JPS60206003A - Nonlinear resistor - 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] [Technical Field of the Invention] The present invention uses a sintered composite mainly composed of zinc oxide and having voltage non-linear resistance characteristics to form a high resistance layer on the side surface of a molded element body. The present invention relates to a voltage nonlinear resistor consisting of a voltage nonlinear resistor.

[Technical Background of the Invention] A voltage nonlinear resistor is generally called a varistor, and its excellent nonlinear voltage-current characteristics are utilized for lightning arresters and surge absorbers for the purpose of voltage stabilization or surge absorption. Widely used.

A typical example is the recently developed zinc oxide varistor. The main component is zinc oxide, to which a small amount of oxides such as bismuth, antimony, cobalt, manganese, chromium, etc. are added, mixed, granulated, molded, and then fired at high temperature in air to form a sintered body. It is constructed by attaching electrodes. Its non-linear resistance properties are very good, and the sintered body consists of grain boundary layers formed by zinc oxide particles and additives surrounding them. It is believed that this is due to the interface between

[Problems with Background Art] By the way, the use of these zinc oxide-based varistors as power surge arresters has the following drawbacks. In other words, a single zinc oxide element has poor moisture resistance and is not suitable for use in harsh environments such as lightning arresters, and the rate of change in resistance of the nonlinear resistor is large when a large current pulse is applied, so it cannot be used over a long period of time. It is unsuitable for overvoltage protection devices that are subjected to lightning pulses or voltage surge pulses over a long period of time. Therefore, there has been a demand for a metal oxide nonlinear resistor that has stable electrical characteristics over a long period of time.

In response to these demands, epoxy resin Co.
It has been proposed and implemented to form a high-resistance layer mainly composed of S b20"12, 2 n2S i 04. However, the epoxy resin coating has poor electrical resistance properties;
Furthermore, although the moisture resistance properties etc. of the Zny Sb20+z and Zn25 iO4 systems have been improved, the problem of a large rate of change in resistance when a large current pulse is applied still remains. It is an object of the present invention to provide a metal oxide nonlinear resistor whose electrical characteristics are less likely to deteriorate even when overcurrent pulses are repeatedly applied over a long period of time.

[Summary of the Invention] In order to achieve the above object, the present invention provides a sintered composite mainly composed of zinc oxide, in which bismuth oxide, iron oxide, and antimony are added to the side surface of a molded thread body, such as B12O3, Fe20s,
In terms of 5b203, Soreso 0.3 to 20 mol%,
50-95 mol%, 5-50 mol% with a total of 1
By forming a high resistance layer made of a composition containing 00 mol%, a voltage nonlinear resistor with a small rate of change in varistor voltage when a large current pulse is applied is obtained. It is.

[Embodiments of the invention] Examples of the present invention will be described in detail below.

FIG. 1 is a cross-sectional view of a non-linear resistor according to the present invention. In the figure, 1 is a sintered element whose main component is zinc oxide, 2 is a high-resistance layer formed on both sides, and 3 is an upper and lower part. Electrodes provided on both sides.

To manufacture a non-linear resistor having such a configuration, for example, the following procedure is performed.

First, bismuth oxide (Bi) was added to zinc oxide (ZnO) powder.
zO3), cobalt oxide (C0203).

Manganese oxide (MnO), antimony oxide (SbzO)
3), nickel oxide (Nip) powder of 0.5 to 5
These raw material powders were added in a mole % range, and mixed together with water, a dispersant, a binder, and a lubricant in a mixing device in order to thoroughly mix these raw material powders.

This mixture slurry was granulated using a spray dryer so as to have an average particle size of, for example, 100 microns, and the powder was pressed into a disk having a diameter of 4Q mm and a width of 40 mm. After firing in air at 500°C to remove the added dispersant, binder, and lubricant, a slurry for forming a high-resistance layer prepared in advance was applied to the calcined body at 1020°C using a spray gun.

The slurry for forming a high resistance layer was prepared as follows, and t=, bismuth oxide (BizO3), ferric monide (Fe
203), pure water was added to antimony oxide (Sb203) to make a suitable slurry. At this time, by adding about 0.1 wt% of a binder such as polyvinyl alcohol, the bullet holes in the coating film increased. Heat this element to 1050-1300℃
It was fired at a temperature of Both surfaces of the thus obtained sintered element 7j were polished, and electrodes 3 were formed by spraying aluminum to obtain a voltage nonlinear resistor.

The withstand voltage characteristics when a large current pulse is applied to this voltage nonlinear resistor (here, a value that does not cause side flashing when applied twice with a 4 × 10 microsecond waveform) and the formation of the coated high resistance layer Furthermore, the relationship between the rate of change of ΔV10 μA in the opposite direction to the application direction after applying a current of 10 KA 20 times with a waveform of 8 × 20 microseconds and the composition of the slurry for forming a high-resistance layer. Examples and comparative examples are shown in Table (1)
)It was shown to. The values shown here are based on the firing temperature of 1150°C.
belongs to.

In addition, Fig. 2 shows F when Bi203 is fixed at 10 mol%.
The relationship between the composition ratio of e2us and 5b203 and withstand voltage characteristics is
FIG. 3 shows the relationship between Bi2O3 amount and withstand voltage characteristics when fixed to Fez 03 /Sbz 03-4.

