JPS61281501A - 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 an oxide resistor, and in particular has a small resistance temperature coefficient, linear voltage-current characteristics, and absorbs switching surges of circuit breakers, etc. The present invention relates to an oxide resistor suitable for.

[Background of the invention]

Conventionally, aluminum oxide-clay-carbon compositions have been known for resistors for circuit breakers, and have a resistance value of about 40.
0Ω・crn1 discharge capacity is 500 joules, 7cm”
(hereinafter referred to as "J/crn"), a negative temperature coefficient of resistance of 19x19-ly/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 smaller and larger resistors used in circuit breakers. For this reason, the resistor to be used must (1) have a large alignment withstand capacity, (2) the temperature of the resistor will rise when a discharge surge is injected, but the fluctuation in resistance value will be small even if the temperature rises; (3) ) It is desirable that the p resistance temperature coefficient is positive, but it must be within the range of at least -1 and 191 Ω/C to +4 × 10-1 Ω/C, and (4) the voltage-current characteristics should be quantified linearly. Materials required. child\.

Then, the voltage-current linearity is approximately I(current)-K
(constant) x v (voltage)'', and it is desired that α is 1.3 or less.

Conventionally, carbon powder dispersed ceramic resistors used for circuit breaker resistors are sintered in an inert gas atmosphere to prevent the carbon powder from burning during sintering, and the resistance value is determined by the carbon powder content. controlled by quantity.

(1) When this resistor is exposed to a temperature of 400t:' or higher, carbon is oxidized and the resistance value fluctuates. (2) Resistance temperature coefficient is negative -9X10"Ω/C (20~zbO2T)
Because of the large temperature, the resistance value decreases when the temperature rises by absorbing discharge surges, and when the voltage is constant, the rapid increase in current generates more heat, leading to thermal runaway. For this reason, when using a carbon powder dispersed resistor, the shape of the resistor is made sharper to reduce the absorbed energy per unit volume. However, with this method, problems arise such as the container such as an insulator that holds the resistor becomes large and expensive, and the equipment such as the circuit breaker becomes large and requires a large installation area. .

Therefore, as a resistor, (1) it must be an oxide-based material that will not burn and cause a change in resistance even if it generates heat;
2) The temperature coefficient of resistance is small, preferably positive, and does not cause an increase in current when the temperature increases. For this purpose, it has been found that an oxide resistor containing zinc oxide as a main component, silicon and magnesium, and at least one of lithium, copper, and silver is suitable.

In addition, non-linear resistors have been known as resistors containing zinc oxide as a main component, which are conventionally used as surge absorbers and constant voltage elements. However, the resistor targeted by the present invention has completely different characteristics from this resistor.

[Purpose of the invention]

The present invention was made in order to improve the above-mentioned conventional technology, and its purpose is to have a resistance of 40 to 4000 Ω/sub, good linearity of voltage-current characteristics, and a high discharge withstand capacity of the circuit breaker. The resistance value does not change even when exposed to high temperatures of 500C or higher, and the temperature coefficient of resistance is 11 × 10-sΩ.
An object of the present invention is to provide an oxide resistor having a resistance in the range of /C to +4 x 10-8 Ω/C.

[Summary of the invention]

The main component of the oxide resistor of the present invention is zinc oxide.

Magnesium oxide, silicon oxide, lithium oxide, copper oxide,
A composite oxide sintered body made up of particles of zinc oxide and particles of an oxide of a metal or metalloid element other than zinc, to which a metal or metalloid oxide such as silver oxide is added. 3.7X from 70Ω with particles consisting of zinc
It is a composite sintered body with particles exhibiting an electrical resistance value of 10''Ω, and this sintered body is plate-shaped or cylindrical, and electrodes are formed on both end faces.

A grain boundary layer having an electrical resistance equivalent to that of zinc oxide particles may exist between each crystal grain. Particles of zinc oxide flavorings and acid products excluding zinc oxide are 70Ω/3.7X10"
It is desirable that the resistance be higher than that of zinc oxide in the Ω/sub range. Zinc oxide compounds and oxides other than zinc oxide have the following chemical formulas.

