JPH02229402A - Manufacture of voltage dependent nonlinear resistor - Google Patents

Abstract

PURPOSE:To enhance an electrical characteristic such as a lightning surge strength or the like and a hygroscopic property of a side-face high-resistance layer by a method wherein a side face of a voltage dependent nonlinear resistor raw body which is composed mainly of zinc oxide and which contains a bismuth component, an antimony component and a silicon component is coated with a mixture of compositions which contain amorphous silica, an antimony compound, a bismuth compound and a zinc compound at a specific amounts and a high-resistance layer is formed. CONSTITUTION:A composition of a side-face high-resistance layer is a quaternary system of SiO2-Sb2O3-Bi2O3-ZnO. That is, a side face of a voltage dependent nonlinear resistor raw body which is composed mainly of zinc oxide and which contains a bismuth component, an antimony component and silicon component is coated with a mixture, for insulating coating use, of amorphous silica, an antimony compound, a bismuth compound and a zinc compound; a high-resistance layer containing zinc silicate and spinel is formed on a side face of a sintered substance. A composition of this mixture is as follows: the amorphous silica as expressed in terms of SiO2 is 65 to 91mol%; the antimony compound as expressed in terms of Sb2O3 is 2 to 15mol%; the bismuth compound as expressed in terms of Bi2O3 is 7 to 20mol%; the zinc compound as expressed in terms of ZnO is ZnO/(SiO2+Sb2O3+Bi2O3)=0.1 to 1.0.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a voltage nonlinear resistor containing zinc oxide as a main component.

? Conventional technology) Conventionally, zinc oxide is the main component and the former tch. Sbt03
, sso. It is widely known that resistors containing small amounts of additives, such as , COJ4+ MnO■, exhibit excellent voltage nonlinearity, and are used in lightning arresters and the like by taking advantage of this property. In this voltage nonlinear resistor, when a lightning surge current is applied to the element, discharge mainly occurs along the side of the element, so-called creeping discharge, which may destroy the element. compound or 81-Sb-Si-
It is common to provide a side high resistance layer made of a Zn-based compound.

(Problem to be Solved by the Invention) In these voltage nonlinear resistors, there have been attempts to increase the varistor voltage (V+-a) of the resistor to miniaturize devices such as arresters. It is generally known that lowering the varistor voltage increases the varistor voltage. However, when the firing temperature is lowered, the adhesion between the side high-resistance layer and the resistor body decreases, resulting in a decrease in lightning surge resistance. Ta.

In order to improve this point, the present applicant has published Japanese Patent Application Laid-Open No. 631366
In Publication No. 03, Z of a predetermined composition is used as a side high resistance layer.
nO-SiOz-BtzO. -Sb. By using a 02-based mixture and increasing the Si01 content in the element body to 7 to 11 mol%, we have created a voltage nonlinear resistor that has good characteristics with a varistor voltage of 400 V/1 m or higher even when the firing temperature is lowered. Disclose what you can get.

However, in the technique described in JP-A-63-136603 mentioned above, it is necessary to increase the amount of Sift added in the element, which makes it difficult to uniformly disperse the zinc silicate phase in the element, and the switching surge resistance etc. There was a problem with the decline. In addition, the crystal award S
Since iO■ and the like were used as they were without being crushed, the particle size was coarse, and the zinc silicate phase, which is effective only if it is formed uniformly, was sometimes formed unevenly. In such a case, the lightning surge resistance does not improve and its variation becomes large, and the high resistance layer on the side also absorbs moisture, resulting in a lack of long-term reliability. There was a problem in that it was not possible to obtain a voltage nonlinear resistor with good characteristics.

The purpose of the present invention is to solve the above-mentioned problems and provide a voltage nonlinear resistor that can obtain electrical characteristics such as good lightning surge resistance even at high varistor voltages, and can also improve the hygroscopicity of the side high resistance layer. The present invention aims to provide a method for manufacturing.

(Means for Solving the Problems) The method for manufacturing a voltage nonlinear resistor of the present invention includes a method for manufacturing a voltage nonlinear resistor element that contains zinc oxide as a main component, a bismuth component, an antimony component, and a silicon component. , at least amorphous silica, an antimony compound, a bismuth compound, a zinc compound, and the amorphous silica is converted to SiO■ from 65 to
91 mol%, antimony compound sb, o, 2 to 15 mol%, bismuth compound Bi! 7 to 20 mol% in terms of Oi, Zn in terms of zinc compound to ZnO
O / (Sing + SbzOz+Biz(h
) = 0.1 to 1.0 is applied, and zinc silicate (ZnzSiO4) is applied to the side surface of the fired body.
) and spinel (Zn7SbzO+ z).

(Function) In the above structure, the composition of the side high resistance layer is a quaternary system of Si02-SbzO+-Bit03-ZnO in a predetermined amount, and amorphous silica is used as the Si02 source material in terms of Si01. 65 to 91 mol%, preferably 73 to 86 mol%, of the antimony compound Sb! 03, preferably 4 to 10 mol%, the bismuth compound is Bi. O. 7 to 20 mol%, preferably 10 to 17 mol%, in terms of ZnO, Zoo/(SiOz + SbzOi + Bi
By mixing so that the zOi) is 0.1 to 1.0, preferably 0.2 to 0.7, electrical characteristics such as good lightning surge resistance can be obtained even at high varistor voltage, and the side It has been found that the hygroscopicity of the high-resistance layer can also be improved.

Here, amorphous silica is used as Sin. Converting to 65-91
Mol%, antimony compound converted to Sb203: 2~
15 mol% of the bismuth compound was added to BigO. Converting to 7
~20 mol%, Zn0/ in terms of zinc compound as ZnO
(SiOt+Sb!Off+Bi,03) is 0.1~
The reason for numerically limiting the composition to 1.0 is that if any composition is outside this range, electrical characteristics such as lightning surge resistance will deteriorate, as will be clear from the examples described later.

Here, the amorphous silica reacts with the zinc compound by firing to produce zinc silicate. Antimony compounds also react with zinc compounds to produce spinel. These zinc silicate and spinel are thought to play an important role in improving the adhesion between the side high-resistance layer and the resistor body, and in improving the lightning surge resistance characteristics of the device. Note that the zinc compound needs to react with the amorphous silica or antimony compound during firing, and it is not preferable for the zinc compound to remain as a zinc compound after firing. Moreover, it is preferable that zinc silicate be produced continuously. In addition, the bismuth compound acts as a Franks to facilitate the above reaction, and also diffuses into the resistor body, playing an important role in improving characteristics such as opening/closing surge resistance.

In addition, the use of amorphous silica as the Si02 source material allows a uniform and good zinc silicate phase to be obtained in the side high resistance layer, which improves lightning surge resistance and reduces its dispersion. This is because the hygroscopicity of the layer is also improved.

There are no particular limitations on the manufacturing method of the amorphous silica used, but if one obtained from the metathesis reaction of sodium silicate or the one obtained from the thermal decomposition of silicon tetrachloride is used, various properties will be obtained. This is preferable because it improves. Moreover, its purity is Sin. It is preferable that it is 95% or more.

Furthermore, the average particle size of the amorphous silica, antimony compound, bismuth compound, and zinc compound used is 10 liters!
It is preferable that it is below m.

Here, an antimony compound, a bismuth compound, and a zinc compound are specified as the composition of the insulating coating mixture other than amorphous silica, but each compound is one that changes to an oxide at a temperature of 1000°C or less, preferably 800°C or less. That's fine. Specific examples include carbonates, nitrates, hydroxides, etc., but oxides are most preferred. Further, the composition of the voltage nonlinear resistor element is not limited, and any conventionally known composition can be used, but in particular, a silicon component of Sin. The content is preferably 0.1 to 7 mol%, more preferably 0.5 to 4 mol%. The silicon component precipitates in the grain boundary phase together with the bismuth component, and the varistor voltage (V+-
A) has the effect of improving. If it is less than 0.1 mol%, the grain growth suppressing effect will be insufficient and the varistor voltage will not improve, and the charging life and limiting voltage characteristics may deteriorate, and if it exceeds 7 mol%, the lightning surge resistance will deteriorate. This is because the varistor voltage may also decrease after the lightning surge is applied.

More preferably, it is amorphous so that the reaction proceeds smoothly.

(Example) To obtain a voltage nonlinear resistor whose main component is zinc oxide,
First, zinc oxide raw material adjusted to a predetermined particle size, bismuth oxide, cobalt oxide, manganese oxide, adjusted to a predetermined particle size,
A predetermined amount of additives such as antimony oxide, chromium oxide, silicon oxide, nickel oxide, silver oxide, boron oxide, etc. are mixed. Silver nitrate or boric acid may be used instead of silver oxide or boron oxide. Preferably, bismuth borosilicate glass containing silver is used. At this time, a predetermined amount of polyvinyl alcohol aqueous solution and a predetermined amount of aluminum nitrate solution as an aluminum oxide source are added to these raw material powders,
After mixing preferably using a disper mill, the mixture is preferably granulated using 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 zO.

The molded body was heated to 800°C at a heating and cooling rate of 50 to 70°C/hr.
Temporary firing is carried out under conditions of holding time at ~1000°C for 1 to 5 hours.

In addition, before calcination, the molded body is heated and cooled at a rate of 10 to 100"C.
It is preferable to hold at 400 to 600'C for 1 to 10 hours to remove the binder by scattering. Here, the element body of the present invention refers to a molded body, a degreased body obtained by heat-treating the molded body under the above-mentioned conditions, or a calcined body.

Next, a side high resistance layer is formed on the side surface of the element body.

