Low-temperature spark plasma sintering and mechanical properties of α-SiC ceramics without additives

Using granulated silicon carbide (SiC) powder and spark plasma sintering technology, α-SiC ceramics were fabricated at a low temperature of 1750 °C without sintering additives. This sintering temperature is at least 100 °C-200 °C lower than the temperature reported for the conventional sintering of pure SiC ceramics. The effects of sintering temperature, powder morphology, and particle size on the microstructure and mechanical properties of the SiC ceramics were investigated. Additionally, the low-temperature densification mechanisms under optimal sintering conditions were analyzed. Results showed that the SiC ceramics sintered at 1750 °C exhibited excellent properties, such as a Vickers hardness of 26.3 ± 0.6 GPa, bending strength of 461 ± 15 MPa, fracture toughness of 4.6 ± 0.1 MPa m^1/2, and average grain size of ∼1.1 μm. These findings provide an effective strategy for the low-temperature fabrication of dense, mechanically robust pure SiC ceramics.