PHYSICOCHEMICAL INVESTIGATION OF THE REACTION OF COMPONENTS OF THE Si-Al-O-N-Ti SYSTEM IN THE Si_3N_4-Al_2O_3-AlN-SiO_2-TiN-TiO_2 REGION II. SUBSYSTEMS Si_3N_4-AlN, TiN-AlN, Al_2O_3-AlN

摘要

The reaction of components of the Si-Al-O-N-Ti system in its elements Si_3N_4-AlN, TiN-AlN, and Al_2O_3-AlN was investigated by differential thermal and x-ray diffraction analysis. It was established that upon hot pressing mixtures of Si_3N_4 and AlN (up to approx 1950 deg C) free silicon is formed by the decomposition of Si_3N_4, which reacts with oxygen present as an impurity to form SiO. When TiN reacts with AlN a phase with the spinel structure (Al_(23)O_(27)N_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_2O_3 with AlN. In this case a eutectic between Al_(23)O_(27)N_5 and Al_2O_3 is observed.