US3581144A - Metal-clad insulated electrical heater - Google Patents
Metal-clad insulated electrical heater Download PDFInfo
- Publication number
- US3581144A US3581144A US811067A US3581144DA US3581144A US 3581144 A US3581144 A US 3581144A US 811067 A US811067 A US 811067A US 3581144D A US3581144D A US 3581144DA US 3581144 A US3581144 A US 3581144A
- Authority
- US
- United States
- Prior art keywords
- metal
- heater
- molybdenum
- wire
- tungsten
- 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
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/13—Solid thermionic cathodes
- H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
- H01J1/22—Heaters
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/42—Heating elements having the shape of rods or tubes non-flexible
- H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
- H05B3/50—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material heating conductor arranged in metal tubes, the radiating surface having heat-conducting fins
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
- H05B3/688—Fabrication of the plates
Definitions
- the present invention relates to electrical heaters and, in particular, to a low mass insulated heater that can be bonded with low thermal drop to an object to be heated and a method of manufacturing such heater.
- a metal powder is sintered or deposited on the underside of the cathode to provide interlocking arrangement with the refractory material. While such structures show marked improvement over prior ones in their rapidity of heating and resistance to mechanical shocks, because of the various expansions of the materials used in assembly and in the procedure used for bonding, it is difficult to avoid warping of the cathode lid, in many instances.
- the cathode In microwave electron discharge devices, the cathode is spaced very close to associated grid electrodes and any warping of the cathode structure impairs the operation of the device.
- my invention consists in constructing an insulated electrical heater by forming coplanar turns of a heater wire, covering the wire with a thin, tightly adhering coating of an insulating material, depositing a metal overcoating on the insulated material, and applying a thin layer of brazing or alloying material to at least one surface of the overcoated coplanar turns which then is positioned adjacent the object to be heated and heated until a tight, impervious bond is formed between the object and the composite heater, the various materials of the heater structure and the object being chosen to have closely similar thermal expansion characteristics.
- FIG. 1 is a perspective view illustrating the method of manufacturing the metal clad insulated heater
- FIG. 2 is a side view of the heater of FIG. 1 showing a thin layer of additional metal applied to one surface of the heater;
- FIG. 3 illustrates another configuration of the heater of my invention.
- FIG. 4 illustrates a cathode for an electron discharge device embodying the heater of my invention.
- a heater wire 1 is formed into a layer of coplanar turns 2 of the wire. While any desired configuration of the wire may be used, in this figure the layer is shown as comprising a plurality of spiral turns 2 of wire 1. After the wire is formed into the desired configuration, it is covered with a coating of insulating material 3. The coating may be applied by any conventional techniques, such as flame spraying, chemical vapor deposition, or cataphoresis. The chemical vapor deposition technique is particularly suited since it provides a very thin impervious coating on the wire, the coating having a high dielectric strength. After the insulation has been applied to the wire, the insulated wire is covered with an overcoating 4 of metal.
- Overcoat 4 may likewise be applied to the insulated wire by flame spraying, schoop spraying, or any other suitable deposition process.
- the material is applied in the form of a metal oxide and later converted to the pure metal by heating in a reducing-atmosphere, such as dry hydrogen.
- the next step in the process is to coat one surface of the layer of wire with a metal powder 5 and braze it to or alloy it with the object or surface 6 which is to be heated.
- the object to be heated comprises a flat metal plate 6.
- the resultant structure is heated so that the heater layer 2 and powder 5 are brazed or alloyed to plate 6.
- layer 5 may be attached to the composite heater prior to its attachment to plate 6.
- the wire 1 may comprise any suitable heater wire, for example, tungsten, nickel, or molybdenum. l have found molybdenum particularly suitable for constructing a cathode structure for an electron discharge device since it is ductile and can be easily shaped into a layer of coplanar turns.
- the material of insulating coating 3 is selected so that its thermal expansion characteristics match that of the heater wire 1. Suitable insulating materials are alumina, a mixture of boron nitride and alumina, a mixture of magnesium oxide and boron nitride, and a mixture of magnesium oxide and alumina.
- a mixture of alumina and boron nitride powder provides an insulating material having thermal expansion characteristics which matches that of molybdenum.
- the selected material is deposited on the formed wire by flame spraying, chemical vapor deposition, or cataphoresis.
- overcoating 4 is likewise selected so that its thermal expansion characteristic matches that of both wire 1 and insulating coating 3.
- Metals found suitable for forming such overcoating are molybdenum, tungsten, and nickel.
- the overcoating may likewise be applied by any suitable method such as flame spraying, chemical vapor deposition, or cataphoresis. Again, tungsten or molybdenum oxides may be used for overcoating 4 then converted to the pure metal by heating in a reducing atmosphere.
- Powder 5 may comprise molybdenum, nickel, or a mixture of molybdenum and nickel powders depending on the metals of overcoat 4 and plate 6 and the brazing or alloying temperature is selected accordingly.
- an alloy of molybdenum and nickel will permit brazing a heater structure having an overcoating 4 of tungsten, molybdenum, or nickel to a tungsten, molybdenum, or nickel disc or plate 6 as the case may be, by hydrogen brazing at l,350 C.
- FIG. 3 shows a planar configuration in which the layer of turns of heater wire is not spiral but permits other configurations.
- the configuration shown is particularly suitable for use in domestic heating appliances, having a continuous surface or panel to which the heater is brazed or otherwise bonded, suitable terminals (not shown) being attached to the uncoated ends of wire 1.
- FIG. 4 shows the heater of my invention used in conjunction with a cathode for an electron discharge device.
- Cathode 8 comprises a tungsten disc having transverse slots 13 and is formed in the manner shown and described in my U.S. Pat. No. 3,334,263, granted Aug. 1, i967, and assigned to the assignee of this present invention.
- the structure of FIG. 4 also employs a backup disc 9 which may be desirable, in some instances, to maintain the cathode flat and further assist in preventing warping.
- the use of a backup disc 9 is particularly desirable in those instances where the heater and cathode structures are not made entirely of materials having similar thermal expansion characteristics.
- cathode 8 is of tungsten while heater wire 1 consists of molybdenum with an insulating material 3 of alumina and an overcoating of molybdenum, then it is desirable to use a tungsten backup disc 9.
- Disc 9 may be formed of the same metal as disc 8 and have openings 10 for receiving the terminal portions of the heater. lnterposed between one surface of disc 9 and the turns 2 of my heater is a metal layer 11 suitable for brazing to or alloying with disc 9 and the overcoating material 4 on the heater. Layer 11 may comprise, for example, a mixture of nickel and molybdenum powders which is coated on the overcoating metal 4 at the same time that metal layer 5 is placed between the other surface of the heater and cathode 8. The entire assembly is then hydrogen brazed at a suitable temperature, for
- the disc 9 may be, for example, a very thin tungsten disc having a thickness of the order of 0.010 inch.
- a tungsten cathode 8 employing my bonded heater construction has been found to remain flat after many repeated heating and cooling cycles. Such a structure is particularly desirable for microwave electron tubes in which very close spacing is desired between the cathode structure and any grid of the discharge device.
- the cathode disc 8 comprises a porous tungsten member.
- Wire 1 is molybdenum wire.
- Insulating coating 3 is a mixture of boron nitride and alumina and overcoating 4 is a layer of molybdenum which is applied by flame spraying.
- the brazed metal layers 5 and 11 comprise a molybdenum nickel alloy having a melting temperature of approximately 1,3 l 5 C.
- Backup disc 9 comprises a l0-mil tungsten disc.
- backup disc 9 is needed only if the heater and the surface 6 to which it is brazed do not I have perfectly matched thermal expansion characteristics.
- the heater can be repeatedly cycled to red-hot temperatures without causing separation of the heater from the object being heated.
- An electrical heater comprising coplanar turns of a heater wire, input terminals for said wire, the metal of the wire being selected from the group consisting of molybdenum and tungsten; a coating of insulating material surrounding said wire, said insulating material being selected from a group consisting of alumina, a mixture of boron nitride and alumina, and a mixture of boron nitride and magnesium oxide; a metal overcoating surrounding the insulating material, the metal of said overcoating being selected from the group consisting of molybdenum and tungsten; a layer of metal attached to at least one side of said overcoated wire, the metal of said layer consisting of molybdenum or an alloy of molybdenum and nickel; the proportions of said insulating materials and the materials of said wire, overcoating metal, and metal layer all being selected to have closely matched thermal expansion characteristics over a wide range of temperatures; and a metal object to be heated having a flat surface parallel with and integrally attached to said
- the heater wire and overcoating consist of molybdenum
- the metal layer is an alloy of molybdenum and nickel
- the insulating material is alumina
- the heater of claim 1 in which the heater wire and overcoating consist of tungsten, the metal layer is an alloy of molybdenum and nickel, and the insulating material is boron nitride.
