| 摘要 |
<p>1469554 Thermionic cathodes BBC BROWN BOVERI & CO Ltd 8 July 1974 [9 July 1973] 30098/74 Heading H1D A thermionic cathode comprises a support of refractory metal, active La oxide dispersed within the metal and a reducing agent including C, e.g. the carbide of the metal, which reacts with the oxide in operation thereby forming a monatomic La layer on the emitting surface W or Mo and La 2 O 3 powders are annealed at 800‹ C. and pressed at 1600‹ C. A sheet formed in this manner is carburized in a benzene-H 2 mixture. During heating grain growth is inhibited by the addition of K, Al and Si compounds. The powders are preferably 0À5- 1À0Á. The support may be wire and may be made by extrusion or rolling. The cathodes are used in thermionic valves and metal vapour lamps.</p> |
