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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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Introduction. In modern conditions, the combustibility of polymers plays a dominant role in the process of the appearance and spread of fires. This is because the extremely wide use of polymeric materials in all areas of the national economy. Due to the organic structure, the high content of carbon and hydrogen that make up the macromolecules of the polymers, they are extremely combustible. Combustion of polymers is accompanied by high temperature and flame propagation rate, as well as significant smoke generation and the release of a large number of toxic combustion products. Therefore, the search for new ways to reduce combustibility is one of the priority tasks in the creation and implementation of new polymer materials in various industries. Purpose. The aim of the work is the synthesis of fundamentally new complex compounds of transition metals, the study of their structure and properties, as well as predicting the possibility of their use to reduce the fire hazard of polymeric materials based on epoxy resins. Metods. Modern research methods are used in the work: X-ray diffraction, differential thermal and thermogravimetric analyzes, the method of quantum chemical calculations and IR spectroscopy. The ignition and self-ignition temperatures were determined by standard methods according to GOST 12.1.044-89 using metrologically certified equipment and calibrated measuring instruments. Results. By the direct interaction of the combustible organic amine pepa with inorganic salts of copper(II), a number of chelate complexes were obtained. By methods of x-ray phase analysis and IR spectroscopy, their structure was established. The results of quantum-chemical calculations of the complexation process showed that, as a result of the formation in the pepa–Cu(II) salt system, the chelate complexes [Cu(deta)H2O]SO4·H2O, [{Cu(deta)(H2O)(CO3)}2]·6H2O та [Cu(deta)(eda)]SiF6, the energy state of the chemically bonded pepa changes with respect to free molecules. In addition, the results of thermogravimetric studies and the measured ignition and self-ignition temperatures for pepa and complex compounds clearly showed that the process of bonding a combustible organic amine with a non-combustible inorganic salt into a solid complex ensures a decrease in the combustibility of nitrogen-containing hydrocarbon. All this is an extremely important prerequisite in the implementation of the complex mechanism of flame retardant action of transition metal salts. Conclusion. The results of the studies showed that complex compounds based on transition metal salts, and in particular copper(II), can be successfully used as flame retardants that can effectively reduce the fire hazard of nitrogen-containing synthetic polymers, including those based on epoxy resins.