部分酸化・反応焼結によるアルミナ/ムライト/炭化ケイ素配向ナノコンポジットの作製と特性

Abstract

Nanocomposites with nanoparticles dispersed as the second phase have been reported to have improved mechanical properties. In spite of this potential processing methods to produce these nanocomposites are not well established. In this study, Al2O3/mullite/SiC nanocomposites were prepared by the reaction sintering of green compacts prepared by slip casting of a mixture of SiC and Al2O3 powders. Here, the surface of the SiC particles was first oxidized to produce SiO2 and to reduce the core of the SiC particles, and then the surface SiO2 was reacted with Al2O3 to produce mullite. By applying a strong magnetic field during slip casting, the Al2O3/mullite/SiC nanocomposites were fabricated with Al2O3 oriented, but not with mullite, Al2O3 was oriented so that the c-axis of the crystal was parallel to the direction of the strong magnetic field. The density was low due to the agglomeration of SiC raw powder. The bead mill using fine zirconia beads of 50 μm was effective to disperse the agglomerated particles and succeeded in obtaining high-density Al2O3/mullite/SiC with no agglomeration of SiC nanoparticles. The bending strength was greatly improved by dispersing the particles, but such improvement was not observed by texturing.