WO2001089265A1 - Procede de fabrication d'elements de chauffage a resistance electrique et elements ainsi produits - Google Patents

Procede de fabrication d'elements de chauffage a resistance electrique et elements ainsi produits Download PDF

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Publication number
WO2001089265A1
WO2001089265A1 PCT/GB2000/001885 GB0001885W WO0189265A1 WO 2001089265 A1 WO2001089265 A1 WO 2001089265A1 GB 0001885 W GB0001885 W GB 0001885W WO 0189265 A1 WO0189265 A1 WO 0189265A1
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WO
WIPO (PCT)
Prior art keywords
metal
layer
particles
resistive
electrically
Prior art date
Application number
PCT/GB2000/001885
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English (en)
Inventor
Jeffery Boardman
Original Assignee
Bdsb Holdings Limited
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 Bdsb Holdings Limited filed Critical Bdsb Holdings Limited
Priority to PCT/GB2000/001885 priority Critical patent/WO2001089265A1/fr
Priority to AU2000249343A priority patent/AU2000249343A1/en
Publication of WO2001089265A1 publication Critical patent/WO2001089265A1/fr

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Classifications

    • 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
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
    • H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
    • H05B3/24—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor being self-supporting
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/06—Apparatus or processes specially adapted for manufacturing resistors adapted for coating resistive material on a base
    • H01C17/065—Apparatus or processes specially adapted for manufacturing resistors adapted for coating resistive material on a base by thick film techniques, e.g. serigraphy
    • H01C17/06506—Precursor compositions therefor, e.g. pastes, inks, glass frits
    • H01C17/06513—Precursor compositions therefor, e.g. pastes, inks, glass frits characterised by the resistive component
    • H01C17/06533—Precursor compositions therefor, e.g. pastes, inks, glass frits characterised by the resistive component composed of oxides
    • 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

