EP0200126B1 - Méthode de fabrication d'une résistance céramique dépendant de la tension à base de ZnO - Google Patents

Méthode de fabrication d'une résistance céramique dépendant de la tension à base de ZnO Download PDF

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Publication number
EP0200126B1
EP0200126B1 EP86105433A EP86105433A EP0200126B1 EP 0200126 B1 EP0200126 B1 EP 0200126B1 EP 86105433 A EP86105433 A EP 86105433A EP 86105433 A EP86105433 A EP 86105433A EP 0200126 B1 EP0200126 B1 EP 0200126B1
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European Patent Office
Prior art keywords
zno
elements
powder
water
process according
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EP86105433A
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German (de)
English (en)
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EP0200126A1 (fr
Inventor
Maged A. Dr. Osman
Roger Dr. Perkins
Friedrich Dr. Schmückle
Claus Dr. Schüler
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BBC Brown Boveri AG Switzerland
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BBC Brown Boveri AG Switzerland
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/30—Apparatus or processes specially adapted for manufacturing resistors adapted for baking
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
    • H01C7/105—Varistor cores
    • H01C7/108—Metal oxide
    • H01C7/112—ZnO type

Definitions

  • the invention is based on a method for producing a voltage-dependent ceramic resistor based on ZnO.
  • Voltage-dependent resistors (varistors) based on ceramic sintered bodies predominantly containing ZnO are known in numerous variants. Their electrical properties are primarily determined by the additional elements that are mostly present as oxides - including metal oxides in particular. These additives are present in quantities from one thousandth to a few mol percent and must be homogeneously distributed in the ZnO matrix.
  • the currently customary manufacturing processes are usually based on powdered metal oxides.
  • the homogeneity of the materials plays a decisive role, starting with the powder mixture, through the compact to the finished sintered body.
  • the processes provide homogeneous mixing and grinding with the aid of carrier liquids, usually as an aqueous suspension (cf. e.g. EP-A-0 115 149; EP-A-0 115 050; EP-B-0 029 749).
  • the ZnO varistors produced in this way by mixing and grinding powders and then pressing and sintering generally suffer from the lack of sufficient homogeneity of the sintered bodies. It is practically not possible to distribute the additives, sometimes contained in extremely small quantities, evenly in the ZnO crystallites or the grain boundaries. Demixing processes during the manufacturing process, formation of undesired phases due to contamination from abrasion during grinding processes, etc. further deteriorate the physical properties of varistors produced in this way. Exact reproducibility is therefore practically impossible to achieve with these conventional methods.
  • the invention has for its object to provide a method for producing a voltage-dependent ceramic resistor based on ZnO and additional oxides, which leads to the most homogeneous sintered bodies reproducible in the composition and concentration of the various components, and is particularly suitable for targeted and controlled mass production is suitable.
  • the figure shows a flow diagram of the method in block form. The figure requires no further explanation.
  • the essence of the invention is that the additional elements (dopants) are added to a slurry of ZnO powder in the form of water-soluble organic salts.
  • Numerous metal salts of simple organic carboxylic acid such as amic acid, acetic acid, propionic acid, etc. are water soluble.
  • the simple salts of some important elements are insoluble in water. This problem can be avoided by using salts or half salts or mixed salts (NH 4 ) of the di-, tri- and tetra-carboxylic acids.
  • Hydroxycarboxylic acids eg lactic acid, tartaric acid, citric acid
  • are the most suitable for this purpose according to the principle "equal solves equal".
  • NH 3 and organic amines form water-soluble complexes or addition compounds with the organic metal salts, which are also suitable for this purpose.
  • the addition of an ammonium salt of the hydroxycarboxylic acids mentioned often increases the solubility of the simple organic metal salts.
  • Some of the additional elements are also capable of forming acids (e.g. boron, chromium, silicon), whose ammonium salts are water soluble and can be used.
  • Lower alkyl esters such as methyl and ethyl esters of oligo-orthosilicic acid are water soluble and can be used to dope the ceramic with Si.
  • the water is removed from the suspension of ZnO in the aqueous solution, which contains all the additional elements, by spray drying.
