Structure and Properties of Spark Plasma Sintered SiC Ceramics with Oxide Additives

Abstract

This article describes spark plasma sintering of ceramics based on silicon carbide with nanoadditives, as follows: MnOnano 5.5 wt. % + Al2O3nano 2.0 wt. % + SiCnm (37–57 wt. %) + SiCµm (31–51 wt. %) + SiO2µm 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.