Preparation of AlN-Al₂O₃ fibre composites using chemical vapour infiltration

Abstract

Vapour-phase reaction of AlCl₃ and NH₃ at 800 to 1000 °C was performed, and AIN produced was made infiltrate an Al₂O₃ fabric to form AlN matrix-Al₂O₃ fibre composites. The composites were characterized by observation of the appearances and by analyses with X-ray diffraction and scanning electron microscopy. The matrices of the composites prepared at above 900 °C had lustrous, smooth surfaces and revealed the preferred orientation toc-axis. The composite was constituted by the substrate layer and the surface layer. The fibres in the substrate layer were covered with radially-grown, columnar AlN grains with a maximum height of 15 μm. The surface layer was a dense AlN film 50 μm thick. Both the layers interlocked each other with mediation of the radially-grown AlN grains covering the fibres. The formation mechanism of the composites was deduced from the morphology. The wettability with a molten dental alloy was very low.