In the field of biomedical applications a special interest exists regarding the study of the physicochemical and mechanical behaviour of materials, with special focus on the electrochemical degradation of metal/ceramic interfaces. In fact, metal/ceramic interfaces may be present in several biomedical devices, ranging from external or implantable sensors, to dental implants. Diffusion bonding represents an important technique since, in opposition to other production technologies, such as active metal brazing, avoid the possible liberation of certain chemical components harmful to health. The aim of this work is to study the electrochemical degradation of the interface formed between commercially pure Ti and Al2O3 produced by diffusion bonding, in contact with a physiological solution. The present approach included the evaluation of the contribution of individual and pairs of interfacial layers on the global degradation processes. For this propose d.c. electrochemical techniques were used to monitor the open-circuit potential, and to perform potentiodynamic polarization and galvanic corrosion evaluation. Also, electrochemical impedance spectroscopy was used as a complementary technique of the corrosion behaviour of the interface. Chemical composition and morphology of samples and corrosion products were evaluated by SEM and EDS analysis. According to experimental results, two principal reaction layers were formed in the interface: TiAl and Ti3Al. The TiAl layer appears to be the responsible for the strong increase in corrosion rate of the interface.
degradation; interfaces; metal/ceramic joining; galvanic corrosion; EIS
