JPH01109703A - Voltage non-linear resistor - Google Patents

Abstract

PURPOSE:To obtain a voltage non-linear resistor having desirable resistance to surge and electro-mechanical lifetime with little variance in electric characteristics, by specifying the thickness and the porosity of a metallicon electrode. CONSTITUTION:In a voltage non-linear resistor subjected to extremely large current, porosity of its metallicon electrode layer and a certain range of thicknesses thereof improve resistance to surge and electro-mechanical lifetime. The porosity of the metallicon electrode should be Y<=X/10+7 when Y is a porosity(%) and X is a thickness of the metallicon(mum). Thus, the voltage non- linear resistor is allowed to have desirable characteristics with little variance in various properties, such as resistance to surge, electro-mechanical lifetime or the like.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a voltage non-linear resistor whose main component is zinc oxide (ZnO), and in particular, the present invention relates to a voltage non-linear resistor having zinc oxide (ZnO) as a main component. This invention relates to a good voltage nonlinear resistor.

(Conventional technology) BjzO3+ 5btO has traditionally been made mainly of zinc oxide.
It is widely known that resistors containing small amounts of additives such as ：++SiO□, Co20s+ MnO2, etc. exhibit excellent voltage nonlinearity, and are used in lightning arresters etc. by taking advantage of this property. .

Especially when used as a lightning arrester, even if an excessive current flows due to a lightning strike, the current is grounded by a voltage nonlinear resistor that is normally an insulator and becomes a conductor when a voltage higher than the specified voltage is applied. Accidents caused by lightning can be prevented.

(Problems to be Solved by the Invention) In the voltage nonlinear resistor described above, in recent years, metallicon electrodes that are provided on the electrode forming surface of the sintered body by thermal spraying, for example, have poor adhesion and layer uniformity. At worst, electric field concentration occurs during lightning surges, and the current flowing through the resistor becomes non-uniform throughout the resistor, resulting in deterioration of surge resistance, charge life, and other characteristics.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a voltage nonlinear resistor with improved surge resistance and stable characteristics.

(Means for Solving the Problems) The present invention provides a voltage nonlinear resistor comprising a sintered body formed by molding and firing a mixture of metal oxides containing zinc oxide as a main component, and a metallicon electrode provided thereon. The metallicon electrode is characterized in that the porosity of the metallicon electrode satisfies Y≦□X+7, where Y is the porosity (%) and X is the metallicon thickness (μm).

(Function) The present invention resides in a voltage non-linear resistor through which a large amount of current flows, and the region consisting of the porosity and thickness of the metallicon electrode layer improves surge resistance and charging life characteristics. This was done with this in mind.

(Example) To obtain a voltage nonlinear resistor whose main component is zinc oxide,
First, zinc oxide raw material adjusted to a predetermined particle size and Bi2O adjusted to a predetermined particle size: +, Coco, , Mn0z+
5bZo:+, Cr2O3, 5tOz+ A predetermined amount of additives such as NiO are mixed. At this time, a predetermined amount of polyvinyl alcohol aqueous solution, etc. is added to these raw material powders, and after mixing, preferably using a disper mill,
Granules are preferably obtained by granulation using a spray dryer. After granulation, it is molded into a predetermined shape under a molding pressure of 800 to 1000 kg/cm.
800-1000°C holding time 1 at 0-70°C/hr
The binder is scattered and removed by pre-firing for ~5 hours.

Next, an insulating coating layer is formed on the side surface of the calcined body. In the present invention, BizO+, 5bzOz, SiO□
An oxide paste prepared by adding organic binders such as ethyl cellulose, butyl calpitol, n-butyl acetate, etc. to a predetermined amount of the above is applied to the side surface of the calcined body to a thickness of 60 to 300 am. Next, this was heated at a temperature increase/decrease rate of 40 to 60°C/hr.
1000-1300°C preferably 1100-1250
Main firing is carried out at °C for 3 to 7 hours. A glass paste prepared by adding ethyl cellulose, butyl calpitol, n-butyl acetate, etc. as an organic binder to glass powder is applied to a thickness of 100 to 300 am on the above-mentioned insulating coating layer, and the temperature is raised and lowered in air at a rate of 100 to 300 am. 200'C/hr,
It is preferable to form the glass layer by heat treatment at 400 to 600°C for 0.5 to 2 hours.

