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Abstract ZrB 2 -SiC composite powders were synthesized through one-step reduction process of ZrO 2 , B 4 C, carbon black, silicon or silica under flowing argon. Effects of B 4 C contents, calcination temperatures and different silicon sources on the phase composition and morphology were investigated. Combining the X-ray diffraction (XRD) results and scanning electron microscope (SEM) images, the spherical ZrB 2 -SiC powders ranging from 100 nm to 300 nm would be prepared with silicon at 1500 °C for 60 min when n(B)/n(Zr) was at 2.4. As using silica as the raw material, the obtained ZrB 2 and SiC particles in the powders exhibited different shapes and sizes. The SiC grains were uniformly formed among the ZrB 2 grains. [ABSTRACT FROM AUTHOR]

ZrB 2 powders were successfully prepared via carbothermal reduction of ZrO 2 with H 3 BO 3 and carbon black under flowing argon. By introducing SiC species into reaction mixtures, the effects of SiC addition on phase composition and morphology of ZrB 2 powders thermally treated at different temperatures were investigated. The resultant samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). The highly pure ZrB 2 with the mean size of 5 µm could be obtained at 1600 °C for 90 min and the grains presented columnar shapes. After addition of SiC, ZrB 2 revealed relatively better crystallinity and finer particle size. Regular columnar ZrB 2 grains ranging from 1 to 2 µm were seen existing after reaction at 1500 °C for 90 min. [ABSTRACT FROM AUTHOR]

ZrB 2 -SiC powders with different amounts of SiC (10–30 wt%) were in-situ synthesized at 1600 °C for 90 min in Ar atmosphere. Effects of SiC addition on the formation of ZrB 2 via carbothermal reduction of ZrO 2 , H 3 BO 3 and carbon black were investigated. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and transmission electron microscope (TEM). The grain size of ZrB 2 in final powders decreased with adding SiC. Columnar ZrB 2 and granular SiC were combined interactively when the SiC content was 25 wt%. Layer-like hexagonal SiC was obtained in the product containing 30 wt% SiC, whereas the ZrB 2 grain growth was strongly inhibited. Furthermore, the growth mechanisms of ZrB 2 and SiC were studied. [ABSTRACT FROM AUTHOR]