Characterisation and corrosion protection properties of polypyrrole electropolymerised onto aluminium in the presence of molybdate and nitrate

This paper describes the first attempts for the electrosynthesis of polypyrrole films containing molybdate onto aluminium electrodes. Electrogeneration was carried out in an alkaline solution in the presence of molybdate, nitrate and the monomer. The optimum concentrations for electropolymerisation were chosen in order to improve the corrosion protection of the substrate. The coatings were characterised by SEM/EDX and IR spectroscopy and the cyclic voltammetric response of the film is discussed. Pitting corrosion resistance was studied by means of open circuit potential and potentiodynamic measurements. The results presented below show that molybdate remains entrapped into the polymer matrix, providing greater resistance to breakdown of passivity in chloride media.