| Popis: |
The fabrication and some properties of three cermets have been investigated in outline. Fabrication by hot-pressing methods is feasible, provided an argon atmosphere is used. The thermal-shock properties of UO 2 are not improved by the addition of zirconium; however, the UO 2 Th system, at high metal contents, and to a lesser extent the UO 2 Si system, up to 60 v/o of metal, show improvement in this respect. The poor properties of the zirconium cermets is probably due to oxygen embrittlement of the zirconium as a result of reaction with the oxide constituent. The use of silicon as the metallic constituent at 20 per cent by volume improves the oxidation resistance of UO 2 in air at temperatures up to 900°C. Addition of silicon beyond 20 v/o has little effect on the. rate of oxidation. |
