Investigation of the incorporation of electrolyte anions in porous anodic AI2O3 films by employing a suitable probe catalytic reaction

Patermarakis, G; Moussoutzanis, K; Nikolopoulos, N

dc.contributor.author	Patermarakis, G	en
dc.contributor.author	Moussoutzanis, K	en
dc.contributor.author	Nikolopoulos, N	en
dc.date.accessioned	2014-03-01T01:14:44Z
dc.date.available	2014-03-01T01:14:44Z
dc.date.issued	1999	en
dc.identifier.issn	1432-8488	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/13209
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-0033415344&partnerID=40&md5=6d404546a6a893292817f4e3b02e6f2a	en
dc.subject	Aluminium	en
dc.subject	Anodizing	en
dc.subject	Electrolyte anions	en
dc.subject	Incorporation	en
dc.subject	Porous oxide	en
dc.subject.classification	Electrochemistry	en
dc.subject.other	OXIDE-FILMS	en
dc.subject.other	ALUMINUM	en
dc.subject.other	ANODIZATION	en
dc.subject.other	GROWTH	en
dc.subject.other	MECHANISM	en
dc.subject.other	MODELS	en
dc.title	Investigation of the incorporation of electrolyte anions in porous anodic AI2O3 films by employing a suitable probe catalytic reaction	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	1999	en
heal.abstract	A new method has been developed capable of describing the incorporation of electrolyte anions along the pore wall surface and across both the barrier layer and the pore wall oxide after the establishment of the steady state of growth of porous anodic Al2O3 where other methods cannot be applied to obtain reliable results. The knowledge of the nature/composition of anodic oxides as regards the incorporation of species like electrolyte anions is of specific importance for both the understanding of the electrochemical mechanism of oxide production and growth and the scientific and technological applications of porous anodic Al2O3 films. The method consists of the selection and use of a suitable catalytic probe reaction on porous anodic oxides at thicknesses varying from a value near zero up to the maximum limiting thickness and the treatment of the experimental reaction rate results by a properly developed mathematical formalism. This method was employed in anodic Al2O3 films prepared in H2SO4 anodizing electrolyte at a constant bath temperature and different current densities using as a probe reaction the decomposition of HCOOH on these oxides, which is almost exclusively a dehydration reaction, at relatively high reaction temperatures, 350 degrees C and 390 degrees C, where the effect of other species except SO43- incorporated in the oxide on the reaction rate is eliminated. It has been shown that the fraction of the intercrystallite surfaces occupied by SO43- follows a parabola-like distribution. It has a significant value at the pore base surface, depending on the current density, then it passes through a maximum along the pore wall surface and across both the barrier layer and the pore walls near the pore bases at positions depending on the current density and then becomes almost zero at the mouths of the pores of the oxide with the maximum limiting thickness and at both the Al2O3/Al interface and cell boundaries. The maximum value of the surface coverage is almost independent of the current density and is always near 1, showing an almost complete saturation of intercrystalline surfaces at these positions. The above distribution of surface coverage predicts a qualitatively similar distribution of the SO42- bulk concentration across both the barrier layer and pore wall oxide around the pore bases. The method may be improved and developed further either for a more detailed investigation of the above films or to investigate films prepared in other pore-forming electrolytes.	en
heal.publisher	SPRINGER VERLAG	en
heal.journalName	Journal of Solid State Electrochemistry	en
dc.identifier.isi	ISI:000080268600003	en
dc.identifier.volume	3	en
dc.identifier.issue	4	en
dc.identifier.spage	193	en
dc.identifier.epage	204	en