JP2002343610A - Voltage non-linear resistor and arrester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voltage non-linear resistor that can suppress increase in leakage current during charging and is superior in changing life time characteristics, and to provide an arrester provided with the same. SOLUTION: This voltage non-linear resistor is made mainly of lead oxide; the bismuth oxide phase in a sintered body, such that a composition containing at least bismuth oxide and chromium oxide is sintered, contains at least chromium element; the mole ratio of bismuth element constituting the bismuth oxide phase to chromium element is in the range of 0.03 to 0.09 for chromium element with respect to 1 of bismuth element; and an arrester is provided with the voltage non-linear resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage non-linear resistor mainly composed of zinc oxide containing at least bismuth oxide and chromium oxide as additional components, and a lightning arrester equipped with the voltage non-linear resistor. .

[0002]

2. Description of the Related Art A voltage non-linear resistor mainly composed of zinc oxide used for a lightning arrester or the like includes bismuth oxide, which is said to be essential for the expression of voltage non-linearity, in addition to zinc oxide which is a main component. And a sintered body obtained by mixing a composition to which an additive effective for improving electric characteristics is added, and passing through the steps of granulation, molding, and sintering. As shown in FIG. 3, in such a voltage nonlinear resistor, a sintered body is provided with a side surface high resistance layer and a pair of electrodes made of metal aluminum or the like.

FIG. 4 is a schematic view showing a fine structure of a part of a general crystal structure of a voltage non-linear resistor, wherein 1 is Zn ₇ Sb ₂ O ₁₂ particles containing zinc and antimony as main components, and 2 is oxidized. Zinc particles, 3 are bismuth oxide phases, and 4 are twin boundaries within zinc oxide crystal particles. That is, zinc oxide particles 2 are included in Zn ₇ Sb ₂ O ₁₂ particles containing zinc and antimony as main components.
There are two kinds of existing states, one existing around the triple point (multiple point) of the zinc oxide particles and one existing near the triple point (multiple point) of the zinc oxide particles. Some are present at the border.

In a voltage non-linear resistor, particles containing zinc oxide as a main component themselves simply act as a resistor, and a boundary portion between zinc oxide particles and zinc oxide particles has a very high resistance, and at the same time, the resistance is low. It is well known that the voltage-current characteristics of a voltage non-linear resistor exhibit non-linearity because such a voltage does not have linearity, that is, is non-linear.

FIG. 5 is a characteristic diagram showing a voltage-current characteristic (non-linear characteristic) of a general voltage non-linear resistor having the above-mentioned fine structure. Excellent The zinc oxide-based voltage nonlinear resistor having the protection performance, in FIG. 5, the ratio of the voltage V _L of the voltage V _H and the small-current region L in the large current region H V _H / V _L (limit voltage ratio : Flatness) is small. When discussing the improvement of the limiting voltage ratio, factors that determine the limiting voltage ratio in the large current region and the limiting voltage ratio in the small current region are different, so it is necessary to separately discuss each factor. Therefore, the limit voltage ratio V _H / V _L will be calculated using the voltage V _S at S in FIG. 5 and the large current range voltage ratio V _H / V _S and the small current range voltage ratio V _S /
_VL will be discussed separately.

[0006] large current area voltage ratio V _H / V _S is, V _H have been said to depend electrical resistivity of the internal zinc oxide crystal grains, the V _H higher the resistivity of the internal zinc oxide crystal grains is reduced V _H / V _S becomes smaller. On the other hand, it is said that the small current region voltage ratio V _S / V _L is determined by the Schottky barrier which is considered to be formed at the zinc oxide crystal grain boundary, and the apparent resistivity of the zinc oxide crystal grain boundary is large. V _S / V _L becomes smaller. Therefore, the limiting voltage ratio V
It is shown that in order to improve _H / V _L , the electrical resistivity inside the zinc oxide crystal grains should be reduced and the apparent electrical resistivity at the zinc oxide crystal grain boundaries should be increased.

When the voltage applied to the voltage non-linear resistor exceeds a threshold voltage (varistor voltage), a current suddenly flows through the voltage non-linear resistor. In FIG. 5, V _S represents the varistor voltage. The V _S value is set corresponding to the power transmission lines arrester is applied, V1mA (across the inter-electrode voltage of the voltage nonlinear resistor voltage produced by 1mA energized nonlinear resistor (V)) typified by Often used as a value. Considering the size of the voltage non-linear resistor, a current value of 1 mA corresponds to a current density of about 30 to 150 μA / cm ² . The _VS value of the voltage nonlinear resistor is proportional to the thickness of the voltage nonlinear resistor.

