Electrodeposition of polypyrrole on Nitinol alloy in the presence of inhibitor ions for corrosion protection

• Polypyrrole was electrodeposited on Nitinol using different corrosion inhibitors.
• The most protective polypyrrole films were obtained with NO3- and MoO42- at pH 12.
• The coating inhibits the pitting corrosion of the substrate in chloride solution.
• The degree of corrosion protection is related to the good adhesion of the film.

The electrosynthesis of polypyrrole (PPy) films on Nitinol (NiTi) from solutions containing different corrosion inhibitors is reported. The corrosion behaviour of the coated samples was investigated in 0.15 M NaCl solution. The presence of molybdate ions in the polymer matrix confers to the substrate a greater resistance to pitting corrosion. The polymer formed potentiostatically in a solution at pH 12 containing nitrate and molybdate is the most efficient in terms of adhesion and corrosion protection. Results are interpreted in terms of the nature of the dopants, the good electroactivity of the polymer and passive properties of the oxide layer.