| 摘要 |
734,209. Cathode materials and processing. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Nov. 26, 1952 [Nov. 29, 1951], No. 29949/52. Drawings to Specification. Class 39 (1). In a cathode having an emitting surface of porous refractory metal, and an internal supply of emissive material, the latter consists of a mixture of one or more alkaline earth oxides with one or more of the oxides of silicon, aluminium, beryllium, boron or thorium, the mixture being fused before introducing into the cathode body. These materials yield free alkaline earth metal upon reaction with the refractory metal, with little or no liberation of gas. Examples given are (1) a pastille of barium silicate Ba 4 Si0 6 (4BaO.Si0 2 ) surrounded by a charge of powdered tungsten, the whole being compressed and sintered at 12500‹ C.; (2) a supply of alkaline earth thoriate or beryllate with an excess of alkaline earth oxide, behind a porous tungsten wall; (3) barium aluminate formed by melting 70 per cent BaO and 30 per cent Al 2 O 3 at 3000‹ C., followed by mixing 10 per cent of the aluminate with 90 per cent tungsten powder, pressing and sintering at 1370‹ C. for 20 minutes. |
