JP7242274B2 - voltage nonlinear resistor - Google Patents

Description

The present invention relates to voltage nonlinear resistors.

In power facilities such as substations, overvoltage protection devices such as lightning arresters and surge absorbers are installed to protect switches, transformers, and the like from abnormal voltages such as lightning strikes. These overvoltage protection devices use a voltage nonlinear resistor that has a low resistance when an abnormal voltage is applied. Zinc oxide elements (ZnO elements) containing zinc oxide (ZnO) as a main component and containing at least one kind of additive are mainly used as voltage nonlinear resistors.

On the other hand, in recent years, miniaturization of overvoltage protection devices has been demanded for the purpose of downsizing power equipment and reducing costs. Along with this, the zinc oxide element used in the overvoltage protection device also needs to be miniaturized.

In order to reduce the size of the zinc oxide element, it is necessary to increase the operation start voltage of the voltage non-linear resistor, the so-called varistor voltage. Further, miniaturization of zinc oxide elements leads to an increase in the amount of electric energy applied per unit volume. For this reason, it is necessary to improve the electric energy resistance characteristic of the zinc oxide element and to improve the limiting voltage ratio.

JP-A-2017-130544 (Patent Document 1) is a background art of this technical field. This publication describes a sintered body containing zinc oxide as a main component and bismuth, antimony and boron as secondary components, wherein the secondary component is 1.5 to 2.5 mol of bismuth oxide in terms of oxide. %, 1 to 2 mol % of antimony oxide, and 0.3 mol % or less of boron oxide, a voltage non-linear resistor balanced in varistor voltage, limiting voltage ratio and temperature characteristics. (see summary).

JP 2017-130544 A

Patent Document 1 describes a voltage nonlinear resistor in which varistor voltage, limiting voltage ratio, and temperature characteristics are balanced, as in the present invention. However, the voltage non-linear resistor described in Patent Document 1 mainly corresponds to a varistor voltage of about 600 V/mm per unit thickness of the element.

The present invention provides a voltage non-linear resistor with a well-balanced varistor voltage, limiting voltage ratio, and temperature characteristics, which mainly corresponds to a voltage of about 400 V/mm in terms of varistor voltage per unit thickness of the element.

In order to solve the above-mentioned problems, the present invention includes a sintered body containing zinc oxide as a main component and containing bismuth, antimony and magnesium as auxiliary components. It is characterized by containing 0.50 to 1.45 mol % of bismuth oxide, 1 to 2 mol % of antimony oxide, and 0.02 to 0.06 mol % of magnesium oxide.

According to the present invention, a varistor voltage per unit thickness of the element corresponds mainly to a voltage of about 400 V/mm, and a voltage non-linear resistor is provided in which the varistor voltage, the limiting voltage ratio and the temperature characteristics are well balanced. be able to.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is a schematic diagram explaining the structure of the voltage nonlinear resistor which concerns on a present Example. FIG. 3 is a schematic diagram for explaining the configuration of the cylindrical shape of the sintered body according to the present example. FIG. 3 is a schematic diagram for explaining the configuration of the hollow columnar shape of the sintered body according to the present example. 4 is a graph showing the results of a life test (hollow columnar element: an element with an outer diameter of 130 mm and an inner diameter of 50 mm). It is a graph which shows the result of a lifetime test (cylindrical element with a diameter of 100 mm).

Embodiments of the present invention will be described below with reference to the drawings. In addition, the same reference numerals are given to the same configurations, and the description may be omitted when the description is duplicated.

(1) Configuration of Voltage Nonlinear Resistor FIG. 1 is a schematic diagram illustrating the configuration of the voltage nonlinear resistor according to the present embodiment, and is a front view of the voltage nonlinear resistor.

A voltage nonlinear resistor (zinc oxide element) (hereinafter referred to as a "ZnO element") 100 described in this embodiment includes a sintered body 110, electrodes 120 formed on the upper and lower surfaces of the sintered body 110, and a sintered body. and an insulating layer 130 formed on a side surface of the body 110 .

