有機金属化学蒸着法により形成したクロム酸化物皮膜の亜臨界水及び超臨界水中での化学的安定性

抄録

The stability of chromium oxide film in subcritical and supercritical water was studied to clarify the corrosion behavior. Platinum specimen was coated with chromium oxide by metal organic chemical vapor deposition. Time variation of the weight change of the chromium oxide film during immersion in high temperature water was obtained, and the structure of the film was examined by scanning electron microscope, X-ray diffraction, and Raman spectroscopy. It was found that the chromium oxide film on the platinum specimen disappeared after the immersion in the DO (dissolved oxygen)=8000 ppb pure water at 623 K, while the weight and the structure for the specimen were almost unchanged during immersion in deaerated pure water. The loss rate of the chromium oxide film during the immersion in the pure water in the presence of dissolved oxygen at 623 K was much larger than that at 723 K. The crystallinity of the film after immersion in the pure water at 723 K was higher than that before the immersion from X-ray diffraction patterns and Raman spectra. The mechanism of the loss of chromium oxide films was discussed in terms of the dissolved oxygen in subcritical and supercritical water.