Low-temperature synthetic route for boron carbide powder from boric acid-citric acid gel precursor

Abstract

Boron carbide powder was synthesized by sol-gel polycondensation of boric acid with citric acid. The starting materials of Serbian origin were dissolved in water and mixed homogeneously until a precomposite gel was formed, which was converted into cryogels after freeze-drying. Pyrolysing and subsequent heat treatment of these cryogels resulted in boron carbide materials. Characterization by nitrogen adsorption showed that the precomposite cryogels and the composite powders were micro and mesoporous materials with large surface areas. Materials have been analyzed by means of X-ray diffraction and scanning electron microscopy. The Rietveld refinement was employed to get the structural information of the synthesized powder. The results show that the obtained carbide powder is composed of nearly equiaxed particles of narrow size distribution.