The sintered body 110 may be cylindrical or hollow cylindrical with a space in the center. When the sintered body 110 has such a shape (cylindrical shape or hollow columnar shape), the insulating layer 130 is formed on the outer peripheral side surface and the inner peripheral side surface of the sintered body 110 .

Such a ZnO element 100 is used for overvoltage protection devices such as lightning arresters and surge absorbers.

FIG. 2A is a schematic diagram illustrating the configuration of the cylindrical shape of the sintered body according to the present example. FIG. 2B is a schematic diagram for explaining the configuration of the hollow columnar shape of the sintered body according to the present example.

The sintered body 110 described in this embodiment may be a cylindrical sintered body 210 as shown in FIG. It may be a sintered body 220 .

In order to realize a ZnO element 100 having a varistor voltage per unit thickness of the element mainly corresponding to a voltage of about 400 V/mm, the present inventors investigated the characteristics of the ZnO element 100 such as varistor voltage, limiting voltage ratio and The composition of the sintered body 110 was examined in order to balance the three items of temperature characteristics at a high level.

As a result, it was found that the ZnO element 100 excellent in the above three items (varistor voltage, limiting voltage ratio, and temperature characteristics) can be realized by setting the sintered body 110 to a predetermined composition.

(2) Structures of Electrodes and Insulating Layers First, the structures (electrodes and insulating layers) of the ZnO element 100 other than the sintered body 110 (210 or 220) will be described.

As a material of the electrode 120, a metal material having electrical conductivity such as aluminum (Al) or copper (Cu), or an alloy material thereof can be used. Organic materials having electrical conductivity can also be used. A composite material of the metal material or alloy material described above and the organic material described above can also be used.

Methods for forming the electrode 120 include arc spraying, plasma spraying, flame spraying, high-speed flame spraying, cold spraying, aerosol deposition, plating, dip coating, and spin coating. A suitable forming method is used depending on the shape and size of the sintered body 110 and the material of the electrode 120 .

Note that the thickness of the electrode 120 is preferably 30 to 200 μm from the viewpoint of adhesion to the sintered body 110 and conductivity.

The insulating layer 130 is formed on the side surface of the sintered body 110 to prevent an electrical short circuit when an electric current is passed through the sintered body 110 via the electrode 120 .

As the material (insulating material) of the insulating layer 130, an inorganic material such as ceramics including electrically insulating glass, an electrically insulating organic material, or a composite material thereof can be used.

The insulating layer 130 is formed by spraying (applying) the above-described material onto the side surface of the sintered body 110 and, if necessary, performing a heat treatment depending on the material used.

As a method for forming the insulating material of the insulating layer 130, depending on the shape and dimensions of the fired body 110, a spray coating method for spraying (applying) the insulating material, a dip coating method for immersing in a solution containing the insulating material, or the like can be used. can be selected as appropriate.

It should be noted that the thickness of the insulating layer 130 is preferably 50 to 300 μm from the viewpoints of adhesion and insulation with the sintered body 110 and from the viewpoint of mechanical strength. The insulating layer 130 may be a single layer of any of the materials described above, or may be a multi-layer of a plurality of types of the materials described above.

(3) Structure of sintered body (3.1) Structure of sintered body The sintered body 110 constituting the ZnO element 100 has a ZnO particle phase composed of ZnO particles as a main component and a subcomponent It is composed of a spinel particle phase, a Bi ₂ O ₃ phase, and the like.

The ZnO particles are the main component of the sintered body 110, and preferably have an average particle size of 15 μm or less. This is because when the average grain size is larger than 15 μm, the varistor voltage per unit thickness becomes smaller than 300 V/mm.

Spinel particles are particles mainly composed of Zn ₇ Sb ₂ O ₁₂ , and are mainly formed from ZnO and Sb ₂ O ₃ during the firing process. The spinel particles have a role of controlling the grain growth of the ZnO particles and have a role of absorbing impurities and some additives in the raw material powder. The spinel particles preferably have an average particle size of 10 μm or less. This is because the limiting voltage ratio becomes 1.55 or more when the average particle diameter is larger than 10 μm.

