JP2013251385A - Current and voltage nonlinear resistor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current and voltage nonlinear resistor excellent in a nonlinear resistance characteristic, an energy tolerance characteristic and thermal stability at high temperature.SOLUTION: A current and voltage nonlinear resistor 10 of an embodiment includes a sintered body 20 of a mixture containing zinc oxide as a main component, and at least bismuth, antimony, manganese, cobalt, nickel, and aluminum as accessory components. The mixture contains zinc oxide of ≥98 mol%, and BiOof 0.1-0.5 mol%, SbOof 0.4-0.9 mol% by converting bismuth and antimony into BiO, SbO, respectively.

Description

  Embodiments described herein relate generally to a current-voltage nonlinear resistor and a method for manufacturing the same.

  In general, an overvoltage protection device such as a lightning arrester or a surge absorber is used to protect a power system or an electronic device circuit from an abnormal voltage. The lightning arrester and surge absorber have a non-linear resistor that exhibits insulation characteristics under normal voltage and low resistance when an abnormal voltage is applied, and is effective in suppressing overvoltage.

This current-voltage non-linear resistor has, for example, zinc oxide (ZnO) as a main component, and Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , and NiO added as subcomponents thereto. Made from raw materials. The current-voltage non-linear resistor is a ceramic body formed by mixing, granulating, forming, and sintering these raw materials. An insulating layer made of an electrically insulating material is formed on the side surface of the sintered body in order to prevent flashover from the side surface during surge absorption.

  With the recent increase in power demand, there is a demand for downsizing and high performance of the equipment that constitutes the transmission and transformation equipment in order to reduce the transmission cost in the power system. A current-voltage non-linear resistor mainly composed of zinc oxide has excellent non-linear resistance characteristics and is therefore applied to a lightning arrester. By reducing the size of the current-voltage nonlinear resistor applied to the lightning arrester, the lightning arrester itself can be reduced in size. As a result, the equipment cost for configuring the transmission / transformation equipment can be reduced.

In order to reduce the size of the current-voltage nonlinear resistor, for example, the content of subcomponents such as Bi ₂ O ₃ , Co ₂ O ₃ , MnO, Sb ₂ O ₃ , NiO is limited, and ZnO is mainly used. A current-voltage nonlinear resistor in which the crystal phase of Bi ₂ O ₃ contained in the sintered body as a component is limited has been studied.

Japanese Patent Publication No. 4-25681 JP 2001-307909 A

  In order to reduce the size of a conventional lightning arrester, it is necessary to reduce the current-voltage non-linear resistor used in the lightning arrester. However, as the size of the current-voltage nonlinear resistor is reduced, the temperature rise due to Joule heat in the current-voltage nonlinear resistor after absorbing the surge energy increases.

  The current-voltage nonlinear resistor has a characteristic that the resistance value decreases as the temperature rises. When the temperature of the current-voltage nonlinear resistor increases, the leakage current increases, and thermal runaway may be caused by the commercial frequency current after absorbing the surge energy. Therefore, miniaturization of the current-voltage non-linear resistor is limited, and conventionally, the arrester cannot be sufficiently miniaturized.

  The problem to be solved by the present invention is to provide a current-voltage non-linear resistor excellent in non-linear resistance characteristics, energy withstand characteristics, and thermal stability at high temperatures.

The current-voltage nonlinear resistor of the embodiment includes a sintered body of a mixture containing zinc oxide as a main component and at least bismuth, antimony, manganese, cobalt, nickel, and aluminum as subcomponents. Then, the mixture of zinc oxide 98 mol% or more, and bismuth, antimony and converted to _{Bi 2 O 3, Sb 2 O} 3 , respectively, 0.1 to 0.5 mol% of _Bi 2 _{O 3, Sb} 2 _{O 3} is contained in an amount of 0.4 to 0.9 mol%.

It is a figure which shows the cross section of the current-voltage nonlinear resistor 10 of embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a cross section of a current-voltage nonlinear resistor 10 according to an embodiment.

As shown in FIG. 1, the current-voltage nonlinear resistor 10 of the embodiment is mainly composed of zinc oxide (ZnO), and at least bismuth (Bi), antimony (Sb), manganese (Mn), A sintered body 20 of a mixture containing cobalt (Co), nickel (Ni), and aluminum (Al) is provided. Mixture of zinc oxide 98 mol% or more, and bismuth, antimony in terms of _{Bi 2 O 3, Sb 2 O} 3, 0.1~0.5mol% of _Bi 2 _{O 3,} the _Sb 2 _{O 3} 0. 4 to 0.9 mol% is contained.

  The current-voltage nonlinear resistor 10 includes an insulating layer 30 that covers the side surface of the sintered body 20 and electrodes 40 formed on the upper and lower surfaces of the sintered body 20.

In the mixture, manganese, cobalt, nickel, and aluminum, which are subcomponents other than bismuth and antimony, are converted into MnO, Co ₂ O ₃ , NiO, and Al ³⁺ , respectively, and MnO is 0.05 to 0.2 mol%, Co the ₂ O _{3 0.1~0.3mol%,} NiO of 0.1~0.25mol%, preferably contains 0.002～0.008Mol% of ^{Al 3+.}

  Next, the reason for limiting the content of each composition component of the mixture will be described.

  When the content of zinc oxide is smaller than 98%, the insulating component inside the sintered body 20 increases, the energy resistance is lowered, and the thermal stability is deteriorated. Therefore, the content of zinc oxide is set to 98 mol% or more.

