Effect of fluoride ions on Ti6Al4V alloy passivation in lactated Ringer's serum

Abstract

The corrosive behavior of Ti and its alloys in fluoride media is well known. Based on electrochemical studies, this paper describes the effect of fluoride ions on the passive behavior of Ti6Al4V alloy in lactated Ringer's serum. The open circuit potential of the alloy in the serum, which lies in the passive region of TiO 2 , shifts to more negative values as fluoride ions are added. The voltammogram obtained in the serum presents an active-passive behavior close to -0.2 V (SCE) that changes with the presence of fluoride ions, evidencing higher anodic currents. Electrochemical impedance spectroscopy plots obtained at OCP after varying immersion times in the serum display an almost capacitive behavior and the polarization resistance becomes enhanced after 7 days. With the addition of fluoride ions, the film's resistance decreases, but a stable protective layer develops after 7 days of immersion time, indicating the film's repair.

Corrosion behavior of Ti and TI6Al4V in citrate buffers containing fluoride ions

“…The sepctrum shows a near capacitive behavior typical of passive materials and this does not change on increasing the exposure time but the film resistance decreases after 7 days immersion. These findings are different from those observed in Ringer serum containing equal fluoride concentration, in which the oxide film stability was enhanced after 7 days' immersion in this medium 16 . This difference may possibly be related to the presence of citric acid in the buffer producing a more defective film.…”

“…These facts are in good agreement with was reported in the literature for Ti based materials [17][18][19][20][21][22] . The equivalent circuit (EC) used to describe the experimental data was based on a two-layer model consisting of a barrier inner layer and a porous outer layer [16][17][18][19][20][21] . The proposed EC is R s (Q 1 [R 1 (R 2 Q 2 )]) given in Figure 7b.…”

Simultaneous degradation by corrosion and wear of titanium in artificial saliva containing fluorides

“…The good corrosion resistance of titanium in different environments allows its use in several engineering and medical applications [1][2][3][4][5][6][7]. For medical applications, the stable oxide surface film on titanium is biologically acceptable, but once must be aware that the stability of the oxide film depends on the corrosivity of the environment in contact with the titanium [8][9][10].In-vitro tests in artificial saliva are used to simulate the degradation of prostheses and implants exposed to an oral environment [1][2][3][4][5][6][7]11].…”

“…For medical applications, the stable oxide surface film on titanium is biologically acceptable, but once must be aware that the stability of the oxide film depends on the corrosivity of the environment in contact with the titanium [8][9][10].In-vitro tests in artificial saliva are used to simulate the degradation of prostheses and implants exposed to an oral environment [1][2][3][4][5][6][7]11]. Passive films on titanium behave like a compact oxide film in artificial saliva at pH 3.0-3.8 [8,9].…”

Spectroscopic Characterization of Titanium Alloy Surface in a Biological Medium

“…The effect of fluoride ions on the passive behavior of Ti6Al4V alloy in Ringer's solution was studied by Schmidt et al [16]. The open circuit potential (OCP) shifts to more negative values when fluoride ions are added.…”