A surge arrester resistor disc and a preparation method thereof

Abstract

The application discloses a resistance disc for lightning arrester and a preparation method thereof. The resistance disc is prepared from the following components in parts by weight: modified zinc oxide 80-95 parts, bismuth oxide 3-6 parts, antimony oxide 1-4 parts, cobalt oxide 1-4 parts, nickel oxide 0.6-1.2 parts, manganese oxide 0.6-1.2 parts, chromium oxide 0.4-1.0 parts, aluminum oxide 0.2-0.6 parts and lead-free glass powder 1-4 parts. The microstructure and macroscopic performance of the material are significantly improved through two-step functional modification of the modified zinc oxide, so that the resistance disc has excellent nonlinear coefficient, low leakage current and high energy absorption capacity. The overall technical scheme not only improves the protection performance and service life of the lightning arrester, but also realizes lead-free environmental protection and energy saving and consumption reduction, thereby providing reliable guarantee for safe and stable operation of the power system.

Description

Technical Field

[0001] This invention relates to the field of surge arrester technology, and specifically to a surge arrester resistor element and its preparation method. Background Technology

[0002] Surge arresters are crucial overvoltage protection devices in power systems, effectively limiting the impact of lightning and switching overvoltages on electrical equipment and ensuring the safe and stable operation of the power system. Zinc oxide varistors, as the core component of surge arresters, directly determine the protective effect and service life of the arrester. The resistive element, as the basic unit of the zinc oxide varistor, exhibits a high impedance state under normal operating voltage. When subjected to overvoltage impulses, it rapidly transitions to a low impedance state, achieving effective protection of electrical equipment through its nonlinear volt-ampere characteristics.

[0003] Traditional zinc oxide varistors primarily use zinc oxide as the base material, combined with various metal oxide additives such as bismuth oxide, antimony oxide, and cobalt oxide. Zinc oxide provides the foundation for the varistor's properties, bismuth oxide acts as a flux to form the grain boundary phase, antimony oxide is used to adjust resistivity, and transition metal oxides such as cobalt oxide improve sintering performance and electrical properties.

[0004] CN105118591A discloses a resistor valve plate for a surge arrester, the material composition of which, by weight, consists of the following components: 8-12 parts zinc oxide, 1-4 parts antimony oxide, 2-4 parts aluminum oxide, 5-8 parts chromium oxide, 3-6 parts iron oxide, 4-7 parts cobalt oxide, 0.5-1.1 parts manganese dioxide, and 3-8 parts bismuth oxide.

[0005] However, existing technologies have many shortcomings: First, traditional zinc oxide powder is prone to agglomeration during ball milling and sintering, resulting in uneven microstructure and affecting the consistency and stability of the resistor sheet; second, zinc oxide has limited compatibility with other additives and is prone to phase separation during high-temperature sintering, affecting the optimization of grain boundary characteristics; third, traditional formulations often use lead-containing glass powder as a flux, posing an environmental pollution risk and failing to meet green manufacturing requirements; in addition, existing resistor sheets are prone to aging during long-term operation, manifested as increased leakage current and varistor voltage drift, affecting the protection performance and service life of the surge arrester.

[0006] As power systems evolve towards higher voltage and larger capacity, higher technical requirements are being placed on surge arrester resistors, including superior nonlinear characteristics, lower leakage current, stronger energy absorption capacity, longer service life, and environmental performance. Therefore, there is an urgent need to develop new material modification technologies and manufacturing processes to meet the pressing demands of modern power systems for high-performance surge arrester resistors. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a resistor sheet for surge arresters and its preparation method. The present invention significantly improves the microstructure and macroscopic properties of the material through a two-step functionalization modification of modified zinc oxide, enabling the resistor sheet to possess excellent nonlinear coefficient, low leakage current and high energy absorption capacity, and achieving a synergistic improvement in varistivity, mechanical strength and long-term stability.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A surge arrester resistor element, by weight, is composed of the following components: 80-95 parts modified zinc oxide, 3-6 parts bismuth oxide, 1-4 parts antimony oxide, 1-4 parts cobalt oxide, 0.6-1.2 parts nickel oxide, 0.6-1.2 parts manganese oxide, 0.4-1.0 parts chromium oxide, 0.2-0.6 parts aluminum oxide, and 1-4 parts lead-free glass powder.

[0009] Preferably, the particle size of bismuth oxide, antimony oxide, cobalt oxide, nickel oxide, manganese oxide, chromium oxide, and aluminum oxide powder is <1 μm, D 90 / D 10 <3; Lead-free glass powder particle size 1~5μm.

[0010] Preferably, the modified zinc oxide is prepared by the following method steps: (1) Disperse zinc oxide powder into anhydrous toluene, add p-toluenesulfonic acid, sonicate, then slowly add citric acid while stirring, stir the reaction, filter, wash and dry the product to obtain intermediate zinc oxide; Citric acid surface modification: The hydroxyl groups on the zinc oxide surface undergo esterification with the carboxyl groups of citric acid under the catalysis of p-toluenesulfonic acid, forming covalent ester bonds on the zinc oxide surface. Since citric acid contains three carboxyl groups, multi-point anchoring can be achieved, while the carboxyl groups that did not participate in esterification remain on the surface, providing functional groups for the next reaction.

[0011] Preferably, in step (1), the zinc oxide powder has a particle size of 0.1~1μm.

[0012] Preferably, in step (1), the zinc oxide powder has a particle size of 0.3~0.8μm.

[0013] Preferably, in step (1), the ratio of zinc oxide, anhydrous toluene, p-toluenesulfonic acid, and citric acid is 10g: 100~150mL: 0.1~0.3g: 1~4g.

[0014] Preferably, in step (1), the ultrasonic treatment is performed for 30 to 60 minutes, and the stirring reaction is performed under magnetic stirring at 110 to 130°C for 4 to 7 hours.

[0015] (2) Disperse the intermediate zinc oxide in anhydrous ethanol, sonicate it, and then slowly add 1-ethyl-3-methylimidazolium trifluoromethanesulfonate under nitrogen atmosphere and stir the reaction. Filter, wash and dry the product to obtain modified zinc oxide.

[0016] Electrostatic bonding of ionic liquids: The surface of citric acid-modified intermediate zinc oxide contains free carboxylic acid groups, which can partially ionize under suitable pH conditions to generate a negative charge (COO). - 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, as an ionic liquid, allows the 1-ethyl-3-methylimidazolium cation to be attracted to the vicinity of the negatively charged carboxylic acid group through electrostatic interaction, thereby achieving the orderly arrangement and stable binding of the ionic liquid on the zinc oxide surface and endowing zinc oxide with new surface properties.

[0017] Preferably, in step (2), the ratio of intermediate zinc oxide, anhydrous ethanol, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is 10g: 100~150mL: 0.6~1.2g.

[0018] Preferably, in step (2), the ultrasonic treatment is performed for 20-40 min; the stirring reaction conditions are magnetic stirring reaction at 25-40℃ for 3-6 h.

[0019] The present invention also claims a method for preparing the resistor sheet for the surge arrester, comprising the following steps: dispersing each component into a ball mill jar according to the weight parts, then adding anhydrous ethanol, and ball milling to obtain a slurry; spray granulating the slurry, then pressing and molding, pre-firing, spraying aluminum on the upper and lower surfaces, coating the sides with insulating glaze, sintering, grinding, cleaning and drying, and then spraying aluminum electrodes to obtain the resistor sheet for the surge arrester.

[0020] Preferably, the ball milling process is 2-8 hours; the pre-firing conditions are: heating to 400-900℃ at 2-5℃ / min and holding for 1-4 hours; the sintering conditions are: heating to 700-1150℃ at 5℃ / min and holding for 5-15 minutes, then cooling to 800-1100℃ at 2℃ / min and holding for 5-8 hours.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a resistor sheet for surge arresters. Modified zinc oxide, as the main phase, provides excellent varistor characteristics and nonlinear conductivity. Bismuth oxide, as a flux, effectively lowers the sintering temperature and forms a grain boundary phase, improving varistor characteristics. Antimony oxide, as a dopant, precisely adjusts resistivity and varistor voltage. Cobalt oxide promotes ceramic densification sintering and improves mechanical strength. Nickel oxide and manganese oxide synergistically improve the stability of electrical performance and varistor characteristics. Chromium oxide effectively inhibits excessive grain growth, ensuring consistent electrical performance. Aluminum oxide significantly enhances the mechanical strength of the ceramic. Lead-free glass powder further improves sintering performance and meets environmental protection requirements. The precise proportioning of each component and ultrafine particle size control ensure that the resistor sheet has excellent varistor characteristics, high mechanical strength, and long-term stability. In addition, modified zinc oxide particles can achieve uniform dispersion in anhydrous ethanol, significantly improving the uniformity of ball-milled wet materials, effectively shortening ball-milling time, and improving production efficiency.

[0022] 2. This invention provides a modified zinc oxide. In the first step, citric acid introduces carboxyl functional groups onto the zinc oxide surface through esterification. These carboxyl groups not only provide abundant surface active sites, significantly improving the dispersibility and compatibility of zinc oxide with other components, but also provide chemical anchoring points for subsequent functionalization, effectively preventing agglomeration. The reducing gases such as CO generated during the high-temperature sintering process of citric acid can create a favorable sintering atmosphere in localized areas, preventing excessive oxidation and maintaining the appropriate oxidation state of the material. In the second step, an ionic liquid arranges 1-ethyl-3-methylimidazolium cations in an orderly manner on the zinc oxide surface through electrostatic interactions. The ionic liquid possesses high ionic conductivity, good thermal stability, and excellent solubility. Its cations electrostatically bind with the negatively charged carboxyl groups, significantly reducing interfacial tension and improving the wettability and dispersion stability of the powder. The aromaticity and ionic properties of the imidazole ring endow the zinc oxide surface with unique electronic conduction and interfacial properties. The high ionic conductivity of the ionic liquid helps to optimize the grain boundary conductivity and improve the carrier transport behavior. This organic-inorganic hybrid structure not only maintains the excellent varistor properties of zinc oxide, but also further optimizes the nonlinear coefficient, leakage current and energy absorption capacity of the resistor, ultimately achieving a significant improvement in the overall performance of the resistor for surge arresters. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some schematic diagrams of certain embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1This is a microscopic SEM image of the resistor sheet prepared in Example 1. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0026] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0027] A method for preparing a resistor element for a surge arrester includes the following steps: (1) Disperse 10g of zinc oxide powder into 100~150mL of anhydrous toluene, add 0.1~0.3g of p-toluenesulfonic acid, sonicate for 30~60min, then slowly add 1~4g of citric acid under stirring, and magnetically stir at 110~130℃ for 4~7h. Filter, wash and dry the product to obtain intermediate zinc oxide. (2) Disperse 10g of intermediate zinc oxide into 100-150mL of anhydrous ethanol, sonicate for 20-40min, and then slowly add 0.6-1.2g of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate under nitrogen atmosphere and stir magnetically at 25-40℃ for 3-6h. Filter, wash and dry the product to obtain modified zinc oxide. (3) Disperse 80-95 parts of modified zinc oxide, 3-6 parts of bismuth oxide, 1-4 parts of antimony oxide, 1-4 parts of cobalt oxide, 0.6-1.2 parts of nickel oxide, 0.6-1.2 parts of manganese oxide, 0.4-1.0 parts of chromium oxide, 0.2-0.6 parts of aluminum oxide, and 1-4 parts of lead-free glass powder into a ball mill jar, then add anhydrous ethanol, and ball mill for 2-8 hours to obtain a slurry; spray granulate the slurry, then press it into shape, heat it to 400-900℃ at 2-5℃ / min, pre-fire and hold for 1-4 hours, spray aluminum on the upper and lower surfaces and coat the sides with insulating glaze, heat it to 700-1150℃ at 5℃ / min and hold for 5-15 minutes, then cool it to 800-1100℃ at 2℃ / min and hold for 5-8 hours, grind, clean and dry, and then spray aluminum electrodes to obtain the resistor sheet for the surge arrester.

[0028] The present invention will be further described below through specific embodiments.

[0029] Example 1

[0030] A method for preparing a resistor element for a surge arrester includes the following steps: (1) Disperse 10g of zinc oxide powder into 120mL of anhydrous toluene, add 0.3g of p-toluenesulfonic acid, sonicate for 45min, then slowly add 4g of citric acid under stirring, and magnetically stir the reaction at 130℃ for 4h. Filter, wash and dry the product to obtain intermediate zinc oxide. (2) 10g of intermediate zinc oxide was dispersed in 120mL of anhydrous ethanol and sonicated for 30min. Then, 1.2g of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate was slowly added under nitrogen atmosphere and stirred magnetically at 40℃ for 3h. The product was filtered, washed and dried to obtain modified zinc oxide. (3) 950g of modified zinc oxide, 60g of bismuth oxide, 40g of antimony oxide, 40g of cobalt oxide, 12g of nickel oxide, 12g of manganese oxide, 10g of chromium oxide, 6g of aluminum oxide, and 40g of lead-free glass powder were dispersed into a ball mill jar, and then anhydrous ethanol was added. The mixture was ball milled for 5 hours to obtain a slurry. The slurry was spray-granulated and then pressed into shape. The temperature was increased to 600℃ at 3℃ / min, and the preheating was maintained for 3 hours. Aluminum was sprayed on the upper and lower surfaces and insulating glaze was applied to the sides. The temperature was increased to 1100℃ at 5℃ / min and maintained for 10 minutes. Then the temperature was decreased to 950℃ at 2℃ / min and maintained for 7 hours. The mixture was ground, cleaned, dried, and then aluminum electrodes were sprayed to obtain the resistor sheet for the surge arrester.

[0031] Example 2

[0032] A method for preparing a resistor element for a surge arrester includes the following steps: (1) Disperse 10g of zinc oxide powder into 120mL of anhydrous toluene, add 0.2g of p-toluenesulfonic acid, sonicate for 45min, then slowly add 3g of citric acid under stirring, and magnetically stir the reaction at 125℃ for 5h. Filter, wash and dry the product to obtain intermediate zinc oxide. (2) 10g of intermediate zinc oxide was dispersed in 120mL of anhydrous ethanol and sonicated for 30min. Then, 1.0g of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate was slowly added under nitrogen atmosphere and stirred magnetically at 35℃ for 4h. The product was filtered, washed and dried to obtain modified zinc oxide. (3) 900g of modified zinc oxide, 50g of bismuth oxide, 30g of antimony oxide, 30g of cobalt oxide, 10g of nickel oxide, 10g of manganese oxide, 8g of chromium oxide, 5g of aluminum oxide, and 30g of lead-free glass powder were dispersed into a ball mill jar, and then anhydrous ethanol was added. The mixture was ball milled for 5 hours to obtain a slurry. The slurry was spray-granulated and then pressed into shape. The temperature was raised to 600℃ at 3℃ / min, and the pre-fired and kept at the temperature for 3 hours. Aluminum was sprayed on the upper and lower surfaces and insulating glaze was applied to the sides. The temperature was raised to 1100℃ at 5℃ / min and kept at the temperature for 10 minutes. Then the temperature was lowered to 950℃ at 2℃ / min and kept at the temperature for 7 hours. After grinding, cleaning and drying, aluminum electrodes were sprayed to obtain the resistor sheet for the surge arrester.

[0033] Example 3

[0034] A method for preparing a resistor element for a surge arrester includes the following steps: (1) Disperse 10g of zinc oxide powder into 120mL of anhydrous toluene, add 0.2g of p-toluenesulfonic acid, sonicate for 45min, then slowly add 2g of citric acid under stirring, and react magnetically at 115℃ for 6h. Filter, wash and dry the product to obtain intermediate zinc oxide. (2) Disperse 10g of intermediate zinc oxide into 120mL of anhydrous ethanol, sonicate for 30min, and then slowly add 0.8g of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate under nitrogen atmosphere and stir magnetically at 30℃ for 5h. Filter, wash and dry the product to obtain modified zinc oxide. (3) 850g of modified zinc oxide, 40g of bismuth oxide, 20g of antimony oxide, 20g of cobalt oxide, 8g of nickel oxide, 8g of manganese oxide, 6g of chromium oxide, 3g of aluminum oxide, and 20g of lead-free glass powder were dispersed into a ball mill jar, and then anhydrous ethanol was added. The mixture was ball milled for 5 hours to obtain a slurry. The slurry was spray-granulated and then pressed into shape. The temperature was increased to 600℃ at 3℃ / min, and the pre-fired and kept at the temperature for 3 hours. Aluminum was sprayed on the upper and lower surfaces and insulating glaze was applied to the sides. The temperature was increased to 1100℃ at 5℃ / min and kept at the temperature for 10 minutes. Then the temperature was decreased to 950℃ at 2℃ / min and kept at the temperature for 7 hours. After grinding, cleaning and drying, aluminum electrodes were sprayed to obtain the resistor sheet for the surge arrester.

[0035] Example 4

[0036] A method for preparing a resistor element for a surge arrester includes the following steps: (1) Disperse 10g of zinc oxide powder into 120mL of anhydrous toluene, add 0.1g of p-toluenesulfonic acid, sonicate for 45min, then slowly add 1~4g of citric acid under stirring, and react magnetically at 110℃ for 7h. Filter, wash and dry the product to obtain intermediate zinc oxide. (2) Disperse 10g of intermediate zinc oxide into 120mL of anhydrous ethanol, sonicate for 30min, and then slowly add 0.6g of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate under nitrogen atmosphere and stir magnetically at 25℃ for 6h. Filter, wash and dry the product to obtain modified zinc oxide. (3) 800g of modified zinc oxide, 30g of bismuth oxide, 10g of antimony oxide, 10g of cobalt oxide, 6g of nickel oxide, 6g of manganese oxide, 4g of chromium oxide, 2g of aluminum oxide, and 10g of lead-free glass powder were dispersed into a ball mill jar, and then anhydrous ethanol was added. The mixture was ball milled for 5 hours to obtain a slurry. The slurry was spray-granulated and then pressed into shape. The temperature was raised to 600℃ at 3℃ / min, and the preheating was maintained for 3 hours. Aluminum was sprayed on the upper and lower surfaces and insulating glaze was applied to the sides. The temperature was raised to 1100℃ at 5℃ / min and maintained for 10 minutes. Then the temperature was lowered to 950℃ at 2℃ / min and maintained for 7 hours. After grinding, cleaning and drying, aluminum electrodes were sprayed to obtain the resistor sheet for the surge arrester.

[0037] Comparative Example 1

[0038] A method for preparing a resistor element for a surge arrester includes the following steps: (1) Disperse 10g of zinc oxide powder into 120mL of anhydrous toluene, add 0.3g of p-toluenesulfonic acid, sonicate for 45min, then slowly add 4g of citric acid under stirring, and magnetically stir the reaction at 130℃ for 4h. Filter, wash and dry the product to obtain intermediate zinc oxide. (2) Disperse 900g of intermediate zinc oxide, 50g of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 60g of bismuth oxide, 40g of antimony oxide, 40g of cobalt oxide, 12g of nickel oxide, 12g of manganese oxide, 10g of chromium oxide, 6g of aluminum oxide, and 40g of lead-free glass powder into a ball mill jar, then add anhydrous ethanol, and ball mill for 5h to obtain a slurry; spray granulate the slurry, then press it into shape, heat it to 600℃ at 3℃ / min, pre-fire and hold for 3h, spray aluminum on the upper and lower surfaces and coat the sides with insulating glaze, heat it to 1100℃ at 5℃ / min and hold for 10min, then cool it to 950℃ at 2℃ / min and hold for 7h, grind, clean and dry, then spray aluminum electrodes to obtain the resistor sheet for the surge arrester.

[0039] Comparative Example 2

[0040] A method for preparing a resistor element for a surge arrester includes the following steps: 900g of zinc oxide, 50g of citric acid, 60g of bismuth oxide, 40g of antimony oxide, 40g of cobalt oxide, 12g of nickel oxide, 12g of manganese oxide, 10g of chromium oxide, 6g of aluminum oxide, and 40g of lead-free glass powder were dispersed in a ball mill jar, and then anhydrous ethanol was added. The mixture was ball milled for 5 hours to obtain a slurry. The slurry was spray-granulated, then pressed into shape, heated to 600℃ at 3℃ / min, pre-fired and held at that temperature for 3 hours, aluminum was sprayed on the top and bottom surfaces, and insulating glaze was applied to the sides. The temperature was then increased to 1100℃ at 5℃ / min and held for 10 minutes, then decreased to 950℃ at 2℃ / min and held for 7 hours. After grinding, cleaning, and drying, aluminum electrodes were sprayed to obtain the resistor sheet for the surge arrester.

[0041] Performance tests were conducted on the resistors prepared in Examples 1-4 and Comparative Examples 1-2. The DC 1mA reference voltage of the resistor was measured according to GB / T 11032-2020 "AC Gapless Metal Oxide Surge Arresters" 8.19; the leakage current of the resistor under 0.75 times the DC 1mA reference voltage was measured according to GB / T 11032-2020 "AC Gapless Metal Oxide Surge Arresters" 8.20; the residual voltage of the resistor under lightning current impulse was measured according to GB / T 11032-2020 "AC Gapless Metal Oxide Surge Arresters" 8.3, with the current waveform being an 8 / 20μs standard lightning current waveform; the aging coefficient Kct of the resistor was measured under artificial accelerated aging test conditions of 115℃, 1000 hours, and 90% charge rate according to GB / T 11032-2020 "AC Gapless Metal Oxide Surge Arresters"; and the results were also measured according to GB / T... 11032-2020 "AC Gapless Metal Oxide Surge Arresters" 8.24 High Current Impulse Withstand Test: Test whether the resistor element breaks down, flashes over, or explodes at 80kA; see Table 1 for specific data.

[0042] Table 1. Performance test results of the resistor element

[0043] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A resistor element for a surge arrester, characterized in that, It is made from the following components by weight: 80-95 parts modified zinc oxide, 3-6 parts bismuth oxide, 1-4 parts antimony oxide, 1-4 parts cobalt oxide, 0.6-1.2 parts nickel oxide, 0.6-1.2 parts manganese oxide, 0.4-1.0 parts chromium oxide, 0.2-0.6 parts aluminum oxide, and 1-4 parts lead-free glass powder; The modified zinc oxide was prepared by the following method steps: (1) Disperse zinc oxide powder into anhydrous toluene, add p-toluenesulfonic acid, sonicate, then slowly add citric acid while stirring, stir the reaction, filter, wash and dry the product to obtain intermediate zinc oxide; (2) Disperse the intermediate zinc oxide in anhydrous ethanol, sonicate it, and then slowly add 1-ethyl-3-methylimidazolium trifluoromethanesulfonate under nitrogen atmosphere and stir the reaction. Filter, wash and dry the product to obtain modified zinc oxide.

2. The resistor element for a surge arrester according to claim 1, characterized in that, In step (1), the particle size of zinc oxide powder is 0.1~1μm.

3. The resistor element for a surge arrester according to claim 1, characterized in that, In step (1), the ratio of zinc oxide, anhydrous toluene, p-toluenesulfonic acid, and citric acid is 10g: 100~150mL: 0.1~0.3g: 1~4g.

4. The resistor element for a surge arrester according to claim 1, characterized in that, In step (1), the ultrasonic treatment lasts for 30 to 60 minutes, and the stirring reaction is carried out under magnetic stirring at 110 to 130°C for 4 to 7 hours.

5. The resistor element for a surge arrester according to claim 1, characterized in that, In step (2), the ratio of intermediate zinc oxide, anhydrous ethanol, and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate is 10g: 100~150mL: 0.6~1.2g.

6. The resistor element for a surge arrester according to claim 1, characterized in that, In step (2), the ultrasonic treatment lasts for 20 to 40 minutes; the stirring reaction conditions are magnetic stirring at 25 to 40°C for 3 to 6 hours.

7. The resistor element for a surge arrester according to claim 1, characterized in that, Bismuth oxide, antimony oxide, cobalt oxide, nickel oxide, manganese oxide, chromium oxide, and aluminum oxide powders with a particle size <1μm, D 90 / D 10 <3; Lead-free glass powder particle size 1~5μm.

8. A method for preparing a resistor element for a surge arrester as described in any one of claims 1 to 7, characterized in that, The process includes the following steps: dispersing each component into a ball mill jar according to the weight parts, then adding anhydrous ethanol, and ball milling to obtain a slurry; spray granulating the slurry, then pressing and molding, pre-firing, spraying aluminum on the upper and lower surfaces, coating the sides with insulating glaze, sintering, grinding, cleaning and drying, and then spraying aluminum electrodes to obtain the resistor sheet for the surge arrester.

9. The preparation method according to claim 8, characterized in that, Ball milling for 2-8 hours; pre-firing conditions: heating to 400-900℃ at 2-5℃ / min and holding for 1-4 hours; sintering conditions: heating to 700-1150℃ at 5℃ / min and holding for 5-15 minutes, then cooling to 800-1100℃ at 2℃ / min and holding for 5-8 hours.

Images