumably due to formation of iron carbide, which leads to galvanic corrosion.