CORROSION STABILITY OF TIN PREPARED BY ION-IMPLANTATION AND PVD

Thermodynamic U/pH diagrams for TiN were calculated which predict only a small range of stability in alkaline solutions. In contrast, electrochemical experiments in solutions of different pH values show high stability against oxidation and reduction. The properties of TiN layers were investigated by potentiodynamic, potentiostatic and open circuit experiments. The observations were compared to results from XPS. Corrosion measurements with nitrogen implanted Ti revealed corrosion resistance even in hot concentrated acids. This feature could not be found for TiN prepared by physical vapour deposition. The higher corrosion rates of PVD samples in contrast to layers formed by ion implantation refer to their columnar structure. Subsequent ion implantation of TiN-PVD decreases the current densities by a factor of 10.