Synthesis of zirconium carbide whiskers by a combination of microwave hydrothermal and carbothermal reduction

Zirconium carbide (ZrC) whiskers were successfully synthesized by a combination of microwave hydrothermal (MH) and carbothermal reduction . The precursors of ZrC whiskers were produced by MH, subsequently carbothermally reduced to ZrC whiskers at 1100–1600   °C in an Ar atmosphere. Effects of the reduction temperature and precursors with various carbon/zirconium (C/Zr) molar ratios on the synthesis of ZrC whiskers were investigated. The results showed that the carbothermal reduction occurred at 1100   °C, and terminated at a relatively low temperature (1400   °C). When the reduction temperature was 1500   °C and the C/Zr molar ratio was 5:1, the ZrC whiskers with the largest aspect ratio and the most uniform distribution were produced. The whiskers exhibited the diameters of 0.1–2   µm and the lengths of 5–30   µm. The synthesized ZrC whiskers with a single crystalline phase displayed cylindrical and pagoda-like morphologies. The growth of ZrC whiskers was considered to be governed by the Ostwald ripening and S-L-S mechanism.