JPS63132402A - Manufacture of 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] (Object of the Invention) (Field of Industrial Application) The present invention relates to a non-linear resistor mainly composed of zinc oxide used in lightning arresters, etc. ! ! The present invention relates to a manufacturing method of a nonlinear resistor, and in particular to a method of manufacturing a nonlinear resistor in which the dispersibility of a trace amount of 8 added to zinc oxide is improved.

(Prior art) A voltage nonlinear resistor is generally called a varistor, and its collapsed nonlinear voltage-current characteristics are utilized and it is widely used in lightning arresters and surge absorbers for the purpose of voltage stabilization or surge absorption. has been done.

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, Kobal 1~, manganese, chromium, etc. are added, mixed, granulated and formed, and then fired at high temperature in the air. ¥ for your body! The sintered body consists of a grain boundary layer formed by zinc oxide particles and additives surrounding them. It is believed that the excellent non-linear resistance characteristics are due to the interface between the zinc oxide particles and the grain boundary layer, and it has many features such as the ability to arbitrarily adjust the voltage-current characteristics to some extent.

(Problems to be Solved by the Invention) By the way, the use of these zinc oxide type varistors as power surge arresters has the following drawbacks.

In recent years, in order to reduce the construction costs of power transmission and substation facilities, there has been a demand for ultra-high transmission voltages and lower I8 edge protection levels.
On the other hand, regarding lightning arrester elements, (g) Improving non-linear characteristics, ■ Changing the addition level of additives that cause at most whitening at high charge rates, Q9 Adding new additives (→Especially improving life characteristics) For this reason, methods such as adding glass containing TJ'A oxide have been adopted.

(Special Publication No. 58-11084> Shikashi 0)~Jin) method can improve one of the non-linear characteristics or the speed characteristics, but at that time the other characteristic tends to worsen, and both characteristics can be improved at the same time. It was difficult to do. In addition, recent research has shown an example of improving moisture resistance by adding component B in an aqueous solution (Japanese Unexamined Patent Publication No. 60-2231).
01> etc. However, it has become clear that it has one drawback. That is, the life characteristics vary between manufacturing lofts and elements, that is, there is large variation in life. This poses a major problem in terms of stable industrial production of lightning arrester elements.

The present invention was made in view of the above-mentioned needs, and provides a method for manufacturing a non-linear resistor with stable life characteristics.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention uses zinc oxide as the main component, adds Bi2O3, 5b2O3, etc. as subcomponents, and mixes, molds, and sinters the mixture. In the step of obtaining a sintered body having non-ohmic properties by sintering, at least B is
It is characterized in that other additives are mixed into a mixed powder of ZnO and B2O3, which contains at least 11,000 PP in terms of 2O3 and is obtained by caulking and mixing only the main components, lnO and B2O3, and spray drying.

(Function) By this method, a nonlinear resistor with stable life characteristics and good nonlinear characteristics can be obtained by uniformly dispersing B, which has a slight effect on life characteristics, among other components. .

(Embodiment of the Invention) An embodiment of the present invention will be described in detail below. Oxidation +1:
'Sumas (BtzO3>, cobalt oxide (CO304)
, 1.0 mol% of manganese oxide ()1nO), 1.0 mol% of antimony oxide (S□b2O3), and 1% of nickel oxide (Nip).
．． 5 mol%, silicon oxide (Si02), chromium oxide (Cr
0.5 mol% of aluminum oxide (#22O
3) is 0.004 mol% and the rest is zinc oxide (ZnO)
and weigh accurately. Furthermore, a trace amount of boron oxide (B2O3
) is also weighed.

To manufacture a non-linear resistor with such a configuration, first, zinc oxide (ZnO) powder and boron oxide (B2O3) are placed in a mixing device with water and a dispersant, mixed for a predetermined period of time, and this mixture is dried in a spray dryer. Granulated. Put this granulated powder and other additives into the mixing device again, add water, dispersant, binder, and FA.
The mixture was thoroughly mixed with a crushing agent and granulated again using a spray dryer. At this time, since the initial granulated powder of a mixture of ZnO and B2O3 did not contain a binder, it was easily loosened by a mixing device, and while maintaining uniform mixing of ZnO and B2O3, it was sufficiently mixed with other additives. This powder is pressed to a diameter of 50 m and a thickness of 30 m.
It was molded into a disc for shoes. After baking at 500"C in air to remove the added dispersant, binder, and lubricant, 102O
A previously prepared slurry for forming a high resistance layer was applied to the element body calcined in 'C using a spray gun.