[0008] Further, in the voltage non-linear resistor, the application life characteristic is extremely important. Particularly, a voltage non-linear resistor used recently in a lightning arrester is mainly a gapless type which is excellent in response characteristics to a surge such as an abnormal voltage, so that the voltage non-linear resistor is always in a state of being charged. Therefore, a small amount of current flows through the voltage nonlinear resistor. This current is called a leak current. If the leakage current tends to increase significantly with the passage of time, the heating value of the voltage non-linear resistor increases as the leakage current increases, eventually causing thermal runaway, and the voltage non-linear resistor itself becomes There is a risk of destruction. Generally, the life of a voltage non-linear resistor is represented by the time required for the leakage current of the voltage non-linear resistor to reach a certain reference value. That is, in order to improve the life of the voltage non-linear resistor, in other words, the life characteristics of the voltage non-linear resistor, the increasing gradient of the leakage current of the voltage non-linear resistor during the application of the electric power is reduced, or the leakage current is increased with respect to time. Need to show a downward trend.

In order for the leakage current to show a decreasing tendency with respect to time, the sintered voltage non-linear resistor is heated again, that is, the bismuth oxide contained in the voltage non-linear resistor is removed by a so-called post heat treatment. It is known that it is effective to change the phase to γ-type bismuth oxide (for example, JP-B-53-021509, JP-A-52-53295, and Patent No. 1096348). The ratio of bismuth oxide contained in the voltage non-linear resistor turned into γ-type bismuth oxide is called a γ conversion ratio, and the value can be obtained from data measured by an X-ray diffractometer (XRD). No. 1869414).

When the post heat treatment is performed, the current tends to decrease with time, but the voltage ratio in the small current region increases. An increase in the small current area voltage ratio causes an increase in the initial leakage current, which may facilitate the increase of the leakage current, particularly when used at a high charging rate. According to Japanese Patent No. 1552242, a voltage non-linear resistor sintered at a high temperature of 1050 to 1300 ° C. is reheated to 500 to 700 ° C., and after holding for 1 to 2 hours, at a temperature lowering rate of 100 to 300 ° C./h. A method is disclosed in which the characteristics of the voltage non-linear resistor are prevented from deteriorating by a single post-heat treatment after sintering, which is re-cooled to room temperature.
Also, according to Japanese Patent No. 1537488, 1050 to
A voltage non-linear resistor sintered at a high temperature of 1300 ° C. is 850
Reheat to ９950 ° C., hold for 1-2 hours,
Cool to 300 ° C at 00 ° C / h, and again 500-700
C. and maintained for 1 to 2 hours.
A method is disclosed in which the characteristics of the voltage non-linear resistor are prevented from deteriorating by cooling after cooling to room temperature at a rate of 2 ° C./h, that is, two post-heat treatments after sintering.

[0011]

As described above, the conventional non-linear resistor after sintering has a remarkable increase in leakage current during the application of electric power. Although the heat treatment was an essential step, an increase in the small current range voltage ratio was unavoidable, and as disclosed in Japanese Patent No. 1537488, to prevent the small current range voltage ratio from increasing. If the post-heat treatment is performed twice, there are problems that the manufacturing process becomes complicated and the manufacturing cost is greatly increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and suppresses an increase in leakage current of a voltage non-linear resistor after sintering. The purpose is to get the body.

