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WO2004062319A1 - Monolithique self-regulating metal-ceramic heater - Google Patents

Monolithique self-regulating metal-ceramic heater Download PDF

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Publication number
WO2004062319A1
WO2004062319A1 PCT/BY2003/000001 BY0300001W WO2004062319A1 WO 2004062319 A1 WO2004062319 A1 WO 2004062319A1 BY 0300001 W BY0300001 W BY 0300001W WO 2004062319 A1 WO2004062319 A1 WO 2004062319A1
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Prior art keywords
layer
heating
heating element
heat
insulating layer
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Ceased
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English (en)
Inventor
Vladimir P. Lapin
Genadiy A. Govor
Alexandr L. Shitenkov
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Priority to AU2003201228A priority Critical patent/AU2003201228A1/en
Priority to PCT/BY2003/000001 priority patent/WO2004062319A1/fr
Publication of WO2004062319A1 publication Critical patent/WO2004062319A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/03—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite
    • C04B35/04—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite based on magnesium oxide
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/16—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay
    • C04B35/20—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay rich in magnesium oxide, e.g. forsterite
    • 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
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • 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
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • H05B3/141—Conductive ceramics, e.g. metal oxides, metal carbides, barium titanate, ferrites, zirconia, vitrous compounds
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/36—Glass starting materials for making ceramics, e.g. silica glass
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/36—Glass starting materials for making ceramics, e.g. silica glass
    • C04B2235/365—Borosilicate glass
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/38—Non-oxide ceramic constituents or additives
    • C04B2235/3852—Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
    • C04B2235/386—Boron nitrides
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/72—Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/78—Grain sizes and shapes, product microstructures, e.g. acicular grains, equiaxed grains, platelet-structures
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/78—Grain sizes and shapes, product microstructures, e.g. acicular grains, equiaxed grains, platelet-structures
    • C04B2235/782—Grain size distributions
    • C04B2235/783—Bimodal, multi-modal or multi-fractional
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/78—Grain sizes and shapes, product microstructures, e.g. acicular grains, equiaxed grains, platelet-structures
    • C04B2235/786—Micrometer sized grains, i.e. from 1 to 100 micron
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • 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
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/02—Heaters using heating elements having a positive temperature coefficient