That is, Zn0z8i04. Mg*8i04. Liz
cuOg.

Litai's + Cu2Mg0z, Cu5iO
a, Cuo, st ・Zno, 3oO, Li4Zn
03, Ag 5ins, AgzMgOs+Ag
4zno,, LjiZnS104, SiO2, MgO
, Lf20°CuzOi, and kgxo. In order to form these compounds, silicon (8i) and magnesium (M
g).

This means adding metal or metalloid elements such as lithium (Li), copper (Cu), and silver (Ag), or compounds such as their oxides. The use of bismuth' (old) is desirable. This is because when Bi is used, a high resistance layer is likely to be formed in the grain boundary phase.

The raw material for the sintered body is mainly zinc oxide (ZnO),
Magnesium oxide (MgO) is a subcomponent.

Silicon oxide (SjO*) and lithium oxide (Lj□O)
.

It is selected from one or more of oxidized steel (cuzo) and silver oxide (AgzO).

The method for manufacturing the sintered body is, for example, by thoroughly mixing the 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 fired in the atmosphere at a temperature of 1200 to 1700 C using an electric furnace. Both end faces of the fired sintered body that form the electrodes are polished and adjusted.

Electrospray or baking processes form the electrodes.

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. The obtained resistor shows linearity in voltage-current characteristics, but if it shows non-linearity, the high resistance part (
%, it is effective to completely destroy the grain boundary layer).

The oxide particles are MgOe S S O2+ L' 20
r C” 20 mAgzO,ZnzS+04.Mg2
．． S, 10a, LhCuCh +Li28 iQ 3
, CuCu21V 2 , Cu2 S 10 s
, Cu6,6+ jZn(1,a90+ L i
4ZnOs, Ag2S its + kgz
MgO3゜Ag4ZnOs, L 12Zns 10
1. An oxide resistor comprising: a sulco containing one or more types of 4.

The electrical resistance of the oxide particles is 70Ω to 3°7×1
An oxide resistor characterized in that it has a resistance in the range of 01aΩ, which is higher than that of zinc oxide crystal grains.

Crystal grains made of zinc oxide and 70Ω to 3.7X10”Ω
What is claimed is: 1. An oxide resistor comprising: a composite sintered body with particles having an electrical resistance of , .

[Embodiments of the invention]

As a result of examining various ways to reduce the size and weight of the resistor, the inventors found that (1) the resistor used has a resistance value of 40 to 4000;
Ω・m, and the discharge withstand capacity is 500 J 7cm” or more,
Linear index α of voltage-current characteristics is 1.3 or less, resistance temperature coefficient is -IXIO-”Ω/C to +4X, 10-”Ω/C
(2o~500C) and the change in resistance value is within ±10% even after exposure to high temperatures of 500C or higher. (2)
As shown in FIG. 2, the discharge withstand capacity of a resistor increases as the specific gravity of the resistor increases.

This can be controlled by forming various types of particles with different resistance values in the resistor, as shown in FIG. (3
) As shown in FIG. 3, the voltage-current characteristics of the resistor have a linear relationship between current density and electric field strength. In particular, :[,i
A resistor containing a monovalent metal element such as , Cu, or Ag has good linearity. In other words, Fig. 1 shows the composition of the microstructure of the obtained resistor, Fig. 2 shows the relationship between the resistor's specific gravity (g10y+'') and switching surge resistance (J/crn''), and Fig. 3 shows the obtained resistor. This is the current density-electric field strength characteristic of a resistor.

The raw material used for the resistor is easy to sinter, and the raw material powder reacts with each other to generate new crystal particles with different electrical resistance.
Furthermore, it is necessary that the specific gravity of the obtained sintered body be increased. Therefore, we were able to achieve our goal with a sintered body containing zinc oxide (7, no) as the main component, silicon and magnesium, and one or more of lithium, copper, and silver.