[0013]

According to a first aspect of the present invention, a bismuth oxide phase in a sintered body obtained by sintering a composition containing zinc oxide as a main component and at least bismuth oxide and chromium oxide contains at least chromium element. Wherein the molar ratio of the bismuth element and the chromium element constituting the bismuth oxide phase is such that the chromium element is 0.03 to 0.09 with respect to 1 bismuth element.
Voltage non-linear resistor characterized by the following range: It is. The invention according to claim 2 is that, in the raw material of the sintered body, the amount of chromium oxide added is 0.005 to 100 parts by weight of zinc oxide.
The voltage non-linear resistor according to claim 1, wherein the amount is 0.5 to 0.5 parts by weight. According to a third aspect of the present invention, there is provided a lightning arrester including the voltage non-linear resistor according to the first or second aspect, wherein a pair of electrodes are provided on a surface of the voltage non-linear resistor and the voltage non-linear resistor is provided. The lightning arrester is characterized in that a high resistance layer is provided on a side surface of the linear resistor.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The content of zinc oxide, which is the main component of the voltage nonlinear resistor according to the present invention, is determined from the viewpoint of improving the varistor voltage and the voltage nonlinearity by using the raw material of the voltage nonlinear resistor (hereinafter, referred to as the material). , Which is simply referred to as a raw material).

The bismuth oxide according to the present invention usually has an average particle diameter of 1 to 10 μm. When the compounding amount of bismuth oxide is more than 5 mol%, the non-uniform zinc oxide particles will be promoted to have a grain growth of 0.1 mol.
%, The leakage current increases (the V _L value decreases), so it is desirable to adjust the content to be 0.1 to 5 mol%, particularly 0.2 to 2 mol% in the raw material. .

Further, the voltage non-linear resistor according to the present invention has a V _S
Antimony oxide having a property to increase the value may be contained. As antimony oxide, one having an average particle diameter of 0.5 to 5 μm is usually used. The mixing amount is 5mo
If it is more than 1%, the varistor voltage becomes high, but Zn ₇ Sb ₂ O ₁₂ particles, which are a reaction product with zinc oxide, are present in large amounts. Since Zn ₇ Sb ₂ O ₁₂ particles are insulators, their presence greatly restricts the current-carrying paths inside the voltage non-linear resistor. Therefore, when an abnormal voltage is applied to the voltage non-linear resistor, destruction due to local local current concentration and heat generation easily occurs. Therefore, it is desirable to adjust the amount of antimony oxide added to the raw material so as to contain 5 mol% or less, particularly 2 mol% or less.

Further, the voltage non-linear resistor of the present invention may contain nickel oxide, cobalt oxide and manganese oxide in order to improve the voltage non-linearity, and these usually have an average particle diameter of 10 μm or less. It is desirable to use.
In order to obtain a sufficient voltage non-linearity, the amount of each of these components is determined by adding NiO, Co ₃ O ₄ , Mn
It is desirable to adjust so as to contain 0.05 mol% or more in terms of O ₂ . However, when the amount is more than 5 mol%, Zn ₇ Sb ₂ O ₁₂ , pyrochlore phase (Z
Since n ₇ Sb ₂ O ₁₂ production reaction intermediate product) increases, the energy withstand capacity tends to decrease and the voltage nonlinearity tends to decrease. Therefore, 0.05 to 5 mol% in the raw material,
In particular, it is desirable to adjust so as to contain 2 mol% or less.

Further, the voltage non-linear resistor of the present invention may contain 0.001 to 0.01 mol% of aluminum nitrate in order to reduce the electric resistance of the zinc oxide particles and improve the voltage non-linearity. . Since the ionic radius of the aluminum ion is smaller than the Zn ²⁺ ionic radius, the solid solution is dissolved in the zinc oxide particles within the allowable range of lattice distortion, and the divalent ion Zn is converted into the trivalent aluminum ion. By the substitution, the resistance inside the zinc oxide crystal particles is reduced by the electronic effect, and as a result, the large current region voltage ratio is improved. Mol% as Al ₂ O ₃ is so is the mol% of 1/2 of aluminum nitrate Al (NO _{3) 3,} as mol% of Al ₂ O ₃ 0.0005~0.0
05 mol% is required.

Further, the voltage nonlinear resistor of the present invention has a bismuth oxide phase having a lower melting point, and has improved fluidity,
In order to play a role of effectively reducing micropores existing between particles and the like, 0.01 to 0.5 mol%
May be included in the raw material.

As described above, the voltage non-linear resistor according to the present invention has a bismuth oxide phase in a sintered body obtained by sintering a composition containing zinc oxide as a main component and containing at least bismuth oxide and chromium oxide. Element, and the molar ratio of the bismuth element and the chromium element constituting the bismuth oxide phase is such that the chromium element is 0.0
It is characterized by being in the range of 3 to 0.09.

