Alumina-based porcelain insulator and preparation method thereof

Abstract

The application relates to the technical field of alumina ceramic material preparation, in particular to an alumina-based porcelain insulator body and a preparation method thereof. The alumina-based porcelain insulator body is prepared from interface-repairing alumina and a sintering aid; the mass ratio of the interface-repairing alumina to the sintering aid is 100:(5-10); the sintering aid is at least one of zirconium oxide, rare earth oxide, calcium oxide, magnesium oxide, silicon dioxide and manganese dioxide; the interface-repairing alumina is interface-metal-atom-repairing alumina, the interface-metal-atom-repairing alumina comprises carrier alumina and metal atoms which are anchored to defect points of the carrier alumina in the form of single atoms, and the metal atoms at least comprise Al. The alumina-based porcelain insulator body has the advantages of small dielectric constant and low dielectric loss, and meets the electrical performance requirements of an insulator for extra-high voltage power transmission.

Description

Technical Field

[0001] This invention relates to the field of alumina ceramic material preparation technology, and in particular to an alumina-based ceramic insulator body and its preparation method. Background Technology

[0002] Alumina ceramics possess high insulation, chemical corrosion resistance, high strength, high wear resistance, and high temperature resistance, making them widely used in the insulation support of power equipment such as high-voltage switches, circuit breakers, transformers, and insulators. Alumina ceramic insulators in power systems serve the functions of conductor isolation, support, and fixation. With the development of power transmission networks towards ultra-high voltage transmission, higher requirements are being placed on the electrical performance of alumina ceramic insulators.

[0003] Alumina ceramics have a dielectric constant of around 10 and a dielectric strength of 10-15 kV / mm at 1 MHz. Aluminum nitride ceramics have a dielectric constant of around 8.5, and silicon nitride ceramics have a dielectric constant of around 7.5. Compared to similar aluminum nitride and silicon nitride ceramics, alumina ceramics have a higher dielectric constant and relatively higher dielectric loss. While their dielectric strength is comparable to that of silicon nitride ceramics, it is lower. The advantage of alumina ceramics lies in their relatively low production cost, leading to their widespread application in the insulation and support of power equipment.

[0004] With the development of power transmission grids towards ultra-high voltage (UHV) transmission, alumina ceramic insulators, due to their high dielectric constant and high dielectric loss, can no longer meet the requirements for UHV power transmission insulators. There is an urgent need for a low dielectric constant alumina-based ceramic insulator body to meet the requirements of UHV power transmission insulators. Summary of the Invention

[0005] To address the issues of excessively high dielectric constant and dielectric loss in existing alumina ceramic insulators, this invention provides an alumina-based ceramic insulator body and its preparation method.

[0006] The alumina-based ceramic insulator body provided by this invention is achieved through the following technical solution:

[0007] A ceramic insulator body based on alumina is made of interface-repairing alumina and sintering aids; the mass ratio of the interface-repairing alumina to the sintering aids is 100:(5-10); the sintering aids are at least one of zirconium oxide, rare earth oxides, calcium oxide, magnesium oxide, silicon dioxide, and manganese dioxide; the interface-repairing alumina is an interface metal atom-repairing alumina, which includes a carrier alumina and metal atoms anchored to the defect sites of the carrier alumina in the form of single atoms, wherein the metal atoms include at least Al.

[0008] In this invention, defects on the surface of calcined alumina are repaired by single atoms. These single atoms compensate for oxygen vacancies generated during calcination through covalent bonds. By reducing surface defects of alumina, the overall dielectric loss is reduced. The dielectric constant and dielectric loss of the alumina-based ceramic insulator prepared using this method are significantly reduced, which meets the electrical performance requirements of insulators for ultra-high voltage power transmission.

[0009] Preferably, the preparation method of the interface metal atom repair type alumina is as follows:

[0010] Step 1: Prepare a modified acid solution with a mass concentration of 1-5%. Place 10 parts by weight of alumina in 100-200 parts by weight of the modified acid solution and ultrasonically disperse for 4-8 hours. Dry to obtain organic acid modified alumina.

[0011] Step 2: Prepare a water-soluble metal salt solution with a concentration of 0.5-5 g / L. The water-soluble metal salt solution includes at least aluminum nitrate. Mix 10 parts by weight of organic acid-modified alumina with 50-1000 parts by weight of the water-soluble metal salt solution by mechanical stirring for 1-4 hours, ultrasonic dispersion for 1-4 hours, aging for 12-24 hours, and drying to obtain solid powder.

[0012] Step 3: The solid powder is ball-milled to refine it. The refined powder is then calcined in air at a temperature of 500-800℃ for 3-8 hours at a rate of 5-10℃ / min, followed by a temperature drop to 200-250℃ at a rate of 10-20℃ / min. The furnace is then allowed to cool naturally to room temperature. The resulting powder, after ball milling, yields a median diameter D. 50 Alumina with an interfacial metal atom thickness of 0.2-2.5 μm is used for interfacial metal atom repair.

[0013] The preparation method of the interface metal atom repair type alumina in this invention is simple and easy to achieve large-scale production.

[0014] Preferably, the modified acid solution is prepared from water and organic acid, and the water is required to be deionized water or pure water; the organic acid is at least one selected from tartaric acid, tannic acid, malic acid, citric acid, succinic acid, and oxalic acid.

[0015] More preferably, the modified acid solution is made from pure water, tannic acid, and citric acid, and the mass ratio of tannic acid to citric acid in the modified acid solution is 1:1.

[0016] Preferably, in step three, the solid powder is ball-milled to refine it. The refined powder is then calcined in air at a temperature of 600-650°C (8-10°C / min) for 4-6 hours, followed by a temperature drop to 200-250°C (20°C / min). The furnace is then allowed to cool naturally to room temperature. The resulting powder, after ball-milling, yields a median diameter D. 50 Alumina with an interfacial metal atom thickness of 0.2-2.5 μm is used for interfacial metal atom repair.

[0017] The interface metal alumina with good defect repairability prepared by adopting the above technical solution has better electrical performance, and the alumina ceramic insulator prepared by it has better electrical performance, which better meets the electrical performance requirements of insulators for ultra-high voltage power transmission.

[0018] Preferably, the sintering aid is composed of zirconium oxide, lanthanum oxide, cerium oxide, calcium oxide, magnesium oxide, and silicon dioxide.

[0019] Preferably, the sintering aid is composed of the following raw materials in parts by weight: 100 parts zirconium oxide, 5-10 parts lanthanum oxide, 5-10 parts cerium oxide, 10-25 parts calcium oxide, 10-25 parts magnesium oxide, and 20-40 parts silicon dioxide.