- the heater of claim 1 in which the metal of said object is selected from the group consisting of molybdenum, tungsten and nickel.
- Alumina plus boron nitride d0 d0 Do. Tungsten... Boron nitride Tungsten do Tungsten Do Alumina plus boron nitride do D Molybdenum Alumina Molybdenum D0. Nickel Alumina plus magnesia- Nickel .do Nickel.
Landscapes
- Resistance Heating (AREA)
- Solid Thermionic Cathode (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US81106769A | 1969-03-27 | 1969-03-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3581144A true US3581144A (en) | 1971-05-25 |
Family
ID=25205459
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US811067A Expired - Lifetime US3581144A (en) | 1969-03-27 | 1969-03-27 | Metal-clad insulated electrical heater |
Country Status (6)
Country | Link |
---|---|
US (1) | US3581144A (de) |
JP (1) | JPS5034769B1 (de) |
DE (1) | DE2011215C3 (de) |
FR (1) | FR2040031A5 (de) |
GB (1) | GB1283143A (de) |
NL (1) | NL7002986A (de) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3686477A (en) * | 1971-08-06 | 1972-08-22 | Gen Electric | Mounting system for solid plate surface heating units |
US3725641A (en) * | 1971-08-13 | 1973-04-03 | Adams Ind | Electric cup heater |
WO1997043873A1 (en) * | 1996-05-15 | 1997-11-20 | Strix Limited | Electric heaters |
US20110162391A1 (en) * | 2008-07-01 | 2011-07-07 | Ball-Difazio Doreen J | Method and Apparatus for Providing Temperature Control to a Cryopump |
US20120177837A1 (en) * | 2007-08-10 | 2012-07-12 | Eckert C Edward | Metallophobic thermally applied ceramic materials |
US20140141172A1 (en) * | 2007-08-10 | 2014-05-22 | C. Edward Eckert | Metallophobic thermally applied ceramic materials |
US20150063791A1 (en) * | 2012-03-12 | 2015-03-05 | T.P.A. Impex S.P.A. | Boiler for Domestic Appliances and Water Heating Systems With Steam Production for Home and Industrial Use |
US10634415B2 (en) | 2018-05-01 | 2020-04-28 | Haier Us Appliance Solutions, Inc. | Refrigerator appliance and arc-resistant heating assembly |
CN113808892A (zh) * | 2021-09-22 | 2021-12-17 | 中国科学院空天信息创新研究院 | 复合热子组件及其制备方法 |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1979000924A1 (en) * | 1978-04-12 | 1979-11-15 | Matsushita Electric Ind Co Ltd | Tubular heating element |
FR2730119B1 (fr) * | 1995-02-01 | 1997-03-28 | Seb Sa | Ensemble chauffant electrique |
KR19980701703A (ko) * | 1995-02-01 | 1998-06-25 | 폴 리비에르 | 방열판을 구비한 가열 요소와 그 조립 방법 |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1975870A (en) * | 1933-07-07 | 1934-10-09 | Rca Corp | Indirectly heated cathode |
US2075910A (en) * | 1926-07-07 | 1937-04-06 | Ass Elect Ind | Thermionic cathode |
US2131909A (en) * | 1934-11-30 | 1938-10-04 | Rca Corp | Alloy |
US2504335A (en) * | 1946-08-30 | 1950-04-18 | Hartford Nat Bank & Trust Co | Indirectly heated cathode |
US3117249A (en) * | 1960-02-16 | 1964-01-07 | Sperry Rand Corp | Embedded heater cathode |
US3221203A (en) * | 1962-06-01 | 1965-11-30 | Rca Corp | Sintered metal conductor support |
US3400294A (en) * | 1964-12-07 | 1968-09-03 | Gen Electric | Heated cathode and method of manufacture |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1004776A (en) * | 1961-03-15 | 1965-09-15 | Gen Electric | Improvements in cathode construction |
NL281567A (de) * | 1962-07-30 | |||
