JPH0812808B2 - Method of manufacturing voltage non-linear resistor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a voltage nonlinear resistor containing zinc oxide as a main component.

(Prior art) Bi ₂ O ₃ , Sb ₂ O ₃ , SiO ₂ , mainly containing zinc oxide,
It is widely known that resistors containing a small amount of additives such as CO ₂ O ₃ and MnO ₂ exhibit excellent voltage non-linearity, and the properties thereof are used for lightning arresters and the like.

In this voltage non-linear resistor, when a surge current such as lightning is applied to the element, discharge may occur mainly along the side surface of the element, so-called creeping discharge may occur, and the element may be destroyed, so Bi-Sb- It is common to provide a high resistance layer made of a Si-based compound or a Bi-Sb-Si-Zn-based compound.

(Problems to be Solved by the Invention) Of these, the Si component produces zinc silicate in the high-resistance layer and is effective in improving the lightning surge withstand capability. However, conventionally, crystalline SiO ₂ or the like was used as it was without crushing as a Si component addition, so that the particle size is coarse, and the zinc silicate phase, which is effective, is not uniformly generated until it is continuously and uniformly generated. There were cases. In such a case, the lightning surge withstand capability will not be improved and its variation will be large, and the side surface high resistance layer will also absorb moisture, and it will not be possible to obtain a voltage nonlinear resistor with good characteristics such as lack of long-term reliability. was there.

An object of the present invention is to solve the above-mentioned problems, and to provide a method of manufacturing a voltage non-linear resistor capable of improving the lightning surge withstand capability, having less variation, and improving the hygroscopicity of the lateral high-resistance layer. It is a thing.

(Means for Solving the Problems) A method of manufacturing a voltage non-linear resistor according to the present invention comprises a side surface of a voltage non-linear resistor containing zinc oxide as a main component and a side surface including at least a silicon compound, an antimony compound, and a bismuth compound. In the method for producing a voltage non-linear resistor in which a mixture for a high resistance layer is applied and then fired, the silicon compound in the mixture is amorphous silica and its average particle size is 9.5 μm.
It is characterized by being m or less.

(Operation) In the above-mentioned configuration, the present inventors have variously studied the method of applying the Si component, and as a result, using amorphous silica as the Si component in the mixture forming the high resistance layer,
When the average particle size is 9.5 μm or less, preferably 6 μm or less, a good zinc silicate phase is obtained, and as a result, the lightning surge withstand capability is improved and its variation is reduced as will be apparent from the examples described later. It was also found that the hygroscopicity of the side surface high resistance layer is also improved.

The method for producing the amorphous silica is not particularly limited, but if the one obtained from the metathesis reaction of sodium silicate or the one obtained by the thermal decomposition of silicon tetrachloride is used, the examples described below are used. As is clear from the above, the characteristics are improved, which is preferable. The purity of SiO ₂ is preferably 95% or more.

Further, as a mixture for forming the lateral high-resistance layer, amorphous silica, a bismuth compound, and an antimony compound are used as Si.
In terms of _{O 2, Bi 2 O 3,} Sb 2 O 3, SiO 2 70~95 mol%, preferably 80 to 90 mol%, Bi ₂ O ₃ 1 to 15 mol%, preferably 3 to 10 mol% , Sb ₂ O _{3 3 to} 20 mol%, preferably 5 to 15
It is preferable to add a zinc compound in an amount of 150 mol% or less, preferably 80 mol% or less in terms of ZnO by external distribution, if necessary, in terms of ZnO, and the average particle size of the whole is preferably 10 μm or less. The thickness of the side surface high resistance layer is 30 to 150 μm.
Is preferred.

Although a bismuth compound, an antimony compound, and a zinc compound are specified as the composition of the mixture for the lateral high-resistance layer, any compound can be converted into an oxide at 1000 ° C. or lower, preferably 800 ° C. or lower. Specific examples thereof include oxides, carbonates, nitrates and hydroxides, with oxides being most preferred.

(Example) In order to obtain a voltage nonlinear resistor containing zinc oxide as a main component, first, a zinc oxide raw material adjusted to a predetermined particle size and Bi ₂ O ₃ , CO ₃ O ₄ , MnO ₂ adjusted to a predetermined particle size were prepared. , Sb ₂ O ₃ , Cr ₂ O ₃ , Si
A predetermined amount of an additive such as O ₂ or NiO is mixed. On this occasion,
A predetermined amount of an aqueous polyvinyl alcohol solution or the like is added to these raw material powders, preferably mixed by a disper mill, and then preferably granulated by a spray dryer to obtain a granulated product. After granulation, it is molded into a predetermined shape under a molding pressure of 800 to 1000 kg / cm ² . The temperature rise / fall rate of the molded body is 50 ~
Preliminary calcination is performed at a temperature of 70 ° C / hr and a holding time of 800 to 1000 ° C for 1 to 5 hours.

Before calcination, the molded body should be heated / cooled at a rate of 10-100 ° C / hr.
It is preferable to keep the binder at 400 to 600 ° C. for 1 to 10 hours to scatter and remove the binder. The element body of the present invention means a degreased body obtained by heat-treating a molded body under the above conditions.