It is said that the reason why the leakage current of the voltage non-linear resistor changes during the application of electricity is that the interface state formed at the zinc oxide grain boundary changes during the application of electricity. . The presence of bismuth oxide and oxygen is involved in the formation of the interface state, and it is thought that the form of their presence greatly affects the stability of the interface state and the electrical characteristics of the voltage nonlinear resistor. .

It is known that bismuth oxide has four phase forms, α, β, γ, and δ, and the stable form changes depending on the heating and cooling temperatures and the types of coexisting elements. Conventional voltage non-linear resistors sinter at a high temperature exceeding about 1000 ° C., and then are gradually cooled, so that mainly β-type bismuth oxide is formed. However, since the leakage current of a voltage non-linear resistor having β-type bismuth oxide has a large change with time and cannot be used in many cases, post-heat treatment is performed on the sintered body and a part or all of the bismuth oxide is converted into γ-type. Phase change in many cases.

The chromium element has a function of suppressing the formation of a pyrochlore phase which is a cause of deterioration of the electrical characteristics of the voltage non-linear resistor in the temperature lowering process in the latter half of the sintering process.
It has a function of stably presenting bismuth oxide. The presence of the δ-type bismuth oxide is important for improving the charging life characteristic, in other words, for suppressing a change in leakage current at the time of charging.
However, when the sintering temperature exceeds about 1000 ° C. as in the prior art, the chromium element changes from the δ-type bismuth oxide phase to Zn ₇ Sb ₂ O
_Since δ-type bismuth oxide cannot stably exist due to the tendency to move to the ₁₂ phase, δ-type bismuth oxide changes to β-type bismuth oxide, and as a result, the voltage applied to the voltage non-linear resistor is imposed. It is considered that the leakage current change at the time becomes large. Therefore, it is desirable that the voltage nonlinear resistor of the present invention be sintered at a temperature of 1000 ° C. or less. Further, in this voltage non-linear resistor, sintering is promoted by so-called liquid phase sintering in which bismuth oxide melts during sintering to form a liquid phase. Therefore, the sintering temperature is desirably equal to or higher than the melting point of bismuth oxide.

It is considered that the change of the leakage current during the application of the electric power is caused by the change of the interface state of the zinc oxide grain boundary and the change of the potential barrier at the grain boundary. The leakage current change at the time of power application of the voltage non-linear resistor in the present invention is small,
Δ-type bismuth oxide that contributes to the formation of stable interface states is C
This is probably because the presence of the r element stabilizes and suppresses the movement of ions that cause unstable interface states.

The amount of chromium oxide to be added is 10% zinc oxide.
It is desirable that the amount is 0.005 to 0.5 part by weight based on 0 part by weight. If the amount of chromium oxide added is less than this range, a pyrochlore phase is formed, and if it is more than this range, a ZnCr ₂ O ₄ phase is formed during sintering. Worsens rapidly.

Next, the method for manufacturing the voltage non-linear resistor of the present invention comprising the above-mentioned raw materials will be specifically described. After appropriately adjusting the average particle diameter of the raw material, for example, after forming a slurry using an aqueous polyvinyl alcohol solution,
Dry and granulate using a spray drier or the like to obtain granules suitable for molding. For example, 300 to 50 in the obtained granules.
Uniaxial pressing is performed with a pressing force of about 0 kgf / cm ² (29.4 to 49.0 MPa) to produce a powder compact having a predetermined shape. In order to remove the binder (polyvinyl alcohol) from the powder compact, the powder compact is 300 to 600
After preheating at about ℃, sintering. In the embodiment, δ
At 900 ° C. so that the bismuth oxide is stably present,
In the comparative example, data obtained by measuring a sample in which β-type bismuth oxide is present, which is sintered at 1150 ° C. as in the past, is given. These are conditions for the sintering reaction to proceed uniformly and sufficiently to densify the voltage non-linear resistor, and include an X-ray diffractometer, a thermogravimetric analyzer (TG), and a thermomechanical analyzer (TM).
A) can be set.

