Патент USA US2404060код для вставки
July 16, 1946. _R. D. HALL ETAL -HIGH TEMPERATURE FURNACE Filed Feb. s, 1944 2,404,060 Patented July 16, 1946 2,404,060 NIT-ED 2,404,060PÀTÍEN T 'OLFÍF l HIGH TEMPERATURE >FURNACE -Roy lI). ~` Hall, fMillington, and ~Emìlîo Romanelli, Bloomfield, N. 'J., assignors to Westinghouse îEle‘ctr'ic Corporation, East -Pittsburgh, Pa., .fa Vacorporat'ion ‘of Pennsylvania Application 'February 3, 1944,’ Serial No. 520,874 ‘7 Claims. (CLIS-_20) ‘1 'This invention relates to furnaces, A‘and more particularly, to such adapted *for temperatures high enough 'to sinter andp'therwise heat treat, tungsten and molybdenum. The principal object of our invention, 'gener ally considered, isa furnace -adapted'to-eñiciently producetemperatures above `1700° C., 'whereby it may beused'for sintering and-/or vheat treating refractory metals such las vtungsten and’molyb dehum. Another object of our inventionis aiiurnace for We have designed a »furnace capable oi pro vidingtemperatures up to 2000o C. where molyb denum is used as a heating element, and up to about 2500D C. where tungsten is so used. These furnaces >are particularly adapted ‘for treatment of refractory articles, as in ~following the inven tion describedand claimed in the Hall et al. ap plication, Serial No. 511,392, liled November 23, 1943, now replaced by- Serial No. 579,080, nled Feb ruary-Zl, i945, which refers to the lfurnace which is here claimed. Theprinciple involved in our furnace is to use the radiant Aheat from wires, bars or Slabs of high tempertures comprising an 'element formed of tungsten or 'molybdenum wire or rods _adapted molybdenum or tungsten disposed around the to be heated to incandescence bythe passage of electric current therethrough and arranged to 15 body 'to ¿be heated. 'Such heating means is, `for insulating purposes, surrounded by reflectors dis surround’the material to be' heated, and a series of posed at appropriate distances, the ñrst reflector enclosing reiiecting baffles and associated _cover being of sheet vmo'ly’bdenum or tungsten, the platesv supported on a refractory block, with means former `of which is generally satisfactory, the re for sealingsaid enclosure and admittingprotec tive atmosphere thereto, `as well vas means ?vfor conveniently removing the enclosure for the ap plication and `withdrawal of the material being treated. Other objects and >advantagesof the invention, relating to the particular arrangement andcon struction of the various parts, `will become ap parent as the description proceeds. Referring to the drawing: maining reflectors being-of molybdenum and/or stainless steel either chromium plated or not, finally ending up with one or more silver plated steel and/or copper reflectors. The last reñect ing means may be Veither arseparate unit or part 25 of a «Water-cooled jacket used as an outer cover rfor ït'he furnace. The heating element is en closed in these layers of reflectors and a _peep hole is desirably provided at the end of a tube for purposes of temperature measurement. The Fig. 1 is an axial sectional view„partly.in ele vation, of a furnace embodying our'invention and 30 vcovering of suchva lpeep'hole-device is _preferably of‘quartz or high melting point, low expansion showing an article in place therein, as representa glass, and removable »for purposes of cleaning. tive of material which maybe heat treated. The v`heating elements of such furnaces are Fig.'2 is a horizontal 'sectional view on the line mounted so 'as to take up the expansion upon II-Il of Fig, 1„in the direction .of the'arrows. Fig. 3 is an _axial sectional View of the peep 35 heating without distortion. It is desirable to have'twoïha'lf-Windings of approximately parallel hole eyepiece assembly. elements. These wires or rods, being parallel, form elements of a cylindrical surface of such diameter that the article to be treated, when withstanding such ‘high temperatures. 40 placed at or near the axis of said surface, will get relatively uniform heat. If necessary, the Wires Beryllia, Zirconia and .thoria will withstand or rods may be wound with tungsten or molyb higher than usual temperatures, lbutthe ñrst ,is denum wire -at the points Where supported in very expensive andzirconia and thoria vare dith korderfto cool them, Iso that refractories such as cult to use because of vthe lack of shock resist ance. Carbon resistor furnaces, .known as »Arsem 45 alumina canïbe used for support. ‘Where rods of tungsten :or molybdenum vare used, connectors of furnaces, are not usable ’with .hydrogen Yor other drilled ‘cars can be employed. The entire furnace protective atmosphere ,required for fabrication »of Furnaces designed for temperature above about 1700o C. cannot contain the ‘usual type _of re fractories because `the latter are incapable vof such materials‘as‘tungsten and molybdenum. Tube furnaces involving molybdenum or tung yand shell or jacket is desirably mounted as a unit and designed to be placed on a flat plate 50 of refractory material. IThe shell must be ex terial such as wire drawn through Vsuch tubes so tended kfar enough below'the heated elements to heated. These are Asatisfactory ‘for small long use the furnace ~for Aprotective atmospheres such as hydrogen, nitrogen, ‘argon or a mixture of articles but lcannot be adapted for ‘larger Work. sten tubes may be heated electrically and ma Induction Yfurnaces are diñicult to use with _pro tective `atmospheres Vat high temperatures.