Effect of Potential and Microstructure on the Tribocorrosion Behaviour of Beta and Near Beta Ti Alloys I

Abstract

Current hip prostheses make extensive use of the aerospace alloy Ti-6Al-4V. This material was designed for aerospace applications but has far from ideal mechanical properties for biomedical applications, namely, a high elastic modulus and poor fatigue resistance. Moreover, its poor tribological properties are well known.However, beta, or near beta Ti alloys are known to have superior properties in that its elastic modulus is closer to that of bone coupled with a good fatigue resistance.Therefore, this work aims to analyse the tribocorrosion behaviour of 4 different titanium alloys (Ti-13Nb-13Zr, Ti-12Mo-6Zr-2Fe and Ti-29Nb-13Ta-4.6Zr aged at 300 o C and at 400 o C) at anodic potential, OCP and cathodic potential at 0.5N, 1N and 2N in bovine serum to identify the main cause of material degradation, the presence of a tribofilm and the synergism between corrosion and wear. The results show the alloys become more active when subjected to sliding in all conditions, but the material loss is lower at anodic potential. The alloys studied present a positive effect of corrosion on wear.

Effect of Potential and Microstructure on the Tribocorrosion Behaviour of Beta and Near Beta Ti Alloys II

“…This study aimed to identify the main acting wear mechanism, including tribofilm characterization as well as subsurface microstructural changes, of the four distinct titanium alloys (Ti13Nb13Zr, Ti12Mo6Zr2Fe, Ti29Nb13Ta4.6Zr aged at 300 °C and at 400 °C) tested under various tribocorrosion conditions. We identified in our previously published Part I of this study [21] a synergism between wear and corrosion, where material loss was highly affected by mechanical wear and, to a lesser degree, corrosion. Overall, the material loss, wear track volume and wear rates showed lower values at anodic conditions.…”

“…The previously published part I of this study demonstrated that the tested titanium alloys had low wear track volume and material loss at anodic conditions [21]. Therefore, we opted to investigate the wear track subsurfaces of the titanium alloys at this condition to characterize their microstructural features and to detect any presence of a Fig.…”

“…The 4 titanium alloys were classified according to their microstructure: αβ alloy (Ti13Nb13Zr), Nβ alloy (Ti12Mo6Zr2Fe), β alloy (Ti29Nb13Ta4.6Zr aged at 400 °C) and βω alloy (Ti29Nb13Ta4.6Zr aged at 300 °C). These abbreviations were adopted from the previously published Part I of this study [21] and Table 1 shows the alloys' composition.…”

“…The tested surfaces were analysed by a Focused Ion Beam (FIB FEI Quanta 200 3D, Netherlands) and a Transmission Electron Microscope (TEM JEOL JEM-F200) at 120 kV accelerating voltage with a housed Energy Dispersive X-ray spectrometer (EDS, Oxford Instruments). A complete description of the sample preparation, tribocorrosion tests and surface characterization are detailed in our previous work [21,25].…”

“…Previously, the published Part I of this study explored 4 distinct titanium alloys (Ti13Nb13Zr, Ti12Mo6Zr2Fe, Ti29Nb13Ta4.6Zr aged at 300 °C and at 400 °C), where outputs including wear rates, electrochemical behaviour and the tribocorrosion synergism estimations were assessed [21]. The results showed that the microstructure influences the tribocorrosion properties of titanium alloys, where lower wear track volume, material loss and friction were observed on the alloys with α phase, especially at anodic condition.…”