  • the suspension is atomized into a jet of fine droplets in a stream of hot air.
  • the water evaporates extremely quickly, and the ZnO particles contained in a droplet bake with the precipitated salts of the additional elements to form compact, spherical agglomerates with a diameter of 5-50 ⁇ m.
  • a free-flowing, easily compressible granulate is created.
  • the salts are deposited on the ZnO particles in an amorphous, ie non-crystalline form. This prevents segregation by crystallization; therefore the distribution of the additional elements is completely homogeneous even in microscopic dimensions.
  • the organic salts can be easily and residue-free converted to metal oxides at relatively low temperatures before or in the first phase of the sintering process. There are no grinding or sieving processes.
  • a voltage-dependent ceramic resistor based on ZnO with the following composition was produced.
  • Tablets of 20 mm in diameter and 5 mm in height were produced from this powder by uniaxial pressing in a steel mold.
  • the tablets were subjected to progressive heat treatment in an air oven.
  • the first phase consisted of heating to a temperature of 650 ° C. in order to convert the additional elements into oxides, which was carried out at a rate of increase of 50 ° C./h.
  • the second phase was a slow increase in temperature from 15 ° C / h to 900 ° C, which was mainly used to completely drive out any decomposition products that might be left behind.
  • the last phase included an increase in temperature from 100 ° C / h up to 1150 ° C and sealing sintering at this temperature for approx. 1 h.
  • the finished sintered body was then cooled to room temperature.
  • a varistor with the following composition was produced according to the procedure given in Example 1:
  • Aqueous solutions of metal salts (corresponding to the required additional elements) of organic acids were first prepared.
  • the elements were selected in the stoichiometric ratio given:
  • the aqueous solution of the metal salts was added to a suspension of 95.5 mol ZnO in 0.5% di-ammonium hydrogen citrate solution with vigorous stirring in a shear mixer. Polyvinyl alcohol was also added to the suspension as a binder. The suspension was then converted into a free-flowing powder in a spray dryer in air. The further procedure corresponded to that in Example 1. The sintering process was carried out at a temperature of 1200 ° C. for 2 hours.
  • a varistor mixture of the following composition was put together using the method given in Example 3 and a varistor sintered body was produced from the powder mixture produced in this way.
  • the additional elements in the form of aqueous and / or colloidal solutions of organic salts or complex compounds of the ZnO slurry in H 2 0 or the latter can be added successively to the former in the preparation of the suspension with stirring.
  • This preferably relates to the elements Bi, Sb, Co, Mn, Ni, Cr, Al, Ga, Ba, B, Si, Ti, Pr, W, rare earths, etc.
  • the following can be used as water-soluble chemical compounds: formates, Acetates, lactates, tartrates, citrates, ammonium citrates, ammonium tartrates etc.
  • the additional element in the form of a water-soluble salt of a hydroxy-substituted or unsubstituted mono-, di-, tri- or tetracarboxylic acid can be added to the ZnO suspension in H 2 O.
  • the additional elements Cr, Si and B can be added to the ZnO suspension in H 2 0 as a real or as a colloidal solution of their acid or as its ammonium salt or as an alkyl ester or as a hydroxide sol, each in H 2 O.
  • Ammkoniak, a hydroxycarboxylic acid ammonium salt or an organic amine can optionally be added to the solutions.
  • ammonium tetraborate ammonium dichromate
  • ammonium silicotate ammonium silicotate
  • oligosilicic acid oligosilicic acid
  • Temperatures of 400 to 650 ° C are generally sufficient to decompose organic residues.
  • the powder or granulate, which is produced by spray drying can also be heated to 400-700 ° C before the uniaxial, two-dimensional radial or isostatic cold pressing. Spray drying itself can also be carried out at temperatures of 400-700 ° C (spray pyrolysis). In both cases, the additional elements are converted into the form of their oxides.
  • the sintering process can be carried out for 1/2 to 2 hours at temperatures between 1100 ° C and 1300 ° C.
  • the voltage-dependent ceramic resistance produced using the new process is characterized by macroscopic and microscopic homogeneous distribution of the additional elements in the ZnO matrix and in the grain boundaries.
  • the phases containing the additional elements show no agglomerations and have a diameter of less than 2 pm.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Manufacturing & Machinery (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Thermistors And Varistors (AREA)

Claims (6)

