Transformation of porous structure of anodic alumina films formed during galvanostatic anodising of aluminium

Patermarakis, G; Moussoutzanis, K

dc.contributor.author	Patermarakis, G	en
dc.contributor.author	Moussoutzanis, K	en
dc.date.accessioned	2014-03-01T01:37:30Z
dc.date.available	2014-03-01T01:37:30Z
dc.date.issued	2011	en
dc.identifier.issn	1572-6657	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/21526
dc.subject	Galvanostatic Al oxidation	en
dc.subject	Porous films	en
dc.subject	Proportionality rule	en
dc.subject	Structure transformation	en
dc.subject.classification	Chemistry, Analytical	en
dc.subject.classification	Electrochemistry	en
dc.subject.other	Anodic alumina film	en
dc.subject.other	Anodic potentials	en
dc.subject.other	Anodising	en
dc.subject.other	Average field	en
dc.subject.other	Average size	en
dc.subject.other	Barrier layer thickness	en
dc.subject.other	Barrier layers	en
dc.subject.other	Base diameter	en
dc.subject.other	Cell width	en
dc.subject.other	Film surfaces	en
dc.subject.other	Galvanostatic Al oxidation	en
dc.subject.other	Galvanostatics	en
dc.subject.other	Growth of films	en
dc.subject.other	Porous anodic alumina films	en
dc.subject.other	Porous films	en
dc.subject.other	Porous structures	en
dc.subject.other	Proportionality rule	en
dc.subject.other	Steady state	en
dc.subject.other	Structural feature	en
dc.subject.other	Structure transformation	en
dc.subject.other	Surface density	en
dc.subject.other	Transient stage	en
dc.subject.other	Transport number	en
dc.subject.other	Alumina	en
dc.subject.other	Aluminum	en
dc.subject.other	Aluminum sheet	en
dc.subject.other	Chemical attack	en
dc.subject.other	Electrolytes	en
dc.subject.other	Surface structure	en
dc.title	Transformation of porous structure of anodic alumina films formed during galvanostatic anodising of aluminium	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.jelechem.2011.05.023	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.jelechem.2011.05.023	en
heal.language	English	en
heal.publicationDate	2011	en
heal.abstract	A method was developed revealing even slight variations of structural features around the barrier layer of porous anodic alumina films formed in H2SO4 electrolyte at conditions different from those of best ordering. This is based on the combination of a suitable structural-kinetic model with the average size of imprints of barrier layer units on the Al surface determined by FESEM. The galvanostatic growth of films in steady state is accompanied by rise of anodic potential with time depending on temperature. Simultaneously structural features around the barrier layer like cell width, pore base diameter and barrier layer thickness increase with time and anodic potential. The ratios of their values remain constant in time but depend on temperature. A proportionality rule thus applies explained by demand for constant Al3+ and O2- transport numbers in steady state. The enlargement of the above structural features occurs simultaneously with termination of some pores due to their narrowing resulting from drop of ionic conductance in pores and/or barrier layer. The surface density of cells/pores across the film increases to film surface. where it becomes highest, established around the start of second transient stage. The porosity near barrier layer remains constant with time but increases with temperature. The anodising ratio and average field strength across the barrier layer generally slightly increases and decreases respectively with time while the relevant trends are affected by temperature. FESEM examination of film surfaces showed structure affected by metallurgical texture, altered however to deeper layers, and surface structure changes due to chemical attack of oxide by the electrolyte. (C) 2011 Elsevier B.V. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE SA	en
heal.journalName	Journal of Electroanalytical Chemistry	en
dc.identifier.doi	10.1016/j.jelechem.2011.05.023	en
dc.identifier.isi	ISI:000293481700008	en
dc.identifier.volume	659	en
dc.identifier.issue	2	en
dc.identifier.spage	176	en
dc.identifier.epage	190	en