[go: up one dir, main page]

US2961628A - Infrared radiation heating elements - Google Patents

Infrared radiation heating elements Download PDF

Info

Publication number
US2961628A
US2961628A US767130A US76713058A US2961628A US 2961628 A US2961628 A US 2961628A US 767130 A US767130 A US 767130A US 76713058 A US76713058 A US 76713058A US 2961628 A US2961628 A US 2961628A
Authority
US
United States
Prior art keywords
infrared radiation
wall
alumina
tube
heating elements
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
Application number
US767130A
Inventor
Aigrain Pierre
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
CSF Compagnie Generale de Telegraphie sans Fil SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by CSF Compagnie Generale de Telegraphie sans Fil SA filed Critical CSF Compagnie Generale de Telegraphie sans Fil SA
Application granted granted Critical
Publication of US2961628A publication Critical patent/US2961628A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B33/00—Clay-wares
    • C04B33/02—Preparing or treating the raw materials individually or as batches
    • C04B33/025—Mixtures of materials with different sizes
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B33/00—Clay-wares
    • C04B33/02—Preparing or treating the raw materials individually or as batches
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/025—Other inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/08—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances quartz; glass; glass wool; slag wool; vitreous enamels
    • 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
    • H05B3/44—Heating elements having the shape of rods or tubes non-flexible heating conductor arranged within rods or tubes of insulating material

Definitions

  • the present invention relates to infrared heating elements of the type comprising a radiating element combined with a wall having a shape corresponding to that of the element and through which the radiation takes place.
  • This wall must of course be such as to absorb as little infrared radiation energy as possible. It is generally made of silicon.
  • the infrared heating element comprises a wall, shaped as a tube, plate or otherwise, of ceramic material, preferably of alumine, the grains of which are sufiiciently fine for said element to operate in Lord Rayleighs diffusion without absorption zone.
  • the alumina is prepared in such a manner that the size of the elementary crystallites forming the wall is smaller than .1 or even .01 micron, the alumina being preferably obtained from a gamma-type aluminum powder, sintered at a temperature lower than 1200 C. so as to avoid an excessive increase in size of the grains.
  • the alumina wall is enamelled.
  • heating device of the invention relating, respectively, to a tube and to a plate of finely grained alumina.
  • Example 1 A tube-shaped wall 1 is provided for housing a heating metallic resistance 2, the operating temperature of which is of the order of 1,000 C.
  • Tube 1 is manufactured from a gamma-type alumina powder, the mean grain size of which is approximately .02 to .03 micron.
  • This powder is mixed with any suitable binder, such as, for instance, a mixture of terpine oil and ceresine, and is then extruded to provide a tubular element.
  • any suitable binder such as, for instance, a mixture of terpine oil and ceresine
  • the gamma-alumina changes into alpha-alumina.
  • the fired tube has a diameter of the order of 15 mm., a wall thickness of about 1 mm. and a length of approximately 500 mm.
  • the tube is then sprayed, for example, by means of a pneumatic gun, with an aqueous solution containing an enamel powder which may, for example, comprise:
  • Percent Pb At least 40 SiO At least 20 BrO About 10 SnO and A1 About 20
  • the resulting tube is robust and its mechanical strength is improved by the enamel treatment which in addition renders the tube impervious to gases and vapors so that it may also be employed in an explosive atmosphere.
  • the tube is transparent to infrared rays, on account of its fine grained structure and the enamel does not impair said transparency. Also owing to the enamel treatment the tube is adapted for protracted storing or resting in a humid atmosphere without absorbing water and consequently without any risk of bursting when put in operation.
  • the wall is a plate adapted to be placed in front of an infrared energy source comprising a refractory plate of porous ceramic formed with holes, at the surface of which gas combustion takes place.
  • an infrared energy source comprising a refractory plate of porous ceramic formed with holes, at the surface of which gas combustion takes place.
  • Such a source is commonly known as an infrared radiant panel.
  • the presence of the wall isolates the flame from the ambient air and insures the safety of the system while preventing the projection of particles into the air.
  • the wall according to the invention is obtained by pressing a mixture of the gamma aluminum powder previously described with a suitable binder, which may be, for instance, a polyvinyl alcohol. After sintering, which is effected at a temperature of between 1,100 and 1,200 C., a rectangular plate of 10 by 20 cm. with a few millimeters thickness is obtained. This plate, which is, preferably, enamelled as in Example 1, is secured in the front of the radiant panel by conventional means.
  • a suitable binder which may be, for instance, a polyvinyl alcohol.
  • the manufacturing process is based on known techniques enabling the production of finely grained elements. There are many variations of such techniques. However they differ notably from the more usual techniques for the manufacturing of industrial coarse grained alumina wherein sintering is effected at much higher temperatures.
  • a common coarse grained alumina would absorb a substantial portion of the heat emitted by the radiant filament, thereby substantially increasing the temperature thereof. An important loss of heat by convection would result, with a consequent prohibitory decrease of the radiated energy.
  • ultra fine grained alumina constitutes the substance which is preferred for the manufacture of walls according to the invention
  • any inorganic powder capable of agglomerating by sintering in fine grained state to form crystallites of less than .1 micron may also be used. This is particularly the case with titanium oxide.
  • a heating element comprising an infrared radiation emitting source and a wall transparent to said infrared radiation, said Wall consisting of sintered alumina, the grain size of which is smaller than .1 micron.
  • a heating element comprising an enamelled tube and an electrically resistant body contained in said tube, said tube being of gamma type alumina sintered at a temperature lower than 1,200 0., the grain size of which is smaller than .1 micron.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Resistance Heating (AREA)