Bi ₂ O ₃ is a component that exists at the grain boundary of zinc oxide, which is the main component, and develops non-linear resistance characteristics. When the content of Bi ₂ O ₃ is less than 0.1 mol%, it is not possible to sufficiently obtain the effect of developing this non-linear resistance characteristic. On the other hand, when the content of Bi ₂ O ₃ is larger than 0.5 mol%, the nonlinear resistance characteristic is deteriorated.

Therefore, in terms of bismuth _Bi 2 _{O 3,} it was 0.1 to 0.5 mol% of the content of _Bi 2 _{O 3.} Furthermore, more preferable range of the content of _Bi 2 _{O 3} is 0.3~0.45mol%.

Sb ₂ O ₃ is a component that has the effect of suppressing the growth of zinc oxide particles during sintering by forming zinc oxide and spinel particles and making them uniform, and improving the non-linear resistance characteristics. . When the content of Sb ₂ O ₃ is smaller than 0.4 mol%, the effect of improving the nonlinear resistance characteristic cannot be sufficiently obtained. On the other hand, when the content of Sb ₂ O ₃ is larger than 0.9 mol%, the insulating component inside the sintered body 20 is increased, the energy resistance is lowered, and the thermal stability is deteriorated.

Therefore, in terms of antimony _Sb 2 _{O 3,} it was 0.4～0.9Mol% content of _Sb 2 _{O 3.} Furthermore, more preferable range of the content of _Sb 2 _{O 3} is 0.5~0.9mol%.

  MnO is an effective component in order to largely improve the non-linear resistance characteristic by mainly dissolving in spinel particles. When the content of MnO is smaller than 0.05 mol%, the effect of improving the non-linear resistance characteristic cannot be sufficiently obtained. On the other hand, when the content of MnO is larger than 0.2 mol%, the electrical insulating component inside the sintered body 20 increases, the energy resistance is lowered, and the thermal stability is deteriorated.

  Therefore, manganese is converted into MnO, and the content of MnO is set to 0.05 to 0.2 mol%. Moreover, the more preferable range of content of MnO is 0.05-0.15 mol%.

Co ₂ O ₃ is an effective component for largely improving the non-linear resistance characteristic by mainly dissolving in spinel particles. When the content of Co ₂ O ₃ is smaller than 0.1 mol%, the effect of improving the non-linear resistance characteristic cannot be sufficiently obtained. On the other hand, when the content of Co ₂ O ₃ is larger than 0.3 mol%, the electrical insulation component inside the sintered body 20 increases, the energy resistance is lowered, and the thermal stability is deteriorated.

Therefore, in terms of cobalt to _Co 2 _{O 3,} it was 0.1～0.3Mol% content of _Co 2 _{O 3.} Furthermore, more preferable range of the content of _Co 2 _{O 3} is 0.1~0.25mol%.

  NiO is an effective component mainly for solid solution in spinel particles and greatly improving the non-linear resistance characteristics. When the content of NiO is smaller than 0.1 mol%, the effect of improving the non-linear resistance characteristic cannot be obtained sufficiently. On the other hand, when the content of NiO is larger than 0.25 mol%, the electrical insulating component inside the sintered body 20 increases, the energy resistance is lowered, and the thermal stability is deteriorated.

  Therefore, nickel is converted into NiO, and the content of NiO is set to 0.1 to 0.25 mol%.

Al ³⁺ is an effective component for mainly dissolving in ZnO particles to lower the resistance of ZnO particles and greatly improve non-linear resistance characteristics. When the content of Al ³⁺ is smaller than 0.002 mol%, the effect of improving the non-linear resistance characteristic cannot be sufficiently obtained. On the other hand, when the content of Al ³⁺ is larger than 0.008 mol%, the non-linear resistance characteristic is deteriorated.

Therefore, in terms of aluminum to ^{Al 3+,} it was 0.002～0.008Mol% content of ^{Al 3+.}

The mixture is at least one rare earth selected from yttrium (Y), europium (Eu), erbium (Er), thulium (Tm), gadolinium (Gd), dysprosium (Dy), holmium (Ho), and ytterbium (Yb). It is preferable that the element R is contained in an amount of 0.5 mol% or less in terms of R ₂ O ₃ .

Here, by including the rare earth element R described above in terms of R ₂ O ₃ in an amount of 0.5 mol% or less, excellent non-linear resistance characteristics and thermal stability without increasing the insulating component inside the sintered body Can be obtained. On the other hand, if the rare earth element R described above is contained in an amount exceeding 0.5 mol% in terms of R ₂ O ₃ , the non-linear resistance characteristics are deteriorated.

The lower limit of the content of R ₂ O ₃ mentioned above, in order to exhibit the above effects by the addition of rare earth element R described above, it is preferable to 0.005 mol%.

  Here, the average particle size of the mixture is preferably 0.4 μm or less. By making the average particle size of the mixture 0.4 μm or less, the growth of zinc oxide particles in the firing process proceeds uniformly, and there is no local bias of the current path. Therefore, the current-voltage nonlinear resistor 10 having excellent non-linear resistance characteristics, energy withstand characteristics, and thermal stability can be obtained.

  On the other hand, if the average particle size of the mixture exceeds 0.4 μm, local bias of the current-carrying path occurs during the growth of zinc oxide particles in the firing process, and excellent non-linear resistance characteristics, energy resistance characteristics and heat Stability cannot be obtained. In addition, although the average particle diameter of a mixture is so preferable that it is small, the minimum value of the average particle diameter of a mixture will be about 0.05 micrometer by the limit on preparation at the time of grind | pulverizing a mixture.