Definitions

  • the invention relates to the field of electric heating and of resistive heating in particular, and namely to monolithic self-regulating metal-ceramic heating elements intended for use in various electric heating devices both for industrial and household purposes. It also includes the method of manufacturing thereof
  • the dependability of a heating element is defined by the characteristics of a heating body.
  • a heating body made of metal which can be subject to oxidation, is characterized by lesser dependability as compared to ceramic or composite materials, where the oxidation processes are not observed at all or are observed in much lesser degree.
  • Ceramic heating elements for various purposes are offered in references [US5948306, dd. 07.09.1999; US6025579, dd. 15.02.2000; US6143238, dd. 07.11.2000].
  • the operating dependability of a heating element is largely influenced by the temperature dependence of the specific resistance of a heating body.
  • the positive temperature coefficient (PTC- characteristic) makes it possible to eliminate spontaneous heating of the element and consequently its failure [see, for example, US6350969, dd. 26.02.2002].
  • the uniform temperature distribution on the heating element surface and the expansion isotropy under heating are determined by the form and symmetry of the heating body structure. Partly the symmetry of the heating body on the dependability of the heating element was considered in the US patent No. US4596922, dd. 24.06.1986].
  • the cost of a heating element is of no less importance, said cost being defined by the cost of components for heating, insulating and other bodies and the technology of manufacturing thereof. The latter excludes the use of rare-earth oxides and other costly components.
  • the aim set forth is achieved in a heating element containing a heating resistive PTC body placed in an insulating layer by means of making said heating resistive body of Fe-based composite material having the specific resistance increasing with the temperature rising in the range from 100 to 200 ⁇ Ohm.m.
  • the net surface of the heating resistive body makes up from 40 to 60% of the heating element total area.
  • a heating resistive body is made in the shape of an irregular path having the width of d, said path being comprised of linear sections having the maximum length of lOd, said sections being sequentially connected by rounded-off sections, while the symmetry axes of the heating resistive body coincides with the symmetry axes of a heating element, and said irregular path of the heating resistive body is located inside an insulating layer, which follows its shape.
  • a heating element is additionally supplied with a Fe powder-based protective layer having the thickness of 0,5- Id, said protective layer being shaped such that to capsulate of the insulating layer on the three sides, said insulating layer comprising therein the heating resistive body.
  • An electric-insulating layer is preferably made of MgO-based glass ceramics with the following ratio of components, % by weight:
  • the magnesium oxide in the above-said ceramics has the following composition, % by weight:
  • a heating element is additionally supplied with a heat-insulating layer, which layer is preferably made of MgO-based glass ceramics with the following ratio of components, % by weight:
  • the layer of heat-insulating glass ceramics is covered by at least one layer of the heat- insulating paste, e.g. on base of the Fire Sealant 1200.
  • the layer of heat-insulating glass ceramics and the layer of heat-insulating paste taken together are impregnated with high-temperature waterproofing silicon liquid.
  • the aim set forth in a method of manufacturing of a heating element comprising the steps of making a heating resistive body, forming around said heating resistive body of an insulating layer, further compacting and sintering of the heating element, is achieved by means of that prior to sintering at least one additional layer is applied on the pre-defined portions of the insulating layer thus formed with subsequent additional pre-pressing following the application of each layer, while sintering is provided after compression of a multi-layer structure thus received.
  • a heating resistive body is made of Fe-based composite material having the specific resistance increasing with the temperature rising in the range from 100 to 200 . ⁇ Ohm.m.
  • An electric insulating layer is made of MgO- based glass ceramics with the following ratio of components, % by weight:
  • the magnesium oxide in the above-said glass ceramics has the following ratio of components, % by weight:
  • MgO having the dispersion from 40 to 150 ⁇ k - 45-55% MgO having maximum dispersion of 40 ⁇ k - 45-55%.
  • a protective Fe-powder layer is placed in such a way that it covers an insulating layer on the three sides.
  • a heat-insulating layer of MgO-based glass ceramics is placed on the surface of the multi-layer structure thus received which is free from protective layer, said heat- insulating layer having the following ratio of components, % by weight:
  • Compacting of a multi-layer structure of a heating element is provided in the pressure range from 3 to 4 kbar. Sintering of a multi-layer structure is carried out on the air with the time exposure period from 0,5 to two hours in the temperature range from 900 to 1150°C.
