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The wet corrosion by high temperature-high pressure water has been studied on the three types of Si-Ti-C-O system (Tyrano) fibers at 300∼800°C under 100 MPa for 2h. The X-ray diffraction analysis and SEM observation of the scale layers and the measurement of the mass change of reaction products revealed that the pyrolysis together with forming β-SiC crystal took place in lower temperatures, while the hydro-thermal oxidation with following the formation of amorphous silica films propagated in higher temperatures. The oxidation reaction was sharply reduced as the amor-phous silica crystallizes to form cristobalite, whence the porous oxide layer is densified. The densification hindered the gaseous diffusion through the oxide film. The fiber containing 18% O (rich type), where atomic arrangement was disordered, showed a comparatively rapid pyrolytic rate. On the contrary, the fiber containing 12% O (poor type) showed a rapid oxidation rate.

NOxの解媒を用いた除去法について簡単にふれ, オゾン層破壊やグリーンハウス効果を引き起こし, 自動車の排ガス処理用三元触媒コンバーター(TWC)内で発生するN2Oについて記した。N2OはNOの不均化反応(4NO→N2O+N2O3)によって生じることを指摘し, 種々のY型ゼオライトやアルカリ土類酸化物の触媒活性サイトの特性について説明した。さらに, NOの還元反応や吸収について不均化反応の観点から再検討した。

Room temperature stability of metastable tetragonal-zirconia microcrystals in their composite ceramics has been argued from the standpoint of the constraint force (σ) of matrix, which was calculated by Eshelby's equation. The equation is based on the assumption that the dispersed particles and matrix are independent each other and then the effect of the interface can be ignored. However it was found that there was no significant relations between the critical size (dc) (an index of stability) of the microcrystals and the constraint force. This means that the interaction (the effect of the interface) between the dispersed particles and the matrix cannot be ignored in these materials. The t→m phase transformation of ZrO2 was influenced by not only “matrix effect” and “surface energy one” but also “interface one”. It was insisted that a kinetical discussion was also important in analysing the transformation mechanism. It seems to be probable that the field strength (Z/a2) of the metal ions existing in the interfacial layer effects on the dc value.