Description

Nov. 22, 1960 P. AlGRAlN INFRARED RADIATION HEATING ELEMENTS Filed Oct. 14, 1958 2,961,628 Patented Nov. 22, 1960 2,961,628 INFRARED RADIATION HEATING ELEMENTS Pierre Aigrain, Paris, France, assiguor to Compagnie Generale de Telegraphie Sans Fil, a corporation of France Filed Oct. 14, 1958, Ser. No. 767,130 Claims priority, application France Oct. 18, 1957 2 Claims. (Cl. 338-269) The present invention relates to infrared heating elements of the type comprising a radiating element combined with a wall having a shape corresponding to that of the element and through which the radiation takes place. This wall must of course be such as to absorb as little infrared radiation energy as possible. It is generally made of silicon.
It is an object of the invention to provide an infraredradiation heating element of improved design and higher efiiciency.
The infrared heating element according to the invention, comprises a wall, shaped as a tube, plate or otherwise, of ceramic material, preferably of alumine, the grains of which are sufiiciently fine for said element to operate in Lord Rayleighs diffusion without absorption zone.
Preferably, the alumina is prepared in such a manner that the size of the elementary crystallites forming the wall is smaller than .1 or even .01 micron, the alumina being preferably obtained from a gamma-type aluminum powder, sintered at a temperature lower than 1200 C. so as to avoid an excessive increase in size of the grains.
According to a preferred embodiment of the invention the alumina wall is enamelled.
The invention will be better understood from the following non-limitative examples of heating device of the invention relating, respectively, to a tube and to a plate of finely grained alumina.
In the appended drawing, the single figure shows a tubular heating device according to the invention.
Example 1 A tube-shaped wall 1 is provided for housing a heating metallic resistance 2, the operating temperature of which is of the order of 1,000 C. Tube 1 is manufactured from a gamma-type alumina powder, the mean grain size of which is approximately .02 to .03 micron.
This powder is mixed with any suitable binder, such as, for instance, a mixture of terpine oil and ceresine, and is then extruded to provide a tubular element. In the course of sintering, which is effected at a temperature comprised between 1,100 and 1,200 C., the gamma-alumina changes into alpha-alumina. The fired tube has a diameter of the order of 15 mm., a wall thickness of about 1 mm. and a length of approximately 500 mm. The tube is then sprayed, for example, by means of a pneumatic gun, with an aqueous solution containing an enamel powder which may, for example, comprise:
Percent Pb At least 40 SiO At least 20 BrO About 10 SnO and A1 About 20 The resulting tube is robust and its mechanical strength is improved by the enamel treatment which in addition renders the tube impervious to gases and vapors so that it may also be employed in an explosive atmosphere.
The tube is transparent to infrared rays, on account of its fine grained structure and the enamel does not impair said transparency. Also owing to the enamel treatment the tube is adapted for protracted storing or resting in a humid atmosphere without absorbing water and consequently without any risk of bursting when put in operation.
Example 2 In this example, the wall is a plate adapted to be placed in front of an infrared energy source comprising a refractory plate of porous ceramic formed with holes, at the surface of which gas combustion takes place. Such a source is commonly known as an infrared radiant panel. The presence of the wall isolates the flame from the ambient air and insures the safety of the system while preventing the projection of particles into the air.
The wall according to the invention is obtained by pressing a mixture of the gamma aluminum powder previously described with a suitable binder, which may be, for instance, a polyvinyl alcohol. After sintering, which is effected at a temperature of between 1,100 and 1,200 C., a rectangular plate of 10 by 20 cm. with a few millimeters thickness is obtained. This plate, which is, preferably, enamelled as in Example 1, is secured in the front of the radiant panel by conventional means.
It is to be understood that above examples are only illustrative of the invention and many variations and modifications may be effected without departing from the scope thereof: in particular, alumina envelopes of different shapes and dimensions may be realized.
The manufacturing process, as described briefly hereinabove, is based on known techniques enabling the production of finely grained elements. There are many variations of such techniques. However they differ notably from the more usual techniques for the manufacturing of industrial coarse grained alumina wherein sintering is effected at much higher temperatures.
A common coarse grained alumina would absorb a substantial portion of the heat emitted by the radiant filament, thereby substantially increasing the temperature thereof. An important loss of heat by convection would result, with a consequent prohibitory decrease of the radiated energy.
Although the ultra fine grained alumina constitutes the substance which is preferred for the manufacture of walls according to the invention, any inorganic powder capable of agglomerating by sintering in fine grained state to form crystallites of less than .1 micron may also be used. This is particularly the case with titanium oxide.
What is claimed is:
l. A heating element comprising an infrared radiation emitting source and a wall transparent to said infrared radiation, said Wall consisting of sintered alumina, the grain size of which is smaller than .1 micron.
2. A heating element comprising an enamelled tube and an electrically resistant body contained in said tube, said tube being of gamma type alumina sintered at a temperature lower than 1,200 0., the grain size of which is smaller than .1 micron.
References Cited in the file of this patent UNITED STATES PATENTS 1,705,300 Maxson Mar. 12, 1929 2,092,815 Shaw Sept. 14, 1937 2,372,212 Lewin Mar. 27, 1945 2,714,096 Suchet July 26, 1955

