JPH09148106A - Method of manufacturing voltage non-linear resistor - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a method capable of heating a voltage non-linear resistor having a zinc oxide content of 60 vol% or more in a short time. SOLUTION: In a voltage nonlinear resistor containing zinc oxide as a main component, in a process that requires heating in the manufacturing process,
The ceramic material is irradiated with microwaves having a resonance frequency of 2.45 GHz to raise the temperature by self-heating of the ceramic material.

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 non-linear resistor mainly containing zinc oxide and used for overvoltage protection.

[0002]

2. Description of the Related Art Voltage nonlinear resistors are widely used for surge protection of electronic circuits and surge protection of power equipment such as lightning arresters. A typical example thereof is one containing zinc oxide as a main component. There are many steps that require heating in the manufacturing process of voltage nonlinear resistors whose main component is zinc oxide, but most of them require an indirect heating method that raises the ambient temperature around the ceramic material by other heat sources. I am using.

[0003]

[Problems to be Solved by the Invention]
When a ceramic material is indirectly heated, the temperature of the ceramic material rises in a relatively short time for a ceramic material with a small capacity, but the ceramic material with a large capacity has a large heat capacity. Since it takes time to rise, it is difficult to improve production efficiency, and there is much waste in terms of energy. On the other hand, when the heat source is directly applied to the ceramic material, it is smaller than the above in terms of time and energy, but the temperature distribution varies and is not practical.

An object of the present invention is to provide a method of manufacturing a voltage non-linear resistor which can efficiently heat a ceramic material in a short time.

[0005]

Means for Solving the Problems In order to solve the above problems, the present invention relates to a voltage non-linear resistor having a zinc oxide content of 60 vol% or more, and a ceramic is used in a process that requires heating in its manufacturing process. Irradiate the material with microwaves,
It is characterized in that the temperature is raised by self-heating of the ceramic material.

According to the present invention, the energy efficiency is good and the temperature of the ceramic material can be raised in a short time.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention relates to a voltage non-linear resistor having a zinc oxide content of 60 vol% or more. It irradiates microwaves and raises the temperature by self-heating of the ceramic material.
Zinc oxide has a relatively large dielectric loss factor in the microwave band and self-heats when irradiated with microwaves, which can efficiently raise the temperature of the ceramic material in a short time.

According to the second aspect of the invention, the frequency of the microwave to be irradiated is set to 2.45 GHz, so that the microwave can be irradiated at a high output and the productivity can be improved.

Specific embodiments of the present invention will be described below. Zinc oxide, bismuth oxide, cobalt oxide,
Manganese oxide, chromium oxide, and silicon oxide were added to each of 0.
5 mol% was added, and antimony oxide was added so that the total amount added was 1.0 mol%, and water, an organic binder, a dispersant and the like were added thereto and then mixed.

Next, after granulating and molding these mixtures,
Fired at a temperature of 1150 ° C., diameter 33 mm, thickness 33
mm was obtained.

The above sample was heated by a hot air circulation dryer set to each target temperature, and the resonance frequency was 2.4.
Table 1 shows the results of confirming the difference in the arrival time of the ceramic material sintered body temperature to the target temperature from what was heated by irradiation with microwaves of 5 GHz and high-frequency output of 500 W.

[0012]

[Table 1]

As is clear from these results, the one using microwave can raise the temperature of the sintered body in a very short time. Further, FIG. 1 shows the results of confirming the cooling rate by raising the surface temperature of the sintered body to 300 ° C. by the above method and then leaving it at room temperature. From these results, it is found that the temperature distribution in the sintered body is similar to that of the case of using the dryer, because the cooling rate when heated using microwaves is almost the same as that of the case of using the dryer. .
Moreover, it has been confirmed that these behaviors have the same tendency even in the process before the ceramic material is sintered.

Next, the amount of zinc oxide in the object to be heated and the effect of microwave heating were examined. First, since the dielectric loss factor in the microwave body is small with respect to zinc oxide, silicon dioxide having a small effect of microwave heating is added at a rate of 0 to 100 vol%, and after granulating and molding, the temperature is 300 ° C. At 3
After dehydration for a period of time, a molded product having a diameter of 23.5 mm and a thickness of 30 mm was obtained.

Next, a resonance frequency of 2.45 was applied to the above sample.
FIG. 2 shows the result of heating by irradiating with microwaves of GHz and high frequency output of 500 W for 2 minutes.

From this result, the content of zinc oxide was 60v.
When it is ol% or less, the heating effect by microwaves is significantly reduced, so the content of zinc oxide is desirably 60% or more, preferably 80% or more.

Regarding the resonance frequency, it is possible to heat at frequencies other than 2.45 GHz, but it is difficult to use a frequency band other than this frequency at a high output due to legal problems, so it is outside the scope of the present invention. And

[0018]

According to the present invention, the temperature of the ceramic material can be raised in a short time with good energy efficiency, and the production efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a relationship between a temperature of a ceramics sintered body and cooling time when heating is performed using a conventional hot air circulation dryer and the microwave of the present invention and cooling is performed at room temperature.

FIG. 2 is a characteristic diagram showing the relationship between the content of zinc oxide in the object to be heated and the effect of microwave heating.

Claims (2)

[Claims] 1. In a voltage nonlinear resistor having a zinc oxide content of 60 vol% or more, a ceramic material is irradiated with microwaves in a process that requires heating in the manufacturing process,
A method of manufacturing a voltage non-linear resistor in which the temperature is raised by self-heating of a ceramic material. 2. The microwave irradiation frequency is 2.45.
The method of manufacturing a voltage non-linear resistor according to claim 1, wherein the voltage is GHz.