GB244116A - Improvements in or relating to methods of making sag resisting bodies of tungsten - Google Patents

Abstract

244,116. British Thomson-Houston Co., Ltd., (Assignees of Dushman, S., and Kober, P. A.). Dec. 8, 1924, [Convention date]. Filaments.-Tungsten filaments &c. are heated to the temperature of rapid grain growth for a time sufficient to cause them to become non- sagging when used in gas-filled lamps, the treatment being effected by laying them in a refractory metal trough which is heated to incandescence by the passage of an electric current therethrough. Coiled filaments may be placed in a tungsten boat or tube 11, Fig. 1, provided with a cover 20 and mounted on conductors 12, whereby a heating-current may be passed through it from a transformer 18. The boat is covered by a bell 23, supplied with the requisite inert atmosphere. The wire used may be produced by the process described in Specification 155,851. The process is stated to be applicable to the production of tungsten articles generally in which a large crystal structure is required. According to the Specification as open to inspection under Sect. 91 (3) (a), a coiled filament 28, Fig. 5 (Cancelled), is passed between electrodes 29, 30, between which short lengths of filament are heated and cooled before the succeeding length is treated. The mercury constituting these electrodes is cooled by water-pipes 32. Bulbs are illustrated containing long filaments produced bv the above-described methods and supported only at the ends. Fig. 10 (Cancelled) shows a bulb having a helical filament of more than ten times the diameter of the wire, and supported only at the ends. In connection with the filament shown in Fig. 11 (Cancelled) in a bulb as commonly used in vehicle head-lights, the usual intermediate support is omitted. This subject-matter does not appear in the Specification as accepted.