Investigation of the electrochemical behaviour of TiMo alloys in simulated physiological solutions

Abstract

This paper addresses on the electrochemical behaviour of three TiMo alloys exposed to simulated physiological environments. Their stability and corrosion resistance was characterized in order to explore the potential application for the manufacturing of implant materials. Ringer's solution together with an acidic modification of the Ringer's solution (pH = 3.1) at room temperature were considered. Both electrochemical methods (namely, potentiodynamic polarization curves and electrochemical impedance spectroscopy, EIS), and spatially-resolved scanning electrochemical microscopy (SECM), were used. Additionally, surface characterization was made employing optical microscopy and scanning electron microscopy (SEM). The oxide films formed on the TiMo alloys in neutral and acidic Ringer's solutions effectively protect the metal from dissolution in this environment, and no breakdown of the passive layer occurs in the potential range up to +1.00 V vs. SCE. SEM micrographs of retrieved samples do not show corrosion pits, cracks, or any other defects despite the rather high positive potential values reached during the potential excursion. EIS data reveal that two-layer oxide films are formed, consisting of a porous outer layer and a compact inner layer (approximately 5-6 nm thick), the latter accounting almost completely for the corrosion resistance of the materials. The corrosion resistance of the inner compact film towards metal dissolution is smaller in the acidic environment, whereas it increases with higher Mo contents in the alloy. The passive oxide films exhibit dielectric characteristics towards charge transfer, and they are imaged as insulators by scanning electrochemical microscopy.

Investigation of processing effects on the corrosion resistance of Ti20Mo alloy in saline solutions

“…Moreover, alloying titanium with Mo β-stabilizers improves the corrosion resistance [4][5][6][7][8][9][10], in addition to adequate mechanical compatibility and good cytocompatibility [11][12][13][14][15][16] despite one controversial report [17]. Unfortunately, titanium and molybdenum are difficult to alloy through a conventional melting-casting process due to the big difference in melting point and specific gravity between the two metals.…”

Microstructural, electrochemical and tribo-electrochemical characterisation of titanium-copper biomedical alloys

“…The maps obtained by SECM provide information of the chemical activity of the oxide layer/electrolyte solution interface. Bolat et al [22] studied the electrochemical behaviour of three Ti-Mo alloys exposed to simulated physiological environments by SECM and observed that the oxide films formed on the surface of the alloys exhibit dielectric characteristics towards charge transfer.…”

Properties of aluminum oxide thin film obtained by metal plasma immersion ion implantation and deposition after zirconium-based pretreatment

“…The presence of organic topcoat shifted to OCP to nobler values at the end of the monitoring period. It is well-known from the literature that more cathodic values of the OCP indicate an electrode surface more stable and less susceptible to corrosion reactions [26]. In this respect, the presence of the organic layer improved the thermodynamic stability of the system.…”