JPH0734402B2 - Voltage nonlinear resistor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage nonlinear resistor used in an overvoltage protection device.

[0002]

2. Description of the Related Art Conventionally, zinc oxide (ZnO) has been the main component.
It is widely known that a resistor containing a small amount of a metal oxide such as Bi ₂ O ₃ , Sb ₂ O ₃ , SiO ₂ , Co ₂ O ₃ and MnO ₂ as an auxiliary component exhibits excellent voltage nonlinearity. It is used for lightning arresters, etc., due to its nature.

As such a voltage non-linear resistor used in electric power equipment, for example, one having the composition disclosed in JP-A-63-136603 is suitable. But,
Even if these compositions are adopted, there still remains a drawback that the change rate ΔV _1mA of the varistor voltage V _1mA after application of a lightning surge is large.

Therefore, when designing the lightning arrester, it has been necessary to design in advance in consideration of the rate of change of V _1mA . On the other hand, as a method of suppressing the deterioration itself due to surge, a method of performing heat treatment at a temperature of 600 ° C or higher after firing the voltage nonlinear resistor is known. According to this method, the varistor voltage of the voltage nonlinear resistor is reduced. There is a drawback that the voltage is lowered and the limiting voltage ratio V _40KA / V _1mA is increased.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a voltage non-linearity which has a small rate of change in varistor voltage ΔV _1mA after application of a surge, a limited voltage ratio V _40KA / V _1mA , surge withstand capability, and a life of voltage application. It is to provide a resistor.

[0006]

The present invention uses bismuth as a base material.
Converted to i ₂ O ₃ 0.3 to 1.2 mol%, converted antimony to Sb ₂ O ₃ 0.3 to 1.5 mol%, converted chromium to Cr ₂ O ₃
0.3 to 1.0 mol%, Cobalt converted to Co ₂ O ₃ 0.3 to 1.5
mol%, manganese converted to MnO ₂ 0.2 to 0.8 mol%, silicon converted to SiO ₂ 4.0 to 10.0 mol%, nickel to N
Converted to iO 0.3 to 2.5 mol%, converted aluminum to Al ₂ O ₃ 0.002 to 0.02 mol%, converted boron to B ₂ O ₃
0.0001 to 0.05 mol%, converted to Ag ₂ O for silver 0.0001 to 0.05
It contains at least one of mol% and 0.0005 to 0.015 mol% potassium converted to K ₂ O and 0.0005 to 0.015 mol% sodium converted to Na ₂ O, the balance being zinc oxide, and a current of 1 mA. Limit voltage V _1mA to 330-500V / m
It relates to a voltage non-linear resistor characterized by being m.

[0007]

According to the present invention, the change rate Δ of the varistor voltage after the application of surge is changed by adopting the above-mentioned specific composition.
It is possible to provide a voltage non-linear resistor having a small V _1mA , a limited voltage ratio V _40KA / V _1mA , a surge withstand capability, and an excellent life span.

Bismuth is converted to Bi ₂ O ₃ and is 0.3 to 1.2.
Use mol%. Bismuth forms a grain boundary layer between zinc oxide particles and is an important additive that is considered to be involved in the formation of a Schottky barrier related to the development of varistor characteristics. If it is less than 0.3 mol%, ΔV _1mA ,
V _40KA / V _1mA increases, and surge withstand capability deteriorates.
On the other hand, if it exceeds 1.2 mol%, ΔV _1mA becomes large and the surge withstand capability deteriorates.

Antimony and chromium are Sb ₂ O ₃
And Cr ₂ O ₃ , Sb ₂ O ₃ 0.3 to 1.5 mol%, Cr
₂ O ₃ 0.3 to 1.0 mol% is used. Antimony and chromium react with zinc oxide to form a spinel phase, thereby suppressing abnormal grain growth of zinc oxide particles and improving the uniformity of the sintered body. 0.3 mol converted to Sb ₂ O ₃
When it is less than%, ΔV _1mA becomes large and the surge withstand capability deteriorates, and when it exceeds 1.5 mol%, the surge withstand capability deteriorates. Further, when the amount converted to Cr ₂ O ₃ is less than 0.3 mol%, ΔV _{1 mA} becomes large, and the service life is deteriorated, and when it exceeds 1.0 mol%, ΔV _{1 mA} becomes large and V _40KA / V _1mA also increases.

