WO2011129678A1 - Ceramic composition, low voltage zinc oxide varistor made from the ceramic composition and process for manufacturing the low voltage zinc oxide varistor - Google Patents

Ceramic composition, low voltage zinc oxide varistor made from the ceramic composition and process for manufacturing the low voltage zinc oxide varistor Download PDF

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WO2011129678A1
WO2011129678A1 PCT/MY2010/000051 MY2010000051W WO2011129678A1 WO 2011129678 A1 WO2011129678 A1 WO 2011129678A1 MY 2010000051 W MY2010000051 W MY 2010000051W WO 2011129678 A1 WO2011129678 A1 WO 2011129678A1
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mole
ceramic composition
zinc oxide
low voltage
oxide varistor
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Bin Mahmud Shahrom
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Universiti Sains Malaysia
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Priority to PCT/MY2010/000051 priority Critical patent/WO2011129678A1/en
Priority to MYPI2010003812A priority patent/MY165272A/en
Priority to TW100112706A priority patent/TW201210987A/en
Publication of WO2011129678A1 publication Critical patent/WO2011129678A1/en

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    • 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
    • C04B35/453—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 zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
    • 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
    • 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
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Definitions

  • the present invention generally relates to voltage-dependent varistors, and more particularly to a ceramic composition for low voltage zinc oxide varistor, a low voltage zinc oxide varistor made from the ceramic composition, and further to a process for manufacturing the low voltage zinc oxide varistor.
  • ZnO varistors are the electronic components that are most widely used to protect electronic devices and electrical circuits from hazardous electrical transients and surges. They are normally connected in parallel to the devices that are being protected. Under normal steady state operation, a varistor is dormant; it is a state known as the sleep mode. If an electrical transient/surge is present, the varistor detects it in nanosecond speed and switches into a highly conductive state thereby creating a low impedance path to divert the electrical transient/surge away from the electronic devices but into the varistor. Thus, the varistor absorbs the energy of the electrical transient/surge or diverts the electrical transient/surge to ground if the varistor is grounded.
  • ZnO zinc oxide
  • the switch of a varistor occurs at a threshold voltage that is 15%-20% higher than the maximum continuous operating voltage of the device being protected. Above the threshold voltage, the varistor is highly nonlinear and draws in huge currents with little voltage increase. In this nonlinear region, the current-voltage characteristics is commonly expressed as equation (1):
  • the ceramic compositions are optimized to produce low voltage zinc oxide varistors with excellent electrical properties for the full range of the ohmic and nonlinear current- voltage spectra.
  • One embodiment of the present invention provides a ceramic composition comprises zinc oxide and metal oxide additives of Bi, Co, Ni, Ti, Mn, Si, and B, wherein the ceramic composition comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si, 0.01 to 0.1 mole % of B, and 90 to 99 mole % of ZnO; wherein the ceramic composition is used to manufacture a sintered body for making a low voltage zinc oxide varistor.
  • the ceramic composition comprises 0.2 to 3 mole % of Bi 2 0 3 , 0.2 to 2 mole % of Co 2 0 3 , 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti0 2 , 0.2 to 2 mole % of Mn 2 0 3 , 0.01 to 1 mole % of Si0 2 , 0.01 to 1 mole % of B 2 0 3 , and 95 to 99 mole % ZnO.
  • the ceramic composition comprises 0.5 to 1 mole % of Bi 2 0 3 , 0.3 to 0.7 mole % of C02O3, 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti0 2 , 0.3 to 0.7 mole % of Mn 2 0 3 , 0.02 to 0.05 mole % of Si0 2 , 0.05 to 0.08 mole % of B 2 0 3 , and 95 to 99% ZnO.
  • a low voltage zinc oxide varistor comprising a sintered body, a pair of electrode layers sandwiching the sintered body in ohmic contact, a pair of solder contacts conductively coupling with the electrode layers, and a pair of wire leads conductively coupled with the electrode layers via the solder contact; wherein the sintered body is made of a ceramic composition, and wherein the ceramic composition comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si, 0.01 to 0.1 mole % of B, and 90 to 99 mole % of ZnO.
