JPH01228105A - Manufacture of non-linear voltage resistance - Google Patents

Abstract

PURPOSE:To reduce the variation in characteristics against a number of lightning surge applications by a method wherein the mixture for insulated layer, consisting of a silicon compound, a zinc compound, a bismuth compound and an antimonial compound for the remaining part, is coated on the side face of a resistor base. CONSTITUTION:The composition of a resistor element, especially the content of silicon oxide is specifically prescribed at 1-4mol% by converting it into SiO2, the composition of the mixture for the insulating coated layer on the side face of the resistor base is set at 50-80mol% by converting the content of silicon compound into SiO2, the content of zinc compound is set at 10-40mol% by converting it into ZnO, the content of bismuth compound is set at 1-5mol% by converting it into Bi2O3, and the remaining part of antimonial compound is specified. Also, the varister voltage of the sintered non-linear voltage resistor is specified at 230-300V per unit length. Accordingly, the adhesion strength of the resistor element and the insulating coated layer at a low temperature can be increased by their synergistic effect, the surface discharge on the side face of the element when lightning surge is impressed, varistor voltage can be maintained high, and a limit voltage ratio can be reduced. As a result, the element having stabilized characteristics even for a number of lightning surge applications can be obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a voltage non-linear resistor containing zinc oxide as a main component, and in particular aims at improving the electrical characteristics of the voltage non-linear resistor. It is something to wax.

(Prior art) Voltage nonlinear resistors, which are usually insulators and have the property of acting as conductors when an excessive current flows, and are used in voltage stabilizing elements, shock absorbers, arresters, etc., are used for example in certain places. Quantitative amounts of bismuth oxide, cobalt oxide, manganese oxide,
It is manufactured through a process in which a raw material mixture containing antimony oxide, chromium oxide, nickel oxide, etc., with the remainder being zinc oxide, is pressure-formed and fired according to preset processing conditions, and electrodes are attached to the resulting sintered body. The varistor voltage (Vl-a) of the sintered body was approximately 180 to 200 V/mm.

As a prior document related to this, for example, Japanese Patent Application Laid-Open No. 62-237
Reference is made to Publication No. 703.

(Problems to be Solved by the Invention) The technology disclosed in the above publication adjusts the content of SiO□ in the components constituting the voltage nonlinear resistor to a range of 1.0 to 3.0 mol%. However, attempts are being made to improve the characteristics of the voltage nonlinear resistor by providing a high resistance layer of B1-3i-5b type oxide.

By the way, the above technology is aimed at manufacturing a voltage non-linear resistor that has strong adhesion between the voltage non-linear resistor element and the insulating coating layer and has excellent lightning surge withstand characteristics. As devices such as arresters that incorporate voltage non-linear resistors are becoming smaller, the varistor has a higher voltage (V, There has been a desire for a voltage nonlinear resistor whose characteristics change little when lightning surges are applied.

The purpose of this invention is to have a small limiting voltage ratio of 230 to 30
The purpose of the present invention is to propose a new method for manufacturing a voltage nonlinear resistor that has a high varistor voltage of 0 V/ma+ and whose characteristics such as varistor voltage change little even when lightning surges are applied many times.

Here, the varistor voltage (Vl-A) is DCIm applied to the resistor.
It means the applied voltage necessary to cause A to flow, and it is necessary to increase the varistor voltage in order to reduce the thickness of the element. Also, the limiting voltage ratio is a constant current (generally 10 to 40 kA) in the resistor.
) is the ratio of the applied voltage required to flow the varistor voltage, and the smaller the limiting voltage ratio, the better the equipment's protection performance against lightning surges.

