JPS59214204A - 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 When sintering a mixture containing zinc oxide as a main component and additives such as bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, chromium oxide, and silicon dioxide, The present invention relates to a voltage nonlinear resistor added with.

In recent years, zinc oxide has been used as the main component, and bisV oxide,
[A:! A voltage nonlinear resistor is a voltage nonlinear resistor made of a sintered body formed and fired by adding additives such as Hult, antimony oxide, manganese oxide, chromium oxide, and silicon dioxide, as well as boron oxide, lead oxide, and aluminum oxide as necessary. Widely used in stabilizing elements, surge absorbers, arresters, etc. In the above-mentioned voltage nonlinear resistor, zinc oxide particles are surrounded by another boundary layer (grain boundary layer) mainly composed of bismuth oxide having high resistance, so to speak, the zinc oxide is covered with the grain boundary layer. It has a structure that resembles two connected in series and parallel, and when a voltage of 1[( It is thought that voltage nonlinear resistance develops.

In general, the voltage-current characteristics of a voltage nonlinear resistor can be approximated by the formula (1): % Formula % (1) (In the formula, engineering is the current, k is a constant, ■ is the voltage, and α is the nonlinear coefficient. ). The voltage nonlinear resistor mainly composed of zinc oxide has an α value of 5 to 60, which is considerably larger than the α value of the conventional voltage nonlinear resistor made of silicon carbide, which is 6 to 4. In addition, in a region where the current-voltage characteristics are flat, the voltage applied between the zinc oxide particles is almost constant, so simply changing the thickness of the voltage nonlinear resistor can reduce the voltage required to flow 1 mA of current ( It has the characteristic of being able to freely change the current (hereinafter referred to as 1mA), and its uses are being expanded more and more.

However, even with elements made from voltage non-linear resistors that have the above-mentioned advantages, if a constant DC or AC voltage is continuously applied, the leakage current flowing through the element generally increases over time, resulting in an increase in leakage current. There is a limit to the lifespan of these devices, such as thermal runaway due to the heat generated by the devices, which eventually leads to device destruction. In particular, in the case of gapless zinc oxide type lightning arresters, a constant voltage is constantly applied, so element destruction due to increased leakage current is an extremely important problem.
In other words, it is desirable to have a long-life element in which the leakage current and the change over time in which the leakage current increases are as small as possible.

Conventionally, various glass compositions have been added to a mixture containing zinc oxide as a main component for producing voltage nonlinear resistors, with the aim of improving the energized life characteristics of voltage nonlinear resistor elements. Considerations have been made to improve the firing process, but although the results are effective for the charging life characteristics, for example, the limiting voltage ratio (which shows nonlinearity in a large current range) 1Q current to non-linear resistor element
V is the ratio of the voltage required to flow kA to the voltage required to flow 1mA. They often have drawbacks such as a large value of kA/vl (often used), and do not fully satisfy the characteristics required of power surge arresters.

The inventors of the present invention have conducted extensive research to eliminate the blemish point in electrical characteristics such as the voltage application life characteristics and limiting voltage ratio of voltage nonlinear resistor elements as described above, and as a result, we have found that When sintering a mixture containing bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, chromium oxide, and silicon dioxide as additives, zinc oxide and boron oxide are each added in an amount of 40 to 65% (by weight, the same applies hereinafter). ) and a glass containing 25 to 40% of one or more selected from the group consisting of titanium oxide, zirconium oxide, tantalum oxide, lanthanum oxide, and yttrium oxide to 100 parts (parts by weight, the same applies hereinafter) of the mixture. By adding 0.004 to 0.6 parts to the voltage nonlinear resistor to create a voltage nonlinear resistor, it is possible to improve the electrical properties such as the energized life characteristics and limiting voltage ratio of the conventionally used voltage nonlinear resistor element. The problem was solved and the present invention was completed.

Zinc oxide (ZnO), bismuth oxide (B
1203), cobalt oxide (00203), manganese oxide examples. 2) Chromium oxide (or2o3), antimony oxide (sb2o3), and silicon dioxide (Sin2) are powders with a purity of about 99% or more, and these powders are mixed, and if necessary, boron oxide and silicon dioxide A mixture based on zinc oxide is prepared with addition of additives such as aluminum.

Zinc leadide used in the production of glass used in the present invention,
Boron oxide (B203), titanium oxide (TiO2),
Zirconium oxide (ZrO2), tantalum oxide (Tag
O5), lanthanum oxide (Lago3), and yttrium oxide (Y2O2) are powders each having an Ikgt of 99% or more, and boron oxide is preferably sufficiently dried and does not contain metaboric acid. The ratio of their use is 40-65% and 25-40%, respectively, of zinc oxide and boron oxide, which are always included in glass, and titanium oxide, zirconium oxide, tantalum oxide, lanthanum oxide, and yttrium oxide. The remaining amount is one or more compounds selected from the group consisting of: The preferred contents of titanium oxide, zirconium oxide, tantalum oxide, lanthanum oxide, and yttrium oxide contained in the glass are 1 to 10% and 0.7%, respectively, based on the total amount of the glass.
~18%, 1-65%, 1-65% and 1-25%. The proportions of zinc oxide and boron oxide, which are always included in the above glass, are each 40 to 65%.
If it is out of the range of 25 to 40%, the effect of glass addition may be reduced because it becomes difficult to vitrify or part of it becomes a crystalline phase even after vitrification. , the limiting voltage ratio characteristics and energization life characteristics of the fabricated voltage nonlinear resistor element deteriorate, making it unsuitable as a power element.

