| 摘要 |
1,038,775. Cathodes. WESTERN ELECTRIC CO. Inc. April 25, 1963 [May 21, 1962], No. 16266/63. Heading H1D. A sintered matrix cathode comprises a nickel mix 11, consisting essentially of nickel and an activator material, moulded with an emitting mix 12 including nickel and at least one alkaline earth compound, and sintered, and a film 13 ofone or more of the metals nickel, molybdenum, tungsten and cobalt deposited on the emissive surface. The film 13 permits conversion of the alkaline earth compound to the corresponding oxide prior to assembly of the cathode within an electron tube. In a preferred method, the nickel mix 11 comprises nickel powder mixed with 1 to 5 % by weight of an activator, e.g. compounds of zirconium or magnesium, or a nickel-zirconium alloy powder, and the emitting mix 12 comprises 10 to 30% by weight of a single, double or triple alkaline earth carbonate, 0 to 5% of an activator, and the remainder carbonyl-derived nickel powder. The mixes are moulded under a pressure of 10 to 100 tons before heating in dry nitrogen to 600‹ C. A nickel film 13, 500 to 2000 Š thick, is then deposited by vapour coating or cathodic sputtering over the free surface of the emitting mix. Finally, the carbonates are converted to oxides by heating in dry hydrogen to 1000‹ C., after which the cathode may be stored or assembled in a thermionic tube. The cathode may have a concave emissive surface for use in convergence type guns. A specific example is given. |