[0020] In this invention, the zirconia sintering forms a tetragonal T-phase zirconia (t-ZrO2). Under stress, t-ZrO2 undergoes a stress-induced phase transformation, relaxing the stress field at the crack tip, increasing crack propagation resistance, and effectively improving overall density, seismic resistance, flexural strength, and impact toughness. Lanthanum oxide and cerium oxide can promote the reaction of alumina with other sintering aids to generate a liquid phase with a lower melting point, effectively reducing its sintering temperature. Through capillary action in the grain gaps, the liquid phase fills the voids, densifying the ceramic and improving overall density, mechanical properties, impact toughness, and seismic resistance. Calcium oxide undergoes eutectic reaction with alumina during sintering, which is beneficial for solid-phase reactions. Magnesium oxide becomes a nucleus for crystal growth during sintering, which helps eliminate large voids in the preform, promoting densification and inhibiting crystal growth. Silica fills the pores between alumina crystals, improving grain boundary bonding, enhancing the compressive strength and wear resistance of ceramics, and reducing the coefficient of thermal expansion, thermal stress, and thermal shock resistance. At high temperatures, it generates a liquid phase, promoting grain refinement, lowering the sintering temperature, and increasing bulk density. In summary, alumina ceramic insulators prepared using the above-mentioned compounded sintering aids improve overall density, wear resistance, seismic performance, compressive strength, and impact toughness while ensuring electrical performance, better meeting the performance requirements of ultra-high voltage power transmission insulators.

[0021] Preferably, the alumina-based ceramic insulator body is made of interface-repairing alumina, sintering aid, and fluorophlogopite powder, and the mass ratio of the interface-repairing alumina to the sintering aid and the fluorophlogopite powder is 100:(5-10):(5-10).

[0022] The electrical breakdown strength of alumina ceramic insulators can be improved by incorporating fluorinated phlogopite powder. Furthermore, the dielectric constant of fluorinated phlogopite powder itself is between 5 and 6.5, which does not affect the dielectric properties of alumina ceramic insulators. On the contrary, it can improve the dielectric and mechanical properties of alumina ceramic insulators.

[0023] The present invention provides a method for preparing an alumina-based ceramic insulator body, which is achieved through the following technical solution:

[0024] A method for preparing an alumina-based ceramic insulator body includes the following steps:

[0025] Step 1: Synthesis of interface metal atom repair type alumina; simultaneously, preparation of sintering aids;

[0026] Step 2: Thoroughly mix the sintering aid and alumina aggregate prepared in Step 1 to obtain insulator mixed powder;

[0027] Step 3: Weigh 100 parts by weight of insulator mixed powder and 6-8 parts by weight of polyvinyl alcohol binder, mix and granulate to obtain spherical granules that pass through a 40-80 mesh sieve, place the spherical granules in a molding mold and perform isostatic pressing to obtain insulator blanks.

[0028] Step four: The insulator blank from step three is heated to 500-550℃ for 1-2 hours to remove glue, then heated to 1550-1750℃ for 2-6 hours to sinter, and finally cooled to room temperature and demolded to obtain the alumina-based ceramic insulator body.

[0029] The preparation method used in this invention is relatively simple, the process is mature, the production cost is relatively low, and it has strong scalability. Through large-scale production, the production cost of alumina-based ceramic insulators can be effectively reduced, and better market recognition and promotion can be achieved.

[0030] Preferably, in step four, the insulator blank from step three is placed in a discharge plasma sintering furnace, the vacuum degree is adjusted to ≤10Pa, the pressure is 6-9MPa, the temperature is first raised to 500-550℃ at a heating rate of 5-10℃ / min to remove the glue for 1-2 hours, then the temperature is raised to 1550-1750℃ at a heating rate of 30-50℃ / min to sinter for 2-6 hours, and finally the temperature is lowered to 800-850℃ at a heating rate of 5-10℃ / min, the furnace is opened and cooled to room temperature, and the alumina-based ceramic insulator body is obtained by demolding.

[0031] By adopting the above technical solutions, the overall dielectric and mechanical properties can be improved.

[0032] In summary, the present invention has the following advantages:

[0033] 1. This invention has the advantages of low dielectric constant and low dielectric loss, which meets the performance requirements of insulators for ultra-high voltage power transmission.

[0034] 2. By compounding sintering aids, this invention can improve the overall density, wear resistance, seismic performance, compressive strength and impact toughness of alumina ceramic insulators while ensuring their electrical performance, thereby better meeting the comprehensive performance requirements of insulators for ultra-high voltage power transmission and enhancing the market competitiveness of the products.

[0035] 3. The preparation method of the present invention is relatively simple, the process is mature, and it is easy to realize industrial-scale production and manufacturing. Detailed Implementation

[0036] To further understand the inventiveness and technical advancements of this invention, the preferred embodiments of this invention will be discussed in detail below with reference to examples and comparative examples.

[0037] Example: An alumina-based ceramic insulator body is made of interface-repairing alumina and a sintering aid, with a mass ratio of interface-repairing alumina to sintering aid of 100:(5-10). Preferably, the mass ratio of interface-repairing alumina to sintering aid is 100:(5-6). The sintering aid is at least one of zirconium oxide, rare earth oxides, calcium oxide, magnesium oxide, silicon dioxide, and manganese dioxide. Preferably, the sintering aid is composed of zirconium oxide, lanthanum oxide, cerium oxide, calcium oxide, magnesium oxide, and silicon dioxide. More preferably, the sintering aid is composed of the following raw materials in parts by weight: 100 parts zirconium oxide, 5-10 parts lanthanum oxide, 5-10 parts cerium oxide, 10-25 parts calcium oxide, 10-25 parts magnesium oxide, and 20-40 parts silicon dioxide.

[0038] Interface-repairing alumina is an interface-metal-atom-repairing alumina. Interface-metal-atom-repairing alumina includes a carrier alumina and metal atoms anchored in single-atom form at the defect sites of the carrier alumina. The metal atoms include at least Al.

[0039] The preparation method of interface metal atom repair type alumina is as follows:

[0040] Step 1: Prepare a modified acid solution with a mass concentration of 1-5%. The modified acid solution is prepared by water and organic acid. The water should be deionized water or pure water. The organic acid is at least one of tartaric acid, tannic acid, malic acid, citric acid, succinic acid, and oxalic acid. Place 10 parts by weight of alumina in 100-200 parts by weight of the modified acid solution and ultrasonically disperse for 4-8 hours. Dry to obtain organic acid modified alumina.

