Spark plasma sintering and hot pressing of ZrB2–SiCW ultra-high temperature ceramics

Zirconium diboride (ZrB2)-based ultra-high temperature ceramics reinforced by SiC whisker were prepared by spark plasma sintering (SPS) and conventional hot pressing (HP). Dense materials were fabricated at 1600 °C by SPS and 1800 °C by HP. The densification behavior was investigated through the analysis of the HP and SPS shrinkage curves. The microstructures and mechanical properties were analyzed and compared in order to understand the influence of the two sintering techniques. The mechanical properties took full advantage of the addition of SiC whisker. Both materials exhibit high flexural strength and fracture toughness of >700 MPa and >6 MPam1/2, respectively. The main outcome of the present work is that when the ZrB2–SiCW ceramics composite was densified either by SPS or HP, the mechanical properties especially fracture toughness was higher than that of analogous monolithic and composites materials.