Corrosion testing of platinum metals CVD coated titanium anodes in seawater-simulated solutions

A chemical vapour deposition (CVD) technique is widely used for the preparation of protection coatings. In the present work titanium anodes with CVD coatings of iridium, platinum and Ir–Pt composite were made. The coatings were obtained by thermolysis of platinum(II) acetylacetonate and iridium(III) acetylacetonate in the oxygen or hydrogen contained atmosphere. The investigation of the samples by means of XPS showed the presence of oxide phases in the coatings. Tests of the resulting samples in the electrolysis of seawater-simulated solutions under active evolution of oxygen were conducted. Platinum coatings were found to be more stable than iridium ones, which is, to a substantial extent, due to mechanical strain at the titanium-to-coating boundary. Iridium-coated titanium foil anodes were tested in an experimental electrodialysis unit. Their service life exceeded 1 year.

Protective coatings for titanium anodes are prepared by CVD of iridium, platinum and Ir–Pt composite within a wide range of deposi-tion characteristics. The tests of the resulting samples in the electrolysis of seawater-simulated solutions demonstrated that the stability of the coating is determined by its composition and preparation conditions; platinum coatings were found to be more stable than iridium ones, which is, to a substantial extent, due to mechanical strain at the titanium-to-coating boundary. Tests in a hard regime under active evolution of oxygen allowed us to estimate comparative stability of the samples within relatively short periods of time.