JPH10223410A - Production of voltage nonlinear resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the operation starting voltage by admixing granular powder principally comprising zinc oxide with a silicon oxide, forming the mixture into a predetermined shape and firing, and then forming at least a pair of electrodes on the surface of the sintered body. SOLUTION: Material powder principally comprising ZnO powder is added with pure water, a binder and a dispersing and mixed sufficiently by means of a ball mill to produce slurry from which is granular powder is produced. The granular powder is mixed with 0.5-5.0mol% of silicon having mean grain size of 1-10 microns in a state of silicon oxide powder and then added with pure water until the water content of 0.5-2.5wt.% is attained. It is then mixed and compression molded to obtain a molding. Subsequently, the molding is sintered and silver paste is printed to the opposite end faces thereof and an electrode is formed by heat treatment thus obtaining a voltage nonlinear resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a voltage nonlinear resistor incorporated in, for example, a zinc oxide surge arrester.

[0002]

2. Description of the Related Art When a voltage non-linear resistor is used for a lightning arrester, voltage non-linear resistors are connected in series or in parallel as necessary to cope with the voltage of a transmission and distribution line.

A conventional voltage non-linear resistor is obtained by first adding zinc oxide as a main component, a small amount of pulverized metal oxide such as silicon oxide and bismuth oxide as an auxiliary component, and mixing with an organic binder solution. The slurry-like raw material is spray-dried into granulated powder, and then the moisture content of the granulated powder is adjusted to form a predetermined shape, and the formed body is degreased and pre-fired to obtain a base body. A high resistance layer was formed on the side surface of the element body, fired to form a sintered body, and finally electrodes were formed on both surfaces of the sintered body.

[0004]

In the surge arrester, when the number of connected voltage non-linear resistors increases, the surge arrester not only increases in size but also causes imbalance in current sharing. As a countermeasure, it is desired to increase the operation start voltage of the voltage non-linear resistor.

[0005] The operation starting voltage of the voltage non-linear resistor is mainly determined by the type and amount of the additive. Silicon oxide is known as one of the elements that promotes an increase in the operation start voltage, but the viscosity of the slurry when mixed and pulverized varies depending on parameters such as the amount of silicon oxide added and the particle diameter. In the above-mentioned manufacturing method, there is a problem that if the amount of addition required for the characteristics is mixed, the slurry is gelled, and a voltage non-linear resistor cannot be manufactured.

Accordingly, an object of the present invention is to provide a voltage non-linear resistor having an improved operation start voltage.

[0007]

In order to achieve this object, a method for manufacturing a voltage non-linear resistor according to the present invention comprises adding a silicon compound to granulated powder containing zinc oxide as a main component to form a predetermined shape. Molding to obtain a molded body, then firing the molded body to obtain a sintered body, and then forming at least a pair of electrodes on the surface of the sintered body, granulation Since the silicon compound is added to the powder, the silicon compound required for the characteristics can be added without causing the slurry to gel, so that a voltage non-linear resistor having a high operation starting voltage can be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a step of adding a silicon compound to a granulated powder containing zinc oxide as a main component and molding it into a predetermined shape to obtain a molded article; A step of firing the molded body to obtain a sintered body, and then a step of forming at least a pair of electrodes on the surface of the sintered body, a method of manufacturing a voltage non-linear resistor, the operation start voltage is high A voltage non-linear resistor can be obtained.

The invention according to claim 2 is characterized in that the average particle size is 1 to 1
The method for producing a voltage non-linear resistor according to claim 1, wherein a silicon compound having a thickness of 0 µm is used, and a molded article can be obtained under the same molding conditions as in the related art.

According to a third aspect of the present invention, there is provided a method for manufacturing a voltage nonlinear resistor according to the first aspect, wherein the silicon compound is added in an amount of 0.5 to 5.0 mol%. Yes, the operation start voltage of the voltage non-linear resistor can be improved.

According to a fourth aspect of the present invention, after the addition of the silicon compound, the water content is adjusted so that the water content becomes 0.5 to 2.5% by weight. This is a method for manufacturing a body, and can prevent deterioration of discharge withstand characteristics.

