Spark plasma sintering of B₄C-SiC composites

B₄C-SiC composites were produced using spark plasma sintering (SPS) both reactively from B₄C-SiO₂-C starting powders and directly from B₄C-SiC at 1700 and 1750 °C under a pressure of 40 MPa. Densification, microstructure and mechanical properties of B ₄C-SiC composites were investigated. 98.8% relative density was obtained with the addition of Y₂O₃ in directly spark plasma sintered sample containing 10% SiC at 1750 °C for 5 min. In reactive spark plasma sintering, increasing SiC content resulted in a decrease in density because of the oxidation of SiC to SiO gas phase. The glassy phases formed with Y₂O₃ addition caused the Vickers hardness values to increase. SiC phase showed a homogenous dispersion in B₄C matrix.