That is, (1) the discharge withstand capacity is 870 J/c- due to the addition of 8iOz to the main component ZnO, which improves the sintered density.
・It is approximately 1.7 times higher than the conventional product □ I, which is significantly higher. (2
) The temperature coefficient of resistance can be improved by changing from negative to positive by changing the amount of MgO added to ZnO, the main component. (3) The linearity of the resistance value and voltage-current characteristics is due to the main component ZnO.
It has been found that all the properties can be improved by adding +Cu 20 +Ag5O and the like.

A desirable composition of the resistor of the present invention is 50≦ZnO and 99.9 mol% of contained elements in terms of oxides.

;1 , 0.5 <°"Oi:<20%"ゞPaゝ"'.

ゝ゛°゛% and 0.01≦1'vhO≦10 mol% (M
is Li.

It contains monovalent elements such as Cu and Ag).

If the amount of Sio2 in the additive exceeds the above composition range, the temperature coefficient of resistance becomes negative and becomes larger than 0-1 Ω/C, making it undesirable as a resistor for a circuit breaker. However, by adding 5to2, the discharge withstand capacity is significantly improved. The reason for this is that when the main components ZnO and 5tos are sintered, Zn18i04 crystals are generated, and the electrical resistance of these crystal particles is 150-300Ω, which is 10-300Ω compared to Zn0M crystal.
This is thought to be because it is higher than 50Ω and further contributes to improving the density of the sintered body. Furthermore, the inclusion of MgO changes the temperature coefficient of resistance from negative to positive. The temperature coefficient of resistance is at least −I X10−IΩ/C than the above composition range.
+4X10"Ω/C also becomes larger.And Mg
If the addition of O is greater than the above composition range, the discharge withstand capacity will be 500%.
J 7 cm", making it unsuitable as a circuit breaker resistor. On the other hand, L l * 0 * Cu in the additive
In the case of *0, Ag m O, if the amount exceeds the above composition range, the resistance value will be higher than 4000 Ω·sub, and the discharge withstand capacity will decrease, making it unsuitable as a resistor for a circuit breaker. However, by adding LIsO, cu, o, Ag*0, the resistance value of the resulting resistor can be controlled and the voltage-current linear characteristic characteristic can be adjusted. The reason for this is considered as follows. That is, Li2O in the additive.

Cu2O and AgzO react with (1) main component ZnO and additives 8102 and MgO to form filzs;
, cu2Mgo! .

CuS io 3. Ag Si(')a, Ag
gMg(,)s, Ag4zno3.

Li2ZnSiO4,Cuo,s+ -Zn(,4gO
ZnO crystal, z
n2sio4 crystal.

(2) Li, ('!u, Ag diffused into the generated ZnO crystal grains).
This seems to be caused by lowering the carrier concentration of the ZnO crystal particles and increasing the resistance of the ZnO particles themselves.

Therefore, a particularly desirable composition of the resistor of the present invention is SiO+total 0.5<S iOz<20 in terms of a single oxide.
mol%, MgO < 30 mol%, and L
' 20 + Cu20 * AI? It is a resistor containing 0.01 to 10 mol% of 2001 or more species, with the balance being ZnO. The electrical resistance of the produced particles was measured by mirror-polishing the sintered body, analyzing it with a scanning electron microscope, and forming a fine electrode on the surface of the crystal to measure it from the current and voltage.

An example of the resistor structure of the present invention is shown in FIGS. 4 and 5.

In FIG. 4, reference numeral 1 indicates a sintered body, 2 indicates an electrode, and 3 indicates a film 4 made of glass or ceramic material, which indicates the inside of the cylinder.

The purpose of providing a film of glass or ceramic material on the side surface of the sintered body is to prevent creeping discharge during use.

