Synthesis and Characterization of ZrC, HfC, and Mixed ZrHfC Whiskers by Carbothermal Reduction

Ultra‐high temperature ceramic (UHTC) whiskers are promising candidates for mitigating thermal shock due to improved performance in air and agreeable coefficient of thermal expansion with matrix materials. However, challenges in synthesis of UHTC fibers and whiskers result in a lack of commercial availability. In this study, we expand upon a previously published carbothermal reduction method to synthesize ZrC, HfC, and, for the first time, mixed ZrHfC whiskers. Several characterization techniques were used to systematically investigate the influence of carbothermal reduction temperature and carbon‐to‐metal (C:M) loading ratio on key characteristics of the resulting materials. This includes whisker morphology, stoichiometry, and byproduct formation. In addition to identifying and characterizing a significant free carbon byproduct formation, findings reveal that whisker length can be controlled by adjusting the carbothermal reduction temperature within the range of 1400°C–1600°C, ZrC x stoichiometry varies with changing C:Zr loading ratio, and complex mixed ZrHfC compositions are possible to synthesize in whisker morphologies.