  • the sintered body is any suitable form selected from the group consisting of circular disc, square plate or rectangular plate.
  • the ceramic composition comprises 0.2 to 3 mole % of Bi 2 0 3 , 0.2 to 2 mole % of Co 2 0 3 , 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti0 2 , 0.2 to 2 mole % of Mn 2 0 3 , 0.01 to 1 mole % of Si0 2 , 0.01 to 1 mole % of B 2 0 3 , and 95 to 99 mole % ZnO.
  • the ceramic composition comprises 0.5 to 1 mole % of Bi 2 0 3 , 0.3 to 0.7 mole % of Co 2 0 3 , 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti0 2 , 0.3 to 0.7 mole % of Mn 2 0 3 , 0.02 to 0.05 mole % of Si0 2 , 0.05 to 0.08 mole % of B 2 0 3 , and 95 to 99% ZnO.
  • FIG 1 is a partial cross-section view of a varistor in accordance with one embodiment of the present invention.
  • FIG 2 is a graph showing voltage-current characteristics of exemplary varistors in accordance with embodiments of the present invention. Detailed Description of the Invention
  • FIG 1 shows a partial cross-section view of a low voltage zinc oxide varistor in accordance with one embodiment of the present invention.
  • the varistor comprises a sintered body 1, a pair of electrode layers 2 sandwiching the sintered body in ohmic contact, a pair of solder contacts 3 conductively coupling with the electrode layers, and a pair of wire leads 4 conductively coupled with the electrode layers via the solder contact.
  • the sintered body 1 can be any suitable form; for example, circular disc, square plate or rectangular plate.
  • the sintered body 1 is made from a ceramic composition that is comprised of zinc oxide and various metal oxides.
  • the ceramic composition comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si, 0.01 to 0.1 mole % of B, and 90 to 99 mole % of ZnO.
  • the ceramic composition preferably comprises 0.2 to 3 mole % of Bi 2 0 3 , 0.2 to 2 mole % of Co 2 0 3 , 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti0 2 , 0.2 to 2 mole % of Mn 2 0 3 , 0.01 to 1 mole % of Si0 2 , 0.01 to 1 mole % of B 2 0 3 , and 95 to 99 mole % ZnO.
  • the ceramic composition preferably comprises 0.5 to 1 mole % of Bi 2 0 3 , 0.3 to 0.7 mole % of Co 2 0 3 , 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti0 2 , 0.3 to 0.7 mole % of Mn 2 0 3 , 0.02 to 0.05 mole % of Si0 2 , 0.05 to 0.08 mole % of B 2 0 3 , and 95 to 99% ZnO.
  • the sintered body 1 comprises about 90 to about 99 mole
  • the composition of the metal oxide additives comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si and 0.01 to 0.1 mole % of B.
  • the composition of the metal oxide additives comprises 0.2 to 3 mole % of Bi 2 0 3 , 0.2 to 2 mole % of Co 2 0 3 , 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti >, 0.2 to 2 mole % of Mn 2 0 3 , 0.01 to 1 mole % of Si0 2 , and 0.01 to 1 mole % of B 2 0 3 .
  • the composition of the metal oxide additives preferably comprises 0.5 to 1 mole % of Bi 2 0 3 , 0.3 to 0.7 mole % of Co 2 0 3 , 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti0 2 , 0.3 to 0.7 mole % of Mn 2 0 3 , 0.02 to 0.05 mole % of Si0 2 , and 0.05 to 0.08 mole % of B 2 0 3 .
  • the ceramic composition for making the sintered body of the low voltage zinc oxide varistor is listed in Table I.
  • Three batches of ZnO (A, B, C) with white seal grade were obtained from three different ZnO manufacturers.
  • the specific surface area of the three ZnO powder types varied from about 4.3 to about 5.7 m 2 /g.
  • Three batches of ceramic compositions of which each containing one batch of ZnO (A, B or C) were homogenously mixed with distilled water and organic binder in a ball mill containing zirconia grinding media. A deflocculant was added to obtain correct slurry viscosity.
  • the ratio of solid content to liquid content was about 65:35.
  • the slurry was dried without, segregation, sieved to less than 200 ⁇ size and pressed into discs at about 15 kpsi.
  • the green varistor discs were sintered at a temperature in the range of about 1100°C to about 1300°C for a time in the range of about 1 h to about 3 h in air. Electrode layers and wire leads were applied to the sintered body via conventional methods.
  • One exemplary varistor was 13-mm diameter low voltage varistor model for testing hereinbelow.
  • FIG 2 shows typical voltage-current characteristics of the tested varistors made in accordance with the present invention.
  • the destructive surge test were done up to 1000 A peak current under a 8 ⁇ 20 ⁇ 5 waveshape and the varistors exhibited extraordinary energy handling capability at 1000 A peak current that are not previously known.
  • These high performance varistors are excellent surge suppressing components for lightning-prone regions with high frequencies of lightning-induced electrical surges.

