ABSTRACT The yield of boron carbide (B4C) synthesised by carbothermal reduction (CTR) is low (40–50%) owing to the inappropriate initial composition. In this paper, thermodynamic equilibrium simulations for effects of initial compositions on B4C synthesis were performed, while initial compositions on the quality and yield of B4C synthesised by CTR from B2O3-C mixture at atmospheric pressure were systemically investigated. The reaction mechanisms for B4C synthesis process were thermodynamically analysed. Moreover, growth mechanisms for B4C particles were speculated based on the thermodynamic and experimental results. The results show that the simulations agree well with experimental results, and optimal initial composition is 1.906 (B2O3/C weight ratio). Under optimal condition, B4C powder prepared at 1973 K is high-quality with well crystallinity, purity of 93.58% and yield of 90.05%. Additionally, the prepared B4C particles show two types of morphologies, aggregate of small equiaxed particles and needle-like particle, which are formed through different reaction mechanisms, respectively.

中文翻译：

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初始成分对碳化硼合成及相应生长机制的影响

摘要 由于初始成分不合适，通过碳热还原 (CTR) 合成的碳化硼 (B4C) 的产率很低 (40-50%)。在本文中，进行了初始组成对 B4C 合成影响的热力学平衡模拟，同时系统地研究了初始组成对 B2O3-C 混合物在常压下通过 CTR 合成的 B4C 质量和产率的影响。对B4C合成过程的反应机理进行了热力学分析。此外，基于热力学和实验结果推测了 B4C 颗粒的生长机制。结果表明，模拟结果与实验结果吻合良好，最佳初始成分为1.906（B2O3/C重量比）。在最佳条件下，1973 K制备的B4C粉体质量高，结晶度好，纯度93.58%，收率90.05%。此外，制备的 B4C 颗粒表现出两种形态，小等轴颗粒的聚集体和针状颗粒，它们分别通过不同的反应机制形成。