  • a heat-insulating layer is covered by at least one layer of heat-insulating paste, e.g. on base of Fire Sealant- 1200, and all these taken together are impregnated with a high temperature waterproofing silicon liquid.
  • Fig. 1 shows a schematic cross-sectional view of a heating element.
  • Fig.2 shows the temperature dependence of the specific resistance of the conductive body.
  • Fig.3 shows a schematic view of the heat transfer in a flat heating element.
  • Fig. 4 shows the heat distribution in a heat-absorbing surface Sa for various ratios of the radiant and heat-absorbing surfaces at different widths of a damping layer.
  • Fig.5 shows an example of a conductive body for a circular-shaped heating element.
  • Fig.6 shows a method of manufacturing of a heating element in accordance with the present invention in its diagrammatic form.
  • An electric heating element in accordance with the present invention is manufactured according to powder metallurgy technique and presents in itself a multi-layer structure comprising accordingly a metal-ceramic heating resistive body, an electric and heat insulating glass ceramic layers, a protective metal layer, all these taken together having been compacted and sintered to form a monolithic structure.
  • Fig.1 shows a schematic cross-sectional view of a heating element in accordance with the present invention embodying the latter in the form of a flat heating element.
  • the basic constituent part of a heating element in accordance with the present invention is a metal-ceramic heating resistive body 1 capsulated by an electric insulating layer 2 which follows the shape of said heating resistive body 1.
  • a protective Fe powder layer 3 is shaped such that to capsulate the insulating layer 2 on the three sides.
  • a heat- insulating layer 4 is made in the form of a heat-insulating glass ceramic layer 5 with a heat-insulating paste layer 6.
  • a decorative ceramic layer 7 is applied above the protective metallic layer 3.
  • a metal-ceramic heating resistive body 1 is made of Fe-based composite material having the specific resistance increasing from 100 to 200 ⁇ Olim.m with the temperature rising from 0 to 1000°C.
  • a temperature dependence of the specific resistance of the metal-ceramic heating • resistive body 1 is shown in Fig.2.
  • the specific resistance of the metal-ceramic is by two to three orders higher than the specific resistance of the metal conductors known in the art while preserving the PTC-characteristic.
  • the metal-ceramic heating resistive body 1 of the type described may be made of Fe-based composite material wherein each Fe particle is covered by a thin dielectric layer, e.g. SMC-500 of H ⁇ ganas AB Co. (Sweden).
  • the temperature dependence pecularity of the specific resistance of the metal-ceramic heating resistive body 1 consists in providing the heating of said body 1 within only a few seconds. Besides, high specific resistance makes it possible to considerably diminish the overall dimensions of the heating elements.
  • the net surface of the metal-ceramic heating resistive body of a heating element in accordance with the present invention makes up from 40 to 60%) of the total area of the heating element.
  • F is the net surface of a heating resistive body 1 ;
  • ⁇ i + ⁇ ⁇ ] ⁇ ⁇ l and ⁇ 2 are respectively heat conductivity values of a glass ceramic insulating layer 2 and of a protective metal layer 3, ⁇ l and ⁇ 2 present the width values of the glass ceramic insulating layer 2 and of the metal layer 3 accordingly.
  • the maximum value of the heat transfer coefficient is defined by the proper heat conductivity of insulating glass ceramics ⁇ i containing according to the present invention the magnesium oxide and the boron nitride:
  • C M go and CN B are respectively the concentrations of the magnesium oxide and the boron nitride, while ⁇ i igo and B are accordingly their heat conductivity values.
  • the maximum value of heat transfer is defined by the net surface of a heating resistive body. Further there comes the description of the influence of the radiant and heat-absorbing surfaces ratio on the critical parameters of a heating element such as efficiency, the temperature of a radiant surface etc.
  • a heating resistive body 1 of a heating element comprised of m parallel flat conductors 8 of infinite length, having the width of d each, said conductors separated by insulation gaps 9 having the width of li.
  • a radiant surface Sr (which coincides with the surface of the heating resistive body 1) and a heat absorbing surface Sa are separated by a damping protective metallic layer 3 having the width of ⁇ 2 and heat conductivity of ⁇ 2 , said damping layer providing on the one hand the temperature smoothing in a heat-absorbing surface and on the other hand the insulation and protection of said heat-absorbing surface.
  • each flat conductor 8 is considered as being comprised of n linear sources 10 of infinite length.
  • q ij - (tr -ta) (6), ⁇ 2 where tr - ta is the temperature difference between the radiant surface Sr and the heat-absorbing surface Sa.
  • the decrease of the thickness of the damping layer and, hence,- of the weight of a heating element results in the decrease of initial heating time of the heating element up to several seconds and finally leads to the cost decrease of the heating element on the whole.
