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Mono-carboxylate conversion coatings for AZ31 Mg alloy protection / A. Frignani in Materials and corrosion, Vol. 62 N° 11 (Novembre 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 11 (Novembre 2011) . - pp. 995–1002 Titre : Mono-carboxylate conversion coatings for AZ31 Mg alloy protection Type de document : texte imprimé Auteurs : A. Frignani, Auteur ; V. Grassi, Auteur ; F. Zucchi, Auteur Année de publication : 2012 Article en page(s) : pp. 995–1002 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : AZ31  Conversion  coating  Corrosion  Magnesium  alloy  Mono-carboxylic  acids Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Conversion coatings on a magnesium alloy were obtained by dipping AZ31 specimens in aqueous solutions of sodium salts of mono-carboxylic acids (stearic, palmitic, myristic, lauric, mono-carboxylate ion concentration from 1 to 5 mM, depending on the salt solubility) for 24 and 72 h at room temperature, or 24 h at 50 °C. The influence exerted by the treatment time, bath temperature and alkyl chain length on the efficiency of these coatings was studied. The performances of the coatings were evaluated by potentiodynamic polarization curve recording after 1 h immersion in 0.05 M Na2SO4 solution, while their temporal evolution was monitored by electrochemical impedance spectroscopy (EIS) spectra during 24 h. Further and long lasting tests were carried out also in 0.1 M NaCl solution. The efficiency of the coatings depended on the aliphatic chain length, and increased as the treatment time and the bath temperature were increased. The coating of lower homologue only hindered the cathodic process, while those of the higher homologues markedly inhibited the anodic process too. The best performances were displayed by 24 h-50°C stearic conversion coating, which maintained a very high efficiency for over 800 h immersion in 0.05 M sulphate solution. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905615/abstract [article] Mono-carboxylate conversion coatings for AZ31 Mg alloy protection [texte imprimé] / A. Frignani, Auteur ; V. Grassi, Auteur ; F. Zucchi, Auteur . - 2012 . - pp. 995–1002. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 11 (Novembre 2011) . - pp. 995–1002 Mots-clés : AZ31  Conversion  coating  Corrosion  Magnesium  alloy  Mono-carboxylic  acids Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Conversion coatings on a magnesium alloy were obtained by dipping AZ31 specimens in aqueous solutions of sodium salts of mono-carboxylic acids (stearic, palmitic, myristic, lauric, mono-carboxylate ion concentration from 1 to 5 mM, depending on the salt solubility) for 24 and 72 h at room temperature, or 24 h at 50 °C. The influence exerted by the treatment time, bath temperature and alkyl chain length on the efficiency of these coatings was studied. The performances of the coatings were evaluated by potentiodynamic polarization curve recording after 1 h immersion in 0.05 M Na2SO4 solution, while their temporal evolution was monitored by electrochemical impedance spectroscopy (EIS) spectra during 24 h. Further and long lasting tests were carried out also in 0.1 M NaCl solution. The efficiency of the coatings depended on the aliphatic chain length, and increased as the treatment time and the bath temperature were increased. The coating of lower homologue only hindered the cathodic process, while those of the higher homologues markedly inhibited the anodic process too. The best performances were displayed by 24 h-50°C stearic conversion coating, which maintained a very high efficiency for over 800 h immersion in 0.05 M sulphate solution. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905615/abstract