  The standard deviation based on the particle size distribution of the mixture is preferably 75% or less of the average particle size of the mixture. That is, it is preferable that the standard deviation based on the particle size distribution of the mixture is divided by the average particle size of the mixture and the value expressed as a percentage is 75% or less.

  By setting the standard deviation based on the particle size distribution of the mixture to 75% or less of the average particle size of the mixture, the raw materials are uniformly dispersed, and the growth of zinc oxide particles in the firing process proceeds uniformly. The particle size of the zinc oxide particles is made uniform. As a result, it is possible to obtain the current-voltage nonlinear resistor 10 having excellent nonlinear resistance characteristics, energy withstand characteristics, and thermal stability.

  On the other hand, when the standard deviation based on the particle size distribution of the mixture exceeds 75% of the average particle size of the mixture, the particle size of the zinc oxide particles in the sintered body 20 becomes difficult to be made uniform, and excellent non-linear resistance characteristics, Energy tolerance characteristics and thermal stability cannot be obtained.

  The average particle diameter of the mixture is measured using, for example, a laser diffraction / scattering particle size distribution measuring apparatus. Moreover, the average particle diameter of the above-mentioned mixture is an average particle diameter in the median diameter. The standard deviation is determined based on the particle size distribution of the mixture measured by the above particle size distribution measuring apparatus.

  Here, the standard deviation based on the particle size distribution of the zinc oxide particles in the sintered body 20 is preferably 15% or less of the average particle diameter of the zinc oxide particles. That is, it is preferable that the standard deviation based on the particle size distribution of the zinc oxide particles in the sintered body 20 is divided by the average particle diameter of the zinc oxide particles and the value expressed as a percentage is 15% or less.

  By setting the standard deviation based on the particle size distribution of the zinc oxide particles in the sintered body 20 to 15% or less of the average particle diameter of the zinc oxide particles, the particle diameter of the zinc oxide is made uniform. The microstructure is homogenized. Therefore, local bias of the conductive path is eliminated, and excellent non-linear resistance characteristics, energy resistance characteristics and thermal stability can be obtained.

  The average particle diameter of the zinc oxide particles in the sintered body 20 is obtained by cutting out the inside of the sintered body 20, polishing the cut sample, and observing the reflected electron image with a scanning electron microscope (SEM). . Specifically, by cutting out a plurality of samples, and taking several SEM photographs with different fields of view for each sample, for example, at a magnification of 1000 times, for example, measuring the particle size of 500 to 1000 zinc oxide particles The average particle diameter of the zinc oxide particles in the sintered body 20 can be determined.

  As described above, the standard deviation is calculated based on the particle size distribution of the zinc oxide particles in the sintered body 20 obtained from the measured average particle diameter. In addition, for example, zinc oxide particles, spinel particles, bismuth oxide layers, pores, and the like can be identified by the color of an observation photograph in a reflected electron image.

The standard deviation based on the particle size distribution of the spinel particles mainly composed of Zn ₇ Sb ₂ O ₁₂ in the sintered body 20 is preferably 30% or less of the average particle diameter of the spinel particles. That is, it is preferable that the standard deviation based on the particle size distribution of the spinel particles is divided by the average particle size of the spinel particles, and the value expressed as a percentage is 30% or less.

Spinel particles (Zn ₇ Sb ₂ O ₁₂ ) formed mainly from zinc oxide and antimony trioxide (Sb ₂ O ₃ ) have the property of suppressing the growth of zinc oxide particles during the firing process. However, when a large number of spinel particles, which are insulators, are locally present, or when the size of the spinel particles is biased, the energization path is limited and the energy resistance is reduced.

  Therefore, as described above, by making the standard deviation based on the particle size distribution of the spinel particles 30% or less of the average particle size of the spinel particles, the zinc oxide particle size in the sintered body 20 is made uniform and the spinel. The particle size deviation is reduced. Therefore, the current-voltage non-linear resistor 10 having excellent non-linear resistance characteristics, energy withstand characteristics and thermal stability can be obtained.

  Here, the insulating layer 30 covering the side surface of the sintered body 20 is made of, for example, an inorganic insulating material such as a glass frit which is an electrically insulating material. The insulating layer 30 is formed by, for example, applying or spraying the above-described electrical insulating material to the side surface of the sintered body 20 and performing heat treatment. The insulating layer 30 is preferably formed to have a thickness of about 0.05 to 0.2 mm from the viewpoint of insulating performance and mechanical strength.

  The electrodes 40 formed on the upper and lower surfaces of the sintered body 20 are made of a material such as aluminum or silver having electrical conductivity, for example. The electrode 40 is formed on the upper and lower surfaces of the sintered body 20 by, for example, spraying the above-described conductive material. The thickness of the electrode 40 is preferably about 0.05 to 0.15 mm from the viewpoint of adhesiveness with the sintered body 20.

  Next, a method for manufacturing the current-voltage nonlinear resistor 10 according to the embodiment will be described.

First, it contains 98 mol% or more of zinc oxide as a main component, and Bi ₂ O ₃ , Sb ₂ O ₃ , MnO, Co ₂ O ₃ , NiO, bismuth, antimony, manganese, cobalt, nickel, and aluminum as subcomponents, respectively. Converted to Al ³⁺ , Bi ₂ O ₃ is 0.1 to 0.5 mol%, Sb ₂ O ₃ is 0.4 to 0.9 mol%, MnO is 0.05 to 0.2 mol%, Co ₂ O ₃ Is 0.1 to 0.3 mol%, NiO is 0.1 to 0.25 mol%, and Al3 ⁺ is 0.002 to 0.008 mol% to prepare a mixture.