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Main component Zn0k 89 mol%, subcomponent S 102
Accurately weigh 5 mol% of k, (total 2 cl% of Ji2cOs, and 5 mol% of MgO) and mix in a ball mill for 15 hours. After drying the mixed powder, add 10 wt% polyvinyl alcohol aqueous solution to the dry raw material powder. Add 1 to 7% by weight and granulate the powder.The granulated powder is molded using a mold at a pressure of 500 kg/c.
m” to a size of 35 mm x 20 mm.The molded body is placed in the atmosphere at 1
Fired again at 350C for 3 hours. The row at this time
The temperature decreasing rate is 70tZ'/h. The particles of the obtained sintered body are ZnO particles with an electrical resistance of about 40 to 90 Ω, which is higher than that of pure ZnO crystals, and about 150 to 300 Ω.
ZnzS104 particles, IJ14 of about 400-750Ω
ZnOa and M g ! 810 g particles, approx. 800 ~
3.7xlO"ΩNo LizsfOaLi2ZnS104
．． Particles such as MgO, 5iOz, and LizO are generated.

Separately, Asahi Glass ASF-1400, a low melting point crystallized glass,
Glass (ZnO-8IQ, -820, series) powder was suspended in an ethyl cellulose/butyl calpitol solution, and this was applied to the side surface of the fired sintered body with a brush to a thickness of 50 to 300 μm. The sintered body coated with the glass paste was heat-treated in the air at 750 tZ' for 30 minutes (7) to bake the glass. Both end faces of the glass-formed sintered body were polished by approximately 0.5 trrm with a lap master, and then polished with trichlorethylene. The sintered body after cleaning was used as a resistor by forming an A7 electrode.

This invention and conventional products (carbon-dispersed ceramic resistor)
Table 1 shows a comparison of discharge withstand capacity, temperature coefficient of resistance, rate of change in resistance before and after heat treatment at 500C in the atmosphere, and linear index α of voltage-current characteristics.

The product of the present invention has greater switching surge resistance than conventional products, has a positive temperature coefficient of resistance, has a linear index close to 1, and has a
It can be seen that the resistance change rate before and after the 0C heat treatment is small and is 7.

The amounts of Sin, L, and MgO were varied from 0.1 to 50 mol%, and 1m selected from LIaO, Cu1O, and Ag2O were varied from 0.01 to 30 mol%, and the blending amounts were accurately weighed. The weighed raw material powders were mixed, granulated, and molded in the same manner as in the examples, and then heated in the atmosphere at a temperature of 1300 to 1600 t:'.
It was held for a while and fired. The density of each sintered body after firing was 94 to 98% of the theoretical density. Both end faces of the obtained sintered body were polished by approximately 0.5 tones using a lap master, and then subjected to ultrasonic cleaning in trichlorethylene. The cleaned sintered body was used as a resistor by forming an At sprayed electrode on the polished surface. Resistance value of the obtained resistor.

Table 2 shows the discharge capacity, temperature coefficient of resistance, and linear index of voltage-current characteristics.

From Table 2, et al., 417-23, AI 7-23.
A26-30. 32 to 37, 440 to 43, that is, to the main component Z1073 to 88-Ele%, 2 to 10 mol% of 5iO1, 2 to 15 mol% of MgO are added, and further 0.01 to 15 mol% of Li2O ,0.01 to 10 mol% of Cu2O and 0.01 to 10 mol% of AgzO are added.The resistor has a resistance value of 40%.
0~4.2X10''Ω・sub, discharge capacity is 490~870
J/cm", the temperature coefficient of resistance is 1 x 10 - +
1.5×10-”Ω/T, linear index α is 1.04 to 1.
3 indicates that it is excellent as a resistor for circuit breakers.