The components for producing the glass described above may be mixed with a mixture containing zinc oxide as the main component and fired to produce a voltage nonlinear resistor. After uniformly dispersing a component that has the effect of extending the energized life of a voltage nonlinear resistor in the glass, it is made into a powder of approximately 400 mesh or less by a method such as pulverization, and the main component is zinc oxide. By mixing and sintering with a mixture that has the above effect, the components with the above effect can be uniformly distributed in the sintered body, resulting in a uniformly stabilized grain boundary layer, which further extends the energized life. The effect can be changed. It should be noted that the effect of lengthening the energized life when glass is not used as the component for manufacturing the glass is halved compared to the effect when glass is used.

The amount of glass used in the present invention is from 0.004 to 100 parts of the mixture containing zinc oxide as a main component.
0.6 parts is preferable; if the amount of the glass used is less than 0.004 parts, the effect of using the glass cannot be changed, and even if the amount used exceeds 0.6 parts, Not only does it have almost no effect on the amount used, but it also has an adverse effect on the electrical characteristics.

After mixing a predetermined amount of the above-mentioned glass with a mixture containing zinc oxide as a main component to be used in the present invention, granulation and pressure molding are carried out in a usual manner, followed by firing and heat treatment under predetermined conditions. The voltage of the non-linear resistor can be changed.

Next, the voltage nonlinear resistor of the present invention will be explained using manufacturing examples, examples, and comparative examples.

Production Example 1 Powder having the composition shown in Table 1 was melted at about 1,200 to 15,000 c for about 2 hours and then rapidly cooled to obtain glass. Table 1 Examples 1 to 7 and Comparative Examples 1 to 2 Zinc oxide, bismuth oxide, Koba oxide A with a purity of 99% or more
- Manganese oxide, chromium oxide, antimony oxide and silicon dioxide, respectively, at 9.1%, 2.7% and 0.
96%, 0.67%, 0.88%, 6.68% and 0
．． 41% mixed. To 100 parts of the resulting mixture (hereinafter referred to as mixture A), add the glass shown in Table 2 obtained in Production Example 1 in the amount shown in Table 2, mix thoroughly, and then granulate by spray drying to obtain a diameter It was pressure-formed into a 40 mm and 12 mm thick disc, and then heated at 1200°0 in air for about 2
The product was fired for an hour and then subjected to a heat treatment of 550 to 65 OoO to obtain a sintered body. The obtained sintered body J electrode was attached to produce a voltage nonlinear resistor element.

DC voltage is applied to the obtained element under the conditions that the voltage applied to the element is expressed as the applied IEIEf/voltage when jmA flows through the element, and the ambient temperature is 100°0. The change in current over time was measured. The result is the first
As shown in the figure.

In addition, the limiting voltage ratio for the obtained element is ■2.5♂.

. 2 was measured. The results are shown in Table 2.

Table 2 Glass whose main components are zinc oxide and boron oxide as shown in Figure 1? The device of Comparative Example 2, which was fabricated without the addition of glass, had large initial leakage current and changes over time in the leakage current due to direct current application, and thermal runaway occurred in a short period of time, whereas the device fabricated with the addition of glass It can be seen that the devices of Examples 1 to 5 all have a small initial leakage current due to direct current charging, a small change in leakage current over time, and a significantly improved charging life characteristic. On the other hand, the leakage current of the element of Comparative Example prepared by adding glass made of zinc oxide and boron oxide is close to the characteristics of the element of Comparative Example 2, and is large; It can be seen that the addition of glass consisting of zinc oxide and boron oxide is effective in reducing the change over time in leakage current due to direct current application to the element. Also, Comparative Example 1 and Examples 1 to 5
From comparison with glass, titanium oxide, zirconium oxide,
When tantalum oxide, lanthanum oxide, or yttrium oxide is contained, leakage current due to DC charging of the element is reduced, and the titanium oxide, zirconium oxide, tantalum oxide,
Example 6: If the composition can form a uniform glass even if it contains 22 or more types of lanthanum oxide and yttrium oxide, the leakage current due to direct current application will be reduced, and the change in leakage current over time will be reduced. From the results of ~7.

The limiting voltage ratio shown in Table 2 also shows that the elements of Examples 1 to 7 and Comparative Example 1 in which glass was added showed superior characteristics compared to the element of Comparative Example 2 in which glass was not added. It can be seen that by adding this element, the characteristics desirable for a power surge arrester can be changed.