(Means for solving the problem) This invention converts bismuth oxide into Bi2O2.
~2 mol%, 0.0% in terms of cobalt oxide as Co2O3.
1 to 2 mol%, 0.0% when manganese oxide is converted to Mn0z.
1 to 2 mol%, antimony oxide 0.1 to 2 mol% in terms of 5bz03, chromium oxide 0.1 to 2 mol% in terms of Cr2O2, nickel oxide 0 in terms of NiO
．． 1 to 2 mol%, aluminum oxide converted to ALO3 0.001 to 0.05 mol%, boron oxide 820
0.005 to 0.1 mol% in terms of 3, 8 g of silver oxide
A side surface of a voltage nonlinear resistor element body containing 0.001 to 0.05 mol% in terms of zO and 1.0 to 4.0 mol% in terms of silicon oxide as SiO□, with the remainder being zinc oxide. The silicon compound is 50 to 80 mol% in terms of SiO2.
, a mixture for an insulating coating layer consisting of 10 to 40 mol % of a zinc compound in terms of ZnO, 1 to 5 mol % of a bismuth compound in terms of Bi2O3, and the balance antimony compound is coated and then fired. In the solid body, the varistor voltage (Vl-A) is 230 to 230 per unit thickness (shell) of the sintered unit.
This is a method for manufacturing a voltage nonlinear resistor characterized in that the voltage is 300V.

(Function) In the above configuration, the composition of the voltage nonlinear resistor element, especially the content of silicon oxide, is specified as 1 to 4 mol% in terms of Sin, and the vA edge coating layer mixture on the side surface is In particular, the composition
The content of silicon compounds is converted to Sin and is 50 to 80.
Mol%, content of zinc compound converted to ZnO is 10~
40 mol%, bismuth compound converted to old 203 1~
5 mol%, the balance is identified as an antimony compound,
By specifying the varistor voltage of the fired voltage nonlinear resistor to be 230 to 300 V per unit length, the synergistic effect increases the adhesion strength between the voltage nonlinear resistor element and the insulating coating layer at lower temperatures than usual. This prevents creeping discharge on the side of the element when lightning surges are applied due to incomplete adhesion of the insulation coating layer, and the varistor voltage is high and the limiting voltage ratio is small, making the characteristics stable even when lightning surges are applied multiple times. It is possible to provide a device with

The reason for limiting the content of each component in the voltage nonlinear resistor element is as follows.

Big (h has the effect of forming a microstructure between ZnO particles as a grain boundary layer and promoting the grain growth of ZnO particles. If the amount added is less than 0.3 mol%, the grain boundary phase will not be sufficiently formed, The height of the electrical barrier formed by this grain boundary phase decreases, increasing leakage current and worsening nonlinearity in the low current range.On the other hand, if the amount added exceeds 2 mol%, the grain boundary phase becomes too thick, and grain growth of ZnO particles is promoted, deteriorating the limiting voltage ratio.For this reason, the amount of BizOs added is limited to 0.3 to 2 mol%, preferably 0.5 to 1.
2 mol% is good.

Co2O3 and MnO□ have the effect of increasing the height of the electrical barrier by partially dissolving in the ZnO particles and precipitating in the grain boundary phase. If both of these contents are less than 0.1 mol%, the height of the electrical barrier will decrease and nonlinearity in the low current range will worsen.

On the other hand, if the amount of Co, O3, and MnO□ added exceeds 2 mol %, the grain boundary phase becomes too thick and the limiting voltage ratio deteriorates. Therefore, the amounts of both Co2O3 and MnO added were limited to 0.1 to 2 mol%. Preferably Co□030
．． 5 to 1.5 mol%, Mn0z 0.3 to 0.7 mol%
Good.

sb! o3. Crz03 and NiO have the effect of suppressing abnormal grain growth of ZnO particles and improving the uniformity of the fired body by reacting with ZnO to form a spinel layer. If the amount added is less than 0.1 mol %, abnormal grain growth of ZnO particles occurs, resulting in non-uniform current distribution in the fired body. On the other hand, if it exceeds 2 mol %, the insulating spinel phase will be too large and the current distribution in the fired product will become non-uniform. Therefore, 5)) each of z03+ Cr2O3 and NiO was limited to 001 to 2 mol%. Preferably 5bzO,0
, 8 to 1.2 mol %, CrzOa O, 3 to 0.7 mol %, and Ni 0.8 to 1.2 mol %.

A E zOs forms a solid solution in ZnO and has the effect of lowering the resistance of an element made of ZnO. The amount added is o, ooi
If it is less than mol %, the resistance of the element cannot be sufficiently reduced and the limiting voltage ratio deteriorates. On the other hand, if it exceeds 0.05 mol %, the height of the electrical barrier decreases and nonlinearity in the low current range deteriorates. For this reason, it was limited to 0.001 to 0.05 mol%. Preferably it is 0.002 to 0.005 mol%.

