title: Effect of an amorphous titania nanotubes coating on the fatigue and corrosion behaviors of the biomedical Ti-6Al-4V and Ti-6Al-7Nb alloys.
abstract: An array of self-organized TiO2nanotubes with an amorphous structure was produced on the biomedical Ti-6Al-4V and Ti-6Al-7Nb alloys, and the resulting fatigue and corrosion behaviors were studied. The electrochemical response of the nanotubular oxide surfaces was investigated in Ringer physiological solution through potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The absence of transpassivation in the chloride-containing solution, in addition to the micron-scale values of the passivation current density, indicated the excellent corrosion behavior of the coating and the satisfactory protection against the creation of potential stress concentrators in the surface. Axial fatigue tests were performed in physiological solution on polished and coated conditions, with characterization of the treated surfaces by scanning electron microscopy before and after the tests. The surface modification was not deleterious to the fatigue response of both alloys mainly due to the nano-scale dimension of the nanotubes layer. An estimation based on fracture mechanics revealed that a circumferential crack in the range of 5μm depth would be necessary to affect the fatigue performance, which is far from the thickness of the studied coating, although no cracks were actually observed in the oxide surfaces after the tests.
authors.affiliation: Federal University of São Carlos, Department of Materials Engineering, Rod. Washington Luiz km. 235, 13565-905 São Carlos, SP, Brazil. Electronic address: leoccampa@hotmail.com.
authors.forename: Leonardo Contri
authors.initials: LC
authors.lastname: Campanelli
authors.affiliation: Federal University of São Carlos, Department of Materials Engineering, Rod. Washington Luiz km. 235, 13565-905 São Carlos, SP, Brazil.
authors.forename: Carolina Catanio
authors.initials: CC
authors.lastname: Bortolan
authors.affiliation: Federal University of São Carlos, Department of Materials Engineering, Rod. Washington Luiz km. 235, 13565-905 São Carlos, SP, Brazil.
authors.forename: Paulo Sergio Carvalho Pereira
authors.initials: PSCP
authors.lastname: da Silva
authors.affiliation: Federal University of São Carlos, Department of Materials Engineering, Rod. Washington Luiz km. 235, 13565-905 São Carlos, SP, Brazil.
authors.forename: Claudemiro
authors.initials: C
authors.lastname: Bolfarini
authors.affiliation: Federal University of São Carlos, Department of Materials Engineering, Rod. Washington Luiz km. 235, 13565-905 São Carlos, SP, Brazil.
authors.forename: Nilson Tadeu Camarinho
authors.initials: NTC
authors.lastname: Oliveira
mesh_terms: D000497:Alloys; D003343:Corrosion; D008422:Materials Testing; D043942:Nanotubes / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000032:analysis*
chemical_list: D000497:Alloys; C070282:Ti-6Al-7Nb alloy; C031462:titanium alloy (TiAl6V4); C009495:titanium dioxide; D014025:Titanium
keywords: Corrosion; Fatigue; Nanotubes; Surface modification; Titanium alloys