US953774A - Vacuum resistance-furnace. - Google Patents

Description

A. 0. APPELBERG. VACUUM RESISTANCE PURNAGE.

APPLICATION FILED JULY 2, 19

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A. '0. APPELBBRG.

VACUUM RESISTANCE PURNAGE.

APPLIOA'TION FILED JULY 2, 1000.

953,774e Patented Apr. 5, 1010.

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UNITED sfrafrns PATENT emmen.v

AXEL o. APPELBEBG,

OF SCHENECTAY, NEW YORK, ASSIGNOB. TO GENERAL ELECTRIC; COMP-ANY, A CORPORATION 0F YORK.

VACUUM RESISTANCE-runnen.

speciaeauon of Lettera Patent. i Iatenfted. Apr., 5, 1910. Application filed July 2, 1906. Serial No. $24,391.

To all whom it may concern:

Beit known that I, AXEL 0. A PPEIBERG, a subject of the King of Sweden, residing at Schenectady, county. of Schenectady, State -of New York, have -'invented certain new' and useful Improvements in Vacuum Resistance-Furnaces, of .which the following is aspecification.' v

This invention relatesto an improvement in electric furnaces and particularly to means whereby a temperature may be produced approaching that at which some o the so-called high fusing metalsdisintegrate vor va orize.' f

'ghe furnace may be used for the fusion or treatment of the more refractory metals and compounds, and includes 1neansfor protecting the charge under treatment from oxidation or other change which might result `from contact with air or other atmosphere at the high temperature of treatment.

My improved furnace is of the resistance type and is provided with a resistance con-V fication, in which- Figure 1 vis a perspective view of one type.4

of furnace with certain of the parts shown in sectiongyFig. 2 is a lan view taken on the line 1--1 of Fi l; gig.. 3 is a -representation of the crucib e to be heated and of the resistance conductors Vand the surrounding refractory shield; Fig. t is a detail illustrating thc connection between a resistance conductor and the metal block by which it is supported; and Fig. 5 is a sectional eleva# tion o a modified type of furnace in which the resistance heater 1s tubular 1n form.

rlhe furnace shown 1n Fig. 1 com rises an air tight metal chamber 1 fitted wit a cover vbrass tubes t an .from by mica bushings 9, with the exception lhave hereinafter described the cover to near the bottom of the chamber and is then bent in a circular form and passesnpward and out again through the cover. This tube is insulated from the cover and serves to connect the resistance members of the furnace with one side of an electrical circuit. A similar tube 5 is arranged in circular form near the` top of the evacuated chamber to 'support the upper ends ofthe heatingA members.` vThese heating members 6V conslst of metal rods produced as hereinafter described, and clamped at their endsin blocks 7 of the same material, vthe latter being secured to iron clamps 8 by suitable clips. The clam s 8 are mounted on the 5 and are insulated there.

of the clamps 10 and 11 which connect with the end conductors of the group; these are -mounted directly on the brass rods' and thereby establish a connection forv current from the source of pcwerthrgugh the cup of rods in series. They may convenientlyv be made of copper.

Then the heatin conductors are made oi tungsten they maye pressed to the desired form from finely powdered tungsten, but for convenience in manufacture it is some- 'times desirable to add a small quantity of binding material to the tungsten powder and then squirt or 'mold the mixture into rods and blocks necessary for the construction of the furnace. A 56% glucose solution is a suitable binder and may be added tol-the tungsten' powder in theproportion of about 5 yparts by weight., When glucoseis used I prefer toadd to the mixture about 10% of tungstic oxid so that when themxture is heated up in the furnace there ma be enough oxygen .present to eliminate al l,carbon and yield a refractory body of ure tungsten. This mixture when rst m0 ded or pressed isl rather brittle and inclined to crumble but 'ind thatby heating itin a vacuum to about 1390" C., l can com letely change its 'characteristics and ren er it strong and relatively tough. After this treatment it can be machined and otherwise manipulated much like artificial raphite. Before the furnace is ut into regular o 'eration l .consider it' a visable to heat t ese tungsten parts toatemperature considerably hi h'er than 13000V (lin order to drive ont al' vaporizable components such as unreice loe

a plurality of superimposed rings 12 of tory bushings 13.

tungsten. These parts are shown 1n F ig. B disposed in proper relation to the refractory heaters 6. Therings12 constitute a shield to prevent `dissipation of heat toward the metal walls of the chamber and to reflect radiant heat on the cruciblevlocated Within the heating space. The rings 12 may be conveniently insulated' from other parts of the apparatus by non-conductive and refrac- 'lhe crucible 14 containing the charge to be melted may be supported on a tungsten .pedestal l5 carrying a cap 16. The pedestal 15 may be conveniently supportedby iron bars 1'? engaging with the lower brass pipe 4 and insulated therefrom. The brass pipes 4 and 5 serve not only to transmit current to and from the refractory conductors but they also serve as means for carrying a cooling'liqhid through blocks 8, l0, and l1 whereby these parts are maintained at a relatively low temperature even though the resistance conductors are run at lan exceedingly high heat. y

To insure a good connection between the refractory heaters G and the blocks f in which they are mounted, l may use the means of connection shown in Fig. 4. rlhe lower block is provided with a cup 18 filled with tungsten powder in which the lower end of the refractory heater is embedded.

