JPS61256701A - Oxide resistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a novel oxide resistor, and particularly to an oxide resistor suitable for absorbing switching surges in circuit breakers and the like.

[Background of the invention]

Conventionally, aluminum oxide-clay-carbon compositions have been known as resistors for circuit breakers, with a resistance value of approximately 400 Ω and a circuit breaker switching surge resistance of 500 J/cm.
(hereinafter abbreviated as J/cm3), a resistance temperature coefficient of 19×10''/C (20 to 250C), and a maximum operating temperature of 200C.

Recently, as power transmission voltages have become higher, there has been a strong demand for linear resistors for circuit breakers to be smaller and lighter, so resistors should (1) have increased switching surge resistance; (
2) Although the temperature will rise if a switching surge is injected, the resistance value should have little variation even when exposed to high temperatures. (3) The temperature coefficient of resistance is positive. (4) Materials whose voltage-current characteristics change linearly are required. The linearity of the voltage-current characteristic here is approximately expressed as I (current) = K (constant 1 x V (IIE voltage 1'), and it is desired that α is 1.3 or less.

Conventionally, carbon powder-dispersed ceramic resistors used in circuit breaker resistors are sintered in an inert gas atmosphere to prevent carbon combustion, and the resistance value is controlled by the amount of carbon powder mixed. . (1) When this resistor is exposed to temperatures of 4,000 degrees or higher, the carbon is oxidized and its resistance value changes. (2) The temperature coefficient of resistance is negative and -9Xi O"/l:' (20~
250C), the resistance decreases as the temperature rises, and when the voltage is constant, a sudden increase in current generates even more heat, leading to a runaway condition.

Therefore, as the resistor 7, a ceramic resistor whose basic component is zinc oxide, which is an oxide that does not cause combustion, is known from Japanese Patent Application Laid-Open No. 55-57219. The present inventors have discovered that conventional oxide resistors mainly composed of zinc oxide do not fully satisfy the above-mentioned required characteristics, and have arrived at the present invention.

[Purpose of the invention]

The purpose of the present invention is to have a resistance value of 40 to 4000 Ωα, good linearity of voltage-current characteristics, excellent switching surge resistance of the circuit breaker, and resistance value that does not change even when exposed to high temperatures of 500C or higher. is low, and the temperature coefficient of resistance is -I x 10"
An object of the present invention is to provide an oxide resistor having a range of 3/C to +4 X 1 o-''/C.

[Summary of the invention]

The present invention provides a sintered body made of a composite oxide containing zinc oxide as a main component and an oxide different from the zinc oxide as a subcomponent, the sintered body having a temperature coefficient of resistance at 20 to 500C of 5 ”'Ω/C~-5X10”Ω/C
, resistance value at 20C is 100 to 4000 Ωcm, switching surge resistance is SOO to 800 J 7cm” and 3×
The voltage nonlinear coefficient at lO-”~80 persons/cd is 1.
0 to 1.3.

Furthermore, the present invention comprises a sintered body mainly composed of zinc oxide and containing 1 to 20 moles of magnesium oxide and 0.1 to 20 moles of at least one of gallium oxide, lanthanum oxide, and indium oxide alone or in total, An oxide resistor is characterized in that a low resistance layer having a lower resistance value than zinc oxide is formed between zinc oxide crystal grains.

Particularly preferred is a sintered body consisting of iIO-9th zinc oxide, 3-10% magnesium oxide, 5-15% aluminum oxide aluminum pentide, and 1-2-2% silicon oxide in a 1 molar ratio.

Crystal grains made of zinc oxide and 100Ω to 4x10”Ω
It is a composite sintered body with crystal grains that exhibit an electrical resistance value of , and between the zinc oxide crystal grains there is a grain boundary layer that has a lower electrical resistance than the zinc oxide grains. This sintered body is plate-shaped. It may be columnar or cylindrical, and electrodes are formed on both end faces. The electrode is formed on the entire surface with some edges remaining, and is coated with Atmium by thermal spraying etc.
Metals such as these are formed into a film.

A grain boundary layer having the same electrical resistance value as the zinc oxide crystal grains may exist between each crystal grain. It is desirable that the crystal grains of zinc oxide compounds and oxides other than zinc oxide have a resistance higher than that of zinc oxide in the range of 100Ω to 4×10”Ω. Zinc oxide compounds and oxides other than zinc oxide have the following chemical formula: That is, in order to further improve the linearity of voltage-current characteristics, ZnYxO4, Z is added to the basic component MgO.
nGat04tZ n L a204 1 Z ” A
T,! oa * Z n I ”*Os BMgAL
xOir MgYsOa * MllGazOa,
MgLa204.