Definitions

  • the present invention concerns a method of producing electrically resistive heating elements applied directly onto an electrically conductive substrate without the need for an electrically insulating intermediate layer.
  • the invention also encompasses electrical heating elements when produced by the new method.
  • the first method is to screen print a resistive track in a variety of configurations onto a suitably prepared conductive substrate, which in this case is invariably metal.
  • an insulating layer is first applied to the conductive surface which is to receive the resistive track.
  • the insulating layer is generally of a material type compatible in properties with both the conductive metal substrate and the resistive element. It may be applied to the conductive metal substrate in a variety of ways but is generally done so by screen printing using two or more steps, each consisting of a printing, drying and firing operation.
  • the use of multiple steps in the application of the dielectric insulating layer to the conductive supporting substrate is intended to eliminate the chance of defects in any one layer coinciding with defects in either a preceding or succeeding layer, and causing the dielectric layer to lose its insulating properties.
  • the required electrically resistive tracks may be screen printed onto the dielectric layer to form an electrical element of the required configuration.
  • the track configuration is generally applied in several stages. The material comprising the matrix within which the resistive component is suspended needs to match the properties of the preceding insulating layer.
  • the second method comprises the deposition, by flame spraying, of a metal oxide or oxides onto an electrically conductive supporting substrate.
  • Such substrate also incorporates an electrically insulating dielectric layer, applied to the surface to which the electrically resistive oxide is to be applied by flame spraying to form the electrical heating element, generally as described in patents EU302589, US5039840 and patent application No. PCT/GB96/01351.
  • a supporting substrate is required for both types of elements produced by the precedingly described processes as the materials forming the electrically resistive elements do not have sufficiently high intrinsic strengths to be self-supporting.
  • the resistive materials used in the firstly described process are generally based on silver palladium compounds, with resistivities in the region of 10 to 160m ⁇ square for thicknesses of 20 ⁇ m.
  • the resistivities of the metal oxides produced by the second method are higher, ranging from 100 to 3000 ohm mms, the elements so produced do need to have a track length greater than their thickness by a large ratio.
  • the material used to form the insulating dielectric layer must be compatible with both the type of metal used to the supporting substrate and the resistive layer applied to it.
  • This compatibility usually requires the metal and dielectric material to have matching, or nearly matching, coefficients of thermal expansion and good adhesion one to the other.
  • the metal substrate material may be aluminium, copper, mild or stainless steel with alumina, alumina titania, magnesia, or any combination of insulating metal oxides, or even an enamel or glass ceramic used as the dielectric/insulating layer.
  • the adhesion is dependent upon some form of metal surface pre-treatment and chemical bonding mechanism. Failure to achieve the requisite metal to insulation bond will result in element failure where separation occurs.
  • the prime requirement of the intermediate layer is that it provides sufficient electrical insulation between the resistive element track and the metal substrate to meet the appropriate requirements of the various standards used to determine the safe operating conditions and properties of the various types of elements and associated applications.
  • insulating materials may have high dielectric properties, a defect or hole in one part or area beneath the resistive element track will result in either failure in service or non-compliance with the appropriate regulations and standards.
  • the insulating material to the metal substrate in a series of thin layers.
  • the deposition of the dielectric layer is a multi-stage process, generally requiring high energy input at each stage.
  • the production of the insulating layer is comparatively expensive and can constitute the major cost component for the manufacture of the appropriate element system.
  • the thermal conductivity of the insulating layer effectively determines the operating conditions for the whole element system. It is not unknown for a metal substrate to water interface to be at only 104°C whilst the element operating temperature is in excess of 250° C, due entirely to the poor thermal conductivity of the insulating layer.
  • the present invention seeks to overcome or substantially reduce the problems described above associated with the known element systems and manufacturing techniques.
  • a method of producing an electrically resistive heating element having an electrically resistive oxide layer applied directly onto a conductive metal substrate for use in generating heat by the passage of electrical current therethrough comprising:
  • an electrically resistive heating element comprising a substrate of an electrically conducting metal, an electrically resistive oxide layer applied directly to one surface of the conductive metal substrate, and an electrically conductive contact layer disposed over at least part of the electrically resistive oxide layer such that, in use, an electrical current may be passed from the contact layer through the thickness of the electrically resistive oxide layer to the metal substrate via electrical connections made to the contact layer and the metal substrate, respectively, the electrically resistive oxide layer comprising particles of metal powder, pre-oxidised to produce a layer of metal oxide on the surface of each metal particle, deposited onto the surface of said conductive metal substrate.
  • the contact layer may consist of any electrically conductive metals, such as copper, nickel, aluminium, gold, silver, brass, non-metals, conductive polymers or combinations of metals, non-metals or polymer, applied to the resistive oxide layer by means of flame spraying, chemical vapour deposition or magnetron sputtering techniques, electrolytic or chemical processes, or a solid piece held in place with adhesives, mechanical pressure or magnetic means.
  • electrically conductive metals such as copper, nickel, aluminium, gold, silver, brass, non-metals, conductive polymers or combinations of metals, non-metals or polymer
  • the processes used to apply the conductive contact layer to the resistive layer may range from chemical vapour deposition, magnetron sputtering, hot flame spraying, chemical electrolytic or mechanical means or combinations of said means.
  • the contact layer is preferably smaller in area than the resistive oxide layer so as to leave a distance between the outer edge of the contact layer and the outer edge of the oxide layer, sufficient to prevent and electrical current passing directly from the contact area to the metal substrate around the edge of the resistive oxide layer when a voltage is applied between contact and substrate.
  • the metal substrate can consist of any electrically conductive metal or metal alloy.
  • Preferred supporting metal substrates are those which combine good electrical and thermal conductivities and which are readily and economically available, for example copper, aluminium, mold and stainless steels, brasses and bronzes.
  • the conductive metal substrate would have either a flat two dimensional or three dimensional curved form and of a sufficient thickness to provide dimensional stability for the element system during the production process and subsequent operational use.
  • the metal powders to be used are produced by the water or gas atomising process and maybe of any shape ranging from spherical to those having re-entrant angles.
  • the metal powders are of any metal alloy which will react with oxygen to produce an oxide having a resistivity greater than that of the original metal or alloy.
  • the thickness should preferably be such that it will carry the maximum current required for the element and allow it to distribute current evenly over the whole of its surface such that the current passing through the oxide layer from contact layer to metal substrate is uniform in density for each unit area of oxide. This provision ensures that the heat energy generated per unit area is uniform and consequently the element operates at a uniform temperature and does not develop localised hot spots.
  • the resistive oxidised layer may be considered to consist of strings of interconnecting oxidised particles extending through the oxide layer.
  • Each string of oxidised particles may be considered as a "wire” and hence the resistive oxidised layer may be considered as being composed of a multitude of parallel "wires", each wire carrying an appropriate fraction of the overall current.
  • the measured resistance of the element system results from the combined effective resistance of all of the parallel "wires", or particle strings, connecting the contact layer to the metal substrate.
  • the resistivities of the metal oxide or oxide comprising the electrically resistive layer are very substantially greater than the values obtainable by the method set out in patents EU302589, US5039840 and patent application No. PCT/GB96/01351.
  • an element in accordance with the present invention having a resistive oxide layer with a thickness of 100 microns, a heated area of 40cms 2 and resistance of 24 ohms will require the resistivity of the material constituting the resistive layer to be of the order of 100,000 ohm centimetres.
  • the same element resistance and thickness, but with a heated area of 60cms 2 would require the resistivity of the material constituting the resistive layer to be in the region of 150,000 ohm centimetres.
  • the resistive oxide heating layer comprised of the high resistivity oxide materials should preferably be completely free of any defects such as porosity or holes. The presence of any such defects may in some circumstances allow the electrical current to pass directly from the contact layer to the electrically conductive metal substrate with resulting catastrophic failure of the mode previously described for the failure of the dielectric insulating layer with the two existing methods.
  • the method utilised to apply the high resistivity oxidised material to the electrically conductive substrate is preferably such that the oxidised particles have thermal and kinetic energies which are sufficiently high that they deform on impact with the electrically conductive substrate to produce dense homogeneous layers with a high degree of inter-particulate adhesion.
  • resistive materials utilised to produce elements by screen printing do not have resistivities of the magnitude required to meet the requirements of the present invention.
  • resistivities of the magnitude required to meet the requirements of the present invention.
