Study on Thermodynamic and Kinetics for Preparation of Vanadium-aluminum Alloy Based on Thermite Reaction
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摘要: 基于原子-分子理论建立了计算Al-V二元合金系结构单元质量作用浓度的热力学模型。利用文献报道的2 000、2 073、2 173、2 273 K下Al-V二元系的活度计算了生成Al8V5、Al4V反应的平衡常数, 并进一步得到其摩尔标准吉布斯自由能的表达式。同时采用TG-DSC热重同步热试验分析的方法, 研究了不同升温速率下, 铝热法合成钒铝合金反应机理及化学反应动力学。结果发现温度在660~690℃时, 差示扫描量热曲线各出现一个吸热、放热峰, 说明反应机理已发生改变。然后分别运用Kissinger法、Kissinger-Crane法求解铝热反应动力学参数, 建立动力学方程, 通过动力学计算得到表观活化能E=448.96 kJ/mol, 频率因子A=1.98×1029m/s, 反应级数n=0.83。Abstract: A thermodynamic model for calculating the mass action concentration of structural units in Al-V binary melts system was established based on the atom-molecule theory.The standard equilibrium constants for generating Al8V5 and Al4V were calculated using the activities of Al-V binary system respectively at 2 000,2 073,2 173 and 2 273 K reported on the literatures and the expressions of standard mole Gibbs free energy for the reactions were further obtained.Meanwhile,the mechanism and chemical kinetics for preparation of vanadium-aluminum alloy based on thermite reaction at different heating rates were investigated by TG-DSC.There was respectively an exothermic and endothermic peak on the differential scanning calorimetry curve (DSC curve) at 660~690 ℃ indicating the variation of reaction mechanism.The kinetics parameters of the thermite reactions were separately calculated by Kissinger and Kissinger-Crane equations and the kinetics equation was established. The apparent activation energy (E) was calculated to be 448. 96 kJ·mol-1,the frequency factor A=1.98×1029 m·s-1 and the reaction order n = 0.83.
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