The Bi ₂ O ₃ phase is mainly present at the grain boundaries of ZnO grains and is a component that develops voltage nonlinearity. In addition, in the sintering process, Bi ₂ O ₃ has a role of promoting grain growth of ZnO grains and a role of controlling properties of ZnO grains at grain boundaries.

(3.2) Types and Contents of Subcomponents As described above, the sintered body 110 is a ZnO-based ceramic material containing zinc oxide (ZnO) as a main component. The content of subcomponents (additives) contained in this ZnO-based ceramic material is 0.50 to 1.45 mol % of bismuth oxide (Bi ₂ O ₃ ) and antimony oxide (Sb ₂ O ₃ ) in terms of oxides. is 1.0 to 2.0 mol%, and magnesium oxide (MgO) is 0.01 to 0.10 mol%.

That is, the sintered body 110 described in this embodiment is a sintered body containing ZnO as a main component and containing bismuth (Bi), antimony (Sb) and magnesium (Mg) as subcomponents. As components, 0.50 to 1.45 mol % of bismuth oxide, 1 to 2 mol % of antimony oxide, and 0.01 to 0.10 mol % of magnesium oxide are contained in terms of oxides.

Bismuth (Bi) is a component that forms a Bi ₂ O ₃ phase mainly at the grain boundary of ZnO and develops voltage nonlinearity. The content is preferably 0.50 to 1.45 mol %, more preferably 0.95 to 1.30 mol % in terms of Bi ₂ O ₃ . If the content is less than 0.50 mol %, the effect of sufficiently improving the limiting voltage ratio cannot be obtained, and if the content is more than 1.45 mol %, the limiting voltage ratio deteriorates.

Antimony (Sb) is an effective component for mainly forming spinel particles together with ZnO and improving the varistor voltage and the limiting voltage ratio. The content is preferably 1.0 to 2.0 mol %, more preferably 1.4 to 1.8 mol % in terms of Sb ₂ O ₃ . If the content is less than 1 mol %, the effect of sufficiently improving the limiting voltage ratio cannot be obtained, and if the content is more than 2 mol %, the temperature characteristics deteriorate.

Magnesium (Mg) is an effective component for improving the limiting voltage ratio and temperature characteristics. The content is preferably 0.01 to 0.10 mol %, more preferably 0.02 to 0.06 mol % in terms of MgO. If the content is less than 0.01 mol %, the effect of sufficiently improving the limiting voltage ratio cannot be obtained, and if the content is more than 0.1 mol %, the limiting voltage ratio deteriorates.

In addition to these, as additives, manganese (Mn), cobalt (Co), chromium (Cr), nickel (Ni), aluminum (Al), silver (Ag), silicon (Si), boron (B) , and/or a rare earth element (RE) can be added as appropriate.

Here, from the viewpoint of improving the limiting voltage ratio and temperature characteristics, the contents of Mn, Co, and Cr are 0.1 to 0.1 in terms of MnCO ₃ , Co ₂ O ₃ , and Cr ₂ O ₃ , respectively. 1.5 mol % is preferred.

Also, from the viewpoint of improving the limiting voltage ratio and temperature characteristics, the content of Ni and B is preferably 0.1 to 2.0 mol % in terms of NiO and 0.3 mol % or less in terms of B ₂ O ₃ . .

Also, from the viewpoint of improving the limiting voltage ratio, the content of Al is preferably 0.005 to 0.500 mol % in terms of Al ₂ O ₃ .

From the viewpoint of improving the limiting voltage ratio, the content of Ag is preferably 0.001 to 0.010 mol % in terms of Ag ₂ O.

Moreover, Si is an effective component for forming Zn ₂ SiO ₄ together with ZnO and improving the varistor voltage and the limiting voltage ratio. Its content is preferably 1.0 to 2.5 mol % in terms of SiO ₂ .

