Experimental investigation of microstructure and mechanical properties of β-SiC with various sintering additives supplemented by first-principles calculations

β-SiC ceramics were prepared by spark plasma sintering at 2200 °C with Y 2 O 3 , MgO , and CeO 2 as sintering additives. Al 2 O 3 was doped based on the above oxides to form a two-component sintering additive to carry out a comparative analysis. The effects of these additives on the microstructure, bulk density, and Vickers hardness of β-SiC were systematically studied. The mechanical properties of the single-component samples were superior to those of the two-component samples. Notably, the single-component sample with Y 2 O 3 , addition exhibited the highest density (98.69 %) and hardness (27.1 GPa), which can be attributed to the appropriate growth of the grains in the single-component sample with Y 2 O 3 . Additionally, the principle of lattice reduction in SiC ceramics was explored using first-principle calculations, further highlighting the advantage of Y 2 O 3 as a single additive for the high-temperature sintering of SiC ceramics.