MgInz04t AtzOs * YxOs * G
X selected from a*031Lashs and InaOs
It is to contain S class or higher. In order to form these compounds, aluminum (
All, yttrium (Y), gallium (Ga).

Addition of metal or metalloid elements such as lanthanum (La+) and indium (Inl).

The use of bismuth (Bi) is undesirable. This is because when Bi is used, a high resistance layer is likely to be formed in the grain boundary phase.

The basic ingredients of the raw material for the sintered body are zinc oxide (ZZIO) and magnesium oxide (MgO), with zn as a subcomponent.
Q, trivalent metals other than MgO, metalloid oxides such as aluminum oxide (AtzOs), yttrium oxide (Y2O
3), gallium oxide (Q a2Qs l .

Lanthanum oxide (Lag's) and indium oxide (I
n2Q3).

The sintered body is manufactured by, for example, thoroughly mixing the above-mentioned oxide raw material powder, adding water and a suitable binder such as polyvinyl alcohol, granulating the mixture, and molding the mixture using a mold. The molded body is heated at 1200 to 1600 C in the atmosphere using an electric furnace.
It is fired at a temperature of Both end faces of the fired sintered body that form electrodes are polished and adjusted, and electrodes are formed by electrospraying or baking.

The obtained resistor may be provided with a high-resistance ceramic layer or a glass layer on the side surface of the resistor in order to prevent creeping discharge during use. Note that the obtained resistor generally exhibits linearity, but if it exhibits nonlinearity, it is effective to apply a high voltage to destroy the high resistance portion (particularly the grain boundary layer).

The inventors of the present invention have studied various ways to reduce the weight and weight of the resistor, and have found that (1) the resistor used has a resistance value of 40 to 4000;
Ω, and the opening/closing surge withstand capacity is 400 J/cm” or more.
The non-linear coefficient of voltage-current characteristics, α, is 1.3 or less, and the temperature coefficient of resistance is -I x 10-3. Q: from +4X10-”
/l:' (20 to 500C) and the resistance value change must be within ±10 inches even after exposure to high temperatures of 500C or higher. B) The switching surge withstand capacity of a resistor is affected by the generation of many types of crystal grains with different resistance values in the resistor and the specific gravity of the resistor; (3) the voltage of the resulting resistor;
It has been found that the linearity of current characteristics improves when trivalent metal/metalloid oxides are added. Figure 1 is a schematic diagram of the microstructure of the resistor obtained, and Figure 2 is the specific gravity (g/Bi3) of the resistor.
Relationship between and opening/closing surge withstand capacity (J/cm"), 3rd
The figure is a diagram showing the voltage-current characteristics of the obtained resistor. It is conceivable to select raw materials for use in the resistor that are easy to sinter, that react with each other to produce new crystal grains with different electrical resistance, and that the resulting sintered body has a high specific gravity. Therefore, a resistor that uses zinc oxide and magnesium oxide as basic components and adds aluminum oxide, yttrium oxide, gallium oxide, lanthanum oxide, indium oxide, etc. to improve the linearity of the voltage-current characteristics of the resulting oxide resistor. We investigated the characteristics of the body. As a result, (1)
The opening/closing surge resistance is 800 J/cm3, which is about 1 lower than that of conventional products.
．． (2) The temperature coefficient of resistance is significantly higher by 6 times.
The content of O) changes from negative to positive and is improved;
3) The linearity of the resistance value and voltage-current characteristics is determined by the basic component Z.
nO, MgO with aluminum oxide (At20s) *
Yttrium oxide (YzOs).

Galium oxide (GazOm) is converted into lanthanum oxide (L at
It has been discovered that this can be improved by adding O3) + indium oxide (In2Q3), etc.

Ru. The temperature coefficient of resistance of MgO changes greatly from negative to positive by changing the content, and the temperature coefficient varies from -I x 10-3Ω/C to +4X10'' at least within the above composition range.
It becomes larger than Ω/C. Furthermore, if the amount of MgO is increased beyond the above composition range, the switching surge withstand capacity becomes smaller than 400 J/3, which is preferable as a resistor for circuit breakers.
t, subcomponent kl-gos t YxOs s G
In the case of ados a L a203 s I "ZOS, if the composition exceeds the above range, the resistance value will be higher than 400Ω, and the switching surge resistance will decrease, making it unsuitable as a resistor for circuit breakers. However, , AtzOs
+ YsOs, Gazes pLazos *I
By adding nzOs, the resistance value can be controlled and the linearity of voltage-current characteristics can be improved. The reason for this is considered as follows. That is, the subcomponent A Z 203 +Ga
zes, In2O3, La2. s reacts with (1) mainly basic components ZnO and MgO to form Z n A t20
41ZnY*04. zrt()ao, , ZnLa
204. ZnIn20a.