Next, a side surface high resistance layer is formed on the side surface of the calcined body that has been calcined. In the present invention, a mixture paste for a lateral high-resistance layer having a predetermined amount of a bismuth compound, an antimony compound, a silicon compound, etc., added with ethyl cellulose, butyl carbitol, n-butyl acetate or the like as an organic binder, is 60 to 300 μm
Apply to the side of the calcined body to the thickness of. At this time, in the present invention, as the silicon compound, amorphous silica having an average particle diameter of 9.5 μm or less is used. The mixture paste may be applied to the element body. Next, this is heated / cooled at a temperature of 40-60 ° C / hr,
The main calcination is performed at 1000 to 1300 ° C, preferably 1100 to 1250 ° C for 3 to 7 hours. In addition, a glass paste obtained by adding ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as an organic binder to glass powder is applied on the above-mentioned lateral high-resistance layer to a thickness of 100 to 300 μm, and the temperature rising / falling rate is 10 in air.
It is preferable to form the glass layer by heat treatment under the conditions of 0 to 200 ° C./hr and 400 to 600 ° C. holding time of 0.5 to 2 hours.

After that, both end surfaces of the obtained voltage nonlinear resistor are
Polishing is carried out with water, preferably oil, with an abrasive corresponding to # 400 to 2000 such as ₂ O ₃ or diamond. Next, after cleaning the polished surface, electrodes are provided on the polished both end surfaces by, for example, aluminum, for example, by thermal spraying to obtain a voltage nonlinear resistor.

Hereinafter, the results of actually measuring various characteristics of the voltage nonlinear resistor within and outside the range of the present invention will be described.

In a voltage nonlinear resistor having a diameter of 47 mm and a thickness of 20 mm prepared by the method described above, in order to investigate the influence of the state and average particle size of the silicon compound in the mixture for the lateral high resistance layer, the composition of the element body was Bi ₂ O ₃ 1.0 mol%, Co ₃ O ₄ 0.7 mol%, MnO ₂
0.5 mol%, Sb ₂ O ₃ 1.0 mol%, Cr ₂ O ₃ 0.5 mol%, NiO 0.5
Mol%, Al ₂ O ₃ 0.005 mol%, SiO ₂ 2 mol% and the balance
Sample Nos. 1 to 9 within the scope of the present invention in which amorphous silica is used as the silicon compound as ZnO and the average particle size is 9.5 μm or less, and Comparative Example No. which does not satisfy the scope of the present invention in any point .1 to 4 were prepared, and the lightning surge withstand destruction rate and the hygroscopicity of the side surface high resistance layer were measured. Here, in the mixture other than the silicon compound for the side surface high resistance layer, bismuth oxide having an average particle size of 5 μm was used as the bismuth compound, and antimony oxide having an average particle size of 3 μm was used as the antimony compound. Mixtures for side high-resistance layer is SiO ₂ 85 mol%, Bi ₂ O ₃ 5 mole%, and the ternary Sb ₂ O ₃ 10 mol%. Regarding the amorphous silica among the silicon compounds used, those produced according to the manufacturing method of FIGS. 1 (a) to (c) are used, and those according to FIG. 1 (a) are A and FIG. (B)
In Table 1, those according to the above are shown as B, and those according to FIG. 1 (c) are shown as C. The results are shown in Table 1.

In Table 1, lightning surge withstand destruction rate is 100KA, 110K
The proportion of the pulse currents of A and 120 KA that were destroyed after being applied twice with a current waveform of 4/10 μs is shown. Regarding the hygroscopicity of the side surface high resistance layer, the element was immersed in the fluorescent flaw detection liquid at a pressure of 200 kg / cm ² for 24 hours, and then the hygroscopic state was inspected. The sample with a small number was marked with Δ, and the sample with a large amount of blurring was marked with x.

From the results shown in Table 1, the present invention samples Nos. 1 to 9 in which amorphous silica was used as the silicon compound and whose average particle diameter was 9.5 μm or less were comparative examples which did not satisfy the present invention in any respect. It was found that, as compared with Nos. 1 to 4, excellent lightning surge resistance and good hygroscopicity were exhibited. Further, among the present invention, when the one obtained by utilizing the metathesis reaction of sodium silicate as the amorphous silica or the one obtained by utilizing the thermal decomposition reaction of silicon tetrachloride is used, the lightning surge withstand capability is further reduced. It turns out that it is preferable. Further, it is found that the average particle size of the silicon compound is preferably 6 μm or less because the lightning surge withstand breakdown rate is further reduced.

(Effects of the Invention) As is clear from the above description, according to the method for producing a voltage non-linear resistor of the present invention, the state and average particle size of the silicon compound in the mixture for the lateral high-resistance layer should be defined. As a result, it is possible to obtain a voltage non-linear resistor having good lightning surge withstand capability and less variation, and having improved moisture absorption of the side surface high resistance layer.

In addition, good characteristics were confirmed with respect to switching surge withstand capability, voltage application life, and limiting voltage.

[Brief description of drawings]

1 (a) to 1 (c) are flow charts showing an example of a method for producing amorphous silica used in the present invention.

Claims (1)

[Claims] 1. A voltage non-linear resistor in which a mixture of at least a silicon compound, an antimony compound and a bismuth compound for a side surface high resistance layer is applied to the side surface of a voltage non-linear resistor containing zinc oxide as a main component and then fired. 5. The method for producing a voltage non-linear resistor according to item 2, wherein the silicon compound in the mixture is amorphous silica and the average particle size is 9.5 μm or less.