CA2299167A1 - Varistors based on nanocrystalline powders produced by mechanical grinding - Google Patents

Varistors based on nanocrystalline powders produced by mechanical grinding Download PDF

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Publication number
CA2299167A1
CA2299167A1 CA002299167A CA2299167A CA2299167A1 CA 2299167 A1 CA2299167 A1 CA 2299167A1 CA 002299167 A CA002299167 A CA 002299167A CA 2299167 A CA2299167 A CA 2299167A CA 2299167 A1 CA2299167 A1 CA 2299167A1
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CA
Canada
Prior art keywords
varistors
breakdown voltage
nanocrystalline powders
voltage
mechanical grinding
Prior art date
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Granted
Application number
CA002299167A
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French (fr)
Other versions
CA2299167C (en
Inventor
Robert Schulz
Alain Joly
Houshang Alamdari
Andre Van Neste
Sabin Boily
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Hydro Quebec
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Individual
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Publication date
Priority claimed from CA002211813A external-priority patent/CA2211813A1/en
Application filed by Individual filed Critical Individual
Priority to CA002299167A priority Critical patent/CA2299167C/en
Publication of CA2299167A1 publication Critical patent/CA2299167A1/en
Application granted granted Critical
Publication of CA2299167C publication Critical patent/CA2299167C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • 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
    • H01C17/06546—Oxides of zinc or cadmium
    • 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

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

Abstract

L'invention concerne de nouvelles varistances à base d'oxyde de zinc ainsi qu'une méthode de fabrication de celle-ci, dans laquelle on utilise comme produits de départ des poudres nanocristallines obtenues par broyage mécanique intense et on fait subir au mélange obtenu à partir de ces poudres nanocristallines un traitement de consolidation tel qu'un frittage, dans des conditions de température et de temps adéquatement choisies de façon à conserver la plus petite taille possible de grains de ZnO. Les varistances ainsi obtenues ont une microstructure très fine, homogène et une taille moyenne des grains typiquement inférieure ou égale a 3 .mu.m, ce qui est cinq fois plus petit que la taille de grains des matériaux conventionnels. Ces nouvelles varistances ont un plus grand nombre de joints de grain par unité de longueur et donc une tension de claquage beaucoup plus élevée. Cette tension est typiquement supérieure à 10 kV/cm et peut atteindre 17 kV/cm ce qui est presqu'un ordre de grandeur au dessus de la tension de claquage des varistances conventionnelles. Le coefficient de non-linéarité de la courbe de courant-tension est aussi amélioré. Il est supérieur à 20 et peut atteindre des valeurs aussi élevées que 60. En outre, les courants de fuite en dessous de la tension de claquage des varistances ainsi produites, sont plus faibles.The invention relates to new varistors based on zinc oxide and to a method of manufacturing the same, in which nanocrystalline powders obtained by intense mechanical grinding are used as starting materials and the mixture obtained is subjected to from these nanocrystalline powders, a consolidation treatment such as sintering, under conditions of temperature and time suitably chosen so as to keep the smallest possible size of ZnO grains. The varistors thus obtained have a very fine, homogeneous microstructure and an average grain size typically less than or equal to 3 .mu.m, which is five times smaller than the grain size of conventional materials. These new varistors have a greater number of grain boundaries per unit of length and therefore a much higher breakdown voltage. This voltage is typically greater than 10 kV / cm and can reach 17 kV / cm which is almost an order of magnitude above the breakdown voltage of conventional varistors. The coefficient of non-linearity of the current-voltage curve is also improved. It is greater than 20 and can reach values as high as 60. In addition, the leakage currents below the breakdown voltage of the varistors thus produced are lower.

CA002299167A 1997-08-13 1998-08-11 Varistors based on nanocrystalline powders produced by mechanical grinding Expired - Fee Related CA2299167C (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA002299167A CA2299167C (en) 1997-08-13 1998-08-11 Varistors based on nanocrystalline powders produced by mechanical grinding

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CA2,211,813 1997-08-13
CA002211813A CA2211813A1 (en) 1997-08-13 1997-08-13 Nanocrystalline-based varistors produced by intense mechanical milling
PCT/CA1998/000769 WO1999009564A1 (en) 1997-08-13 1998-08-11 Varistors based on nanocrystalline powders produced by mechanical grinding
CA002299167A CA2299167C (en) 1997-08-13 1998-08-11 Varistors based on nanocrystalline powders produced by mechanical grinding

Publications (2)

Publication Number Publication Date
CA2299167A1 true CA2299167A1 (en) 1999-02-25
CA2299167C CA2299167C (en) 2003-07-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
CA002299167A Expired - Fee Related CA2299167C (en) 1997-08-13 1998-08-11 Varistors based on nanocrystalline powders produced by mechanical grinding

Country Status (1)

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CA (1) CA2299167C (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112624740A (en) * 2020-12-26 2021-04-09 重庆材料研究院有限公司 High-entropy NTC thermistor ceramic material and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112624740A (en) * 2020-12-26 2021-04-09 重庆材料研究院有限公司 High-entropy NTC thermistor ceramic material and preparation method thereof
CN112624740B (en) * 2020-12-26 2022-08-02 重庆材料研究院有限公司 High-entropy NTC thermistor ceramic material and preparation method thereof

Also Published As

Publication number Publication date
CA2299167C (en) 2003-07-15

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