[0041] Step 2: Prepare a water-soluble metal salt solution with a concentration of 0.5-5 g / L. The water-soluble metal salt solution includes at least aluminum nitrate. Mix 10 parts by weight of organic acid-modified alumina with 50-1000 parts by weight of the water-soluble metal salt solution by mechanical stirring for 1-4 hours, ultrasonic dispersion for 1-4 hours, aging for 12-24 hours, and drying to obtain solid powder.

[0042] Step 3: The solid powder is ball-milled to refine it. The refined powder is then calcined in air at a temperature of 500-800℃ for 3-8 hours at a rate of 5-10℃ / min, followed by a temperature drop to 200-250℃ at a rate of 10-20℃ / min. The furnace is then allowed to cool naturally to room temperature. The resulting powder, after ball milling, yields a median diameter D. 50 Alumina with an interfacial metal atom thickness of 0.2-2.5 μm is used for interfacial metal atom repair.

[0043] Preferably, in step three, the solid powder is ball-milled to refine it. The refined powder is then calcined in air at a temperature of 600-650°C (8-10°C / min) for 4-6 hours, followed by a temperature drop to 200-250°C (20°C / min). The furnace is then allowed to cool naturally to room temperature. The resulting powder, after ball-milling, yields a median diameter D. 50 Alumina with an interfacial metal atom thickness of 0.2-2.5 μm is used for interfacial metal atom repair.

[0044] To optimize its electrical breakdown strength, the ceramic body of the alumina-based ceramic insulator is made of interface-repairing alumina, sintering aid, and fluorophlogopite powder. The mass ratio of interface-repairing alumina to sintering aid and fluorophlogopite powder is 100:(5-10):(5-10).

[0045] A method for preparing an alumina-based ceramic insulator body includes the following steps:

[0046] Step 1: Synthesis of interface metal atom repair type alumina; simultaneously, preparation of sintering aids;

[0047] Step 2: Thoroughly mix the sintering aid and alumina aggregate prepared in Step 1 to obtain insulator mixed powder;

[0048] Step 3: Weigh 100 parts by weight of insulator mixed powder and 6-8 parts by weight of polyvinyl alcohol binder, mix and granulate to obtain spherical granules that pass through a 40-80 mesh sieve, place the spherical granules in a molding mold and perform isostatic pressing to obtain insulator blanks.

[0049] Step 4: Place the insulator blank from Step 3 into a discharge plasma sintering furnace, adjust the vacuum degree to ≤10Pa and the pressure to 6-9MPa, first raise the temperature to 500-550℃ at a heating rate of 5-10℃ / min and remove the glue for 1-2 hours, then raise the temperature to 1550-1750℃ at a heating rate of 30-50℃ / min and sinter for 2-6 hours, finally lower the temperature to 800-850℃ at a heating rate of 5-10℃ / min, open the furnace and cool to room temperature, demold to obtain the alumina-based ceramic insulator body.

[0050] Preparation Example 1: The preparation method of interface metal atom repair type alumina is as follows:

[0051] Step 1: Prepare a modified acid solution with a mass concentration of 1.0%: Dissolve 10 parts by weight of tartaric acid in 990 parts by weight of pure water to form a modified acid solution with a mass concentration of 1.0%. Add 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D determined using an NS-90Plus nanoparticle size analyzer). 50 Tartaric acid-modified alumina was obtained by ultrasonic dispersion treatment for 8 hours in 100 parts by weight of modified acid solution (0.491 μm). The ultrasonic frequency was 40 kHz and the ultrasonic power was 800 W. After ultrasonic dispersion treatment, the mixture was filtered under reduced pressure. The obtained filter material was rinsed three times with pure water and vacuum dried to obtain tartaric acid-modified alumina.

[0052] Step 2: Prepare an aluminum nitrate aqueous solution with a concentration of 2 g / L. Mix 10 parts by weight of the organic acid-modified alumina from Step 1 with 100 parts by weight of the aluminum nitrate aqueous solution with a concentration of 2 g / L. Stir the mixture magnetically at 240 r / min for 4 h, then ultrasonically disperse it for 4 h at an ultrasonic frequency of 40 kHz and an ultrasonic power of 800 W. Aging is carried out for 16 h, followed by rotary evaporation drying to obtain a solid powder.

[0053] Step 3: The solid powder is placed in a planetary ball mill for dry ball milling to refine it. The grinding beads are zirconia, the ball milling speed is 200 rpm, and the ball milling time is 45 min. The median diameter D of the resulting refined powder is... 50 The median diameter (D) was 1.15 μm. The refined powder was calcined in air at 500 °C for 8 hours at a rate of 10 °C / min, then cooled to 200 °C at a rate of 15 °C / min. After cooling to room temperature, the powder was ball-milled. The resulting powder was then subjected to dry ball milling in a planetary ball mill with zirconia beads. The milling process was first coarse at 200 rpm for 20 minutes, followed by fine at 80 rpm for 40 minutes to obtain the median diameter (D). 50 Alumina with an interfacial metal atom thickness of 1.19 μm is used for interfacial metal atom repair.

[0054] The difference between Preparation Example 2 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 3.0%: Dissolving 30 parts by weight of tartaric acid in 970 parts by weight of pure water to form a modified acid solution with a mass concentration of 3.0%; adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D measured using an NS-90Plus nanoparticle size analyzer). 50 Tartaric acid-modified alumina (0.491 μm) was ultrasonically dispersed in 100 parts by weight of modified acid solution for 8 hours at an ultrasonic frequency of 40 kHz and an ultrasonic power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure. The resulting filter media was washed three times with pure water and vacuum dried to obtain tartaric acid-modified alumina. The remaining steps were the same to obtain the median diameter D. 50Alumina with an interfacial metal atom thickness of 1.22 μm is used for interfacial metal atom repair.

[0055] The difference between Preparation Example 3 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 5.0%: Dissolving 50 parts by weight of tartaric acid in 950 parts by weight of pure water to form a modified acid solution with a mass concentration of 5.0%, and adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D measured using an NS-90Plus nanoparticle size analyzer). 50 Tartaric acid-modified alumina (0.491 μm) was ultrasonically dispersed in 100 parts by weight of modified acid solution for 8 hours at an ultrasonic frequency of 40 kHz and an ultrasonic power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure. The resulting filter media was washed three times with pure water and vacuum dried to obtain tartaric acid-modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.26 μm is used for interfacial metal atom repair.

[0056] The difference between Preparation Example 4 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 0.25%: Dissolving 2.5 parts by weight of tartaric acid in 997.5 parts by weight of pure water to form a modified acid solution with a mass concentration of 0.25%; adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D measured using an NS-90Plus nanoparticle size analyzer). 50 Tartaric acid-modified alumina (0.491 μm) was ultrasonically dispersed in 100 parts by weight of modified acid solution for 8 hours at an ultrasonic frequency of 40 kHz and an ultrasonic power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure. The resulting filter media was washed three times with pure water and vacuum dried to obtain tartaric acid-modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.16 μm is used for interfacial metal atom repair.

