Physicochemical Investigation of the Reaction of Components of the Si -- Al -- O -- N -- Ti System in the Si3N4 -- Al2O3 -- AlN -- SiO2 -- TiN -- TiO2 Region. Part 2. Subsystems Si3N4 -- AlN, TiN -- AlN, Al2O3 -- AlN

The reaction of components of the Si -- Al -- O -- N -- Ti system in its elements Si ^sub 3^N^sub 4^ -- AlN, TiN -- AlN, and Al ^sub 2^O ^sub 3^ -- AlN was investigated by differential thermal and x-ray diffraction analysis. It was established that upon hot pressing mixtures of Si^sub 3^N ^sub 4^ and AlN (up to 1950°C) free silicon is formed by the decomposition of Si ^sub 3^N^sub 4^, which reacts with oxygen present as an impurity to form SiO. When TiN reacts with AlN a phase with the spinel structure (Al^sub 23^O ^sub 27^N ^sub 5^), which can form only in the presence of excess oxygen, appears in addition to the initial components. Spinel is also produced by the reaction of Al ^sub 2^O^sub 3^ with AlN. In this case a eutectic between Al ^sub 23^O^sub 27^N^sub 5^ and Al^sub 2^O^sub 3^ is observed.[PUBLICATION ABSTRACT]