EP0417375A1 - Widerstandsheizelemente mit keramischer Schicht - Google Patents

Widerstandsheizelemente mit keramischer Schicht Download PDF

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Publication number
EP0417375A1
EP0417375A1 EP89810674A EP89810674A EP0417375A1 EP 0417375 A1 EP0417375 A1 EP 0417375A1 EP 89810674 A EP89810674 A EP 89810674A EP 89810674 A EP89810674 A EP 89810674A EP 0417375 A1 EP0417375 A1 EP 0417375A1
Authority
EP
European Patent Office
Prior art keywords
parts
weight
oxide
foil
metal sheet
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.)
Withdrawn
Application number
EP89810674A
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English (en)
French (fr)
Inventor
Fritz K. Kneubühl
Andreas Leupin
Hans Vetsch
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.)
KRELUS AG
Original Assignee
KRELUS AG
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 KRELUS AG filed Critical KRELUS AG
Priority to EP89810674A priority Critical patent/EP0417375A1/de
Publication of EP0417375A1 publication Critical patent/EP0417375A1/de
Withdrawn legal-status Critical Current

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    • 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
    • H05B3/28—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material
    • H05B3/283—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material the insulating material being an inorganic material, e.g. ceramic
    • 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
    • H05B3/18—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor the conductor being embedded in an insulating 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
    • H05B3/20—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
    • H05B3/28—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating 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
    • H05B3/20—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
    • H05B3/28—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material
    • H05B3/30—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material on or between metallic plates