  Subsequently, the prepared mixture and an organic solvent adjusted so that the content of the mixture is 30 to 60% by weight are charged into a wet pulverizer. For example, the average particle size of the mixture is 0.4 μm or less. The mixture is mixed while being pulverized to prepare a slurry. As the organic solvent, for example, a mixture of water and an organic binder such as polyvinyl alcohol is used.

  Here, as the wet pulverization apparatus, for example, a circulation type apparatus using zirconia beads having a diameter of 0.05 to 0.3 mm is used. Further, the bead filling rate in the vessel in the wet pulverization apparatus can be 35 to 95%, the peripheral speed of the stirring rotor can be 500 to 1500 rpm, and the circulation flow rate can be operated at 5 to 50 L / min.

  Subsequently, the produced slurry is sprayed and granulated by a rotating disk method or a pressure nozzle method to produce a granulated powder. Here, the particle size of the granulated powder is preferably 70 to 130 μm. The particle size at this time is measured using the above-mentioned laser diffraction / scattering particle size distribution measuring device or the like. Here, the reason why the particle size of the granulated powder is preferably 70 to 130 μm is that moldability is good and a dense molded body can be obtained.

  The obtained granulated powder is molded into a columnar shape by, for example, a hydraulic press molding machine to produce a molded body.

  Subsequently, the molded body is heated to a first temperature of 350 to 500 ° C., and maintained at this temperature for 1 to 3 hours, for example, to degrease the organic solvent.

  Next, the molded body is heated to a second temperature of 900 to 1300 ° C. and maintained at this temperature for 2 hours or longer, for example, and fired. The firing is performed, for example, by using a tunnel-type continuous furnace and placing the compact in a refractory container such as alumina or mullite. Moreover, it is preferable that the heating rate from 1st temperature to 2nd temperature is 50-200 degreeC / hour from a viewpoint of the temperature uniformity in a to-be-baked thing, and a baking process lead time.

  After the maintenance time of the second temperature has elapsed, the fired molded body is cooled. In addition, when cooling, it is preferable to make the cooling rate in the temperature of 750 degrees C or less into 25-100 degrees C / hour. Through this cooling step, the sintered body 20 is obtained.

  After cooling, the above-described inorganic insulator is applied or sprayed onto the side surface of the sintered body 20 and heat-treated at a temperature of 300 to 500 ° C. for 1 to 5 hours to form the insulating layer 30.

  Further, the upper and lower end surfaces of the sintered body 20 are polished, and the electrode 40 is formed on the polished surface by, for example, spraying the above-described conductive material.

  In addition, the order which performs the process of forming the insulating layer 30, and the process of forming the electrode 40 is not specifically limited, Any may be performed first.

  Thus, the current-voltage nonlinear resistor 10 is produced through the above-described steps.

  As described above, according to the current-voltage nonlinear resistor 10 of the embodiment, excellent nonlinear resistance characteristics, energy withstand characteristics, and thermal stability can be obtained.

  Next, it will be specifically described below that the current-voltage nonlinear resistor 10 of the embodiment has excellent characteristics.

(Influence of the composition of the mixture)
Here, ZnO is the main component, and subcomponents are bismuth (Bi), antimony (Sb), manganese (Mn), cobalt (Co), nickel (Ni), aluminum (Al) Bi ₂ O ₃ , Sb ₂ O. ₃ , the influence of the composition of the mixture containing MnO, Co ₂ O ₃ , NiO, and Al ³⁺ on the characteristics of the current-voltage nonlinear resistor will be described.

  Table 1 shows the composition of the mixture in Samples 1 to 14. In Table 1, the composition of the sample marked with * is outside the range of the composition according to the present invention, and the sample marked with * is a comparative example (the same applies hereinafter). Moreover, content shown in Table 1 is mol%.

  A mixture adjusted to have the composition shown in Table 1, and water and an organic binder adjusted so that the content of the mixture was 40% by weight were put into a circulation type wet pulverizer. In the wet pulverizer, the average particle size of the mixture is adjusted to 0.4 μm by adjusting the particle size of the zirconia beads, the bead filling rate in the vessel, the peripheral speed of the stirring rotor, the circulation flow rate, and the mixing time. Grinding was performed. A uniformly mixed slurry was obtained by pulverization and mixing in the wet pulverizer.

  Here, the average particle diameter of the mixture was measured using a laser diffraction / scattering particle size distribution measuring apparatus. Moreover, this average particle diameter is an average particle diameter in a median diameter.

  Subsequently, this slurry was spray-granulated with a spray dryer so that the particle size became 80 μm. The obtained granulated powder was formed into a cylindrical shaped body having a diameter of 40 mm and a thickness of 40 mm by a hydraulic press molding machine.

  Subsequently, the molded body was heated to a temperature of 500 ° C. and maintained at this temperature for 2 hours to degrease the organic binder as an organic solvent.

  Next, the molded body was heated to a temperature of 1050 ° C. and maintained at this temperature for 3 hours and fired. The firing was performed by using a tunnel-type continuous furnace and placing the compact in a mullite refractory container. Moreover, the heating rate until it became each baking temperature of 500 to 1050 degreeC was 100 degreeC / hour.

