Torsional fretting corrosion behaviours of Ti6Al4V alloys in Hank’s simulated body fluid

Abstract

Torsional fretting corrosion in a physiological medium is one of the main reasons that artificial joints fail. In this study, we carried out experiments on torsional fretting corrosion in Titanium alloys (Ti6Al4V) against Zirconium dioxide (ZrO 2 ) ceramic balls under 37°C in a Hank's simulated body fluid. During the tests, we recorded electrochemical corrosion parameters using an electrochemical analysis system in real-time. We analysed the torsional fretting dynamics behaviours, damage mechanisms, and electrochemical corrosion behaviours in detail using the micro-examinations of a scanning electron microscope (SEM), an energy-dispersive X-ray (EDX), a profilometer, and an X-ray photoelectron spectrometer (XPS). The results showed that the dynamics behaviours strongly depended upon the torsional angular displacement amplitude and the number of cycles. The friction torque increased with increases in the torsional angular displacement amplitude and normal load. We established a running condition fretting map (RCFM), which included three fretting running regimes: a partial slip regime (PSR), a mixed fretting regime (MFR), and a slip regime (SR). We determined that the influences of torsional fretting on electrochemical corrosion behaviours were strongly correlated to the angular displacement amplitude. Under large angular displacement amplitudes, the corrosion of the Ti6Al4V alloys in Hank's simulated body fluids were accelerated by torsional fretting, especially during the initial stage of the test. However, when the angular displacement amplitude was smaller than 1°, the corrosion potentials and corrosion currents were almost invariable during the entire duration of the test. The damage to the Ti6Al4V alloy was the result of wear and corrosion. The wear mechanisms were attributable to delamination and abrasive wear in the three fretting regimes. We observed almost no damage on the contact centre and only slight scratches and wear on the contact edge in the PSR. In MFR testing, the damage zone extended to the contact centre and the sticking zone (which exhibited no damage) contracted to the contact centre with increases in the number of cycles. Ultimately, in MFR and SR testing, the damage mechanisms were primarily the result of abrasive wear, oxidation wear, tribochemical reactions, adhesion wear, and electrochemical corrosion.

Corrosion Resistance of a Plasma-Oxidized Ti6Al4V Alloy for Dental Applications

“…This is expected, as the polarization tests were started at a cathodic potential relative to the corrosion potential, so that the passive film at the surface was at least partially removed due to the highly reducing initial potentials. For untreated alloy, data exhibited the presence of only one passive zone, which extends over the whole tested potential interval without evidence of a pitting potential value, E pit , similar to that reported in the literature [18][19][20][21]32,45,46] interval where the passive current density, I pas , remained more or less constant. Alloy Ti6Al4V can generate passive films containing Ti 2 O 3 , TiO (anatase), and TiO 2 (rutile).…”

“…Based on the phase angle data, it can be seen that the maximum phase angle is for samples oxidized during 2 h and 3 h, which decreases for shorter or longer oxidation time. A phase angle close to −80 • that is extended over a wide interval of frequency values is characteristic of a metal covered with a very stable passive layer, typical of Ti alloys [17][18][19][20][21][45][46][47]. For specimens oxidized during 2 h and 3 h, two peaks can be clearly seen, corresponding to the double electrochemical layer and to the oxides film, respectively.…”

“…Among Ti alloys, one of the most remarkable alloys is Ti6Al4V, which is especially useful as an implant material, including dental implants, in the health sector [9][10][11][12][13][14]. The corrosion and oxidation resistance of this alloy is based on the development on their surface of a mixture of TiO 2 and Al 2 O 3 oxides [15][16][17], which provide a very stable passive layer and protect the alloy against the corrosive action of substances in the environment, such as chlorides, sulphates, and acids, among others [18][19][20][21]. However, that corrosion resistance is lowered when aggressive ions such as chloride are present, which makes these alloys highly susceptible to a localized type of corrosion such as pitting.…”

Corrosion behavior of fiber laser welded Ti-6Al-4V alloy rods with different pH and temperature in 0.9 wt% NaCl medium

“…The high preference for Ti-6Al-4V alloy as a biomaterial is due to high corrosion and abrasion resistance, low density, biocompatibility, high tensile strength and hardness properties. Its high corrosion resistance and biocompatibility are thanks to the thin oxide (TiO2) layer formed on the outer surface of the metal due to titanium contact with oxygen [7][8][9][10][11][12][13]. These TiO2, and TiO3 layers formed on the surface may lose their properties by being affected by some environmental factors.…”

An Experimental Study on the Fretting Corrosion Behaviours of Three Material Pairs at Modular Interfaces for Hip Joint Implants

“…Liu et al [34] found that the presence of inflammatory factors in the body reduced the stability of the oxide film on the surface of the alloy. In addition, torsional fretting corrosion behaviours of materials for artificial joints were also studied by Wang [35,36] and Lin [37,38].…”