[0057] The difference between Preparation Example 5 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 8.0%: Dissolving 80 parts by weight of tartaric acid in 920 parts by weight of pure water to form a modified acid solution with a mass concentration of 8.0%; adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D measured using an NS-90Plus nanoparticle size analyzer). 50 Tartaric acid-modified alumina (0.491 μm) was ultrasonically dispersed in 100 parts by weight of modified acid solution for 8 hours at an ultrasonic frequency of 40 kHz and an ultrasonic power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure. The resulting filter media was washed three times with pure water and vacuum dried to obtain tartaric acid-modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.35 μm is used for interfacial metal atom repair.

[0058] The difference between Preparation Example 6 and Preparation Example 1 is as follows: In step one, 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D measured using an NS-90Plus nanoparticle size analyzer) was used. 50 The alumina (0.491 μm) was ultrasonically dispersed in 100 parts by weight of pure water for 8 hours at an ultrasonic frequency of 40 kHz and an ultrasonic power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure. The resulting filter media was rinsed three times with pure water and vacuum dried to obtain tartaric acid-modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.15 μm is used for interfacial metal atom repair.

[0059] Example 1: An alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0060] Zirconia (XT-ZR02-02, 50nm), magnesium oxide (XT-MG0-02, 40nm), cerium oxide (XT-Ce02-02, 50nm), lanthanum oxide (XT-La2O3-01, 50nm), and silicon dioxide (XT-S102-02, 50nm) were supplied by Shanghai Xiangtian Nanomaterials Co., Ltd. Calcium oxide (DK-CaO-100) was supplied by Beijing Deco Island Gold Technology Co., Ltd., with a product specification of 100nm.

[0061] A method for preparing an alumina-based ceramic insulator body includes the following steps:

[0062] Step 1, the synthesis of interface metal atom repair type alumina is described in Preparation Example 1;

[0063] Simultaneously, the sintering aid is prepared by placing 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide in a dispersion vessel and mixing and dispersing at 400 rpm for 4 hours.

[0064] Step 2: Mix and disperse 10 parts by weight of the sintering aid prepared in Step 1 and 100 parts by weight of the alumina aggregate in Preparation Example 1 in a dispersion vessel at 400 rpm for 4 hours to obtain the insulator mixed powder.

[0065] Step 3: Weigh 100 parts by weight of insulator mixed powder and 7 parts by weight of polyvinyl alcohol binder, mix and granulate. The resulting granules are sieved through a 60-mesh sieve to obtain spherical granules. Place the spherical granules in a molding mold and press them at 120 MPa for 15 seconds. After the isostatic pressing is completed, demold to obtain insulator blanks.

[0066] Step four: Place the insulator blank from step three into a spark plasma sintering furnace for SPS sintering. Evacuate the spark plasma sintering furnace and control the vacuum degree inside the furnace to ≤10Pa and the pressure to 8MPa. First, heat the furnace at a rate of 10℃ / min to 550℃ and remove the adhesive for 80min. Then, heat the furnace at a rate of 50℃ / min to 1600℃ and sinter for 3h. Finally, cool the furnace at a rate of 10℃ / min to 850℃, open the furnace, cool to room temperature, and demold to obtain the alumina-based ceramic insulator body.

[0067] The difference between Example 2 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina in Preparation Example 2, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0068] The difference between Example 3 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina in Preparation Example 3, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0069] The difference between Example 4 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 1 part of silicon dioxide.

[0070] The difference between Example 5 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 3 parts of silicon dioxide.

[0071] The difference between Comparative Example 1 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 4, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 3 parts of silicon dioxide.

[0072] The difference between Comparative Example 2 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 5, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 3 parts of silicon dioxide.

[0073] The difference between Comparative Example 3 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 6, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 3 parts of silicon dioxide.

[0074] The difference between Comparative Example 4 and Example 1 is that the alumina-based ceramic insulator body is made from the following parts by weight of raw materials: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 1 part of calcium oxide, and 1 part of magnesium oxide.

[0075] The difference between Comparative Example 5 and Example 4 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, and 1 part of magnesium oxide.

[0076] Performance testing: 1. Impact toughness was determined according to GB / T44304-2024 "Test Method for Resistance to Fracture at Room Temperature of Fine Ceramics - Indentation (IF) Method". 2. Tensile strength was determined according to GB / T23805-2009 "Test Method for Tensile Strength of Fine Ceramics at Room Temperature". 3. Dielectric constant was determined using an HCWP-1000 dielectric temperature spectrometer at 1MHz and 25℃. 4. Breakdown strength was determined according to GB / T1408.1-20069 "Test Method for Electrical Strength of Insulating Materials".

[0077] Table 1: Test parameters of alumina-based ceramic insulators in Examples 1-5 and Comparative Examples 1-5

[0078] Density % Tensile strength (MPa) <![CDATA[Impact toughness MPa·m 0.5 > Breakdown strength kV / mm Dielectric constant Example 1 98.58 256.2 7.81 14.2 8.31 Example 2 98.71 258.5 7.85 14.3 8.24 Example 3 98.76 259.1 7.86 14.3 8.19 Example 4 98.24 250.6 7.52 14.1 8.35 Example 5 98.81 262.5 7.91 14.5 8.16 Comparative Example 1 98.17 239.6 6.74 13.8 9.17 Comparative Example 2 98.81 259.8 7.88 14.4 8.16 Comparative Example 3 98.02 236.5 6.46 13.2 9.64 Comparative Example 4 97.05 204.9 5.41 12.5 8.86 Comparative Example 5 97.68 229.4 5.87 12.8 8.62

[0079] Combining Examples 1-3 and Comparative Examples 1-3 with Table 1, it can be seen that the interface-repairing alumina synthesized by modifying alumina with a modified acid solution at a mass concentration of 1-5% has relatively fewer surface defects. The sintering density of the prepared alumina-based ceramic insulator is ≥98%, and the impact toughness is ≥7.5 MPa·m. 0.5The breakdown strength is ≥14.0kV / mm, and the dielectric constant decreases from 9.64 to 8.19-8.31, effectively improving the overall dielectric constant and dielectric loss while maintaining good mechanical properties.