  After the maintenance time of each firing temperature elapsed, the fired molded body was cooled. In addition, the cooling rate at the time of cooling in the temperature of 750 degrees C or less was 100 degrees C / hour. Through this cooling process, a sintered body was obtained.

  Subsequently, glass frit was applied to the side surface of the sintered body, which was a cooled molded body, and heat-treated at a temperature of 500 ° C. for 2 hours to form an insulating layer. Furthermore, the upper and lower end surfaces of the sintered body were polished, and aluminum was sprayed on the polished surface to form an electrode to obtain a current-voltage nonlinear resistor.

For the obtained current-voltage nonlinear resistors according to Sample 1 to Sample 14, the non-linearity coefficient (V _{10 kA} / V _{1 mA} ), energy tolerance and resistance leakage current (I _R ) were evaluated.

In evaluating the non-linear resistance characteristics, first, a varistor voltage (V _{1 mA} ), which is a voltage when a current of 1 mA of commercial frequency is applied, was measured according to JEC0202-1994. Next, the varistor voltage (V _{1 mA} ) and the voltage (V _{10 kA} ) when an 8 × 20 μs impulse current was applied at 10 kA were measured, and the ratio (V _{10 kA} / V _{1 mA} ) was evaluated as a nonlinear coefficient. . It shows that the nonlinear resistance characteristic is excellent, so that the value of this nonlinear coefficient is small.

In the evaluation of energy tolerance, a commercial frequency voltage (50 Hz) that is 1.3 times the varistor voltage (V _{1 mA} ) is continuously applied, and the energy value (J / cc) absorbed until breakdown is measured, and this energy value ( J / cc) was evaluated for energy tolerance. Here, until breaking refers to until the AE detector detects that a crack has occurred in the current-voltage nonlinear resistor. The larger the energy value (J / cc), the better the energy withstand characteristics.

In the evaluation of thermal stability, resistance leakage current (I _R ) was measured when an AC voltage of 90% of the varistor voltage (V _{1 mA} ) was applied in a thermostatic chamber at 200 ° C under atmospheric pressure. The thermal stability was evaluated based on the resistance leakage current (I _R ). The resistance leakage current (I _R ) is a current resulting from a resistance component when the electrical characteristics at the grain boundary of the zinc oxide element are qualitatively expressed using an electrical equivalent circuit. It indicates that the value of the resistive leakage current (I _R) is excellent in thermal stability enough at high temperatures small.

  In each of the above-described evaluation tests, 10 pieces of each current-voltage non-linear resistor were produced, tested for 10 pieces, and evaluated using the average value (the same applies to other tests below). ).

Table 2 shows the measurement results of the non-linearity coefficient (V _{10 kA} / V _{1 mA} ), energy tolerance and resistance leakage current (I _R ) in the current-voltage nonlinear resistors according to Sample 1 to Sample 14. ing.

As shown in Table 2, in the current-voltage nonlinear resistors according to Sample 2 to Sample 4, Sample 7, Sample 8, and Sample 10, the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) is 1. It was found that it was smaller than 7, the energy withstand was larger than 1000 J / cc, and the resistance leakage current (I _R ) was smaller than 3.0 mA. That is, it was found that the current-voltage nonlinear resistors according to these samples are excellent in all of the nonlinear resistance characteristics, the energy withstand characteristics, and the thermal stability.

  On the other hand, none of the current-voltage nonlinear resistors of the comparative examples were excellent in all of the nonlinear resistance characteristics, energy withstand characteristics, and thermal stability.

Here, the non-linearity coefficient (V _{10 kA} / V _{1 mA} ) is 1.7, the energy resistance is 1000 J / cc, and the resistance leakage current (I _R ) is 3.0 mA. Even if the same test evaluation is performed on the non-linear resistance characteristics, energy resistance characteristics and thermal stability using general materials used as linear resistors, these evaluation criteria are superior or inferior. This is because it was considered to be a reasonable value in evaluating

That is, even when considering the case where the same test evaluation is performed in the non-linear resistance characteristic, the energy withstand characteristic and the thermal stability using a general material used as a current-voltage non-linear resistor, When the linearity coefficient (V _{10 kA} / V _{1 mA} ) is smaller than 1.7, it can be evaluated that the nonlinear resistance characteristic is excellent. Further, when the energy resistance is greater than 1000 J / cc, it can be evaluated that the energy resistance characteristics are excellent. Furthermore, when the resistance leakage current (I _R ) is smaller than 3.0 mA, it can be evaluated that the thermal stability at high temperature is excellent.

(Effect of addition of rare earth elements)
Here, the effect of the addition of rare earth elements on the characteristics of the current-voltage nonlinear resistor will be described.

  Table 3 shows the compositions of the mixtures in Sample 15 to Sample 41 to which rare earth elements were added. The step of producing the current-voltage nonlinear resistor using these mixtures was the same as the step of producing the current-voltage nonlinear resistor when examining the influence of the composition of the mixture described above. Samples 15 to 41 are samples obtained by adding rare earth elements based on the sample 3 described above as a basic composition.

  The current-voltage nonlinear resistors according to Sample 15 to Sample 41 were evaluated for nonlinear resistance characteristics and thermal stability. Note that the experimental conditions and experimental methods in the evaluation of the non-linear resistance characteristics and the thermal stability were the same as the experimental conditions and experimental methods for examining the influence of the composition of the mixture described above.

