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

Abstract

Ultrahigh-temperature ceramics have been investigated for their high melting points and outstanding mechanical properties. Among these ceramic materials, ZrB 2 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 ZrB 2 is oxidized, two phases of oxide are produced on the surface of ZrB 2 : ZrO 2 and B 2 O 3 , which degrade the thermal and mechanical properties of ZrB 2 . In this study, a novel method is developed for the fabrication of core-shell-structured ZrB 2 @SiC composite particles to enhance the anti-oxidation properties of ZrB 2 with a fully covered SiC layer through the sol-gel process and carbothermal reduction. Using the sol-gel process with tetraethyl orthosilicate, core-shell ZrB 2 @SiO 2 particles are fabricated, and an amorphous phased shell is seen in the X-ray diffraction pattern. Thereafter, ZrB 2 @SiO 2 is transformed into ZrB 2 @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 ZrB 2 @SiC composite particles are successfully fabricated. • ZrB 2 @SiC nanoparticle had been fabricated through sol-gel and carbothermal reduction. • Pretreatment with acid solution removed oxygen impurity and made -OH bond for SiO 2 . • Carbothermal reduction was carried out to make SiC without the reaction with ZrB 2 • ZrB 2 @SiC nanoparticle can be applied for the refractory and thermal protection.