Definitions

  • the present invention relates to a resistance heating element especially for infrared radiators.
  • the heating element comprises a metal layer which is coated with a ceramic coating.
  • the main disadvantage of the foil-type radiators is the damage of the foils caused by corrosive atmospheres.
  • the thickness of this layer has to be as small as possible to prevent a drastic reduction of the heat transfer between the heating foils and the active radiating area by the additional thermal insu­lation.
  • the surface emissivity of the coated foils should be better than or at least comparable to that of the uncoated foils.
  • This second requirement is fulfilled by the admixture of appropriate components into high-temperature ceramic binding agents. Because they resist high temperatures, metal-oxide powders seem to be well suited for this purpose.
  • suitable ceramic coatings for the application on stainless steel foils e.g., the foil sold under the trademark "Krelus Infrared” by Krelus AG, Hirschtal, Switzerland, were found. These ceramic coatings comprise chromium oxide or nickel oxide, cobalt oxide and manganese oxide.
  • An enamel according to the invention made of chromium oxide mixed with ceramic binding agents exhibits a distinct green colour in the visible spectrum. A thin layer of this enamel was sprayed onto a foil with a spray gun and subsequently fired at 1533K. Afterwards, the sample was put to the lifetime test by heating it periodically at least to 1233K. The enamel showed no major visible changes after 2500 cycles.
  • the emissivity of thin layers of various metal-oxide powders namely, of nickel oxide, cobalt oxide, manganese oxide and samarium oxide.
  • nickel and cobalt oxide are grey-black, the manganese oxide brown and the samarium oxide white.
  • cobalt oxide which was measured directly on a flat part of the ori­ginal "Krelus Infrared" foil of the test radiator (I)
  • emissivity measurements on the other powders were per­formed by putting them on a plane silver plate on the test radiator (II).
  • the "Krelus Infrared" foil has the composition, in percent by weight: 0.02 - 0.10 % C 0.10 % Mn max. 19.50 % Cr about 56 % Ni 4.25 % Mo 2.0 % Fe max. 13.5 % Co 1.30 % Al 9.10 % Cu 0.15 % Si max. 0.003 - 0.01 % B 3.00 % Ti.
  • Fig. 2 The result of the emissivity measurements at 1073K are presented in Fig. 2.
  • Curve 1 shows the spectral emissivity of nickel oxide which was stabilized with about 3 mass-% of lithium carbonate. This stabilization is necessary to maintain the grey-black appearance of the oxide during its heating in air [Wells 1975]. Without lithium carbonate the nickel oxide would become green.
  • a suspension of the nickel oxide-lithium carbonate mixture in water was sprayed on the plate with the aid of a spray gun and subsequently fired at approximately the measuring temperature.
  • the resulting layer of the nickel oxide exhibited a uniform emissivity over 0.9 between 1 and 16 ⁇ m wavelength.
  • the spectral emissivity of cobalt oxide at wavelength between 2 and 5 ⁇ m plotted in curve 2 cor­responds to that of the nickel oxide within 1 to 2 %.
  • the samarium oxide exhibits spectral emissivities (curve 4) between 0.8 and 0.9, although it appears white in the visible spectrum.
  • the temperature measurement which underlies the emissivities has an uncertainty of about ⁇ 20K, because we had to perform it with a thermocouple within the supporting silver plate instead of the pyrometer pointed directly to the layer surface.
  • the spectral emissivities of the powders stud­ied are very high, these powders can be applied in technical radiators only by embedment in a binding ceramic matrix.
  • the black enamel for coating the foil consists preferably of an admixture of nickel oxide, cobalt oxide, manganese oxide and, additionally, of iron oxide to other ceramic binding agents (Example 2).
  • the resulting enamel layer on the "Krelus Infrared" foils exhibits a black glossy surface if fired at approximately 1553K and a grey-black dim surface for a firing temperature of about 1473K by using test radiator (I) are present in Fig. 3.
  • the curves 1 a and b illustrate the black glossy layer, the curves 2 a and b the grey-black dim one.
  • the spectral emissivities of an uncoated "Krelus Infrared" foil is plotted again in curve 3.
  • the curves a and b result from two identical measurements on the same sample performed at an interval of approximately one month.
  • the results demonstrate a good reproducibility of the measurements.
  • the spectral emissivities of the enamel show a slight dependence on its firing temperature. At wavelengths below 6 ⁇ m the spectral emissivities of the grey-black dim enamel sample is considerably lower than that of the black glossy one. At wavelengths above 7 ⁇ m the emissivities of the grey-black dim sample are higher. However, the spectral emissivities of the enamel and of the original "Krelus Infrared" foils are of the same order of magnitude.
  • Figs. 6 and 7 the measured temperature dependences of the emissivity of the above-mentioned enamel are presented.
  • the results show only small temperature dependences between 1050 and 1180K with the exception at 1 ⁇ m wavelength, where the uncertainty due to small errors of the temperature measurement is important.
  • a temperature of approximately 1000K both samples exhibit a decrease of the emissivity. Because this temperature is near the lower limit of the measuring range of the two-color pyrometer, which leads to larger errors, this effect may nevertheless be caused by a erroneous temperature measurement. Therefore, it should not be overrated.
  • the spectral emissivities are substantially preserved, especially in the cobalt-containing embodiment.
  • the literature states a spectral emissivity of approximately 0.8 over the spectral range of interest.
  • enamels were applied on original "Krelus Infrared" foils manufactured by the present assignee.
  • the foil is pretreated by artificial ageing, i.e., oxidation in an athmosphere comprising oxygen .
  • the foil is normally pretreated for a period of few minutes (at strongly elevated temperatures) to a period of several days, e.g., 2 days (at normal room temperature).
  • other foils of heating elements show similar results.
  • composition of a chromium-containing enamel The mixture was ground for 70 hours in a jar mill with porcelain balls. The composition of the mixture is indicated in Table 1.
  • Table 1 Component Quantity Chromium(III) oxide 100 g Titanium dioxide 20 g Zinc oxide 20 g Calcium carbonate 50 g Silicon dioxide K50 100 g Feldspar 50 g Phonolite 50 g Potassium carbonate 20 g Water, distilled 250 ml Ethanol 250 ml Abrasion of mill 3.5 g/70 h

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Coating By Spraying Or Casting (AREA)
EP89810674A 1989-09-12 1989-09-12 Widerstandsheizelemente mit keramischer Schicht Withdrawn EP0417375A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP89810674A EP0417375A1 (de) 1989-09-12 1989-09-12 Widerstandsheizelemente mit keramischer Schicht

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP89810674A EP0417375A1 (de) 1989-09-12 1989-09-12 Widerstandsheizelemente mit keramischer Schicht

Publications (1)

Publication Number Publication Date
EP0417375A1 true EP0417375A1 (de) 1991-03-20

Family

ID=8203178

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89810674A Withdrawn EP0417375A1 (de) 1989-09-12 1989-09-12 Widerstandsheizelemente mit keramischer Schicht

Country Status (1)