Moreover, from the viewpoint of improving the limiting voltage ratio and the temperature characteristics, the content of the rare earth element (RE) is preferably 2.5 mol % or less in terms of RE ₂ O ₃ . Here, RE is preferably at least one selected from yttrium (Y) and/or lanthanoid rare earth elements. In this embodiment, Y is used as RE.

(4) Method for Producing ZnO Element Next, a method for producing the ZnO element 100 will be described.

First, a predetermined amount of ZnO powder, which is the main component, and the above-described additive are weighed, and then a solvent such as water and a dispersant are added, and a mixture is prepared using a wet pulverization and mixing device. Here, as the wet pulverizing and mixing device, a ball mill using ceramic balls or beads such as zirconia as a pulverizing medium, a circulating pulverizing device, or the like can be used.

The average particle size of the mixture is preferably 3 μm or less, more preferably 1 μm or less. This is because by setting the average particle diameter of the mixture to 3 μm or less, the grain growth of the ZnO particles proceeds uniformly during the firing treatment described below, thereby improving the uniformity of the current path inside the ZnO element.

An organic binder such as polyvinyl alcohol (PVA) is added to this mixture to prepare a slurry for granulation. Using a granulator, this slurry for granulation is heated and dried to produce granulated powder for molding. Here, as the granulator, a rotary disc type or nozzle spray type spray dryer can be used. The granulator can be appropriately selected according to the particle size of the granulated powder to be produced.

The particle size of the granulated powder is preferably 10 μm to 300 μm, more preferably 50 μm to 200 μm. This is because if the particle size of the granulated powder is less than 10 μm, the flowability of the granulated powder is lowered during the molding described below, and a dense compact cannot be obtained. Further, when the particle size of the granulated powder is larger than 300 μm, when the granulated powder is filled into the mold described below, the gaps between the granulated powder become large, and a dense molded body is formed. This is because it cannot be obtained.

The produced granulated powder is filled in a mold and pressure-molded into a predetermined shape using a molding machine such as a hydraulic press to produce a compact. The shape and dimensions of the molded body are appropriately selected according to the application. In addition, in this embodiment, a cylindrical sintered body 210 (110) as shown in FIG. 2A is used for explanation.

A degreasing treatment is performed to remove the organic binder, solvent and dispersant in the molded body by heating the molded body at atmospheric pressure at a predetermined temperature between 350 and 600° C. for 1 to 2 hours. conduct. Here, the temperature and time of the degreasing treatment can be appropriately set according to the type and amount of the organic binder, solvent and dispersant to be added.

After that, the sintered body 110 is produced by heating at a predetermined temperature between 950 and 1200° C. for 1 to 5 hours for firing treatment.

After forming an insulating material for forming the insulating layer 130 around the side surface of the fired body 110 thus produced, heat treatment is performed to form the insulating layer 130 .

After polishing the upper and lower surfaces (circular surfaces) of the sintered body 110 on which the insulating layer 130 is formed, the electrodes 120 are formed on the polished upper and lower surfaces (circular surfaces) of the sintered body 110 to produce the ZnO element 100. do.

Examples of methods for forming the electrode 120 include arc spraying, plasma spraying, flame spraying, high-speed flame spraying, cold spraying, aerosol deposition, plating, dip coating, and spin coating. be. A suitable forming method is used depending on the shape and size of the sintered body 110 and the material of the electrode 120 .

The ZnO element 100 described in this embodiment can suppress the temperature rise associated with the absorption of electric energy and the decrease in resistance value, thereby suppressing the occurrence of thermal runaway of the ZnO element 100 . Therefore, it is possible to reduce the resistance change of the ZnO element 100 due to the temperature change (improve the temperature characteristic), and the ZnO element 100 can be miniaturized.

(5) Evaluation method of ZnO element Next, the evaluation method of the manufactured ZnO element 100 will be described.

(5.1) Varistor voltage and limiting voltage ratio (VI characteristics)
A voltage (V _1mA ) when a current of 1 mA was applied to the ZnO element 100 was measured and used as an operation start voltage (varistor voltage). Here, as the varistor voltage per unit thickness of the ZnO element 100 increases, the number of voltage nonlinear resistors used in the overvoltage protection device can be reduced, and the overvoltage protection device can be miniaturized.

