JPH0476482B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing a voltage non-linear resistor, and more particularly, to a method for manufacturing a voltage non-linear resistor suitable for a lightning arrester element with little variation in electrical characteristics. (Prior art) Conventionally, in the production of voltage nonlinear resistors, which are usually insulators and have the characteristic of acting as conductors when excessive current flows, they are widely used in voltage stabilizing elements, surge absorbers, arresters, etc. , large amounts of water are used in the wet grinding process of raw materials. As this water, tap water has generally been used due to conventional costs and other considerations. (Problems to be Solved by the Invention) As described above, when a voltage nonlinear resistor is created using tap water, various electrical characteristics such as voltage nonlinearity, energized life, and lightning surge withstand capacity vary depending on the voltage. There was a drawback that it varied between non-linear resistors. This means that tap water contains Ca ²⁺ , Mg ²⁺ , K ^- , Na ⁺
Along with cations such as Cl ^- , CO ₃ ^2- , SO ₄ ^2- ,
It also contains many anions such as SO ₃ ^2- . Recently, among these various ions, an increase in the total amount of cations such as Ca ²⁺ reduces voltage nonlinearity, and an increase in the total amount of anions such as Cl ^- increases the viscosity of the mixture slurry and causes voids. It has been determined that these causes are related to the fluctuations in the electrical characteristics described above. The purpose of the present invention is to solve the above-mentioned problems based on these findings, and to manufacture a voltage nonlinear resistor that has good electrical characteristics such as voltage nonlinearity, energized life, and lightning surge resistance, and has little fluctuation. It seeks to provide law. (Means for Solving the Problems) The method for manufacturing a voltage nonlinear resistor of the present invention includes adding various additives made of metal oxides that cause voltage nonlinearity to a raw material whose main component is zinc oxide. In a method for producing a voltage nonlinear low antibody, in which the mixture is added and mixed, the mixture is granulated and then fired, and a high resistance layer consisting of an insulating layer is formed on the side surface of the obtained sintered body, at least during wet pulverization or wet mixing. The present invention is characterized in that the water used in any of the steps is water in which the total amount of Ca ²⁺ , Mg ²⁺ , K ⁺ , and Na ⁺ ions is less than 10 ppm. (Function) As mentioned above, cations in the water used in the manufacturing process have a negative effect on voltage nonlinearity, and anions cause voids that have a negative effect on the charging life and lightning surge resistance characteristics. By specifying the upper limit of the total content of cations and anions as 10 ppm each, it is possible to improve the charging life and lightning surge resistance characteristics without reducing voltage nonlinearity, and to improve these characteristics. fluctuations can be reduced. Note that it is preferable that the total amount of cations and anions be less than 2 ppm each, since electrical properties can be further improved. Next, the manufacturing method of the present invention will be described in detail. To obtain a voltage nonlinear resistor whose main component is zinc oxide, Bi ₂ O ₃ , Co ₂ O ₃ , MnO ₂ pulverized to a specified particle size, and zinc oxide raw material adjusted to a specified particle size are added to the zinc oxide raw material adjusted to a specified particle size.
Sb ₂ O ₃ , Cr ₂ O ₃ , SiO ₂ , NiO, Al ₂ O ₃ , B ₂ O ₃ ,
A predetermined amount of an additive such as Ag ₂ O was pulverized and mixed for 50 hours by wet pulverization using a ball mill and water specified in the present invention. After that, the pulverized product is dried, calcined, and then pulverized to a predetermined particle size. To this raw material powder, water and polyvinyl alcohol specified in the present invention are added in a predetermined amount, and the powder is granulated using a spray dryer. The molded body is molded into a specified shape under a molding pressure of 800 kg/ ^cm2 , and the molded body is heated at a heating/cooling rate of 60 kg/cm2.
The binder is scattered and removed by pre-calcining under the conditions of holding at 900°C for 2 hours at ℃/hr. Next, an insulating coating layer is formed on the side surface of the calcined body. In the present invention, an oxide paste prepared by adding ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as an organic binder to predetermined amounts of Bi ₂ O ₃ , Sb ₂ O ₃ , and SiO ₂ is calcined to a thickness of 30 to 100 μm. Apply to the sides of the body. Next, this was heated at a temperature increase/decrease rate of 50℃/hr.
Main firing is performed at 1200°C for 5 hours to obtain a voltage nonlinear resistor. Furthermore, a glass paste prepared by adding ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as an organic binder to glass powder is applied onto the insulating coating layer.
It is preferable to form a glass phase by applying the coating to a thickness of 100 to 200 μm and heat-treating it in air at a temperature increase/decrease rate of 150° C./hr and a holding time of 500° C. for 1 hour. Finally, both end faces of the voltage nonlinear resistor are polished smooth, and aluminum electrodes are provided by thermal spraying. (Example) A voltage nonlinear resistor having a diameter of 47 mm and a thickness of 20 mm was produced according to the method for manufacturing a voltage nonlinear resistor described above. At this time, the water used during wet grinding and mixing includes water whose total amount of cations and anions has been adjusted in advance to within the range of the present invention using an ion exchange resin machine, and water whose total amount of ions is outside the range of the present invention. Voltage nonlinear resistors of samples Nos. 1 to 5 were obtained using the following. Then, for each of the voltage nonlinear resistors obtained, the voltage nonlinearity index, ΔV _1nA after lightning surge,
Leakage currents were measured and their average values and standard deviations were determined. In addition, the thickness of the insulating coating layer of all these samples was about 30-100 micrometers, and the glass layer of about 50-100 micrometers thick was provided on the insulating coating layer. The results are shown in Table 1. In Table 1, the voltage nonlinearity index α is I=KV〓(I: current, V: voltage, K:
It was determined from the values of V _1nA and V ₁₀₀ 〓 _A based on the proportionality constant). Further, ΔV _1nA after a lightning surge indicates the rate of decrease in V _1nA after applying a current of 40 KA 10 times with a current waveform of 4×10 μs. Further, the leakage current ratio was determined from the current ratio I100 hours/Io hours after ₁₀₀ hours of power application compared to immediately after power application by applying power at an ambient temperature of 130° C. and a power application rate of 95%.

【table】

[Table] As is clear from Table 1, Samples Nos. 1 to 5, in which water with a total amount of ions within the range of the present invention was used during the manufacture of voltage nonlinear resistors, were more effective than Comparative Examples Nos. 6 to 8. A high voltage nonlinearity index, low ΔV _1nA after lightning surge, and low leakage current can be achieved, resulting in good characteristics such as voltage nonlinearity, energized life, and lightning surge withstand capacity, as well as their standard deviation values. It was confirmed that the characteristics were small and the fluctuations in characteristics were small. (Effects of the Invention) As is clear from the detailed explanation above, according to the method for manufacturing a voltage nonlinear resistor of the present invention, the upper limit of the total amount of cations and anions in the water used is set at 10 ppm each. By doing so, it is possible to obtain a voltage nonlinear resistor that has good electrical properties such as voltage nonlinearity, energized lifespan, and lightning surge resistance, and has little variation in these properties.

Claims (1)

[Scope of Claims] 1. Various additives made of metal oxides that cause voltage nonlinearity are added and mixed to a raw material whose main component is zinc oxide, and the mixture is granulated and then fired,
In a method for manufacturing a voltage nonlinear low antibody, which forms a high resistance layer made of an insulating layer on the side surface of the obtained sintered body,
At least as water used in either the wet grinding or wet mixing process, Ca ²⁺ , Mg ²⁺ ,
A method for producing a voltage nonlinear resistor, comprising using water in which the total amount of K ⁺ and Na ⁺ ions is less than 10 ppm. 2 The total amount of Ca ²⁺ , Mg ²⁺ , K ⁺ , Na ⁺ is 2 ppm
2. The method for manufacturing a voltage nonlinear resistor according to claim 1, wherein the total amount of Cl ^- , CO ₃ ^2- , SO ₄ ^2- , and SO ₃ ^2- is also less than 2 ppm.