Tungsten cermet fabrication by a joule heating process

Fabrication of tungsten cermet pellets dispersed with zirconia (ZrO ₂) fuel particles, used as a surrogate for UO₂, was achieved using a direct resistance fabrication technique, referred to as Joule heating. The pellets consisted of 200μm ZrO₂ particle dispersed within 6pm tungsten particles. The experimental setup consisted of a ZrO ₂ die which contained a W-ZrO₂ powdered sample. Graphite leads were brought into contact with the sample allowing for the flow of current. The die was encased in a glass cylinder and filled with argon to prevent oxidation of the tungsten and degradation of the graphite leads as the temperature was increased. Acceleration of densification was carried out by springs, yielding about 750KPa, which were attached to the graphite contacts enabling a constant load to be applied to the sample during heating. This experiment varied the volume percents of ZrO₂, (40%, 50%, and 60%), in the sample pellets. Zirconia loading, applied load, current, voltage, and power level were varied as input parameters. Effects of these input parameters on product density, porosity, ZrO₂ dissociation, and introduction of multiple phases was investigated.