[0080] Based on Examples 1, 4-5, and Comparative Examples 4-5, and in conjunction with Table 1, it can be seen that lanthanum oxide and cerium oxide, as sintering aids, are beneficial for improving the electrical and mechanical properties of alumina-based ceramic insulators. Furthermore, silica, as a sintering aid, is also beneficial for improving the electrical and mechanical properties of alumina-based ceramic insulators. In summary, the sintering aid formed by the compounding of zirconium oxide, lanthanum oxide, cerium oxide, calcium oxide, magnesium oxide, and silica can improve the electrical and mechanical properties of alumina-based ceramic insulators, better meeting the electrical performance requirements of insulators for ultra-high voltage power transmission.

[0081] The difference between Preparation Example 7 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 3.0%: Dissolving 15 parts by weight of tartaric acid and 15 parts by weight of citric acid in 970 parts by weight of pure water to form a modified acid solution with a mass concentration of 3.0%. Adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D determined using an NS-90Plus nanoparticle size analyzer). 50 Alumina with a median diameter of 0.491 μm was placed in 100 parts by weight of modified acid solution and ultrasonically dispersed for 8 hours at a frequency of 40 kHz and a power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure, and the resulting filter material was washed three times with pure water and vacuum dried to obtain tartaric acid + citric acid modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.24 μm is used for interfacial metal atom repair.

[0082] The difference between Preparation Example 8 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 3.0%: Dissolving 15 parts by weight of tartaric acid and 15 parts by weight of malic acid in 970 parts by weight of pure water to form a modified acid solution with a mass concentration of 3.0%. Adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D determined using an NS-90Plus nanoparticle size analyzer). 50 Alumina with a median diameter of 0.491 μm was placed in 100 parts by weight of modified acid solution and ultrasonically dispersed for 8 hours at a frequency of 40 kHz and a power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure, and the resulting filter material was washed three times with pure water and vacuum dried to obtain tartaric acid + malic acid modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.32 μm is used for interfacial metal atom repair.

[0083] The difference between Preparation Example 9 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 3.0%: Dissolving 15 parts by weight of tartaric acid and 15 parts by weight of tannic acid in 970 parts by weight of pure water to form a modified acid solution with a mass concentration of 3.0%. Adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D determined using an NS-90Plus nanoparticle size analyzer). 50 Alumina with a median diameter of 0.491 μm was placed in 100 parts by weight of modified acid solution and ultrasonically dispersed for 8 hours at a frequency of 40 kHz and a power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure. The resulting filter media was washed three times with pure water and vacuum dried to obtain tartaric acid + tannic acid modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.35 μm is used for interfacial metal atom repair.

[0084] The difference between Preparation Example 10 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 3.0%: Dissolving 15 parts by weight of malic acid and 15 parts by weight of tannic acid in 970 parts by weight of pure water to form a modified acid solution with a mass concentration of 3.0%. Adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D determined using an NS-90Plus nanoparticle size analyzer). 50 Alumina with a median diameter of 0.491 μm was placed in 100 parts by weight of modified acid solution and ultrasonically dispersed for 8 hours at a frequency of 40 kHz and a power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure. The resulting filter material was washed three times with pure water and vacuum dried to obtain malic acid + tannic acid modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.29 μm is used for interfacial metal atom repair.

[0085] The difference between Preparation Example 11 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 3.0%: Dissolving 15 parts by weight of citric acid and 15 parts by weight of tannic acid in 970 parts by weight of pure water to form a modified acid solution with a mass concentration of 3.0%; adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D determined using an NS-90Plus nanoparticle size analyzer). 50 Alumina with a median diameter of 0.491 μm was placed in 100 parts by weight of modified acid solution and ultrasonically dispersed for 8 hours at a frequency of 40 kHz and a power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure, and the resulting filter material was washed three times with pure water and vacuum dried to obtain citric acid + tannic acid modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.28 μm is used for interfacial metal atom repair.

[0086] The difference between Preparation Example 12 and Preparation Example 1 is as follows: Step 1, preparing a modified acid solution with a mass concentration of 3.0%: Dissolving 10 parts by weight of citric acid, 10 parts by weight of malic acid, and 10 parts by weight of tannic acid in 970 parts by weight of pure water to form a modified acid solution with a mass concentration of 3.0%. Adding 10 parts by weight of alumina (provided by Suzhou Beike Nanotechnology Co., Ltd., specification 500nm, median diameter D measured using an NS-90Plus nanoparticle size analyzer). 50 Alumina with a median diameter of 0.491 μm was placed in 100 parts by weight of modified acid solution and ultrasonically dispersed for 8 hours at a frequency of 40 kHz and a power of 800 W. After ultrasonic dispersion, the mixture was filtered under reduced pressure, and the resulting filter material was washed three times with pure water and vacuum dried to obtain tartaric acid + citric acid + tannic acid modified alumina. The remaining steps were the same to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.21 μm is used for interfacial metal atom repair.

[0087] The difference between Example 6 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 7, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0088] The difference between Example 7 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 8, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0089] The difference between Example 8 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 9, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0090] The difference between Example 9 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 10, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0091] The difference between Example 10 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 11, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0092] The difference between Example 11 and Example 1 is that the alumina-based ceramic insulator body is made from the following parts by weight of raw materials: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 12, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0093] Table 2: Test parameters of alumina-based ceramic insulators in Examples 1 and 6-11

[0094]

[0095]

[0096] Combining Examples 1 and 6-11 with Table 2, it can be seen that the interface-repairing alumina synthesized by modifying alumina with an organic acid solution formed by citric acid and tannic acid in a mass ratio of 1:1 can better repair alumina surface defects. The prepared alumina-based ceramic insulator has the best density, and its electrical and mechanical properties are also relatively optimal.

[0097] The difference between Preparation Example 13 and Preparation Example 1 is as follows: In step two, a 2 g / L aluminum nitrate aqueous solution was prepared. 10 parts by weight of the organic acid-modified alumina from step one were mixed with 50 parts by weight of the 2 g / L aluminum nitrate aqueous solution. The mixture was magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at a frequency of 40 kHz and a power of 800 W, and aged for 16 h. Subsequently, the mixture was rotary dried to obtain a solid powder. The remaining steps were the same, yielding a median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.16 μm is used for interfacial metal atom repair.

[0098] The difference between Preparation Example 14 and Preparation Example 1 is as follows: In step two, a 2 g / L aluminum nitrate aqueous solution is prepared. 10 parts by weight of the organic acid-modified alumina from step one is mixed with 200 parts by weight of the 2 g / L aluminum nitrate aqueous solution. The mixture is magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at a frequency of 40 kHz and a power of 800 W, and aged for 16 h. Subsequently, it is rotary dried to obtain a solid powder. The remaining steps are the same, yielding a median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.25 μm is used for interfacial metal atom repair.

