JPS61139004A - Non-linear 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 relates to a nonlinear resistor in which a sintered body containing zinc oxide (ZnO) as a main component itself has nonlinear voltage-current characteristics.

[Technical Background of the Invention] A voltage nonlinear resistor is generally called a varistor, and its excellent nonlinear voltage -i! ! Taking advantage of its current characteristics, it is widely used in lightning arresters and surge absorbers for the purpose of voltage stabilization or surge absorption.

A typical example is zinc oxide varistor.

The main ingredient is zinc oxide, with a small amount of bismuth,
After adding oxides such as antimony, cobalt, manganese, and chromium, mixing, granulating, and molding, it is fired at high temperature in air.
It is constructed by attaching electrodes to the sintered body.

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 thought that this is due to the interface with the voltage −
It has many features such as the ability to arbitrarily adjust the current characteristics to some extent.

To describe a typical manufacturing method of this type, the main ingredient is acid raw beans 1.
(Zn O) Hiss dioxide vs. (Bi 203 ), cobalt oxide (CO2O3), manganese dioxide (Mn 0
2), rli antimony (Sb203), chromium oxide (Cr203), silicon dioxide (S102),
Chive Oxide '7 /Ll (N i O) Su (!') Add about 0.5 to 3 m01%, and add aluminum oxide (Al2O2) and boron oxide (B2O) as needed.
i>, silver oxide (Ag20), etc. are accurately weighed, placed in a mixer, and thoroughly dispersed and mixed. After the mixture is granulated,
Form it into a disk shape, put it in a sintering container (pod) and heat it in the air for 10 minutes.
Sinter at 50-1300°C. After sintering both planes are 1~2M
It is common to polish samples with a thickness of 20 to 22 shoes. A metallicon electrode made of aluminum or the like is attached to the rough surface to form a non-linear resistor.

[Problems with Background Art] Nonlinear resistors manufactured in this manner are widely used in power surge arresters of 500 kV or less. However, I.J.
)-IV lightning arresters, which require extremely excellent non-linear characteristics, could not be said to have sufficient non-linear characteristics. Efforts have been made to improve the nonlinear characteristics by examining the component ratio, adding new components, and improving the manufacturing process, but this has been a difficult problem.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to provide a nonlinear resistor that can improve nonlinear characteristics.

[Summary of the Invention] In order to achieve the above object, according to the present invention, 0.3 to 1.5 mol% of bismuth oxide and cobalt oxide are added to zinc oxide (ZnO), which is the main component, in terms of 3i20i. 2
0.3 to 1.5 mol% in terms of 03, 0.3 to 1.5 mol% in terms of manganese oxide to MnO, and 0.5 to 2.0 mols in terms of antimony oxide to 3b203. %, nickel oxide converted to NiO, 0.5 to 2.0 mol%,
Boron oxide is converted to B2O3 and is 5X10-3 to 5x10
'2 mol%, silver oxide A! +20 converted to 2X10
-'~2X104 mol% aluminum oxide Al2
The sintered body contains 5XIO-4 to 2X104 mol% in terms of O2, and the element diameter is φ90 to φ2C)+m and the element thickness is 25 to 45 #lI in order to take into account the shape effect of the element.
The nonlinear characteristics are improved by setting l+.

[Examples of the Invention] The present invention will be described in detail below with reference to Examples. Principal component (1
) Zn 0 (7) Others: Bi 20g, CO203゜MnO, 5b20a, NiO 0.8゜0.8 each
, 0.8, 1.2, 1.2 mo1%, and further B2
O3.

Ag20. Al2O2 each 2x104゜8x10
°', 2X 10' Weigh accurately so that it becomes 1%. In order to thoroughly mix these powder raw materials, they were placed in a dispersion/mixing device together with water, a dispersant, a binder, and a lubricant to be dispersed and mixed. Next, the mixture slurry is granulated using a spray dryer so that the average particle size is, for example, 120 microns. After pressing this powder and sintering, the element diameter is φ60 to φ150m, and the thickness is t12 to t52m.
It was molded to obtain an element. In order to remove the added dispersant, binder, and lubricant in advance, it is fired in air at 500°C. Further, pre-baking is performed at 1050°C to form a high-resistance layer on the side surface, and after coating the high-resistance layer, the resulting baked product is placed in a firing container (pod) and fired at a temperature of 1100-1250'C in air. Polish both planes of the body to a thickness of 10~
A 50s+ sample was made. Then reheat at 500℃,
Aluminum metallic electrodes were attached to both planes.

