Preparation of plasma-polymerized SiOx-like thin films from a mixture of hexamethyldisiloxane and oxygen to improve the corrosion behaviour

Chemical and electrochemical properties of plasma polymerized SiOx-like thin films have been studied to search for an alternative to the anticorrosive coatings produced by chromate conversion treatment. The films were deposited on steel substrates by means of hexamethydisiloxane/oxygen-fed plasmas ignited in an RF capacitive coupled parallel plates reactor. Their surface chemical characterization was carried out by means of X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FT-IR). The protective abilities of SiOx-like films as a function of RF power and gas feed composition in aerated 1 M Na2SO4 solution were examined by electrochemical methods. Alone and in combination, these techniques help us to understand the relationship between the deposition parameters and the properties of the deposited films.