JPS62208602A - Manufacture of voltage nonlinear resistance device - 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 Field of Industrial Application The present invention relates to a voltage non-linear resistor element which is composed mainly of zinc oxide and has a high resistance layer formed on the side surface of a sintered body which itself has voltage non-linearity. This relates to a manufacturing method.

BACKGROUND OF THE INVENTION Conventional voltage nonlinear resistor elements are generally called varistors and are used as voltage stabilizing and surge absorbing elements.

Among these, zinc oxide varistors, which are mainly composed of zinc oxide and to which small amounts of bismuth, cobalt, manganese, antimony, chromium, etc. are added, have recently become popular as gapless arresters due to their large surge current withstand capacity and excellent voltage nonlinearity. It is widely used as a replacement for silicon carbide varistors.

When using a zinc oxide varistor as an arrester, there are two extremely important characteristic factors. The first is discharge endurance characteristics. This is 4× specified in JRC-187-1973.
This is the peak current limit value obtained by applying a 10 μs impact current twice at 6 minute intervals. The second is the energization life characteristic, which is the time it takes for the arrester element to reach thermal runaway when a specified alternating current voltage is applied. Normally, the ambient temperature is 100'C.
With the above conditions, the charging rate (V applied voltage x 100/V+mA) is set to 90% or more, and an accelerated test is performed to predict the lifespan. In recent years, there has been a strong demand for the development of high-performance arrester elements that have both of these characteristics.

As conventional methods for manufacturing stain positive nonlinear resistor elements (arrestor elements), Japanese Patent Laid-Open No. 66-69804 and Japanese Patent Publication No. 66-698
Publication No. 0-15126 is known. The former is zinc oxide with a small amount of bismuth oxide.

Cobalt oxide, manganese oxide, nickel oxide, etc. are added to the molded body obtained through pulverization, mixing, and granulation processes, or the side surface of a calcined body calcined at 700°C to 1150°C.
After coating a material containing n2SiO4, Zn7Sb2O12, Bi2O5, etc., it is sintered to produce an arrester element having a high resistance layer on the side surface. The latter involves placing antimony oxide, bismuth oxide, and silicon oxide in a firing container when firing a molded body obtained in the same manner, and producing an arrester element having a high-resistance layer on the side surface through a gas-solid reaction. It is something to do.

Problems to be Solved by the Invention The former method has disadvantages in that the structure of the side high resistance layer is unstable, the adhesion between the element and the side surface agent is poor, and the discharge withstand capacity is low. In addition, in the latter method, the vapor of a coating agent made of 56-diSb2O5, Bi2O5, etc. placed appropriately inside the firing container reacts with the molded body, so the thickness of the high-resistance layer on the side surface cannot be sufficiently thickened, and the discharge withstand capacity is reduced. Not only is this method low, but the number of elements that can be fired in the same firing container is limited, and mass productivity is lacking.

The present invention solves these problems and aims to improve the performance of a zinc oxide varistor as an arrester, that is, to significantly improve the discharge withstand characteristics 1 and the charging life characteristics.

Means to Solve the Problems In the present invention, in order to solve the above problems, two high-resistance layers with different components are formed on the sides of a molded body or calcined body whose main component is zinc oxide. By doing so, it increases the adhesion between the high resistance layer and the element and prevents Bi2O5 from scattering from the element.
It is characterized by forming a high resistance layer with a stable structure.

According to the method for manufacturing a voltage nonlinear resistor element according to the present invention, a solid agent made of SiO2 or Sb2O5 is applied to the side surface of a molded body or a calcined body of a zinc oxide varistor element, and the upper part thereof is A second layer containing SiO2 as the main component
After coating the side surface agent, it is fired to form a high resistance layer on the side surface of the varistor element.
A stable two-layer structure of Zn2SiO4 can be obtained in the two-layer part. This not only increases the adhesion between the varistor element and the high-resistance layer, improving the discharge withstand capacity, but also suppresses Bi2O3 scattering from inside the varistor element by covering the Zn2SiO4 layer on top of the high-resistance layer. Electrical life characteristics can also be greatly improved.

EXAMPLES Hereinafter, the manufacturing method of the present invention and the voltage nonlinear resistor element obtained thereby will be explained in detail based on examples.・ First, add Bi2O30,6 to the ZnO powder based on the total amount.
Mol%, GO2030, 5mol%, Mn020.5
mole%.

Sb2O31.0 mo/l/%, Cr2O30+E5
Mo/l/% and N100.25 mol% were added, thoroughly crushed and mixed, and then granulated to obtain a raw material powder. This raw material powder was compression molded to a size of 40 mm in diameter and 30 mm in thickness. The molded body thus obtained was fired at 900°C for 2 hours and cooled to obtain a calcined body.

On the other hand, the paste for the side high resistance layer is Sb2O3゜Bi
Raw material powder mixed with 2O3 and SiO2 in appropriate proportions, ethyl cellulose 25wt%, phthyl calhitol 76w
t% of the binder was blended in a weight ratio of 1:30 and kneaded uniformly. In the present invention, the paste for the side high resistance layer is made of SiO2, Sb
There are two types: one for the lower layer made of 2Os and one for the upper layer mainly composed of SiO2.

A paste for the lower layer was applied to the side surface of the calcined body and dried, then a paste for the upper layer was applied, and after drying again, it was sintered at 1200°C in air. Both end faces of the sintered body thus obtained were polished to form sprayed aluminum electrodes.

FIG. 1 is a cross-sectional view of the voltage nonlinear resistor element obtained as described above, in which 1 is a sintered body mainly composed of ZnOf, 2
The first side high resistance layer is mainly composed of Zn7Sb2O12.
The layer (lower layer), 3 is a side high resistance layer second layer (upper layer) mainly composed of zn2sio4, and 4 is an electrode formed by aluminum spraying. The components of the side high resistance layers 2 and 3 were confirmed by X-ray diffraction. Furthermore, analysis using an X-ray microanalyzer revealed that the first layer (lower layer) 2 contains M.
n, Go, Gr, etc. are dissolved in solid solution, and the second layer (upper layer)
It was confirmed that Go was mainly dissolved in solid solution in No. 3.

Table 1 below is a composition table of side additives for the first and second layers of the side high resistance layer. The side material for the first layer is SiO2,
It consists of Sb2O3, and the side surface agent for the second layer is SiO2,
Consists of Bi2O5.

(Left below) 9.

Vane <Table 1> Unit: mol% This side surface agent is applied to the calcined body in the order of the side surface agent for the first layer and the side surface agent for the second layer, and after sintering, an Aβ metallicon electrode is attached and the v1mA/ mm, V+mA/V1o72x+
I checked the appearance etc. The results are shown in Table 2 below.

For comparison, conventional example 1 and LteBi2O5+ Zn7Sb2
10 mol% and 10 mol% of O12+SiO2, respectively.
When a surfacing agent containing 80 mol% of a surfacing agent is applied to a calcined body, as in Conventional Example 2, coating agents containing 10 mol% and 90 mol% of Bi2O5 and Sb2O5, respectively, are placed in the firing container and a gas-solid phase reaction is performed. Added data when a high resistance layer is formed on the side surface.

(Left below) 15.

As can be seen from Table 2, v1mA/mm shows a decreasing tendency as the Bi2O5 concentration in the second layer side surface material increases, whereas V'+mA/V+o□A tends to increase. However, the Bi2O5 concentration in the second layer side surface agent was 4
If it exceeds 0 mol%, a flow of lateral agent will occur, and V + mA
/V+ o tIA, on the contrary, increases slightly. In addition, as the Sb2O3 concentration in the first layer sidewall agent increases, V1
mA/v1o□A is in the opposite direction.

FIGS. 2 to 9 show the results of the discharge withstand characteristics 1 and the energized life characteristics of voltage nonlinear resistor elements produced by the manufacturing method of the present invention.

Here, in the discharge endurance test, an impact current of 4×10 μs specified in Jll-187-1973 was applied twice in the same direction at 5-minute intervals, and appearance abnormalities were checked. The test is 1
It was performed in a step-up manner for every 0KA, and is indicated by a solid line with black circles in the figure. However, for samples that did not withstand two shock currents, the SKA was subtracted from the applied current. Furthermore, the charging life test was conducted at an ambient temperature of 130°C and a charging rate of 96°C.
% (60f(zAG)), and the leakage current is 10
Thermal runaway was determined to have occurred when mA was reached, and the time required for this is indicated by a dotted line marked with a white circle in the figure.

Table 3 below shows the discharge withstand characteristics and energized life characteristics of Conventional Examples 1 and 2.

(Left below) 17.

Bi/ As seen from Table 3, Bi2O3, Zn7Sb20
12.

The SiO2-based side surface agent application method (Conventional Example 1) has a discharge resistance of 50 KA, a single charge life of 29 hours, and Bi2O3.

The Sb2O6 gas-solid phase reaction system (Conventional Example 2) had a discharge capacity of 50 KA and a life of 31 hours when charged 9 times twice. Comparing FIGS. 2 to 9 with these, the discharge withstand capacity is found in the region where the degree of Sb2031M in the first layer side surface material is lower than 0.1 mol% and in the region where it is higher than 30 mol%.

It can be seen that the charged life characteristics are both at a low level, but are very excellent in the range of 0.1 to 30 mol %.

On the other hand, from FIGS. 4 to 6, Bi20d in the second layer side surface agent
! As the temperature increases, the energized life characteristics improve, 20~3
It reaches a peak at 0 mol%, and decreases again at 40 mol% or more. This is because the high-resistance layer on the side is exposed to Zn during the sintering reaction process.
This is thought to be because a part of the portion forming the 2SiO4 phase flows down due to excessive B12C)5, and conversely Bi2O3 from the varistor element becomes more likely to scatter. It can be seen that the power and discharge capacity characteristics are constant when the Bi2O5 concentration is 20 to 30 mol%, and then rapidly decrease. This is 19 when Bi2O5 increases.

