Electrochemical kinetic study on the growth of porous anodic oxide films on aluminium

Patermarakis, G; Moussoutzanis, K

dc.contributor.author	Patermarakis, G	en
dc.contributor.author	Moussoutzanis, K	en
dc.date.accessioned	2014-03-01T01:10:57Z
dc.date.available	2014-03-01T01:10:57Z
dc.date.issued	1995	en
dc.identifier.issn	0013-4686	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/11514
dc.subject	aluminium	en
dc.subject	anodizing	en
dc.subject	electrochemical kinetics	en
dc.subject	growth	en
dc.subject	oxide	en
dc.subject	porous	en
dc.subject.classification	Electrochemistry	en
dc.subject.other	AL2O3 FILMS	en
dc.subject.other	TRANSPORT NUMBERS	en
dc.subject.other	HYDROTHERMAL TREATMENT	en
dc.subject.other	PASSIVE FILMS	en
dc.subject.other	PORE CLOSURE	en
dc.subject.other	AL METAL	en
dc.subject.other	OXIDATION	en
dc.subject.other	MECHANISM	en
dc.subject.other	HYDRATION	en
dc.subject.other	OXYGEN	en
dc.title	Electrochemical kinetic study on the growth of porous anodic oxide films on aluminium	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/0013-4686(94)00347-4	en
heal.identifier.secondary	http://dx.doi.org/10.1016/0013-4686(94)00347-4	en
heal.language	English	en
heal.publicationDate	1995	en
heal.abstract	Aluminium specimens were anodized galvanostatically in a thermostated and vigorously stirred bath of H2SO4 15% w/v at different bath temperatures and current densities and for long anodization times, sufficient to produce the maximum or near maximum limiting film thickness, and the anodic potential was followed. Results confirmed that the rate controlling step of the steady-state growth of the barrier layer is the charge transport across this layer, which is near solely due to the migration of anions; oxide is produced only in a region adjacent to the Al-Al2O3 interface. Taking into consideration the structural features of the barrier layer oxide and by assuming a uniform oxide nature and one kind of migrating anions or cations, it has become possible to formulate simplified high field ion migration electrochemical kinetic equations. They were found to be non-satisfactory when applied at low anodization temperatures, but become applicable at high temperatures or low barrier layer thicknesses. Their application postulated that the charge transfer at the Al-Al2O3 interface, Al-3e → Al3+, takes place rather through successive ""one electron"" transfer elementary steps. Also, the charge transport across the barrier layer oxide bulk takes place through a concomitant migration of the ions O2-, OH- and SO42- . A model for the ions transport was suggested which gives a physical meaning to the field assisted oxide dissolution at pore bases, explains the incorporation of SO42-, SO3, OH- and H2O and predicts the change of their concentration, of the oxide nature and of the values of kinetic parameters across the barrier layer; it also predicts that an H+ migration may take place during oxide growth. © 1995.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Electrochimica Acta	en
dc.identifier.doi	10.1016/0013-4686(94)00347-4	en
dc.identifier.isi	ISI:A1995QX23500005	en
dc.identifier.volume	40	en
dc.identifier.issue	6	en
dc.identifier.spage	699	en
dc.identifier.epage	708	en