JPH0223007B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a voltage nonlinear resistor made of a sintered body mainly composed of zinc oxide, which can be used for arresters, surge absorbers, etc., and a method for manufacturing the same. BACKGROUND OF THE INVENTION Zinc oxide-based voltage nonlinear resistors are manufactured using generally well-known ceramic sintering techniques.
The main component is zinc oxide (ZnO) powder, and it also contains bismuth oxide (Bi ₂ O ₃ ), antimony oxide (Sb ₂ O ₃ ), cobalt oxide (Co ₂ O ₃ ), manganese oxide (MnO ₂ ), and oxide. Chromium (Cr ₂ O ₃ ), silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), etc. are added and mixed thoroughly, followed by water and a suitable binder such as polyvinyl alcohol. is added, granulated and molded. Firing is performed at a temperature of 1000 to 1300°C using an electric furnace. For the fired resistor, a lead borosilicate glass film with a low melting point is baked on the side surface of the resistor at 400 to 900℃ for the purpose of preventing creeping discharge, and then both end faces, where electrodes will be formed, are polished to a predetermined thickness. The electrodes are formed by thermal spraying or baking to form a voltage nonlinear resistor. Furthermore, an example is known in which lead glass having a softening point of 350 to 650° C. is mixed with a refractory filler as the glass. However, the resistor obtained by this method has the following drawbacks. First, there is a drawback that when the glass is baked at a temperature of 400 to 900°C, the nonlinear coefficient of the resistor becomes smaller than before the glass is baked. Second
Due to the poor moisture resistance of the glass used in these devices, the glass may deteriorate or erode when used in high humidity or during etching treatment before forming electrodes, or may be sealed in nitrogen as in arresters. Then,
The drawback is that the glass is corroded by the nitric acid gas generated by corona discharge, reducing the creeping withstand voltage of the resistor. [Object of the Invention] The present invention has been made in view of the above, and its object is to provide a voltage nonlinear resistor with stable characteristics such as nonlinear coefficient and creepage breakdown voltage, and a method for manufacturing the same. [Summary of the Invention] To summarize the present invention, the first invention of the present invention is an invention of a voltage nonlinear resistor, which comprises a ceramic high-resistance layer on at least the side surface of a sintered body mainly composed of zinc oxide. In a voltage nonlinear resistor in which a glass layer is formed with or without intervening and electrodes are formed on both the upper and lower end surfaces of the sintered body, the glass layer contains the following components: Lithium oxide (Li ₂ O): 10 ~30 mol% Silicon oxide ( _SiO2 ): 50-70 mol% Zinc oxide (ZnO): 5-15 mol% Boron oxide _{( B2O3 )} : 0-10 mol% Aluminum oxide ( _Al2O3 ): It is characterized by being a lithium zinc silicate glass containing 0 to 5 mol%. The second invention of the present invention is an invention of a method for manufacturing an example of the voltage nonlinear resistor, which comprises forming a ceramic high resistance layer on the side surface of a sintered body mainly composed of zinc oxide, and Lithium oxide 10-30 mol%, silicon oxide 50-70 mol%, zinc oxide 5-15
A step of applying a paste consisting of a lithium zinc silicate glass component containing mol%, boron oxide 0 to 10 mol%, and aluminum oxide 0 to 5 mol% and a binder, at 950°C in an oxygen-containing gas atmosphere.
The steps of forming a glass layer by baking at a temperature lower than the firing temperature of the sintered body and 100 to 200°C higher than the softening temperature of glass, and forming electrodes on both end surfaces of the sintered body are explained above. It is characterized by including each step. FIG. 1 shows the structure of an example of the voltage nonlinear resistor of the present invention as a schematic cross-sectional view. In FIG. 1, 1 means a sintered body, 2 means a glass layer, and 3 means an electrode. Further, FIG. 2 is a graph showing the relationship between the heat treatment temperature (horizontal axis) (° C.) of the voltage nonlinear resistor and the rate of change of the nonlinear coefficient (vertical axis) (%). In FIG. 2, A is a graph in which heat treatment was performed in the air for 1 hour at each temperature, and B is a graph in which heat treatment was performed in an oxygen atmosphere for 1 hour at each temperature. As a result of various studies conducted by the inventors, (1) As shown in Fig. 2, when the resistor is heat-treated after firing,
In the temperature range of 500 to 900°C, the nonlinear coefficient of the resistor decreases, but at temperatures above 950°C, it becomes almost the same as before heat treatment, or even increases. (2) In order to improve the adhesion between the resistor and the electrode, the surface of the resistor after polishing may be etched with an acid such as hydrochloric acid or nitric acid. For this purpose, it is necessary to use a glass with good acid resistance for side coating. (3) Generally, the acid resistance of lithium silicate glass is due to the SiO ₂ in the glass.
and Li ₂ O to some extent, Li ₂ O・SiO ₂ , Li ₂ O・
It can be made larger by using glass with 2SiO ₂ crystals. If the composition of the glass is 50 to 70 mol% silicon oxide and 10 to 30 mol% lithium oxide, there will be no practical problem in corrosion resistance to the etching solution. (4) The coefficient of thermal expansion of high melting point lithium silicate glass with a baking temperature of 950°C or higher is generally larger than that of the resistor, but zinc oxide is added to the glass by 5 to 15 mol%.
It was found that the coefficient of thermal expansion becomes smaller if the added glass is used. In addition, Li ₂ O in the glass diffuses into the sintered body during baking, making the diffusion part high in resistance, increasing the adhesion between the sintered body and the glass, and reducing the creepage of the resulting voltage nonlinear resistor. It is particularly effective in increasing the withstand voltage. Furthermore, SiO ₂ in the glass increases the moisture resistance and acid resistance of the glass, and is effective in maintaining a high creepage withstand voltage of the voltage nonlinear resistor. When heat treated at a temperature of 500 to 900℃, the
The Bi ₂ O ₃ phase undergoes a phase change, the nonlinear coefficient decreases,