B2O3 precipitates in the grain boundary phase together with Bi2O3 and SiO□ to promote grain growth of ZnO particles, and has the effect of vitrifying and stabilizing the grain boundary phase. If the amount added is less than o, oos mol%, the effect of stabilizing the grain boundary phase will be insufficient. By the way, if it exceeds 0.1 mol %, the grain boundary phase becomes too thick and the limiting voltage ratio deteriorates. For this reason, B20. The amount of addition was limited to o, oos to 0.1 mol%. Preferably it is 0.01 to 0.08 mol%.

Ag,0 has the effect of stabilizing the grain boundary phase by precipitating in the grain boundary phase and suppressing ion movement caused by electric charge, but if the amount added is less than 0.001 mol%, the grain boundary phase will be stabilized. The stabilizing effect is insufficient. On the other hand, if it exceeds 0.05 mol %, the grain boundary phase becomes unstable and the limiting voltage ratio deteriorates. Therefore, the amount of Ag, 0 added was limited to 0.001 to 0.05 mol%. Preferably it is 0.005 to 0.03 mol%.

Sing precipitates in the grain boundary phase together with BizOs and forms ZnO
It has the effect of suppressing particle growth and improving varistor voltage (V, MA). If the amount added is less than 1 mol%, Zn
The effect of suppressing grain growth of O particles is insufficient, making it impossible to increase the varistor voltage, and furthermore, the charging life deteriorates and the limiting voltage ratio increases. On the other hand, if it exceeds 4.0 mol %, the grain boundary phase becomes too thick, deteriorating the lightning surge resistance characteristics and lowering the varistor voltage after the lightning surge is applied. For this reason,
The amount of SiO2 added was limited to 1 to 4 mol%. Preferably it is 1.5 to 2 mol%.

The varistor voltage of the voltage nonlinear resistor can be adjusted to 230 to 3 by controlling the firing conditions, such as lowering the firing temperature.
00 V/nym. This is because when the varistor voltage is less than 230 V/nm or more than 300 V/mm, the limiting voltage ratio increases, the energy withstand capacity against lightning surge application decreases, and the rate of decrease in varistor voltage against lightning surge application also increases. It is from. In particular, the varistor voltage is preferably 240 to 280 V/mm.

Here, the energy withstand capacity is a means of relatively evaluating the withstand capacity of resistors with different varistor voltages, and the lightning surge withstand capacity is expressed as an energy value (current x voltage x application time). When the lightning surge withstand capacity is evaluated by the lightning surge current value, the element with a high varistor voltage has a high applied voltage, so the withstand capacity value shows a low value. Therefore, a fair evaluation cannot be made.

Next, in the composition of the mixture for the insulating coating layer to be applied to the side surface of the voltage ratio linear resistor element, the amount of silicon compound added is
O□ is set to 50 mol% or more and 80 mol% or less because
If the amount added is less than 50 mol%, the insulating coating layer will peel off and the lightning surge resistance characteristics cannot be improved, while if it exceeds 80 mol%, the 8i coating layer will exhibit hygroscopicity and the lightning surge resistance characteristics will fail. Since the properties were not improved, the amount of silicon compound added was limited to 50 to 80 mol% as SiO1. In addition, preferably it is 50-70 mol%.

If the amount of the zinc compound added is less than 10 mol% as ZnO, the insulating coating layer will exhibit hygroscopicity and the lightning surge resistance will not improve, while if it exceeds 40 mol%, the insulating coating layer will easily peel off. Therefore, the amount of zinc compound added is
The content was limited to 10 to 40 mol%. Preferably 20~
30 mol% is good. As will be described later, the zinc compound is thought to have a great effect on improving the adhesion between the element body and the insulating coating layer at low temperatures.

When the bismuth compound is added in an amount less than 1 mol % as Bi, 03, the insulating coating layer tends to peel off, while when it exceeds 5 mol %, the lightning surge resistance decreases. Therefore, the amount of bismuth compound added was limited to 1 to 5 mol% as BigOl. Further, since spinel (Zntz3Sbzz:+On) is also necessary in the insulating coating layer after firing in order to improve lightning surge resistance, the remainder was made of an antimony compound.

