Effects of substrate microstructure on the formation of oriented oxide nanotube arrays on Ti and Ti alloys

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dc.contributor.authorFerreira, C. P.
dc.contributor.authorGoncalves, M. C.
dc.contributor.authorCaram, R.
dc.contributor.authorBertazzoli, R.
dc.contributor.authorRodrigues, C. A. [UNIFESP]
dc.contributor.institutionUniversidade Estadual de Campinas (UNICAMP)
dc.contributor.institutionUniversidade Federal de São Paulo (UNIFESP)
dc.date.accessioned2016-01-24T14:34:43Z
dc.date.available2016-01-24T14:34:43Z
dc.date.issued2013-11-15
dc.description.abstractThe formation of nanotubular oxide layers on Ti and Ti alloys has been widely investigated for the photocatalytic degradation of organic compounds due to their excellent catalytic efficiency, chemical stability, and low cost and toxicity. Aiming to improve the photocatalytic efficiency of this nanostructured oxide, this work investigated the influence of substrate grain size on the growth of nanotubular oxide layers. Ti and Ti alloys (Ti-6A1, Ti-6A1-7Nb) were produced by arc melting with non-consumable tungsten electrode and water-cooled copper hearth under argon atmosphere. Some of the ingots were heat-treated at 1000 C for 12 and 24 h in argon atmosphere, followed by slow cooling rates to reduce crystalline defects and increase the grain size of their microstructures. Three types of samples were anodized: commercial substrate, as-prepared and heat-treated samples. the anodization was performed using fluoride solution and a cell potential of 20V. the samples were characterized by optical microscopy, field-emission scanning electron microscopy and X-ray diffraction. the heat treatment preceding the anodization process increased the grain size of pure Ti and Ti alloys and promoted the formation of Widmanstatten structures in Ti6A17Nb. the nanotubes layers grown on smaller grain and thermally untreated samples were more regular and homogeneous. in the case of Ti-6A1-7Nb alloy, which presents a ce.+ p phase microstructure, the morphology of nanotubes nucleated on ce. matrix was more regular than those of nanotubes nucleated on p phase. After the annealing process, the Ti-6A1-7Nb alloy presented full diffusion process and the growth of equilibrium phases resulting in the appearance of regions containing higher concentrations of Nb, i.e. beta phase. in those regions the dissolution rate of Nb205 is lower than that of Ti02, resulting in a nanoporous layer. in general, heat treating reduces crystalline defects and promotes the increasing of the grain sizes, not favoring the process of nanotube nucleation and growth on the metallic surface. (C) 2013 Elsevier B.V. All rights reserved.en
dc.description.affiliationState Univ Campinas Unicamp, Dept Mat Engn Dema FEM, BR-13083970 Campinas, SP, Brazil
dc.description.affiliationState Univ Campinas Unicamp, Inst Quim, BR-13083970 Campinas, SP, Brazil
dc.description.affiliationUniversidade Federal de São Paulo, Dept Ciencias Exatas & Terra, BR-09913030 Diadema, SP, Brazil
dc.description.affiliationUnifespUniversidade Federal de São Paulo, Dept Ciencias Exatas & Terra, BR-09913030 Diadema, SP, Brazil
dc.description.sourceWeb of Science
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorshipIDFAPESP: 2006/61261-2
dc.format.extent226-234
dc.identifierhttp://dx.doi.org/10.1016/j.apsusc.2013.08.041
dc.identifier.citationApplied Surface Science. Amsterdam: Elsevier B.V., v. 285, p. 226-234, 2013.
dc.identifier.doi10.1016/j.apsusc.2013.08.041
dc.identifier.issn0169-4332
dc.identifier.urihttp://repositorio.unifesp.br/handle/11600/36980
dc.identifier.wosWOS:000326579400021
dc.language.isoeng
dc.publisherElsevier B.V.
dc.relation.ispartofApplied Surface Science
dc.rightsinfo:eu-repo/semantics/restrictedAccess
dc.rights.licensehttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dc.subjectTiO2 nanotubesen
dc.subjectTi alloysen
dc.subjectTi alloys anodizationen
dc.titleEffects of substrate microstructure on the formation of oriented oxide nanotube arrays on Ti and Ti alloysen
dc.typeinfo:eu-repo/semantics/article
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