| 摘要 |
The method for mfg. a cathode comprises (a) heating a cathode cap containing Ni, 0.03-0.1 wt.% Si and 0.03-0.1 wt.% Mg in the vacuum furnace at 700-900 deg.C, (b) carburizing the surface of the cathode cap with a carburizing gas to form 10-80 m carburized layer, (c) ultrasonic cleaning the cathode cap, (d) fixing the cap to the sleeve, (e) spray-coating an alkali earth metal on the cap to form a thermionic emission layer, and (f) activating the layer. The layer comprises a ternary carbonate of Ba, Sr and Ca, and 0.1-20 wt.% rare earth metal oxide.
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