| 摘要 |
1,240,778. Discharge lamps; electrode materials and processing. PATENT-TREU. HAND-GES F R ELEKTRISCHE G.m.b.H. 12 Sept., 1969 [12 Sept., 1968], No. 45195/69. Heading H1D. [Also in Division C7] In a high pressure compact arc lamp, having an almost spherical envelope 1 with two main electrodes 5, 6 spaced, about its centre, by a distance which is small relative to the diameter of the bulb, the main electrodes 5, 6 comprise sintered bodies composed solely of from 20- 90% by weight tantalum carbide and from 80- 10% by weight of one or more of the metals tungsten, rhenium, molybdenum and tantalum. The electrodes 5, 6 as shown, have frustoconical ends and may be mounted on forged and ground tungsten core bars 3, 4 which have tungsten wire coils 7, 8 for supporting a starting emitter material, e.g. thorium, disposed adjacent the electrode ends 5, 6, and one of the core bars may contain an additional gettering coil 9 of tantalum wire. An electrode containing 60% tantalum carbide and 40% tungsten may be formed by mixing powders of these materials with 2% camphor dissolved in diethyl ether and stirring until the solvent has evaporated, pressing cylindrical sintered bodies from a mould and the blanks are annealed for 10 min. at 1500 C. in a forming gas. After forming the apex of the cone the sintered bodies are shrinkfitted on to core bars. The filling of the lamp may comprise 35 Torr of argon as starting gas and mercury to give an operating pressure of from 10 to 100 atmospheres. The lamp filling may additionally or alternatively contain a metal halide, or the lamp may be of the compact arc xenon type for A.C. operation. |