On the other hand, from Table 2, the discharge withstand capacity is 81 (h) for the main component ZnO.
570 J/z" (boiled 2
), which is approximately 2.5 times larger than that when 0.1 mol% addition (AI) is added. However, 8jOi'f
: 340 J/c if added too much (50 mol% (A8))
rn" is lower than the conventional product's 500 J/Crn". The temperature coefficient of resistance changes from negative to positive by adding MgO to the main component ZnO, and can be changed from -IXIO-'Ω/C to -1-4X10-' by selecting the amount of MgO added.
It can be seen that it can be reduced to within Ω/C. The resistance value is about 20 to 600 Ω・cln (A1-16) even if the total amount of S t 02 * M g O added to the generated ZnO is increased, but the resistance value is about 20 to 600 Ω・cln (A1-16), but the resistance value is about 20 to 600 Ω・cln (A1-16),
400Ω・crn to 2X10'Ω depending on the amount of zO added
・It can be seen that there is a significant change from vice versa. Furthermore, the voltage nonlinearity index is determined by the addition of L i20 , Cu20 , A
1.0 by selecting the optimal addition t of gzO etc.
It can be significantly improved to 4 to 1°3. However, LizO,C
It can be seen that if the amount of uzO1Ag20 added is increased too much, the discharge withstand capacity decreases.

However, sample numbers 40 to 43 are resistors containing Li1O, CuzO, and AggO' in combination in the form of a single oxide. In this case as well, all of the target characteristics are satisfied.

For these reasons, a particularly desirable composition for a circuit breaker resistor is Zn0K as the main component, and 8i0 in terms of each oxide.
Add 0.5 to 20 mol% of z, 1 to 30 mol% of MgO, and further add 1fff1 of LizO, C+gO, AgxO.
or more 'ff: 0.01 to 10 mol%.

Embodiment 3 Figures 6 and 7 show the neutral point ( i - Grounding resistor, i.e. BFB gas insulated neutral grounding resistor (
This shows an example applied to N(FR). The cylindrical oxide resistor 5 shown in FIG. 5 of the present invention is insulated! 7'f
, and are incorporated into the closing resistor 6 shown in FIG. 6 and the NGR shown in FIG. 7. In FIGS. 6 and 7, 8 is a capacitor, 9 is a shutoff part, IO is an oil pump, 11 is an opening/closing operation piston, and 12 is an air tank.

13 is a pilot valve, 14 is a solenoid valve for opening, 17 is a bushing, 18 is a tank, and 19 is a ground terminal.

FIGS. 8 and 9 compare the closing resistor and NGR of a circuit breaker using the oxide resistor of the present invention and a conventional resistor.

〔Effect of the invention〕

As explained above, according to the present invention, the switching surge withstand capacity is approximately 1.7 times greater than that of conventional resistors (carbon-dispersed resistors), the linearity of voltage-current characteristics is excellent, and the temperature coefficient of resistance is positive. Moreover, an excellent oxidized material resistor can be obtained which is small in size and has a small change in resistance after heat treatment at 500C. From this, the area occupied by the resistor of conventional circuit breakers (2
73) can be reduced to about 1/2.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the microstructure of an oxide resistor according to an example of the present invention, Fig. 2 is a relationship between the specific gravity of the oxide resistor and the switching surge withstand capacity of the circuit breaker, and Fig. 3 is a diagram of the oxide resistor. 4 and 5 are explanatory diagrams of an oxide resistor according to an embodiment of the present invention. FIGS. 6 and 7 are explanatory diagrams of an embodiment to which the present invention is applied. 8 and 9 are comparative explanatory diagrams between the present invention and the prior art. DESCRIPTION OF SYMBOLS 1...Sintered compact, 2...Electrode, 3...Membrane, 4...
internal cylinder.

Claims (1)

[Claims] 1. Oxide particles consisting of a compound produced by the reaction of crystal grains made of zinc oxide, a metal or metalloid element other than zinc oxide, and zinc oxide, and an oxide of a metal or metalloid element other than zinc oxide A composite oxide resistor composed of particles contains zinc oxide as a main component, silicon and magnesium as subcomponents, and further contains at least one or more elements selected from lithium, copper, and silver, respectively. Li_2
0.01 of the total in terms of O, Cu_2O, Ag_2O
An oxide resistor characterized by containing from mol % to 10 mol %.