JPS60169103A - Voltage 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 Field of the Invention The present invention relates to a voltage nonlinear resistor whose main component is zinc oxide.

Conventional technology In general, this type of voltage nonlinear resistor has excellent nonlinearity, so it is suitable for surge absorbers of electrical equipment, etc.ζ
I'm in two phases. The production of this type of voltage nonlinear resistor requires zinc oxide (ZnO) as the main component and bismuth oxide (
It is carried out by mixing several types of additive components including st*om) as subcomponents, molding the mixture, and then firing it. The reason why bismuth oxide is added here is that it has a lower melting point than zinc oxide and promotes the crystal growth of zinc oxide particles through liquid phase sintering, but conventionally, this function is not achieved. Therefore, a large amount of bismuth oxide was used, for example, 0.3 mole or more.

By the way, when manufacturing a voltage non-linear resistor, in order to improve the life characteristics of the resistor or to insulate the outer periphery of the resistor, it is necessary to heat the resistor at a temperature of 400 to 900°C after sintering.
This post-sintering heat treatment changes the crystal system of bismuth oxide. For this reason, the electrical characteristics of the voltage nonlinear resistor are greatly reduced, and the degree of this is greater as the heat treatment temperature is higher. As a result, conventional resistors can obtain good characteristics with α (nonlinear index) of 20 or more in a certain current range (for example, 100 μA to IA), but outside that range, the nonlinear index was a fairly low value. Furthermore, there are five problems with B110, which is the main component of the additive. There is also the problem that the metal component Bi has a Clarke number of 2×10-' and is a scarce resource.

Purpose of the Invention The present invention was developed based on the above background, and aims to suppress the content of Bi and O among the additive components to a trace amount, and improve various device characteristics such as nonlinear characteristics. The object of the present invention is to provide a voltage nonlinear resistor that can perform the following steps.

Summary of the Invention The first invention is characterized by containing zinc oxide (ZnO) as the main component, manganese oxide (MnO,), antimony oxide (Sb, O,), chromium oxide (CryOs), bismuth oxide (nt*os), ), and a first component containing lead oxide (p
bo) and antimony oxide (SbOs), chromium oxide (crtos), zinc oxide (ZnO), cobalt oxide≦
Co1on) and manganese oxide (MnOx).
The second component obtained by mixing and calcining the seeds and zinc borosilicate glass is mixed to form a sintered body.

Example A voltage nonlinear resistor according to an example of the present invention is made of ZnO98
, 47 mo/Ll%, MnO, 0.5 mole q6, sb, 0
．． 0.5 mo/Lt4, Cr10B 0.5 mole%,
A first component consisting of Bl, 0.0.03 mol%, and PbO
, CrtO,, sb, o, in a molar ratio of 4:1:1. 2% by weight and 0.2% by weight of zinc borosilicate glass and sintered.

Two specific examples of manufacturing such a resistor are as follows:
First, PbO, Cr, O@, Sb, 0. A predetermined amount of each powder was weighed in the above ratio, thoroughly mixed in a centrifugal ball mill, and then heated in an aluminum pot at a temperature of 1000°C for 4 hours.
After calcining for a period of time, the calcined powder obtained is pulverized in a centrifugal ball mill to obtain a reaction product as a second component.

On the other hand, ZnO, B110@, Mn0tr sb, o,,
Weigh out a predetermined amount of each powder of Crt's in the above ratio, add 2% by weight and 0.2% by weight of the above reaction product and zinc borosilicate glass, respectively, and then thoroughly mix with a rotating ball mill, Shape into a disc. Next, the molded body was fired in air at a temperature of 1130°C for 6 hours, then both end faces of the obtained sintered body were polished, Ag electrodes were applied to both end faces, and heat treatment was performed at a temperature of 590°C for 1 hour. Thus, a voltage nonlinear resistor is obtained. Here pbo, sb, o, .

By calcining the mixture of Cr@0@, a reactant containing pyrochlore crystals as a main component can be obtained. In order to investigate this, the material was soaked in the above calcined powder and subjected to X-ray diffraction, and the result was an X-ray diffraction pattern as shown in FIG. This shows that the main component of the reactant is pyrochlore crystals.

