Galvanic coupling of Ti with Cu and Al alloys in chloride media

In this work, a new ternary Ti–25Ta–5Zr alloy (with nontoxic alloying elements) was obtained and used to develop a thermo‐mechanical procedure in order to optimize the balance strength – elastic modulus. Data about structural (by SEM) and mechanical properties are investigated. Also, its electrochemical behaviour in Ringer–Brown and Ringer solutions of different pH values (simulating severe functional conditions of an implant) was studied by cyclic potentiodynamic and linear polarization and electrochemical impedance spectroscopy (EIS). From cyclic potentiodynamic polarization curves it resulted the nobler behaviour of the thermo‐mechanical treated alloy than as‐cast alloy due to the favourable influence of the applied processing. Impedance spectra were fitted with one time constant equivalent circuit characterizing a very stable, resistant oxide passive film. The values of the open circuit potentials for the treated alloy are nobler than of the as‐cast alloy and tended to more positive values in time, proving that the passive film on its surface is more compact and thickened in time.

Section: Resultsmentioning

confidence: 99%

Improvement of the corrosion resistance and structural and mechanical properties of a titanium base alloy by thermo‐mechanical processing

Cojocaru

Răducanu

Cincă

et al. 2012

“…From Table 4 it can be observed that the open circuit potential gradients varied from 0.004 to 0.170 V; these low values cannot generate galvanic cells or local corrosion because only differences of 0.6 Ä 0.7 V can initiate and maintain galvanic cells [39,40]. It results that, for 5000 exposure hours, it is not possible to appear galvanic or local corrosion on the Au-20Pd-10Ag-5Ti alloy surface, in conditions of large variations of pH values and saliva compositions.…”

Section: Monitoring Of Open Circuit Potential Gradientsmentioning

confidence: 99%

Corrosion behaviour and biocompatibility of a new dental noble AuPdAgTi alloy

Răducanu

Cîmpean

Vasilescu

et al. 2010

The aims of the study were to investigate the electrochemical response of a new dental Au-20Pd-10Ag-5Ti alloy in artificial Carter-Brugirard saliva and to assess its biocompatibility using gingival fibroblast culture. Electrochemical techniques of potentiodynamic and linear polarization were used. Also, the open circuit potentials and the corresponding open circuit potential gradients were monitored for 5000 exposure hours. The gingival fibroblast response to Au20Pd-10Ag-5Ti alloy was estimated by LDH-cytotoxicity, MTT cell proliferation assays, the assessment of substrate-dependent changes in extracellular fibronectin network, cell morphology and actin cytoskeleton organization. The cyclic potentiodynamic curves of Au-20Pd-10Ag-5Ti alloy exhibited a passive behaviour with transpassive dissolution of silver, without pitting corrosion. Open circuit potentials were finally stable at noble values. Open circuit potential gradients have low values that could not generate galvanic or local corrosion. The new Au-20Pd-10Ag-5Ti alloy did not promote cell damage and alterations in cell adhesion and morphological features, exhibiting a good biocompatibility.

“…Because of this reason, the potential gradients created by a zone of implant in contact with Carter-Brugirard saliva and another zone of the implant Table 5. It shows that the highest potential gradient (in absolute value) for Ti is 0.069 V and for Ti-6Al-7Nb is 0.103 V. These values are not dangerous for the implant integrity because only values greater than 0.6 V [41] can produce galvanic cells [42][43][44] and can accelerate the corrosion or can initiate local corrosion. Figure 4 shows the morphology of osteoblasts after cell culture for 6 d. Fig.…”

Section: Open Circuit Potential Gradientsmentioning

confidence: 99%

The relation between electrochemical tests and in vitro evaluation of titanium alloy biocompatibility

Popa¹,

Demetrescu

Iordǎchescu

et al. 2007

In this paper, the electrochemical behaviour of the titanium and Ti-6Al-7Nb alloy in artificial saliva (Tani&Zucchi and CarterBrugirard), ion release tests and in vitro biocompatibility of human osteoblasts (HOB) were studied. Titanium and its implant Ti-6Al-7Nb alloy present self-passivation and very stable passive films in Tani&Zucchi artificial saliva of pH ¼ 2.5; 5; 6.7; 9; the total quantity of ions released in the artificial saliva and corrosion rates are very low, proving a very good corrosion resistance and very low toxicity. In undoped and doped Carter-Brugirard saliva, the open circuit potentials have highly electropositive values, denoting passive state and good stability; the open circuit potential gradients, simulating the non-uniformity of the saliva composition, show very low values, no danger for the implant integrity. The in vitro cytotoxicity of Ti-6Al-7Nb alloy was evaluated on the basis of cell morphology and cell viability. The results obtained revealed a high biocompatibility between HOB and Ti-6Al-7Nb alloy.