Abstract:

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.

Author affiliation: Flamini, Daniel Omar. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto Ingenieria Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Saugo, Melisa. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto Ingenieria Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Saidman, Silvana Beatriz. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto Ingenieria Electroquímica y Corrosión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Abstract:

Polypyrrole (PPy) films were electrodeposited onto nickel--titanium alloy (NiTi) employing sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol OT or AOT) solutions. Polarizing anodically NiTi samples recovered by PPy in a monomer-free solution increases adhesion of the coating. Electrochemical techniques, scanning electron microscopy (SEM) and element analysis were used in determining the corrosion performance of the coated samples in chloride solution. The polymer improves the corrosion performance at the open circuit potential and at potentials where the bare substrate suffers pitting attack. The improvement in both, adhesion and corrosion performance, is discussed considering substrate/polymer interaction, overoxidation of PPy and the role played by AOT. © 2009 Elsevier Ltd. All rights reserved.

Author affiliation: Flamini, Daniel Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina

Author affiliation: Saidman, Silvana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Ingeniería Electroquímica y Corrosión; Argentina