Seed-mediated growth of ZrC whisker and its toughening effect on ZrB₂-SiC-C ceramic

ZrC whiskers (ZrC_w) hold great promise in improving the strength and toughness of ultra-high temperature ceramics (UHTCs) without reducing their high-temperature stability. However, obtaining high quality ZrC_w has been challenging. Herein, we propose a novel method for easily synthesizing catalyst-free ZrC_w by seed-mediated growth technique, in which single crystal ZrC nanoparticle (ZrC_np) was used as seed crystal and ZrO₂-C-NaF mixture was used as precursor system. The effect of ZrC_np, NaF, and, synthesis temperature on the growth of ZrC_w was studied and the reaction process was analyzed based on the experimental results. The vapor-solid (V-S) growth mechanism was proved to be the dominating growing mechanism. Subsequently, the synthesized ZrC_w were added to a ZrB₂-SiC-C ceramic. Compared with the baseline, ZrC_w reinforced ZrB₂-SiC-C exhibited a remarkable combination of high strength and high toughness (592 ± 30 MPa and 7.1 ± 0.8 MPa·m^1/2). This novel synthesis method of ZrC_w may be applicable to the synthesis of other carbide ceramic whiskers and enrich the design of high performance ultra-high temperature ceramics.