Measure the peak voltage ( _V10kA ) when an impulse current of 10kA is applied, calculate the ratio ( _V10kA / _V1mA ) between the peak voltage ( _V10kA ) and the varistor voltage ( _V1mA ), and determine the limiting voltage ratio. and The smaller the limiting voltage ratio, the better the voltage nonlinearity.

(5.2) Temperature characteristics The varistor voltage ( _V1mA ) was measured at 30°C and 115°C, and the ratio of the varistor voltages at these temperatures ( _V1mA , _115°C /V1mA _{, 30°C} ) was calculated. Characterized. The smaller the temperature characteristic, the better the thermal stability.

In this embodiment, the limiting voltage ratio is 1.55 and the temperature characteristic is 0.90 as evaluation criteria, and the limiting voltage ratio is less than 1.55 and the temperature characteristic is 0.90 or more. (Compatibility) was set as an acceptance criterion. This is because it is possible to suppress the occurrence of thermal runaway of the ZnO element 100 by suppressing the temperature rise accompanying the absorption of electrical energy and suppressing the decrease in the resistance value.

In addition, the ZnO element 100 described in this embodiment can have a varistor voltage of 300 V/mm to 450 V/mm, more preferably 300 V/mm to 400 V/mm.

Regarding the limiting voltage ratio, the JEC (Japanese Electrotechnical Committee) standard standardizes 1.92 to 1.62 according to the element size. This indicates excellent nonlinearity.

(6) Specific ZnO Element A specific ZnO element will be described below.

ZnO elements (Nos. 1 to 44) were produced and evaluated for varistor voltage, limiting voltage ratio and temperature characteristics.

ZnO powder and additives were weighed in predetermined amounts, and then pulverized and mixed in a wet pulverizing and mixing device using zirconia beads. Polyvinyl alcohol was added to this mixture to prepare a slurry for granulation. A granulated powder was produced from this slurry for granulation by using a rotary disc type spray dryer. This granulated powder was put into a mold and pressure-molded by a hydraulic press to produce a compact. The compact was degreased by heating at 500° C. under atmospheric pressure (in the atmosphere), and then fired at 1150° C. to produce a sintered body.

A glass frit was formed on the side surface of the produced fired body and heat-treated to form an insulating layer. Thereafter, the upper and lower surfaces were polished, and aluminum (Al) was arc-sprayed onto the polished upper and lower surfaces using an arc spraying method to form electrodes. The sintered body after polishing has a diameter of 50 mm and a thickness of about 15 mm.

Table 1 shows the composition of the sintered bodies of the ZnO elements (Nos. 1 to 44), and Table 2 shows the evaluation results of the limiting voltage ratio and temperature characteristics. The unit of composition of each component described in Table 1 is "mol%".

In Table 1, all ZnO elements (Nos. 1 to 44) achieve varistor voltages of 300 V/mm to 400 V/mm.

As shown in Table 1, the ZnO elements (Nos. 2 to 5, 8 to 10, 13 to 17, 19 to 22 and 38) having the preferred composition of the sintered body in this example (within the composition range) , a limiting voltage ratio of less than 1.55, and a temperature characteristic of 0.90 or more.

On the other hand, the ZnO elements (Nos. 1, 6, 7, 11, 12, 18, 23 to 37 and 39 to 44), which do not have the preferred composition of the sintered body in this example (outside the composition range), At least one of the limiting voltage ratio of less than 1.55 and the temperature characteristic of 0.90 or more is not achieved, and it can be seen that the limiting voltage ratio and the temperature characteristic of the ZnO element cannot be balanced.

No. 1 to No. 6, when Bi ₂ O ₃ is less than 0.50 mol% (No. 1) or more than 1.45 mol% (No. 6), the limiting voltage ratio is a value greater than 1.55 , and the temperature characteristic also shows a value smaller than 0.90.