Next (2) Comparison of element 41 between the voltage nonlinear resistor actually manufactured as described above (this is referred to as resistor A) and a conventional resistor whose main additive is B110. Fig. 2 is a graph showing voltage-current characteristics with current on the horizontal axis and voltage on the vertical axis, and Fig. 3 shows the relationship between heat treatment temperature and rate of change in v1rILA/■ and α before and after heat treatment. This graph shows the relationship between the two heat treatment temperatures on the horizontal axis and the rate of change on the vertical axis. It shows the rate of increase in leakage current when applying
It is a graph in which the horizontal axis represents the voltage application time and the vertical axis represents the rate of increase in leakage current. Figures 2 to 4 (1 and 2 in 2 indicate the characteristics of resistor A and a conventional resistor, respectively.

Also V 1 mA/l! 1 ml is the voltage across a resistor with a thickness of 1 mA when a current of 1 mA is passed through it, and α is the voltage across the resistor when a current of I (A) is passed through the resistor (V (v)
If the voltage is generated, I=(-¥:)ct is an index. K is a nonlinear resistance. Also this α
varies depending on the current value, but generally 0.1 mA to 1 m
The value when a current in the range of A is applied is often used,
In the following, values within this range will be adopted.

First, looking at FIG. 2, the slope is smaller than the slope of curve 2 in the microcurrent region and the large current region. Here, α increases as the slope of the curve in FIG. 2 decreases, so in the micro current region and large current region,
It is understood that α is larger than that of the conventional resistor, and the nonlinear characteristics are superior. Also, looking at Figure 3, in the conventional resistor, v1rnA/, 11
．． When the heat treatment temperature becomes higher than around 500°C, both of , and α hardly change due to heat treatment, indicating that the characteristics do not deteriorate. The curve indicated by 1' in FIG. 3 will be described later. Further, referring to FIG. 4, it can be seen that the resistor A of the example has a smaller rate of increase in leakage current than the conventional resistor, and has good life characteristics.

Figure 5 is a graph examining how v1fiA, /- and α change when the content ratio of zinc borosilicate glass is changed.
1 indicates a change in α. However, the other additive components have the same composition as in the example. From this result, in order to obtain good 71" characteristics, for zinc borosilicate glass, it is necessary to
It is necessary that it be contained at a content rate of 5% by weight (content rate relative to the whole). Also, MnO,, Sb, 0. ,
Crt03. Similar measurements were made for
Good 72: It was found that in order to obtain the characteristics, it is necessary to contain each component at a content ratio of 0.1 to 5 moles (relative to the first component). Similar measurements were performed on the reaction products, and it was found that in order to obtain good characteristics, the
It has been found that it is necessary to contain it at a content rate of 20% by weight (relative to the total weight).

Regarding the blending ratio of the above reaction products, PbO.

Any compound that forms pyrochlore crystals containing sb, o, and is not limited to the blending ratio shown in the examples. Also, regarding its composition, pbo.

In addition to the combination of Sb Minoo OH and Cr10g, pbo, sb, and o.

A similar effect can be obtained by a combination of at least one of Cr, OB, ZnO, Co, OB, and MnO. The temporary φ temperature and the calcination time in the calcination step to obtain the above reaction product are respectively 800 to 1
The temperature is preferably 100°C for 1 to 10 hours.

The reason for this is that if the calcination temperature is lower than 800°C or the calcination time is shorter than 1 hour, the reaction will not occur sufficiently, and if the calcination temperature is higher than 1100°C or the calcination time is shorter than 10 hours. This is because if the length is too long, the degree of PbO volatilization will increase and the nonlinear characteristics will deteriorate.

The firing temperature and firing time in the firing step after mixing the first component and the second component are preferably 950 to 1350°C and 1 to 20 hours, respectively. The reason is that the firing temperature is 95
If the temperature is lower than 0°C or the firing time is shorter than 1 hour, a dense and uniform sintered body cannot be obtained;
This is because if the temperature is higher than 50° C. or the firing time is longer than 20 hours, the degree of volatilization of PbO, Bi, and O near the surface will be large, resulting in poor nonlinear characteristics.

