Synthesis of ZrB₂-SiC Composite Powder by Microwave and Molten-Salt Co-assisted Boro/Carbothermal Reduction Method

ZrB₂-SiC composite powder was prepared by microwave and molten-salt co-assisted boro/carbothermal reduction method with ZrO₂, SiO₂, B₄C and activated carbon as reactants, and with NaCl and KCl as molten-salt. The effects of reaction temperature, reaction time, B₄C and molten-salt content on the phase composition and microstructure of the product were investigated. The results show that with the increase of reaction temperature, reaction time, B₄C content and molten-salt content, the synthetic reaction of ZrB₂ and SiC occurred more completely, and the diffraction peaks of ZrB₂ in the product were getting stronger. When the reaction temperature was 1 200℃, reaction time was 20 min, salt to reactant mass ratio was 2:1 and the molar ratio of B₄C to ZrO₂ was 0.8, the pure-phased ZrB₂-SiC composite powder with average grain size of 38 μm was obtained, where ZrB₂ had a one-dimensional rod-like structure with a diameter of about 1.35 μm and an average length to diameter ratio over 10.