[0099] The difference between Preparation Example 15 and Preparation Example 1 is as follows: In step two, a 2 g / L aluminum nitrate aqueous solution was prepared. 10 parts by weight of the organic acid-modified alumina from step one were mixed with 400 parts by weight of the 2 g / L aluminum nitrate aqueous solution. The mixture was magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at a frequency of 40 kHz and a power of 800 W, and aged for 16 h. Subsequently, the mixture was rotary dried to obtain a solid powder. The remaining steps were the same, yielding a median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.28 μm is used for interfacial metal atom repair.

[0100] The difference between Preparation Example 16 and Preparation Example 1 is as follows: In step two, a 2 g / L aluminum nitrate aqueous solution is prepared. 10 parts by weight of the organic acid-modified alumina from step one is mixed with 600 parts by weight of the 2 g / L aluminum nitrate aqueous solution. The mixture is magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at a frequency of 40 kHz and a power of 800 W, and aged for 16 h. Subsequently, it is rotary dried to obtain a solid powder. The remaining steps are the same, yielding a median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.29 μm is used for interfacial metal atom repair.

[0101] The difference between Preparation Example 17 and Preparation Example 1 is as follows: In step two, a 2 g / L aluminum nitrate aqueous solution is prepared. 10 parts by weight of the organic acid-modified alumina from step one is mixed with 800 parts by weight of the 2 g / L aluminum nitrate aqueous solution. The mixture is magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at a frequency of 40 kHz and a power of 800 W, and aged for 16 h. Subsequently, it is rotary dried to obtain a solid powder. The remaining steps are the same, yielding a median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.27 μm is used for interfacial metal atom repair.

[0102] The difference between Preparation Example 18 and Preparation Example 1 is as follows: In step two, a 2 g / L aluminum nitrate aqueous solution is prepared. 10 parts by weight of the organic acid-modified alumina from step one is mixed with 1000 parts by weight of the 2 g / L aluminum nitrate aqueous solution. The mixture is magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at a frequency of 40 kHz and a power of 800 W, and aged for 16 h. Subsequently, it is rotary dried to obtain a solid powder. The remaining steps are the same, yielding a median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.31 μm is used for interfacial metal atom repair.

[0103] The difference between Preparation Example 19 and Preparation Example 1 is as follows: In step two, a 2 g / L aluminum nitrate aqueous solution is prepared. 10 parts by weight of the organic acid-modified alumina from step one is mixed with 40 parts by weight of the 2 g / L aluminum nitrate aqueous solution. The mixture is magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at a frequency of 40 kHz and a power of 800 W, and aged for 16 h. Subsequently, it is rotary dried to obtain a solid powder. The remaining steps are the same, yielding a median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.31 μm is used for interfacial metal atom repair.

[0104] The difference between Preparation Example 20 and Preparation Example 1 is as follows: In step two, a 2 g / L aluminum nitrate aqueous solution was prepared. 10 parts by weight of the organic acid-modified alumina from step one were mixed with 1100 parts by weight of the 2 g / L aluminum nitrate aqueous solution. The mixture was magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at a frequency of 40 kHz and a power of 800 W, and aged for 16 h. Subsequently, the mixture was rotary dried to obtain a solid powder. The remaining steps were the same, yielding a median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.31 μm is used for interfacial metal atom repair.

[0105] The difference between Preparation Example 21 and Preparation Example 1 is as follows: In step two, 10 parts by weight of the organic acid-modified alumina from step one are mixed with 100 parts by weight of pure water, magnetically stirred at 240 r / min for 4 h, ultrasonically dispersed for 4 h at an ultrasonic frequency of 40 kHz and an ultrasonic power of 800 W, aged for 16 h, and then rotary dried to obtain a solid powder. The remaining steps are the same, and the median diameter D is obtained. 50 It is 1.04 μm aluminum oxide.

[0106] The difference between Example 12 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 13, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0107] The difference between Example 13 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 14, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0108] The difference between Example 14 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 15, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0109] The difference between Example 15 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 16, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0110] The difference between Example 16 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 17, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0111] The difference between Example 17 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 18, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0112] The difference between Comparative Example 4 and Example 1 is that the alumina-based ceramic insulator body is made from the following parts by weight of raw materials: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 19, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0113] The difference between Comparative Example 5 and Example 1 is that the alumina-based ceramic insulator body is made from the following parts by weight of raw materials: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 20, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0114] The difference between Comparative Example 6 and Example 1 is that the alumina-based ceramic insulator body is made from the following parts by weight of raw materials: 100 parts by weight of alumina from Preparation Example 21, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0115] Table 3: Test parameters of alumina-based ceramic insulators in Examples 1, 12-17 and Comparative Examples 4-6

[0116] Density % Tensile strength (MPa) <![CDATA[Impact resistance toughness MPa·m 0.5 > Breakdown strength kV / mm Dielectric Basics Example 1 98.58 256.2 7.81 14.2 8.31 Example 12 98.49 254.6 7.74 14.2 8.34 Example 13 98.66 258.8 7.88 14.4 8.23 Example 14 98.62 256.9 7.83 14.3 8.27 Example 15 98.41 252.4 7.65 14.1 8.39 Example 16 98.33 248.1 7.39 14.1 8.43 Example 17 98.29 245.3 7.26 14.0 8.49 Comparative Example 4 98.43 253.1 7.69 14.1 8.37 Comparative Example 5 97.82 236.9 6.76 13.6 8.74 Comparative Example 6 96.81 199.7 5.49 12.1 8.81

[0117] Based on Examples 1 and 7-11 and Table 1, it can be seen that the ratio of organic acid-modified alumina to a 2 g / L aluminum nitrate aqueous solution affects the degree of surface defect repair in the synthesized interface-repairing alumina. When the ratio of organic acid-modified alumina to a 2 g / L aluminum nitrate aqueous solution is controlled at 10:(50-1000), the alumina-based ceramic insulator body prepared using this interface-repairing alumina exhibits relatively good electrical and mechanical properties. Preferably, the ratio of organic acid-modified alumina to a 2 g / L aluminum nitrate aqueous solution is 10:(100-400).

[0118] The difference between Preparation Example 22 and Preparation Example 1 is that steps one and two are the same, but in step three, the solid powder is subjected to dry ball milling in a planetary ball mill for refining. The grinding beads are zirconium oxide, the ball milling speed is 200 rpm, and the ball milling time is 45 min. The median diameter D of the resulting refined powder is... 50 The median diameter (D) was 1.18 μm. The refined powder was calcined in air at 600 °C for 4.0 h at a rate of 10 °C / min, then cooled to 200 °C at a rate of 15 °C / min. After natural cooling to room temperature, the powder was ball-milled. The resulting powder was then subjected to dry ball milling in a planetary ball mill with zirconia beads. The milling process involved coarse grinding at 200 rpm for 20 min, followed by fine grinding at 80 rpm for 40 min to obtain the median diameter (D). 50 Alumina with an interfacial metal atom thickness of 1.24 μm is used for interfacial metal atom repair.

