Preparation of CaB₆ powder via calciothermic reduction of boron carbide

Abstract

The method of calciothermic reduction of B₄C was proposed for preparing CaB₆. The phase transition and morphology evolution during the reaction were investigated in detail. The experimental results reveal that Ca first reacts with B₄C to generate CaB₂C₂ and CaB₆ at a low temperature and that the CaB₂C₂ subsequently reacts with Ca to produce CaB₆ and CaC₂ at a high temperature. After the products were leached to remove the byproduct CaC₂, pure CaB₆ was obtained. The grain size of the prepared CaB₆ was 2–3 μm, whereas its particle size was 4–13 μm; it inherited the particle size of B4C. The residual C content of the product was decreased to 1.03wt% after the first reaction at 1173 K for 4 h and the second reaction at 1623 K for 4 h.

Keywords

borides / carbides / particle size / powders / calcium hexaboride

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