It is thought that since Bi2O5 remains in the grain boundaries of Zn2SiO4 formed in the upper layer of the side high resistance layer, its strength decreases and the discharge withstand characteristics deteriorate. A 6 (Sb2O3: 10 mol%, S-02: 9゜mol/l/%) was used as the side surface agent for the first layer, and B2 (Bi2O3:
10 mol % and SiO2 190 mol %), the discharge capacity was 96 KA1 and the charging life was 320 hours, which shows that the performance is significantly improved compared to the conventional example.

As described above, the reason why the voltage nonlinear resistor element manufactured by the manufacturing method of the present invention exhibits high performance in both the discharge withstand characteristic and the charged life characteristic is presumed as follows. Conventional Bi2O
3. Zn7Sb2012 (Sb2O5).

When a SiO2 three-component single-layer side surface agent is used, the product is a mixed system of Zn7Sb2O12 and Zn2SiO4, whereas when a two-layer coating type side surface agent is used, the product is
A Zn7Sb2012 phase is generated in the second layer (upper layer), and a Zn2SiO4 phase is generated in the second layer (upper layer), resulting in an extremely cheap structure that contributes to improving discharge durability, and the Zn25iOa phase in the upper layer reduces Bi2O5 drift from the varistor element. It is thought that this contributes to improving the charging life characteristics.

In this example, only the case where two types of side surface agents for the side high resistance layer were applied to the calcined body was described, but there was also a case where both the side surface agents for the first layer and the second layer were applied to the molded body. It was confirmed that a similar effect was obtained when the side surface agent for the first layer was applied to the molded body and the side surface agent for the second layer was applied to the calcined body.

Effects of the Invention As described above, according to the present invention, a side surface agent made of Sb2O6°SiO2 is coated on the side surface of a molded or calcined body of a zinc oxide type varistor element, and a side surface agent made of Sb2O6°SiO2 is applied as an upper layer.
By applying and sintering a side surface agent consisting of the following, it is possible to manufacture a voltage non-linear resistor element with extremely high performance in discharge withstand characteristics 2 and energized life characteristics.

[Brief explanation of drawings]

21,-. FIG. 3 is a diagram showing discharge withstand characteristics and energized life characteristics of a voltage nonlinear resistor element produced by the manufacturing method of the invention. 1... Zinc oxide type varistor element, 2...
- Side high resistance layer 1st layer (lower layer), 3... Side high resistance layer 2nd layer (upper layer), 4... Electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person f-
---Rikoafuusu Oki\Risk Sochi 2---Rishunrei Tsuru Junkushirei-kashi 1 Sae (bottom 1) Figure 1 Figure 2 Figure 3-Lezcb Concentration 7 degrees (Morume 9 Figure 4 - 2θ4 reception (Mole 2) Figure 5 Yu β stone?03 Production (Mole Figure 6 → Btz0j leak (Mole 〆) Figure 7 - Biz O, 3J Reto (Mole 〆) Figure 8-BizoJl (-EIVI,) Figure 9

Claims (3)

[Claims] (1) A molded body containing zinc oxide as the main component and additives added so that the sintered body itself exhibits voltage nonlinearity has a temperature of 700 to 1150
Calcined in the temperature range of ℃, SiO
Main component is _2 and 0.1 to 30 mol% of Sb_2O_3
A first side surface agent containing S
Main component is iO_2 and Bi_2O_5 is 0 to 30 mol%
1. A method for manufacturing a voltage nonlinear resistor element, comprising applying a second side surface agent containing the second side surface agent, and then sintering to form a high resistance layer on the side surface of the sintered body. (2) SiO_2 on the side surface of a molded body whose main component is zinc oxide, with additives added so that the sintered body itself exhibits voltage nonlinearity.
A first side surface agent containing 0.1 to 30 mol% of Sb_2O_3 as a main component is applied, and SiO
A voltage nonlinear resistor element characterized in that a second side surface agent containing _2 as a main component and 0 to 30 mol% of Bi_2O_3 is applied and then sintered to form a high resistance layer on the side surface of the sintered body. Production method. (3) SiO_2 on the side surface of a molded body containing zinc oxide as the main component and additives added so that the sintered body itself exhibits voltage nonlinearity.
A first side agent containing Sb_2O_3 as a main component and 0.1 to 30 mol% is applied, and after calcining in a temperature range of 700 to 1150°C, a side surface agent containing SiO_2 as a main component and Bi as a main component is applied.
A method for producing a voltage nonlinear resistor element, comprising applying a second side surface agent containing 0 to 30 mol% of _2O_5 and then sintering to form a high resistance layer on the side surface of the sintered body.