In the present invention, the bismuth compound is calculated from 7 to 7 in terms of old go3.
20 mol%, antimony compound 2 to 15 mol% in terms of SbzOz, amorphous silica 6 in terms of SiO2
5 to 91 mol%, ZnO based on zinc compound converted to ZnO
/SiO. + Sb. O*+BizOs) =0.
60 to 300 l of a mixture paste for the side high resistance layer, which is prepared by adding ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as an organic binder to a predetermined amount of 1 to 1.0 l.
Apply to the side of the element to a thickness of /II1. At this time, in the present invention, amorphous silica having an average particle size of 10 μm or less is used.

Next, this temperature was raised and lowered at a rate of 40 to 60°C/hr, 10
00-1250°C preferably 1050-1190°C
, 3 to 7 hours. A glass paste prepared by adding organic binders such as ethyl cellulose, butyl carbitol, n-butyl acetate, etc. to glass powder was applied to the above-mentioned side high-resistance layer to a thickness of 100 to 300 μ■, and the temperature was raised and lowered in the air at a rate of 100~200″C/hr, 40
It is preferable to form the glass layer by heat treatment at 0 to iooo°C for 0.5 to 2 hours.

After that, both end faces of the obtained voltage nonlinear resistor were bonded to SiC,
A j! ! #400-200 of Oh diamond etc.
Equivalent to 0? Polishing with an abrasive agent using water, preferably oil. Next, after cleaning the polished surfaces, electrodes made of aluminum, for example, are provided on both polished end surfaces by thermal spraying, to obtain a voltage nonlinear resistor. Below, the results of actually measuring various characteristics of voltage nonlinear resistors within and outside the range of the present invention will be described.

In order to investigate the influence of the composition of the mixture for the side high resistance layer in a voltage nonlinear resistor with a diameter of 47 m and a thickness of 20 am created by the method described above, the composition of the element body was BlxOz.
1.0 mo/l/%, Co=Q40.7 mo7L/%
, MnO. 0.5 mol%, Sb103 1.0 mol%
,Cr,Q,, o. s Mo/L/%, NiO O. 5
Mol%, An! gos 0.005 mol%, amorphous SiO■1. Bismuth borosilicate glass with θ mol% and the balance being ZnO and further containing silver 0.01-0.5
% by weight, the composition of the side high resistance layer uses amorphous silica as silicon, and has the composition shown in Table 1, and the varistor voltage is varied by changing the firing temperature. Samples within the scope of the present invention. No. Comparative samples Nal to 22, which do not satisfy the scope of the present invention in any aspect of the composition of the side high resistance layer, were prepared, and the respective varistor voltages (
■、．． ^), lightning surge withstand capacity, switching surge withstand capacity, and moisture absorption of the side high-resistance layer were measured. The results are shown in Table 1.

In Table 1, the lightning surge withstand capacity is expressed as the energy withstand capacity, and the energy withstand capacity is a means of relatively evaluating the withstand capacity of resistors with different varistor voltages, and is calculated by energy {1 (current x voltage x application time). ). The opening/closing surge withstand capacity is indicated as × for those that break down after 20 repeated applications of currents of 400 A, 500 A, and 600 A with a current waveform of 2 ms, and as O for those that do not break. Regarding the hygroscopicity of the side high-resistance layer, the device was immersed in fluorescent deep wound liquid for 24 hours at a pressure of 200 kg/cm. , those with blurring were indicated as ×.

From the results in Table 1, inventive sample No. 1 whose composition of the high resistance layer was within the range of the present invention. Resistors Nos. 1 to 30 can obtain good electrical characteristics even with high varistor voltage, and have better lightning surge resistance, etc., than comparative samples Nα1 to 22, which do not satisfy the present invention in any respect. It was found to exhibit good electrical properties and good moisture resistance of the side high resistance layer.

(Effects of the Invention) As is clear from the above explanation, according to the method for manufacturing a voltage nonlinear resistor of the present invention, by limiting the composition in the high resistance layer, electrical properties such as good lightning surge resistance can be achieved. It is possible to obtain a voltage non-linear resistor which can obtain the same characteristics even at a high varistor voltage, and which can also improve the hygroscopicity in the side high resistance layer.

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Claims (1)

[Claims] 1. At least amorphous silica, an antimony compound, a bismuth compound, a zinc compound, and amorphous silica are applied to the side surface of the voltage nonlinear resistor element body, which is mainly composed of zinc oxide and contains a bismuth component, an antimony component, and a silicon component. SiO_
65 to 91 mol% in terms of 2, antimony compound S
2 to 15 mol% in terms of b_2O_3, 7 to 20 mol% in terms of bismuth compounds as Bi_2O_3, and ZnO/(SiO_2+Sb_) in terms of zinc compounds as ZnO.
2O_3+Bi_2O_3)=0.1-1.0 A voltage non-linear method characterized by applying a mixture for insulation coating with a composition of 0.1 to 1.0 and forming a high-resistance layer containing zinc silicate and spinel on the side surface of the fired body. Method of manufacturing a resistor.