Effect of addition of tartaric acid on synthesis of boron carbide powder from condensed boric acid-glycerin product

摘要

The effect of the addition of tartaric acid on the synthesis of boron carbide (B_4C) powder from a condensed boric acid (H_3BO_3)-glycerin product was investigated in this study. The condensed product was prepared by dehydration condensation after directly mixing equimolar amounts of H_3BO_3 and glycerin with the addition of 0-50 mol% tartaric acid (based on glycerin), which was followed by thermal decomposition in air to obtain a precursor powder from which excess carbon had been eliminated. The dispersion state of the boron oxide (B_2O_3) and carbon components in the precursor prepared from the condensed product with 25 mol% tartaric acid added was finer than that without tartaric acid added, in which both precursors had a three-dimensional bicontinuous B_2O_3/carbon network structure. The complete formation of crystalline B_4C powder was achieved at 1250 °C within a shorter heat treatment time for the precursor with a fine dispersion state. The synthesized B_4C powders became fine owing to the increased number of nucleation sites.