钡-钨阴极的组织特性与热电子发射性能  

Microstructure characterization and thermionic emission performance of barium-tungsten cathode

作　　者：王子玉 尚吉花 杨新宇[1] 张久兴[1] Wang Ziyu;Shang Jihua;Yang Xinyu;Zhang Jiuxing(School of Material Science and Engineering,Hefei University of Technology,Hefei 230009,China)

机构地区：[1]合肥工业大学材料科学与工程学院,合肥230009

出　　处：《强激光与粒子束》2021年第5期29-36,共8页High Power Laser and Particle Beams

基　　金：国家自然科学基金项目(51501051)。

摘　　要：利用正交试验探讨了放电等离子技术工艺参数(温度、压力、保温时间)对钡-钨(Ba-W)阴极中的W的孔隙度的影响规律,获得了孔隙率在23%~30%内变化时所需要的最佳工艺参数。在此基础上,制备出了具有不同孔隙度的球形W基体和普通不规则的W基体。研究表明:球形多孔W颗粒间堆积、排列有序,无闭孔,孔径分布集中而均匀,在26.3%的孔隙度下中值孔径为1.41μm;机械性能方面,球形钨粉基体维氏硬度低于传统普通不规则钨多孔体。在脉宽10μs、频率1000 Hz的条件下,阴极脉冲发射电流密度随着孔隙度的增大,先增大后减小。当基体孔隙度为26.3%时,阴极电流发射密度最大,在1050℃,偏离点发射电流密度可达24.62 A/cm^(2),零场发射电流密度为7.62 A/cm^(2),功函数为1.95 eV。The effect of the parameters(sintering temperature,pressure,holding time)of spark plasma sintering technique on the W porosity of Ba-W cathode was studied by orthogonal method.When the W porosity varied in the range of 23%−30%,the corresponding process parameters were obtained.On this basis,the spherical and traditional irregular W matrix with different porosity were sintered.The results show that the spherical porous W particles were packed and arranged orderly,and the pore size distribution was concentrated and uniform.When the porosity of spherical W was 26.3%,the size of the median pore was 1.41μm.The vickers hardness of spherical tungsten matrix was lower than that of conventional irregular tungsten matrix.Under the condition of pulse width 10μs and frequency 1000 Hz,the impulse current density of Ba-W cathode increased at first and then decreased with the increase in porosity.The maximum current density belonged to the Ba-W cathode with the matrix porosity of 26.3%.At 1050℃,the off-point emission current density of Ba-W cathode reached 24.62 A/cm^(2),the corresponding zero-field current density and workfunction were 7.62 A/cm^(2)and 1.95 eV,respectively.

关 键 词：放电等离子技术 钡-钨阴极 球形钨粉 孔隙度 热发射性能 

分 类 号：TF125[冶金工程—粉末冶金]