Fabrication of Conductive Alumina by Gelcasting and Reduction Sintering
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 25oC to achieve gelation. The freshly gelled bodies were demolded, carefully dried, and then sintered at 1100oC, 1300oC, and 1550oC in nitrogen atmosphere. The holding times at 1100oC and 1300oC was 2 hours, while at 1550oC 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 3.6×106 +cm at 8.0wt.% monomer addition and sintering at 1550oC for 2 hrs. The effect of physical properties on electrical conductivity and the corresponding reaction mechanism were discussed in details.
T. Ohji, T. Sekino and K. Niihara
M. Takahashi et al., "Fabrication of Conductive Alumina by Gelcasting and Reduction Sintering", Key Engineering Materials, Vols. 317-318, pp. 657-660, 2006