旋锻法制备高掺杂ThO_2纳米颗粒的W热阴极材料的结构与性能

Characteristics and Microstructure of High Doping Nanocomposite W-ThO_2 Thermionic Cathode Material by Swaging Method

采用热旋锻工艺制备了纳米复合W-4.5%ThO2阴极材料,为了对其抗烧蚀性能进行研究,在氩弧焊机(GTA)上与商用W-2%ThO2和W-4.5%ThO2电极进行了比较试验。结果表明,这种新型电极的密度接近于全致密,其组织结构与目前工艺生产的商用电极完全不同,粒径小于200 nm的ThO2颗粒弥散分布于钨基体晶粒内。纳米复合W-4.5%ThO2阴极材料的起弧性能是3种测试电极中最好的,抗烧蚀性能得到明显改善,说明电极的性能主要受ThO2含量和粒度的支配。

By hot swaging, the nanocomposite W-4.5%ThO2 cathode was fabricated. A comparative study on the anti-erosion ability for a conventional W-2%ThO2, W-4.5%ThO2 cathode and a nanocomposite W-4.5%ThO2 cathode has been made by using gas-tungsten arc (GTA) welding. The results indicated that the relative density of the nanocomposite material is near full. The microstructure of the nanocomposite cathode is quite different from that of conventional thoriated tungsten cathodes. Most of the thoria particles in the nanocomposite are less than 200 nm in diameter, and situated on the tungsten grain boundaries. The arc starting characteristic of the nanocomposite W-4.5%ThO2 electrode is the best among the three cathodes. The cathode tip shape after arc burning was obseved. The results show that the anti-erosion ability of the nanocomposite W-4.5%ThO2 cathode had been obviously improved, which indicated that the cathode characteristics depend mainly on the content and partcle size of thoria.