JP2559838B2 - Voltage nonlinear resistor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a voltage non-linear resistor containing zinc oxide as a main component, and more particularly to a voltage non-linear resistor having stable electrical characteristics and lightning surge withstand characteristics. .

(Prior art) Bi ₂ O ₃ , Sb ₂ O ₃ , SiO ₂ and Co ₂ containing zinc oxide as a main component have been conventionally used.
It is widely known that a resistor containing a small amount of additives such as O ₃ and MnO ₂ exhibits excellent voltage non-linearity, and it is used in a lightning arrester or the like by utilizing the property.

In this voltage non-linear resistor, when a surge current such as lightning is applied to the element, discharge may occur mainly along the side surface of the element, so-called creeping discharge, and the element may be destroyed. It is common to provide a lateral high-resistance layer made of, for example, a Bi-Sb-Si-based compound or a Bi-Sb-Si-Zn-based compound containing a zinc silicate phase.

(Problems to be Solved by the Invention) Among these, since the bismuth oxide phase affects the hygroscopicity, there is a problem that the hygroscopicity of the side surface high resistance layer is lowered depending on the state of the crystal phase of bismuth oxide. As a result, creeping discharge in the side surface high resistance layer cannot be prevented at a high level, and there is a problem that the lightning surge resistance of the resistor is reduced.

An object of the present invention is to solve the above-mentioned problems and to provide a voltage non-linear resistor which can improve the moisture resistance of the lateral high-resistance layer and can also improve the lightning surge withstand capability of the resistor.

(Means for Solving the Problem) The voltage nonlinear resistor of the present invention has at least a bismuth oxide phase and a zinc silicate on a side surface of a sintered body containing zinc oxide as a main component and at least one metal oxide. A voltage non-linear resistor having a side surface high resistance layer containing a phase is characterized in that the bismuth oxide phase present in the side surface high resistance layer contains 30% by weight or more of the γ phase.

(Operation) In the above structure, if the bismuth oxide phase present in the lateral high-resistance layer contains 30% by weight (hereinafter simply referred to as%) or more of the γ phase, the denseness of the lateral high-resistance layer is improved. As a result, it has been found that the resistance to lightning surge of the resistor is also improved because the moisture resistance is also improved.

Further, it is preferable that the zinc silicate phase present in the side surface high resistance layer is a continuous layer because it further improves the moisture resistance and the lightning surge resistance of the resistor, and at the same time, the side surface high resistance layer has a spinel crystal phase. It is preferable to contain the above because it prevents unnecessary diffusion and evaporation of bismuth oxide from the resistor and forms a uniform side surface high resistance layer.

In order to obtain the lateral high resistance layer containing the γ phase, amorphous silica having an average particle size of 10 μm or less, preferably 3 μm or less is used as the Si component in the mixture forming the high resistance layer, and Particle size is 10μm or less, preferably 5μ
It is necessary to use Bi ₂ O _{3 of} m or less and, if necessary, Sb ₂ O ₃ having an average particle size of 10 μm or less, preferably 3 μm or less. In addition, a side surface high resistance layer is provided on the side surface of the resistor at a coating amount of 5.5 to 33.0 mg / cm ² , and after cooling the side surface high resistance layer at 1000 to 1300 ° C, a cooling rate of 600 to 900 ° C is set to 10 to 60 ° C. ° C / h
r is preferable.

The method for producing the amorphous silica to be used is not particularly limited, but it is preferable to use the one obtained from the metathesis reaction of sodium silicate or the one obtained by the thermal decomposition of silicon tetrachloride. Also, SiO ₂ is preferably 95% or more.

(Example) In order 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 Bi ₂ O ₃ , Co ₃ O ₄ , MnO ₂ adjusted to a predetermined particle size were prepared. , Sb ₂ O ₃ ,, Cr ₂ O ₃ ,, SiO ₂ , NiO
And the like. At this time, a predetermined amount of polyvinyl alcohol aqueous solution or the like is added to these raw material powders, preferably mixed by a disper mill, and then preferably granulated by a spray dryer to obtain a granulated product. After granulation, it is molded into a predetermined shape under a molding pressure of 800 to 1000 kg / cm ² . The temperature rise / fall rate of the molded body is 50-70 ℃ / h
Preliminary firing is performed under the conditions of r = 800 to 1000 ° C. and holding time of 1 to 5 hours.

Before calcination, the molded body should be heated / cooled at a rate of 10-100 ° C / hr.
It is preferable to hold at 400 to 600 ° C. for 1 to 10 hours to scatter and remove the organic binder and the like. The element body of the present invention refers to a molded body and a degreased body that has been heat-treated under the above conditions.

