The reactions between TiC or TiN powder and H2O have been studied at 200°-650°C under 100 MPa. The reaction of TiC with H2O above 400°C for 3 h yielded anatase, CH4, CO2 and H2, and above 500°C rutile was formed additionally. TiN power with an average grain size of 1.4 μm reacted with H2O above 290°C to yield anatase, NH3 and H2, while TiN powder of 9 μm reacted H2O above 480°C and yielded rutile, NH3 and H2. The oxidation rate calculated from the weight gain was compared with model kinetic equations. In TiC the rate was best described by the Avrami-Erofeev equation (n=1.3), while the core-shrinking model fitted as well. This suggests that the reaction was controlled by the phase boundary reactions. In TiN the Jander-type model was best, which suggests that the reaction was controlled by diffusion through the oxide scale. An Arrhenius plot of the rate constants gave an apparent activation energy of 98 kJ/mol. The difference between reaction mechanisms is attributed to the difference in the gaseous species of reaction products.
|Number of pages||9|
|Journal||Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan|
|Publication status||Published - 1989 Dec 1|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry