Fabrication of Conductive Alumina by Gelcasting and Reduction Sintering

摘要

In this study, we propose a new process to fabricate electrically conductive alumina by gelcasting and reduction sintering. The process used the conventional gelcasting method except for varying amounts of monomer at 2.8, 5.5, and 8.0 wt.% relative to the weight of the slurry. In the plastic mould, the slurry was under in situ solidification for 3 hrs at 25°C to achieve gelation. The freshly gelled bodies were demolded, carefully dried, and then sintered at 1100°C, 1300°C, and 1550°C in nitrogen atmosphere. The holding times at 1100°C and 1300°C was 2 hours, while at 1550°C were 2, 4, and 6 hrs. The sintered alumina body was characterized by electrical property, X-ray diffraction, and scanning electron microscopy. Results showed that monomer additions and sintering schedule significantly affect in lowering electrical resistance. The low value was 3.6×10{sup}6 Ωcm at 8.0wt.% monomer addition and sintering at 1550°C for 2 hrs. The effect of physical properties on electrical conductivity and the corresponding reaction mechanism were discussed in details.