[0119] The difference between Preparation Example 23 and Preparation Example 1 is that steps one and two are the same, but in step three, the solid powder is subjected to dry ball milling in a planetary ball mill for refining. The grinding beads are zirconium oxide, the ball milling speed is 200 rpm, and the ball milling time is 45 min. The median diameter D of the resulting refined powder is... 50 The median diameter (D) was 1.15 μm. The refined powder was calcined in air at 600 °C for 6.0 h at a rate of 10 °C / min, then cooled to 200 °C at a rate of 15 °C / min. After cooling to room temperature, the powder was ball-milled. The resulting powder was then subjected to dry ball milling in a planetary ball mill with zirconia beads. The milling process was first coarse grinding at 200 rpm for 20 min, followed by fine grinding at 80 rpm for 40 min to obtain the median diameter (D). 50 Alumina with an interfacial metal atom thickness of 1.26 μm is used for interfacial metal atom repair.

[0120] The difference between Preparation Example 24 and Preparation Example 1 is that steps one and two are the same, but in step three, the solid powder is subjected to dry ball milling in a planetary ball mill for refining. The grinding beads are zirconium oxide, the ball milling speed is 200 rpm, and the ball milling time is 45 min. The median diameter D of the resulting refined powder is... 50 The median diameter (D) was 1.13 μm. The refined powder was calcined in air at 650 °C for 5.0 h at a rate of 10 °C / min, then cooled to 200 °C at a rate of 15 °C / min. After cooling to room temperature, the powder was ball-milled. The resulting powder was then subjected to dry ball milling in a planetary ball mill with zirconia beads. The milling process involved coarse grinding at 200 rpm for 20 min, followed by fine grinding at 80 rpm for 40 min to obtain the median diameter (D). 50 Alumina with an interfacial metal atom thickness of 1.21 μm is used for interfacial metal atom repair.

[0121] The difference between Preparation Example 25 and Preparation Example 1 is that steps one and two are the same, but in step three, the solid powder is subjected to dry ball milling in a planetary ball mill for refining. The grinding beads are zirconium oxide, the ball milling speed is 200 rpm, and the ball milling time is 45 min. The median diameter D of the resulting refined powder is... 50 The median diameter D was 1.20 μm. The refined powder was calcined in air at 700 °C for 4.0 h at a rate of 10 °C / min, then cooled to 200 °C at a rate of 15 °C / min. After cooling to room temperature, the powder was ball-milled. The resulting powder was then subjected to dry ball milling in a planetary ball mill with zirconia beads. The milling process was first coarse grinding at 200 rpm for 20 min, followed by fine grinding at 80 rpm for 40 min to obtain the median diameter D. 50 Alumina with an interfacial metal atom thickness of 1.32 μm is used for interfacial metal atom repair.

[0122] The difference between Preparation Example 26 and Preparation Example 1 is that steps one and two are the same, but in step three, the solid powder is subjected to dry ball milling in a planetary ball mill for refining. The grinding beads are zirconium oxide, the ball milling speed is 200 rpm, and the ball milling time is 45 min. The median diameter D of the resulting refined powder is... 50 The median diameter (D) was 1.15 μm. The refined powder was calcined in air at 800 °C for 3.0 h at a rate of 10 °C / min, then cooled to 200 °C at a rate of 15 °C / min. After cooling to room temperature, the powder was ball-milled. The resulting powder was then subjected to dry ball milling in a planetary ball mill with zirconia beads. The milling process involved coarse grinding at 200 rpm for 20 min, followed by fine grinding at 80 rpm for 40 min to obtain the median diameter (D). 50 Alumina with an interfacial metal atom thickness of 1.35 μm is used for interfacial metal atom repair.

[0123] The difference between Example 18 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 22, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0124] The difference between Example 19 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 23, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0125] The difference between Example 20 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 24, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0126] The difference between Example 21 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 25, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0127] The difference between Example 22 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 26, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, and 2 parts of silicon dioxide.

[0128] Table 4: Test parameters of alumina-based ceramic insulators in Examples 1 and 18-22

[0129] Density % Tensile strength (MPa) <![CDATA[Impact toughness MPa·m 0.5 > Breakdown strength kV / mm Dielectric Basics Example 1 98.58 256.2 7.81 14.2 8.31 Example 18 98.84 263.1 7.96 14.3 8.24 Example 19 99.08 267.2 8.03 14.4 8.19 Example 20 99.15 268.4 8.07 14.4 8.15 Example 21 98.69 258.1 7.92 14.3 8.26 Example 22 98.35 252.4 7.76 14.2 8.37

[0130] Based on Examples 1 and 18-22 and Table 4, it can be seen that the calcination temperature during the synthesis of interface-repairing alumina should be controlled at 600-650℃ and the calcination time should be controlled at 4-6h. Under the above synthesis conditions, the surface defects of the interface-repairing alumina are well repaired, which can ensure the electrical and mechanical properties of the alumina-based ceramic insulator.

[0131] The difference between Example 23 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, 2 parts of silicon dioxide, and 2.5 parts of fluorophlogopite powder. The fluorophlogopite powder was selected from Guangdong Yuanlei Powder Co., Ltd., with a particle size distribution of 0.73-2.6 μm and a median diameter D. 50 It is 1.08 μm.

[0132] The difference between Example 24 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, 2 parts of silicon dioxide, and 5 parts of fluorophlogopite powder.

[0133] The difference between Example 25 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, 2 parts of silicon dioxide, and 7.5 parts of fluorophlogopite powder.

[0134] The difference between Example 26 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, 2 parts of silicon dioxide, and 10 parts of fluorophlogopite powder.

[0135] The difference between Example 27 and Example 1 is that the alumina-based ceramic insulator body is made from the following raw materials in parts by weight: 100 parts by weight of the interface metal atom repair type alumina from Preparation Example 1, 5 parts of zirconium oxide, 0.5 parts of lanthanum oxide, 0.5 parts of cerium oxide, 1 part of calcium oxide, 1 part of magnesium oxide, 2 parts of silicon dioxide, and 12.5 parts of fluorophlogopite powder.