1. Procédé de fabrication d'une résistance céramique dépendante de la température à base de ZnO et d'autres oxydes choisis dans la classe des éléments d'addition Co, Mn, Cr, Ni, Ba, Bi, Sb, les terres rares, AI, B, Si, Ga, Ti, suivant lequel du ZnO sous forme pulvérulente est d'abord mis en dispersion ou suspension dans une solution aqueuse et/ou est additionné directement de l'élément d'addition en cause sous forme d'un sel ou complexe ou bien colloïde organique en solution ou en suspension dans de l'eau pour les éléments Co, Mn, Ni, AI, Ba, Bi, Sb, Ga, Ti et les terres rares, et sous la forme d'un acide ou de son sel d'ammonium ou ester alcoylique pour les éléments Cr, Si et B, ce mélange, contenant les particules de ZnO en dispersion ou en suspension et tous les autres éléments d'addition en solution aqueuse et/ou colloïdale est séché immédiatement dans un séchoir par pulvérisation à l'air en une poudre ou en granules, cette poudre ou ces granules sont pressés à froid uniaxialement, bidimensionnellement-radialement ou isostatiquement et le corps pressé est ensuite chauffé par stades jusqu'à une température de 650°C, 900°C, puis à une température de 1100 à 1300°C, et le corps fritté fabriqué de cette façon est finalement refroidi jusqu'à la température ambiante.
2. Procédé suivant la revendication 1, caractérisé en ce que les éléments d'addition sont ajoutés chacun sous la forme d'un sel hydrosoluble d'un acide mono-, di-, tri- ou tétracarboxylique hydroxy-substitué ou non substitué à la suspension de ZnO dans de l'eau.
3. Procédé suivant la revendication 1, caractérisé en ce que de l'ammoniac, un sel d'ammonium d'acide hydroxycarboxylique ou une amine organique est ajouté, de surcroît, à la solution aqueuse des sels organiques.
4. Procédé suivant la revendication 1, caractérisé en ce que lors de la préparation de la poudre ou des granules, les éléments d'addition Cr, Si et B sont ajoutés à l'état de solution vraie, à l'état de solution colloïdale de leurs acides, à l'état de leurs sels d'ammonium, à l'état de leurs esters alcoyliques ou à l'état de sol d'hydroxyde, tous dans l'eau, à la suspension de ZnO dans de l'eau.
5. Procédé suivant la revendication 1, caractérisé en ce que la poudre produite par séchage par pulvérisation est chauffée à 40Q-700°C avant le pressage, de façon que tous les éléments d'addition soient convertis en leurs oxydes.
6. Procédé suivant la revendication 1, caractérisé en ce que le mélange qui contient le ZnO et tous les éléments d'addition souhaités est séché par pulvérisation à 400―700°C et les éléments d'addition sont ainsi simultanément convertis en leurs oxydes.
EP86105433A 1985-04-29 1986-04-19 Méthode de fabrication d'une résistance céramique dépendant de la tension à base de ZnO Expired - Lifetime EP0200126B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH180885 1985-04-29
CH1808/85 1985-04-29

Publications (2)

Publication Number Publication Date
EP0200126A1 EP0200126A1 (fr) 1986-11-05
EP0200126B1 true EP0200126B1 (fr) 1990-09-26

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EP86105433A Expired - Lifetime EP0200126B1 (fr) 1985-04-29 1986-04-19 Méthode de fabrication d'une résistance céramique dépendant de la tension à base de ZnO

Country Status (5)

Country Link
US (1) US4767729A (fr)
EP (1) EP0200126B1 (fr)
CN (1) CN1006499B (fr)
DE (1) DE3674451D1 (fr)
IN (1) IN167250B (fr)

