冷冻干燥法制取扩散阴极含钪活性物质

Preparation of Scandate Active Substance for Dispenser Cathode Using Freeze-Drying Method

借助液相合成法中的冷冻干燥法,制备出了高发射扩散阴极所需的含钪多元金属氧化物活性物质,其中Ba与Sc的原子比接近2∶1。应用该活性物质的浸渍阴极,取得了超过500 A/cm;的二极管脉冲发射电流密度和218.5 A/cm;的电子枪脉冲发射电流密度。在二极管直流测试条件(950°C,10 A/cm;)下,阴极的寿命测试进行了10500 h后仍未出现发射电流下降的现象;而在电子枪中的大工作比(5%)脉冲测试条件下,阴极在工作了2010 h后仍维持了超过50 A/cm;的较大发射电流密度。冷冻干燥法有效解决了传统固相合成方法在机械式破碎、研磨和混合等工序中存在的原料混合不可控、成分分布不均匀等问题,能够缩短工艺流程、节约工艺设备,有着良好的生产推广价值。

A polymetallic oxide active substance containing scandia for high-emission dispenser cathode, whose atomic ratio of Ba to Sc is about 2∶1, is prepared via a liquid phase synthesis way namely freeze-drying method. The scandate cathodes impregnated with this high emission substance have a pulse emission current density of more than 500 A/cm;under close-spaced diode configuration and218.5 A/cm;in electron gun. Under the DC diode experimental configuration(950℃, 10 A/cm;), the cathodes emission lifetime test has endured for 10500 h with no emission current drop;while in the electron gun with a pulse drive of heavy-duty cycle(5%), the cathode maintains a highcurrent density of more than 50 A/cm;after having worked for 2010 h. The freeze-drying method effectively solves the problems of ingredients mixture uncontrollability and composition distribution inhomogeneity in the mechanical crushing, grinding and mixing procedures of conventional solid-phase synthesis routine, and can shorten the synthesis routine as well as economize the process equipment, which assigns it good value for popularizing of practical production.