  • Rapid initial heating of an element in accordance with the present invention imposes certain requirements to its structure. Should a heating resistive body 1 be fed with a supply voltage, the current through it will cause its heating. The temperature increase causes the resistance increase of the heating resistive body 1 (See Fig. 2), while the current flowing through it is decreased with the resulting temperature stabilization at the pre-set level. Since the temperature of the heating resistive body 1 is changed within the fractions of a second, this process can be considered as an adiabatic one not causing any heat- exchange with a protective metal layer 3. The initial heating of the latter is provided within few seconds.
  • Extra-rapid initial heating of a conductive body leads to non-uniform mechanical tensions of a heating element and, hence, to its possible hogging. To eliminate hogging and to preserve the integrity of a heating element and, hence, its dependability the expansion uniformity of the latter should be provided.
  • the expansion isotropy is achieved by making the heating resistive body 1 in the shape of an irregular path having the width of d, said path being comprised of linear sections having the maximum length of lOd, said sections being sequentially connected by rounded-off sections, while the symmetry axes of the heating resistive body 1 coincide with the symmetry axes of a heating element, and said irregular path of the heating resistive body 1 is positioned inside an insulating layer 2, which follows its shape.
  • Fig. 5 shows an example of making a heating resistive body for the case of a circular- shaped heating element.
  • the heating resistive body 1 is made in the shape of an irregular path having the width of d, said path being comprised of linear sections 11 having the maximum length of lOd, said sections being sequentially connected by rounded-off sections 12. It is obvious from Fig. 5 that the heating resistive body 1 in the example shown has a symmetry axis of the 6-th order. The uniformity of adiabatic expansion of the heating resistive body 1 is provided by high symmetry extent as well as by positioning the linear sections 11 both along the radii and parallel to the circumferences of the respective radii. To provide reliable operation of a monolithic heating element in accordance with the present invention in its finished form after sintering, the latter is to have coherent thermal expansion coefficients of all its layers, i.e. a heating resistive body 1, an insulating layer 2, a protective metal layer 3 and a heat-insulating layer 4.
  • a protective metal layer 3 is Fe powder-based with anticorrosive additions.
  • thermal expansion coefficients are provided by means of the choice of appropriate glass ceramic components and their weight ratio.
  • an electric insulating glass ceramic layer 2 having the density which approximates an apparent one is made on periclase-base (the crystalline magnesium oxide) with the addition of the hexagonal boron nitride and alkali-free glass to increase heat-conductivity and specific resistance, in the following ratio:
  • the magnesium oxide in above-said glass ceramics has the following composition, % by weight: MgO having the dispersion from 40 to 150 ⁇ k - 45-55% MgO having maximum dispersion of 40 ⁇ k - 45-55%).
  • a heat-insulating layer 4 contains the layer 5 which is made of MgO-based glass ceramics having the following ratio of components, % by weight:
  • the above-said heat-insulating layer 5 is covered with at least one layer 6 of heat- insulating paste, e.g. on base Fire Sealant-1200.
  • the layer 5 of heat-insulating glass ceramics and the layer 6 of heat-insulating paste together are impregnated with a high temperature waterproofing silicon liquid.
  • EXAMPLE 1 Manufacturing of a flat circular-shaped heating element having the power of 600 W and an outer diameter of 125 mm.
  • a composite material having the specific resistance increasing in the range from 100 to 200 ⁇ Ohm.m with a temperature increase up to 1000°C e.g. a Fe-based composite material, wherein each Fe particle was covered by a thin dielectric layer, e.g. SMC-500 of H ⁇ ganas AB Co. (Sweden), was used in the form of the powder added with polyvinylacetate dispersion (PVA), 5% by weight.
  • PVA polyvinylacetate dispersion
  • a mold 13 for making a heating resistive body shown in Fig.5 was filled with 5 grams of said powder, and pre-compacting of the heating resistive body was carried out at the specific pressure of 0,3 kbar (Fig. 6a).
  • a blank of the heating resistive body 1 thus received was extracted from the mold 13 so that it turned out to be on the surface of said mold (Fig. 6b).
  • a face-mould 14 (Fig. 6c) was positioned above the mold 13, said face-mould having an internal cavity in the shape of an irregular path for making an insulating layer 2 following the shape of the heating resistive body 1.
  • the face-mould 14 was filled in full with 20 grams of electric isolation glass ceramic powder of the following composition: MgO 80%
  • Alkali-free glass 10% To provide the required density of electric isolation glass ceramics approximating an apparent one 11 grams of MgO having the dispersion from 40 to 150 ⁇ k and 9 grams of MgO having maximum dispersion of 40 ⁇ k were used.