This element body was fired at a temperature of 120°C in an air atmosphere. Both surfaces of the sintered body thus obtained were layered in parallel to form electrodes by thermal spraying aluminum to a thickness of 20m to obtain a voltage nonlinear resistor.

Here, the nonlinear characteristic was determined as VI KA/V 1 mA. Furthermore, the life characteristics IR/IRQ are at a temperature of 120°C.
, the voltage was applied for 200 hours at a charging N rate of 9596, and was calculated from the following formula.

The nonlinear characteristics showed a good value of 1.40±0.02 in both the conventional example and the example.

FIG. 1 shows IR/IRQ due to charging as a life characteristic. This is g! This shows the stability of the element due to electric current.The conventional example υ in which B2O3 is mixed with lno and other additives, and the ln obtained by mixing only ZnO and B2O3.
Ten samples of Example 1, in which a mixture of O, B2O3 was mixed with other additives, were tested under the conditions described above. According to this, it can be seen that in the example, there was little variation between samples, all the samples were stable, and also showed good life characteristics.

On the other hand, in the conventional example, it was found that only one out of ten samples (NO7) showed good life characteristics, but the remaining nine had IR/IRQ greater than 1.0 and large variations. That is, the conventional method of directly mixing a small amount of B2O3 with a large amount of ZnO and other additives at once has a high defect rate, which is a serious problem in manufacturing sites where stable production is desired. On the other hand, it was found that the example of the present invention in which a slight amount of B2O3 was dispersed in lnO in advance and then mixed with other additives exhibited stable life characteristics.

Although the direct cause of the stable life characteristics of the embodiments of the present invention is not clear, the following can be roughly considered. Through past research, it is known that addition of a component that forms a glass phase is effective in improving or stabilizing the life characteristics of most compositions of nonlinear resistors containing ZnO as a main component. However, as shown in the conventional examples, there are various problems such as deterioration or large variations in life characteristics, and the reality is that no product with satisfactory life characteristics has been obtained. This is thought to be largely due to the fact that the total amount of components forming the glass phase, which is effective in improving life characteristics, is 1r'1tfl, which is at most 1000 PPM or less. In other words, a major factor is that it is difficult to sufficiently uniformly disperse the components forming the very fine glass phase with other components in the mixing process.

Therefore, an element with relatively good dispersion will have good life characteristics, but an element with poor dispersion will have poor life characteristics.

The present invention focuses on this problem of dispersibility, and the present invention has focused on this problem of dispersibility.
By sufficiently mixing only ZnO and B2O3 to obtain a homogeneous mixture of ZnO and B2O3, and then mixing other additives, the dispersibility of the components that form a small amount of glass phase becomes better and the life characteristics become stable. Dew.

Note that simply increasing the amount of the glass phase component added only worsens the nonlinear characteristics and does not improve the life characteristics, so this is not the only solution.

In addition, in the example, an example using boron oxide (B2O3) was shown, but in a comparative experiment using water-soluble boric acid (83BO3), the conventional example was almost unchanged, although the variation was slightly improved. It was also confirmed that the examples of the present invention exhibited excellent stability.

(Effects of the Invention) As explained above, according to the present invention, it is possible to obtain a nonlinear resistor that is excellent in both nonlinear characteristics and life characteristics. Therefore, it is suitable for use in lightning arrester elements that require excellent nonlinear characteristics and stable life characteristics at high charging rates, such as those used in ultra-high voltage power transmission.

[Brief explanation of the drawing]

The figure shows the distribution of lifetime characteristics for each element according to an embodiment of the present invention. Agent Patent Attorney Nori Chika Yudo Hirofumi Mitsumata

Claims (1)

[Claims] ZnO as a main component and at least boron (B) as a subcomponent
is converted to boron oxide (B_2O_3) and is 1000PPM
Contains the following, the main ingredients are zinc oxide (ZnO) and B_2O
A method for manufacturing a voltage nonlinear resistor, characterized in that a mixed powder of ZnO and B_2O_3 obtained by mixing only ZnO and B_2O_3 and spray drying the mixture and other additive components is mixed.