Bunkei Ky\=o1, Kumao Uchida1 and Sh\=osuke Imoto2
1Department of Nuclear Engineering, Faculty of Science and Engineering, Kinki University, Higashiosaka
The hydrolytic behavior of Hafnium mononitride and monocarbide has been studied and compared with that of Titanium and Zirconium nitrides and carbides.
In the case of hydrolysis of HfN the gaseous products were H2, N2 and a small amount of NO, and the liquid product was NH3, as in the case of TiN and ZrN. In isothermal hydrolysis the principal product was NH3 at temperatures lower than 800°C, which was replaced by N2 at temperatures higher than 900°C. In this respect HfN was similar to ZrN, but not to TiN which produced mainly N2 even by hydrolysis at 800°C.
The products of hydrolysis of HfC were found to be CO, CO2, H2 and a small amount of CH4 also as in the case of TiC and ZrC. In the isothermal hydrolysis of HfC it was observed that a large amount of H2 evolved at the early stage of the hydrolysis while CO2 continued to evolve with some amount of H2 even after the ceasing of CO evolution. From analysis of the hydrolytic behavior the solid residue after the hydrolysis of HfC was considered to contain some waxes (CnHm).
It was suggested that the carbide of the element of smaller atomic number (Ti) would tend to form oxygen compounds (CO, CO2) while the carbide of the element of larger atomic number (Zr, Hf) hydrogen compounds (CnHm), since ThC and UC formed only hydrocarbons and H2 by hydrolysis. This suggestion was also valid to nitride.
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