NL6512348A (de) * | 1965-09-23 | 1967-03-28 |
-
1969
- 1969-03-27 US US811067A patent/US3581144A/en not_active Expired - Lifetime
-
1970
- 1970-02-19 GB GB7963/70A patent/GB1283143A/en not_active Expired
- 1970-03-03 NL NL7002986A patent/NL7002986A/xx unknown
- 1970-03-10 DE DE2011215A patent/DE2011215C3/de not_active Expired
- 1970-03-26 JP JP45024944A patent/JPS5034769B1/ja active Pending
- 1970-03-26 FR FR7010927A patent/FR2040031A5/fr not_active Expired
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2075910A (en) * | 1926-07-07 | 1937-04-06 | Ass Elect Ind | Thermionic cathode |
US1975870A (en) * | 1933-07-07 | 1934-10-09 | Rca Corp | Indirectly heated cathode |
US2131909A (en) * | 1934-11-30 | 1938-10-04 | Rca Corp | Alloy |
US2504335A (en) * | 1946-08-30 | 1950-04-18 | Hartford Nat Bank & Trust Co | Indirectly heated cathode |
US3117249A (en) * | 1960-02-16 | 1964-01-07 | Sperry Rand Corp | Embedded heater cathode |
US3221203A (en) * | 1962-06-01 | 1965-11-30 | Rca Corp | Sintered metal conductor support |
US3400294A (en) * | 1964-12-07 | 1968-09-03 | Gen Electric | Heated cathode and method of manufacture |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3686477A (en) * | 1971-08-06 | 1972-08-22 | Gen Electric | Mounting system for solid plate surface heating units |
US3725641A (en) * | 1971-08-13 | 1973-04-03 | Adams Ind | Electric cup heater |
WO1997043873A1 (en) * | 1996-05-15 | 1997-11-20 | Strix Limited | Electric heaters |
GB2332845A (en) * | 1996-05-15 | 1999-06-30 | Strix Ltd | Electric heaters |
GB2332845B (en) * | 1996-05-15 | 2000-10-04 | Strix Ltd | Electric heaters |
US20120177837A1 (en) * | 2007-08-10 | 2012-07-12 | Eckert C Edward | Metallophobic thermally applied ceramic materials |
US20140141172A1 (en) * | 2007-08-10 | 2014-05-22 | C. Edward Eckert | Metallophobic thermally applied ceramic materials |
US20110162391A1 (en) * | 2008-07-01 | 2011-07-07 | Ball-Difazio Doreen J | Method and Apparatus for Providing Temperature Control to a Cryopump |
US20150063791A1 (en) * | 2012-03-12 | 2015-03-05 | T.P.A. Impex S.P.A. | Boiler for Domestic Appliances and Water Heating Systems With Steam Production for Home and Industrial Use |
US9702544B2 (en) * | 2012-03-12 | 2017-07-11 | T.P.A. Impex S.P.A. | Boiler for domestic appliances and water heating systems with steam production for home and industrial use |
US10634415B2 (en) | 2018-05-01 | 2020-04-28 | Haier Us Appliance Solutions, Inc. | Refrigerator appliance and arc-resistant heating assembly |
CN113808892A (zh) * | 2021-09-22 | 2021-12-17 | 中国科学院空天信息创新研究院 | 复合热子组件及其制备方法 |
CN113808892B (zh) * | 2021-09-22 | 2023-10-20 | 中国科学院空天信息创新研究院 | 复合热子组件及其制备方法 |
Also Published As
Publication number | Publication date |
---|---|
DE2011215C3 (de) | 1981-11-05 |
JPS5034769B1 (de) | 1975-11-11 |
NL7002986A (de) | 1970-09-29 |
DE2011215A1 (de) | 1970-10-08 |
DE2011215B2 (de) | 1980-11-20 |
GB1283143A (en) | 1972-07-26 |
FR2040031A5 (de) | 1971-01-15 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: INDIANA NATIONAL BANK, THE,INDIANA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MPD, INC.;REEL/FRAME:004666/0835 Effective date: 19861231 Owner name: INDIANA NATIONAL BANK, THE, ONE INDIANA SQUARE, IN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:MPD, INC.;REEL/FRAME:004666/0835 Effective date: 19861231 |