Abstract

The present invention provides a ceramic composition for manufacturing a low voltage zinc oxide varistors. The present invention further provides a low voltage zinc oxide varistor. The present invention also provides a process for manufacturing the low voltage zinc oxide varistor. Superior energy handling capabilities are demonstrated by the low voltage varistors in that the varistors are capable of handling very high surge peak currents over twice the peak current specified by international standards.

Description

CERAMIC COMPOSITION, LOW VOLTAGE ZINC OXIDE VARISTOR MADE FROM THE CERAMIC COMPOSITION AND PROCESS FOR MANUFACTURING THE LOW VOLTAGE ZINC OXIDE VARISTOR Field of the Invention
[0001] The present invention generally relates to voltage-dependent varistors, and more particularly to a ceramic composition for low voltage zinc oxide varistor, a low voltage zinc oxide varistor made from the ceramic composition, and further to a process for manufacturing the low voltage zinc oxide varistor.
Background of the Invention
[0002] Currently, zinc oxide (ZnO) varistors are the electronic components that are most widely used to protect electronic devices and electrical circuits from hazardous electrical transients and surges. They are normally connected in parallel to the devices that are being protected. Under normal steady state operation, a varistor is dormant; it is a state known as the sleep mode. If an electrical transient/surge is present, the varistor detects it in nanosecond speed and switches into a highly conductive state thereby creating a low impedance path to divert the electrical transient/surge away from the electronic devices but into the varistor. Thus, the varistor absorbs the energy of the electrical transient/surge or diverts the electrical transient/surge to ground if the varistor is grounded.
[0003] The switch of a varistor occurs at a threshold voltage that is 15%-20% higher than the maximum continuous operating voltage of the device being protected. Above the threshold voltage, the varistor is highly nonlinear and draws in huge currents with little voltage increase. In this nonlinear region, the current-voltage characteristics is commonly expressed as equation (1):
[0004] I = KV° (1)
[0005] where K is a constant and a is the nonlinear coefficient. With a large value of a, the varistor offers excellent response to transients by conducting current more quickly. The nonlinear coefficient is defined as equation (2):
Figure imgf000003_0001
[0007] where and // are currents at voltages V2 and Vi, respectively, with V2 larger than Vi.
[0008] In countries where lightning occurrence is high, there is an imperative need for electrical surge protection against lightning-induced electrical surges because of their very high energy and peak currents. The lightning-induced surges can cause serious damage to many electrical equipments especially low voltage equipments (below 30 Vrms), and these extreme surges are probable causes of building fires. Summary of the Invention
[0009] It is the objective of the present invention to offer a ceramic composition that can produce varistors with high energy handling capable of handling lightning-induced surges without compromising other varistor characteristics. The ceramic compositions are optimized to produce low voltage zinc oxide varistors with excellent electrical properties for the full range of the ohmic and nonlinear current- voltage spectra.
[0010] One embodiment of the present invention provides a ceramic composition comprises zinc oxide and metal oxide additives of Bi, Co, Ni, Ti, Mn, Si, and B, wherein the ceramic composition comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si, 0.01 to 0.1 mole % of B, and 90 to 99 mole % of ZnO; wherein the ceramic composition is used to manufacture a sintered body for making a low voltage zinc oxide varistor.
[0011] In another embodiment of the ceramic composition, the ceramic composition comprises 0.2 to 3 mole % of Bi203, 0.2 to 2 mole % of Co203, 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti02, 0.2 to 2 mole % of Mn203, 0.01 to 1 mole % of Si02, 0.01 to 1 mole % of B203, and 95 to 99 mole % ZnO.