Í gases, or evacuated and used asa vacuum iur 55 nace. For vacuum purposes ’the outer contact 2,404,060 3 4 of this furnace shell and plate can be sealed, as by means of a suitable cement. suitably insulated therefrom, said device being strung down and up over the annular, desirably The stand carrying the base plate is desirably equipped for exhausting or introducing the at mospheres required and the plate carries on its Alundum, lower and upper spool members 69 and 1| formed with radial elements 12 and 13 around which the individual loops pass between slots face a container or stand for supporting the ma therebetween, said slots being subsequently closed terial, article, or articles, to be heat-treated. by desirably Alundum retainer rings 14 and 15. The spools and rings are desirably bound together This stand may be made of molybdenum or tung sten coated with beryllium oxide or thoria, either by covering plates 16 and 11, of molybdenum or as discs or powder at the point of contact with .10 other suitable material. the material to be heat-treated to prevent weld The heat developed by the resistance element ing. The purpose of this stand is to carry in is conserved by a series of bailies, the inner one the optimum heat zone the materials undergo 18 desirably comprising sheet molybdenum pol ing treatment. ished on both sides, or if very high temperatures For purposes of loading the furnace, arrange 15 are desired similarly polished sheet tungsten may ments can be made for either raising the insulat be used. The next baffle 19 is desirably formed of ing housing or lowering the stand, whichever is stainless steel, chromium plated on both sides more convenient. Furnaces of this type are satis or of molybdenum. The remaining three baffles factory to furnish temperatures sufficiently high 8|, 82 and 83 are desirably formed of steel sheet, to sinter or coalesce tungsten to high density for 20 silver plated on both sides, all of the baffles be fabrication purposes if the proper protective ing supported from the upper plate 84 ofthe and/or reactive atmosphere is used during the treatment. Referring to the scale drawing in detail, like parts being designated by’ like reference char cylindrical water jacket, also desirably formed of steel, silver plated on both sides, as by means of bolts 85 and 86 and top cover plates 19', 8|' and 82,', desirably respectively formed of ma acters, there is shown one embodiment of our in vention comprising a radiation type furnace 42 consisting of a base 43 which may be formed of “transita” other suitable refractory, or even a metal plate where a vacuum is desired, upon 30 terial like that of the plates 19, 8| and 82. In order to allow for inspection of the article, such as that designated 3|, during the heat treat `ment thereof, the upper plates 19', 8|', B2' and 84, as well as the plate 6D, are all provided with which is supported a preferably circular plate 44 aligned apertures preferably coaxial with the fur of Alundum, or the like. The plate 44, in turn, nace and the vertical section of the inlet pipe 81, holds a hollow cylinder 45 of beryllia or zirconia, to the top of which a valve 88 is shown applied. carrying a supporting cap 46 of similar material, The housing 9| of this valve is desirably pro on which during the sintering operation the 35 vided with a horizontal annular web portion 92 - treated articles, (or article) such as the refrac terminating at` its outer end in an upstanding tory metal worm 3|, rests. threaded iiange portion 93 providing a socket or The furnace 42 comprises an outer fluid-cooled bezel for the reception of a transparent eye casing 41, which may consist of hollow copper piece 94, desirably formed of quartz or high-melt cylinders 4B and 49 coaxially arranged and con ing-point glass, as shown in Fig. 3. The eye nected by annular spacing elements 5| and 52 piece 94 desirably rests on packing means 95 of brass, or other suitable material, brazed or and is secured in place by an annular retainer otherwise suitably connected thereto, forming an 96, thereby providing a peep hole device for sight annular space through which water may be cir ing down axially of the furnace, through the eye culated, as from the inlet pipe 53 to the outlet ' piece 94, the valve 88 when opened, the vertical pipe 54. The inner plate 49 may extend into the section of the inlet pipe 81, and the apertures annular cavity 55 at the base 43 for support and previously referred to in the upper horizontal plates. sealing, as by said cavity holding a sealing liquid, not shown, or if evacuated or holding gas under From the foregoing disclosure it will be seen pressure, by a suitable cement. The inner sur that the furnace may be used to heat articles of face of the water jacket plate 49 is desirably tungsten or other refractory metal, to the high silver plated to minimize the radiation absorbed temperatures necessary to effect the final sinter thereby, and closed at its upper end by a water ing operation, by radiation from an incandescent cooled hollow plate 56 formed of suitable metal, refractory resistance element, the heat being con such as copper or steel. served by polished ancl/or bright plated baffles, The top plate 56 may be sealed inside of and to the whole enclosed in a water jacket, and the ar the cylinder 49, carry a refractory or transite ticles or material during treatment being sur plate 60, and be provided with studs 51 and 58 rounded by a protective atmosphere, such as to which chains or cables 59 and 6| connect for wet hydrogen, introduced through the upper pipe raising and lowering the same with