Table 4 shows the measurement results of the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) and the resistance leakage current (I _R ) in the current-voltage nonlinear resistors according to Sample 15 to Sample 41.

As shown in Table 4, Sample 15 to Sample 18, Sample 21 to Sample 22, Sample 24 to Sample 25, Sample 27 to Sample 28, Sample 30 to Sample 31, Sample 33 to Sample 34, Sample 36 to Sample 37, Sample In all of the current-voltage nonlinear resistors according to 39 to 40, the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) is smaller than 1.7, and the resistance leakage current (I _R ) is smaller than 3.0 mA. I found it smaller. That is, it was found that the current-voltage nonlinear resistors according to these samples are excellent in both nonlinear resistance characteristics and thermal stability. Although not shown in Table 4, the energy tolerance of these samples exceeded 1000 J / cc.

On the other hand, in the current-voltage non-linear resistor of the comparative example, the non-linearity coefficient (V _{10 kA} / V _{1 mA} ) is larger than 1.7, and the resistance leakage current (I _R ) is 3 for most samples. It exceeded 0.0 mA. That is, none of the current-voltage nonlinear resistors of the comparative examples were excellent in both nonlinear resistance characteristics and thermal stability.

(Influence of particle size distribution of zinc oxide particles in sintered body)
Here, the influence of the standard deviation based on the particle size distribution of the zinc oxide particles in the sintered body on the characteristics of the current-voltage nonlinear resistor will be described.

  Using the mixture having the composition of Sample 3 described above, water and an organic binder, which were adjusted so that the content of the mixture was 40% by weight, were put into a circulation type wet pulverizer. Then, in a wet pulverizer, mixtures having different particle size conditions were prepared by varying the particle size of zirconia beads, the bead filling rate in the vessel, the peripheral speed of the stirring rotor, the circulation flow rate, and the mixing time.

  And the current-voltage nonlinear resistor which concerns on the sample 42-sample 46 shown in Table 5 was produced using each mixture. In addition, the process for producing the current-voltage nonlinear resistor after producing the mixture was the same as the process for producing the current-voltage nonlinear resistor in examining the influence of the composition of the mixture described above.

About each produced sample, the standard deviation ((sigma) ₁ ) based on the average particle diameter ((micro | micron | mu) ₁ ) of the zinc oxide particle in a sintered compact, and the particle size distribution of the zinc oxide particle in a sintered compact was measured. Here, the above-described sample 3 was also evaluated.

Here, the average particle diameter (μ ₁ ) of the zinc oxide particles in the sintered body is determined by cutting out the inside of the sintered body, mirror-polishing the cut out sample, and analyzing the reflected electron image with a scanning electron microscope (SEM). Obtained by observation. Specifically, three samples were cut out for each of the samples 3 and 42 to 46, and five SEM photographs were taken at different magnifications for each of the cut out samples at a magnification of 1000 times, and approximately 3000 times. The average particle size was determined by measuring the particle size of each zinc oxide particle. The standard deviation (σ ₁ ) was calculated based on the particle size distribution of the zinc oxide particles in the sintered body obtained from the measured average particle size.

  The current-voltage nonlinear resistors according to Samples 42 to 46 were evaluated for nonlinear resistance characteristics, energy withstand characteristics, and thermal stability. Note that the experimental conditions and experimental methods in the evaluation of the non-linear resistance characteristics, the energy withstand characteristics, and the thermal stability were the same as the experimental conditions and experimental methods for investigating the influence of the composition of the mixture described above.

Table 5 shows the zinc oxide particle size, nonlinearity coefficient (V _{10 kA} / V _{1 mA} ), and resistance leakage current (I _R ) in the current-voltage nonlinear resistors according to Sample 3 and Samples 42 to 46. ) Measurement results are shown.

As shown in Table 5, in Sample 3, Sample 42, and Sample 43, the standard deviation (σ ₁ ) based on the particle size distribution of the zinc oxide particles in the sintered body is the average particle size (μ ₁ ) of the zinc oxide particles. It was 15% or less. Moreover, in the current-voltage nonlinear resistors according to these samples, the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) is smaller than 1.7, the energy withstand is larger than 1000 J / cc, and the resistance leakage leaks. It was found that the current (I _R ) was smaller than 3.0 mA. That is, it was found that the current-voltage nonlinear resistors according to these samples are excellent in all of the nonlinear resistance characteristics, the energy withstand characteristics, and the thermal stability.

On the other hand, in the current-voltage non-linear resistor of the comparative example in which the value (percentage) of σ ₁ / μ ₁ exceeds 15%, all of the non-linear resistance characteristics, the energy withstand characteristics, and the thermal stability are excellent. There wasn't.

(Effect of average particle size of spinel particles in sintered body)
Here, the influence of the standard deviation based on the particle size distribution of the spinel particles containing Zn ₇ Sb ₂ O ₁₂ as a main component in the sintered body on the characteristics of the current-voltage nonlinear resistor will be described.

  Using the mixture having the composition of Sample 3 described above, water and an organic binder, which were adjusted so that the content of the mixture was 40% by weight, were put into a circulation type wet pulverizer. Then, in a wet pulverizer, mixtures having different particle size conditions were prepared by varying the particle size of zirconia beads, the bead filling rate in the vessel, the peripheral speed of the stirring rotor, the circulation flow rate, and the mixing time.

  And the current-voltage nonlinear resistor which concerns on the sample 47-sample 51 shown in Table 6 was produced using each mixture. In addition, the process for producing the current-voltage nonlinear resistor after producing the mixture was the same as the process for producing the current-voltage nonlinear resistor in examining the influence of the composition of the mixture described above.

