| 摘要 |
1,175,486. Cathode materials and processing. SIEMENS A.G. 21 Feb., 1968 [22 Feb., 1967; 27 Oct., 1967], No. 8338/68. Heading H1D. In a dispenser cathode in which a moisture insensitive alkaline earth metal carbonate charge is covered by a porous tungsten plate, both the inner and outer surfaces of the tungsten plate are covered with a layer of a metal of the platinum group or of rhenium. The metal coating may be of osmium, formed by the reduction of OsO 4 , which does not react with the Co 2 gas liberated during the charge decomposition. Further, the metal layer may be chosen such that, during operation, the escape energy at the surface in combination with barium is almost equal to that of barium with tungsten-such an arrangement will give emission which is not effected by any damage to the plate surfaces that may occur. Suitable metals are platinum, formed by reduction of, for example, PtC1 4 , or preferably rhenium, which, since the layer may be formed by deposition on to the surface, avoids the formation of any poisonous residues in the tungsten block. |
