US908930A

US908930A - Method of decarbonizing filaments for incandescent lamps.

Info

Publication number: US908930A
Application number: US34134906A
Authority: US
Inventors: Hermann Zerning
Original assignee: Individual
Current assignee: Individual
Priority date: 1906-10-30
Filing date: 1906-10-30
Publication date: 1909-01-05
Anticipated expiration: 1926-01-05

Description

IATEs Perm OFFIGE.

. zranmg GERMANY. I ammo]: or n fifmonnmo manure Ion magnu Lm To all whom it. may Be it known that I, HnRMANN'ZEnNmo, a subject of the King of Prussia, and resident of Halensee, near Berlin, in the Kingdom of Prussia, German Empire, have invented new and'useful Improvements in Methods of Decarbonizin Filaments for Incandescent Lam s, of which the following is a full, clear, an exact description.

In the manufacture of the filamentsconsisting of metallic compounds for incandescent lamps, it is necessar to obtain the finished filaments as clear f iom carbon as ossible, because a small quantity of carbon influences the resistance or stren th and usefulness of the filaments considerably. Most methods hitherto contrived for this purpose cannot be carried out on a large scale without great dilficulty and scarcely permit the perfect removal of the carbon unless means are used which simultaneously attack the metal of which the filament consists.

My'present invention is intended to enable the filaments to be completely decarbonized on a large scale without the metal of the filament suffering.

The invention consists in decarbonizing the-filament by means of nitrogen gas or nitrogenous gases, roduced byheating phospham (PN H) with or without an addition of phosphorus in a vacuum.

The nitrogen contained in phospham passes off at a relatively low temperature, and forms, in a free state,.with the carbon, cyanogen or the like, or oxidized compounds of the same. The phosphorus, 'which becomes free simultaneously. is able to combine with the oxygen still present, or to exert its reducing action on the metal oxid impurities, which may perhaps still be present in the filament. The phosphorus added is of special importance when it may be assumed that the. filament contains a considerable quantity of oxygenous impurities.

In carrying out the invention a small percentage of phospham to which some phosphorus may be added is mixed withthe metal powder from which the paste used for squirting the filaments of incandescent lamps is made and then a paste is very carefully prepared. The amount of phospham depends on the nature of the binding agent used .and is larger according as the binding agent contains more carbon. The

v Y -Bpeeiflcgtion of Letters Patent.

Appjlgefion flied; emb ao,'19os. Serial No. 841,340,

Patented Jan. 5, 1909;

proportion of phospham in the finished paste amounts to 4 per cent., for instance, when tar is employed as the binding agent. The action of the phospham takes place immediately, when the filament is made incandescent in a vacuum, as it then becomes absolutely free from carbon without its strength being impaired in any manner.

Another method for carrying out the process is designed to liberate the nitrogen contained in the phospham and to allow it to act exteriorly on the filament. In this case the filaments are placed in a suitable furnace, in which a vacuum is produced. The furnace is then heated up to about 130, in order to remove the water and the products of decomposition evolved at that temperature, whereupon the taps of the pum are closed and the furnace is now heat slowly up to 800 to 1000 C. The phospham is decomposed and the nascent gaseous materials will have a pressure of some millimeters of mercury according to the quantity of phospham employed. amount of phospham depends on the binding agent used 1n manufacturing the paste for the filaments. If the binding agent is -very carbonaceous, then a correspondingly larger quantity of phospham must be employed and the heating correspondingly prolonged. Filaments treated according to this process are perfectly free from carbon and are firm. This heating process may also be carried out with the assistance of the electric current in any vessel in which a vacuum can be produced, or in the bulb of an incandescent lamp. When the filaments are thus treated, said filaments can bedusted over or otherwise coated with phospham. For example, finely powdered .phospham can be mixed with a paste which is applied to the filament with a brush. -When the filament so coated is rendered incandescent by the electric current nitrogen is also separated.

If the filament is to be decarbonized after it has been inserted in the bulb of an incandescent lam the following method is preferably emp oyed:-Powdered phospham is mixed with alcohol and then applied tothe filaments before it is melted down. Instead of this, the phospham paste can be placed on the electric wires, supports etc. exhausting the air out of the bulb by means of a pump, the tap between the lamp and the air-pump is closed and the lamp is made The After in the lamp is not lessened.

- ed 'outsi current. The phospham is thus vaporized no matter where it may be situ the lamp. Finally, itmay be mentioned, that the phos ham may in this casealso be heate the lamp in a' space, which may be connected with the lamp. Of, course the arrangement must be such that the vacuum Having thus described my invention, what I claim as new and desire to secure by Letters, Patent is 1.-The method of producing a decarbonized filament for incandescent lamps, consisting in lacing a filament in a compartment, pr

ment, and heating said filament'in said comucing a vacuum 1n said'compartwhile maintaining the vacuum:

7 2. The "method of producing-a decarbonwitnesses.

ERNING.

two subscribin HERMAN N Witnesses:

HENRY HASPER, Womnmnn Ham.

the presence of maps Mama's v v o I 7 -20. ized fi1amentfor incandescent lamps, conmyname this 30th day of August 1906, in i