MgkLzO< , Mg Y2O4, MgG az0
4゜MgL a20a e Mg I n2o4 crystal grains are generated, and the electrical resistance of the generated crystal grains is from 500Ω to 4 (2) Ats Y, Ga, La,
This appears to be caused by diffusion of In and increasing the carrier concentration of ZnO crystal grains.

A particularly desirable composition of the resistor of the present invention is ZnO mole, Inz030.02~5#-4%, Lag's0
．． At least one of 1 to 10 + divine chi is added.

[Embodiments of the invention]

(Example 1) Basic component Zn03420g (84(-le%), MgO
iolg (5 molti), At203 as a subcomponent
510g (10mol cs), Ga20347g (0,5
mol %) and In*03369g (0.5 mole) were accurately weighed and mixed in a ball mill for 15 hours. After the mixed powder is dried, 5% by weight of polyvinyl alcohol aqueous solution is added to the dry raw material powder and granulated. The granulated powder is made using a mold with a molding pressure of 450 and 9/- 35 mφ x 20
Mold into 1. The molded body was fired in the atmosphere at 1350 tZ' for 3 hours. The rate of temperature rise and fall at this time is 70C
/h. The drowsiness resistance of the crystal grains produced in the obtained sintered body is about 10 to 50 Ω for ZnO crystals, and about 70 to 1 for ZnO crystals, respectively.
00Ω ZnAt204 crystal, approximately 400Ω M g O
Crystal, ZnGaz of about 700-4xlO"Ω, 04.Z
nLa204. ZnYzO4゜Z n I nz 03
, MgAt204, MgY2O4, MgGa
z04゜MgY2O4, Mg Inz03. Atz
Os, Ga2O3.

La2O5, InzOs.

Separately, Asahi Glass Exhibition ASF-1400 with low melting point crystallized glass
GALA

-.2 was heat-treated at 750C for 130 minutes in the atmosphere to bake the glass. Both end faces of the glass-covered sintered body were polished by approximately α5 using a lap master and washed with trichlorethylene. An At electrode was formed on the cleaned sintered body by thermal spraying to obtain a resistor.

This invention product and conventional product (carbon dispersed ceramic resistor)
Table 1 shows a comparison of the switching surge withstand capacity, temperature coefficient of resistance, rate of change in resistance value after 5 o'clock heat treatment in the atmosphere, and non-linear coefficient α of voltage-current characteristics.

It can be seen that the product of the present invention has an extremely better switching surge resistance and a smaller voltage nonlinear coefficient α than the conventional product. The temperature coefficient of resistance of the present invention is positive, the AC withstand capacity at 100 μs is 20 A or more, and β in the VI characteristic is 0.
It is 9-1.0.

The electrical resistance of the crystal grains was measured by mirror polishing the sintered body, analyzing it with a scanning electron microscope, forming fine electrodes on the surface of each crystal grain, and measuring from the current and voltage.

An example of the cross-sectional structure of the oxide resistor of the present invention is shown in FIGS. 4 and 5. In FIG. 4, 1 is a sintered body, 2 is an electrode,
3 is a film of crystallized glass or ceramic material. Here, the reason why a film of crystallized glass or a ceramic material is provided on the side surface of the sintered body is to prevent creeping discharge during use.

C Example 2) was changed to 0.05 to 20 molt, and k1 was added as a subcomponent.
403. YzOs, Lazos, Inx
os and Gazes, and the blended amount was accurately weighed. The weighed raw material powder was exposed to 130% in the atmosphere as in Example 1.
It was fired by holding at a temperature of 0 to 1600C for 3 hours. The densities of the obtained sintered bodies were each 95 to 98 inches of the theoretical density. Both ends of the fired sintered body are wrapped with a lap master of approx.
It was polished wxf and ultrasonically cleaned with trichlorethylene. The cleaned sintered body was used as a resistor by forming an At sprayed electrode. Table 2 shows the resistance value, switching surge resistance, resistance temperature coefficient, and voltage nonlinear coefficient α of the obtained resistor.