Country Link
EP (1) EP0417375A1 (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1089594A2 (de) * 1999-09-29 2001-04-04 EVO Elektroheizungen GmbH Heizplatte
WO2003017721A2 (en) * 2001-08-15 2003-02-27 Irina Loktev Electrical heating device
WO2010102392A1 (en) * 2009-03-13 2010-09-16 Shawcor Ltd. Apparatus containing multiple sequentially used infrared heating zones for tubular articles
CN104452261A (zh) * 2014-12-16 2015-03-25 刘桂芹 一种无烟电加热丝剪裁机
CN104525460A (zh) * 2014-12-16 2015-04-22 刘桂芹 一种剪裁机的无烟电加热丝的表面处理方法
CN106191750A (zh) * 2016-06-30 2016-12-07 江苏苏美达机电有限公司 一种取暖器表面涂层及其制造方法
US9669580B2 (en) 2011-11-09 2017-06-06 Saipem S.P.A. Method and apparatus for heating heat-shrinkable pipe sleeves
US10107438B2 (en) 2011-11-10 2018-10-23 Shawcor Ltd. Apparatus containing multiple sequentially used infrared heating zones for tubular articles

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1496482A1 (de) * 1963-01-30 1969-05-14 Eagle Picher Company Porzellanemaille-UEberzugsmasse zum UEberziehen mit Porzellanemaille
FR2091493A5 (de) * 1970-05-12 1972-01-14 Radiation Ltd
FR2140344A1 (en) * 1971-06-02 1973-01-19 Ferro Corp Stain-removing enamel - for self-cleaning cooking stoves
EP0112922A1 (de) * 1982-06-24 1984-07-11 Matsushita Electric Industrial Co., Ltd. Paneelerhitzer
EP0222162A1 (de) * 1985-10-11 1987-05-20 Bayer Ag Flächenheizelemente

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1496482A1 (de) * 1963-01-30 1969-05-14 Eagle Picher Company Porzellanemaille-UEberzugsmasse zum UEberziehen mit Porzellanemaille
FR2091493A5 (de) * 1970-05-12 1972-01-14 Radiation Ltd
FR2140344A1 (en) * 1971-06-02 1973-01-19 Ferro Corp Stain-removing enamel - for self-cleaning cooking stoves
EP0112922A1 (de) * 1982-06-24 1984-07-11 Matsushita Electric Industrial Co., Ltd. Paneelerhitzer
EP0222162A1 (de) * 1985-10-11 1987-05-20 Bayer Ag Flächenheizelemente

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
ADVANCED MATERIALS & PROCESSES. February 1981, METALS PARK, OHIO US pages 84 - 85; & processing databook 81" *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1089594A2 (de) * 1999-09-29 2001-04-04 EVO Elektroheizungen GmbH Heizplatte
EP1089594A3 (de) * 1999-09-29 2001-06-13 EVO Elektroheizungen GmbH Heizplatte
WO2003017721A2 (en) * 2001-08-15 2003-02-27 Irina Loktev Electrical heating device
WO2003017721A3 (en) * 2001-08-15 2004-03-04 Irina Loktev Electrical heating device
EA023779B1 (ru) * 2009-03-13 2016-07-29 Шоукор Лтд. Установка, содержащая последовательно используемые зоны инфракрасного нагрева для трубчатых изделий
CN102387907A (zh) * 2009-03-13 2012-03-21 超科有限公司 包含用于管状物品的多个相继使用的红外加热区的装置
EP2406060B1 (de) 2009-03-13 2016-06-29 ShawCor Ltd. Vorrichtung mit mehreren sequenziell verwendeten ir-heizzonen für rohrförmige artikel
WO2010102392A1 (en) * 2009-03-13 2010-09-16 Shawcor Ltd. Apparatus containing multiple sequentially used infrared heating zones for tubular articles
US9669580B2 (en) 2011-11-09 2017-06-06 Saipem S.P.A. Method and apparatus for heating heat-shrinkable pipe sleeves
US10107438B2 (en) 2011-11-10 2018-10-23 Shawcor Ltd. Apparatus containing multiple sequentially used infrared heating zones for tubular articles
CN104452261A (zh) * 2014-12-16 2015-03-25 刘桂芹 一种无烟电加热丝剪裁机
CN104525460A (zh) * 2014-12-16 2015-04-22 刘桂芹 一种剪裁机的无烟电加热丝的表面处理方法
CN106191750A (zh) * 2016-06-30 2016-12-07 江苏苏美达机电有限公司 一种取暖器表面涂层及其制造方法

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