It is presumed that at temperatures above the melting point of Bi ₂ O ₃ (830°C), the same phase as that after firing is formed and the nonlinear coefficient does not decrease. Furthermore, when heat treated in oxygen, a large amount of oxygen ions are adsorbed on the particle surface of the zinc oxide crystal, increasing the nonlinear coefficient. The glass baking temperature is preferably about 100 to 200°C higher than the softening temperature of the glass. That is, if the glass baking temperature is lower than this, it will not become glassy, and if it is higher than this, the glass will flow during baking, making it impossible to obtain a glass film of uniform thickness. In addition, in the resistor of the present invention, it has been mentioned that the glass has excellent acid resistance, but when the resistor is used in a nitrogen atmosphere such as in an arrester, corona is generated and generated. There is no risk of being etched by nitric acid, and the properties are stable. In the voltage nonlinear resistor of the present invention, bismuth oxide and manganese oxide are added in an amount of 0.01 to 10 mol % each to zinc oxide as the main component, and preferably 0.002 to 5 mol % each of each.
After adding mol% of ammothine oxide, cobalt oxide, chromium oxide, boron oxide, silicon oxide, aluminum oxide, etc., it is fired at 1000 to 1300℃, and acid-resistant lithium zinc silicate glass powder is applied to the side of the resistor. After heat-treating at a temperature of 950 to 1250°C to coat the resistor with glass, polishing both end faces of the resistor to a predetermined thickness, preferably etching the polished surfaces with hydrochloric acid or nitric acid, and then forming electrodes. can be obtained.
Here, if the glass is coated after the electrode is formed, the electrode will be oxidized during glass baking, which is not good. Furthermore, if the glass baking temperature exceeds 1300° C., the glass and the sintered body will react violently, and a large amount of glass components will diffuse into the sintered body, which will impair the characteristics of the resistor, which is not preferable. The following points are important regarding the glass used in the present invention. That is, firstly, in order not to deteriorate the original characteristics of the resistor, it is necessary to bake the glass on the resistor at a high temperature of 950 to 1250 degrees Celsius, and it must be a high melting point glass. Secondly, in order to improve the adhesion between the electrode and the resistor, it is desirable that the glass can be etched using hydrochloric acid, nitric acid, etc. after baking the resistor. Acid-resistant glass is required to prevent surface creepage of a resistor sealed in a nitrogen atmosphere. Furthermore, in order to prevent creepage, the thickness of the glass film must be approximately 30 μm or more, and it is desirable that the coefficients of thermal expansion of the resistor and the glass be similar. The thermal expansion coefficient of zinc oxide resistor is 50~
Since it is 70×10 ^-7 /℃, the coefficient of thermal expansion of glass is
A range of 40 to 80×10 ⁻⁷ /°C is particularly preferred. If there is a large difference in the coefficient of thermal expansion, cracks will occur during cooling during glass baking, making it impossible to achieve sufficient stability when applying a large current or prevent creepage. In order to prevent these cracks, it is particularly desirable that the glass be crystallized glass. The main composition of the lithium zinc silicate glass of the present invention is 10 to 30 mol% of lithium oxide, 50 to 70 mol% of silicon oxide, 5 to 15 mol% of zinc oxide,
0-10 mol% boron oxide, 0 aluminum oxide
It is desirable that the content be in the range of ~5 mol%. If the amount of zinc oxide is less than this range, the coefficient of thermal expansion of the glass will be greater than 80×10 ^-7 /°C. Furthermore, if the amount of zinc oxide is higher than this range, the coefficient of thermal expansion will be 40×10 ^-7 /°C.
become smaller. On the other hand, boron oxide reduces the viscosity of the glass and improves the wettability of the resistor. However, if the amount of boron oxide is too large, the moisture resistance will deteriorate, and a particularly preferable composition is 3 to 10 mol%. Addition of aluminum oxide is effective in preventing phase separation of glass. It is particularly desirable for the glass of the present invention to contain 10 to 30 mol% of lithium oxide and 50 to 70 mol% of silicon oxide in order to improve the acid resistance and mechanical strength of the glass. Glass containing lithium oxide and silicon oxide turns into crystallized glass during baking, increases the strength of the glass layer, prevents cracks in the glass layer, and improves the durability of the voltage nonlinear resistor. Even if lithium oxide and silicon oxide are more than the above range,
At least this effect will not be sufficient. Therefore, the main composition of the lithium zinc silicate glass of the present invention is 10 to 20 mol% of lithium oxide, 60 to 70 mol% of silicon oxide, and 5 to 5 mol% of zinc oxide.
Particularly desirable ranges are from 6 to 10 mol% of boron oxide and 2 to 4 mol% of aluminum oxide. FIG. 3 is a schematic cross-sectional view showing the structure of an example of the voltage nonlinear resistor of the present invention. In Figure 3,
Reference numerals 1 to 3 have the same meanings as in FIG. 1, and 4 means a ceramic high resistance layer. As shown in Figure 3, Zn ₇ Sb ₂ O ₁₂ and Zn ₂ SiO ₄ are present at the interface between the glass layer and the sintered body.
A high-resistance oxide layer made of, for example, may be provided to further improve the adhesion between the glass layer and the sintered body. Furthermore, it goes without saying that the glass layer may cover part of the upper and lower surfaces where the electrodes are provided. [Examples of the Invention] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 7630 g of zinc oxide as the main component, 325 g of bismuth oxide (Bi ₂ O ₃ ), 166 g of cobalt oxide (Co ₂ O ₃ ), and 57 g of manganese oxide (MnO) as additives.
g, ammothine oxide (Sb ₂ O ₃ ) 292 g, chromium oxide (Cr ₂ O ₃ ) 76 g, nickel oxide (NiO) 75 g,
Silicon oxide (SiO ₂ ) 90g, boron oxide (B ₂ O ₃ )
30g, aluminum nitrate {Al(NO ₃ ) ₂・9H ₂ O}
Weigh 1.5g accurately and wet mix in a ball mill for 12 hours. After drying, the mixed powder is granulated into 20mmφ×
Form into 10mm. The molded body was fired at 1250° C. for 3 hours in the atmosphere. Separately, powder of Pyroceram 9606 (Li ₂ O-SiO ₂ glass, manufactured by Corning, USA), which is a high-melting point crystallized glass and has good acid resistance, was suspended in an ethyl cellulose/trichloroethylene solution, and this was fired. The coating was applied by brush painting or dipping to a thickness of 50 to 300 μm. 1050 in the atmosphere
Heat treated at ℃ for 30 minutes. The rate of temperature rise and fall at this time was 30°C/hour. Both end faces of the glass-coated resistor were polished approximately 0.5 mm each using a Lap Master.
Washed. The cleaned resistor was used to form an Al sprayed electrode. This invention and the conventional product (SiO ₂ −B ₂ O ₃ −PbO
Table 1 shows a comparison of the nonlinear coefficients with that of glass (based on glass, baked at a low temperature of 650°C).

