Abstract
The structures of passivation films of sintered Ti-(0, 10, 20, 30, 40, 100)mass%Mo alloys formed in 35%HCl, 3%NaCl and 103mol/m3(3.8%)NaOH solution were studied by X-ray photoelectron spectroscopy (XPS). X-ray photoelectron spectra of Mo3d, Ti2p and Ols of Ti-Mo alloys immersed in a 35%HCI solution showed that Mo4+/Mo6+ ratio of the passivation film increased with increasing Mo content in the alloy and that Mo in the passivation film was enriched by the preferential dissolution of Ti. This showed that Mo4+ in this film was important for improving its corrosion resistance. From X-ray photoelectron spectra of Ti-Mo alloys immersed in a 3%NaCI solution, it was indicated that the Mo content in the passivation film was equal to that in the alloy and that the passivation film were composed of Mo6+ and Ti4+. On the other hand, X-ray photoelectron spectra of Ti-Mo alloys immersed in a 3.8%NaOH solution showed that Ti in the passivation film was enriched by the active preferential dissolution of Mo. It was thought that the passivation film composed of a stable Ti oxide improved the corrosion resistance in NaOH solution.
