resumo
The production of polyaniline films on aluminium alloy 6061-T6 in sulphuric acid was carried out by electrodeposition, using cyclic voltammetry and potentiostatic polarization. The films obtained were characterized by SEM and XPS analysis. Electrochemical techniques were also used to assess the anticorrosive properties of the coatings. The choice of the upper potential limits for potential cycling and of the fixed potential for potentiostatic production should take in consideration the balance between their effect on the minimum number of cycles (or time) needed to produce the film and on the rate of overoxidation. Polarization curves show a slight increase of the corrosion potential for polyaniline coated substrate as compared with bare metal, indicating that no significant protection is achieved by the polymer coating. The Bode diagrams show low impedance values for the alloy covered with polyaniline when compared with the results obtained for the bare metal. This can be attributed to the conductive character of the polyaniline films. (C) 2009 Elsevier Ltd. All rights reserved.
palavras-chave
CORROSION PROTECTION; CONDUCTING POLYMERS; ELECTROCHEMICAL DEPOSITION; POLYPYRROLE COATINGS; NONFERROUS METALS; AQUEOUS-SOLUTION; FILMS; ELECTROPOLYMERIZATION; ELECTRODEPOSITION; IMPEDANCE
categoria
Electrochemistry
autores
Martins, NCT; Silva, TME; Montemor, MF; Fernandes, JCS; Ferreira, MGS
nossos autores
Mário Guerreiro Silva Ferreira
Professor(a) Jubilado(a)Projectos
Electropolymerised Coatings Used as Pre-Treatment for Aluminium Alloys (POCI/CTM/60064/2004)
agradecimentos
The authors acknowledge the Portuguese Science and Technology Foundation (FCT) for the financial support under the contracts POCI/CTM/60064/2004 and PPCDT/CTM/60064/2004.