(北京工業(yè)大學 材料科學與工程學院 教育部功能材料重點實驗室，北京 100124)
摘 要: 利用溶膠−凝膠法制備稀土氧化物摻雜鉬粉，隨后利用放電等離子體燒結法將該粉末制備成稀土鉬金屬陶瓷材料，利用SEM、DTA、電子發(fā)射性能測試等方法對樣品次級電子發(fā)射性能進行研究。結果表明：稀土氧化物均勻摻雜和組織的細化有利于材料發(fā)射性能提高，但不能降低其激活溫度；經(jīng)過高溫氫氣處理，樣品的真空激活溫度大幅降低，發(fā)射系數(shù)提高；稀土氧化物易吸收水分和氣體的特性導致后續(xù)真空激活過程中陰極表層鉬氧化，而高溫氫氣處理消除了樣品中多余的水分和氣體，保持了樣品中金屬與氧化物的相間分布狀態(tài)，這是樣品在活化前后發(fā)射性能發(fā)生變化的主要原因。
關鍵字: 稀土；鉬；次級發(fā)射；燒結
composite REO-Mo materials
（The Key Laboratory of Advanced Function Materials, Ministry of Education,
School of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China）
Abstract: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.
Key words: rare earth; molybdenum; secondary electron emission; sintering
