用于浸渍阴极的钨海绵基体的净化

Purificationand Cleaning of Spongy Tungsten Disc Used As Impregnated Dispenser-Cathode in Vacuum

微波真空电子器件广泛应用于卫星通信及未来军事前沿的高功率微波武器等方面,这些器件需要电流发射稳定、蒸发小、寿命长的浸渍阴极,阴极性能好坏将直接影响微波器件的寿命及输出性能,这对浸渍阴极钨海绵基体制备工艺提出了很高要求。本文首先分析研究了传统净化工艺制备的阴极钨海绵基体,发现化学去铜过程中会有一些杂质沉淀在阴极钨海绵基体上;另外,传统净化方法去铜时间很长,一般在几十至几百小时;同时化学去铜也会造成环境污染。为了克服传统净化工艺的缺点,利用金属材料饱和蒸汽压的物理特性,将阴极钨铜合金基体直接放入真空室内的加热坩埚中,通过高(中)频加热线圈对坩埚进行局部加热,从而使含有铜的阴极钨铜合金基体被加热,使其中的铜迅速蒸发而沉积到冷凝器上并形成铜钟乳。实验结果表明直接进行真空高温去铜工艺技术具有去铜彻底、基体表面没有残留污渍、时间短、对高温炉无污染、对环境无污染等优点。对实验结果进行了理论分析计算,计算结果与实验结果相符合。

The highly purespongy tungstendisc,widely used as impregnated dispenser-cathode in microwave vacuum electronic devices,was fabricated by high（ mid） frequency induction heating of W-Cu alloy in the vacuum reactor with a water-cooled condenser. The impact of heating temperature and time on porosity and purity of the spongy W-disc was investigated. The results show that the highly clean and pure spongy W-disc can be fabricated by induction heating. For example,heated at 1900 K for 60 min at 10-3 Pa,little residue Cu exist in the spongy Wdisc; and Cu formed a stalactiteon the condenser. The novel induction heating technique outperforms the conventional wet chemical method in many ways,including the environmental friendliness,much shorter time,higher purity. The surface segregation and vacuum evaporation of Cu from W-Cu alloy was theoretically analyzed. The calculated and measured results were in good agreement.