Abstract

A complete thermodynamic analysis of chemical transformations in a BaO–B₂O₃–C system is performed in a temperature range of 1400–3000 K using the Terra software. Even before starting a reduction processes, the products of the reactions of boron and barium oxides are ortho-Ba₃B₂O₆ and barium metaborate BaB₂O₄ with crystallization temperatures of 1656 and 1378 K, respectively. The reduction with carbon of a mixture of the oxides with high (90BaO + 10B₂O₃) and low (35BaO + 65B₂O₃) contents of barium oxide is studied. In all cases, the reaction products can be carbide BaC₂, barium hexaboride BaB₆, and boron carbide B₄C. Barium carbide BaC₂ prevails in the smelting products of the processed mixture rich in barium oxide, whereas barium hexaboride predominates in the processed mixture rich in boron oxide. The formation of barium borates impedes reduction because of the decreased reactivity of BaO and B₂O₃. Being strong basic (BaO) and acidic (B₂O₃) oxides, they form stable compounds. The temperature of the onset of barium reduction to BaC₂ from BaO is 1500 K, and that from Ba₃B₂O₆ is 2200 K. The combined reduction of barium and boron occurs from barium borates to form BaB₆. For both mixtures, the formation of barium hexafluoride in the smelting products is detected at 2300 K. The presence of BaB₆ in the condensed phase indicates that a complex ferroalloy simultaneously containing boron and barium, which are known as efficient alloying and modifying elements, can be produced. The method of mathematical experiment planning is applied to a numerical simulation of the technology. Equations are derived for the dependences of the amounts of the formed phases on the BaO and B₂O₃ consumptions and temperature. The entire oxide composition range is studied in accord with the phase diagram of the BaO–B₂O₃ system. The equations make it possible to select the temperature and charge smelting conditions to achieve the required compositions of the condensed phases. The results of numerical experiments can be applied to the production of boron–barium alloys and the synthesis of high-temperature materials based on BaB₆, BaC₂, and B₄C.

中文翻译：

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BaO-B2O3-C 体系中的化学转化分析

摘要

使用 Terra 软件在 1400-3000 K 的温度范围内对BaO–B ₂ O ₃ –C 系统中的化学转化进行完整的热力学分析。甚至在开始还原过程之前，硼和氧化钡的反应产物是邻位 Ba ₃ B ₂ O ₆和偏硼酸钡 BaB ₂ O ₄，结晶温度分别为 1656 和 1378 K。高 (90BaO + 10B ₂ O ₃ ) 和低 (35BaO + 65B ₂ O ₃ )氧化物混合物的碳还原) 的氧化钡含量进行了研究。在所有情况下，反应产物可以是碳化物 BaC ₂、六硼化钡 BaB ₆和碳化硼 B ₄ C。碳化钡 BaC ₂在富含氧化钡的加工混合物的熔炼产物中占主导地位，而六硼化钡在加工过程中占优势。富含氧化硼的混合物。由于 BaO 和 B ₂ O _{3 的}反应性降低，硼酸钡的形成阻碍了还原。作为强碱性 (BaO) 和酸性 (B ₂ O ₃ ) 氧化物，它们形成稳定的化合物。钡从 BaO还原为 BaC ₂的开始温度为 1500 K，而从 Ba₃ B ₂ O ₆是2200 K。钡和硼的联合还原从硼酸钡形成BaB ₆。对于这两种混合物，在 2300 K 时检测到冶炼产物中六氟化钡的形成。凝聚相中BaB ₆的存在表明同时含有硼和钡的复合铁合金，这被称为有效的合金化和改性元素，可以被生产。将数学实验规划的方法应用于该技术的数值模拟。导出了形成相量对 BaO 和 B ₂ O ₃的依赖性的方程消耗量和温度。根据 BaO-B ₂ O ₃系统的相图研究整个氧化物组成范围。这些方程可以选择温度和炉料熔炼条件，以实现所需的凝聚相组成。数值实验结果可应用于硼钡合金的生产和基于 BaB ₆、BaC ₂和 B ₄ C的高温材料的合成。