US3571478A - Vacuum furnace - Google Patents

Vacuum furnace Download PDF

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Publication number
US3571478A
US3571478A US844942A US3571478DA US3571478A US 3571478 A US3571478 A US 3571478A US 844942 A US844942 A US 844942A US 3571478D A US3571478D A US 3571478DA US 3571478 A US3571478 A US 3571478A
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United States
Prior art keywords
furnace
foil
chamber
spiral
set forth
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US844942A
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English (en)
Inventor
William P Teagan
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Thermo Fisher Scientific Inc
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Thermo Electron Corp
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Publication date
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D11/00—Arrangement of elements for electric heating in or on furnaces
    • F27D11/02—Ohmic resistance heating
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D11/00—Arrangement of elements for electric heating in or on furnaces

Definitions

  • radiation shielding In various high-temperature furnace constructions proposed heretofore, radiation shielding, if provided at all, has typically been'in the form of a plurality of discrete shields which are rigid and self-supporting.
  • the number of such shields has typically been limited by the bulk and size they add to the furnace in view of the thicknesses of the shields themselves and the spacing required for rigid support.
  • prior art shielding arrangements have required a substantial amount of material in the shields themselves and the cost of this material may substantially raise the price of furnaces designed for high-temperature operation.
  • a high-temperature furnace employing radiation shielding; the provision. of such a furnace in which the shielding is relatively compact; the provision of such a furnace in which heat losses are relatively small; the provision of such, a furnace which requires a relatively low power input to achieve a given temperature; the provision of such a furnace which is relatively inexpensive; and the provision of such a furnace which is easily constructed.
  • a radiation-shielded furnace involves chamber defining means including a multitum spiral of a foil of a refractory metal with a sparse scattering of discrete particles of a relatively nonconducting material separating adjacent turns of the foil.
  • the first turn of the spiral encompasses a volume which forms the heating chamber of the furnace.
  • Each open end of the spiral is closed by a respective cover and a heater is provided for generating heat in the chamber.
  • FIG. I is a side elevation in section of a vacuum furnace according to this invention.
  • FIG. 2 is a sectional view of the sidewall of the furnace taken substantially on the line 22 of FIG. ll;
  • FIG. 3 is a view, taken substantially on the line 3-3 of FIG. ll showing the upper cover with heater;
  • FIG. 4 is a sectional view illustrating another embodiment of the invention.
  • FIG. 5 is a plot comparing the temperature/power characteristics of a furnace according to this invention with a conventional Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.
  • the furnace illustrated there is of generally cylindrical configuration and comprises a generally tubular member it closed at each end by a respective cover t3, and 15.
  • the sidewall-defining tubular member It includes an outer metallic shell 17 and a radiation shield 19.
  • the radiation shield 19 comprises a spiral 21 of a foil of a suitable metal with adjacent turns of the foil being separated or spaced by a sparse scattering or dusting of discrete particles 23.
  • Particles 23 are preferably of a relatively nonconducting material such as a ceramic powder.
  • such a radiation shield may be constructed by scattering a ceramic powder on the surface of a strip of foil as it is wound up on a suitable form.
  • foil as used herein and in the claims should be understood to mean a layer of metal which is not more than 0.005 inches thick.
  • a refractory metal such as tungsten, molybdenum or tantalum may be employed for the foil 21 while furnaces for use at lower temperatures, e.g. annealing furnaces, may be constructed with a foil of a metal such as titanium, stainless steel or nickel.
  • the covers 13 and 15 are constructed in an analogous manner and comprise a backing plate 31 and a radiation shield 33.
  • the shields 33 may also comprise multiple layers of foil, the layers being spaced by a ceramic powder and being wired to the backing plate 31.
  • Heat is generated within the chamber of the furnace by means of a resistance heater 35 which comprises a pair of strips of tungsten wire screen 37 and 39. Each of the strips is draped between a respective input electrode 41 and 43 and an intermediate support electrode 45, the electrodes being mounted on respective feedthrough terminals 47-49.
  • This heater arrangement has the advantage that the heating chamber is left relatively clear for the insertion of a workpiece.
  • a relatively simple heater of this type may be employed since losses from the furnace are relatively'low as compared with conventional constructions. In other words, a relatively high temperature can be obtained with a relatively low power input. In addition, longlife is obtained, heaters of this type having been operated for hundred of hours at 2000 C.
