Synthesis of ZrB2@SiC composite particle through sol-gel and carbothermal reduction

Ultrahigh-temperature ceramics have been investigated for their high melting points and outstanding mechanical properties. Among these ceramic materials, ZrB2 exhibits good thermal properties and chemical resistance owing to its strong combination of ionic and covalent bonds, making it a promising candidate in various industrial fields. However, when ZrB2 is oxidized, two phases of oxide are produced on the surface of ZrB2: ZrO2 and B2O3, which degrade the thermal and mechanical properties of ZrB2. In this study, a novel method is developed for the fabrication of core-shell-structured ZrB2@SiC composite particles to enhance the anti-oxidation properties of ZrB2 with a fully covered SiC layer through the sol-gel process and carbothermal reduction. Using the sol-gel process with tetraethyl orthosilicate, core-shell ZrB2@SiO2 particles are fabricated, and an amorphous phased shell is seen in the X-ray diffraction pattern. Thereafter, ZrB2@SiO2 is transformed into ZrB2@SiC by adding 7 wt% carbon. It has a distinct SiC crystal structure, and its shell thickness is measured as 5.2 nm. High-resolution transmission electron microscopy images and selected area electron diffraction patterns confirm that core-shell-structured ZrB2@SiC composite particles are successfully fabricated.