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UDC 621.762It is established that the cooling rate after hot pressing controls the crystallization and decrystallization in Si 3 N 4 -TiO 2 (TiH 2 ) composites. The critical cooling rate is 30 deg/min for Si 3 N 4 -TiO 2 composites and 50 deg/min for Si 3 N 4 -TiH 2 composites. It is shown that conductivity responds to the microstructural evolution of the composites as defect centers appear. The defects are located at trapping levels of (0.4 ± 0.05)-(1.3 ± 0.05) eV and differ in mutually perpendicular directions. The best combination of properties is shown by the composites with a monotrapping level with an activation energy of 0.8 ± 0.05 eV. These energy levels supposedly belong to the thin layer of amorphous silicon. The nascent defects are probably point defects or an association of point defects because of the low sensitivity of mechanical properties and strong response of conductivity to the cooling rate.

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