Claims (1)

1. A HEATING ELEMENT COMPRISING AN INFRARED RADIATION EMITTING SOURCE AND A WALL TRANSPARENT TO SAID INFRARED RADIATION, SAID WALL CONSISTING OF SINTERED ALUMINA, THE GRAIN SIZE OF WHICH IS SMALLER THAN .1 MICRON.
US767130A 1957-10-18 1958-10-14 Infrared radiation heating elements Expired - Lifetime US2961628A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR2961628X 1957-10-18
FR893724X 1957-10-18

Publications (1)

Publication Number Publication Date
US2961628A true US2961628A (en) 1960-11-22

Family

ID=26227784

Family Applications (1)

Application Number Title Priority Date Filing Date
US767130A Expired - Lifetime US2961628A (en) 1957-10-18 1958-10-14 Infrared radiation heating elements

Country Status (2)

Country Link
US (1) US2961628A (en)
DE (1) DE1107871B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0525458A1 (en) * 1991-07-13 1993-02-03 Braun Aktiengesellschaft Toaster heating device with isolating tube

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1705300A (en) * 1927-07-25 1929-03-12 Burdick Corp Therapeutic lamp
US2092815A (en) * 1935-11-23 1937-09-14 Rca Corp Cathode heater insulation
US2372212A (en) * 1942-03-03 1945-03-27 American Electro Metal Corp Electrical heating element
US2714096A (en) * 1952-03-31 1955-07-26 Csf Non-linear resistances

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1705300A (en) * 1927-07-25 1929-03-12 Burdick Corp Therapeutic lamp
US2092815A (en) * 1935-11-23 1937-09-14 Rca Corp Cathode heater insulation
US2372212A (en) * 1942-03-03 1945-03-27 American Electro Metal Corp Electrical heating element
US2714096A (en) * 1952-03-31 1955-07-26 Csf Non-linear resistances

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0525458A1 (en) * 1991-07-13 1993-02-03 Braun Aktiengesellschaft Toaster heating device with isolating tube

Also Published As

Publication number Publication date
DE1107871B (en) 1961-05-31

Similar Documents

Publication Publication Date Title
US3792136A (en) Method for preparing hollow metal oxide microsphere
GB1595518A (en) Polycrystalline alumina material
GB1245005A (en) Transparent spinel body
US3738793A (en) Illumination burner
GB1390572A (en) High-pressure gas discharge lamp
US2974388A (en) Process of making ceramic shells
US3087041A (en) Space heater
US2961628A (en) Infrared radiation heating elements
GB1105111A (en) Improvements in dental materials
US3834915A (en) Fine grain translucent alumina
GB1128146A (en) Infra-red radiation emitter
US2898496A (en) Electrically conductive films and method for producing same
US2244558A (en) Fluorescent material
JPH08298099A (en) Arc tube for metal vapor discharge lamp
US4064402A (en) Method and apparatus for suppressing the visible radiation emitted by a source of infra-red radiation
US3162030A (en) Permanent wick structure
US3310968A (en) Photoflash lamp
JPH05190142A (en) Electric bulb and manufacture thereof
US2418202A (en) Fluorescent lamp and method of manufacture
US2227418A (en) Electric lamp
CN104961466B (en) A kind of preparation method of the rare earth ion doped MgAlON transparent ceramic materials with ultraviolet filtration ability
US3365323A (en) Stabilized red pigment filter coating in a fluorescent lamp
GB1034122A (en) Improvements in or relating to electrical devices having envelopes formed at least in part of sintered polycrystalline alumina
GB893724A (en) Improvements in or relating to infra-red radiation heating elements
US3551719A (en) Arc lamp with concentric electrodes