Study of the anticorrosive properties of different bi-Layers of polypyrrole - BTSE on carbon steel immersed in NaCl media

To improve the corrosion resistance of mild steel, in this work, bi-layers of BTSE (bis-(triethoxysilyl) ethane) and Ppy coatings have been deposited via adsorption and electrodeposition, respectively. The anticorrosive properties of these bi-layers have been evaluated in an aggressive medium like 3% NaCl, and compared with the layers of BTSE and Ppy in a separate way. In spite of the aggressive solution, it was evaluated a poor behaviour of both Ppy and BTSE coatings using potential measurements, EIS and SEM techniques. A better behaviour was expected because the preparation of the bilayers Ppy/BTSE and BTSE/Ppy showed a protective behaviour using SEM and salt spray tests. However, EIS results predicted an evolution of these coatings for long immersion times being evident the oxidation of the steel.