【摘要】 采用粉末冶金方法制备了La2O3,Y2O3 Mo次级发射材料,测试了各种材料的次级发射系数。结果表明在钼中加入稀土氧化物可以具有很好的次级发射性能。经过激活处理后,材料的最大次级发射系数均高于2.0,达到了材料使用要求的发射水平。应用扫描电镜(SEM)和光电能谱仪(XPS)研究了稀土元素在烧结体断口和发射前后在试样表面的分布情况。分析结果表明稀土元素易于在晶界处偏聚,且发射后试样表面稀土元素的相对浓度明显高于发射前的浓度。更多还原

【Abstract】 The molybdenum cathode material doped with La2O3,Y2O3 was made by the powder metallurgy method. The secondary emission coefficients of various kinds of cathode materials were tested. The experimental results show that Mo cathodes doped with La2O3,Y2O3 have good secondary emission properties. When the cathodes are activated, the maximal secondary emission coefficients of these cathodes are higher than 20 and can meet the practical requirement. The distribution of the rare earth in the body and at the surface of the Ln2O3Mo cathode material before and after emission was studied using scanning electronic microscopy (SEM) and XRay photoelectron spectoscopy (XPS). The analysis results show that the rare earth is easy to gather at grain boundaries and the relevant concentration of rare earth on the surface after emission is obviously greater than that before emission.更多还原