US1026392A - Incandescent-lamp filament. - Google Patents

Description

. No Drawing.

CHARLES A. Hansen, or SGHENECTADY, NEW YORK,

ASSIGNOR TO GENERAL ELEG- TRIO COMPANY, A CORPORATION OF NEW YOBIL,

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Specification of Letters Patent.

Application filed April 8, 1908. Serial No. 425,814. 1

Patented May 14, 1912.

To all whom it may concern:

Be it known that I, CHARLns A. HANSEN, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have lnvented certain new and useful Improvements in Incandescent-Lamp Filaments, of which the following is a specifica tion.

In the production of incandescentflamp filaments consisting of tungsten, titanium, zirconium, and similar refractory 1n tals and compounds, it has been customary. to use some sort of a binding material by the aid of which the powdered refractory metal or material could be shaped into threads or wires. Some inventors have made use of carbonaceous binders, such as tragaca'nth, sugar solutions, glucose, and starch paste, but the removal of the carbonaceous residue left by such binders has, in general, proved ditficult and expensive.

According to my present invention, refractory powdered material, such as tungsten, is shaped into threads or wires by means of a binder which on a further treatment breaks up or decomposes, and furthermore is of such a nature and breaks up in such a way that the residue is notinjurious to the filament and need not be removed therefrom. In fact, the particular binder hereinafter mentioned as a specific embodiment of my invention yields a residue of such low conductivity that the completed filament has a high specific resistance and can be used on relatively high voltages.

The binders contemplated by my present invention include those sticky metal oxalates which when highly heated calcine to a stable and refractory oxid of the metal. Zirconium oxalate is typical of this class. Its use in the production of filaments consisting essentially of tungsten is hereinafter described in detail, and will serve to give personsskilled in the art a working knowledge of my invention.

Zirconium oxalate can be prepared by precipitation of hot zirconium nitrate solution with ammonium oxalate. The precipitate is gelatinous in character, resembling starch paste in consistency, and has a smooth, even texture. By using ordinary care durlng manufacture, the zirconium oxalate can be made exceedingly pure.

In making up the mixture of powdered tungsten and zirconium oxalateyl may use ust suflicient oxalate to give tenacity to the mass, or I may use a much greater-quantity with the idea of thereby obtaining a filament of articularly high specific resistance.

The p 'astic mass above described can be squirted into wires or threads in an ordinary manner and should then be' dried and finally heated to a high temperature to calcine the oxalate and convert it into zirconium oxid. This high temperature treatment may be effected by passing current through the filament while supported in a vacuum or suitable gas, theheat treatment being carried far enough to completely sinter and shrink the filaments into a coherent and homogeneous body of tungsten uniformly mixed with zirconium oxid.

As an alternative method of heating, I may make use of the vacuum furnace shown in United States Patent to March 21, 1905, though I prefer to use in place of the graphite heater there shown a heater consisting entirely of tungsten. If desired, the heat treatment in the furnace may be stopped somewhat short of complete shrinkage, thus ermitting completion and shaping of the laments in treating bottles or in the lamp bulbs themselves.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The. method of filament manufacture which consists in forming threads consisting of a mixture of powdered refractory conductive material with a binder composed essentially of a gelatinous oxalate of a metal having a stable refractory oxid, and subsequently heating said threads to convert the oxalate into the oxid and to consolidate the materials into a coherent conductor.

2. The method of filament manufacture which consists in forming threads consisting of refractory metal powder held together by a binder composed essentially of a gelatinous oxalate decom o'sable to yield a refractory oxid, and heating said threads-in an inert environment to convert the oxalate into oxid and to consolidate and sinter the refractory metal.

Arsen #785,535,

3. The method of filament manufacture which consists in forming threads consisting of refractory powder held together by a binder composed essentially of zirconium oxalate, and. subsequently treating these threads to convert them into homogeneous conductors containing zirconium oxid mixed essentially of a metal oxalate decomposable to produce a stable refractory oxid.

6. A squirting mixture for lamp filaments consisting of powdered refractory material and a binder composed essentially of zirco- V nium oxalate.

7. A squirting mixture for lamp filaments consisting of tungsten powder and a binder composed essentially of zirconium oxalate.

8. A squirting mlxture for lamp filaments consisting of tungsten powder and a binder composed essentially of an oxalate decomposable to yield a stable refractory oxid.

In witness whereof I have hereunto set my hand this 7th day of April, 1908.

CHARLES A. HANSEN.

Witnesses:

HELEN Onrono, BENJAMIN B. HULL.