复合稀土钼材料次级发射性能  

Secondary electron emission property of composite REO-Mo materials

作　　者：刘伟[1] 王金淑[1] 高非[1] 任志远[1] 周美玲[1] 

机构地区：[1]北京工业大学材料科学与工程学院教育部功能材料重点实验室,北京100124

出　　处：《中国有色金属学报》2009年第9期1636-1641,共6页The Chinese Journal of Nonferrous Metals

基　　金：国家高技术研究发展计划资助项目(2006ZZ03Z524;2008AA031001);国家自然科学基金项目(50801001)

摘　　要：利用溶胶-凝胶法制备稀土氧化物掺杂钼粉,随后利用放电等离子体烧结法将该粉末制备成稀土钼金属陶瓷材料,利用SEM、DTA、电子发射性能测试等方法对样品次级电子发射性能进行研究。结果表明:稀土氧化物均匀掺杂和组织的细化有利于材料发射性能提高,但不能降低其激活温度;经过高温氢气处理,样品的真空激活温度大幅降低,发射系数提高;稀土氧化物易吸收水分和气体的特性导致后续真空激活过程中阴极表层钼氧化,而高温氢气处理消除了样品中多余的水分和气体,保持了样品中金属与氧化物的相间分布状态,这是样品在活化前后发射性能发生变化的主要原因。The sol-gel doping method was utilized to dope the rare earth oxide powder into molybdenum.Such powders were sintered by spark plasma sintering and traditional sintering combined with compaction method for fabricating REO-Mo cermet cathodes.SEM, DTA and electron emission property measurements were used to investigate the secondary electron emission properties of the materials.The results show that the emission performance of the materials can be enhanced by symmetrical distribution of rare earth oxides and the refinement of structure.However, such treatments can＇t reduce the activation temperature in vacuum.Compared with the un-treated samples, the obvious drop of activation temperature and increase of secondary electron yield occur in samples annealed at high temperature in hydrogen.The activation temperature decreases obviously, and the secondary electron emission yield is enhanced apparently.Such easy adsorption of moisture and gas in the REO lead to oxidation phenomena of molybdenum in the subsequent activation in vacuum.The hydrogen annealing technology eliminates the excess moisture and gas and retain the distribution of REO in molybdenum.This is the main reason of variation of secondary electron emission for un-treated samples and pre-activating samples.

关 键 词：稀土 钼 次级发射 烧结 

分 类 号：TF124[冶金工程—粉末冶金]