For fabricated sample, spinel composed mainly of average particle diameter (mu ₂₎ and _Zn 7 _Sb 2 _{O 12} in the sintered body of the spinel grains, whose chief constituent _Zn 7 _Sb 2 _{O 12} in the sintered body The standard deviation (σ ₂ ) based on the particle size distribution of the particles was measured. Here, the above-described sample 3 was also evaluated.

Here, the average particle diameter (μ ₂ ) of the spinel particles mainly composed of Zn ₇ Sb ₂ O ₁₂ in the sintered body is cut out from the inside of the sintered body, the cut sample is mirror-polished, and a scanning type is obtained. This was determined by observing the reflected electron image with an electron microscope (SEM). Specifically, three samples were cut out for each of Sample 3 and Sample 47 to Sample 51, and five SEM photographs were taken at different magnifications for each of the cut out samples at a magnification of 1000 times, and approximately 3000 times. The average particle size was determined by measuring the particle size of the individual spinel particles. Further, the standard deviation (σ ₂ ) was calculated based on the particle size distribution of spinel particles containing Zn ₇ Sb ₂ O ₁₂ as a main component in the sintered body obtained from the measured average particle diameter.

  The current-voltage nonlinear resistors according to Sample 47 to Sample 51 were evaluated for nonlinear resistance characteristics, energy tolerance characteristics, and thermal stability. Note that the experimental conditions and experimental methods in the evaluation of the non-linear resistance characteristics, the energy withstand characteristics, and the thermal stability were the same as the experimental conditions and experimental methods for investigating the influence of the composition of the mixture described above.

Table 6 shows the particle size, nonlinearity coefficient (V _{10 kA} / V _{1 mA} ), and resistance leakage current (I _R ) of the spinel particles in the current-voltage nonlinear resistors according to Sample 3 and Sample 47 to Sample 51. The measurement results are shown.

As shown in Table 6, in Sample 3, Sample 47, and Sample 48, the standard deviation (σ ₂ ) based on the particle size distribution of the spinel particles mainly composed of Zn ₇ Sb ₂ O ₁₂ in the sintered body is the spinel particles. The average particle size (μ ₂ ) was 30% or less. Moreover, in the current-voltage nonlinear resistors according to these samples, the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) is smaller than 1.7, the energy withstand is larger than 1000 J / cc, and the resistance leakage leaks. It was found that the current (I _R ) was smaller than 3.0 mA. That is, it was found that the current-voltage nonlinear resistors according to these samples are excellent in all of the nonlinear resistance characteristics, the energy withstand characteristics, and the thermal stability.

On the other hand, in the current-voltage non-linear resistor of the comparative example in which the value (percentage) of σ ₂ / μ ₂ exceeds 30%, all of the non-linear resistance characteristic, the energy resistance characteristic and the thermal stability are excellent. There wasn't.

(Influence of the average particle size of the mixture)
Here, the influence of the average particle size of the mixture on the non-linear resistance characteristic for constituting a current-voltage non-linear resistor sintered body will be described.

  Using the mixture having the composition of Sample 3 described above, water and an organic binder, which were adjusted so that the content of the mixture was 40% by weight, were put into a circulation type wet pulverizer. Then, four types of slurries were obtained by varying the particle diameter of zirconia beads, the bead filling rate in the vessel, the peripheral speed of the stirring rotor, the circulation flow rate, and the mixing time in a wet pulverizer.

  In addition, it evaluated also about the slurry at the time of producing a current-voltage nonlinear resistor using the sample 3 mentioned above. That is, here, five types of slurry were evaluated.

  The average particle size was measured for these five types of slurries. The average particle size was measured using a laser diffraction / scattering type particle size distribution measuring apparatus. Moreover, this average particle diameter is an average particle diameter in a median particle diameter.

  And the current-voltage nonlinear resistor which concerns on the sample 52-sample 55 shown in Table 7 was produced using each slurry. In addition, the process for producing the current-voltage nonlinear resistor after producing the mixture was the same as the process for producing the current-voltage nonlinear resistor in examining the influence of the composition of the mixture described above.

  The current-voltage nonlinear resistors according to Sample 52 to Sample 55 were evaluated for nonlinear resistance characteristics, energy withstand characteristics, and thermal stability. Note that the experimental conditions and experimental methods in the evaluation of the non-linear resistance characteristics, the energy withstand characteristics, and the thermal stability were the same as the experimental conditions and experimental methods for investigating the influence of the composition of the mixture described above.

Table 7 shows the measurement results of the average particle diameters of the mixtures according to Sample 3 and Samples 52 to 55, and the particle diameters of the spinel particles in the current-voltage nonlinear resistors according to Sample 3 and Samples 52 to 55. Measurement results of the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) and the resistance leakage current (I _R ) are shown.

As shown in Table 7, in Sample 3 and Sample 52, the average particle size of the mixture was 0.4 μm or less. Moreover, in the current-voltage nonlinear resistors according to these samples, the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) is smaller than 1.7, the energy withstand is larger than 1000 J / cc, and the resistance leakage leaks. It was found that the current (I _R ) was smaller than 3.0 mA. That is, it was found that the current-voltage nonlinear resistors according to these samples are excellent in all of the nonlinear resistance characteristics, the energy withstand characteristics, and the thermal stability.

