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

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 degrees 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. (C)2011 The Ceramic Society of Japan. All rights reserved.