  • such materials as are used need to be enclosed within a glass ceramic matrix to avoid any deleterious reaction with oxygen from their surroundings which will result in failure.
  • the method of oxidising the metal/metal alloy particles comprises any system which exposes the particle surface to the presence of oxygen at a temperature level at which the particular metal will react to form a surface oxide layer.
  • the method utilised to achieve the necessary degree of pre-oxidation of the metal or metal alloy particles may include exposure of the particles to oxygen within a heated furnace or similar heated enclosure, or the passage of the metal particles through an oxidising flame produced by a combination of oxygen and a combustible fuel gas.
  • the heated reacting particles may be projected into a vessel containing water or any other quenching medium which will effectively stop the oxidation reaction which occurs at the outer surface of the heated particles.
  • particles of a conventional alloy having the composition Ni 75%, Cr 15%, Fe 10% will oxidise to the extent of 18-22% by weight when passed through an oxidising flame having the ratio of oxygen to the fuel gas of the order of 5:1 as measured by rates of gas flows at a powder flow rate of approximately 10 grammes per minute and at a distance of 25cm from the surface of the quenching medium.
  • a second oxidation process produces an increase in the region of a further 10-12% by weight, a third oxidation giving an increase in the region of 7-8%.
  • a desired thickness of the resistive oxide layer can be achieved as a result of a plurality of high speed passes of the stream of molten oxide particles over the appropriate area such that any minor defects or porosity in one sub-layer is not coincident with any defect in any preceding or succeeding sub-layer and is generally of the order of 50 to 750 microns.
  • the bulk resistivity for a deposit comprised of oxidised particles having a degree of oxidation by weight of 18-20% of the previously mentioned Ni Cr Fe alloy will be in the region of 30,000 ohm cms, but subsequent oxidation steps increase the resistivity of the material to values of 80,000 ohm cms and 120,000 ohm cms.
  • Alloy metal powders of different compositions will oxidise to greater or lesser extents than the previously mentioned Ni Cr Fe composition resulting in higher or lower bulk resistivity properties.
  • the temperature coefficient of resistance of the electrically resistive layer formed form the high resistivity pre-oxidised particles is dependent by both type and degree on the amount of particle pre-oxidation.
  • the temperature coefficient of resistance is positive for degrees of oxidation up to 10-15% by weight in that the resistance of an electrically resistive layer formed from such particles increases with increase in temperature, the rate of change increasing with the degree of oxidation.
  • the temperature coefficient of resistance becomes increasingly negative in that the resistance of an electrically resistive layer formed from such particles decreases with increasing temperature, the rate of change increasing with the increasing degree of oxidation.
  • the change in the type of temperature coefficient of resistance from positive to negative occurs at greater or lesser degrees of particle pre-oxidation depending on the degree to which alloys of different compositions react in the oxidation process.
  • the resistive oxide layer may be composed for example of two or more sub-layers of oxides of different metals or alloys having different types of temperature resistance coefficients such that the resulting temperature resistance coefficient of the combined layer may be positive, negative or neutral, dependent upon the end use of the said combined resistive oxide layer.
  • the resistive oxide layer may be composed of two or more sublayers which have either positive or negative temperature resistance coefficients, resulting from different degrees of oxidation of particles of the same metal or alloy such that the resulting temperature coefficient of the combined layer may be positive, negative or neutral, dependent upon the end use of the said combined resistive oxide layer.
  • the resistive oxide layer may be composed of a mixture of oxidised particles of a given metal or alloy which have been processed according to a first technique and a second metal oxide combination produced by other means such that the properties of the combined resistive layer change by a substantial degree under pre-determined conditions.
  • the resistive oxide layer can be formed from metal oxide combinations which have the capacity to change their performance characteristics by significant degrees at or about the Curie Point such that the electrically resistive heating element has self controlling or other properties and where the peformance characteristics may be changed under the influence of external stimuli.
  • combinations of oxidised particles within the electrically resistive deposit can be utilised to impart self-regulating characteristics to the said electrically resistive deposit under operating conditions of temperature, applied electrical fields, magnetic influence or stimuli from external radiation.
  • particles of an alloy comprise only of Ni and Cr, such as 80% Ni, 20% Cr, undergo lower degrees of oxidation with successive repetitions of the process previously described and the temperature coefficient of resistance for electrically resistive layers formed from such pre-oxidised particles is invariably positive.