Cobalt is 0.3 to 1.5 mo in terms of Co ₂ O _3.
Use l%. In addition, manganese is converted to MnO ₂ of 0.2 to
Use 0.8 mol%. Cobalt and manganese partly dissolve in the zinc oxide particles and partly precipitate in the grain boundary layer to increase the height of the Schottky barrier.
It is also considered to be related to the stability of barriers. Co
_{If the} amount converted to ₂ O ₃ is less than 0.3 mol%, ΔV _1mA becomes large, and if it exceeds 1.5mol%, ΔV _1mA also _remains.
Grows larger. Also, if the conversion amount to MnO ₂ is less than 0.2 mol%, the service life will deteriorate, and if it exceeds 0.8 mol%,
After all, the service life becomes worse.

It is preferable that Co ₃ O ₄ is contained in the cobalt raw material from the viewpoint of improving the characteristics. In reality, Co ₂ O ₃ and Co ₃ O ₄ are contained.
It is also possible to use mixtures with ₄ .

Silicon is 4.0 to 10.0 mol in terms of SiO _2.
Use%. Silicon is deposited in the grain boundary layer as zinc silicate and has an effect of suppressing grain growth of zinc oxide particles. It is preferable to use amorphous silica because the reactivity is improved and the characteristics are improved. If the amount converted to SiO ₂ is less than 4.0 mol%, V _40KA / V _1mA also increases and the surge withstand capability deteriorates. If this exceeds 10.0 mol%, ΔV _1mA , V _40KA /
V _1mA increases.

Nickel is 0.3 to 2.5 mol% converted to NiO
To use. If the amount converted to NiO is less than 0.3 mol%,
V _40KA / V _1mA increases, and surge withstand capability deteriorates.
If this exceeds 2.5 mol%, ΔV _1mA and V _40KA / V
_1mA increases.

Aluminum is converted to Al ₂ O ₃ and 0.002 to
Use 0.02 mol%. 0.002 mol% converted to Al ₂ O ₃
If it is less than, V _40KA / V _1mA is increased, surge resistance is deteriorated. If this exceeds 0.02 mol%, ΔV _1mA
Grows larger.

Boron is 0.0001 to 0.05 when converted to B ₂ O _3.
Use mol%. If the amount converted to B ₂ O ₃ is less than 0.0001 mol%, the life of _charging becomes worse, and if it exceeds 0.05 mol%, ΔV _1mA and V _40KA / V _1mA increase. Silver is Ag ₂
Use 0.0001 to 0.05 mol% in terms of O 2. If the amount converted to Ag ₂ O is less than 0.0001 mol%, V _40KA / V _1mA increases and the surge withstand capability deteriorates. If this exceeds 0.05 mol%, ΔV _{1 mA} increases.

Both boron and silver have the effect of stabilizing the grain boundary layer. It is preferable to add it as bismuth borosilicate glass containing silver because the electric charge life is improved. The glass may contain another metal oxide such as zinc oxide.

At least one of 0.0005 to 0.015 mol% potassium in terms of K ₂ O and 0.0005 to 0.015 mol% sodium in terms of Na ₂ O is used. It was found that the addition of these had a great influence on the varistor characteristics. Whether potassium or sodium is added or both are to be added, the addition amount of each must be within the range of 0.0005 to 0.015 mol%. The amount added is 0.0005 mol%
If it is less than ΔV _1mA , it will be large, and if it exceeds 0.015mol%, V _40KA / V _1mA will be large and the surge resistance will be deteriorated. If this total amount is 0.002 to 0.005 mol%, ΔV
_1mA becomes smaller. When one of them is added alone, the addition of sodium results in a smaller ΔV _1mA than the addition of potassium. When both are added at the same time, ΔV _1mA becomes smaller, but V _40KA / V _1mA becomes slightly larger than when added alone.