From Table 2, composition numbers 10-121 composition numbers 16-18
9 Composition numbers 21-231 Composition numbers 27-299 Composition numbers 32-36, i.e. Z with basic components 80-929 molti
nO contains 5 to 15 mol% MgO, and further contains Al as a subcomponent! os 5-15# Takashi, Y2O2 0
, 5-5 studies → Chi, La103 0.3-1 Zeroto%,
The characteristics of a resistor to which one or more components selected from 0.5 to 5 moles of G azOs and 0.1 to 5 moles of In2O3 are added have a resistivity of 110.
~3500Ωcm, opening/closing surge resistance is SOO~780
J/ar1'% resistance temperature coefficient is -5X 10-'Ω/
C or less, +4.3×10 −'Ω/C or less, and the voltage nonlinear coefficient α is 1.02 to 1.3, which indicates that it is excellent as a resistor for a circuit breaker.

Also, from the wc2 table, the opening/closing surge resistance is determined by the basic component ZnO.
It can be seen that this can be improved by adding MgO to . However, if MgO is contained too much (20 mol%) (47), the power consumption is 300 J/cm", compared to 500 J/lyn" of the conventional product.
Yoshi also becomes low. In addition, by changing the content of MgO, the temperature coefficient of resistance changes from negative to positive, and if the amount of MgO added is -xxxo-"/l:' or less, +4
It can be seen that the resistance value can be reduced to less than
Although it does not show a large change in the range of 3 to 500Ω, the subcomponents ktzos*YzOs, Lados,
G axis and InzOs are subcomponents AttOs +
YxOs * Law's, Ga5es +In
1.0 by selecting the optimal addition amount of zOs etc.
2 to 1.2, which can be significantly improved, but the subcomponent A
ttOs * YzOn , Law's , Ga *
It can be seen that if the amount of 03°I n*os added is increased too much, the opening/closing surge resistance decreases.

For these reasons, a particularly desirable composition for a resistor for a circuit breaker is a mixture in which the basic component is ZnO containing 5 to 15 moles of MgO, and the subcomponents are 0.3 to 1% of Nell #-+% and La gos. Uryo%, G
azes Nell 0, 5~5-116, InzOs 0.1~5-5ep
It is better to add -4%.

(Example 3) Figures 6 and 7 show the oxide resistor of the present invention in each GCB.
This shows an example of application for use in making resistance and SFa gas insulated neutral point grounding (NGR). The resistor 5 used in FIGS. 6 and 7 has a cylindrical shape as shown in FIG.

〔Effect of the invention〕

As explained above, 1. According to the present invention, the switching surge resistance is extremely high, the voltage nonlinear coefficient of the voltage-current characteristic is small, the resistance temperature coefficient is positive and small, and the resistance temperature change after heat treatment at 500C is small. This has the effect that a high-quality oxide resistor can be obtained.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the cross-sectional structure of an oxide resistor according to an example of the present invention, Figure 2 is the relationship between the specific gravity of the oxide resistor and the switching surge withstand capacity of the circuit breaker, and Figure 3 is the oxide resistance Body voltage-
@Sales availability, Figures 4 and 5 are cross-sectional views of oxide resistors according to embodiments of the present invention, Figure 6 is a configuration diagram of a GCB closing resistor, and Figure 7 is an 8Fa gas insulated resistor. Sex point grounding (N
GR) is a configuration diagram. 1.5...Oxide resistor, 2...Electrode, 3...Glass etc., 4...Cylinder interior, 6...Bushing, 7...
...Tank, 8...Capacitor, 9...Shutoff part, 1
0... Oil dash pot, 11... Piston for opening/closing operation, 12... Air tank.

Claims (1)

[Claims] 1. A sintered body made of a composite oxide containing zinc oxide as a main component and an oxide different from the zinc oxide as a subcomponent, the sintered body having a temperature coefficient of resistance at 20 to 500°C. is 5×10^-^4l/℃~-5×10^-^4l/℃,
Resistance value at 20℃ is 100-4000Ωcm, switching surge resistance is 500-800J/cm^3 and 3×10
An oxide resistor characterized by having a voltage nonlinear coefficient of 1.0 to 1.3 at 3 to 80 A/cm3. 2. Zinc oxide is the main component, magnesium oxide is 0.1~
consisting of a sintered body containing 10 mol% and 0.1 to 20 mol% of at least one of aluminum oxide, gallium oxide, lanthanum oxide, and indium oxide alone or in total amount,
An oxide resistor characterized in that a low resistance layer having a resistance value lower than that of zinc oxide is formed between zinc oxide crystal grains. 3. The oxide resistor according to claim 2, which is a sintered body consisting of 70 to 92% zinc oxide, 3 to 10% magnesium oxide, and 5 to 15% aluminum oxide in molar ratio. 4. The sintered body according to claim 2, which is a sintered body consisting of 68 to 90% zinc oxide, 3 to 10% magnesium oxide, 5 to 15% aluminum oxide, and 1 to 2% silicon oxide in molar ratio. Oxide resistor.