[0027]

EXAMPLES Hereinafter, the method for manufacturing a voltage non-linear resistor according to the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Each of the examples and comparative examples includes the following basic composition and manufacturing process. The contents of bismuth oxide, antimony oxide, chromium oxide, nickel oxide, cobalt oxide, manganese oxide and boron oxide are 1.0 and 0.
4, 0.1, 0.5, 0.4, 0.5, 0.1 mol%
It was adjusted to be. Aluminum is Al (NO ₃ ) ₃
And 4 × 10 ⁻⁵ mol was added. The balance is zinc oxide. The basic composition was mixed and pulverized using a ball mill, and then dried and granulated using a spray drier. The obtained granules are uniaxially pressed at a pressure of about 400 kgf / cm ² (39.2 MPa), and have a diameter of 40 mm and a thickness of 15 mm.
mm powder compact was produced. In order to remove the binder (polyvinyl alcohol) from the obtained powder compact,
Preheating was performed at 600 ° C. for 5 hours. After that, the sintering temperature is set to 90
The test was performed at two temperatures, 0 ° C. and 1150 ° C. The sintering at 900 ° C. has a heating and cooling gradient of 50 ° C./hr,
The sintering at 50 ° C. was performed at a temperature rising and falling gradient of 75 ° C./hr, respectively. The sintering time is 10 hr and 5 hr, respectively. The sintering at 900 ° C. is performed for 1150 ° C. times in order to improve the temperature uniformity during sintering. The size of the voltage non-linear resistor after sintering was 32 mm in diameter and 10 mm in thickness due to shrinkage and densification. The shrinkage is about 17%.

Example 1 and Comparative Example 1 After sintering, the voltage non-linear resistor was sprayed with aluminum on the surface to form an electrode, and a high resistance layer for preventing flashover was formed on the side face, and the electrical characteristics were measured. . Evaluated for the small-current region voltage ratio _{(V 1mA / V 10 μ A} ), the varistor voltage (V _1mA / mm),
The three items are the large current range voltage ratio ( _{V2.5 kA} / V1 _mA ). V
_NmA represents a voltage appearing between the electrodes when a current of NmA flows through the voltage non-linear resistor. The results are shown in Table 1.

[0030]

[Table 1]

As shown in Table 1, the voltage ratio in the small current region and the voltage ratio in the large current region are as follows.
In comparison with the voltage non-linear resistor sintered at 50 ° C,
It turns out that it is excellent about 0.2 and 0.07. This can be considered to reflect the result that the scattering of bismuth oxide was suppressed by sintering at a lower temperature than usual.

Example 2 and Comparative Example 2 The samples for which the electrical characteristics were measured were further evaluated for resistance leakage current change with time when an AC voltage was applied (current application life characteristics). For the purpose of accelerating evaluation, the power application rate is 80% and the temperature is 120 ° C. The results are shown in FIG. It can be seen that the leakage current change of the sample sintered at 900 ° C. (Example 2) is smaller and more stable than that of the sample sintered at 1150 ° C. (Comparative Example 2).
The difference in the magnitude of the leakage current at the start of the measurement is due to the difference in the small current range voltage ratio between the two samples.

Example 3 and Comparative Example 3 By focusing on bismuth and chromium elements, the composition of the bismuth oxide phase present in the sintered body was determined by EPMA (Electron P).
probe Microanalysis). The results are shown in FIG. The white part in the reflected electron image in the figure is the bismuth oxide phase. It is clear that the bismuth oxide phase of the sample sintered at 900 ° C. (Example 3) contains chromium element, but the sample sintered at 1150 ° C. (Comparative Example 3)
It can be seen that no clear chromium element is present in the bismuth oxide phase of Example 1. This is because the chromium element contained in the bismuth oxide phase was almost entirely incorporated into the Zn ₇ Sb ₂ O ₁₂ particles by sintering at a high temperature of 1150 ° C. In addition, in Example 3 and Comparative Example 3, chromium elements were detected in other than the bismuth oxide phase. This is derived from the chromium element incorporated in Zn ₇ Sb ₂ O ₁₂ phase, the chromium element Zn ₇ that was also added with some in Example 3 S
It can be seen that b ₂ O ₁₂ particles are incorporated.

Example 4 Further, the compositional analysis of two different parts of the obtained bismuth oxide phase was carried out by the WDS (Wavelengt) of EPMA.
h Dispersive Spectrometer
r) Performed using the function. Table 2 shows the results of a composition analysis of five different bismuth oxide phases in the sample using EPMA.