No. 7 to No. 11, when Sb ₂ O ₃ is less than 1.0 mol % (No. 7) or more than 2.0 mol % (No. 11), the limiting voltage ratio is greater than 1.55. is shown. In addition, No. As for 7, the temperature characteristic also shows a value smaller than 0.90.

No. 12 to No. 18, when the amount of MgO is less than 0.01 mol % (No. 12) or more than 0.10 mol % (No. 18), the limiting voltage ratio shows a value greater than 1.55. there is

No. 19 to No. 23, when the amount of B ₂ O ₃ is more than 0.3 mol % (No. 16), the temperature characteristic shows a value smaller than 0.90.

No. 24 to No. As shown in No. 37, MnCO ₃ is outside the range of 0.1-1.5 mol %. Nos. 24 and 25, where Co ₂ O ₃ is outside the range of 0.1-1.5 mol %. Nos. 26 and 27, Cr ₂ O ₃ outside the range of 0.1-1.5 mol %. 28 and 29, Nos. where SiO ₂ is outside the range of 1.0-2.5 mol %. Nos. 30 and 31, NiO outside the range of 0.1 to 2.0 mol %. Nos. 32 and 33, Ag ₂ O outside the range of 0.001-0.010 mol %. Nos. 34 and 35, Al ₂ O ₃ outside the range of 0.005-0.500 mol %. It can be seen that 36 and 37 have a limiting voltage ratio of less than 1.55 and have not achieved a temperature characteristic of 0.90 or more (incompatible).

No. 2 to which 2.40 mol % (2.5 mol % or less) of RE ₂ O ₃ (Y ₂ O ₃ ) was added. 38 achieved a limiting voltage ratio of less than 1.55 and a temperature characteristic of 0.90 or more. However, No. 2.53 mol % (more than 2.5 mol %) of RE ₂ O ₃ (Y ₂ O ₃ ) was added. 39 has a limiting voltage ratio greater than 1.55.

No. 40 to No. In No. 44, the content of two or more subcomponents does not have the preferred composition in this example (outside the composition range), and the limiting voltage ratio is less than 1.55 and the temperature characteristic is 0.90 or more. I know you won't.

As described above, the ZnO element described in this embodiment includes a sintered body containing zinc oxide as a main component and bismuth, antimony and magnesium as subcomponents. By containing 0.50 to 1.45 mol% of bismuth oxide, 1 to 2 mol% of antimony oxide, and 0.01 to 0.10 mol% of magnesium oxide in physical terms, the varistor voltage, limiting voltage ratio and temperature characteristics are balanced. voltage non-linear resistors can be provided.

In addition to these, manganese (Mn), cobalt (Co), chromium (Cr), nickel (Ni), aluminum (Al), silver (Ag), silicon (Si), boron (B), and/or By adding an additive such as a rare earth element (RE) in the preferred composition range described in this embodiment, it is possible to provide a voltage non-linear resistor with well-balanced varistor voltage, limiting voltage ratio and temperature characteristics. can.

No. described in Table 1. 15 and no. Using a sintered body of composition No. 42, a doughnut-shaped (hollow cylinder) with an outer diameter of 130 mm and an inner diameter of 50 mm, and a disk-shaped (cylindrical) with a diameter of 100 mm (both thicknesses are 20 mm). It was manufactured and a life test was performed.

The varistor voltage was 300 V/mm to 400 V/mm for all ZnO elements. As for the test method, a voltage of 85% of the varistor voltage of each ZnO element was continuously applied at a test temperature of 115° C., and changes in current values over time were measured.

FIG. 3 is a graph showing the results of a life test (hollow columnar element: 130 mm outer diameter and 50 mm inner diameter element). Moreover, FIG. 4 is a graph showing the results of a life test (cylindrical: element with a diameter of 100 mm). 3 and 4 show the rate of current change (%) against time (h).

As shown in FIGS. 3 and 4, the ZnO elements of any shape are No. The sintered body with the composition of No. 15 exhibits a substantially constant current value and is thermally stable. On the other hand, No. In the sintered body having the composition of No. 42, the current value increased sharply within several hours immediately after the start, and a thermal runaway state occurred.

