Synthesis and Characterization of the Properties of (1-x)Si 3 N 4 -xAl 2 O 3 Ceramics with Variation of the Components.

The aim of this paper is to study the effect of variation in the component ratio of (1-x)Si 3 N 4 -xAl 2 O 3 ceramics on the phase composition, strength and thermal properties of ceramics. To obtain ceramics and their further study, the solid-phase synthesis method combined with thermal annealing of samples at a temperature of 1500 °C typical for the initialization of phase transformation processes was used. The relevance and novelty of this study lies in obtaining new data on the processes of phase transformations with a variation in the composition of ceramics, as well as determining the effect of the phase composition on the resistance of ceramics to external influences. According to X-ray phase analysis data, it was found that an increase in the Si 3 N 4 concentration in the composition of ceramics leads to a partial displacement of the tetragonal phase of SiO 2 and Al 2 (SiO 4 )O and an increase in the contribution of Si 3 N 4 . Evaluation of the optical properties of the synthesized ceramics depending on the ratio of the components showed that the formation of the Si 3 N 4 phase leads to an increase in the band gap and the absorbing ability of the ceramics due to the formation of additional absorption bands from 3.7-3.8 eV. Analysis of the strength dependences showed that an increase in the contribution of the Si 3 N 4 phase with subsequent displacement of the oxide phases leads to a strengthening of the ceramic by more than 15-20%. At the same time, it was found that a change in the phase ratio leads to the hardening of ceramics, as well as an increase in crack resistance.