Synthesis of Al8B4C7 ceramic powder from Al/B4C/C mixtures

Aluminium boron carbide (Al8B4C7) ceramic powder was synthesized via a solid state reaction method using Al, B4C and graphite powders as raw materials. The effects of synthesis temperature, carbon source (graphite and coke powder) and raw materials ratio on the phase transformation and micro-morphology of Al8B4C7 were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the optimized process for preparing the Al8B4C7 was 3 h sintering at 1600 °C in flowing argon atmosphere. Graphite was more appropriate than coke powder and carbon black as carbon source for synthesizing pure Al8B4C7, and 10 mol% excess of graphite resulted in higher purity of Al8B4C7. The stoichiometric amount of aluminium was essential for obtaining pure Al8B4C7, because second phase-Al4C3 would occur if excessive aluminium was used.