Abstract
Hydrothermal hot-pressing method has been used to prepare compacts at relatively low temperatures by compression of powders under hydrothermal conditions. The compression accelerates the densification of the powders and hydrothermal treatment gives bonding of particles, so that compacts with high mechanical strength can be produced. When glass powders were densified by hydrothermal hot-pressing, water in interstices of the glass particles diffused into glass structure and fully densified compacts were obtained. On the other hand, when water in interstices of the particles remained even after hydrothermal hot-pressing, porous materials were formed. Pore volume and pore diameter distribution of the porous materials could be controlled by selecting hydrothermal hot-pressing conditions. This technique has been employed for immobilization of radioactive wastes.