The thickness of the above insulating coating layer after firing is 30 μm.
If the thickness is less than 100 μm, the effect of improving lightning surge resistance will be extremely small, while if the thickness exceeds 100 μm, the adhesion will be incomplete and peeling will occur easily. Therefore, the thickness of the insulation coating layer after firing is 30
It is preferable to set it as 100 micrometers.

Here, as the composition of the mixture for the insulating coating layer, a silicon compound,
Although zinc compounds, bismuth compounds, and antimony compounds are specified, each compound must be heated at 1000°C or less (preferably 8°C or less).
Any material may be used as long as it changes to an oxide at temperatures below 00"C).

Specific examples include carbonates, nitrates, hydroxides, etc., but oxides are most preferred.

As mentioned above, the silicic acid compound, zinc compound, bismuth compound, and antimony compound in the insulation coating mixture applied to the side surface of the resistor element play an important role in improving the lightning surge resistance of the element. It can be thought of as follows.

When an insulating coating mixture consisting of a silicate compound, a zinc compound, a bismuth compound, and an antimony compound is applied to the element body and fired, each compound first changes into an oxide. Next, a reaction between silicon oxide and antimony oxide in the insulating coating mixture and zinc oxide in the material proceeds at the interface between the element body and the insulating coating mixture to form an insulating coating layer. This insulating coating layer is mainly composed of zinc silicate (zn
2sio4), zinc oxide, and antimony oxide (Zny/+Sbt/30*), and is formed at the part where zinc silicate contacts the element body.

Bismuth oxide in the insulating coating mixture functions as a flux to facilitate the above reaction. In this invention, since zinc oxide is also contained in the mixture for insulation coating, the reaction of producing zinc silicate and spinel proceeds also in the mixture for insulation coating. Therefore, in the present invention, even when the firing temperature is lowered in order to increase the varistor voltage, there is no deterioration in hygroscopicity, and a strong insulating coating layer with good adhesion to the element body is formed.

Although a silicon compound, a zinc compound, a bismuth compound, and an antimony compound are specified as the composition of the mixture for the insulating coating layer, each compound must be kept at a temperature of 1200°C or less (preferably 100°C or less).
Any material may be used as long as it changes to an oxide at temperatures below 00°C.

Specific examples include carbonates, nitrates, hydroxides, etc., but oxides are most preferred.

Next, specific manufacturing procedures for manufacturing a voltage nonlinear resistor by applying the present invention will be described.

Mix the main raw material of zinc oxide adjusted to a specified particle size with additives such as bismuth oxide, cobalt oxide, manganese oxide, antimony oxide, chromium oxide, silicon oxide, nickel oxide, silver oxide, boron oxide, etc. adjusted to a specified particle size. do. Silver nitrate or boric acid may be used instead of silver oxide or boron oxide. Preferably, bismuth borosilicate glass containing silver is used.

Next, a predetermined amount of an aqueous polyvinyl alcohol solution and a predetermined amount of an aluminum nitrate solution as an aluminum oxide source are added to these raw material powders.

This mixing operation preferably uses an emulsifying machine.

Next, deaeration is performed under reduced pressure, preferably at a vacuum level of 200 mmHg or less, to obtain a mixed slurry. Here, the water content of the mixed slurry is 3
0 to 35-t%, and the viscosity of the mixed slurry is 10
It is preferable to set it to 0 cp±50.

Next, the obtained mixed slurry is fed to a spray drying device so that the average particle size is 50 to 150 μm, preferably 80 to 120 μm.
Moisture content is 0.5-2. Owt%, more preferably 0.9
-1.5 wt% granulated powder is granulated.

Next, the obtained granulated powder was subjected to a molding process at a molding pressure of 8
00 to 1000 kg/cm" and molded into a predetermined shape.Then, the formed body is heated and cooled at a temperature raising/cooling rate of 50 to 70°C/h.
Preliminary firing is carried out under the conditions of 800 to 1 OOO'' C1 holding time of 1 to 5 hours at r. It is preferable to remove the binder by scattering over time.