  On the other hand, none of the current-voltage nonlinear resistors of the comparative examples in which the average particle size of the mixture exceeded 0.4 μm was excellent in all of the nonlinear resistance characteristics, energy resistance characteristics and thermal stability.

(Effect of standard deviation based on the particle size distribution of the mixture)
Here, the influence that the standard deviation based on the particle size distribution of the mixture for constituting the current-voltage nonlinear resistor sintered body has on the nonlinear resistance characteristics will be described.

  Using the mixture having the composition of Sample 3 described above, water and an organic binder, which were adjusted so that the content of the mixture was 40% by weight, were put into a circulation type wet pulverizer. Then, in the wet pulverizer, adjust the particle size of the zirconia beads, the bead filling rate in the vessel, the peripheral speed of the stirring rotor, the circulation flow rate, and the mixing time, and pulverize so that the average particle size of the mixture becomes 0.4 μm. And five types of slurries were obtained.

  In addition, it evaluated also about the slurry at the time of producing a current-voltage nonlinear resistor using the sample 3 mentioned above. That is, here, six types of slurry were evaluated.

  Here, the average particle diameter of the mixture was measured using a laser diffraction / scattering particle size distribution measuring apparatus. Moreover, this average particle diameter is an average particle diameter in a median particle diameter. Moreover, the standard deviation was calculated | required based on the particle size distribution of the mixture measured with the above-mentioned particle size distribution measuring apparatus.

  And using each slurry, the current-voltage nonlinear resistor which concerns on the sample 56-the sample 60 shown in Table 8 was produced. In addition, the process for producing the current-voltage nonlinear resistor after producing the mixture was the same as the process for producing the current-voltage nonlinear resistor in examining the influence of the composition of the mixture described above.

  The current-voltage nonlinear resistors according to Sample 56 to Sample 60 were evaluated for nonlinear resistance characteristics, energy tolerance characteristics, and thermal stability. Note that the experimental conditions and experimental methods in the evaluation of the non-linear resistance characteristics, the energy withstand characteristics, and the thermal stability were the same as the experimental conditions and experimental methods for investigating the influence of the composition of the mixture described above.

Table 8 shows the average particle size and standard deviation of the mixtures according to sample 3 and sample 56 to sample 60, and the particle size of spinel particles in the current-voltage nonlinear resistor according to sample 3 and sample 56 to sample 60. Measurement results of the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) and the resistance leakage current (I _R ) are shown.

As shown in Table 8, in Sample 3, Sample 56, and Sample 57, the standard deviation (σ ₃ ) based on the particle size distribution of the mixture was 75% or less of the average particle size (μ ₃ ) of the mixture. Moreover, in the current-voltage nonlinear resistors according to these samples, the nonlinearity coefficient (V _{10 kA} / V _{1 mA} ) is smaller than 1.7, the energy withstand is larger than 1000 J / cc, and the resistance leakage leaks. It was found that the current (I _R ) was smaller than 3.0 mA. That is, it was found that the current-voltage nonlinear resistors according to these samples are excellent in all of the nonlinear resistance characteristics, the energy withstand characteristics, and the thermal stability.

This is considered to be a result obtained by setting the σ ₃ / μ ₃ to 75% or less so that the raw material is uniformly dispersed and the particle size of the zinc oxide particles in the sintered body is made uniform. .

On the other hand, in the current-voltage nonlinear resistor of the comparative example in which the value (percentage) of σ ₃ / μ ₃ exceeds 75%, all of the nonlinear resistance characteristics, energy withstand characteristics, and thermal stability are excellent. There wasn't.

  According to the embodiments described above, it is possible to obtain excellent non-linear resistance characteristics, energy withstand characteristics, and thermal stability at high temperatures.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Current-voltage nonlinear resistor, 20 ... Sintered body, 30 ... Insulating layer, 40 ... Electrode.

Claims (6)

A current-voltage nonlinear resistor comprising a sintered body of a mixture containing zinc oxide as a main component and at least bismuth, antimony, manganese, cobalt, nickel, and aluminum as subcomponents,
Wherein the mixture, the zinc oxide 98 mol% or more, and bismuth, antimony and converted to _{Bi 2 O 3, Sb 2 O} 3 , respectively, 0.1 to 0.5 mol% of _Bi 2 _{O 3,} the _Sb 2 _{O 3} A current-voltage non-linear resistor comprising 0.4 to 0.9 mol%. The mixture is at least one rare earth element selected from yttrium (Y), europium (Eu), erbium (Er), thulium (Tm), gadolinium (Gd), dysprosium (Dy), holmium (Ho), and ytterbium (Yb). the _R, claim 1 of the current in terms of R 2 _{O 3,} characterized in that it comprises less 0.5 mol% - voltage nonlinear resistor.   The current-voltage nonlinear resistor according to claim 1 or 2, wherein a standard deviation based on a particle size distribution of the zinc oxide particles in the sintered body is 15% or less of an average particle size of the zinc oxide particles. The standard deviation based on the particle size distribution of spinel particles mainly composed of Zn ₇ Sb ₂ O ₁₂ in the sintered body is 30% or less of the average particle diameter of the spinel particles. The current-voltage nonlinear resistor according to any one of the above.   5. The current-voltage nonlinear resistor according to claim 1, wherein an average particle size of the mixture is 0.4 μm or less.   The current-voltage nonlinear resistor according to any one of claims 1 to 5, wherein a standard deviation based on a particle size distribution of the mixture is 75% or less of an average particle diameter of the mixture.

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