From this, it can be concluded that No. 1, which has a temperature characteristic of 0.90 or more. 15 is found to be thermally stable (sufficient thermal stability). On the other hand, no. It can be seen that 42 is not thermally stable (thermal stability is not sufficient).

From this, it can be seen that by adding in the preferred composition range described in Example 1, it is possible to provide a voltage non-linear resistor with well-balanced varistor voltage, limiting voltage ratio and temperature characteristics.

No. described in Table 1. 14 and no. A disk-shaped (cylindrical) ZnO element (thickness: 15 mm) with a diameter of 50 mm was produced using a sintered body of composition No. 41, and a tolerance test and evaluation were performed. Two types of withstand voltage tests were performed: an impulse withstand voltage test in which two waves of 65 kA impulse current were applied, and a square wave withstand voltage test in which 18 waves of 2.5 kV, 2 ms square waves were applied.

No. 14 ZnO elements did not cause element breakdown or the like in any of the tests. On the other hand, No. In the ZnO element No. 41, a crack occurred after the second wave in the impulse withstand test, and a crack occurred in the sixth wave in the square wave withstand test.

From this, it was found that the ZnO element (No. 14) using the sintered body having the preferable composition range described in this example has sufficient energy withstand characteristics and can realize miniaturization of the ZnO element. . On the other hand, the ZnO element (No. 41) using a sintered body that does not have the preferred composition range described in this example does not have sufficient energy withstand characteristics, and it is not possible to realize miniaturization of the ZnO element. have understood.

As described above, according to this example, it was demonstrated that a voltage non-linear resistor in which the varistor voltage, the limiting voltage ratio and the temperature characteristics are well balanced at a high level can be provided. It was also verified that the ZnO element described in this example satisfies a sufficient level of life and withstand voltage characteristics.

In addition, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the described configurations. In addition, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

DESCRIPTION OF SYMBOLS 100... ZnO element, 110... Sintered compact, 120... Electrode, 130... Insulating layer, 210... Cylindrical sintered compact, 220... Hollow columnar sintered compact.

Claims (4)

a sintered body, electrodes formed on upper and lower surfaces of the sintered body, and insulating layers formed on side surfaces of the sintered body,
The sintered body contains zinc oxide (ZnO) as a main component, and as auxiliary components, 0.50 to 1.45 mol% of bismuth oxide (Bi2O3) and 1.0% of antimony oxide (Sb2O3) in terms of oxide. ~2.0 mol% and magnesium oxide (MgO) containing 0.02-0.06 mol% . Additives include manganese (Mn), cobalt (Co), chromium (Cr), nickel (Ni), aluminum (Al), silver (Ag), silicon (Si), boron (B), and/or rare earth elements ( RE). Additives: 0.1 to 1.5 mol% in terms of MnCO3, 0.1 to 1.5 mol% in terms of Co2O3, 0.1 to 1.5 mol% in terms of Cr2O3, 0.1 to 2.0 mol in terms of NiO %, 0.3 mol% or less in terms of B2O3, 0.005 to 0.500 mol% in terms of Al2O3, 0.001 to 0.010 mol% in terms of Ag2O, 1.0 to 2.5 mol% in terms of SiO2, 3. The voltage non-linear resistor according to claim 2, containing 2.5 mol % or less in terms of RE2O3. When the voltage when a current of 1 mA is passed through the voltage non-linear resistor is V1 mA, and the peak voltage when an impulse current of 10 kA is passed through the voltage non-linear resistor is V10 kA, the limiting voltage ratio is V10 kA/V1 mA. is less than 1.55, the voltage when a current of 1 mA is passed through the voltage non-linear resistor at 115 ° C. is V1 mA, 115 ° C., and a current of 1 mA is passed through the voltage non-linear resistor at 30 ° C. 2. The voltage non-linear resistor according to claim 1, wherein the temperature characteristic V1mA, 115° C./V1mA, 30° C. is 0.90 or more when the voltage at the time is V1 mA, 30° C.

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