[0018]

EXAMPLES To obtain a voltage nonlinear resistor containing zinc oxide as a main component, first, a zinc oxide raw material adjusted to a predetermined particle size and bismuth oxide and cobalt oxide (preferably Co ₃ O ₄₎ adjusted to a predetermined particle size were prepared. ), Manganese oxide, antimony oxide, chromium oxide, silicon oxide (preferably amorphous), nickel oxide, boron oxide, silver oxide and the like are mixed in a predetermined amount. In this case, silver nitrate or boric acid may be used instead of silver oxide or boron oxide. Bismuth borosilicate glass containing silver is preferably used. Further, the additive may be calcined at 800 to 1000 ° C., then pulverized and adjusted to a predetermined particle size, and the zinc oxide raw material may be mixed. At this time, a predetermined amount of binder (for example, polyvinyl alcohol aqueous solution), dispersant, and the like are added to these raw material powders. Aluminum is also preferably added in the form of an aluminum nitrate solution.

To contain sodium and potassium in the voltage non-linear resistor, for example, an aqueous solution of sodium or potassium carbonate or nitrate is added to the raw material, or glass containing sodium or potassium is added to the raw material. Good to add.

Next, vacuum deaeration is performed preferably at a vacuum degree of 200 mmHg or less, and the water content of the mixed slurry is adjusted to about 30 to 35 wt%.
The viscosity of the mixed slurry is preferably 100 ± 50 cp. Next, the obtained mixed sludge is supplied to a spray dryer to have an average particle size of 50 to 150 μm, preferably 80 to 120 μm, and a water content of 0.5 to 2.0 wt%, more preferably 0.7 to 1.2 wt%.
Granulate the granulated powder of. Next, in the molding step, the obtained granulated powder is molded into a predetermined shape under a molding pressure of 400 to 1000 kg / cm ² .

Next, the molded body is heated / cooled at a temperature of 10 to 100 ° C.
/ hr At a temperature of 400 to 700 ℃, scatter and remove organic components to obtain a defatted body. Next, the degreased body is heated up to 800-
Baking is performed at 1000 ° C for a holding time of 1 to 5 hours to obtain a calcined body.

Next, a high resistance layer is formed on the side surface of the calcined body. In this example, a mixture paste for insulation coating having a predetermined amount of bismuth oxide, antimony oxide, zinc oxide, silicon oxide, etc., added with ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as an organic binder, has a thickness of 30 to 300 μm. Apply to the side of the calcined body.

Next, this is heated / cooled at a rate of 20 to 100 ° C./hr,
Maximum holding temperature 1000 to 1300 ℃, preferably 1050 to 1250 ℃, 3
Main firing is performed under the condition of ~ 7 hours.

Thereafter, a glass paste obtained by adding ethyl cellulose, butyl carbitol, n-butyl acetate or the like as an organic binder to glass powder is applied to the high resistance layer on the side surface in an amount of 50 to 50.
Apply it to a thickness of 300 μm and raise and lower the temperature in air at a rate of 50 to 200.
It is preferable to form the glass layer by heat-treating at 400 ° C./hr and 400 to 550 ° C. for a holding time of 0.5 to 2 hours.

After that, both end faces of the obtained voltage non-linear resistor are polished with a diamond grindstone or the like. Next, after cleaning the polished surface, electrodes are provided, for example, by spraying, on both polished end surfaces by, for example, aluminum or the like to obtain a voltage nonlinear resistor.

Next, according to the above-mentioned manufacturing method, a voltage nonlinear resistor having each composition shown in the following table was manufactured. This resistor has a disk shape with a diameter of 47 mmφ and a width of 22.5 mm.
However, silicon uses amorphous silica, boron and silver are used after vitrification, Co ₃ O ₄ is used as a cobalt source,
The aluminum used the aluminum nitrate solution. V _1mA per unit width is 330 to 500V / mm, but 400 to 450V / m
m is more preferred. The V _1mA / V ₁₀ μ _A is preferably 1.5 or less.