Here, talking about the roles of Bi, O, and Figure 6 shows the relationship between the firing temperature in the firing process after mixing the first component and the second component, and α and v17rQ/1m.
0. The solid lines 3 and 4 show the results of the investigation with and without the addition of Bi.
, O, is added to V8, (change in α
The solid lines 5 and 6 show the change in v1mA/1111 and the change in α for the case where Bi and 0° are not added, respectively. In this case of the resistor! The other additive components are the same as those for resistor A. As is clear from the figure, a trace amount of B
l, 0. By adding , the optimum firing temperature range can be expanded. In order to obtain the effect of expanding the optimum firing temperature, Bi, 0. The content ratio of is 0.0
It needs to be 11 or more. The reason for such an effect is thought to be that 110 g of B and the reaction product were added in combination. On the other hand, Bi, 01
As the content ratio of α increases, the rate of decrease in α after heat treatment increases, and the degree of decrease increases as the heat treatment temperature increases. The solid line 1' in FIG. 3 indicates Bi, 0. The rate of change in α is shown when 0.1 mol of Bi is added, and when this solid line 1' is compared with the solid line 1 (addition of 0.0.03 mol of Bi), it is found that when Bi2O2 is added by 0.1 mol, The one with molar addition is more Bi,
0. The rate of decrease in α is greater than that in which 0.03 molt of is added. And solid line 1' and solid line 2. (Conventional resistor), the one with 0.1 mol of Bi and O added has better characteristics than the conventional resistor, but Bi,
0. If the content exceeds 0.1 molt, the properties will approach those of conventional products and the effectiveness will diminish. Therefore, it is necessary that the content ratio of Bi and O is in the range of 0.01 to 0.1 mol.

Further, the heat treatment temperature of the sintered body is preferably 500 to 850°C; if it is lower than 500°C, the life characteristics will be poor, and if it is higher than 850°C, the nonlinear characteristics will be poor.

In the above embodiments, a centrifugal ball mill and an aluminium crucible were used to manufacture the resistor, but the type of equipment may be any suitable for the purpose and is not limited to these.

Effects of the Invention As described above (2) According to the present invention, instead of using a large amount of Bi, 03 as the main component of the additive, a reaction product containing pyrochlore crystals containing PbO, Sb, and 0° as the main component is used. ,Z
With nO as the main component, MnO,, sb, o,, Cry'
s.

Since it is composed of the first component having 6A as an additive component and zinc borosilicate glass, Bi, 0. It is possible to suppress the amount of ygs to a very small amount and obtain good characteristics.

Furthermore, its characteristics are better than those of resistors containing B1101 as the main additive. That is, conventional Bi, 0.
Compared to voltage non-linear resistors that add a large amount of , the electrical properties decrease less due to heat treatment after sintering, and the electrical properties can be almost completely changed by heat treatment in the normal temperature range (400°C to 900°C) in the heat treatment process. Does not decrease. As a result, the nonlinear index in the microcurrent region and the large current region is larger than that of the conventional device, and since the nonlinear index in the microcurrent region is large, the leakage current during power application is small. Moreover, the increase in leakage current due to long-term energization is small, and a long-life surge absorbing element can be obtained.

By adding a reaction product as a second component in combination with Bi, O, etc., it is possible to widen the optimum firing temperature range, and control in the manufacturing process becomes easier.

In addition, B1101 (Clark number of Bi: 2 x 10") is more advantageous in terms of resources than when a large amount of C is present in two phases. The reason is that among the metal components used as additive components, those with a small Clark number are Co. (Kura'Z number 4XIQ-8),
Pb (ri5-1 number 1.5X10-''), sb (Clarke number 5X10-'), among which Co, P
b is much more abundant than Bit2, and sb is B
Similar to l, the abundance is small, but like Bi in the conventional case, C
: This is because the content ratio is not large.

In addition to the above-mentioned effects, the reaction product containing PbO and a trace amount of Bl, 0. PbO, Bi, 0. There is almost no volatilization, which is advantageous in terms of occupational health and environment.

[Brief explanation of the drawing]

Figure 1 is an X-ray diffraction diagram of an example of the reaction product used in the present invention, Figure 2 is a voltage-current characteristic diagram of a voltage nonlinear resistor, and Figure 3 is a diagram of voltage-current characteristics of a voltage nonlinear resistor.
The figure shows vl and 7m versus heat treatment temperature for voltage nonlinear resistor.
Figure 4 is a graph showing the change in α and α;
The figure is a graph showing the nonlinear characteristics of the voltage nonlinear resistor with respect to the content ratio of additive components, and FIG. 6 is the graph showing the nonlinear characteristics of the voltage nonlinear resistor with respect to the firing temperature.

Claims (1)

[Claims] (1) A first component consisting of 0.1 to 5 mol of manganese oxide, 0.1 to 5 mol of antimony oxide, 0.1 to 5 mol of chromium oxide, 0.61 to 0.1 mol of bismuth oxide, and the balance zinc oxide; , a second component obtained by calcining a mixture consisting of one or more of chromium oxide, zinc oxide, cobalt oxide, and manganese oxide, and lead oxide and antimony oxide;
The content of the second component is 0.2 to 20% by weight, the content of the zinc borosilicate glass is 0.01 to 5% by weight, and the balance is the first component. A voltage nonlinear resistor characterized by: