稀土镧钼热阴极材料表面镧元素的蒸发  

Evaporation of element La on surface of Mo-La_2O_3 cathode

作　　者：周文元[1] 张久兴[1] 刘燕琴[1] 万小峰[1] 周美玲[1] 左铁镛[1] 

机构地区：[1]北京工业大学新型功能材料教育部重点实验室,北京100022

出　　处：《中国有色金属学报》2004年第2期189-193,共5页The Chinese Journal of Nonferrous Metals

基　　金：国家重点基础研究发展规划资助项目(G1998061316)

摘　　要：从理论上计算了碳化Mo La2O3热阴极材料在不同温度下活性物质镧元素的蒸发速度,分析了镧元素蒸发对材料热电子发射及其稳定性的影响。计算结果表明:当温度为1623～1700K时,阴极中镧的扩散速度大于阴极表面镧的蒸发速度,Mo La2O3阴极表面单质La的生成和蒸发保持平衡,阴极发射稳定;当工作温度超过1700K,阴极表面镧的蒸发速度超过扩散速度,发射电流逐渐减少。测试了Mo La2O3阴极FU 6051电子管在不同温度时的发射性能,热力学理论计算结果较好地解析了实验结果。The evaporation rate of element La at different temperatures in carbonized Mo-La_2O_3 cathode were calculated according to thermodynamics theory. The results show that the diffusion rate is greater than the evaporation rate of La on cathode surface at the temperature range of 1 6231 700 K, so the formation and evaporation of La can remain balance and the emission current is stable, and that when the operating temperature is above 1 700 K, the evaporation rate of La exceeds its diffusion rate on the cathode surface so that the emission current decreases gradually. In addition, the emission properties of the FU-6051 tubes equipped with Mo-La_2O_3 cathodes were tested at different temperatures, and the experimental results confirme the thermodynamic calculation.

关 键 词：热电子发射 稳定性 蒸发 扩散 Mo-La2O3 热阴极材料 稀土 

分 类 号：TG146.45[一般工业技术—材料科学与工程] O462.1[金属学及工艺—金属材料]