US1150670A - Treatment of refractory metals. - Google Patents

Description

e, GM U R-ZEHNDER.

TREATMENT OF REFRACTORY METALS.

APPLICATION FILED JAN. 5. 1915.

2 SHEETS SHEET 1.

1,150,670. Patented Aug. 17', 1915.

g z Q G. GMUR-ZEHNDER.

TREATMENT OF REFRACTORY METALS.

APPLICATION FILED JAN. 15, 1915.

Patented Aug. 17, 1915.

2 SHEETS-SHEET 2.

I I r? UNITED STATES. PATENT FFICE.

GOTTLI'EB GMtl'R-ZEHNDER, OF AARAU, SWITZERLAND.

TREATMENT OF REFRACTORY METALS.

Application filed January 15, 1915.

To all whom it may concern:

Be it known that I, GOTTLIEB GMiiR-Znnraman, a citizen of the Swiss Republic, residing at Aarau, in the Republic of Switzerland, have invented certain new and useful Improvements in Treatment of Refractory Metals, of wh ch the following is a specification.

This invention relates to the treatment of refractory metals and provides an improved process and apparatus especially but not exclusively intended for the manufacture of I metallic tungstenin a form suitable for the formation of metallic lamp filaments.

The process is based upon my discovery that if tungsten isfused to 'a perfectly liquid condition and is then very rapidly cooled it will not form a coarse crystalline grain (as is the case with a tungsten alloy containing even a minute proportion of other metals) but will be exceedingly fine in its granular structure and will be perfectly malleable and ductile.

My process, therefore, consists in fusing tungsten (usually in the form of a powder obtained from the oxid by any of the well known processes) in an electric furnace into a perfectly liquid state and in then suddenlycooling the liquid mass. The fusion and subsequent rapid cooling are preferably effected in an electric furnace of resistance type, in which the tungsten is placed in an inner receptacle heated byradiatidn from 'the inclosing walls of the resistance material I (about 3000 C.) the cold air blast is the most efficient means of rapid cooling, ordinary methods of cooling by liquids being unsuitable owing to the instant formation of badly conducting layers of vapor.

I An electric furnace embodying my invention is shown in the accompanying drawings, in which Figures 1 and 2 show a typical furnace Specification of Letters Iatent.

Patented Aug. 1'7, 1915.

Serial No. 2,478.

with electrical and mechanical connections in diagrammatic form, the furnace being illustrated in closed and open positions.

a is a tube of graphite or hard carbon or other suitable refractory material, which receives the substance (1. that it is desired to fuse.

b is the inner heating tube and c the outer inclosing tube, both of graphite or other highly refractory material possessingthe necessary conductivity.

d and e are respectively the top and bottom blocks which close both ends of the tubes 6 and 0 when the furnace is closed, the tubes being, in the construction illustrated, carried by the upper block d which can be raised or lowered to open or close the furnace.

The tubes 6 and c and blocks d and 6 may all be of the same material.

When the furnace is closed current is supplied through the leads g, g and top and bottom blocks 0Z and e to the two tubes 6 and a, which are heated by the current to any temperature desired. Since the temperature of the inner surface of the outer tube 0 is substantially the same as that of the tube 72 loss of heat by radiation from the latter is almost eliminated, external losses being practically confined to radiation from the outer surface of the outer tube. The outer tube also combines with any oxygen which may enter or remain in the furnace and protects the substance at from oxida tion/ The central tube a and its contents are soon raised by the internal radiation of heat from the inner walls of the tube 5 to practically the same temperature as that of the tube and a complete and homogeneous fusing of the highly refractory metals or the block 0? with the tubes 6 and c is raised into theposition shown in Fig. 2 by means of the rope orcord it connected to the lifting arms f and passing over pulleys to a counter-weight. The operation may be effected by the lever i forming a contact breaker or switch at 70 so that the electrical circuit is broken at this point immediately the furnace begins to open.

For rapid cooling of the substance in the central tube a a blast cold compressed air is provided through the elongated fun- Z ide the er tcrnal casing m and directed upon the tube a from both sides. The

air supply is preferably turned on automatically on opening the furnace so that the cooling action maybe made extremely rapid.

In starting the operation the tube a is filled with the material (Land inserted While thefurnace is open as in Fig. 2. On lowering'the block (Z and tubes 6 and 0, when the latter meet the lower block 6, the circuit is automatically completed and the current passes through the tubes 2') and 0 until the contents of the furnace are fused or brought into the desired condition.

What I claim and desire to secure by Letters Patent of the United States is 1. A process for producing pure malleableand ductile tungsten, consisting in fusing the metal to a perfectly fluid state and then rapidly cooling the same.

2. A process for producing pure malleable and ductile tungsten, consisting in fusing the metal to a perfectly fluid state and then rapidly cooling the same by a blast of cold air.

3. A process for producing pure malleable and ductile tungsten, consisting in fusing the metal to a perfectly fluid state by radiant heat produced electrically, and then rapidly cooling the metal.

4. A process for producing pure malleable and ductile tungsten, consisting in fusing the metal to a perfectly fluid state by radiant heat produced electrically, and then rapidly cooling the metal by a blast of cold air.

5. An electric resistance furnace for refractory materials, comprising an inner chamber formed by Walls of conducting material inclosingfthe substance under treatment and a surrounding chamber whose walls are separated from the inner chamber by an air space and also carry current and are heated to about the same temperature as the walls of the inner chamber. A

6. In an electric resistance furnace for refractory materials, two concentric vertical current conducting tubes inclosing the material under treatment, top and bottom conducting blocks between which the tubes are mounted and means for raising the tubes to open the furnace and break the electric circuit through the tubes.

7. In an electric resistance furnace for refractory materials, an inner and an outer vertical heating tube, both tubes carrying current, top and bottom conducting pieces between which the tubes make contact, and

an inner vesselcontaining the material under treatment and preventing it taking any ing walls, means for opening the furnace and exposing the contents and means for supplying a blast of cooling air on opening the furnace.

' 9. In an electric resistance furnace for refractory materials, Lwo concentric vertical current conducting, tubes inclosing the material under treatment, top and bottom conducting blocks between which the tubes are mounted, means for raising the tubes to open the furnace and break the electric cir cuit through the tubes, and means for supplying a blast of cooling air to the heated material on raising the tubes.

10. In an electric resistance furnace for refractory materials, two concentric vertical current conducting tubes inclosing the material under treatment, top and bottom conducting blocks between which the tubes are mounted, means for raising the tubes to open the furnace and break the electric circuit through the tubes, and air blast funnels directed upon the heated material.

11. In an electric resistance furnace for refractory materials, two concentric vertical current conducting tubes inclosing the material under treatment, a bottom conducting block on which the tubes rest, an upper con ducting block 'to which the said tubes are fixed and means for raising the upper block and the tubes to open the furnace.

12. In an electric resistance furnace for refractory materials, two concentric Vertical current conducting tubes inclosing the material under treatment, a bottom conducting block on which the tubes rest, an upper conducting block to which the said tubes are fixed. means for raising the upper block and the tubes to open the furnace, an external casing receiving the furnace and a plurality of air blast funnels inside the said casing and directed toward the center of the furnace.

In testimony whereof I ailix my signature in presence of two witnesses.

GOTTLIEB GMUR-ZEHNDER.

Witnesses HY. WIEFLISBACH, Snzcrn. ANGST.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patent: Washington, D. 0."

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