Synthesis of boron carbide from boric oxide-sucrose gel precursor

A simple method was developed to synthesize boron carbide from a boric oxide-sucrose gel precursor. This gel precursor was prepared at 873 K. Upon heating under ultra high pure argon cover gas at 1773 K for 3 h, it was found to yield boron carbide. The precursor and the final product were both characterized by X-ray diffraction, chemical assay (for boron and carbon), scanning electron microscopy and particle size distribution. Conditions most suitable for the preparation of the precursor were optimized. A gel-pyrolysis procedure which gives a very high yield of boron carbide (~ 60%) is reported for the first time in this study. The free residual carbon in the final product was lowered to 3.5%. Further this study clearly brings out the fact that the use of sucrose as a gel forming agent has definite advantages over the use of other carbon sources.