Next, a side surface high resistance layer is formed on the side surface of the calcined body that has been calcined. In the present invention, a mixture paste for side surface high resistance layer is prepared by adding ethyl cellulose, butyl carbitol, n-butyl acetate or the like as an organic binder to a predetermined amount of a bismuth compound, an antimony compound, a silicon compound or the like adjusted to a predetermined particle size. Apply to the side of the calcined body to a thickness of ~ 300 μm. At this time, in the present invention, the silicon compound has an average particle size of 10 μm.
The following amorphous silica is used. The mixture paste may be applied to the element body. Next, set this temperature
40-60 ° C / hr, 1000-1300 ° C, preferably 1100-1250 ° C,
After the main calcination under the condition of 3 to 7 hours, it is preferable to cool at 600 to 900 ° C at a cooling rate of 10 to 60 ° C / hr. A glass paste prepared by adding ethyl cellulose, butyl carbitol, n-butyl acetate, etc. as an organic binder to crow powder is applied on the above-mentioned lateral high resistance layer to a thickness of 100 to 300 μm, and the temperature rising / falling rate is 100 in air. ~ 200 ℃ / hr, 400-600 ℃,
The glass layer is preferably formed by heat treatment under the condition of holding time of 0.5 to 2 hours.

After that, the voltage non-linear resistor obtained was
Polishing is performed with water, preferably oil, using a polishing agent corresponding to # 400 to 2000 such as ₂ O ₃ and diamond. Next, after cleaning the polished surface, an electrode made of, for example, aluminum is provided on both polished surfaces by, for example, thermal spraying to obtain a voltage non-linear resistor.

Hereinafter, the results of actually measuring various characteristics of the voltage nonlinear resistor within and outside the range of the present invention will be described.

Example In order to investigate the effect of the γ-phase content in the lateral high-resistance layer in a voltage nonlinear resistor with a diameter of 47 mm and a thickness of 22.5 mm prepared by the method described above, the composition of the element body was Bi ₂ O ₃ 1.0 Mol%,
Co ₃ O ₄ 0.7 mol%, MnO ₂ 0.5 mol%, Sb ₂ O ₃ 1.0 mol%, Cr ₂
O ₃ 0.5 mol%, NiO 0.5 mol%, Al ₂ O ₃ 0.005 mol%, SiO ₂ 2
Mol% and the balance ZnO, the mixture for the side surface high resistance layer is amorphous silica having an average particle size of 3 μm, the average particle size is 5 μm.
m bismuth oxide and an average particle size of 3 μm antimony oxide
SiO ₂ 80 to 90 mol%, Bi ₂ O ₃ 2 to 7 mol%, Sb ₂ O ₃ balance was adjusted to a composition, and 30% or more of the bismuth oxide phase was the γ phase. 9 and a comparative example sample in which the γ phase is less than 30%
No. 1 to 5 were prepared. For each prepared sample, the γ-phase content of bismuth oxide, the state of the zinc silicate layer, the humidity resistance and the lightning surge resistance were measured. The results are shown in Table 1.

In Table 1, the γ-phase content of bismuth oxide was determined by an internal standard method by X-ray diffraction (using CaCO ₃ as an internal standard). The state of the zinc silicate layer was obtained by cutting out a test piece including the lateral high-resistance layer from the sample and observing it with a microscope. Furthermore, the moisture resistance of the high-resistance layer on the side surface was measured by observing the moisture absorption state after immersing the element in the fluorescent flaw detection liquid at a pressure of 200 kg / cm ² for 24 hours. The sample with a small amount of is shown as Δ, and the sample with the entire blur is shown as ×. Furthermore, the lightning surge resistance is 100KA, 110KA, 120K.
After the pulse currents of A and 130 KA were applied twice with a current waveform of 4/10 μS, those which were not destroyed were indicated by ◯, and those which were destroyed were indicated by ×.

From the results shown in Table 1, in the resistor of the present invention in which the bismuth oxide phase in the side surface high resistance layer contains 30% or more of the γ phase, the γ phase is
The resistance of the lateral high-resistance layer was good and the resistance to lightning surge of the resistor was good as compared with the resistor of less than 30% in the comparative example. Further, among the present invention, the test No. 1, in which the zinc silicate layer is continuous.
It was also found that Nos. 3,6 to 9 had better lightning surge withstanding capability than the discontinuous test Nos. 2,4,5.

(Effects of the Invention) As is apparent from the above description, according to the voltage nonlinear resistor of the present invention, the bismuth oxide phase in the lateral high-resistance layer has a resistance of 30%.
% Of the γ phase, the side surface high resistance layer has good moisture resistance, and the lightning surge resistance of the resistor can be improved.

Claims (3)

(57) [Claims] 1. A voltage non-linear resistor having a side surface high resistance layer containing at least a bismuth oxide phase and a zinc silicate phase on a side surface of a sintered body containing zinc oxide as a main component and at least one kind of metal oxide. In the non-linear voltage resistor, the bismuth oxide phase present in the side surface high resistance layer contains 30 wt% or more of the γ phase. 2. The voltage nonlinear resistor according to claim 1, wherein the zinc silicate particles forming the zinc silicate phase in the side surface high resistance layer are continuous. 3. The voltage non-linear resistor according to claim 1, wherein the lateral high resistance layer contains a spinel phase.