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Characterisation of anodic films formed on titanium and its alloys
Author(s) -
Mirza Rosca J.C.,
Herrera Santana E.D.,
Rodriguez Castro J.,
Santana Lopez A.,
Vasilescu E.V.,
Drob P.,
Vasilescu C.
Publication year - 2005
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.200503885
Subject(s) - passivation , materials science , titanium , dielectric spectroscopy , open circuit voltage , oxide , titanium oxide , titanium alloy , dissolution , nyquist plot , alloy , anode , electrochemistry , chemical engineering , analytical chemistry (journal) , metallurgy , inorganic chemistry , composite material , electrode , chemistry , layer (electronics) , electrical engineering , voltage , chromatography , engineering
The properties of the anodic oxide films formed on titanium and its implant alloys Ti‐5Al‐4V and Ti‐6Al‐4Fe are investigated in this paper. Anodic oxide films were prepared by electrochemical treatment in 3M sulphuric acid solution at 60 V for 1 min, followed by a thermal treatment consisting of heating at 500°C for 24 h and then cooling in water. Electrochemical impedance spectroscopy (EIS) measurements were carried out at open circuit potential. Nyquist and Bode spectra exhibit a two‐time constant system, attesting an oxide with two layers: a barrier inner oxide and a porous outer one. All spectra change in time, indicating a thickening of the films. Open circuit potentials were monitored (long‐term, 25,000 exposure hours) in Ringer 2 solution of different pH values (6.98, 4.35, 2.5) for titanium, Ti5Al‐4V and Ti‐6Al‐4Fe alloy but without treatment with the purpose to compare the biomaterial behaviour. It was pointed out some variations of the open circuit potentials around electropositive values, suggesting slow dissolution, re‐passivation or adsorption processes.