Hereinafter, an embodiment of the present invention will be described. (Embodiment) First, the total amount of the raw material powder was set to 100 mol%.
, 0.5 mol% of bismuth, 0.2 mol% of cobalt, 0.5 mol% of manganese, 1.0 mol% of antimony, 0.5 mol% of chromium
Mol%, nickel 1.0 mol%, aluminum 5 × 10
Each metal oxide powder was weighed and added so as to be ^-3 mol% and boron 2 × 10 ^-2 mol%. At this time, it is desirable to add boron in a glass state such as bismuth borosilicate from the viewpoint of dispersibility. Next, pure water, a binder, and a dispersant were added to the raw material powder, and the mixture was sufficiently mixed with a ball mill to obtain a slurry. Next, this slurry was spray-dried and granulated using a spray drier,
A granulated powder of 00 to 200 μm was obtained. Thereafter, 0.5 mol% of silicon having an average particle diameter of 1 to 10 μm to 1
After mixing 0.0 mol% in the state of silicon oxide powder, pure water was added so that the water content became 1.0% by weight, and the mixture was mixed for 30 minutes by a V blender mixer.

It is preferable to adjust the water content at this time so as to be 0.5 to 2.5% by weight. The density is set to a moderately high value. By adjusting the density of the compact, the proportion of pores in the sintered body can be reduced, and the deterioration of the discharge withstand characteristics can be prevented. Even if silicon oxide is added in a powder state by adjusting the water content, there is no problem in dispersibility.

Next, the granulated powder containing the silicon oxide powder is added.
Adjust the water content so that the water content is 0.5 to 2.5% by weight.
After performing, 400 kg in size of 25 mm in diameter and 7 mm in thickness
/cm ^ThreeTo obtain a molded body.

Next, after removing the organic components from the molded body, the molded body was preliminarily calcined at 900 ° C. for 3 hours at a temperature rising / falling rate of 100 ° C./h to obtain a calcined body. An oxide paste that becomes a high-resistance layer by heat treatment was applied to the side surface of the calcined body, followed by main firing to obtain a sintered body having a high-resistance layer on the side surface.
This high resistance layer is to increase the insulation resistance of the side part,
It is intended to prevent creeping on the surface and improve the discharge resistance.

Next, a silver paste was printed on both end surfaces of the sintered body and heat-treated at a temperature of 500 ° C. for 1 hour to form electrodes, thereby obtaining a voltage non-linear resistor.

As a comparative example, as in the prior art, silicon oxide was mixed with other metal oxides in a content of 0.5 to
2.0 mol% was added, and the subsequent steps were the same as in the present embodiment to obtain a voltage non-linear resistor of a comparative example. Here, when silicon oxide was added in an amount of 2.5 mol% or more, the slurry gelled, and a voltage non-linear resistor could not be obtained.

Table 1 shows the operation starting voltage and voltage ratio characteristics (VmA / V10 μA) of the voltage non-linear resistor according to the present embodiment and the comparative example.

[0019]

[Table 1]

Here, V1 mA and V10 μA were measured using a DC constant current power supply. As is clear from Table 1, the voltage non-linear resistor according to the present embodiment changes the operation start voltage proportionally by adding silicon oxide in the range of 0.5 to 5.0 mol%. Can be done. In addition, even in the conventional case, even when the amount of silicon oxide added such that the slurry gels is large, a voltage non-linear resistor can be manufactured, and a resistor having a high operation starting voltage can be obtained.

In this embodiment, the addition of subcomponent metal elements such as silicon is performed in the form of an oxide. However, any compound may be used as long as it can be converted into an oxide by firing. I don't care.

Further, although the green body was pre-fired, the pre-fire may not be performed. In this case, after sintering the molded body to obtain a sintered body, an oxide paste to be a high-resistance layer is applied to the side surface of the sintered body and heat-treated to form a high-resistance layer.

[0023]

As described above, by using the method for manufacturing a voltage non-linear resistor of the present invention, a voltage non-linear resistor having a high operation starting voltage can be obtained using the same material as in the prior art. Further, since the operation start voltage can be changed linearly by the addition amount of silicon, a voltage non-linear resistor having a desired operation start voltage can be obtained.

As a result, the lightning arrester can be constituted by using a smaller number of voltage non-linear resistors than in the prior art, so that the lightning arrester can be downsized and the imbalance of current sharing can be prevented from occurring. .

Claims (4)

[Claims] 1. A step of adding a silicon compound to a granulated powder containing zinc oxide as a main component and molding it into a predetermined shape to obtain a molded body, and then firing this molded body to obtain a sintered body And then forming at least a pair of electrodes on the surface of the sintered body. 2. The silicon compound has an average particle size of 1 to 10 μm.
The method for manufacturing a voltage non-linear resistor according to claim 1, wherein 3. The amount of the silicon compound added is 0.5% Si.
The method for producing a voltage non-linear resistor according to claim 1, wherein the content of the non-linear resistor is set to be about 5.0 mol%. 4. The method for producing a voltage non-linear resistor according to claim 1, wherein after adding the silicon compound, the water content is adjusted so that the water content becomes 0.5 to 2.5% by weight.