Among the characteristics of the voltage non-linear resistor, V
₁₀ mu _A, V _1mA and V _{40 kA} indicates a limit voltage generated between the electrodes of the two end faces when the respective 10μA to the resistor of the disk-shaped, is 1mA and 40 kA current flow. ΔV _1mA is the reverse direction V after lightning surge (4 / 10μs, 120KA, twice) application
_The change rate (%) was _{1 mA} . The surge withstand rate is indicated by the pass rate (%) after applying lightning surge (4/10 μs, 120KA, twice). The life span was shown by the presence (x) and absence (o) of thermal runaway after 1000 hours of electricity at a temperature of 130 ° C and an electricity rate of 95%. The samples shown in Tables 1 and 2 are all examples according to the present invention, and the samples shown in Tables 3 and 4 are all comparative examples.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

INDUSTRIAL APPLICABILITY In samples 1 and 2 and sample 29.30 of Table 1, the bismuth content is 0.3 or 1.2 mol.
%, But the characteristics are good. Samples 2 and 26 in Table 3
In _{Example 1} , although the bismuth content was 0.1 mol%, ΔV _1mA and V _40KA / V _1mA increased, and the surge withstand capability deteriorated. In samples 3 and 27 of Table 3,
Bismuth content is 1.5 mol%, ΔV _1mA
Became larger and the surge resistance was worse. In Samples 3 and 4 of Table 1 and Sample 31.32 of Table 2, the antimony content is 0.3 or 1.5 mol%, but the characteristics are good. In Sample 4 of Table 3 and Sample 28 of Table 4, the content of antimony is 0.1 mol%,
ΔV _1mA increased and the surge withstand capability deteriorated. In Sample 5 of Table 3 and Sample 29 of Table 4, the antimony content was 2.0 mol%, but the surge withstand capability deteriorated. In Samples 5 and 6 of Table 1 and Sample 33.34 of Table 2, the chromium content is 0.3 or 1.0 mol%, but the characteristics are good. In Sample 6 of Table 3 and Sample 30 of Table 4, the content of chromium was 0.1 mol%, but ΔV _1mA was large, and the voltage application life was deteriorated. In Sample 7 of Table 3 and Sample 31 of Table 4, the chromium content was 1.5 mol%, but ΔV _1mA increased and V _40KA / V _1mA also increased. In Samples 7 and 8 of Table 1 and Sample 35.36 of Table 2, the cobalt content is 0.3 or 1.5 mol%, but the characteristics are good. In Sample 8 of Table 3 and Sample 32 of Table 4, the cobalt content was 0.1 mol%, but ΔV
_1mA increased. Sample 9 of Table 3 and Sample 33 of Table 4
In, the cobalt content was 2.0 mol%, but ΔV _{1 mA} increased. In Samples 9 to 11 of Table 1 and Samples 37 to 39 of Table 2, the aluminum content is 0.002 to 0.02 mol%, but the characteristics are good. In Sample 10 of Table 3 and Sample 34 of Table 4, the aluminum content was 0.001 mol%, but V _40KA / V _1mA increased, and the surge withstand capability deteriorated. In Sample 11 of Table 3 and Sample 35 of Table 4, the aluminum content is 0.03 mol%, but ΔV
_1mA increased. In Samples 12 and 13 of Table 1 and Samples 40 and 41 of Table 2, the content of manganese is 0.2.
~ 0.8mol%, but the characteristics are good. In Sample 12 of Table 3 and Sample 36 of Table 4, the manganese content was 0.1 mol%, but the voltage application life was deteriorated.
In Sample 13 of Table 3 and Sample 37 of Table 4, the manganese content was 1.0 mol%, but the voltage application life was deteriorated. Samples 14 to 16 in Table 1 and Samples 42 to 44 in Table 2
In, the content of silicon is 4.0 to 10.0 mol
