新型钨铼混合基阴极的热电子发射性能  

Thermal Electron Emission Properties of Novel W-Re Mixed Matrix Cathodes

作　　者：赖陈 王金淑[1] 周帆[1] 王茜[1] 刘伟[1] 杨帆[1] 

机构地区：[1]北京工业大学,北京100124

出　　处：《稀有金属材料与工程》2016年第7期1871-1875,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51225402;51471006)

摘　　要：采用喷雾干燥结合两步氢还原法制备出W-Re混合粉末,并在此基础上通过压制、烧结和浸渍工艺制备出W-Re混合基浸渍型阴极。采用SEM、XRD、AES对W-Re混合基阴极的微观形貌、物相、表面活性元素进行表征分析,并用电子发射测试系统测试阴极在950~1050℃的脉冲电子发射性能。结果表明,铼的含量决定了阴极基体的物相,铼含量为75%(原子分数)的W-75Re阴极由Re3W单一物相组成,该阴极由于铼含量较高使得基体晶粒尺寸更细小,有利于活性自由钡的生成及其在阴极表面的扩散,从而W-75Re阴极具有相对较低的逸出功和较高的发射电流密度,其在1000℃b时的零场脉冲发射电流密度为14.03 A·cm^(-2),有效逸出功为1.902 e V。Tungsten-rhenium mixed powders were prepared by spray drying followed by a two-step hydrogen reduction method.With these powders,W-Re mixed metal matrix cathodes were prepared by processes of die pressing,sintering and impregnation.Thermal electron emission properties of the cathodes were tested using the self-prepared pulsed power testing system.SEM,XRD and AES were adopted to analyze the surface morphology,phase structure and surface chemical elements of the cathodes,respectively.Results show that the phase of the cathodes depends on the content of rhenium in the matrixes.The W-75 Re cathode（containing 75at% Re） is composed of Re_3 W singular phase.The emission testing results show that the W-75 Re cathode impregnated with 411 salt has the lowest work function of 1.902 e V and the highest zero field emission current density of 14.03 A·cm^-2 at 1000 ℃ among the prepared cathodes.It is possibly due to the high concentration of Re in the matrix,which results in fine grains in the matrix and is favourable to the formation of active Ba element and its diffusion on the cathode surface.

关 键 词：喷雾干燥 W-Re混合粉末 铼钨混合基阴极 脉冲发射 逸出功 

分 类 号：TN103[电子电信—物理电子学] TF125.241[冶金工程—粉末冶金]