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Influence of precursor preparation on the synthesis of boron carbide from glutinous rice flour

Boron carbide is a promising candidate for a variety of applications, including blasting nozzles, neutron moderators, and lightweight armor. Using of inexpensive and readily available starting materials which can react with boric acid to form B-O-C bonds, e.g., glutinous rice flour, is one of alternative means to produce high purity boron carbide powder at low temperature. In this study, boric acid and glutinous rice flour, boron and carbon sources, were used for synthesizing B4C powder by the carbothermic reduction. The mole ratios of boric acid to glutinous rice flour ranging from 1:1 to 2.5:1 were formulated and mixed by continuous stirring at 80℃ for 2 h to 8 h. The influence of reaction time during the mixing process on the phase formation of the synthesized powder was investigated. It was found that appropriate reaction time for condensation of 4 h facilitated the B4C phase formation during synthesis. The precursors were synthesized under Ar flow at 1350℃ to 1450℃ for 5 h without calcination. B4C powder with the purity of 90 wt% was successfully synthesized from this study. Chemical bonding, phase analysis, and morphology of the synthesized powder were identified by Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope, respectively. The influences of starting composition and synthesis temperature on the characteristics of the synthesized powders were also discussed. 