[0012] In yet another embodiment of the ceramic composition, the ceramic composition comprises 0.5 to 1 mole % of Bi203, 0.3 to 0.7 mole % of C02O3, 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti02, 0.3 to 0.7 mole % of Mn203, 0.02 to 0.05 mole % of Si02, 0.05 to 0.08 mole % of B203, and 95 to 99% ZnO. [0013] Another embodiment of the present invention provides a low voltage zinc oxide varistor comprising a sintered body, a pair of electrode layers sandwiching the sintered body in ohmic contact, a pair of solder contacts conductively coupling with the electrode layers, and a pair of wire leads conductively coupled with the electrode layers via the solder contact; wherein the sintered body is made of a ceramic composition, and wherein the ceramic composition comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si, 0.01 to 0.1 mole % of B, and 90 to 99 mole % of ZnO.
[0014] In another embodiment of the low voltage zinc oxide varistor, the sintered body is any suitable form selected from the group consisting of circular disc, square plate or rectangular plate.
[0015] In another embodiment of the low voltage zinc oxide varistor, the ceramic composition comprises 0.2 to 3 mole % of Bi203, 0.2 to 2 mole % of Co203, 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti02, 0.2 to 2 mole % of Mn203, 0.01 to 1 mole % of Si02, 0.01 to 1 mole % of B203, and 95 to 99 mole % ZnO.
[0016] In another embodiment of the low voltage zinc oxide varistor, the ceramic composition comprises 0.5 to 1 mole % of Bi203, 0.3 to 0.7 mole % of Co203, 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti02, 0.3 to 0.7 mole % of Mn203, 0.02 to 0.05 mole % of Si02, 0.05 to 0.08 mole % of B203, and 95 to 99% ZnO.
[0017] The objectives and advantages of the invention will become apparent from the following detailed description of preferred embodiments thereof in connection with the accompanying drawings.
Brief Description of the Drawings
[0018] Preferred embodiments according to the present invention will now be described with reference to the Figures, in which like reference numerals denote like elements.
[0019] FIG 1 is a partial cross-section view of a varistor in accordance with one embodiment of the present invention.
[0020] FIG 2 is a graph showing voltage-current characteristics of exemplary varistors in accordance with embodiments of the present invention. Detailed Description of the Invention
[0021] The present invention may be understood more readily by reference to the following detailed description of certain embodiments of the invention.
[0022] Throughout this application, where publications are referenced, the disclosures of these publications are hereby incorporated by reference, in their entireties, into this application in order to more fully describe the state of art to which this invention pertains.
[0023] The present invention provides a low- voltage zinc oxide varistor that has improved capability in handling very high energy overvoltage surges without compromising other varistor characteristics. FIG 1 shows a partial cross-section view of a low voltage zinc oxide varistor in accordance with one embodiment of the present invention. As shown in FIG 1, the varistor comprises a sintered body 1, a pair of electrode layers 2 sandwiching the sintered body in ohmic contact, a pair of solder contacts 3 conductively coupling with the electrode layers, and a pair of wire leads 4 conductively coupled with the electrode layers via the solder contact. The sintered body 1 can be any suitable form; for example, circular disc, square plate or rectangular plate.
[0024] The sintered body 1 is made from a ceramic composition that is comprised of zinc oxide and various metal oxides. In one embodiment, the ceramic composition comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si, 0.01 to 0.1 mole % of B, and 90 to 99 mole % of ZnO. In another embodiment, the ceramic composition preferably comprises 0.2 to 3 mole % of Bi203, 0.2 to 2 mole % of Co203, 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti02, 0.2 to 2 mole % of Mn203, 0.01 to 1 mole % of Si02, 0.01 to 1 mole % of B203, and 95 to 99 mole % ZnO. In yet another embodiment, the ceramic composition preferably comprises 0.5 to 1 mole % of Bi203, 0.3 to 0.7 mole % of Co203, 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti02, 0.3 to 0.7 mole % of Mn203, 0.02 to 0.05 mole % of Si02, 0.05 to 0.08 mole % of B203, and 95 to 99% ZnO.
[0025] In one embodiment, the sintered body 1 comprises about 90 to about 99 mole
