Deposition of SiOx-Like Thin Films from a Mixture of HMDSO and Oxygen by Low Pressure and DBD Discharges to Improve the Corrosion Behaviour of Steel

Hexamethyldisiloxane was used to deposit silicon dioxide thin films using a low frequency plasma reactor at low pressure as well as a dielectric barrier discharge (DBD) at atmospheric pressure. FT-IR, XPS, EIS, SEM and ellipsometry were used to analyse the samples. The results show that, at low pressure, the deposited films which are smooth, continuous and dense present a polymer-like structure. By carrying out the film deposition after an oxygen plasma pretreatment step, a further improvement in the protective properties is achieved, which is observed in the case of SiOx coatings with 13.56 MHz RF generators.([1]) At atmospheric pressure, the deposited films present an inorganic character deposited in open air and a polymer-like one deposited under a controlled nitrogen atmosphere in our DBD reactor. The latter also allows continuous films which present the best anti-corrosive properties (which have been studied for the first time for anti-corrosive properties) when they contain some carbon incorporated.