Polypyrrole coating doped with dihydrogenophosphate ion to protect aluminium against corrosion in sodium chloride medium

Abstract

A electrodeposição do polipirrole (PPy) sobre alumínio em soluções de ácido fosfórico foi obtida através de técnicas potenciodinâmicas, potenciostáticas e galvanostáticas. O comportamento do alumínio revestido com polipirrole em meio de cloreto de sódio foi investigado através do potencial de circuito aberto e espectroscopia de impedância electroquímica. É proposto um mecanismo para explicar o efeito benéfico do íon dihidrogenofosfato na passivação do alumínio.The electrodeposition of polypyrrole (PPy) on aluminium electrodes has been achieved in phosphoric acid medium by using potentiodynamic, potentiostatic and galvanostatic techniques. The corrosion behavior of polypyrrole on aluminium in sodium chloride medium has been investigated by open circuit potential and electrochemical impedance spectroscopy. A mechanism to explain the beneficial effect of PPy-doping dihydrogenophosphate ion in the passivation of aluminium is proposed.

Corrosion protection of stainless steel plates in fuel cells environment by conducting polymers

“…Recently, a broader concept based on anion‐exchange capacity was proposed . The released anions, from polymer reduction induced by corrosion at metal defect or by concentration gradient, may act as inhibitors.…”

Electrochemical and spectroscopical studies of polypyrrole synthesized on carbon steel from aqueous medium

“…We showed in our previous work that PPy coating prevents corrosion by isolation and charge transfer mechanism [18,19]. Recently, a broader concept based on anion-exchange through the polymer backbone structure was reported to explain metal passivation [20][21][22]. Kowalski et al [23] suggest a PPy bilayer coating for the carbon steel, which inner layer is doped with heteropolyanions of PMo 12 O 40 3À and HPO 42 À and the outer with dodecylsulfate ions CH 3 (CH 2 ) 11 OSO 3 À .…”