% of ZnO and about 1 to about 10 mole % of metal oxide additives. The composition of the metal oxide additives comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si and 0.01 to 0.1 mole % of B. In another embodiment, the composition of the metal oxide additives comprises 0.2 to 3 mole % of Bi203, 0.2 to 2 mole % of Co203, 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti >, 0.2 to 2 mole % of Mn203, 0.01 to 1 mole % of Si02, and 0.01 to 1 mole % of B203. In yet another embodiment, the composition of the metal oxide additives preferably comprises 0.5 to 1 mole % of Bi203, 0.3 to 0.7 mole % of Co203, 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti02, 0.3 to 0.7 mole % of Mn203, 0.02 to 0.05 mole % of Si02, and 0.05 to 0.08 mole % of B203.
[0026] In one specific example of the present invention, the ceramic composition for making the sintered body of the low voltage zinc oxide varistor is listed in Table I. Three batches of ZnO (A, B, C) with white seal grade were obtained from three different ZnO manufacturers. The specific surface area of the three ZnO powder types varied from about 4.3 to about 5.7 m2/g. Three batches of ceramic compositions of which each containing one batch of ZnO (A, B or C) were homogenously mixed with distilled water and organic binder in a ball mill containing zirconia grinding media. A deflocculant was added to obtain correct slurry viscosity. The ratio of solid content to liquid content was about 65:35. After ball milling for about 24 h, the slurry was dried without, segregation, sieved to less than 200 μπι size and pressed into discs at about 15 kpsi. The green varistor discs were sintered at a temperature in the range of about 1100°C to about 1300°C for a time in the range of about 1 h to about 3 h in air. Electrode layers and wire leads were applied to the sintered body via conventional methods. One exemplary varistor was 13-mm diameter low voltage varistor model for testing hereinbelow.
[0027]
TABLE I
MATERIAL MOL %
ZnO 97.00
Bi203 0.800
Co203 0.500
NiO 0.500
Ti02 0.600
Mn203 0.500
Si02 0.030
B s 0.070 [0028] The varistors were tested in accordance with European Standard specifications CECC 42201 that are summarized in Table II whereby the specifications are for 13-mm diameter models. FIG 2 shows typical voltage-current characteristics of the tested varistors made in accordance with the present invention. The destructive surge test were done up to 1000 A peak current under a 8χ20μ5 waveshape and the varistors exhibited extraordinary energy handling capability at 1000 A peak current that are not previously known. These high performance varistors are excellent surge suppressing components for lightning-prone regions with high frequencies of lightning-induced electrical surges.
[0029]
TABLE II
Figure imgf000007_0001
[0030] The physical properties of the varistors for the three batches A, B and C are listed in Table III whereby the values are suitable for mass production. The electrical characteristics of the varistors for the three batches A, B and C are listed in Table IV whereby all of the values satisfy the international standard specifications listed in Table I. The varistors' exceptional characteristic of electrical energy handling are shown in Table V whereby the varistors were subjected to current surges with peak currents 1000 A and 2000 A under a 8χ20μ8 waveshape. All varistor samples survived the very destructive tests without any obvious physical damage. Currently specifications for 1000 A and 2000 A current surge tests do not exist for 13-mm diameter low voltage varistor models. The fact that the varistors survived surge current four times that of the international standard is an amazing one indeed. TABLE III
Figure imgf000008_0001
[0031]
TABLE IV
Figure imgf000008_0002
[0032] TABLE V
Figure imgf000009_0001
[0033] While the present invention has been described with reference to particular embodiments, it will be understood that the embodiments are illustrative and that the invention scope is not so limited. Alternative embodiments of the present invention will become apparent to those having ordinary skill in the art to which the present invention pertains. Such alternate embodiments are considered to be encompassed within the scope of the present invention. Accordingly, the scope of the present invention is defined by the appended claims and is supported by the foregoing description.