respect to the 81, and exhausted through the lower pipe B9. base and any article, or articles, being treated. Although a preferred embodiment of our in To facilitate this raising and lowering operation, vention has been disclosed, it will be understood the water jacket has upper and lower stiffening that modifications may be made within the spirit and scope of the appended claims. rings 62 and 63 secured thereto, as by welding We claim: or other suitable means, and through which guides (i 5 64 and 65 pass, the lower ends of said guides be- " 1. A furnace for high temperatures comprising ing embedded in the base 43. Alternatively, the a refractory metal element consisting of a series studs 51 and 5B may connect directly with one of the elements 5| and 62. The heating means for the furnace, in theu|present embodiment, comprise a molybdenum or tungsten resistance device, which may be a wire 66 (or if of a large size, rods suitably connected in series) receiving power from leads 61 and 68 passing through the water-cooled _plate 56 and_ of sections, to be heated by the passage of elec- - tricity therealong, disposed as the elements of a hollow cylindrical surface and arranged to di rectly radiate heat upon material to be treated, and a series of reflecting hollow cylindrical ele ments coaxial with said metal element, the inner of said elements being formed of polished molyb denum, intermediate elements consisting of stain A2,404,060 5 6 less steel, chromium plated on both sides, and outer elements consisting of sheet steel, silver with said peep holes and passing through said casing, a valve the housing of which is secured to said pipe, said housing having an outer socket, plated on both sides. 2. A furnace for high temperatures comprising a refractory metal device to be heated to incan descence by the passage of electricity therealong, elements thereof being arranged to surround and directly radiate heat upon material to be treated, a base of refractory material formed with a groove, a series of vertically movable reflecting baffles and an outer casing surrounding said heated element, a pair of stiffening rings secured to said outer casing, rods with their lower ends embedded in said base and guidably passing through holes in said rings, and at least one of said baffles extending below the lower edges of the others and telescopingly received in said groove when in normal position. 3. A furnace for high temperatures compris ing a refractory metal element consisting of a series of sections, to be heated by the passage of electricity therealong, disposed as the ele ments of a hollow cylindrical surface and ar and an eye piece in said socket and through which the material undergoing treatment may be viewed when the valve is open. 5. A furnace for high temperatures comprising a refractory metal element shaped as a series of sections, to be heated by the passage of elec tricity therealong, and arranged to directly radi ate heat upon material to be treated, and a series of reflecting hollow cylindrical elements succes sively surrounding said metal element, the inner of said elements being formed of molybdenum, intermediate elements consisting of stainless steel, and outer elements consisting of sheet steel. 6. A furnace for high temperatures comprising a refractory metal device, to be heated to incan descence by the passage of electricity therealong, arranged to form elements of a hollow gener ally cylindrical surface to surround and directly irradiate heat upon material to be treated, a base of refractory material formed with a groove, a ranged to directly radiate heat upon material to series of reflecting baffles surrounding said device, be treated, a series of surrounding reflecting hol at least one of said baffles extending below the low cylindrical elements and an outer casing dis remainder and telescopically receivable in said posed coaxially therewith, stiffening means se groove, and means for guiding said bañies during cured to said casing, means closing the upper ends raising and lowering thereof with respect to said base. of said reflecting elements, a base, rods with their lower ends embedded in said base and guidably 30 '7. A furnace for high temperatures compris passing through holes in said rings, and means ing a refractory metal device, to be heated to for lifting said reflecting elements and associ incandescence by the passage of electricity there ated refractory metal element, with the stiffen along, arranged to form elements of a hollow ing means sliding on said rods, in order to allow generally cylindrical surface to surround and for the introduction and removal of the mate- ‘ directly irradiate heat upon material to be treated, a series of surrounding reflecting hollow cylin rial to be treated. 4. A furnace for high temperatures compris drical elements of varying diameters disposed ing a refractory metal element to be heated to coaxially with respect to said surface, a base for incandescence by the passage of electricity there said furnace, means for lifting said reflecting along, arranged to surround and directly radiate 40 elements and associated refractory metal device heat upon material to be treated, a series of with respect to said base, and means to guide reflecting baffles and an outer casing surrounding said elements during raising and lowering oper said refractory metal element, means closing the ations. upper end of said series of baffles, a series of peep ROY D. HALL. holes through said closing means, a pipe alined 45 EMILIO ROMANELLI.