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 B4C–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.

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► B4C–SiC composites produced by using SPS for the first time.
► Reactive SPS, direct SPS and direct SPS+ sintering additive (Y2O3) are used to obtain composites.
► Some physical and mechanical properties of them are compared.
► Reactive SPSed composites showed lower physical and mechanical properties.
► Thermodynamical data are used to express the reasons of weak properties.