Pulsed electric current sintering of MoO and the neutron irradiation tests

Suematsu, Hisayuki*; Seki, Misaki  ; Nakayama, Tadachika*; Nishikata, Kaori  ; Nanko, Makoto*; Suzuki, Tatsuya*; Tsuchiya, Kunihiko 

Pulsed electric current sintering (PECS) of MoO was carried out for a high density target to produce Tc from Mo in a nuclear reactor. The green compacts of MoO were heated in a PECS apparatus with a heating rate of 100 C/min to 450 - 550 C in vacuum and changing the pressurization profile from 0 to 40 MPa. After two step pressurization for sintering at 550 C, the sintered MoO bulk had a relative density of 94%, which was higher than that of one step pressurization. Direct temperature measurements near the sample were carried out. The results indicated that the sample temperature was higher for the two step than for the one step pressurization even in the same die temperature experiments. By the low pressure in two step pressurization, it was thought that open pores remained in the sintered body to reduce MoO in vacuum. This oxygen depleted MoO grains showed low electrical resistivity and formed a current path in the sintered body to increase the temperature to increase the relative density.