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碳热过程的热力学分析表明,系统压力为100 Pa时,生成Al4O4C与Al4C3以及Al4O4C与C结合生成Al4C3的初始温度分别为1690,1711,1472 K;碳热-氯化过程的热力学分析表明,在101 Pa,1500 K时,氧化铝直接碳热-氯化的吉布斯自由能为-20.041 kJ;系统压力为100 Pa时,Al4O4C,Al4C3以及Al2O3联合Al4O4C,Al4C3参与氯化反应的初始温度分别为1459,1378,1416 K。实验结果显示:碳热过程在50~100 Pa、高于1693 K时,Al4O4C与Al4C3开始生成且含量随着温度的升高而增加;随着温度的继续升高或系统压力的减小,Al2O3及Al4O4C碳热转化为Al4C3。在50~100 Pa,1693 K时进行了实验,证明了该过程没有发生碳热-氯化反应。在70~150 Pa,1753~1853 K的范围时进行实验,均得到金属铝,说明要发生碳热-氯化反应必须先发生氧化铝与碳的碳热反应,即生成Al4O4C与Al4C3。
The thermodynamic analysis of the carbothermal process shows that the initial temperatures of Al4O4C and Al4C3 and Al4O4C combined with C to form Al4C3 are 1690, 1711 and 1472 K respectively at the system pressure of 100 Pa. The thermodynamic analysis of the carbothermal-chlorination process shows that at 101 Pa, 1500 K, the Gibbs free energy of direct thermal carbonation-chlorination of alumina is -20.041 kJ. When the system pressure is 100 Pa, the initial temperatures of Al4O4C, Al4C3 and Al2O3 combined with Al4O4C and Al4C3 are respectively 1459, 1378, 1416 K. The experimental results show that when the temperature is 50-100 Pa and higher than 1693 K, Al4O4C and Al4C3 start to form and the content increases with the increase of temperature. With the increase of temperature or the decrease of system pressure, the content of Al2O3 And Al4O4C carbothermal conversion to Al4C3. Experiments were carried out at 50-100 Pa and 1693 K, demonstrating that no carbothermal-chlorination reaction took place in this process. In the range of 70-150 Pa and 1753-1853 K, metal aluminum was obtained, which indicated that the carbothermal reaction between alumina and carbon had to take place before the carbothermal-chlorination reaction occurred, that is, Al4O4C and Al4C3 were formed.