钪钨基压制型阴极的制备及性能研究

Preparation and Emission Property of Scandia Doped Tungsten Pressed Cathode

将活性发射盐与氧化钪掺杂钨粉采用不同混合的方法结合,结合氢气气氛下的高温烧结法制备了氧化钪掺杂钨基扩散阴极。实验结果表明元素混合的均匀性对阴极的发射有着重要的影响。采用高能球磨法混合的粉末,元素分布均匀且颗粒细小,高温烧结过程中有利于发射盐与基体元素钨之间反应充分,形成有利于发射的活性物质。该种方法制备的阴极,发射性能为手工研磨混合的8倍,且为覆Os钡钨阴极的4倍。在激活过程中,活性元素Ba、Sc和O从阴极内部向表面扩散,在表面形成均匀分布的含Ba、Sc和O的活性层,促进了阴极的发射。

Scandia doped tungsten pressed cathodes were prepared, including mixing scandium oxide and barium-calcium aluminates with tungsten by different powder mixing methods combined with high temperature sintering under the protection of hydrogen. Experimental results show that mixing uniformity plays important roles in the cathode emission. The powders prepared by ball-milling have small particle size and uniform distribution of different elements. This kind of powder is favorable for the chemical reaction between emission salt and tungsten totake place fully to form active substance which could improve the emission property. The emission current density of the cathode prepared with ball-milling powders is about eight times higher than that prepared with hand mixing, at the same time, four times higher than M-type cathode.During the activation of cathode, the surface active layer containing Ba, Sc and O is established due to the simultaneous diffusion of Ba, Sc and O, leading to the improvement of emission property.