Next, an insulating coating layer is formed on the side surface of the calcined body. In this invention, a bismuth compound, an antimony compound,
An oxide paste prepared by adding ethyl cellulose, butyl calpitol, n-butyl acetate, etc. as an organic binder to predetermined amounts of zinc compounds and silicon compounds such as bismuth oxide, antimony oxide, zinc oxide, and silicon oxide,
Coat the side surface of the calcined body to a thickness of 0 to 300 μm. Next, the temperature was raised and lowered at a rate of 30 to 60'C/hr, 1000
~1250'C preferably 2 at 1000-1200''C
Main firing is performed for ~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 μm on the insulating coating layer, and the temperature is raised and lowered in air at a rate of 100 to 200 μm. °C/
It is preferable to form the glass layer by heat treatment under the conditions of 400 to 600° C.2 holding time of 0.5 to 4 hours.

Finally, both end faces of the voltage nonlinear resistor are polished smooth, and aluminum electrodes are provided by thermal spraying.

(Example) Diameter 47 mm, thickness 2 with the component composition shown in Table-1
A zero-valent voltage nonlinear resistor was manufactured in the manner described above, and the varistor voltage (Vl-A), limiting current ratio, energy withstand capacity, rate of decrease in varistor voltage after lightning surge application, and insulation coating of each element obtained were The hygroscopicity of the layer was investigated. The results are also shown in Table-1.

In addition, the limiting current ratio is 10kA with a current waveform of 8720μs.
The energy withstand capacity was determined from the ratio of the applied voltage required to flow the current and the varistor voltage, and the withstand capacity (cleared twice) against the shock current of the current waveform of 4/lOμS was converted into an energy value. In addition, the rate of decrease in varistor voltage after a lightning surge is applied is the rate of decrease in varistor voltage after 10 repeated applications of a 30 KA current with a current waveform of 4710 μs. 2 at a pressure of 200 kg/cm2 in the liquid.
After being immersed for 4 hours, the moisture absorption state was inspected, and those with no bleeding in the insulating coating layer were marked as ○, and those with bleeding were marked as ×.

As is clear from Table 1, it was confirmed that the voltage nonlinear resistors (Nos. 1 to 26) conforming to the present invention were able to obtain satisfactory results for all of the investigated items.

Also, good results were confirmed regarding the charging life characteristics and switching surge resistance characteristics.

(Effects of the Invention) According to the present invention, the electrical characteristics are good, especially the varistor voltage is higher than that of conventional elements, the limiting voltage ratio is small, and the characteristics change little when lightning surges are applied many times. It is possible to obtain a voltage non-linear resistor that is advantageous for.

Patent Applicant Nippon Insulators Co., Ltd. Procedural Amendment Letter February 28, 1989 Director General of the Japan Patent Office Yoshi 1) Takeshi Moon 1, Indication of the case 1988 Patent Application No. 53677 2, Title of the invention 3, Amendment Relationship with the case of patent applicant 4, agent 1, “sintered unit thickness” on page 5, line 16 of the specification [
The unit thickness of the sintered body is corrected.

2. "Silicate compound" on page 13, lines 3 and 7
Correct each to "silicon compound".

3. Delete the space between lines 6 to 11 on page 14.

Claims (1)

[Claims] 1. Bismuth oxide converted to Bi_2O_3 is 0.3~
2 mol%, cobalt oxide 0.1 to 2 mol% in terms of Co_2O_3, manganese oxide 0.1 to 2 mol% in terms of MnO_2
, 0.1 to 2 when antimony oxide is converted to Sb_2O_3
Mol%, chromium oxide 0.1 to 2 mol% in terms of Cr_2O_3, nickel oxide 0.1 to 2 mol% in terms of NiO, aluminum oxide 0.00 in terms of Al_2O_3
1 to 0.05 mol%, 0.005 to 0.00 in terms of boron oxide as B_2O_3.
1 mol%, 0.001 to 0.05 mol% in terms of silver oxide as Ag_2O and 1.0 to 0.05 mol% as silicon oxide in terms of SiO_2
4.0 mol%, the balance being zinc oxide, on the side surface of the voltage nonlinear resistor element body, the silicon compound is 50 to 80 mol% in terms of SiO_2, and the zinc compound is 1 in terms of ZnO.
A mixture for an insulating coating layer consisting of 0 to 40 mol% of bismuth compound, 1 to 5 mol% of bismuth compound converted to Bi_2O_3, and the balance antimony compound is coated and then fired to produce a sintered body with a varistor voltage (V_l_m_A). A method for manufacturing a voltage nonlinear resistor, characterized in that the voltage is 230 to 300 V per unit thickness (mm) of the sintered body.