Families Citing this family (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3619620A1 (de) * 1986-06-11 1987-12-17 Siemens Ag Verfahren zur herstellung keramischen zinkoxid-varistormaterials und verwendung des nach diesem verfahren hergestellten materials
US5039452A (en) * 1986-10-16 1991-08-13 Raychem Corporation Metal oxide varistors, precursor powder compositions and methods for preparing same
JPH0630284B2 (ja) * 1987-09-11 1994-04-20 富士電機株式会社 電圧非直線抵抗素子の製造方法
JP2620364B2 (ja) * 1988-03-18 1997-06-11 本田技研工業株式会社 セラミックス焼結体の製造方法
US5236632A (en) * 1989-08-10 1993-08-17 Tosoh Corporation Zinc oxide sintered body, and preparation process and use thereof
US4996510A (en) * 1989-12-08 1991-02-26 Raychem Corporation Metal oxide varistors and methods therefor
US5635070A (en) * 1990-07-13 1997-06-03 Isco, Inc. Apparatus and method for supercritical fluid extraction
DE4027927A1 (de) * 1990-09-04 1992-03-05 Bayer Ag Brausekomponente und verfahren zu ihrer herstellung
EP0667626A3 (fr) * 1994-02-10 1996-04-17 Hitachi Ltd Résistance non-linéaire dépendant de la tension et procédé de fabrication.
JP3622774B2 (ja) * 1994-04-18 2005-02-23 株式会社村田製作所 電圧非直線抵抗体の製造方法
US5807510A (en) * 1995-09-07 1998-09-15 Mitsubishi Denki Kabushiki Kaisha Electric resistance element exhibiting voltage nonlinearity characteristic and method of manufacturing the same
AU1887000A (en) * 1999-02-17 2000-09-04 International Business Machines Corporation Microelectronic device for storing information and method thereof
DE10221537A1 (de) * 2002-05-15 2003-11-27 Thueringisches Inst Textil Verfahren zur Herstellung sphärischer, hybridischer Formkörper aus löslichen Polymeren
CN100486928C (zh) * 2006-06-30 2009-05-13 中国科学院合肥物质科学研究院 氧化锌压敏陶瓷及其制备方法
US8512467B2 (en) * 2006-08-21 2013-08-20 Air Products And Chemicals, Inc. Zinc oxide nanoparticle dispersions
WO2008024702A2 (fr) * 2006-08-21 2008-02-28 Air Products And Chemicals, Inc. Dispersions de nanoparticules d'oxyde de zinc
CN101239819B (zh) * 2007-09-14 2012-05-16 深圳顺络电子股份有限公司 片式多层氧化锌压敏电阻陶瓷粉料制备方法
WO2009067178A1 (fr) * 2007-11-20 2009-05-28 Exxonmobil Research And Engineering Company Cermets de borure denses à distribution bimodale ou multimodale avec liant à faible point de fusion
CN101197203B (zh) * 2007-11-30 2010-06-09 华南理工大学 一种氧化锡压敏电阻材料及其制备方法
TWI402864B (zh) * 2008-07-11 2013-07-21 Sfi Electronics Technology Inc 一種氧化鋅變阻器的製法
CN101354936B (zh) * 2008-09-12 2010-09-29 中国西电电气股份有限公司 一种氧化锌电阻片用添加物的制备方法
CN101367649B (zh) * 2008-10-13 2011-08-24 电子科技大学 一种氧化锌压敏电阻介质材料及电阻器制备方法
CN101630553B (zh) 2009-07-17 2011-10-12 立昌先进科技股份有限公司 一种氧化锌变阻器的制备方法
WO2011043207A1 (fr) * 2009-10-07 2011-04-14 堺化学工業株式会社 Particules d'oxyde de zinc, procédé pour la production des particules, charge dissipant la chaleur, composition de résine dissipant la chaleur, graisse dissipant la chaleur et composition de revêtement dissipant la chaleur
CN103011798B (zh) * 2012-12-19 2014-03-05 广西新未来信息产业股份有限公司 一种高焦耳型压敏电阻及其制备方法
CN103011800A (zh) * 2012-12-27 2013-04-03 青岛艾德森能源科技有限公司 一种氧化锌电阻的制备方法
CN103021607A (zh) * 2012-12-27 2013-04-03 青岛艾德森能源科技有限公司 一种氧化锌电阻
DE102016104990A1 (de) * 2016-03-17 2017-09-21 Epcos Ag Keramikmaterial, Varistor und Verfahren zum Herstellen des Keramikmaterials und des Varistors
DE102018116222A1 (de) * 2018-07-04 2020-01-09 Tdk Electronics Ag Keramikmaterial, Varistor und Verfahren zur Herstellung des Keramikmaterials und des Varistors
CN115136260B (zh) * 2019-12-20 2025-03-04 豪倍公司 金属氧化物变阻器配方

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4142996A (en) * 1977-10-25 1979-03-06 General Electric Company Method of making homogenous metal oxide varistor powders
GB1554356A (en) * 1978-04-19 1979-10-17 Power Dev Ltd Resistance materials
DE2910841C2 (de) * 1979-03-20 1982-09-09 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Spannungsabhängiger Widerstandskörper und Verfahren zu dessen Herstellung
US4318995A (en) * 1980-04-25 1982-03-09 Bell Telephone Laboratories, Incorporated Method of preparing lightly doped ceramic materials
CA1206742A (fr) * 1982-12-24 1986-07-02 Hideyuki Kanai Varistor
JPS6021862A (ja) * 1983-07-18 1985-02-04 松下電器産業株式会社 高周波スパツタリング用タ−ゲツト

Also Published As

Publication number Publication date
CN86102994A (zh) 1986-10-29
EP0200126A1 (fr) 1986-11-05
IN167250B (fr) 1990-09-29
US4767729A (en) 1988-08-30
DE3674451D1 (de) 1990-10-31
CN1006499B (zh) 1990-01-17

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