  • Pre-pressing of insulating ceramic powder was carried out at the pressure of 0,3 kbar.
  • a mold 16 (Fig. 6e) was positioned, said mold being used for making an decorative coating of glass ceramic powder having the following composition: MgO 80%
  • the layer 7 of decorative coating having the thickness 0,2-0,3 mm provides metal protective layer from oxidizing during a sintering step.
  • Pre-pressing of multi-layers powder was carried out at the pressure of 0,3 kbar.
  • the mold 16 was turned upside-down, and on the bottom surface of a multi-layer blank thus received there was positioned a face-mould 17 (Fig. 6f) for making a heat- insulating coating.
  • the face-mould. 17 was filled with 20 grams of glass ceramic powder of the following composition: MgO 40%
  • Glass ceramic powder was added with 5% by weight of PVA.
  • the thickness of a heat-insulating layer 5 of a glass ceramic coating usually makes up from 0,6 to 0,8 mm.
  • a multi-layers powder structure thus received was compacted under normal conditions at the pressure of 4 kbar.
  • a compacted blank of a heating element was sintered in the air at the temperature of 1150°C with the exposure time of 0,5 hrs.
  • the sintering of a heating element was carried out with the eventual formation of its monolithic structure.
  • the weight of a heating element thus received made up 200 g.
  • EXAMPLE 2 Manufacturing of a square-shaped flat heating element having the power of 600 W.
  • a pre-generated mold 13 for making a heating resistive body 1 was filled with 3 grams of the powder as stated at the Example 1, and pre-compacting of the heating resistive body 1 was carried out at the specific pressure of 0,4 kbar (Fig. 6a).
  • a blank of the heating resistive body 1 thus received was extracted from the mold 13 so that it turned out to be on the surface of said mold (Fig. 6a).
  • a face-mould 14 (Fig. 6b) was positioned above the mold 13, said face-mould having an internal cavity in the shape of an irregular path for making an insulating layer 2 following the shape of the heating resistive body 1.
  • the face-mould 14 was filled in full 10 grams of with glass ceramic powder of the following composition:
  • Pre-pressing of glass ceramic powder was carried out at the pressure of 0,5 kbar.
  • the mold 16 was turned upside-down and on the bottom surface of a multi-layer blank thus received there was positioned a face-mould 17 (Fig. 6e) for making a heat- insulating coating.
  • the face-mould 17 was filled with 20 grams of glass ceramic powder of the following composition:
  • a compacted blank of a heating element was sintered in the air at the temperature of 1050°C with the exposure time of 1 hrs.
  • the layer 5 of the above-said heat-insulating glass ceramics was covered by one layer 6 of 10 grams of Fire Sealant 1200 heat-insulating paste.
  • the layer 5 of heat-insulating glass ceramics and the layer 6 of glass cloth taken together were impregnated with waterproofing high temperature silicon liquid.
  • the weight of a heating element thus received having the power of 600 W made up 150 g.
  • EXAMPLE 3 Manufacturing of a flat circular-shaped heating element having the power of 300 W.
  • a pre-generated mold 13 for making a heating resistive body 1 shown in Fig.5 was filled with 2 grams of the above-said powder, and pre-compacting of the heating resistive body 1 was carried out at the pressure of 0,4 kbar.
  • a blank of the heating resistive body 1 thus received was extracted from the mold 13 so that it turned out to be on the surface of said mold (Fig. 6a).
  • a face-mould 14 (Fig. 6b) was positioned above the mold 13, said face-mould having an internal cavity in the shape of an irregular path for making an insulating layer 2 following the shape of the heating resistive body 1.
  • the face-mould 14 was filled with 10 grams of electric isolation glass ceramic powder of the following composition: MgO 80%
  • Pre-pressing of glass ceramic powder was carried out at the pressure of 0,4 kbar.
  • the mold 16 was turned upside-down, and on the bottom surface of a multi-layer blank thus received there was positioned a face-mould 17 (Fig. 6e) for making a heat- insulating coating.
  • the face-mould 17 was filled with 20 grams of glass ceramic powder of the following composition:
  • Glass ceramic powder was added with 5% by weight of PVA.
  • a multi-layer powder structure thus received was compacted at room temperature with the pressure of 3 ,0 kbar.
  • a compacted blank of a heating element was sintered in the air at the temperature of 950°C with the exposure time of 1,5 hrs.
  • the sintering of a heating element was provided with the eventual formation of its monolithic structure.
  • the layer 5 of the above-said heat-insulating glass ceramics was covered by one layer 6 of 10 grams of Fire Sealant 1200 heat-insulating paste.
  • the weight of a heating element thus received having the power of 300 W made up 150 g.
  • the heating elements in accordance with the present invention can be manufactured in various shapes and of dimensions with the thickness of a heating element from 1mm and more.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Surface Heating Bodies (AREA)
  • Resistance Heating (AREA)