  • the degree of particle pre- oxidation is such that the whole mass of each particle is not normally fully oxidised, but rather that there usually remains a metallic region within the surrounding oxidised layer or at the nucleus of each particle.
  • the "lines” of intimately bonded oxidised particles may be considered to be compared to resistive wires arranged in a parallel configuration and that the power output of the electrically resistive layer comprised of these "lines” is dependent upon that proportion of the total which carries electrical current at any one time.
  • the proportion of the "lines" of oxidised particles comprising the electrically resistive layer which may carry electrical current is dependent upon the area and configuration of the electrically conducive contact layer applied to the resistive oxide layer. Furthermore, for any given value of external electrical supply the power output and heat generating capacity of the electrically resistive layer operating as a heating element is governed by the proportion of the area of the resistive film to which the electrically conducting contact layer is applied and the configuration of that contact layer.
  • resistivity of the oxide layer produced around each oxidised metal particle is far higher than that of the original metal alloy.
  • resistivity of the oxide layers and not the resistivity of the original metal/metal alloy will determine the resistance value measured for such a layer.
  • the conductive paths along which the charge carriers move consist of metal nuclei surrounded by an oxide matrix.
  • NiO, CrO and FeO are of the composition NiO, CrO and FeO. It is known that NiO and CrO are non-conductive at normal temperatures and act as insulators.
  • resistive layers formed from oxidised particles as above would be non-conducting, which is not found to be the case with the resistive layers which are the subject of this present invention.
  • Empirical work has demonstrated that increasing percentages of Fe in the alloy powders promotes the exothermic oxidation reaction and it may be that the FeO produced can not be considered to be non-conductive.
  • the interparticulate contact between successive oxidised particles should be as close as possible, to the extent that the outermost atoms of successive oxide layers may diffuse.
  • pre-oxidised particles of Ni Cr Fe alloy having a negative temperature coefficient of resistance may be deposited in combination with a second oxide having a positive temperature resistance coefficient, such as Barium Titanate, to produce a resistive layer with varying performance characteristics.
  • a second oxide having a positive temperature resistance coefficient such as Barium Titanate
  • the temperature resistance characteristic of Barium Titanate changes by four or five magnitudes at or about the Curie point, and this effect can act as a self-controlling mechanism for electrically resistive heating elements utilising this material.
  • the thermal spraying technique consists of passing a stream of particles through a heat source, during which process the particles become at least partially molten or softened, and when projected onto an appropriate substrate come together to form a homogeneous layer.
  • a heat source for example a flame
  • the pre-oxidised particles pass through the heat source, for example a flame, and are heated sufficiently and acquire sufficient kinetic energy that when they impact onto the substrate, or onto previously deposited oxide particles, they will deform sufficiently that they interlock with the existing surface or particles to produce a cohesive layer consisting of an oxide matrix with metal particles interspersed within it.
  • the method used to heat the pre-oxidised particles to an at least partially molten or softened condition and to deposit the latter particles as a uniform electrically resistive layer onto a supporting substrate may range from processes using combinations of heat and pressure such as hot isostatic pressing to hot spraying techniques.
  • the preferred method for heating the oxidised particles and depositing them as an electrically resistive layer onto the conductive metal substrate is the hot spraying technique as described in patent application WO093/26052.
  • the velocity of the molten or semi-molten oxidised particles on impact with the metal supporting substrate is in excess of 100 metres per second.
  • the heating source may take the form of a plasma device, or an arc struck between two wires or rods, such that the rods or wires melt and molten droplets are projected as a stream onto a surface, or a flame source formed from the reaction of oxygen with hydrocarbon gases or liquids.
  • the most cost effective devices are of the flame spray type utilising combustion gases, such as hydrogen, propane or acetylene, or liquids such as kerosene in combination with oxygen.
  • a preferred method for producing a surface oxide on the metal particles is to pass the particles through an oxidising combustion flame where the ratio of oxygen to the fuel is twice that required for stoichiometric combustion in volumetric terms and then into a receptacle containing a quenching medium whereby the oxidation reaction is stopped.
  • the fuel combining with oxygen in the combustion process to oxidise the metal particles comprises either liquid or gaseous hydrocarbons.
  • the procedure for producing the surface oxide layer on the metal particles is preferably repeated to progressively increase the thickness of the surface oxide layer whilst maintaining the presence of original metal within the oxide layer, the number of repetitions of the oxidising process required to increase the thickness of the surface oxide layer on the metal particles being dependent upon the rate of reaction of the metal or alloy with oxygen and the desired thickness of the surface oxide layer.
