Electrodeposition of polypyrrole on 316L stainless steel for corrosion prevention

The electrosynthesis of polypyrrole films onto 316L stainless steel from near neutral and alkaline solutions containing molybdate and nitrate is reported. The corrosion behavior of the coated electrodes was investigated in NaCl solutions by electrochemical techniques and scanning electron microscopy. The polymer formed potentiostatically in a solution of pH 12 is the most efficient in terms of adhesion and corrosion protection. The coating significantly reduces the pitting corrosion of the substrate. The results are interpreted in terms of the nature of dopants, the good electroactivity of the polymer formed in alkaline solution and the passivating properties of the oxide layer.

Research highlights
► PPy films were electrodeposited on 316L SS in solutions containing MoO42- and/or NO3-.
► The coatings completely inhibit pitting corrosion in chloride solutions.
► At pH 12, the PPy is electroactive and the oxide film is more stable.
► The more protective films were obtained in presence of MoO42- and NO3- at pH 12.