Abstract

L'invention concerne le domaine du chauffage électrique, en particulier, du chauffage résistais, et à savoir des éléments de chauffage métal-céramique monolithiques à autorégulation prévus pour être utilisés dans des dispositifs de chauffage électrique variés à la fois à des fins industrielles et à des fins domestiques. Un élément de chauffage contient un corps de chauffage (1) résistif à caractéristique de coefficient de température positive positionné dans une couche d'isolation électrique (2) Ledit corps de chauffage (1) résistif est composé d'un matériau composite à base de Fe dont la résistance spécifique augmente avec l'élévation de température dans une plage comprise entre 100 et 200 µOhm.m. Ce corps de chauffage (1) résistif est en forme de chemin irrégulier de largeur d, ledit chemin étant composé de sections linéaires (11) dont la longueur maximum est de 10d, ces sections étant séquentiellement connectée au moyen de sections rounded-off (12), les axes symétriques du corps de chauffage (1) résistif coïncidant avec les axes de symétrie d'un élément de chauffage. Le chemin irrégulier corps de chauffage résistif est positionné à l'intérieur de la couche d'isolation (2) qui épouse sa forme. L'invention concerne un procédé de fabrication d'un élément de chauffage consistant : à produire un chemin un corps de chauffage (1), à former autour de ce corps de chauffage (1) résistif une couche d'isolation électrique (2), et à presser et fritter l'élément de chauffage. Avant le frittage, on applique au moins une couche supplémentaire sur des parties prédéfinis de la couche d'isolation (2) ainsi formée à l'aide d'un pré-pressage supplémentaire subséquent après application sur chaque couche, le frittage étant effectué après compression de la structure multicouche ainsi reçue.
PCT/BY2003/000001 2003-01-02 2003-01-02 Monolithique self-regulating metal-ceramic heater Ceased WO2004062319A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU2003201228A AU2003201228A1 (en) 2003-01-02 2003-01-02 Monolithic self-regulating metal-ceramic heater
PCT/BY2003/000001 WO2004062319A1 (fr) 2003-01-02 2003-01-02 Monolithique self-regulating metal-ceramic heater

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/BY2003/000001 WO2004062319A1 (fr) 2003-01-02 2003-01-02 Monolithique self-regulating metal-ceramic heater

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WO2004062319A1 true WO2004062319A1 (fr) 2004-07-22

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101854750A (zh) * 2010-04-11 2010-10-06 青岛易特优电子有限公司 一种六方氮化硼及其混合导热材料的电热管
WO2012144740A3 (fr) * 2011-04-20 2013-01-03 (주)피엔유에코에너지 Cuisinière électrique possédant un élément chauffant autorégulateur de type feuille et procédé de fabrication associé
CN106793196A (zh) * 2016-11-28 2017-05-31 上海卫星装备研究所 一种高吸收率薄膜型电加热片
CN113142665A (zh) * 2021-04-20 2021-07-23 潘付强 用于电子烟的雾化部件烧结方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106231706A (zh) * 2016-09-05 2016-12-14 无锡富而凯奥克电气有限公司 双层绝缘结构的单端电加热元件

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5093555A (en) * 1988-07-22 1992-03-03 Beru Ruprecht Gmbh & Co. Kg Glow plug having cobalt/iron alloy regulating filament
EP0621738A2 (fr) * 1993-04-23 1994-10-26 E.G.O. Elektro-Geräte Blanc und Fischer GmbH & Co. KG Dispositif de sécurité pour un élément de chauffage électrique contre une réduction inadmissible du transfer de chaleur

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5093555A (en) * 1988-07-22 1992-03-03 Beru Ruprecht Gmbh & Co. Kg Glow plug having cobalt/iron alloy regulating filament
EP0621738A2 (fr) * 1993-04-23 1994-10-26 E.G.O. Elektro-Geräte Blanc und Fischer GmbH & Co. KG Dispositif de sécurité pour un élément de chauffage électrique contre une réduction inadmissible du transfer de chaleur

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101854750A (zh) * 2010-04-11 2010-10-06 青岛易特优电子有限公司 一种六方氮化硼及其混合导热材料的电热管
WO2012144740A3 (fr) * 2011-04-20 2013-01-03 (주)피엔유에코에너지 Cuisinière électrique possédant un élément chauffant autorégulateur de type feuille et procédé de fabrication associé
CN106793196A (zh) * 2016-11-28 2017-05-31 上海卫星装备研究所 一种高吸收率薄膜型电加热片
CN106793196B (zh) * 2016-11-28 2020-06-19 上海卫星装备研究所 一种高吸收率薄膜型电加热片
CN113142665A (zh) * 2021-04-20 2021-07-23 潘付强 用于电子烟的雾化部件烧结方法

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