ABSTRACT
The influence of the microstructural parameters on the corrosion stability of Y–TZP (Yttria–Stabilized Tetragonal Zirconia Polycrstals) has been clarified and can be understood on the basis of martensitic transformations. Nevertheless, the role of water for the degradation mechanism is still unclear. One possible explanation for the enhancement of the degradation in the presence of water is to assume that water radicals (such as hydroxile groups or similar configurations) penetrate into the lattice. In order to test this hypothesis 3Y–TZP (known to be very sensitive to degradation) and 15Ti–3Y–TZP (very corrosion resistant) samples were aged in an autoclave in a D2O rich water atmosphere. The presence of hydrogen and deuterium in the lattice was then monitored by ERDA (Elastic Recoil Detection Analysis), by applying a beam of 1.9 MeV 4He ions under an incident angle of 20°. While sintered and polished, but otherwise untreated 3Y–TZP samples show hydrogen mainly at the very surface with only a very small bulk concentration, they exhibit a significantly increased hydrogen concentration after the aging treatment: concentrations of 9•1020 atoms/cm3 for H and 5 • 1020 atoms/cm3 for D were recorded. Within the experimental accuracy the total H and D concentration is of the same order of magnitude as the concentration of stoichiometric vacant oxygen sites. The concentration of hydrogen in the more corrosion resistant Ti–containing material, however, was found to be only slightly higher than in an untreated sample.
