對鑭-碳化鎢陰極發(fā)射大和抗油蒸汽中毒的探討
STUDY ON EMISSION PROPERTIES OF La-WC CATHODE AND ITS RESISTANCE TO POISONING OF OIL VAPOUR
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摘要: 本文提出了解釋鑭-碳化鎢(La-WC)陰極發(fā)射大和抗油蒸汽中毒能力強(qiáng)的一些設(shè)想,并通過實(shí)驗(yàn),驗(yàn)證了所提出的設(shè)想。在La-WC陰極的工作溫度范圍內(nèi),La和 WC發(fā)生化學(xué)反應(yīng),生成La2C3。La2C3也是一種良好的發(fā)射材料,它具有與鑭相近的逸出功。La2C3能與鑭形成共熔體,對鎢基底浸潤良好,易形成較好的發(fā)射層,而使發(fā)射顯著增大。La-WC陰極抗油蒸汽中毒是由于污染的碳與共熔體中的鑭形成La2C3,而La2C3也是良好的發(fā)射物質(zhì)的緣故。
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關(guān)鍵詞:
Abstract: In this paper, an assupmtion to explain emission properties of the La-WC cathode and its resistance to poisoning of oil vapour is presented and was demonstrated by experiments. In the operating temperature range of the La-WC cathode, lanthanum would react chemically with tungsten carbide and form La2C3. La2C3 is a kind of good emissive material with a work function approximate to lanthanum's and can also combine with lanthanum into an eutectic. The eutectic is easy to wet the tungsten matrix and migrate over its surface to form a thin emission film. As a result, the cathode emission is greatly increased. In addition, the La-Wc cathode has capability to resist poisoning of oil vapour is for the reason that the carbon from the oil vapour reacts with the lanthanum in the eutectie and forms La2C3, which is also a good emissive material. -
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