  • Tungsten wire screen suitable for use as the resistance heating elements 37 and 39 is readily available for other purposes and thus special purpose heating elements need not be custom fabricated at considerable expense.
  • wire mesh heating elements can be hung alongside the periphery of the tubular member Ill with suitable electrodes being provided at v the ends of the strips for interconnection and for the application of electric power.
  • the furnace is mountedon legs 5! within a conventional bell jar 53 which is then evacuated by means of a pump as indicated diagrammatically at 55.
  • the radiation shield I9 comprised 20 layers or turns of molybdenum foil and 20 layers of tungsten foil.
  • the foils were 0.001 inches thick and adjacent layers were separated by sparsely distributed zirconia oxide powder of size such that the resulting average thickness for each radiation shielding layer was about 0.0025 inches.
  • the total thickness of the radiation shield 19 was only about 0.1 inches thick. The heat losses from this furnace were low enough so that a temperature of 2,000 C. was
  • a plot of temperature as a function of input power for this furnace is indicated at A in FIG. 5.
  • B the temperature/power characteristic of a conventional furnace having a heating chamber of comparable size, i.e. 4- inches in diameter by 7 inches high.
  • This conventional furnace is radiation shielded by means of five self-supporting tungsten shields which together form a shield wall about l /sinches thick. It can thus be seen that relatively efficient operation was provided by the present invention in a relatively compact structure. Further, the application of power for heating was facilitated by the use of the wire mesh heater described previously which presented a relatively high impedance to the power supply, e.g. about 1 ohm at L800 C.
  • the heating elements were constructed of standard,
  • tungsten screen with a wire size of 0.004 inches and a 35 wire per inch mesh.
  • spiral should be understood to include wound radiation shielding foil when the overall cross section is other than circular, e.g. rectangular.
  • FIG. 4 An alternative radiation shield construction is illustrated in the sectional view of FIG. 4. This sectional view is taken along a plane parallel to the axis of the respective spiral rather than transversely thereto as with FIG. 2.
  • the adjacent turns of a spiral of a metal foil 61 are separated by fine wires 63 of relatively nonconducting material, either metallic or nonmetallic which are wound up in spirals with the foil 61.
  • the separation between the adjacent fine wires 63 in each layer is preferable somewhat random so that the wires is adjacent layers do not lie in alignment with one another.
  • each turn of the wires 63 can conduct heat locally from one layer to the next and thereby effectively short circuit that one radiation shield layer, it will be seen that the total effect on the overall radiation shield is quite small since the heat thusly transmitted by one wire at a given point does not as readily penetrate any of the other layers. It will be understood 1 that the lateral paths along the foil are relatively long as com- 'pared with the transverse dimensions and are thus inefficient conduction paths. As with the first example, the randomly spaced fine wires locally space and support the adjacent turns of the foil 61 so that a relatively thin foil, which would not be self-supporting, may be used.
  • a radiation-shielded furnace comprising:
  • chamber-defining means including a multiturn spiral of a foil of a refractory metal with a sparse scattering of discrete particles of a relatively nonconducting material separating adjacent turns of said foil, the first turn of said spiral encompassing a volume which forms said chamber;
  • a heater for generating heat in said chamber.
  • a radiation shielded furnace, said fumace comprising:
  • chamber-defining means including a multiturn spiral of a foil of a refractory metal with a sparse scattering of discrete particles of a relatively nonconducting material separating adjacent turns of said foil, the first turn of said spiral encompassing a volume which forms said chamber;
  • a heater including at least a pair of electrodes and a woven wire mesh resistance heating element extending between said electrodes for generating radiant energy in said chamber.
  • a radiation'shielded vacuum furnace comprising:
  • chamber-defining means including a multiturn spiral of a foil of a refractory metal with a sparse scattering of discrete particles of a relatively nonconducting ceramic material separating adjacent turns of said foil, the first turn of said spiral encompassing a volume which forms said chamber;
  • a heater including at least a pair of electrodes and a woven wire mesh resistance heating element extending between said electrodes for generating radiant energy in said chamber;
  • each of said covers includes a plurality'of layers of a refractory metal foil separated by a sparse scattering of discrete particles of a ceramic powder.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Resistance Heating (AREA)
  • Furnace Details (AREA)
  • Heat Sensitive Colour Forming Recording (AREA)
US844942A 1969-07-25 1969-07-25 Vacuum furnace Expired - Lifetime US3571478A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US84494269A 1969-07-25 1969-07-25

