窒化ケイ素微粉末の緻密化挙動及び粒成長に及ぼす相転移の影響

抄録

Fine and uniform silicon nitride powders having different α-content were prepared from commercial submicron powders by centrifugal sedimentation. The densified pre-sintered materials were fabricated from these powders by hot-pressing. The fine powders with similar particle size distribution showed the same densification behavior during hot-pressing. The microstructures of pre-sintered materials of the fine powders showed the fine and homogeneous microstructures, and the similar one irrespective of α content. The pre-sintered materials were annealed at 1800°C for 1h under 1MPa nitrogen atmosphere. The annealed material from the fine β powder showed the fine and homogeneous microstructure. On the other hand, the material from the fine α powder developed “in-situ composite” microstructure consisting of large grains and fine matrix grains by annealing. Because, the abnormal grain growth was caused by the α- to β-phase transformation during annealing. While, these results of the fine powders were compared with those of the commercial submicron powders.