Claims

What is claimed is: 1. A ceramic composition comprises zinc oxide and metal oxide additives of Bi, Co, Ni, Ti, Mn, Si, and B, wherein the ceramic composition comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si, 0.01 to 0.1 mole % of B, and 90 to 99 mole % of ZnO; wherein the ceramic composition is used to manufacture a sintered body for making a low voltage zinc oxide varistor.
2. The ceramic composition of claim 1, wherein the ceramic composition comprises 0.2 to 3 mole % of Bi203, 0.2 to 2 mole % of Co203, 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti02, 0.2 to 2 mole % of Mn203, 0.01 to 1 mole % of Si02, 0.01 to 1 mole % of B203, and 95 to 99 mole % ZnO.
3. The ceramic composition of claim 1, wherein the ceramic composition comprises 0.5 to 1 mole % of Bi203, 0.3 to 0.7 mole % of Co203, 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti02, 0.3 to 0.7 mole % of Mn203, 0.02 to 0.05 mole % of Si02, 0.05 to 0.08 mole % of B203, and 95 to 99% ZnO.
4. A low voltage zinc oxide varistor comprising a sintered body, a pair of electrode layers sandwiching the sintered body in ohmic contact, a pair of solder contacts conductively coupling with the electrode layers, and a pair of wire leads conductively coupled with the electrode layers via the solder contact; wherein the sintered body is made of a ceramic composition, and wherein the ceramic composition comprises 0.05 to 7 mole % of Bi, 0.05 to 5 mole % of Co, 0.05 to 6 mole % of Ni, 0.05 to 5 mole % of Ti, 0.05 to 5 mole % of Mn, 0.01 to 0.1 mole % of Si, 0.01 to 0.1 mole % of B, and 90 to 99 mole % of ZnO.
5. The low voltage zinc oxide varistor of claim 4, wherein the sintered body is any suitable form selected from the group consisting of circular disc, square plate or rectangular plate.
6. The low voltage zinc oxide varistor of claim 4, wherein the ceramic composition comprises 0.2 to 3 mole % of Bi203, 0.2 to 2 mole % of Co203, 0.2 to 2 mole % of NiO, 0.2 to 2 mole % of Ti02, 0.2 to 2 mole % of Mn203, 0.01 to 1 mole % of Si02, 0.01 to 1 mole % of B203, and 95 to 99 mole % ZnO.
7. The low voltage zinc oxide varistor of claim 4, wherein the ceramic composition comprises 0.5 to 1 mole % of Bi203, 0.3 to 0.7 mole % of Co203, 0.3 to 0.7 mole % of NiO, 0.3 to 1 mole % of Ti02, 0.3 to 0.7 mole % of Mn203, 0.02 to 0.05 mole % of Si02, 0.05 to 0.08 mole % of B203, and 95 to 99% ZnO.
PCT/MY2010/000051 2010-04-12 2010-04-12 Ceramic composition, low voltage zinc oxide varistor made from the ceramic composition and process for manufacturing the low voltage zinc oxide varistor WO2011129678A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2857374A1 (en) * 2013-10-02 2015-04-08 Razvojni Center eNem Novi Materiali d.o.o. Method for manufacturing varistor ceramics and varistors having low leakage current

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1244745A (en) * 1968-10-01 1971-09-02 Matsushita Electric Ind Co Ltd Non-linear resistance material
US3962144A (en) * 1973-10-19 1976-06-08 Matsushita Electric Industrial Co., Ltd. Process for making a voltage dependent resistor
GB2242065A (en) * 1990-03-16 1991-09-18 Ecco Ltd Varistor composition
US5973589A (en) * 1997-06-23 1999-10-26 National Science Council Zno varistor of low-temperature sintering ability
US6146552A (en) * 1995-03-06 2000-11-14 Matsushita Electric Industrial Co., Ltd. Zinc oxide ceramics and method for producing the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1244745A (en) * 1968-10-01 1971-09-02 Matsushita Electric Ind Co Ltd Non-linear resistance material
US3962144A (en) * 1973-10-19 1976-06-08 Matsushita Electric Industrial Co., Ltd. Process for making a voltage dependent resistor
GB2242065A (en) * 1990-03-16 1991-09-18 Ecco Ltd Varistor composition
US6146552A (en) * 1995-03-06 2000-11-14 Matsushita Electric Industrial Co., Ltd. Zinc oxide ceramics and method for producing the same
US5973589A (en) * 1997-06-23 1999-10-26 National Science Council Zno varistor of low-temperature sintering ability

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2857374A1 (en) * 2013-10-02 2015-04-08 Razvojni Center eNem Novi Materiali d.o.o. Method for manufacturing varistor ceramics and varistors having low leakage current

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