JPH07249505A - Manufacture of nonlinear resistor - Google Patents

Abstract

PURPOSE:To provide a nonlinear resistor manufacturing method by which a compact nonlinear resistor can be manufactured. CONSTITUTION:In a nonlinear resistor manufacturing method by which a nonlinear resistor is manufacture by molding and baking ZnO particles mixed at least with Bi2O3 and Sb2O3 particles, the particle sizes of the >=50wt.% ZnO and Bi2O3 particles are adjusted to <0.1mum and the particle sizes of the 50wt.% Sb2O3 particles are adjusted to >=0.5mum. with the maximum particle size being controlled to <=1mum.

Description

Detailed Description of the Invention

[0001]

The present invention comprises ZnO as a main component,
The present invention relates to a method for producing a voltage non-linear resistor formed by adding and mixing at least Bi ₂ O ₃ and Sb ₂ O ₃ , molding and firing.

[0002]

2. Description of the Related Art Voltage nonlinear resistors containing ZnO as a main component are widely used in surge arresters and surge absorbers for the purpose of voltage stabilization or surge absorption because of their excellent nonlinear voltage-current characteristics. This voltage nonlinear resistor is
An oxide such as Bi ₂ O ₃ or Sb ₂ O ₃ is added to ZnO which is the main component, and molding and firing are performed. Preferably, an inorganic substance for forming a lateral high resistance layer is applied and then fired again, and then the sintering is performed. It can be made by attaching electrodes to the body.

Among them, in order to obtain a voltage non-linear resistor having good electrical characteristics such as varistor voltage, voltage non-linear index, limiting voltage, etc. even by low-temperature firing, as additive and ZnO powder, 50 wt% or more of each is added. Particle size is 0.
1 μm or less, and 99% by weight or more of particles have a particle size of 0.1.
A technique using raw material powder having a size of 5 μm or less is disclosed in Japanese Patent Publication No.
No. 0-927.

[0004]

However, according to the technique disclosed in Japanese Patent Publication No. 60-927, not only ZnO but all other additives have a particle size of 50% by weight or more and a particle size of 0. Since it is used as a finely-divided raw material powder having a particle size of 1 μm or less and a particle size of 99% by weight or more of 0.5 μm or less, good electrical characteristics can be obtained, but densification is slow, There is a problem that a precise voltage nonlinear resistor cannot be obtained.

The object of the present invention is to solve the above problems,
An object of the present invention is to provide a method for manufacturing a voltage non-linear resistor that can obtain a more precise voltage non-linear resistor.

[0006]

A method of manufacturing a voltage non-linear resistor according to the present invention comprises ZnO as a main component and at least Bi.
₂ O ₃ and Sb ₂ O ₃ are added, mixed, molded and fired, and in a method for producing a voltage non-linear resistor, 50% by weight or more of each of ZnO and Bi ₂ O ₃ contained in the raw material powder is used. The particle diameter is 0.1 μm or less, and 50% by weight or more of Sb ₂ O ₃ has a particle diameter of 0.5 μm or more and a maximum diameter of 1 μm or less.

[0007]

In the above-mentioned structure, ZnO and Bi ₂ O ₃ among the ZnO and other additives in the raw material powder are refined as in the conventional case, while Sb ₂ O ₃ and preferably Sb ₂ O ₃ and Cr are added. Granulation is performed in the same manner as in the conventional method by using ₂ O ₃ as a raw material powder in which 50% by weight or more of the particles have a particle size of 0.5 μm or more and the maximum size is 1 μm or less, which are relatively large.
It has been found that a dense voltage nonlinear resistor can be obtained by molding and firing to obtain a voltage nonlinear resistor.

Where Sb ₂ O ₃ and preferably Sb
_The reason why a dense voltage non-linear resistor can be obtained by increasing the sizes of ₂ O ₃ and Cr ₂ O ₃ without making them fine is that densification and suppression of grain growth are contradictory in liquid phase sintering. Yes, grain growth is suppressed by suppressing mass transfer in the liquid phase. The grain growth inhibitor has the effect of slowing the mass transport at the interface during the dissolution-precipitation process during liquid phase sintering, and it is generally considered that if the grain growth rate decreases, the densification rate also decreases. Also, the smaller the particle size is, the more activated the densification is. ZnO varistor is Bi ₂ O
Liquid phase sintering in which _three phases generate a liquid phase and densify,
It is well known that Sb ₂ O ₃ and Cr ₂ O ₃ have a grain growth suppressing effect. Therefore, ZnO, Bi ₂
It is presumed that densification was promoted by making the O ₃ particles finer and making the particle sizes of the Sb ₂ O ₃ and Cr ₂ O ₃ particles larger to some extent.

[0009]

EXAMPLE A method of manufacturing a voltage non-linear resistor according to the present invention is as follows. First, a raw material powder consisting of zinc oxide as a main component and a predetermined amount of a subcomponent such as bismuth oxide, cobalt oxide, manganese oxide, for example, Bi ₂ O ₃ 1.0 mol%, Sb ₂ O ₃ 1.0 mol%,
Cr ₂ O ₃ 0.5 mol%, MnO ₂ 0.5 mol%, CoO 1.0 m
ol%, SiO ₂ 1.5 mol%, NiO 1.0 mol%, Al ₂ O
₃ Prepare a raw material powder consisting of 0.005 mol% and the balance ZnO.

