Effect of boron oxide/carbon arrangement of precursor derived from condensed polymer-boric acid product on low-temperature synthesis of boron carbide powder

摘要

The effect of the boron oxide (B₂O₃)/carbon arrangement of the precursor on the low-temperature synthesis of boron carbide (B₄C) powder was investigated in this study. The precursor was prepared by low-temperature heat treatment without thermal decomposition and subsequent pyrolysis in air of the condensed product formed from poly(vinyl alcohol) (PVA) and boric acid. The dispersion state of B₂O₃ particles in the carbon matrix of the precursor significantly affected the acceleration of the synthesis reaction. Crystalline B₄C powder with little free carbon was obtained by heat treatment at 1100°C, which was also the critical formation temperature, for 20 h in an Ar flow starting from a precursor with a B₂O₃/carbon structure homogeneously arranged at the nanometer scale.