Publications (1)

Publication Number Publication Date
US3571478A true US3571478A (en) 1971-03-16

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US844942A Expired - Lifetime US3571478A (en) 1969-07-25 1969-07-25 Vacuum furnace

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US (1) US3571478A (enrdf_load_stackoverflow)
JP (1) JPS491176B1 (enrdf_load_stackoverflow)
DE (1) DE2034200B2 (enrdf_load_stackoverflow)
GB (1) GB1266096A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3823685A (en) * 1971-08-05 1974-07-16 Ncr Co Processing apparatus
US3940245A (en) * 1974-12-18 1976-02-24 Autoclave Engineers, Inc. Convection shield for isostatic bonding apparatus
US3971875A (en) * 1974-01-04 1976-07-27 General Dynamics Corporation Apparatus and method for vacuum hot press joining, compacting and treating of materials
US4217856A (en) * 1977-07-08 1980-08-19 Balzers Aktiengesellschaft Fur Hochvakuumtechnik Und Dunne Schichten Vacuum evaporation apparatus
US5987053A (en) * 1997-09-03 1999-11-16 Webb; Richard Dyson High temperature air cooled vacuum furnace
US20170074588A1 (en) * 2015-09-11 2017-03-16 T-M Vacuum Products, Inc. Vacuum furnace with heating vessel in multiple orientations and method thereof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU207585U1 (ru) * 2021-04-20 2021-11-02 Федеральное государственное автономное образовательное учреждение высшего образования "Уральский федеральный университет имени первого Президента России Б.Н. Ельцина" Нагреватель для лабораторной цилиндрической электропечи

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2308945A (en) * 1939-05-05 1943-01-19 Hartford Nat Bank & Trust Co High-frequency induction furnace
US3257492A (en) * 1965-07-15 1966-06-21 Hayes Inc C I Electric furnace construction
US3409730A (en) * 1966-06-17 1968-11-05 Nasa Usa Thermal radiation shielding

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2308945A (en) * 1939-05-05 1943-01-19 Hartford Nat Bank & Trust Co High-frequency induction furnace
US3257492A (en) * 1965-07-15 1966-06-21 Hayes Inc C I Electric furnace construction
US3409730A (en) * 1966-06-17 1968-11-05 Nasa Usa Thermal radiation shielding

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3823685A (en) * 1971-08-05 1974-07-16 Ncr Co Processing apparatus
US3971875A (en) * 1974-01-04 1976-07-27 General Dynamics Corporation Apparatus and method for vacuum hot press joining, compacting and treating of materials
US3940245A (en) * 1974-12-18 1976-02-24 Autoclave Engineers, Inc. Convection shield for isostatic bonding apparatus
US4217856A (en) * 1977-07-08 1980-08-19 Balzers Aktiengesellschaft Fur Hochvakuumtechnik Und Dunne Schichten Vacuum evaporation apparatus
US5987053A (en) * 1997-09-03 1999-11-16 Webb; Richard Dyson High temperature air cooled vacuum furnace
US20170074588A1 (en) * 2015-09-11 2017-03-16 T-M Vacuum Products, Inc. Vacuum furnace with heating vessel in multiple orientations and method thereof

Also Published As

Publication number Publication date
DE2034200A1 (de) 1971-02-18
DE2034200B2 (de) 1972-09-28
JPS491176B1 (enrdf_load_stackoverflow) 1974-01-11
GB1266096A (enrdf_load_stackoverflow) 1972-03-08

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