[Table] It can be seen that the product of the present invention has an extremely large nonlinear coefficient and is superior to the conventional product. Furthermore, the nonlinear coefficient of an element made of Pyroceram 9606 glass baked in an oxygen atmosphere using the same method was 90 to 100. Example 2 As in Example 1, 830 g of zinc oxide (ZnO), 30.5 g of bismuth oxide (Bi ₂ O ₃ ), 16.5 g of cobalt oxide (Co ₂ O ₃ ), 57 g of manganese carbonate (MnCO ₃ ),
Chromium oxide (Cr ₂ O ₃ ) 76 g, antimony oxide (Sb ₂ O ₃ ) 58.3 g, silicon oxide (SiO ₂ ) 10 g, boron oxide (B ₂ O ₃ ) 5 g, aluminum nitrate {Al
(NO ₃ ) ₃・9H ₂ O}0.06 g was wet mixed in a ball mill for 15 hours. After drying, the mixed powder is granulated into 20mm particles.
It was molded into a size of φ x 8 mm and fired at 1300°C for 2 hours in the air. The fired resistor was the Pyroceram of Example 1.
9606 glass paste was applied to a thickness of 100 to 200 μm and heat treated at 1000° C. for 1 hour in the air. Both end faces of the glass-coated resistor were cleaned using a Lapmaster.
Polish and clean in 0.5mm increments. In one case, an Al sprayed electrode was directly formed on the resistor after polishing and cleaning. On the other hand, polish and wash the low antibody with hydrochloric acid: water =
After etching the polished surface by immersing it in a 2:5 etching solution for 5 minutes, an Al sprayed electrode is formed. Table 2 shows a comparison between the two.

[Table] It can be seen that the etched product has a larger nonlinear coefficient than the untreated product, has a smaller rate of voltage change due to energization, and has superior rectangular wave resistance with no sparks generated near the electrode end. Example 3 Zinc oxide (ZnO) 100 as in Examples 1 and 2
Kg, Bismuth oxide (Bi ₂ O ₃ ) 4.23Kg, Cobalt oxide (Co ₂ O ₃ ) 2.15Kg, Manganese carbonate (MnCO ₃ )
0.74Kg, ammothine oxide (Sb ₂ O ₃ ) 3.78Kg, chromium oxide (Cr ₂ O ₃ ) 0.98Kg, nickel oxide (NiO ₂ )
0.97Kg, silicon oxide (SiO ₃ ) 0.78Kg, boron oxide
0.056Kg, aluminum nitrate {Al(NO ₃ ) ₃・9H ₂ O}
Mix 0.009Kg in a ball mill for 25 hours. After drying, the mixed powder is granulated and shaped into a size of 20 mmφ x 10 mm.
The molded body was then coated with a paste containing SiO ₂ --Sb ₂ O ₃ --Bi ₂ O ₃ and then fired at 1250° C. for 4 hours to produce a ceramic high-resistance layer. For the fired resistor, a paste was prepared in the same manner as in Examples 1 and 2 using glass obtained by changing the composition ratio of the lithium zinc silicate glass shown in Table 3.
It was coated to a thickness of ~200 μm and baked in air at 1000-1050°C for 1 hour.

[Table] Polish both ends of the glass-coated resistor by approximately 0.5 mm using a Lap Master. The polished resistor was immersed in an etching solution consisting of hydrochloric acid: nitric acid: water = 1:3:5 for 3 minutes to etch the polished surface.
An Al sprayed electrode was formed. As shown in Figure 3, the voltage nonlinear resistor obtained in this way has a ceramic high resistance layer made of Zn ₇ Sb ₂ O ₁₂ and Zn ₂ SiO ₄ on the side surface of the resistor, and a resistor with a glass film formed thereon. You get a body. First, Table 4 shows the acid resistance of glasses obtained by varying the composition ratio of lithium zinc silicate glasses.

【table】

[Table] *1: Glass composition is according to Table 3.
*2: Processing time: 5 hours The acid resistance of glass varies depending on the blending ratio of lithium oxide and silicon oxide in the glass composition, and the etching rate with respect to acids for glasses with composition numbers 3 to 5, which have a particularly desirable composition range of the present invention, is different from that of other glasses. It is 1/2 to 1/8 of glass. Next, Table 5 shows the rectangular wave tolerance (waveform: 2 mS).

[Table] *1: Glass composition is according to Table 3.
From Table 5, glass composition number 4 is the best, followed by numbers 3, 5, 6, 7, 2, and 1, in that order. That is, in a glass containing 10 to 30 mol% of lithium oxide and other than 50 to 70 mol% of silicon oxide, the acid resistance of the glass is poor, and the rectangular wave resistance is about 1/2 of that when using the glass of the present invention. Example 4 The raw material powder containing zinc oxide as the main component obtained in Example 3 was molded into a size of 20 mmφ x 8 mm, and was fired at 1280° C. for 3 hours. The fired resistor was prepared using the third method of Example 3.
Examples 1 and 2 of glass paste with the composition shown in the table
And apply it to a thickness of 100 to 200 μm in the same way as in 3.
Heat treatment was performed in the air at a temperature of 1000-1050°C for 1 hour. The rate of temperature rise and fall in this heat treatment is 25°C/hour. Glass-coated resistor has both end faces 0.5mm
Polish one by one. The polished resistor was immersed in an etching solution of nitric acid:hydrochloric acid:water=1:4:5 for 5 minutes to etch the polished surface, and then an Al sprayed electrode was formed.
The resistor thus obtained was sealed in a nitrogen atmosphere and changes in characteristics were examined before and after corona discharge. The characteristics before and after corona discharge for 1 hour are as follows.
It becomes a table.

[Table] *1: Glass composition is according to Table 3.
*2: Corona discharge time is 1 hour.
When glasses Nos. 3, 4, and 5 having the glass composition of the present invention are used, the impulse withstand capacity (waveform: 4×10 μS) remains almost unchanged after the corona discharge test.
On the other hand, for glasses with numbers 1, 2, 6, and 7, which have slightly lower acid resistance, the impulse withstand capacity is lower before and after corona discharge.
It has decreased by 20-35%. This is thought to be because the resistor was sealed in a nitrogen atmosphere and a corona discharge was caused, so a small amount of water in the atmosphere reacted with the nitrogen to produce nitric acid, and this nitric acid changed the quality of the glass film and caused it to deteriorate. . Example 5 Using the raw material powder containing zinc oxide as the main component obtained in Example 3, it was molded into a size of 56 mmφ x 24 mm, and fired at 1250° C. for 5 hours. A paste made of glass having the composition shown in Table 7 was applied to the fired resistor to a thickness of 100 to 200 μm in the same manner as in Examples 1, 2, 3, and 4, and the paste was heated at 800 to 1350°C for 1 hour. Baked in air. The rate of temperature rise and fall at this time was 40°C/hour. A glass-coated resistor has both end faces
Polished in 0.5mm increments. The polished resistor was immersed in an etching solution of nitric acid:hydrochloric acid:water=1:4:3 for 5 minutes to etch the polished surface, and then an Al sprayed electrode was formed. Presence or absence of cracks in the glass film of the device thus obtained, nonlinear coefficient at current of 10 μA to 1 mA, initial impulse withstand capacity, impulse withstand capacity after corona discharge test, impulse after being left in boiling water for 10 hours. Withstands 1000 thermal cycles of -40°C and 150°C
The impulse withstand capacity after the test is shown in Table 7.

【table】

[Table] Impulse withstand capacity of arrester elements
80KA or more is required for up to 288KV system, and 100KA or more is required for 420KV system or above. As seen in Table 7, samples numbered 3, 4, 5, and 13 coated with glass within the particularly desirable composition range of the present invention had no cracks in the coated glass film, had a large nonlinear coefficient, and had a high impulse response. It has a withstand capacity of 100KA or more after corona discharge tests, boiling tests, and thermal cycle tests, and can be used as an arrester element for 420KV systems or above. As is clear from Table 7, when the zinc oxide content is less than 5 mol% (numbers 8 and 9) and the samples containing more than 15 mol% (numbers 10 and 11), the coefficient of thermal expansion is the same as that of the resistor coated. Coefficient 50~70×
10 ^-7 , a difference occurs and minute cracks occur in the coated glass film. In addition, the water resistance and oxidation resistance of the glass deteriorated in samples containing more than 10 mol% of boron oxide (numbers 14 and 15), and the impulse resistance after the boiling test and the impulse resistance after the corona discharge test were lower than those of other samples (numbers 14 and 15). The deterioration is large compared to numbers 3, 4, 5, and 13). In addition, samples with too little boron oxide (no.
12), the softening temperature of the glass increases, and the glass baking temperature accordingly increases to 1350°C, which tends to worsen the nonlinear coefficient. Comparative Example 1 In the same manner as in Example 5, the raw material powder containing zinc oxide as the main component obtained in Example 3 was molded into a size of 56 mmφ x 24 mm, and fired at 1250° C. for 5 hours. The fired resistor contains a paste containing only Li ₂ O and a composition of 30 mol % Li ₂ O ^- 25 mol % Al ₂ O ₃ ^- 30 without adding SiO ₂ .
A paste was prepared using mol % ZnO ^- 15 mol % B ₂ O ₃ glass, and each paste was applied to a thickness of 100 to 200 μm and baked at 1050° C. in the atmosphere for 1 hour. The rate of temperature rise and fall at this time was 40°C/hour. Both end faces of the glass-coated resistor were polished by 0.5 mm. The polished resistor was prepared using nitric acid:hydrochloric acid:water=1:
After etching the polished surface by immersing it in a 4:3 etching solution for 5 minutes, an Al sprayed electrode was formed. Whether or not the glass film of the device obtained in this way is prone to cracking.
None, nonlinear coefficient at current 10 μA to 1 mA, initial impulse withstand capacity, impulse withstand capacity after corona discharge test, impulse withstand capacity after being left in boiling water for 10 hours, impulse withstand capacity after 1000 thermal cycles at -40°C and 150°C. As shown in Table 8. In addition, _an attempt was made to vitrify a _Li2O - _SiO2 - _B2O3 - _Al2O3 system without adding ZnO, _but it did not become glassy.

【table】

〔Effect of the invention〕

The voltage nonlinear resistor of the present invention has extremely significant effects such as an extremely large nonlinear coefficient, a small rate of change in voltage due to energization, excellent rectangular wave resistance, and good acid resistance.

[Brief explanation of drawings]

1 and 3 are schematic cross-sectional views showing the structure of an example of the voltage nonlinear resistor of the present invention, and FIG. 2 shows the relationship between the heat treatment temperature and the rate of change of the nonlinear coefficient of the voltage nonlinear resistor. This is a graph showing. 1: Sintered body, 2: Glass layer, 3: Electrode, 4: Ceramic high resistance layer.

Claims (1)

[Claims] 1. A glass layer is formed on at least the side surface of a sintered body containing zinc oxide as a main component, with or without a ceramic high-resistance layer, and electrodes are formed on both the upper and lower end surfaces of the sintered body. In the voltage nonlinear resistor, the glass layer has the following components: Lithium oxide ( _Li2O ): 10 to 30 mol% Silicon oxide ( _SiO2 ): 50 to 70 mol% Zinc oxide (ZnO): 5 to 15 A voltage nonlinear resistor characterized by being a lithium zinc silicate glass containing mol% boron oxide (B ₂ O ₃ ): 0 to 10 mol% and aluminum oxide (Al ₂ O ₃ ): 0 to 5 mol%. . 2. The voltage nonlinear resistor according to claim 1, wherein the glass layer is made of crystallized glass. 3. The voltage nonlinear resistor according to claim 1 or 2, wherein the glass is a high melting point glass having a firing temperature between 950°C and the firing temperature of the sintered body. 4 A ceramic high-resistance layer is formed on the side surface of a sintered body containing zinc oxide as a main component, and 10 to 30 mol% of lithium oxide, 50 to 70 mol% of silicon oxide,
Step of applying a paste consisting of a lithium zinc silicate glass component containing 5 to 15 mol% of zinc oxide, 0 to 10 mol% of boron oxide, and 0 to 5 mol% of aluminum oxide and a binder, in an oxygen-containing gas atmosphere at 950°C or higher, lower than the firing temperature of the sintered body, and 100 to 200°C lower than the softening temperature of glass.
A method for manufacturing a voltage nonlinear resistor, comprising the steps of forming a glass layer by baking at a high temperature, and forming electrodes on both end faces of the sintered body. 5. The method of manufacturing a voltage non-linear resistor according to claim 4, wherein the step of forming the electrodes includes etching both end surfaces of the sintered body with acid, and then forming the electrodes.