  • the surface oxide layer produced on the metal particles when subjected to the oxidising process produces electrically resistive oxide layers with bulk resistivity values in the region of 100 to 200,000 ohm centimetres when deposited onto a suitable prepared metal substrate.
  • the power outputs of the elements produced by the deposition of the electrically resistive layer formed from previously oxidised metal particles onto a conductive metal substrate are capable of variation, not only by virtue of their area and/or thickness, but also and more conveniently by varying the area, shape or configuration of the contact layer applied to that surface not in contact with the conductive metal substrate.
  • a resistive layer is considered hereinafter having the properties previously described, area 40cm 2 , thickness 100 microns and a resistance of 24 ohms for the appropriate bulk resistivity of the pre-oxidised metal particles.
  • the resistive layer is composed of strings of interconnecting oxidised particles which may be considered to be comparable to a multitude of wires in parallel. Accordingly, if a contact layer is applied to the whole area of one side of the resistive layer, then all the strings of interconnecting oxidised particles may be considered to be carrying the current and the heat energy generated and consequently the power output will be maximised.
  • the process described hereinbefore may be used to produce electrically resistive elements utilising not only flat conductive metal substrates, but also curved or cylindrical metal substrates, and in fact any shape or configuration of conductive metal substrate for which a mathematical equation may be derived and used in a computer programme to control a robotic device capable of holding and moving the heat source through which the pre-oxidised metal particles may be caused to pass and subsequently deposited onto the appropriate metal substrate.
  • the surface may need to be pre- treated so that it is substantially chemically clean and roughened to the extent that molten or semi-molten pre-oxidised particles will adhere to it.
  • the process used to prepare the surface of the electrically conductive metal substrate may be any chemical or mechanical technique which after processing preferably produces a chemically clean metal surface with a surface roughness roughly equivalent to that on 60 grit emery paper.
  • Combinations of resistive oxide and conductive contact layers may be applied to suitably prepared supporting metal substrates either in flat, tubular or spherical form, or of any shape for which a mathematical equation may be derived and used in a computer programme to control a robotic device capable of holding the heat source used to deposit the oxidised particles onto the surface of said suitable prepared supporting metal substrate.
  • the electrically resistive elements produced by the aforegoing process are thus not constrained by the need to have an intermediate insulating dielectric layer between the resistive layer and conductive substrate as in the known arrangements, and in consequence will have better thermal conductivity characteristics, may be made with lower thermal mass, operate at higher watts densities, be constructed from combinations of more cost effective materials, and be more tolerant to damage.
  • Fig. 1 is a diagrammatic plan view of an example of a resistive heating element in accordance with the present invention
  • Fig. 2 is a section on I-I in Fig. 1;
  • Figs. 3 and 4 are similar sections of second and third examples of resistive heating elements in accordance with the present invention.
  • Figs. 1 and 2 comprises an electrically resistive oxide layer 10 formed on a conductive metal substrate 12 and carrying an electrically conductive contact layer 14.
  • the resistive layer 10 and contact layer 10, 14 are both rectangular and the conductive metal substrate is a flat/planar plate.
  • the substrate could equally well be tubular or indeed any shape definable by a mathematical equation. Again, the overall shape of the substrate could by any desired configuration, eg. square, rectangular, round.
  • the current flow from the contact layer to the conductive substrate, or vice versa can be considered to be by way of a plurality of generally parallel, linear paths of oxide covered metal particles as indicated diagrammatically by the parallel lines 16.
  • Fig. 3 illustrates an example where the oxide layer is made of layers (two in this case) of different oxides having different characteristics.
  • the oxide layer may be made up of a "sandwich" of different oxides having different coefficients of resistance with temperature.
  • an oxide layer 10a having a negative resistance coefficient with an oxide layer 10b having a positive temperature resistance coefficient can produce a resistive oxide layer having a zero temperature resistance coefficient.
  • a first resistive oxide layer may be combined with a further layer having particular properties.
  • a layer of barium titanate 18 can be applied to the resistive oxide layer 10, where the resistance of the barium, titanate (Ba To 0 3 ) layer increases dramatically, typically by 1000- 10,000 times, at a temperature corresponding to the Curie Point, at which point/temperature the crystalline structure changes from tetragonal to cubic and effectively acts as a "switch" mechanism, limiting the performance of the combined layer 10, 18.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Resistance Heating (AREA)

