title: Growth of aluminum-free porous oxide layers on titanium and its alloys Ti-6Al-4V and Ti-6Al-7Nb by micro-arc oxidation.
abstract: The growth of oxides on the surfaces of pure Ti and two of its ternary alloys, Ti-6Al-4V and Ti-6Al-7Nb, by micro-arc oxidation (MAO) in a pH 5 phosphate buffer was investigated. The primary aim was to form thick, porous, and aluminum-free oxide layers, because these characteristics favor bonding between bone and metal when the latter is implanted in the human body. On Ti, Ti-6Al-4 V, and Ti-6Al-7Nb, the oxides exhibited breakdown potentials of about 200 V, 130 V, and 140 V, respectively, indicating that the oxide formed on the pure metal is the most stable. The use of the MAO procedure led to the formation of highly porous oxides, with a uniform distribution of pores; the pores varied in size, depending on the anodizing applied voltage and time. Irrespective of the material being anodized, Raman analyses allowed us to determine that the oxide films consisted mainly of the anatase phase of TiO2, and XPS results indicated that this oxide is free of Al and any other alloying element.
authors.affiliation: Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Caixa Postal 676, 13560-970 São Carlos, SP, Brazil. Electronic address: laisduar@yahoo.com.br.
authors.forename: Laís T
authors.initials: LT
authors.lastname: Duarte
authors.affiliation: Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Caixa Postal 676, 13560-970 São Carlos, SP, Brazil.
authors.forename: Claudemiro
authors.initials: C
authors.lastname: Bolfarini
authors.affiliation: Departamento de Química, Universidade Federal de São Carlos, Caixa Postal 676, 13560-970 São Carlos, SP, Brazil.
authors.forename: Sonia R
authors.initials: SR
authors.lastname: Biaggio
authors.affiliation: Departamento de Química, Universidade Federal de São Carlos, Caixa Postal 676, 13560-970 São Carlos, SP, Brazil.
authors.forename: Romeu C
authors.initials: RC
authors.lastname: Rocha-Filho
authors.affiliation: Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Caixa Postal 676, 13560-970 São Carlos, SP, Brazil.
authors.forename: Pedro A P
authors.initials: PA
authors.lastname: Nascente
mesh_terms: D000497:Alloys; D000535:Aluminum / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry; D018786:Bone Substitutes / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D016062:Porosity; D013059:Spectrum Analysis, Raman; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D018786:Bone Substitutes; D010087:Oxides; C070282:Ti-6Al-7Nb alloy; C031462:titanium alloy (TiAl6V4); C009495:titanium dioxide; D000535:Aluminum; D014025:Titanium
keywords: MAO anodizing process; Porous oxides on biomaterials; Titanium alloy anodization; Titanium anodization