The purpose of this work was to evaluate the corrosion of commercially pure (CP) titanium and Ti6Al4V in vitro at different F(-) concentrations regularly found in the oral cavity by using different electrochemical tests and surface analysis techniques. electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) and potentiodynamic polarization tests were associated to advanced characterization techniques such as SEM, EDS, AFM, ICP-MS and XPS. OCP tests revealed a higher reactivity of both CP titanium and Ti6Al4V at 12,300 ppm F(-) concentration than that recorded at 227 ppm F(-). Also, a significant decrease of the corrosion resistance of both materials was noticed by EIS in fluoride solutions. Material loss caused by corrosion was noticed on titanium surfaces by SEM and AFM in the presence of high F(-) concentration. CP titanium degraded by pitting corrosion while Ti6Al4V suffered from general corrosion showing micro-cracks on surface. Furthermore, a high release of metallic ions from the test samples after immersion at high F(-) concentrations was detected by ICP-MS, that can be potentially toxic to oral tissues.

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Recently, tribocorrosion is widely accepted as an interdisciplinary area of research and such studies on various materials is gaining more attention by scientists and engineers due to its practical and economical significances in a wide range of applications. Hence the main objective of present work was to investigate the tribocorrosion behavior of single layered titanium oxycarbide, TiCxOy, thin films on a reciprocating sliding tribometer, and in the presence of artificial sweat solution at room temperature. Such films can be used as decorative coating on various components. The films were produced by dc reactive magnetron sputtering, using C pellets incrusted in the Ti target erosion area. A gas atmosphere composed of Ar and O2 was used. The Ar flow was kept constant, and the

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Porous Ti implants are being developed in order to reduce the biomechanical mismatch between the implant and the bone, as well as increasing the osseointegration by improving the bone in-growth. Most of the focus in the literature has been on the structural, biological and mechanical characterization of porous Ti whereas there is limited information on the electrochemical characterization. Therefore, the present work aims to study the corrosion behaviour of porous Ti having 30 and 50 % of nominal porosity, produced by powder metallurgy route using the space holder technique. The percentage, size and distribution of the pores were determined by image analysis. Electrochemical tests consisting of potentiodynamic polarization and electrochemical impedance spectroscopy were performed in 9 g/L NaCl solution at body temperature. Electrochemical studies revealed that samples presented a less stable oxide film at increased porosity, more specifically, the complex geometry and the interconnectivity of the pores resulted in formation of less protective oxide film in the pores.

This paper reports the influence of low pressure plasma nitriding treatments, some of them followed by plasma assisted oxidation on the mechanical properties and tribocorrosion resistance of a Ti6Al4V alloy. Nitridation was performed for 640 or 720 min at 600 and 700°C in a r.f. plasma equipment, using a N 2-H 2 gas mixture at 7.5 Pa. Some of the samples were then post-oxidized at 700°C for 15 and 60 min, within a O 2 plasma of 9.5 Pa. XRD results revealed the occurrence of the Ti 2 N phase for the nitrided samples. The oxidized surface layers are poorly crystallised with rutile and traces of anatase TiO 2 nanocrystallites. Microhardness tests showed a significant improvement of the surface hardness whatever the treatment, with a slight effect of the treatment temperature. The tribocorrosion results clearly showed that plasma treatments have a strong influence on the tribocorrosion behaviour of the material. Both the corrosion and wear performance of the samples are improved by the increase of the processing temperature.

The aim of this work is the investigation of the tribocorrosion behaviour of single layered zirconium oxynitride, ZrO x N y , thin films in reciprocating sliding and immersed in an artificial sweat solution at room temperature. During the wear tests samples were kept under potentiostatic control and the corrosion current were monitored. Also, Electrochemical Impedance Spectroscopy (EIS) tests were performed before and after sliding in order to evaluate, in detail, the modification of the protective character of the coating caused by the joint action of wear and corrosion. The modifications of the coating structure and microstructure and/or chemical composition originated by the variation of the deposition parameters were also evaluated and correlated with the corrosion mechanisms occurring in each system.

The main aim of this work is the investigation of the corrosion resistance of single layered zirconium oxynitride, ZrN x O y , thin films in artificial sweat solution at ambient temperature. The films were produced by rf reactive magnetron sputtering, using a pure Zr target at a constant temperature of 300 8C. Two different sets of samples were produced. In the first set of films, the substrate bias voltage was the main variable, whereas in the second set, the flow rate of reactive gases (oxygen/nitrogen ratio) was varied. The control of the amount of oxygen allowed the film properties to be tailored from those of covalent zirconium nitride to those of the correspondent ionic oxide. The corrosion behaviour was evaluated by potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) tests. The analysis of EIS data provided detailed information of the corrosion processes occurring at the surface of the system throughout the immersion time. The modifications of the coating microstructure and/or chemical composition induced by the variation of the deposition parameters were also evaluated and correlated with the corrosion mechanisms occurring in each system.