Abstract

L'invention concerne un procédé de production d'un élément de chauffage à résistance électrique et un élément de chauffage à résistance électrique formé selon le procédé, doté d'une couche d'oxyde résistante appliquée directement sur le substrat métallique conducteur servant à générer de la chaleur par application d'un courant électrique. Le procédé consiste a) à oxyder des particules de poudre métallique afin de produire une couche d'oxyde de métal sur la surface de chaque particule de poudre métallique, b) à chauffer les particules pré-oxydées à une température à laquelle les particules deviennent au moins partiellement fondues ou ramollies, c) à déposer lesdites particules sur une surface d'un substrat métallique conducteur pour former une couche à résistance électrique, et d) à déposer une couche contact conductrice sur la surface de la couche d'oxyde résistante afin de former un élément à résistance électrique ayant des voies de conduction de courant qui traversent l'épaisseur de la couche résistante entre le substrat conducteur et la couche contact conductrice.
PCT/GB2000/001885 2000-05-17 2000-05-17 Procede de fabrication d'elements de chauffage a resistance electrique et elements ainsi produits WO2001089265A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/GB2000/001885 WO2001089265A1 (fr) 2000-05-17 2000-05-17 Procede de fabrication d'elements de chauffage a resistance electrique et elements ainsi produits
AU2000249343A AU2000249343A1 (en) 2000-05-17 2000-05-17 A method of producing electrically resistive heating elements and elements so produced

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Application Number Priority Date Filing Date Title
PCT/GB2000/001885 WO2001089265A1 (fr) 2000-05-17 2000-05-17 Procede de fabrication d'elements de chauffage a resistance electrique et elements ainsi produits

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2419505A (en) * 2004-10-23 2006-04-26 2D Heat Ltd Adjusting the resistance of an electric heating element by DC pulsing a flame sprayed metal/metal oxide matrix
WO2013156162A3 (fr) * 2012-04-20 2013-12-05 Universität Bremen (Bccms) Dispositif de chauffage électrique, composant et leur procédé de fabrication

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3872419A (en) * 1972-06-15 1975-03-18 Alexander J Groves Electrical elements operable as thermisters, varisters, smoke and moisture detectors, and methods for making the same
US5869808A (en) * 1992-11-09 1999-02-09 American Roller Company Ceramic heater roller and methods of making same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3872419A (en) * 1972-06-15 1975-03-18 Alexander J Groves Electrical elements operable as thermisters, varisters, smoke and moisture detectors, and methods for making the same
US5869808A (en) * 1992-11-09 1999-02-09 American Roller Company Ceramic heater roller and methods of making same

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2419505A (en) * 2004-10-23 2006-04-26 2D Heat Ltd Adjusting the resistance of an electric heating element by DC pulsing a flame sprayed metal/metal oxide matrix
WO2013156162A3 (fr) * 2012-04-20 2013-12-05 Universität Bremen (Bccms) Dispositif de chauffage électrique, composant et leur procédé de fabrication
CN104584681A (zh) * 2012-04-20 2015-04-29 不来梅大学(Bccms) 电加热装置、构件及其制造方法
JP2015515104A (ja) * 2012-04-20 2015-05-21 ウニヴェルジテート・ブレーメン（ブレーメン・センター・フォー・コンピュテーショナル・マテリアルズ・サイエンス） 電気式の加熱装置及び構成要素並びに電気式の加熱装置及び構成要素素子を製造するための方法
US20150189699A1 (en) * 2012-04-20 2015-07-02 Universitat Breman (Bccms) Electrical heating device, component and method for the production thereof
US10231287B2 (en) 2012-04-20 2019-03-12 Universitat Bremen (Bccms) Electrical heating device, component and method for the production thereof

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