%, But the characteristics are good. In Sample 14 of Table 3 and Sample 38 of Table 4, the content of silicon was 3.0 mo.
Although it was 1%, V _40KA / V _1mA also increased and the surge resistance deteriorated. In sample 15 of table 3 and sample 39 of table 4, the silicon content is 12.0 mol%,
ΔV _1mA and V _40KA / V _1mA increased. In Samples 17 and 18 of Table 1 and Samples 45 to 46 of Table 2, the nickel content is 0.3 to 2.5 mol%, but the characteristics are good. In Sample 16 of Table 3 and Sample 40 of Table 4, the nickel content is 0.1 mol%,
V _40KA / V _1mA increased and the surge withstand capability deteriorated. In Sample 17 of Table 3 and Sample 41 of Table 4, the nickel content was _{3.5 mol} %, but ΔV _1mA and V _40KA / V _1mA were large. Samples 19 to 2 in Table 1
1 and Samples 47 to 49 in Table 2 have a boron content of 0.0001 to 0.05 mol%, but the characteristics are good. In Sample 18 of Table 3 and Sample 42 of Table 4, the content of boron was 0.0 mol%, but the voltage application life was deteriorated. In Sample 19 of Table 3 and Sample 43 of Table 4, the content of boron is 0.1 mol%,
ΔV _1mA and V _40KA / V _1mA increased. In Samples 22 to 24 in Table 1 and Samples 50 to 52 in Table 2, the content of silver is 0.0001 to 0.05 mol%, but the characteristics are good. In Sample 20 of Table 3 and Sample 44 of Table 4, the content of silver was 0.0 mol%, but V
_40KA / V _1mA increased and the surge withstand capability deteriorated. In Sample 21 of Table 3 and Sample 45 of Table 4, the content of silver was 0.1 mol%, but ΔV _1mA was large. In Samples 25 to 28 in Table 1, the sodium content is 0.0005 to 0.015 mol%, but the characteristics are good. In sample 22 in Table 3, the sodium content is 0.0003 mol%, but ΔV _{1 mA}
Has grown. In sample 23 of Table 3, the content of sodium is 0.025 mol%, but V _40KA / V
_1mA increased and surge withstand capability deteriorated. In samples 53 to 56 in Table 2, the content of potassium is 0.000.
Although it is 5 to 0.015 mol%, the characteristics are good.
In sample 24 of Table 3, the content of potassium is 0.0
Although it was 003 mol%, ΔV _{1 mA} increased. In sample 25 of Table 3, the content of potassium is 0.02.
Although it was 5 mol%, V _40KA / V _1mA increased and the surge resistance deteriorated. As is clear from the above results, according to the present invention, the change rate ΔV _1mA of the varistor voltage after lightning surge application is small (less than 10%) and the limiting voltage ratio V _40KA / V _1mA (less than 2.1). It is possible to provide a voltage non-linear resistor which is also small in size and has a very good surge withstand capability and a very long service life. As a result, the arrester can be made more compact and lightweight.

Claims (1)

[Claims] 1. The amount of bismuth converted to Bi ₂ O ₃ is 0.3 to 1.2.
mol%, 0.3 to 1.5 mol% of antimony converted to Sb ₂ O ₃ , 0.3 to 1.0 mol% of chromium converted to Cr ₂ O ₃ , 0.3 to 1.5 mol% of cobalt converted to Co ₂ O _3. , Manganese converted to MnO ₂ 0.2 to 0.8 mol%, silicon converted to SiO ₂ 4.0 to 10.0 mol%, nickel converted to NiO 0.3 to 2.5 mol%, aluminum converted to Al ₂ O ₃ . to 0.002 to 0.02 mol%, boron B ₂ O ₃ 0.0001~0.05 mol% in terms of silver and in terms of Ag ₂ O 0.0001~0.05 mol%, and 0.0005 in terms of K ₂ O to 0.015 mol% potassium and Na ₂
A voltage non-linearity characterized by containing at least one of 0.0005 to 0.015 mol% sodium in terms of O, the balance consisting of zinc oxide, and a limiting voltage V _1mA for current 1 _mA of 330 to 500 V / mm. Resistor.