US2449786A - Getter - Google Patents

Description

Sept. ,21, 1948.` l G. H. LQcKwooD ETAI. 2,449-785 GETTER Filed March 5....1943.

BY Mm ATTORNEY Patented Sept. 21, 1948 STATES PATENT OFFICE Corporation, East Pittsburgh, Pa, a crporation of Pennsylvania Application March 5, 1943, Sel No. 478,116

s claim. (ci. 31e-25) This invention relates to incandescent electric lamps and similar evacuated or hermetlcally sealed devices, and more particularly, to a getter suitable for the purpose.

The primary object of our invention, generally considered, is the use of a. material having a strong afilnity for carbon monoxide and oxygen, and forming non-volatile porous compounds therewith, for cleaning-up undesired residual gases in hermetically sealed devices such as in-A candescent electric lamps and the like.

Another object of our invention is to employ a getter in incandescent electric lamps and similar devices which avoids filament embrittlement and the formation of an impervious coating, whereby it is completely available for clean-up purposes.

A further object of our invention is the employment .of a getter consisting essentially of powdered free metallic zirconium, thorium, cerlum or the like, particularly adapted for incandescent electric lamps and similar evacuated devices using nlekel-plated iron and nickel leads, which is especially adapted for cleaning-up such undesired residual gases as carbon monoxide and oxygen, thereby improving the operation and maintenance of such devices. Carbon monoxide is especially undesirable with nickel and iron because of the formation of volatile carbonyl compounds therewith.

A still further object of our invention is `the employment of a getter, such as described in the preceding paragraph, in combination with iinelydivided or powdered aluminum or other similar material which serves the multiple purpose as a binder for the getter metal powder, for making the mixture more visible when applied to an interior lead of the device, and for providing additional getter action.

Other objects and advantages of the invention will become apparent as the description proceeds.

Referring to the drawing:

Figure 1 is an axial sectional view, with parts in elevation, of a lamp embodying our invention.

Figure 2 is a transverse sectional view on the line II-lI of Figure 1.

With the increasing shortage of such strategic materials as copper and nickel due to war conditions, manufacturers have found it expedient to Y resort to the use of nickel-plated iron leads for incandescent electric lamps and similar evacuated or inert gas-filled devices. With such leads as well as nickel leads, particularly due to the desirability of annealing in order to clean and soften them, which annealing also usually took place in a carbon-monoxide-containing atmosphere, it has been found that getters such as previously used are unsatisfactory due to an embrittling action on the -tllament of the residual carbon-monoxide which was not entirely cleaned up.

In searching for an eiective clean-up agent for carbon monoxide, as such gas is particularly bad because of its cycle with nickel and iron due to its formation of vaporizable carbonyl compounds with such materials, it was found that a getter consisting essentially of at least one of the powdered metals such as zirconium, thorium and cerium, having a strong affinity for carbon monoxide and oxygen, forming non-'volatile but porous compounds therewith, in combination with fine degreased aluminum akes, that is, not including other ingredients except minor impurities, is particularly suitable when applied, as by means of a. harmless vehicle such as amyl acetate, by painting on lead and/or support wires in miniature and large incandescentillament lamps.

The rare metals mentioned are considered the most active ingredients for the desired clean-up purpose, but the flake aluminum ls desirably employed therewith to perform the multiple function as an auxiliary getter material, a binder for the other metal powder, and as a visibility-increasing agent. It will be understood that zirconium metal powder, for example, is dark grey in color and, therefore, would not be very visible if it alone were mixed with amyl acetate and painted on a. lead-in conductor or other non-incandescing portion. With a suitable minor proportion of aluminum, however, it shows up clearly in the same way in which aluminum paint would and is more firmly held in place by such auxiliary material.

The proportions of the lngredlentswhich have been found suitable for the purpose are as follows:

Zirconium metal powder, 325 mesh grams 18 Degreased aluminum ake, 400 mesh do 4 Amy] acetate cc-.. 40

The above formula is now in use in the factory production of lamps and has given good results.