As is clear from Table (1), the device coated with epoxy resin or without paste coating causes creeping flash at a current of 10 KA or less, whereas the device according to the present invention is far superior. It can be seen that it has good withstand voltage characteristics.

In addition, the conventionally known Zny 5b20+2/Zn2
The product coated with the composition of 51o4=0.25 had voltage resistance characteristics sufficient for practical use, but the rate of change in varistor voltage due to pulse application was a little noticeable. Also, according to Table (I) and Figure 2.3, the total sum is 10
In a composition of 0 mol%, Bi20a is 0.3-20 mol%
, Fe2O3 is 5-95 mol%, 5b2o3 is 5-50
It is clear that if the mol% is outside the range, the desired properties will not be exhibited.

Next, when we measured the m-degree distribution of components on the sides of these elements using an X-ray microanalyzer, the presence of at least iron and antimony was confirmed, indicating that the IC,
, the amount is Fe2 at a depth of 10 μm, respectively.
It was found that in terms of O3 and 3b20a, the nonlinear resistor of the present invention contains 5 mol% or more and 1 mol% or more. Bismuth oxide is thought to act as a flux and promote the diffusion of iron oxide and antimony oxide or the reaction with zinc oxide. Iron and antimony diffused into the element body by bismuth oxide react with zinc oxide and the like to form a high-resistance layer, improving voltage resistance and pulse resistance.

According to the above examples, it can be seen that the nonlinear resistor of the present invention has excellent withstand voltage characteristics, has a small rate of change with respect to large current pulses, and exhibits extremely excellent stability. This guarantees exceptional reliability when the device is used in a power surge arrester, etc., and is important from a practical standpoint.

In the examples of the present invention, an oxide was used as a raw material, but any material may be used as long as it becomes an oxide when sintered, such as hydroxide, carbonate, oxalate, etc. Needless to say, it is effective. In addition to the additives shown in the examples, other components may be added for the purpose of improving the characteristics of the non-linear resistor. It is desirable to bake a glass component or the like onto the outside of the glass.

Furthermore, in this example, the high-resistance layer-forming substance was applied to the calcined element body, but the same effect was observed even if it was applied to a molded element body. According to the present invention, the sintered composite mainly composed of zinc oxide and having voltage nonlinearity contains bismuth oxide, iron oxide, and antimony 81203 on the side surface of the molded element.
．． Converted to Fe2O3, 5b203, each 0.3
-20 mol%, 50-95 mol%, and 5-50 mol%, with a total of 100 mol%. By forming a high-resistance layer, withstanding voltage characteristics and high power pulse A highly reliable voltage non-core resistor with excellent characteristics can be provided.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the structure of the non-linear resistor according to the present invention, the second factor is a graph showing the ratio of Fe2e3 and 5b203 and withstand voltage characteristics, and Fig. 3 shows the relationship between the amount of Bi2O3 added and withstand voltage characteristics. This is a graph showing. DESCRIPTION OF SYMBOLS 1... Sintered element body, 2... High resistance layer, 3... Electrode. Applicant Tokyo Shibaura Electric Co., Ltd. Agent Patent Attorney Hikaru Mizuuchi Figure 1 Figure 2 5b 203 0 26 40 60 80 TOO-H
/L-% Figure 3 10 20 30 40 mol 6 m j 20B Procedural Amendment Mutual April 19, 1985 Mr. Commissioner of the Japan Patent Office 1, Indication of Case 1982 Patent Application No. 59462 2, Title of Invention Linear resistor 3, relationship with the case of the person making the amendment Patent applicant Toshiba Corporation 4, agent 1-1-17 Akasaka, Minato-ku, Tokyo Name changed on April 2, 1980 (Blank 6, contents of amendment) (1) The statement of the claims on page 1 of the specification is corrected as shown in the attached sheet. (2) "By the composition" in line 13 of page 4 is corrected to "using the composition". (3) In the same, page 5, line 1, "both sides" is corrected to "side". (4) In the same, page 10, line 18, [by a composition with the total sum reduced to 100 mol%] lc] is corrected to ``Contains Fe.sb using materials with a composition ratio of 100 mol% in total.'' L 2, Claims (1) Zinc oxide having voltage nonlinearity In a non-linear resistor in which a high resistance layer is formed on the side surface of an element body as a main component, the high resistance layer contains bismuth oxide, iron oxide, and antimony, respectively, in terms of Bi20a, Fez O3, and 5b203. 3 to 20 mol%, 50 to 95 mol%,
1. A non-linear resistor characterized in that it contains composition 1 in which the total amount is 100 mol% within the range of 5 to 50 mol%. (2) The high-resistance layer is formed by applying a slurry-like composition to the side surface of a sintered element whose main component is zinc oxide, and then sintering the composition. Nonlinear resistor according to item 1.

Claims (2)

[Claims] (1) In a nonlinear resistor in which a high resistance layer is formed on the side surface of an element body mainly composed of zinc oxide having voltage nonlinearity, the high resistance layer contains bismuth oxide, iron oxide, and antimony. , converted to Fe203.5b203,
0.3-20 mol%, 50-95 mol%, 5-95 mol%, respectively
A non-linear resistor characterized in that it is formed of a composition in which the total amount is 100 mol% within a range of 50 mol%. (2) The high-resistance layer is formed by applying a slurry composition to the side surface of a sintered element whose main component is zinc oxide and then sintering it. A nonlinear resistor according to range 1.