[0035]

[Table 2]

The molar ratio between the bismuth element and the chromium element in the bismuth oxide phase contained in the sample sintered at 900 ° C. was such that the ratio of the chromium element to the bismuth element was 0.03 to 0.03.
It turns out that it is the range of 0.09. Note that the voltage non-linear resistor in this embodiment is useful for an arrester or the like.

[0037]

According to the first aspect of the present invention, a bismuth oxide phase in a sintered body obtained by sintering a composition containing zinc oxide as a main component and at least bismuth oxide and chromium oxide contains at least chromium element, Since the molar ratio of the bismuth element to the chromium element constituting the bismuth oxide phase is characterized in that the chromium element is in the range of 0.03 to 0.09 with respect to the bismuth element 1, the leakage current during power application Can be suppressed, and a voltage non-linear resistor excellent in power application life characteristics can be provided. In addition, since the voltage nonlinear resistor of the present invention can produce a sintered body without post-heat treatment,
This makes it possible to shorten the time required for manufacturing the voltage non-linear resistor, greatly reduce the use of electric power, and significantly reduce the manufacturing cost associated therewith.

The invention of claim 2 is characterized in that the amount of chromium oxide in the raw material of the sintered body is 0.005 to 0.5 parts by weight based on 100 parts by weight of zinc oxide. It is possible to suppress the formation of intermediate products such as a pyrochlore phase and a ZnCr ₂ O ₄ phase that deteriorate the electrical characteristics of the linear resistor.

According to a third aspect of the present invention, there is provided an arrester including the voltage non-linear resistor according to the first or second aspect, wherein a pair of electrodes are provided on a surface of the voltage non-linear resistor,
In addition, since a high resistance layer is provided on the side surface of the voltage non-linear resistor, a long-life lightning arrester can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a temporal change of a leakage current in an example of the present invention.

FIG. 2 shows B using EPMA in an embodiment of the present invention.
This is the result of confirming the presence of i and Cr.

FIG. 3 is a schematic diagram showing a structure of a general voltage nonlinear resistor.

FIG. 4 is a schematic view showing a fine structure of a part of a crystal structure of a general voltage nonlinear resistor.

FIG. 5 is a characteristic diagram showing a voltage-current characteristic of a general voltage nonlinear resistor.

[Explanation of symbols]

1 Zn ₇ Sb ₂ O ₁₂ particles, 2 zinc oxide particles, 3 bismuth oxide phase, 4 twin boundaries.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoaki Kato 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Akio Hori 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd. (72) Inventor Iwao Kawamata 2-3-2 Marunouchi, Chiyoda-ku, Tokyo, Japan Mitsui Electric Co., Ltd. (72) Inventor Yoshio Takada 2-3-2 Marunouchi, Chiyoda-ku, Tokyo, Mitsubishi Inside Electric Co., Ltd. (72) Inventor Hide Yamashita 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. (72) Inventor Atsushi Iga 1-1-14 Yamato, Takatsuki City, Osaka, Japan Synctopia Limited (72) Inventor Taiki Miyamoto 2-7-1, Ayumino, Izumi-shi, Osaka Inside the Osaka Prefecture National Institute of Advanced Industrial Science and Technology (72) Inventor Takashi Miyamoto Osaka Izumi City Ayumino 2-chome No. 7 No. 1 Osaka Prefectural National Institute of Advanced Industrial Science and Technology in the F-term (reference) 5E034 CA09 CB01 CC03 DA03 DB12 DC03 EA07

Claims (3)

[Claims] 1. A bismuth oxide phase in a sintered body obtained by sintering a composition containing zinc oxide as a main component and containing at least bismuth oxide and chromium oxide contains at least chromium element, and forms a bismuth oxide constituting the bismuth oxide phase. A voltage nonlinear resistor, wherein the molar ratio of the element to the chromium element is in the range of 0.03 to 0.09 for the chromium element to the bismuth element 1. 2. The amount of chromium oxide in the raw material of the sintered body is 0.005 to 0.5 with respect to 100 parts by weight of zinc oxide.
2. The voltage non-linear resistor according to claim 1, wherein the voltage is non-linear. 3. A lightning arrester comprising the voltage non-linear resistor according to claim 1 or 2, wherein a pair of electrodes are provided on a surface of the voltage non-linear resistor, and the voltage non-linear resistance is provided. A lightning arrester characterized by a high resistance layer provided on the side of the body.