[0136] Table 5: Test parameters of alumina-based ceramic insulators in Examples 1 and 23-27

[0137] Density % Tensile strength (MPa) <![CDATA[Impact toughness MPa·m 0.5 > Breakdown strength kV / mm Dielectric Basics Example 1 98.58 256.2 7.81 14.2 8.31 Example 23 98.67 260.8 8.09 15.1 8.25 Example 24 98.72 265.1 8.21 16.2 8.13 Example 25 98.65 272.4 8.32 16.9 8.03 Example 26 98.55 275.9 8.38 17.3 7.96 Example 27 98.43 279.4 8.42 17.5 7.92

[0138] As can be seen from Examples 1 and 23-27, and Table 5, the addition of fluorophlogopite powder can improve the breakdown strength of alumina-based ceramic insulators while enhancing their electrical and mechanical properties. Given that the content of interface metal atom-repairing alumina is 100 parts by weight, the preferred addition amount of fluorophlogopite powder is 5-10 parts.

[0139] In summary, this invention repairs defects on the surface of calcined alumina with single-atom aluminum, which compensates for oxygen vacancies generated during calcination through covalent bonds. This effectively reduces the dielectric constant and dielectric loss of the alumina-based ceramic insulator while giving it good anti-fouling, antibacterial, and hygienic safety properties, meeting the electrical performance requirements of insulators for ultra-high voltage power transmission.

[0140] It should be noted that this specific embodiment is merely an explanation of the technical solution of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. An alumina-based porcelain insulator body, characterized by: The alumina-based ceramic insulator body is made using interface-repairing alumina and sintering aids, with a mass ratio of interface-repairing alumina to sintering aids of 100:(5-10); the sintering aids are at least one of zirconium oxide, rare earth oxides, calcium oxide, magnesium oxide, silicon dioxide, and manganese dioxide; the interface-repairing alumina is an interface metal atom-repairing alumina, which includes a carrier alumina and metal atoms anchored to the defect sites of the carrier alumina in the form of single atoms, the metal atoms including at least Al.

2. The porcelain body of claim 1, wherein: The preparation method of the interface metal atom repair type alumina is as follows: Step 1: Prepare a modified acid solution with a mass concentration of 1-5%. Place 10 parts by weight of alumina in 100-200 parts by weight of the modified acid solution and ultrasonically disperse for 4-8 hours. Dry to obtain organic acid modified alumina. Step 2: Prepare a water-soluble metal salt solution with a concentration of 0.5-5 g / L. The water-soluble metal salt solution includes at least aluminum nitrate. Mix 10 parts by weight of organic acid-modified alumina with 50-1000 parts by weight of the water-soluble metal salt solution by mechanical stirring for 1-4 hours, ultrasonic dispersion for 1-4 hours, aging for 12-24 hours, and drying to obtain solid powder. Step 3: The solid powder is ball-milled to refine it. The refined powder is then calcined in air at a temperature of 500-800℃ for 3-8 hours at a rate of 5-10℃ / min, followed by a temperature drop to 200-250℃ at a rate of 10-20℃ / min. The furnace is then allowed to cool naturally to room temperature. The resulting powder, after ball milling, yields a median diameter D. 50 Alumina with an interfacial metal atom thickness of 0.2-2.5 μm is used for interfacial metal atom repair.

3. An alumina based porcelain insulator body according to claim 2, characterised in that: The modified acid solution is prepared from water and organic acid, and the water is required to be deionized water or pure water; the organic acid is at least one of tartaric acid, tannic acid, malic acid, citric acid, succinic acid and oxalic acid.

4. The alumina-based porcelain body for a porcelain electrical insulator according to claim 3, characterized in that: The modified acid solution is made from pure water, tannic acid, and citric acid, with a mass ratio of tannic acid to citric acid of 1:

1.

5. The alumina-based porcelain body of claim 3, wherein: In step three, the solid powder is ball-milled to refine it. The refined powder is then calcined in air at a temperature of 600-650°C (8-10°C / min) for 4-6 hours, followed by a temperature drop to 200-250°C (20°C / min). The calcination process is then allowed to proceed naturally to room temperature. The resulting powder, after ball-milling, yields a median diameter D. 50 Alumina with an interfacial metal atom thickness of 0.2-2.5 μm is used for interfacial metal atom repair.

6. The alumina-based ceramic insulator body according to claim 5, characterized in that: The sintering aid is composed of zirconium oxide, lanthanum oxide, cerium oxide, calcium oxide, magnesium oxide, and silicon dioxide.

7. The alumina-based ceramic insulator body according to claim 6, characterized in that: The sintering aid is composed of the following raw materials in parts by weight: 100 parts zirconium oxide, 5-10 parts lanthanum oxide, 5-10 parts cerium oxide, 10-25 parts calcium oxide, 10-25 parts magnesium oxide, and 20-40 parts silicon dioxide.

8. An alumina based porcelain insulator body according to claim 7, characterized in that: The alumina-based ceramic insulator body is made of interface-repairing alumina, sintering aid, and fluorophlogopite powder, and the mass ratio of the interface-repairing alumina to the sintering aid and the fluorophlogopite powder is 100:(5-10):(5-10).

9. A process for the production of a porcelain body for an alumina based porcelain electrical insulator according to any one of claims 1 to 8, characterized in that: Includes the following steps: Step 1: Synthesis of interface metal atom repair type alumina; simultaneously, preparation of sintering aids; Step 2: Thoroughly mix the sintering aid and alumina aggregate prepared in Step 1 to obtain insulator mixed powder; Step 3: Weigh 100 parts by weight of insulator mixed powder and 6-8 parts by weight of polyvinyl alcohol binder, mix and granulate to obtain spherical granules that pass through a 40-80 mesh sieve, place the spherical granules in a molding mold and perform isostatic pressing to obtain insulator blanks. Step four: The insulator blank from step three is heated to 500-550℃ for 1-2 hours to remove glue, then heated to 1550-1750℃ for 2-6 hours to sinter, and finally cooled to room temperature and demolded to obtain the alumina-based ceramic insulator body.

10. The method for preparing an alumina-based ceramic insulator body according to claim 9, characterized in that: In step four, the insulator blank from step three is placed in a discharge plasma sintering furnace. The vacuum degree is adjusted to ≤10Pa and the pressure to 6-9MPa. The temperature is first raised to 500-550℃ at a heating rate of 5-10℃ / min for 1-2 hours to remove the adhesive. Then, the temperature is raised to 1550-1750℃ at a heating rate of 30-50℃ / min for 2-6 hours to sinter. Finally, the temperature is lowered to 800-850℃ at a heating rate of 5-10℃ / min. The furnace is then opened, cooled to room temperature, and demolded to obtain the alumina-based ceramic insulator body.

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