What is important here is that ZnO and Bi ₂ O ₃ are added to 50% of ZnO and other additives, respectively.
The particle size of the particles of not less than wt% is adjusted to 0.1 μm or less, and Sb ₂ O ₃ and preferably Sb ₂ O ₃ and Cr are used.
50% by weight or more of ₂ O ₃ has a particle diameter of 0.5.
It is necessary to adjust the maximum diameter to 1 μm or less for μm or more.
Regarding the raw materials other than the raw materials specified here, the particle distribution is not particularly limited, and finely divided particles can be used as in the conventional case.

Next, the prepared raw material powders are wet-mixed with a ball mill or the like, dried, granulated, and molded into a predetermined shape, and the obtained molded body is degreased to remove the binder. afterwards,
The obtained degreased body is fired according to a predetermined firing schedule while pressurizing the degreased body, preferably with a heating device that also serves as a pressurizing device, to obtain a sintered body. Again, both ends of the sintered body are preferably polished, and electrodes are formed by a method such as aluminum metallikon spraying or silver baking to obtain a voltage non-linear resistor having, for example, a diameter of 47 mm, an electrode diameter of 46 mm, and a thickness of 20 mm. There is.

An actual example will be described below.Example 1 First, obtain the typical reagents that make up the voltage nonlinear resistor.
However, according to the mixing ratios A to C shown in Table 1 below,
As described in Table 2 below, ZnO and Bi₂ O ₃ , Sb
₂ O₃ And adjust the particle size of other raw materials, adjust the particle size
Sample No. Raw material powders 1 to 9 were obtained. Then got
200 kg / cm for each raw material powder² Preformed with pressure
Temperature rising rate: 200 ° C / hr, holding at 1200 ° C for 1 hour,
Cooling rate: 200 kg / cm² Firing on the schedule
went. For firing, use atmospheric pressure firing in an air atmosphere and pressurizing mechanism.
Pressure baking was performed using a heating device that also had the function. Finally got
Bulk density measurement by buoyancy method for each fired body
I went. The results are also shown in Table 2.

[0013]

[Table 1]

[0014]

[Table 2]

From the results of Table 2, ZnO and Bi ₂ O ₃
Sample N having a particle size of 50% by weight or more and a maximum particle size of 1 μm or less and a particle size of Sb ₂ O ₃ of 50% by weight or more and a maximum particle size of 1 μm or less
o. It can be seen that Nos. 4 to 6 have the highest bulk density irrespective of the particle size of the other raw materials regardless of normal pressure firing or pressure firing. Further, comparing normal pressure firing and pressure firing, in any case, pressure firing can obtain a higher bulk density.

Example 2 In order to examine the influence of the particle size distribution of Cr ₂ O ₃ contained in other raw materials, the sample No. 1 of Example 1 was examined. 5, the particle size of Cr ₂ O ₃ was changed according to ABC of Table 1 as shown in Table 3 below, and Sample N was prepared according to the same manufacturing method as in Example 1.
o. The fired bodies of 11 to 13 were obtained, and the bulk density was measured in the same manner as in Example 1. The results are shown in Table 3.

[0017]

[Table 3]

From the results shown in Table 3, among the examples of the present invention, Sample No. 1 in which the particle size of Cr ₂ O ₃ was 50% by weight or more, the particle size was 0.5 μm or more, and the maximum size was 1 μm or less.
It was found that No. 12 can obtain a good bulk density regardless of whether the firing is normal pressure or pressure firing.

[0019]

As is apparent from the above description, according to the present invention, among ZnO and other additives in the raw material powder,
ZnO and Bi ₂ O ₃ become finer as in the conventional case, while Sb ₂ O ₃ and preferably Sb ₂ O ₃ and Cr ₂ O.
_{Using 3} as a raw material powder, 50% by weight or more of which has a particle size of 0.5 μm or more and a maximum size of 1 μm or less, is used to granulate, shape, and fire in the same manner as in the past, and voltage non-linearity is used. If a resistor is obtained, a precise voltage nonlinear resistor can be obtained.

Claims (3)

[Claims] 1. ZnO as a main component and at least Bi ₂ O
_{In the} method of manufacturing a voltage nonlinear resistor obtained by adding, mixing, and sintering ₃ , Sb ₂ O ₃ , 50% by weight or more of each of ZnO and Bi ₂ O ₃ in the raw material powder used, Is 0.1 μm or less and 5 of Sb ₂ O ₃
A method for producing a voltage non-linear resistor, characterized in that 0% by weight or more of particles have a particle diameter of 0.5 μm or more and a maximum diameter of 1 μm or less. 2. The raw material powder, wherein 50% by weight or more of particles have a particle diameter of 0.5 μm or more and a maximum diameter of 1 μm or less.
The method for producing a voltage non-linear resistor according to claim 1, wherein r ₂ O ₃ is further added. 3. The method for producing a voltage non-linear resistor according to claim 1, wherein firing is performed while applying pressure by a heating device that also serves as a pressurizing device.