Multilayered polypyrrole–SiO2 composite coatings for functionalization of stainless steel: Characterization and corrosion protection behavior

• Two different multilayered composite polypyrrole/SiO2 coatings were elaborated.
• Electrophoretic approach allowed important incorporation of SiO2 into coatings.
• The coatings were characterized by GDOES, SEM and electrochemistry.
• SiO2 particles improved anti-corrosion behavior of the coatings.
• Best results were obtained when SiO2 is deposited directly on steel surface.

Two different multilayered composite polypyrrole/SiO2 coatings were synthesized on 304 stainless steel. Electrochemical and electrophoretic depositions were used to grow polypyrrole and SiO2 layers, respectively. Coatings were characterized by glow discharge optical emission spectroscopy to observe repartition of elements within different layers, by scanning electron microscopy to observe surface morphology and by electrochemistry to investigate corrosion protection behavior. The electrophoretic approach enables good incorporation of SiO2 particles. This incorporation was more extensive and more homogeneous than for coatings obtained with the mixing method related in previous works. Moreover, incorporation and repartition of SiO2 particles are greatly enhanced when the silica layer is grown directly on the steel surface. Corrosion protection of the stainless steel substrate was improved when multilayered composite polypyrrole/SiO2 coatings were used.