Effects of high-energy ball milling and reactive spark plasma sintering on the densification, microstructure, and mechanical properties of ultra-fine and X-ray pure ZrB2-SiC composites

The effects of high-energy ball milling (HEBM) and reactive spark plasma sintering (R-SPS) on the densification, microstructure, and mechanical properties of ultra-fine and X-ray pure ZrB2-SiC composites were analyzed. For this purpose, a high-energy milled ZrC, B4C, and Si powder mixture was densified using spark plasma sintering (SPS), with or without pre-heat treatment. The pre-heat treatment was performed at 1600°C without pressure to synthesize the ZrB2-SiC nanopowder mixture before densification. Dense ZrB2-SiC composites with relative densities of 99.2 % and 98.86 % were fabricated for samples without and with pre-heat treatment, respectively, at a low sintering temperature of 1650°C under 40 MPa pressure. The beneficial effects of HEBM and R-SPS on the densification, microstructure, and mechanical properties were clearly identified. This method offers a new approach to densify X-ray pure ZrB2-SiC composites with ultra-fine microstructure, high mechanical properties, and low cost due to the affordability of raw materials and low sintering temperature.