Kinetics of growth of porous anodic Al2O3 films on A1 metal

Patermarakis, G; Lenas, P; Karavassilis, Ch; Papayiannis, G

dc.contributor.author	Patermarakis, G	en
dc.contributor.author	Lenas, P	en
dc.contributor.author	Karavassilis, Ch	en
dc.contributor.author	Papayiannis, G	en
dc.date.accessioned	2014-03-01T01:08:24Z
dc.date.available	2014-03-01T01:08:24Z
dc.date.issued	1991	en
dc.identifier.issn	0013-4686	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/10471
dc.subject	aluminium	en
dc.subject	anodizing	en
dc.subject	growth	en
dc.subject	kinetics	en
dc.subject	oxide	en
dc.subject	porous	en
dc.subject.classification	Electrochemistry	en
dc.subject.other	ALUMINUM	en
dc.title	Kinetics of growth of porous anodic Al2O3 films on A1 metal	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/0013-4686(91)85162-Z	en
heal.identifier.secondary	http://dx.doi.org/10.1016/0013-4686(91)85162-Z	en
heal.language	English	en
heal.publicationDate	1991	en
heal.abstract	The kinetics of growth of porous anodic aluminium oxide films on Al metal, anodized galvanostatically in a non-stirred bath solution 15% w/v H2SO4 at various current densities (5-75 mA/cm2) and bath temperatures (20-40-degrees-C), were studied. The model m = kit - lambda-1t exp (lambda-2t) was found to be valid for all the anodization conditions chosen and for anodization time intervals shorter than those beyond which limiting constant values of film mass and thickness are obtained. The model shows that the true shape of pores is that of a trucated cone, whereas parameters lambda-1 and lambda-2 are directly related to the surface area of the pore base section (lambda-1 = 4(-1) kin-pi-D0(2)) and the dissolution rate of pore wall oxide (lambda-2 = 2k(d)D0(-1)). With the aid of the model it was proven that, during anodization, oxide dissolution at the depth of pores is essentially a field-assisted process; while pore wall oxide dissolution is a first-order reaction, thermally activated, with an activation energy of 78.6 kJ/mol; electrolyte concentration inside the pores increases linearly with true current density (C = C0 + ai(t)). The open circuit oxide dissolution rate was found to be 0.52-4.1 angstrom/min for anodization temperatures of 20-40-degrees-C. Also, by applying the model, information was obtained on the oxide's main structural characteristics such as concentration of cells and pores, cell mean width, pore base mean diameter, thickness of barrier layer, total and specific real surface, porosity, etc.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Electrochimica Acta	en
dc.identifier.doi	10.1016/0013-4686(91)85162-Z	en
dc.identifier.isi	ISI:A1991FC88600044	en
dc.identifier.volume	36	en
dc.identifier.issue	3-4	en
dc.identifier.spage	709	en
dc.identifier.epage	725	en