This article describes spark plasma sintering of ceramics based on silicon carbide with nanoadditives, as follows: MnO_nano 5.5 wt. % + Al₂O_3nano 2.0 wt. % + SiC_nm (37–57 wt. %) + SiC_µm (31–51 wt. %) + SiO_2µm 4.5 wt. %. Sintering was carried out at 2000 °C. The diffraction pattern of the analyzed sample showed the presence of silicon carbide with a hexagonal crystal lattice. Residual amounts of rhombohedral SiC, α-Fe, and a solid solution of silicon in iron were also found. The method of thermogravimetric analysis established the change in mass, heat flow, temperature of the samples, and the change in the partial pressures of gases during the experiment. Samples obtained by SPS show a higher density of the material at the level of 3.3 g/cm³, average mechanical strength of 454 MPa, and microhardness of 35 GPa, compared with samples obtained by liquid-phase sintering. The SPS method also made it possible to obtain materials with a higher density (by 8%) and practically no significant crystal growth compared to samples obtained by liquid phase sintering. The results of the study facilitate the achievement of a combination of new approaches to the design of compositions and the technology of manufacturing SiC ceramics, which significantly expands their areas of application.

Silicon carbide (SiC) ceramics are among the most attractive materials for lightweight armor because they combine low density (3.0–3.2 g/cm³), high hardness, and high thermal and chemical stability; however, their densification remains challenging because of strong covalent bonding and low self-diffusion. This review analyzes the main sintering routes used for armor-grade SiC ceramics, including solid-state sintering, liquid-phase sintering, hot pressing, gas-pressure sintering, hot-isostatic pressing, ultra-high-pressure sintering, two-step sintering, and spark plasma sintering, together with additive systems based on B, C, Al₂O₃, Y₂O₃, MgO, CaO, and rare-earth oxides. Reported data show that solid-state sintering typically requires 2100–2300 °C and yields 90–95% relative density, whereas hot pressing and liquid-phase sintering achieve 96–99% density at lower temperatures, generally with a flexural strength of 350–800 MPa, fracture toughness of 3.5–7.0 MPa·m^1/2, and hardness of 20–30 GPa. Among the reviewed methods, spark plasma sintering provides near-theoretical density (≥99%) together with the most favorable combination of strength (up to 850 MPa) and hardness (up to 35 GPa). Overall, liquid-phase sintering and spark plasma sintering offer the most favorable balance between densification, microstructural control, and armor-relevant mechanical performance.

Catalysts for the synthesis of higher α-olefins by the atmospheric-pressure cracking of paraffins in the temperature range of 450–570°C have been proposed. Natural zeolite from the Shankanay deposit in Almaty oblast was modified with inorganic and organic acids and a tungsten 12-heteropoly acid (HPA). The modification enhances the paraffin cracking ability; the best result was achieved with the tungstic 12-HPA. The strength and concentration of acid sites of the catalysts were determined by the IR measurement of CO adsorption. The HPA-promoted catalysts were found to contain a large amount of strong acid sites. The modification of natural zeolite with HPA leads to an increase in the total surface area from 22 to 257 m²/g. TEM images show the presence of ordered HPA structures of a few nanometers in size in zeolite pores. The abnormal rise in catalytic activity is associated with the emergence of new nanosized HPA structures on the zeolite surface.