JPH0744087B2 - Non-linear resistor - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a non-linear resistor containing zinc oxide as a main component,
In particular, it relates to a non-linear resistor having an improved composition of a metallikon electrode.

[Technical background of the invention and its problems]

An overvoltage protection device is used to protect an electric system by removing an overvoltage superimposed on a normal voltage in the electric system.

For this overvoltage protection device, a non-linear resistor is used which has a substantially insulating characteristic at a normal voltage and has a relatively low resistance value when an overvoltage is applied.

The non-linear resistor can be made by mixing zinc oxide (ZnO) with a metal oxide and firing the formed element body.

ZnO-based non-linear resistors are superior to overvoltage protection devices that use SiC-based non-linear resistors because their non-linear characteristics are steep in a small current range and have a sharp rise until reaching a large current. Overvoltage protection device can be made.

However, ZnO-based non-linear resistors have many manufacturing processes, and many of them are industrially difficult to mass-produce, and the non-linear resistance characteristics are greatly deteriorated and the characteristics vary greatly. There is a problem in that other performance deterioration such as withstand capacity may occur. It is known that the discharge withstand capability is also affected by the electrode forming process means.

That is, a method for forming an electrode on a ZnO-based non-linear resistance element is to apply a silver paste to form a silver electrode.
There is a method known in JP-A-23515 and a metallikon method known in JP-B-59-45202 in which an electrode is formed by metal spraying. The metallikon method is particularly effective because it is easy to form and the discharge withstand capability can be improved.

However, even in the case of using this method, it is desired to further improve the adhesion between the element body and the electrode and the durability of the electrode.

[Object of the Invention]

The present invention has been made to solve the above-mentioned demand,
It is an object of the present invention to provide a non-linear resistor with improved discharge withstand capability and non-linear resistance characteristics.

[Outline of Invention]

According to the present invention to achieve the above object, in order to form a metallikon electrode having a stable adhesion strength, Mg, Ca, as a main content material, any one of 0.1 to 10 wt% of aluminum, or a main content Aluminum containing 0.1 to 12 wt% of at least two kinds of Mg, Ca, and Ti is used as the containing material to improve the adhesion between the element and the electrode and also improve the durability of the electrode. Is characterized by.

Example of Invention

Hereinafter, the present invention will be described based on examples. Zinc oxide (ZnO) powder, which is the main component, is added to bismuth oxide (Bi ₂ O ₃ ), antimony oxide (Sb ₂ O ₃ ), chromium oxide (Cr ₂ O ₃ ), cobalt oxide (CoO) and manganese oxide (MnO). Powders of metal oxides such as the above are added in the range of 0.01 to 6.0 mol% and mixed by a ball mill. At this time, the oxide and the organic binder are put into, for example, a spray dryer to form spherical aggregates. This powder mixture is pressed, for example, 100 mm diameter, 25 mm thickness
Mold into a disc.

This molded product is placed in an electric furnace and fired. The firing temperature is about 1250
At 6 ° C, a time of 6 hours is suitable.

The disc-shaped fired product after firing, that is, the nonlinear resistance element body shrinks more than before firing, but has a substantially uniform composition and density. Next, both flat surfaces of this element body are polished by about 0.1 to 2 mm. A metal mainly composed of aluminum is sprayed (metallikon) on the polished surface to form electrodes and complete the non-linear resistor.
Here, the metallikon was performed using the wire having the composition shown in Table 1.

In this case, the internal spraying pressure and the spraying distance under the metallikon conditions were the same, but the spraying voltage was raised and lowered according to the melting point of the composition.

The goggle test generally used as a means to examine the adhesion of the coating film of the paint to measure the adhesion strength of the metallikon electrode obtained in this way Make 100 pieces (10 pieces x 10 pieces),
When the cellophane tape was put on it and immediately peeled off, the number of eyes with the metallikon film peeled off is calculated. ) Shows the results measured in FIG. In nonlinear resistor of Matabetsu, the voltage V ₁₀ k _A when flowing 10k _A in a non-linear characteristic _{(V 12 k A / V 1} m A · 8 × 20μs waveform voltages V ₁ when the flow 1mA in DC The result of measuring the ratio of mA) is shown in FIG.

Next, Fig. 3 shows the results of measuring the discharge withstand capability (current value when the resistor breaks down by applying a square wave pulse of 2ma wavelength three times at 1-minute intervals) using another non-linear resistor. .

It can be seen from FIGS. 1, 2 and 3 that by adhering an appropriate amount of impurities to aluminum, the adhesion of the electrodes is improved and the non-linear characteristics and discharge withstand capability are improved. It is considered that this is because the interface resistance between the electrode surface and the element body surface becomes uniform, and when a large current is passed, a uniform current flows through the entire surface of the element body, so that the energy applied is borne by the entire cross section of the element.

As described above, when a material containing 0.1 to 10 wt% of Mg, Ca, and Ti added to aluminum is used as the material for the metallikon electrode, the adhesion of the electrode is improved, and a nonlinear resistor with improved nonlinear characteristics and discharge withstand capability is obtained. I can do things.

The above examples are examples in which Mg, Ca, and Ti were added independently, but a material in which the three elements were mixed in appropriate proportions in the range of 0.1 to 12 wt% and added to aluminum However, the same effect can be obtained. Further, it has been found that when the content exceeds the above-mentioned addition range, the adhesion of the electrode is poor and the discharge withstand capability is also poor.

(Effects of the Invention) As described above, according to the present invention, Mg, Ca, and Ti are 0.1% to 10% by weight as a main content material of the metallikon electrode provided in the non-linear resistor containing ZnO as a main component. In a range,
Alternatively, by combining two or more kinds of aluminum into aluminum containing 0.1 to 12 wt%, the adhesive strength with the non-linear resistance element can be improved, and the non-linear characteristic and the discharge withstand capability can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing the results of a cross stitch test in which the adhesion of electrodes of a non-linear resistor manufactured by using the manufacturing process of the present invention is measured, and FIGS. 2 and 3 show the non-linear resistor of the present invention. It is a curve figure explaining a nonlinear characteristic and discharge endurance characteristic.

Claims (2)

[Claims] 1. A non-linear resistance element comprising a non-linear resistance element formed by firing a metal oxide containing zinc oxide as a main component and a metallicon electrode provided on the non-linear resistance element. A non-linear resistor formed of aluminum containing 0.1 to 10 wt% of any one of Ti. 2. A non-linear resistance element comprising a non-linear resistance element formed by firing a metal oxide containing zinc oxide as a main component, and a metallikon electrode provided on the non-linear resistance element. Combine at least two kinds of Ti
A non-linear resistor formed of aluminum containing 0.1 to 12 wt%.