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

ZrC whiskers (ZrCw) 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 ZrCw has been challenging. Herein, we propose a novel method for easily synthesizing catalyst-free ZrCw by seed-mediated growth technique, in which single crystal ZrC nanoparticle (ZrCnp) was used as seed crystal and ZrO2-C-NaF mixture was used as precursor system. The effect of ZrCnp, NaF, and, synthesis temperature on the growth of ZrCw 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 ZrCw were added to a ZrB2-SiC-C ceramic. Compared with the baseline, ZrCw reinforced ZrB2-SiC-C exhibited a remarkable combination of high strength and high toughness (592 & PLUSMN; 30 MPa and 7.1 & PLUSMN; 0.8 MPa.m1/2). This novel synthesis method of ZrCw may be applicable to the synthesis of other carbide ceramic whiskers and enrich the design of high performance ultra-high temperature ceramics.