The powder is pressed firmly in position by.

means -of a tungsten bushing.y 19 pushed down on top of the powder. nd that such a joint becomes vvery strong after the initial operation of the furnace, because of sintering or similar action between the particles of the powder whereby, the entire joint becomes relatively solid and strong and insures a good electrical connection to the refractory heater. At the top of the 'heater the joint is similarly made except that the heater enters the cup of tungsten 'powder from below. As an alternative means of connecting the heaters I may clamp'theends between tungsten blocks. y

The furnace may be waterc'ooled-'-aiid may be provided with a suitable `peep hole 21 covered with a plate of mica 22. l"

The modication shown in- Fig. 5. includes many of the features shown in Fig. 1, but is provided with a tubular heater 1n place of the series of rods heretofore described. This tubular heater 23 is clamped atthe to in a tungsten block 24 and the latter lis e ectrically connected to a U-sha ed tube 25 of brass or other metal. At the ottom the refractory tube is mounted in a tungsten cup 26 and the latter is clamped between suitable tungsten blocks 27, one of which is shown in the drawings. A second metal tube 28 serves as a means for connecting the lower end of the heater with the electrical circuitand also serves to support vthe annular shield 29 which surrounds the heating tube and concentrates the heat within the tube.I A tungsten pedestal 30 is mounted within the tube to serve as a support for a crucible or other article to be heated. I prefer lto insulate this pedestal from other parts of the heater by a lava bushing 31 and I prefer to insulate the tungsten shield from the supporting clamps 32 by vsimilar bushings to decrease the tendency for dissociation of the heater or of theheated parts because of the liberation of charged particles at the enormous temperature to which these elements are subjected during normal operation of the furnace. If

desired, the tubular heater may be divided by a helical slot to increase the voltage across the heater for any given current.

I find either of the modications above described to be very serviceable for the treatment of the more refractory metals and materials and for the production of a predetermined and controllable temperature. The furnace may be used for the continued heating of tungsten without danger of contaminatingthc charge by vapors or charged particles given mi by the heating elements of the furnace. As the entire evacuated chamber is free from carbon, the highest temperature may be produced without danger of contaminating the charge with carbon, or producing a carbid from the ma'.-

terial under treatment.

3. vThe combination of an air-tight cham-l ber, means for continuously exhausting air from said chamber, and a refractory heating member mounted in said chamber and consisting of lcompressed tungsten powder.

4. ln a vacuum furnace, a heating member consisting of compressed tungsten powder, Ameans for supporting material to be heated in proximity to said heating mem- '.ber, and terminalsfor the heating member consisting of tungsten block"s.

5. ln a vacuum furnace, a heating space having tungsten walls', and a refractory heater therein of substantially pure tungsten. f

6. The combination of an air tight chaine bei', means for supporting material to be treated in said chamber, and means out of contact with said material for heating it to a temperature approaching the fusing point of tungsten, in a space free from carbon.

7. In avacuum furnace, a resistance conductor of compressed tungsten powder, and material to be treated placed in proximity to said heater and receiving radiant energy therefrom.

8. A vacuum furnace of the resistance type having an incandescent conductor of substantially pure tungsten. I

9. A vacuum furnace of the resistance type having an incandescent conductor consist-ing substantially of pure -n'ietal powder sintered into a coherent body and having a fusing temperature as high or higher than the temperature at which carbon appears to disintegrate. p

10. The combination of an air-tiglit chamber, means for supporting a charge of me- I tallic material therein, and a resistance conductor for heatincr said charge said conductor consisting of material the vapor of which is chemically inert with respect to the charge under treatment at temperatures approaching the fusing. temperature of the more refractory metals.

11. A furnace of the resistance type hav.- ing a furnace chamber inclosing a tubular resistance conductor of 'substantially pure tungsten. y

1,2. A vacuum furnace of the resistance type having a furnace chamber inclosing a tubular resistance conductor -of substantially pure tungsten Within which the material to be heated can be introduced.

18. The. combination of an evacuated chamber, a tungsten tube therein, means for supplying current to said tube to heat the saine, and means for -supporting material within said tube but out of Contact therewith. ".f-

14. A tubular resistance member of pure 'tungsten having a bore large enoughto ad mit a Crucible.

15. A tubular resistance heater of pure tungsten having a helical slot.

In Witnessl whereof, I have hereunto set my hand this 30th day of June, 1906.

AXELy O. APPELBERG.

VitneSSes y .EDWARD WILLIAMS, Jr., ARBAB. MARVIN, Jr.

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