Résumé:
The objective of this work is focused on the development of two different methods of surface treatment by plasma for improved anticorrosive properties of hard carbon steel (C75) in 0.5 M NaCl medium airy. The first method involves the polymerization of Tetramethyldisiloxane (TMDSO) in admixture with oxygen by cold nitrogen post-discharge plasma. The properties of the polysiloxane coating obtained can be modified in situ by a post-treatment by nitrogen plasma in a mixture with oxygen; it can be inserted into or outside of the discharge. This potential has led to the development of multilayer materials. The effectiveness of such coatings with respect to corrosion was evaluated by impedance and electrochemical measurements in 0.5 M NaCl medium airy. The results show that the effectiveness of these coatings increases with the number of intermediate layers and is strongly dependent on the injection of oxygen at the stage of post-treatment plasma polymer. Analysis by FTIR, XPS and TOF-SIMS clearly demonstrate cross-linking of post-treated coating which leads to a sharp increase in the resistance of pores. The influence of surface preparation and content of oxygen mixed with TMDSO were also studied. The second method involves exposing the surface to a humid air plasma type ‘glidarc (gliding arc discharge: GAD) for different exposure times, the effectiveness of the method has been tested using gravimetric methods electrochemical. The results show a reduction in corrosion rate, a increase of the corrosion potential value, and a decrease in the intensity of the corrosion current, showing the formation of a passivating layer on the treated surface. A comparative study with a chemical inhibitor type Benzotriazole (1H-BTA ) showed that 60 min plasma treatment GAD replace a concentration of 10 mM 1H-BTA and leads to an inhibition efficiency of about 75 %. This result demonstrates the effectiveness and potential use of plasma GAD are unpolluted and inexpensive to implement technologies.
