锌——镉系中镉蒸气压的测定  

The Determination of Cadimium Vapour Pressure In Zn-Cd System

作　　者：夏丹葵[1] 戴永年[1] 李淑兰[1] 

机构地区：[1]昆明工学院真空冶金研究所

出　　处：《昆明理工大学学报（自然科学版）》1989年第3期77-82,共6页Journal of Kunming University of Science and Technology(Natural Science)

摘　　要：用圆柱形坩埚测定蒸气压时,考虑到坩埚壁对蒸气分子的阻力,以及考虑到所有离开蒸发表面的蒸气分子不是全部都能凝结成凝聚态,而其中有一部分将重新返回到蒸发表面,考虑到上述这些因素后,经推算得到测定蒸气压的理论公式为:1/g=c/p(1/a-1)+c/p·1/k,公式表现为直线函数1/g=f(1/k),利用此式根据大量试验在高真空下测定蒸发速率值可以相当精确地计算蒸气压P. 本文利用上述原理得到了598.15°K——800.15°K温度范围内Zn—Cd系中镉的蒸气压,并且导出了Zn—Cd系中锌、镉活度系数与温度、浓度关系的数学模型.实验结果表明Zn—Cd系与拉乌尔呈现出不大的正偏差.The vapour pressure of Cadimium in Zn-Cd alloy of various compositions at different temperatures were measured by means of free evaporation of cadimium vapour under vacuum conditions in an electrically heated measuring apparatus made by ourselves. Two factors effecting the accuracy of vapour pressure measurement had been considered when cylindrical crucible was used as the melt's container: (1) the rebounding effect of the crucible wall on the vapour atoms colliding with the wall; (2) only a part of vapour atoms evaporating from the melt' s surface condensed again into the liquid phase. On the basis of the consideration mentioned above,we have adopted a new formula for vapour pressure determining as follows : which shows a linear relationship between 1/g and 1/k. with the help of this formula, vapour pressure of cadimium can be calculated accuratelly by determining the evaporation rate under high vacuum conditions. The vapour pressure of cadimium in Zn-Cd binary systems in temperature ranging from 598—800 ° k were attained by making use of the principles stated above. And the mathematic models which show the relationship between the acticity coefficients of zinc and cadimium and their concentrations as well as their temperatures were deduced for Zn-Cd system. The calculated results show that the thermodynamic behaviours of cadimium and zinc in Zn-Cd rystems deviate slightly positively from Raoult' s laws.

关 键 词：钭合金 蒸汽压 数学模型 

分 类 号：T-55[一般工业技术]