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The methods of X-ray diffraction, Fourier transform infra-red spectroscopy (FTIR), X-ray microanalysis, electron microscopy, BET and cation exchange capacity (CEC) were used for investigation of the structural-phase transformations in bentonite under the influence of hydrochloric acid and temperature treatment (100-800ºC). It is established that in HCl medium during temperature treatment, dehydration and dehydroxilation of montmorillonite occur. The presence of gypsum and barium chloride results in an intercalation of interlayer space of montmorillonite by Ca and Ba ions Temperature treatment of intercalated montmorillonite leads to the formation of pores

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The process of carbothermal reduction of Al2O3 in a nitrogen flow at temperatures of 1450 and 1600ºC has been studied. It was established that the powder synthesized at 1450ºC is a mixture of Al2O3 and AlN particles and that the powders synthesized at 1600ºC are mixtures of AlN, AlON, and Al2O3. Amorphous and crystalline AlON films form on the surface of Al2O3 and AlN particles. Both synthesized powders contain unreacted residual carbon. In the stage of high-pressure sintering of specimens at a temperature of 1750ºC under a pressure of 7 GPa for 110 s, AlON decomposes into AlN and Al2O3. Residual graphite transforms into a crystalline graphite phase, which decreases the strength and increases the fracture toughness. The highest hardness of 19.5 GPa was achieved in the ceramics obtained from the powder synthesized at 1600ºC for 4 h, and the largest fracture toughness of ~7.2 MPa•m1/2 was achieved in the ceramics obtained from the powder synthesized at 1450ºC for 4h

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