After that, both end faces of the obtained voltage nonlinear resistor were bonded to SiC,
Al□03. Polishing is performed using water, preferably oil, as the polishing liquid with a polishing agent of #400 to #2000 such as diamond. Next, after polishing and cleaning the polished surfaces, metallicon electrodes made of, for example, aluminum metallicon are provided on the front surfaces of both polished end surfaces by, for example, thermal spraying to obtain a voltage nonlinear resistor.

Note that the average pore diameter in the metallicon electrode layer is 1 to 10 μm.
It is preferable to set it as the range of. The reason for this is to ensure the adhesion of the electrode formation surface of the resistor on which the metallicon electrode is disposed and the uniformity of the electrode layer.

Among these, when attaching the electrode, the metallicon electrode specified in the present invention can be obtained by variously changing the spraying conditions such as the pressure, temperature, and thickness of the metallicon when spraying the metallicon. Here, the manufacturing conditions are not particularly characteristic in the present invention, and as long as the resulting metallicon electrode of the voltage nonlinear resistor has the porosity and thickness specified in the present invention, it is the object of the present invention. A voltage nonlinear resistor is obtained.

Below, the results of measuring various characteristics of actual voltage nonlinear resistors within and outside the scope of the present invention will be described.

In the voltage nonlinear resistor with a diameter of 47 mm and a thickness of 20 mm created by the method described above, the porosity of the metallicon electrode (
%) and its thickness on various properties, samples Nα1 to Nα9 within the scope of the present invention and samples Nos. 1 to 4 outside the scope of the present invention were prepared, and the respective switching surge withstand capacities and ΔVlffiA was measured after the lightning surge was applied.

The results are shown in Table 1. However, the opening/closing surge resistance is 8
A device that is destroyed after repeatedly applying pulse currents of 00A, 100OA, and 1200A with a current waveform of 2 ms 20 times is marked with a ×, and an element that is not destroyed is marked with a mark of ◯. Also,
ΔVIIRA after lightning surge application indicates the rate of decrease in VlmA after applying a current of 40 kA 10 times with a current waveform of 4/10 us. Note that the average and standard deviation σ are for each sample 1
Calculated based on 0 measured values.

In addition, the porosity of the metallicon electrode was measured after polishing the sample.
After observing with EM and photographing, the pore area occupancy rate (pore area/metallicon area) was measured from the photograph using an image analysis device, and the porosity was determined.

Star-1-1 From the results in Table 1, Samples Nos. 1 to 9, which are voltage nonlinear resistors within the scope of the present invention, have improved switching surge resistance compared to Comparative Examples Nos. 1 to 4. It was also found from the average value of ΔVlffiA (%) after the lightning surge was applied that the drop in the variable voltage was reduced, and from the standard deviation it was found that the variation in the characteristics of individual samples was reduced. Preferably, the thickness of the metallicon is 50 to 200 μm. Further, the results of the surge resistance at 1000A in Table 1 are shown in FIG. 1, with the X-axis representing the metallicon thickness (μm) and the Y-axis representing the porosity (%). As can be seen from Figure 1, X is the metallicon thickness (μm) and Y is the porosity (%).
It can be seen that the required surge resistance can be obtained within a range that satisfies Y≦□X+7.

(Effects of the Invention) As is clear from the above detailed explanation, according to the voltage nonlinear resistor of the present invention, by defining the thickness and porosity of the metallicon electrode, there is little variation in electrical characteristics. A voltage nonlinear resistor with good surge resistance and charging life characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the thickness and porosity of the metallicon electrode of the voltage nonlinear resistor of the present invention. Patent applicant Nippon Insulator Co., Ltd.

Claims (1)

[Claims] 1. In a voltage nonlinear resistor in which a metallicon electrode is provided on a sintered body formed by molding and firing a mixture of metal oxides containing zinc oxide as a main component, the porosity of the metallicon electrode is such that Y is 1. A voltage nonlinear resistor, characterized in that Y≦1/10X+7, where X is a metallization thickness (μm).