In the drawing, the reference character I0 denotes an incandescent electric lamp comprising an envelope Ii based as indicated at I2, and enclosing a are tube I3.` From the tube i3l extends lead-in conductors Il and I5 to an incandescible lament I6, secured to an arbor i1 by one or more support wires Il;

In the .present embodiment, the lead wires Il and I5 and the supporting wire, or wires, Il are shown coated with a paint I9 comprising thel desired getter mixture in a vehicle such as amyl acetate. Although in the present embodiment, all of these parts numbered Il, I 5 and Il, are shown with the getter material thereon, it will be understood that such material may if desired be applic to only some of these parts.

From the foregoing disclosure it will be seen that we have developed an improved getter'particularly adapted for use on nickel-plated iron and nickel leads and supports in incandescent electric lamps, whether gas-lled or vacuum type. It consists essentially of a major proportion of material such as powdered zirconium, thorium, cerlum, that is, at least one oi' said 'powdered metals or other similar material having a strong ainity for carbon monoxide and oxygen, forming non-volatile and porous compounds therewith and which has no embrittling eect on the illament, while at the same time being sufllciently active at relatively low temperatures to operate when applied to a lead or support in the envelope, as distinguished from the application to an incandescible filament and a minor proportion of ilnely divided aluminum.

Although preferred embodiments of our invention have been described. it will be understood that modiiications may be made within the spirit and scope of the appended claims. It will,`how ever, be understood that there is no intention to include unmentioned ingredients other than minor impurities.

We claim:

1. A getter for incandescent velectric lamps consisting essentially of a major proportion of at least one free powdered metal selected from the group consisting of zirconium, thorium, and cerium, admixed with a minor proportion of degreased aluminum ilake to act as a binding and auxiliary clean-up agent.

2. A getter for incandescent electric lamps consisting essentially of a major proportion of zirconium metal powder, admixed with a minor proportion of degreasedv aluminum flake to act as a bindingagent and auxiliary clean-up agent. 3. A getter composed of ingredients admixed vin about the following proportions: zirconium metal powder, 325 mesh, 18 grams; aluminum flake-400 mesh, 4 grams; and amyl acetate, cc. f

4. A getter for incandescent electric lamps consisting essentially of a major proportion of thorium metal powder, admixed with a minor proportion of degreased aluminum iiake to act as a binding and auxiliary clean-up agent.

5. A getter for incandescent electric lamps 4 comprising essentially a major proportion o1' cerium metal powder, admixed with a minor proportion of degreased aluminum ake to act as a binding and auxiliary clean-up agent.

6. A getter for residual gases in hermetically sealed envelopes comprising a coating on an ele.

ment therein which inservice becomes hot without incandescing, consisting o! ingredients admixed in about the following proportions: zirconium metal powder, 325 mesh, 18 grams; aluminum ilake, 400 mesh, 4 grams; and amyl acetate, 40 cc.

7. A getter for incandescent electric lamps comprising a coating on an interior lead portion thereof consisting essentially of a major proportionl of at least one powdered free metal selected from the group consisting of zirconium, thorium and cerlum admixed with a minor proportion of degreased aluminum iiake. l

8. A getter for residual gases in hermetically sealed envelopes comprising a coating, on an element therein which in service becomes hot without incandescing, consisting'essentially o! a major proportion of at least one free powdered metal selected from'the group consisting oi zirconium, thorium and cerium. admixed with a minor proportion of finely-divided aluminum.

GEORGE H. LOCKWOOD. DONALD F. WAY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 286,916 Fitzgerald v.. Oct. 16, 1883 1,323,836 Coolidge Dec. 2, 1919 1,560,981 De Graaff Nov. 10, 1925 1,590,352 Eglin June 29, 1926 1,626,235 Gustin Apr. 26, 1927 1,653,367 Marden Dec. 20, 1927 1,691,177- Balke Nov. 13, 1928 1,859,029 De Br et al May 17, 1932 1,859,043 Maartens May 17, 1932 1,864,084 Miller June 21, 1932 1,894,948 Espe et al Jan. 24, 1933 1,922,162 King s Aug. 15, 1933 1,967,575 Hunter, Jr. July 24, 1934 2,117,735 Lester May 17, 1938 2,295,694 Slack et al. Sept. 15, 1942 2,341,483. Stephen A.' Feb. 8, 1944 A FOREIGN PATENTS Number v CountryA Date 107,314 Australia May 11, 1939 482,022, Great Britain Mar. 22, 1938

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