GB1322757A - Getter devices and processes - Google Patents

Abstract

1322757 Getter device SAES GETTERS SpA 12 June 1970 [14 June 1969] 28647/70 Heading H1D A getter device for insertion in an electron tube (e.g. a c.r.t.) comprises a getter material, first and second gas releasing materials disposed and arranged so as to be capable of actuation successively to provide at successive stages in a gettering process first and second releases of gas, each gas having the property of improving the sorption properties of the getter material. The getter material may be an alkali or alkaline earth metals, e.g. Ca, Mg, Sr and Ba, the latter preferred. The getter metal may be alone but is preferably a getter alloy including one or more less reactive metals, less reactive to air, preferably Ba-Al in wt. ratio 10 : 5 to 10 : 20 and binary alloys containing 50 to 56% Ba, balance Al. Getter metals and alloys alone produce endothermic getter devices operable by induction heating, but is preferably exothermic as when mixed with Ni wherein heat for vaporization is produced exothermically between the Ni and the alloy. The inductively heatable ring can be of variety of continuous shapes. Suitable gases include carbon-monoxide, carbon dioxide, oxygen, and preferably hydrogen and/or nitrogen. The two gases may be the same, e.g. nitrogen. Gas releasing materials include barium carbonate, the metallic hydrides, barium nitride, barium hydride, titanium hydride, phosphorous nitride and preferably iron nitride (Fe 4 N). Respective wt. ratios of the getter material and gas releasing materials and gas producing pressures are given. Fig. 1 includes ring 21, pressed particulate mixture 22 of (a) Ba-Al aloy and Ni, and (b) Fe 3 N, disc shield 23 of heat conductive material, holding gas releasing material 25, heat insulating base 29 attached by tabs 28, mounting tab 30, and depressions 31 to reduce heat transfer. Fig. 3 and 4 (not shown) include modified holder (41), Figs. 5 and 6 (not shown) include annular channel (51) and cylindrical holder (55), Fig. 7 (not shown) includes a mixture (62) of gas releasing material and evaporable material, support member (63) attached by spot welding and holder (67) containing gas releasing material, Fig. 8 (not shown) includes spring biased strip (72) attached to the electron gun, inductive heating beng via H.F. operated coil (74). Fig. 9 (not shown) includes support (82) holding getter device (50), with holder (55) for the further gas releasing material. Figs. 10, 11 (not shown) illustrate comparative gas releasing characteristics and Fig. 12 (not shown) the sorbtion characteristic, discussed in relation to specific examples of operational procedures and parameters. Reference is made to Specification 496,856.