微波烧结制备钨锇混合基扩散阴极及其发射性能  

Preparation and emission performance of tungsten-osmium mixed matrix dispenser cathode by microwave sintering

作　　者：刘伟[1] 胡志凯 李世磊 周帆[1] 杨韵斐[1] 张小可 谢元峰 王金淑[1] LIU Wei;HU Zhikai;LI Shie;ZHOU Fan;YANG Yunfei;ZHANG Xiaoke;XIE Yuanfeng;WANG Jinshu(Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China;GRIMAT Engineering Institute Co.,Ltd.,Bejing 101407,China)

机构地区：[1]北京工业大学材料与制造学部,北京100124 [2]有研工程技术研究院有限公司,北京101407

出　　处：《粉末冶金技术》2023年第3期199-209,共11页Powder Metallurgy Technology

摘　　要：采用固–液混合法制备出不同锇(Os)含量(原子数分数)的亚微米级钨锇混合粉体,通过微波烧结获得了孔道结构均匀的钨锇混合基扩散型阴极。电子发射测试结果表明,元素Os的加入使浸渍型钨基阴极的发射性能有明显提高。对比不同锇含量的混合基阴极,发现W-25Os阴极(Os原子数分数为25%)具有相对较低的逸出功和较高的发射电流密度,其在1100℃时脉冲发射电流密度为42.86 A·cm^(-2),斜率为1.40,发射电流密度是同等工作条件下传统钡钨阴极的1.7倍,达到了覆膜M型阴极的电子发射水平。W-25Os混合基阴极的有效逸出功最低为1.93 eV,有利于活性自由钡(Ba)的生成,表层元素摩尔比Ba:(W+Os)为0.83:1.00,比传统钡钨阴极中Ba:W(约为0.50:1.00)摩尔比有了明显提高。Submicron tungsten-osmium mixed powders with the different content of Os(atomic number fraction)were prepared by solid-liquid mixing method.The tungsten-osmium mixed matrix disperser cathodes with the uniform pore structure were obtained by microwave sintering.The electron emission testing results show that,the addition of Os obviously improves the emission performance of the impregnated tungsten-based dispenser cathode.The W-25Os cathode(Os atomic number fraction is 25%)exhibits the relatively low work function and high emission current density.At 1100 C,the pulse emission current density of the W-25Os cathode is 42.86 A-cm^(-2) with the emission slope of 1.40,which is 1.7 times of the conventional barium-tungsten dispenser cathodes under the same working conditions and up to the electron emission level of M-type cathodes.The W-25Os cathode shows the low effective work function as 1.93 eV,which is conducive to the generation of active free barium source.The molar ratio of surface elements Ba:(W+Os)is 0.83:1.00,which is significantly higher than that of the traditional barium tungsten cathode(about 0.50:1.00).

关 键 词：微波烧结 混合基阴极 锇 电子发射 功函数 

分 类 号：TF124[冶金工程—粉末冶金]