JPS6035803B2 - Manufacturing method of non-linear resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method for manufacturing a metal oxide nonlinear resistor containing zinc oxide or zinc oxide and magnesium oxide as main components, in which mixing steps and This invention relates to a method for manufacturing a nonlinear resistor with an improved pulverization process.

The mixing or pulverizing equipment used in the manufacturing process of ceramic products is mainly a ball mill. The particle size distribution is not as sharp and the dispersibility is not good. When a conventional ball mill is used under standard conditions in the mixing step or pulverization step during the manufacturing process of a metal oxide nonlinear resistor whose main components are zinc oxide or zinc oxide and magnesium oxide, ■ processing time becomes longer.

(2) Since media for mixing and grinding are required to have a certain level of mass and specific gravity, the media cannot be made too small and effective mixing and dispersion and grinding and dispersion cannot be performed. ■
Since pulverization is performed by the impact force of the falling media, contamination by the media often occurs. ■A sharp particle size distribution cannot be obtained. ■Unable to process highly viscous slurry. It had drawbacks such as. In addition, if a vibration mill is used instead of a ball mill, the processing time will be shorter, but under the conditions that create the ideal pole movement for a vibration mill, the energy generated within the mill will be too large. However, the process has disadvantages such as contamination of the object to be processed and increased wear inside the mill. The above-mentioned drawbacks of ball mills and vibration mills cause reductions in current-voltage characteristics (hereinafter abbreviated as V-1 characteristics) and discharge withstand capacity of nonlinear resistors. This invention was made in order to eliminate the above-mentioned drawbacks, and the processing time is short, the object to be processed is not contaminated, and effective mixing and pulverization and dispersion can be carried out using 4-millimeters and media. A sharp particle size distribution can be obtained, and even highly viscous slurry can be processed. This allows the sharp particle size distribution and homogeneous dispersion to be managed and controlled under specified conditions, resulting in excellent V-1 characteristics and excellent discharge durability. The present invention provides a method for manufacturing a non-linear resistor, which makes it possible to obtain a non-linear resistor having a small variation.

Next, as a representative example of the present invention, the entire composition of a zinc oxide non-linear resistor will be explained, in which the pulverization process of the calcined raw material in the manufacturing method of a metal oxide non-linear resistor whose main components are zinc oxide and magnesium oxide is explained. Mix the ingredients in a designated device, and
The powder and granules calcined at oo~1100q○ have an average particle size (5
0% weight cumulative particle size) is 1.0 to 3.0 microns, the particle size is more than half the average particle size and less than twice the average particle size, and the particle size is about 70% or more by weight Wet-pulverize and disperse to achieve particle size distribution.

In this case, it is sufficient that particles having a particle size of 1/4 or more and 4 times or less of the average particle size account for 65% or more by weight.

An effective mechanism for fine pulverization at this time is a method in which a large number of balls with a fairly small diameter are used as the pulverizing media and are forced into a wet state together with the raw material. The slurry of the raw material, which has been pulverized and dispersed in accordance with the controlled conditions, is then spray-dried, shaped and fired.
The sintered body produced in this manner is appropriately post-treated to complete the device. The figure shows the difference in the average particle diameter and particle size distribution of the processed material between the method of the present invention that effectively utilizes the difference in the grinding mechanism and the method that uses a conventional ball mill.

A is a case according to the present invention, and b is a case according to a conventional method. or,
Table 1 shows a comparison of various properties between cases where the particle size and particle size distribution were controlled as described above and cases where they were not. Table 1 Note: The V-1 characteristic (Q) of the element is expressed by the following formula.

・: (ki) Q 1 Current V: Voltage C: Constant Q: Indicator Line Index As is clear from Table 1, by regulating the particle size and particle size distribution in the pulverization process and increasing the dispersion effect, It can be seen that the homogeneity of the body was increased and the V-1 characteristics and discharge withstand capacity were greatly improved.

Furthermore, despite these great effects, the pulse resistance is excellent, and the resistance leakage current is extremely small, so that the excellent characteristics of the prior art are not impaired at all. The homogeneity of the composite and extremely low contamination mean that the V of this non-linear resistor is
It is considered that this contributes greatly to the improvement of -1 characteristics and discharge withstand capacity. In particular, it is believed that the more homogeneous pulverization and dispersion of the sintered body ensures that the sintering reaction progresses in a necessary and sufficient manner and that the fine structure of the sintered body becomes homogeneous. Next, another example will be shown.

The average particle size is 1.0 to 30 for mixed grinding of unprepared ingredients.
A case will be described in which a sharp particle size distribution and homogeneous dispersion are defined such that the particle size in microns is between one-half and twice the average particle size and approximately 70% by weight.

Bismuth oxide (Bi203), antimony oxide (SQ0
3), cobalt oxide (Coo), manganese oxide (Mn0
), chromium oxide (Cr203), etc., weighed to have a predetermined composition ratio, are mixed and pulverized at once, and the average particle size is 1.0 to 3.0 microns, and the particle size is 2 times the average particle size. Wet mixing and pulverization is performed to obtain a sharp particle size distribution in which approximately 70% by weight is contained in 1/2 or less.

As a mechanism for mixing and pulverizing at this time, it is effective to use a method in which a large number of balls with a fairly small diameter are forced into a female frame together with the raw material in a wet manner as the pulverizing media. The slurry of mixed and pulverized raw materials and the main components, zinc oxide and magnesium oxide, are mixed again to meet the controlled conditions, dried, and then the device is completed through the prescribed manufacturing process. . Table 2 shows a comparison of various properties between cases where only the characteristic components are mixed and pulverized and the average particle size and particle size distribution are controlled to predetermined conditions and cases where this is not the case.

Table 2 Note Regarding Q, ・=(ki〉Q I: Current V: Voltage C: Constant Q: Linear index In addition, in the above-mentioned present invention, if the average particle size of the powder or granule is to be 0.1 micron or less, pulverization This requires a long time and may therefore enter the raw material as impurities due to wear of the grinding media.

Further, if the diameter is larger than 3 microns, sufficient homogeneity cannot be obtained, which may lead to a decrease in discharge durability. Furthermore, the powder size was set to be more than 1/4 times the average particle size and less than 4 times the average particle size, accounting for 63 cents or more in terms of weight ratio. cannot be obtained, which causes a decrease in discharge withstand capacity. As explained above, this invention sharpens the particle size distribution of powder and performs homogeneous dispersion in the mixing step and pulverization step in the manufacturing method of a metal oxide nonlinear resistor, thereby producing a homogeneous sintered body. It has been found that the present invention can provide a nonlinear resistor element with excellent energy withstand capacity, and can greatly improve the performance of gapless lightning arresters, which have been attracting attention recently.

[Brief explanation of drawings]

The figure is a diagram illustrating the average particle size and particle size distribution of objects to be treated according to the method of the present invention and the conventional method.

Claims (1)

[Claims] 1. In a method for manufacturing a metal oxide nonlinear resistor containing zinc oxide or zinc oxide and magnesium oxide as main components, The average particle size (50% weight cumulative particle size) of the powder or granular material is 0.1 to 3.0 microns, and the particle size is 1/4 or more and 4 times or less of the average particle size in terms of weight ratio. A method for manufacturing a non-linear resistor, characterized in that the particle size distribution of the powder is sharpened so that it accounts for 65% or more, and the powder is homogeneously dispersed. 2. The method for manufacturing a nonlinear resistor according to claim 1, wherein the mixing step and the pulverizing step are performed wet.