Sintering behavior and DC emission properties of tungsten-rhenium mixed matrix dispenser cathodes

Tungsten-rhenium mixed powders were prepared by a spray drying method followed by two-step reduction process. The reduction process and sintering behavior of the W-Re powders and the DC emission properties of the W-Re mixed matrix dispenser cathodes have been studied. Porous microstructure for the W-Re mixed powders was developed during the hydrogen reduction process. With the increase of the rhenium content in the W-Re powders, the grain size of the matrix decreased dramatically and the sintering temperature has to be increased correspondingly in order to obtain appropriate apparent porosity. W-75at%Re mixed matrix cathode demonstrates the highest electron emission among the W-Re mixed cathodes studied, with direct current density reaching 10.73 A/cm² at a temperature of 1000 °C.