JPS62237709A - Manufacture of voltage nonlinear resistance element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 specifically, to a voltage non-linear resistor suitable for a lightning arrester element with little variation in electrical characteristics. This relates to a manufacturing method.

(Prior Art) Conventionally, when manufacturing a voltage nonlinear resistor, for example, Bi
zOl, CozO=, Mn0z+ 5tlzO++
Various additives such as CrzOz+ 5iOz+Nip, Az, O, + bismuth borosilicate glass are added to the zinc oxide powder as is or after calcined, and then dispersed and mixed using a ball mill, vibration mill, disper mill, etc. Raw material powder was obtained.

(Problems to be solved by the invention) In the conventional mixing method described above, the average particle size is 0.5μ.
Various additives with an average particle size of several to several tens of micrometers are added to zinc oxide powder supplied as a fine powder of about 1000 yen, or additives are calcined and then ground to several tens of microns. Materials were added, dispersed, and mixed to obtain raw material powder. Therefore,
Unable to uniformly mix each component in the raw material powder,
This causes defects such as pinholes and voids in the voltage nonlinear resistor made from this raw material powder, and as a result, the resulting voltage nonlinearity, energized life, lightning surge resistance, etc. This had the disadvantage that the electrical characteristics of the product deteriorated and variations increased.

The purpose of the present invention is to eliminate the above-mentioned problems and provide a method for manufacturing a voltage nonlinear resistor that can reduce the number of defects, have good characteristics such as discharge endurance, and obtain a constant quality. be.

(Means for Solving the Problems) The method for manufacturing a voltage nonlinear resistor of the present invention includes adding and mixing finely pulverized various additives to a raw material powder containing zinc oxide as a main component, followed by granulation, molding, A method for manufacturing a voltage nonlinear resistor in which a sintered body is obtained by firing, characterized in that the difference in average particle size between the zinc oxide raw material powder and the finely pulverized additive in the mixing step is 2 μm or less. It is.

(Function) In the above-mentioned configuration, by mixing the zinc oxide powder and the additive powder with a difference in average particle size of 2 μm or less and a powder that approximates the average particle size of both, the zinc oxide powder and the additive powder can be mixed. It is possible to obtain raw material powder in which substances are uniformly mixed.

Therefore, it is possible to prevent the occurrence of pinholes, voids, etc. in the voltage nonlinear resistor made from the raw material powder according to the present invention, and to obtain a voltage nonlinear resistor that has good various characteristics and constant performance.

In addition, at this time, the particle size distribution of the additive is further adjusted to 3% of the average particle size.
It is preferable that the weight ratio of 10 times or more is 10% or less, since it is possible to obtain an additive powder with less variation in particle size.

Next, a method for manufacturing the voltage nonlinear resistor of the present invention will be explained.

First, for example, BizO30.1 to 2.0% in mol%,
C0ZO: lO, 1-2.0%, Mn0z 0.
1-2.0%.

5bzOz 0.1-2.0%, CrzO: + 0.
1~2.0%, Ni0O, 1~2.0%, Sing
A mixture of additives of 1.0 to 11.0% is preferably calcined at 700 to 850°C, and the calcined product is preferably dry crushed and then pulverized in a wet ball mill. Depending on the additive, calcination may not be performed, and in that case, the additive is directly pulverized in a wet ball mill. Fine pulverization is carried out until the difference in average particle size between zinc oxide and zinc oxide to be mixed in the next step is 2 μm or less, more preferably until both particles have approximately the same average particle size. In addition, the distribution of the pulverized particle size of the finely pulverized product is as follows:
A distribution in which the weight ratio of more than twice the amount is 10% or less is preferable. Note that since the average particle size of zinc oxide is about 0.3 to 0.7 μm, the average particle size of the additive is preferably 2.7 μm or less. Thereafter, the zinc oxide powder and the finely ground additive are uniformly mixed.

At this time, a predetermined amount of a polyvinyl alcohol aqueous solution is added as a binder. This mixing operation preferably uses a disper mill. After the obtained slurry is degassed under reduced pressure and granulated into fine particles, preferably using a spray dryer, the granulated product is pressure molded into a predetermined shape under a molding pressure of 800 to 1000 kg/c+a. The temperature increase/decrease rate is 50~7
The binder is scattered and removed by calcining under conditions of 0°C/hr and 800 to 1000°C for 1 to 5 hours. Next, an insulating coating layer is formed on the side surface of the calcined body. This insulating coating layer is Biz03.5b2o.

