LITHIUM METAZIRCONATE FOR NUCLEAR APPLICATION - PHYSICAL AND MECHANICAL-PROPERTIES

Lithium metazirconate is a candidate in fusion reactor designs as a tr itium-breeding material. An amorphous powder was synthesized by gellin g zirconium propylate and lithium acetate: after heat treatment at 900 degrees C, pure Li2ZrO3-I was obtained. Preliminary tests made on sin tered pellets, obtained from this powder, demonstrated an appropriate tritium release at low temperature, when the sample porosity was about 20% and the mean pore radius 3 mu m. The subject of this paper was to realize a good compromise between mechanical properties and the sprea d porosity, necessary for tritium diffusion. Dilatometric investigatio ns were performed on compacts of powders treated at 800, 900 and 1000 degrees C to identify the best temperature and time of sintering. The calcined powders were also uniaxially pressed at 200, 300 and 500 MPa: the green bodies were sintered at 1200, 1250 and 1300 degrees C for 2 or 4 h, in order to produce ceramics having different porosity. On th e sintered bodies, the pore size distribution, the mean pore radius an d mechanical properties were evaluated.