Examples 8 to 12 and Comparative Examples 6 to 4 and 8 to 9 To 100 parts of the mixture A obtained in Example 1, glass E obtained in Production Example 1 was added in an amount shown in Table 3. A device was fabricated in the same manner as above.

Direct current was applied to the obtained device in the same manner as in Example 1, and the change over time in the leakage current flowing through the device was measured. The results are shown in Figure 2. As shown in Figure 2, the leakage current changes over time due to direct current application in the element fabricated by adding 0.005 to 0.5 parts of glass to 100 parts of mixture A. It can be seen that the voltage becomes smaller and the charging life characteristics are improved. However, the amount of glass added is 0.006
It can be seen that when the change in the leakage current becomes close to that of Comparative Example 2 in which no glass is added, the energized life characteristics are not improved much.

On the other hand, the limiting voltage ratio in the current/voltage characteristics of the element is the 6th
As shown in the table, when the amount of glass added is 0.7 parts, the material becomes poor and becomes unsuitable as a power device.

Therefore, the appropriate amount of glass added is 0.004 to 0.00.
6 parts, more preferably o, oos to 0.5 parts.

Table 6 Example 13 Examples 8 to 12 except that the glass E used in Examples 8 to 12 was changed to glass A1 glass B1 glass 0 or glass D containing titanium oxide, zirconium oxide, tantalum oxide, or lanthanum oxide. The energization life characteristics and limiting voltage ratio were measured in the same manner as in Example 8-12.

Examples 14 to 19 and Comparative Examples 5 to 7 Glasses having the glass compositions shown in Table 4 were prepared in the same manner as in Production Example 1. A device was produced in the same manner as in Example 1 by adding 0.01 part of the obtained glass to 100 parts of mixture A. Furthermore, the content of zirconium oxide in the glass is 20%.
When it became a part of the crystalline phase, it changed to glass.

Direct current was applied to the obtained device in the same manner as in Example 1, and the change over time in the leakage current flowing through the device was measured. The results are shown in FIG.

From Figure 6, the content of zirconium oxide in the glass is 1
The devices of Examples 14, 16 and 19, prepared by adding ~15% glass to Mixture A, showed a smaller change in leakage current over time, a longer energized life, and a lower limit as shown in Table 4. It can be seen that the voltage ratio characteristics are also excellent.

On the other hand, as in Comparative Example 5, the zirconium oxide content was 0.
．． If it decreases to 5%, the change in leakage current over time during DC voltage application becomes large, and the power application life becomes short. On the other hand, when the content of zirconium oxide is 20%, uniform glass cannot be formed, and the change in leakage current over time when direct current is applied to devices manufactured by adding this glass becomes large, making them unsuitable as power devices. Cylinder 4 Table Example 20 Titanium oxide, tantalum oxide, lanthanum oxide, or titanium oxide in place of zirconium oxide in Examples 14 to 19)
Using IJum, we similarly determined the change in leakage current over time and the limiting voltage ratio during direct current application.As a result, we found that the proportions of titanium oxide, tantalum oxide, lanthanum oxide, and yttrium oxide contained in the glass were 1 to 10, respectively. %, 1-3
Ranges of 5%, 1-35% and 1-25% have been found to be suitable.

Example 21 The elements obtained in Examples 1 to 20 and Comparative Examples 1 to 9 were subjected to alternating current charging in the same manner as in the case of direct current charging. As a result, it was found that when an element was prepared by adding glass, the change in leakage current over time was reduced even when AC charging was applied, as in the case of DC charging, and it exhibited good power characteristics.

[Brief explanation of drawings]

Figures 1 to 6 show the charging times when direct current was applied to an element obtained from the voltage nonlinear resistor of the present invention and an element obtained from the voltage nonlinear resistor fabricated as a comparison, respectively. FIG. Agent Masuo Oiwa (and 2 others) 1st Field Section Electricity Hours' (hr sacrifice) Figure 22 Electricity Charge Hours (hr) 3rd Field Section 1fT Observation hr”2)

Claims (2)

[Claims] (1) When sintering a mixture containing zinc oxide as the main component and additives such as bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, chromium oxide, and silicon dioxide, zinc oxide and boron oxide each contain 40 to 40% 65
% by weight and 25 to 40% by weight, and contains titanium oxide,
Glass containing one or more selected from the group consisting of zirconium oxide, tantalum oxide, lanthanum oxide, and yttrium oxide is added at a rate of 0.00% per 100 parts of the mixture.
A voltage nonlinear resistor characterized by adding a 0.004 to 0.6 thick cliff. (2) titanium oxide, zirconium oxide in the glass,
The content of tantalum oxide, lanthanum oxide and yttrium oxide is 1 to 10% by weight each based on the total amount of glass,
0.7-18% by weight, 1-65% by weight, 1-65% by weight
and 1 to 25% by weight, the voltage nonlinear resistor according to claim (1).