It is an oxide paste made by adding organic binders such as ethyl cellulose, butyl calpitol, n-butyl acetate, etc. to SjO□, and this is applied to the side surface of the calcined body to a thickness of 30 to 100 μm. Next, this temperature is raised and lowered at a rate of 40 to 60°C/h.
r, 1000-1300°C, preferably 1200°C, 3
Main firing is performed for ~7 hours.

In addition, 100 to 200 p of a glass paste prepared by adding ethyl cellulose, butyl calpitol, n-butyl acetate, etc. as an organic binder to glass powder is applied to the above-mentioned insulating coating layer.
Coated to a thickness of m and heated at a rate of 100 to 200 in air.
It is preferable to form the glass layer by heat treatment under the conditions of 0.5 to 2 hours at 400 to 600 degrees C./hr. Finally, both end faces of the voltage nonlinear resistor are polished smooth, and aluminum electrodes are provided by thermal spraying to obtain a voltage nonlinear resistor.

1" L-1 In the voltage nonlinear resistor with a diameter of 47 fins and a thickness of 20 fins created by the method described above, the difference in average particle size between the zinc oxide powder and the finely ground additive was set to 2 μm or less. Sample magnets 1 to 3 obtained using raw material powders within the range of the present invention and comparative magnets 1 obtained using raw material powders having a difference in average particle size outside the range of the present invention were prepared.

Note that all samples were calcined at 800° C. for 5 hours. Further, the fine pulverization was carried out so that the weight ratio of particles three times or more of the average particle diameter was 5% in the samples 11hl to 3 of the present invention and 8% in the comparative example. The obtained sample was subjected to ultrasonic flaw detection and measurement to determine the number of defects with a diameter of 0.5 mm or more to determine the defect occurrence rate. In addition, the discharge capacity is 100
0 A and 1200 A current with 2 ms current waveform 2
The number of times the device was destroyed after the application was repeated 0 times was determined as the discharge withstand destruction rate.

The results are shown in Table 1.

As is clear from Table 1, Sample No. 1, which is a voltage nonlinear resistor obtained using the raw material powder produced by the method of the present invention,
It was found that Samples No. 3 to 3 had a lower defect occurrence rate and a higher discharge withstand capacity than Comparative Examples.

Senketsu■-1 Diameter: 471cm, thickness: 20mm, similarly created using the method described above
In order to investigate the influence of the particle size distribution of the finely ground additive in the voltage nonlinear resistor of No. 111, the difference in average particle size between the zinc oxide powder and the finely ground additive was within the scope of the present invention of 2 μm or less. Samples 1 to 5 were prepared using raw material powders having various weight ratios of 3 times or more the average particle diameter.

For the obtained sample, the defect occurrence rate and the discharge withstand breakdown rate were determined in the same manner as in Example 1. The results are shown in Table 2.

As is clear from Table 2, among the raw material powders produced by the method of the present invention, the weight ratio of 3 times or more the average particle size is 10
It was found that Samples No. 1 and Kan 2, which were less than %, had a low defect occurrence rate and had good discharge durability.

(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 difference in average particle size between the zinc oxide powder and the finely pulverized additives can be reduced. When the thickness is 2 μm or less, a uniform raw material powder can be obtained, and as a result, a voltage nonlinear resistor with less defects and less variation and good discharge durability can be obtained.

Claims (1)

[Claims] 1. Production of a voltage nonlinear resistor in which a sintered body is obtained by adding and mixing finely pulverized various additives to a raw material powder containing zinc oxide as a main component, followed by granulation, molding, and firing. A method for producing a voltage nonlinear resistor, characterized in that the difference in average particle size between the raw zinc oxide powder and the finely ground additive in the mixing step is 2 μm or less. 2. The method for manufacturing a voltage nonlinear resistor according to claim 1, wherein the particle size of the additive has a particle size distribution such that 10% or less in terms of weight ratio is 3 times or more the average particle size.