Structural-Phase State and Properties of SiC Ceramics Obtained by Ultrasound-Assisted Liquid-Phase Sintering with Eutectic Additives

This study proposes an experimental charge composition for sintering carbide ceramics with additives forming a liquid phase: MnO 2.5 wt. % + Al2O3 2.0 wt. % + SiC 91.0 wt. % + SiO2 4.5 wt. %. The results of the structural-phase state and physical-mechanical properties of SiC ceramics obtained by ultrasound-assisted liquid-phase sintering with eutectic additives are presented. Densification with the participation of the liquid phase formed by SiO2, SiO, Si and MnO led to the formation of equiaxed grains with an average size of <= 10 mu m. The formation of the ceramic microstructure based on silicon carbide using eutectic additives made it possible to choose a composition that provided a decrease in the sintering temperature to 1800 degrees C. The main phase components of the synthesized ceramics were modification of the ring radical of silicate Si3O6, silicon dioxide SiO2, and anorthoclase (SiAl)O-4. The resulting material based on silicon carbide with a grain size of 10 mu m with the addition of 9 wt. % eutectic additive, after firing in a weakly reducing CO atmosphere at 1800 degrees C and holding for 2 h, has the following controlled indicators: ultimate strength in bending 440 +/- 20 MPa, microhardness (HV) 30 GPa. This is promising for use as an armored material and for obtaining materials with high physical and mechanical properties at significantly lower energy, resource, and material costs.