The results of measuring the nonlinear characteristics of the completed nonlinear resistor are shown in FIGS. 1 and 2. The nonlinear characteristics are the voltage VIIIA when 1 mA of direct current flows through the element, and 8×
The ratio of the voltage VskA when 500OA flows with a pulse waveform of 20 μsec, that is, the limiting voltage ratio, is Vs k A /
It was indicated as V1 mA. The smaller this value is, the better the nonlinear characteristics are. As can be seen from FIG. 1, the limiting voltage ratio is better when the device is thicker than the conventional device thickness of 20 to 22#ll11, and the device thickness of 25 to 45M is particularly excellent. Moreover, from FIG. 2, as the element diameter φ is increased, the limiting voltage ratio is improved and shows the best value between φ90 and φ120.

However, when φ120a+m is exceeded, the limiting voltage ratio becomes worse.

The detailed mechanism by which the limiting voltage ratio is improved by increasing the element thickness is not clear at present, but it can be generally considered as follows. In other words, nonlinear resistors contain low melting point substances such as Bi20i and 5b203 as compositional components, but these components partially evaporate from the surface of the element during the sintering process, resulting in It is known that the composition inside and near the surface layer is slightly different. Bi2O3 and 3b 20 play an important role in imparting nonlinear characteristics.
It is expected that the evaporation of No. 3 will worsen the nonlinear characteristics near the surface layer. The proportion occupied by this surface layer decreases as the thickness of the sintered body increases, so it is thought that the thicker the sintered body is, the better the nonlinear characteristics are. However, on the other hand, if it is too thick, sintering will not proceed uniformly to the inside of the conductor, so it is quite conceivable that the thickness will naturally be limited. In the composition system described above, the maximum thickness of the sintered body was 47 m, and the thickness after polishing was 45 m.

Also, if it is possible to make an ideal element, the element diameter can be limited by increasing the element diameter in terms of current density.
The voltage ratio should be infinitely improved, but in reality, non-uniformity is promoted by increasing the element diameter, and as a result, it becomes worse at diameters larger than φ120#1l11. Then, in the composition mentioned above, the element diameter is φ90 to φ120m+
It was confirmed that good characteristics were obtained when the device thickness was 25 to 45 #.

Although oxide raw materials were used in the examples, the form of the compound does not matter as long as it can be sintered to become an oxide.

[Effect of the invention 1] In addition to the above, the nonlinear resistor obtained by using the composition according to the present invention and having an element diameter of φ90 to φ120 #l11 and a thickness of t25 to t45m+ has excellent nonlinear characteristics. In particular, when used in UHV lightning arresters, the practical value of reducing the protection level is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between element thickness and limiting voltage ratio, and FIG. 2 is a diagram showing the relationship between element diameter and limiting voltage ratio.

Claims (1)

[Claims] Bi_2 with bismuth oxide in the main component zinc oxide (ZnO)
0.3 to 1.5 mol% in terms of O_3, 0.3 to 1.5 mol% in terms of cobalt oxide as Co_2O_3, 0.3 to 1.5 mol% in terms of manganese oxide as MnO. ,
Antimony oxide converted to Sb_2O_3 is 0.3 to 2
．． 0 mol%, nickel oxide converted to NiO is 0.5~
2.0 mol%, boron oxide converted to B_2O_3, 5×
10^-^3 to 5 x 10^-^2 mol%, silver oxide to Ag
_Converted to 2O 2 x 10^-^3 ~ 2 x 10^-^2
A sintered body containing aluminum oxide in an amount of 5 x 10^-^4 to 2 x 10^-^2 mol% in terms of Al_2O_3, the element diameter is φ90 to φ120 mm, and the element thickness is 25 to 45 mm. A non-linear resistor characterized by: