Anti-aging zinc oxide varistor and preparation method and application thereof

Abstract

The invention belongs to the technical field of varistors, and relates to an anti-aging zinc oxide varistor as well as a preparation method and application thereof. The zinc oxide varistor sheet is prepared from the following raw materials in molar percentage: 92 percent to 96 percent of ZnO, 0.5 percent to 1.5 percent of Bi2O3, 0.5 percent to 1.5 percent of Sb2O3, 0.1 percent to 0.9 percent of Y2O3, 0.5 percent to 1.2 percent of NiO, 0.1 percent to 0.3 percent of B2O3, 0.7 percent to 1.2 percent of Co2O3, 0.3 percent to 0.7 percent of Cr2O3, 1 percent to 1.5 percent of SiO2 and 0.1 percent to 0.3 percent of Al (NO3) 3.9 H2O. Test results show that after the zinc oxide varistor is aged at 115 DEG C for 1000 hours, the leakage current IL is smaller than or equal to 5 microamperes, the aging coefficient Kct is stabilized between 0.97 and 1.03, and the zinc oxide varistor has excellent electrical performance and aging resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pressure-sensitive resistance sheets, and relates to an anti-aging zinc oxide pressure-sensitive resistance sheet and a preparation method and application thereof. BACKGROUND

[0002] In recent years, with the rapid growth of new energy power generation installed capacity, the expansion of power system supporting facilities and the continuous improvement of power grid voltage level, the requirements for safe and stable operation of power system are increasingly stringent. At the same time, a large number of old lines that have been in operation for many years are facing replacement, making the reliability problem of power grid equipment more prominent. As a key component of power system overvoltage protection, the development and research of high-performance zinc oxide pressure-sensitive resistance sheet has become the focus of the industry.

[0003] However, the zinc oxide resistance sheet produced by domestic enterprises at present is prone to aging failure in the process of long-term operation under the combined action of electric stress, thermal stress and mechanical stress, mainly showing that the leakage current gradually increases and the nonlinear coefficient (α value) decreases, resulting in the deterioration of voltage limiting ability and even the loss of overvoltage protection function. This problem not only shortens the service life of the resistance sheet itself, but also may cause power grid equipment failure, threatening the safe and stable operation of the power system. Especially in high-voltage and super-high-voltage application scenarios, the resistance sheet needs to withstand higher energy load and more severe operating environment, and the anti-aging performance of the existing products has been difficult to meet the demand of the current power industry for high-reliability and long-life protection devices. SUMMARY

[0004] In order to solve the problems in the prior art, the application provides an anti-aging zinc oxide pressure-sensitive resistance sheet and a preparation method and application thereof, which have excellent electrical performance and anti-aging characteristics.

[0005] In order to achieve the above-mentioned purpose, the following technical solutions are adopted: In a first aspect, the application provides an anti-aging zinc oxide pressure-sensitive resistance sheet, which comprises the following raw materials in terms of mole percentage: 92%~96% ZnO, 0.5%~1.5% Bi2O3, 0.5%~1.5% Sb2O3, 0.1%~0.9% Y2O3, 0.5%~1.2% NiO, 0.1%~0.3% B2O3, 0.7%~1.2% Co2O3, 0.3%~0.7% Cr2O3, 1%~1.5% SiO2, 0.1%~0.3% Al(NO3)3 9H2O.

[0006] In a second aspect, the application provides a preparation method of an anti-aging zinc oxide pressure-sensitive resistance sheet, comprising the following steps: The following raw materials are weighed according to the percentage of moles: ZnO, Bi2O3, Sb2O3, Y2O3, NiO, B2O3, Co2O3, Cr2O3, SiO2 and Al(NO3)3 9H2O, after the weighing, the raw materials are mixed to obtain a mixture; The binder, dispersant and defoaming agent are added to the mixture to obtain a mixed granular material; The mixed granular material is pressed to obtain a zinc oxide resistor wafer; The zinc oxide resistor wafer is subjected to degassing, sintering and cooling to obtain a zinc oxide resistor rough wafer; The zinc oxide resistor rough wafer is coated with an insulating glaze, and is subjected to sintering and cooling to obtain a zinc oxide resistor sintered body; The zinc oxide resistor sintered body is subjected to heat treatment, and is coated with an insulating layer and an aluminum-plated electrode to obtain the zinc oxide varistor.

[0007] Preferably, the binder is polyvinyl alcohol, the dispersant is ammonium polyacrylate, and the defoaming agent is tributyl phosphate.

[0008] Preferably, based on the total mass of the raw materials, the addition amount of the binder is 3wt%-7wt%, the addition amount of the dispersant is 0.5wt%-1.5wt%, and the addition amount of the defoaming agent is 0.1wt%-0.3wt%.

[0009] Preferably, the degassing process includes: increasing the temperature to 350-450℃ at a temperature increasing rate of 70-100℃ / h, and maintaining the temperature for 2-4h.

[0010] Preferably, the sintering process includes: increasing the temperature to 700-850℃ at a temperature increasing rate of 70-100℃ / h, and maintaining the temperature for 4-6h; increasing the temperature to 1000-1250℃ at a temperature increasing rate of 20-40℃ / h, and maintaining the temperature for 1-2h.

[0011] Preferably, the heat treatment process includes: increasing the temperature from room temperature to 490-550℃ at a temperature increasing rate of 50-100℃ / h, and maintaining the temperature for 1-4h, and then decreasing the temperature to room temperature at a temperature decreasing rate of 10-17℃ / h.

[0012] Preferably, before the mixed granular material is pressed, the process further includes the steps of ball milling, drying, granulating, grinding and sieving.

[0013] Preferably, before the zinc oxide resistor sintered body is subjected to heat treatment, the process further includes the steps of grinding and cleaning the zinc oxide resistor sintered body.

[0014] In a third aspect, the application provides application of the anti-aging zinc oxide varistor chip in the lightning arrester field.

[0015] Compared with the prior art, the application has the following beneficial effects: The B2O3 introduced in the application makes B 3+ The ion enters the interstitial site of the crystal lattice, thereby inhibiting the formation of VO-Zni (oxygen vacancy-interstitial zinc) composite defects from the source; secondly, the occupation of the interstitial site by the Al 3+ The occupation of the interstitial site by the Al donor ion effectively blocks the migration channel of zinc ions; at the same time, the optimized Y2O3-Bi2O3-Sb2O3 ternary system stabilizes the grain boundary structure. These synergistic effects reduce the zinc interstitial concentration by more than 40%, significantly improve the stability of the Schottky barrier, and solve the aging problem of traditional ZnO varistor chips caused by zinc interstitials (Zni) and bismuth ion migration under the action of high-voltage electric field and thermal stress. Test results show that the leakage current IL of the zinc oxide varistor chip of the application is less than or equal to 5 mu A after 1000 hours of aging at 115 DEG C, and the aging coefficient Kct is stable between 0.97 and 1.03, while the production cost is reduced, and the performance and economic benefits are doubled. DETAILED DESCRIPTION

[0016] To enable those skilled in the art to understand the features and effects of the application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings understood by those skilled in the art of the application, and in the event of conflict, the definitions in the specification shall prevail.

[0017] Theories or mechanisms described and disclosed herein, whether correct or not, should not limit the scope of the application in any way, i.e., the application can be practiced without being limited to any particular theory or mechanism.

[0018] In this paper, all features defined in the form of numerical range or percentage range, such as numerical value, quantity, content and concentration, are for the sake of brevity and convenience. Therefore, the description of numerical range or percentage range should be considered to have covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0019] In this paper, unless otherwise specified, "comprise", "include", "contain", "have" or similar terms cover the meaning of "consist of" and "consist essentially of", for example, "A comprises a" covers the meaning of "A comprises a and other" and "A only comprises a".

[0020] Herein, all possible combinations of the technical features in each embodiment or example are not described in order to make the description simple. Therefore, as long as the combinations of the technical features do not contradict each other, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope of the present specification.

[0021] A first object of the present application is to provide an anti-aging zinc oxide varistor disc, which comprises the following raw materials in terms of mole percentage: 92-96% ZnO, 0.5-1.5% Bi2O3, 0.5-1.5% Sb2O3, 0.1-0.9% Y2O3, 0.5-1.2% NiO, 0.1-0.3% B2O3, 0.7-1.2% Co2O3, 0.3-0.7% Cr2O3, 1-1.5% SiO2, and 0.1-0.3% Al(NO3)3 9H2O.

[0022] In the system of the present application, ZnO provides the basis for the pressure-sensitive properties as the matrix material, and through the synergistic doping of Bi2O3 and Sb2O3, a ternary complex grain boundary modification system is formed with Y2O3, which significantly enhances the stability of the grain boundary potential barrier. Through the formation of a unique low-temperature glass phase network by B2O3 and SiO2, the grain boundary defects can be effectively plugged during the sintering process, and the concentration of grain boundary oxygen vacancies is reduced. The multivalent state characteristics of transition metal oxides NiO, Co2O3 and Cr2O3 realize the precise regulation of grain boundary defects; the introduction of Al(NO3)3 9H2O introduces Al 3+ donor doping, and forms a compensating doping effect with the acceptor elements. The zinc oxide varistor disc of the present application significantly improves the anti-aging properties of the product through the multi-component synergistic mechanism, while maintaining excellent electrical properties, so that the varistor can still maintain stable protection function in harsh environments such as high temperature and high pressure, solving the long-standing aging problem of zinc oxide varistors in the industry.

[0023] A second object of the present application is to provide a preparation method of an anti-aging zinc oxide varistor disc, comprising the following steps: The following raw materials are weighed according to mole percentage: ZnO, Bi2O3, Sb2O3, Y2O3, NiO, B2O3, Co2O3, Cr2O3, SiO2 and Al(NO3)3 9H2O, and after weighing, the raw materials are mixed to obtain a mixture; A binder, a dispersant and a defoaming agent are added to the mixture to obtain a mixed granular material; The mixed particle material is subjected to ball milling to obtain a zinc oxide primary slurry, the zinc oxide primary slurry is dried and then placed in a pressure spray granulation tower for granulation to prepare a powder with fluidity and bulk density, and the particle size is controlled to be 60-100 mu m; then the powder is subjected to grinding and sieving treatment, and is pressed into a certain shape and size in a mold under the action of external force to obtain a zinc oxide resistor blank; The zinc oxide resistor blank is subjected to glue removal, sintering and natural cooling to obtain a zinc oxide resistor rough blank; An insulating glaze (preferably with a thickness of 0.2 mm) is coated on the side surface of the zinc oxide resistor rough blank, the zinc oxide resistor sintered body is obtained after sintering at 1000 DEG C and cooling; The zinc oxide resistor sintered body is subjected to end face grinding by using a double-sided polishing machine, so that the flatness is less than 0.05 mm, and then the zinc oxide resistor sintered body is subjected to cleaning, heat treatment, spraying of an aluminum plated electrode and coating of an insulating layer to obtain the zinc oxide varistor.

[0024] The application adopts a multi-element oxide composite formula (Bi2O3, Y2O3, etc.) combined with a Bi2O3-SiO2 glass phase forming agent to form a uniform grain boundary structure in the sintering process, effectively inhibits abnormal growth of ZnO grains, and enhances the large current impact resistance of the varistor; by introducing Y2O3 and Cr2O3 and other rare earth and transition metal oxides, the grain boundary barrier stability is synergistically improved, so that the resistor maintains excellent non-linear coefficient and low leakage current characteristics under long-term working conditions; the side surface insulating glaze design is combined with the later heat treatment process, not only reduces the risk of partial discharge, but also further optimizes the microstructure through stress release, and the double protection of the aluminum plated electrode and the surface insulating layer makes the final product have high weather resistance, anti-aging and stable electrical performance, and is especially suitable for long-term use in harsh environments.

[0025] The glue removal process includes: increasing the temperature to 350-450 DEG C at a temperature increasing rate of 70-100 DEG C / h, and keeping the temperature for 2-4 h, which ensures sufficient decomposition of the organic matter without damaging the blank structure.

[0026] The sintering process promotes uniform distribution of the grain boundary phase and controls the grain size, including: increasing the temperature to 700-850 DEG C at a temperature increasing rate of 70-100 DEG C / h, and keeping the temperature for 4-6 h; increasing the temperature to 1000-1250 DEG C at a temperature increasing rate of 20-40 DEG C / h, and keeping the temperature for 1-2 h.

[0027] The heat treatment process includes: increasing the temperature from room temperature to 490-550 DEG C at a temperature increasing rate of 50-100 DEG C / h, and keeping the temperature for 1-4 h, and then decreasing the temperature to room temperature at a temperature decreasing rate of 10-17 DEG C / h, which effectively stabilizes the microstructure of the material and significantly reduces the concentration of zinc interstitial defects.

[0028] In one embodiment of the present application, the binder is polyvinyl alcohol, which has good adhesion and plasticity, ensuring that the green body has sufficient mechanical strength during press forming, and its thermal decomposition temperature is moderate, which is conducive to the subsequent glue removal process; the dispersant is ammonium polyacrylate, which effectively reduces the powder agglomeration, so that each component is uniformly distributed, thereby optimizing the microstructure after sintering and improving the electrical consistency of the resistor disc; the defoaming agent is tributyl phosphate, which effectively inhibits the generation of bubbles during the preparation of the slurry, avoiding internal defects of the green body. And based on the total mass of the raw materials, the addition amount of the binder is 3wt%-7wt%, the addition amount of the dispersant is 0.5wt%-1.5wt%, and the addition amount of the defoaming agent is 0.1wt%-0.3wt%.

[0029] In actual press forming operation, appropriate pressing speed, pressure size, pressure holding time and exhaust method are selected according to the size of the green body to ensure that the green body has uniform density, no layering or cracking defects, etc.

[0030] In one embodiment of the present application, the ball mill uses zirconium balls as the ball mill medium, and the mass ratio of material:ball:water is controlled to be 1:2:1, and the grinding time is 12-24h.

[0031] A third object of the present application is to provide an application of the anti-aging zinc oxide varistor disc in the field of lightning arresters, which can significantly prolong the service life of the lightning arresters, improve the protection performance and safety reliability, reduce the economic cost and energy loss, ensure the stable operation of the power system while realizing high efficiency and energy saving, and has significant industrialization promotion value.

[0032] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. In addition, it should be understood that after reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0033] In the following examples, conventional instruments and equipment in the art are used. In the following examples, the experimental methods not specified in the specific conditions are usually carried out according to the conventional conditions or according to the conditions recommended by the manufacturer. In the following examples, various raw materials are used, unless otherwise specified, conventional commercially available products are used, and the specifications are conventional specifications in the art. In the specification of the present application and the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.

[0034] Example 1 The following raw materials were weighed according to the mole percentage: 96% ZnO, 0.5% Bi2O3, 0.5% Sb2O3, 0.1% Y2O3, 0.5% NiO, 0.1% B2O3, 0.7% Co2O3, 0.3% Cr2O3, 1% SiO2, and 0.3% Al(NO3)3 9H2O, after weighing, the raw materials were mixed to obtain a mixture; To the mixture, 3% polyvinyl alcohol, 0.5% ammonium polyacrylate, and 0.3% tributyl phosphate were added, to obtain a mixed granular material; The mixed granular material was ball milled (using zirconium balls as the ball milling medium, the mass ratio of material:ball:water was 1:2:1) for 12 h to obtain a zinc oxide primary slurry. The zinc oxide primary slurry was dried and then placed in a pressure spray granulation tower for granulation to prepare a powder with a certain fluidity and bulk density, and the particle size was controlled at 60 μm. The powder was then ground, sieved, and pressed into a certain shape and size mold under an external force to obtain a zinc oxide resistor blank; The zinc oxide resistor blank was placed in a box furnace, and the temperature was raised to 350℃ at a rate of 70℃ / h, and kept for 4 h. The temperature was then raised to 700℃ at a rate of 70℃ / h, and kept for 6 h. The temperature was then raised to 1000℃ at a rate of 20℃ / h, and kept for 2 h. After natural cooling, a zinc oxide resistor rough blank was obtained; The zinc oxide resistor rough blank was coated with an insulating glaze, and after sintering at 1000℃ and cooling, a zinc oxide resistor sintered body was obtained; The zinc oxide resistor sintered body was ground on the end face using a double-sided polishing machine to make the flatness less than 0.05 mm, and was cleaned. The temperature was raised to 490℃ at a rate of 50℃ / h from room temperature, and kept for 4 h. Then the temperature was lowered to room temperature at a rate of 10℃ / h. After that, an aluminum plated electrode and an insulating layer were sprayed to obtain the zinc oxide varistor resistor.

[0035] Example 2 The following raw materials were weighed according to the mole percentage: 94% ZnO, 1% Bi2O3, 1% Sb2O3, 0.3% Y2O3, 0.8% NiO, 0.2% B2O3, 0.9% Co2O3, 0.4% Cr2O3, 1.2% SiO2, and 0.2% Al(NO3)3 9H2O, after weighing, the raw materials were mixed to obtain a mixture; To the mixture, 4% polyvinyl alcohol, 0.8% ammonium polyacrylate, and 0.25% tributyl phosphate were added, to obtain a mixed granular material; The mixed granular material is subjected to ball milling (using zirconium balls as the ball milling medium, the mass ratio of material:ball:water being 1:2:1) for 16 hours to obtain a primary slurry of zinc oxide, which is dried and then placed in a pressure spray granulation tower for granulation to prepare a powder having a certain fluidity and bulk density, the particle size being controlled at 70 μm; the powder is further subjected to grinding and sieving treatment, and is pressed into a certain shape and size in a mold under a certain external force to obtain a zinc oxide resistor blank; The zinc oxide resistor blank is placed in a box furnace, heated at a rate of 80 ℃ / h to 380 ℃, and kept at this temperature for 3 hours, heated at a rate of 80 ℃ / h to 750 ℃, and kept at this temperature for 6 hours, and heated at a rate of 25 ℃ / h to 1100 ℃, and kept at this temperature for 2 hours, and then naturally cooled to obtain a zinc oxide resistor rough blank; The zinc oxide resistor rough blank is coated with an insulating glaze on the side surface, and after sintering at 1000 ℃ and cooling, a zinc oxide resistor sintered body is obtained; The zinc oxide resistor sintered body is subjected to end face grinding using a double-sided polishing machine, so that the flatness is less than 0.05 mm, and is cleaned, and then heated at a rate of 60 ℃ / h from room temperature to 500 ℃, and kept at this temperature for 4 hours, and then cooled at a rate of 12 ℃ / h to room temperature, and then an aluminum plating electrode and an insulating layer are sprayed to obtain the zinc oxide varistor resistor.

[0036] Example 3 The following raw materials are weighed according to the molar percentage: 93% ZnO, 1.2% Bi2O3, 1.2% Sb2O3, 0.5% Y2O3, 1.0% NiO, 0.2% B2O3, 1.0% Co2O3, 0.5% Cr2O3, 1.3% SiO2, and 0.1% Al(NO3)3 9H2O, after weighing, the raw materials are mixed to obtain a mixture; 5% polyvinyl alcohol, 1.0% ammonium polyacrylate, and 0.2% tributyl phosphate are added to the mixture to obtain a mixed granular material; The mixed granular material is subjected to ball milling (using zirconium balls as the ball milling medium, the mass ratio of material:ball:water being 1:2:1) for 16 hours to obtain a primary slurry of zinc oxide, which is dried and then placed in a pressure spray granulation tower for granulation to prepare a powder having a certain fluidity and bulk density, the particle size being controlled at 70 μm; the powder is further subjected to grinding and sieving treatment, and is pressed into a certain shape and size in a mold under a certain external force to obtain a zinc oxide resistor blank; The zinc oxide resistor blank is placed in a box furnace, heated at a rate of 80 ℃ / h to 380 ℃, and kept at this temperature for 3 hours, heated at a rate of 80 ℃ / h to 750 ℃, and kept at this temperature for 6 hours, and heated at a rate of 25 ℃ / h to 1100 ℃, and kept at this temperature for 2 hours, and then naturally cooled to obtain a zinc oxide resistor rough blank; coating insulating glaze on the side of the zinc oxide varistor rough blank, and obtaining the zinc oxide varistor sintered body after sintering at 1000℃ and cooling; polishing machine, so that the flatness is less than 0.05mm, and cleaning, and then spraying aluminum plated electrode and coating insulating layer after increasing the temperature from room temperature to 520℃ at a rate of 75℃ / h and keeping for 3h and decreasing the temperature to room temperature at a rate of 14℃ / h, to obtain the zinc oxide varistor.

[0037] Example 4 The following raw materials are weighed according to the mole percentage: 92.7% ZnO, 0.5% Bi2O3, 1.0% Sb2O3, 0.8% Y2O3, 1.2% NiO, 0.3% B2O3, 1.2% Co2O3, 0.7% Cr2O3, 1.5% SiO2 and 0.1% Al(NO3)3. 9H2O, and after weighing, the raw materials are mixed to obtain the mixed material; 6% polyvinyl alcohol, 1.2% ammonium polyacrylate and 0.15% tributyl phosphate are added to the mixed material, to obtain the mixed granular material; The mixed granular material is ball milled (using zirconium balls as the ball milling medium, the mass ratio of material:ball:water being 1:2:1) for 20h to obtain zinc oxide primary slurry, which is dried and placed in a pressure spray granulation tower for granulation to prepare a powder with certain fluidity and bulk density, and the particle size is controlled at 90μm; and then the powder is ground, sieved and pressed into a zinc oxide varistor blank body in a mold with a certain shape and size under certain external force; The zinc oxide varistor blank body is placed in a box furnace, and the temperature is increased to 420℃ at a rate of 90℃ / h and kept for 2h, and then increased to 800℃ at a rate of 90℃ / h and kept for 4h, and then increased to 1200℃ at a rate of 35℃ / h and kept for 1h, and then naturally cooled to obtain the zinc oxide varistor rough blank; coating insulating glaze on the side of the zinc oxide varistor rough blank, and obtaining the zinc oxide varistor sintered body after sintering at 1000℃ and cooling; polishing machine, so that the flatness is less than 0.05mm, and cleaning, and then spraying aluminum plated electrode and coating insulating layer after increasing the temperature from room temperature to 520℃ at a rate of 75℃ / h and keeping for 3h and decreasing the temperature to room temperature at a rate of 14℃ / h, to obtain the zinc oxide varistor.

[0038] Example 5 The following raw materials were weighed according to the percentage by mole: 92% ZnO, 1.5% Bi2O3, 1.5% Sb2O3, 0.9% Y2O3, 1.2% NiO, 0.3% B2O3, 1.1% Co2O3, 0.7% Cr2O3, 1.5% SiO2 and 0.3% Al(NO3)3 9H2O, after weighing, the raw materials were mixed to obtain a mixture; To the mixture, 7% polyvinyl alcohol, 1.5% ammonium polyacrylate and 0.1% tributyl phosphate were added, to obtain a mixed granular material; The mixed granular material was ball milled (using zirconium balls as the ball milling medium, the mass ratio of material:ball:water was 1:2:1) for 24 hours to obtain a zinc oxide primary slurry. The zinc oxide primary slurry was dried and then placed in a pressure spray granulation tower for granulation to prepare a powder having a certain fluidity and bulk density, with a particle size controlled at 100 μm. The powder was then ground, sieved and pressed into a certain shape and size in a mold under an external force to obtain a zinc oxide resistor wafer body. The zinc oxide resistor wafer body was placed in a box furnace, and the temperature was raised to 450°C at a rate of 100°C / h, and then kept at 450°C for 2 hours. The temperature was then raised to 850°C at a rate of 100°C / h, and then kept at 850°C for 4 hours. The temperature was then raised to 1250°C at a rate of 40°C / h, and then kept at 1250°C for 1 hour. After natural cooling, a zinc oxide resistor rough wafer was obtained. The zinc oxide resistor rough wafer was coated with an insulating glaze on the side surface, and after sintering at 1000°C and cooling, a zinc oxide resistor sintered body was obtained. The zinc oxide resistor sintered body was polished on the end surface using a double-sided polishing machine to make the flatness less than 0.05 mm, and was cleaned. The temperature was raised to 550°C at a rate of 100°C / h from room temperature, and then kept at 550°C for 1 hour. The temperature was then lowered to room temperature at a rate of 17°C / h. After that, an aluminum electrode was sprayed and plated, and an insulating layer was coated to obtain the zinc oxide varistor resistor.

[0039] Performance test: The 32 / 36 / 42 / 48 / 60 mm zinc oxide varistor resistors prepared in Example 1 were subjected to a 1000 hour aging test under the condition of applying the maximum continuous operating voltage and controlling the resistor surface temperature at 115°C±4. The test results are shown in Table 1. Table 1 Performance data of the 32 / 36 / 42 / 48 / 60 mm resistors prepared in Example 1

[0040] The 42mm zinc oxide varistor disc prepared according to Examples 2-5 was tested after 1000 hours of aging test under the condition of applying maximum continuous operating voltage and controlling the disc surface temperature at 115°C±4, and the test results are shown in Table 2. Table 2 Performance data of 42mm discs prepared according to Examples 2-4

[0041] In summary, it can be seen from Examples 1-5 that the anti-aging zinc oxide varistor disc prepared by the preparation process of the present application has a leakage current I L low, an aging coefficient K ct tending to 1, a significant anti-aging property, and can improve the protection performance, operating life and safety reliability of the lightning arrester.

[0042] The above merely illustrates the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A zinc oxide varistor resistant to aging, characterized in that, The zinc oxide varistor comprises the following raw materials by molar percentage: 92%~96% ZnO, 0.5%~1.5% Bi₂O₃, 0.5%~1.5% Sb₂O₃, 0.1%~0.9% Y₂O₃, 0.5%~1.2% NiO, 0.1%~0.3% B₂O₃, 0.7%~1.2% Co₂O₃, 0.3%~0.7% Cr₂O₃, 1%~1.5% SiO₂, 0.1%~0.3% Al(NO₃)₃ 9H2O.

2. The method for preparing an aging-resistant zinc oxide varistor according to claim 1, characterized in that, Includes the following steps: Weigh out the following raw materials by molar percentage: ZnO, Bi2O3, Sb2O3, Y2O3, NiO, B2O3, Co2O3, Cr2O3, SiO2, and Al(NO3)3. After weighing all the raw materials, mix them to obtain a mixture. Add binder, dispersant and defoamer to the mixture to obtain mixed granular material; The mixed granular material is pressed to obtain a zinc oxide resistor blank; The zinc oxide resistor blank is obtained by debinding, sintering and cooling the zinc oxide resistor blank. An insulating glaze is coated on the side of a zinc oxide resistor blank, and after sintering and cooling, a sintered zinc oxide resistor body is obtained. After heat treatment of the zinc oxide varistor sheet sintered body, aluminum-plated electrodes are sprayed and an insulating layer is coated to obtain the zinc oxide varistor sheet.

3. The method for preparing an aging-resistant zinc oxide varistor according to claim 2, characterized in that, The adhesive is polyvinyl alcohol; the dispersant is ammonium polyacrylate; and the defoamer is tributyl phosphate.

4. The method for preparing an aging-resistant zinc oxide varistor according to claim 2, characterized in that, Based on the total mass of raw materials, the amount of adhesive added is 3wt%~7wt%, the amount of dispersant added is 0.5wt%~1.5wt%, and the amount of defoamer added is 0.1wt%~0.3wt%.

5. The method for preparing an aging-resistant zinc oxide varistor according to claim 2, characterized in that, The adhesive removal process includes: heating to 350-450℃ at a heating rate of 70-100℃ / h and holding at that temperature for 2-4 hours.

6. The method for preparing an aging-resistant zinc oxide varistor according to claim 5, characterized in that, The sintering process includes: The temperature is increased to 700-850℃ at a heating rate of 70-100℃ / h and held for 4-6 hours. The temperature is increased to 1000-1250℃ at a heating rate of 20-40℃ / h and held for 1-2 hours.

7. The method for preparing an aging-resistant zinc oxide varistor according to claim 2, characterized in that, The heat treatment process includes: raising the temperature from room temperature to 490-550°C at a heating rate of 50-100°C / h, holding the temperature for 1-4 hours, and then cooling the temperature to room temperature at a cooling rate of 10-17°C / h.

8. The method for preparing an aging-resistant zinc oxide varistor according to claim 2, characterized in that, Before the mixed granular material is pressed, the process also includes ball milling, drying, granulation, grinding, and sieving.

9. The method for preparing an aging-resistant zinc oxide varistor according to claim 2, characterized in that, Before heat treatment of the zinc oxide resistor sheet sintered body, the process also includes grinding and cleaning the zinc oxide resistor sheet sintered body.

10. The application of the aging-resistant zinc oxide varistor sheet according to claim 1 in the field of surge arresters.

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