GB191413076A - Improvements in and relating to the Manufacture of Tungsten. - Google Patents

Abstract

13,076. British Thomson-Houston Co., [General ELectric Co.]. May 27. Modifying chemical characters of metals.- Drawn tungsten wire which readily takes a permanent set without heating is produced by heating the wire, prepared by one or more of the methods described in Specifications 21,513/06, [Class 82, Metals and alloys], 23,499/09, [Class 82 (ii), Washing granular &c.], 8031/10, and 9877/12, [Class 82 (ii), Washing granular &c.], and after the drawing operation has been completed, in the presence of an oxidizing-agent. The wire may be treated after it has been mounted in a lamp, by passing current through it while the lamp is connected to the evacuating-pump and before the usual degree of vacuum is reached, the small amount of oxygen present having the desired effect; or the wire may be treated before mounting it in lamps. The process may be applied to wire which has been treated for the prevention of off-setting. In a modified process, the wire may be first slightly oxidized and then heated strongly in a good vacuum or in nitrogen, forming gas, or a mixture of nitrogen and hydrogen, with or without air or water vapour. Specifications 20,175/05. [Class 82, Metals and alloys], and 14,048/13, [Class 39 (ii), Electric lamps, Incandescent], also are referred to.