Anti-fracture high-toughness porcelain suspension insulator

Abstract

This invention relates to the field of ceramic technology, specifically to a fracture-resistant, high-toughness ceramic suspension insulator. The insulator comprises a ceramic component, an iron cap, and steel feet. The ceramic component includes a fired ceramic blank, a glaze layer on the surface of the glazed area of ​​the fired ceramic blank, and a boron-aluminum-silicon transition layer between the two. The boron-aluminum-silicon transition layer is formed by first spraying an uncomplexed, highly dispersed boehmite anchoring sol onto the glazed area of ​​the dried ceramic blank, followed by spraying a modified boron-aluminum-silicon transition sol containing tetraethyl orthosilicate, aluminum nitrate nonahydrate, boric acid, colloidal silica, citric acid-complexed highly dispersed boehmite, and polyethylene glycol. This process is followed by segmented drying, glazing, and firing. The average penetration depth of this transition layer in the surface of the fired ceramic blank is 90-120 μm. This structure can form a continuous, gradual interface between the glaze layer and the fired ceramic blank, reducing abrupt changes in thermal expansion and interfacial stress concentration, thereby improving the ceramic suspension insulator's resistance to thermal cycling cracking, electromechanical destructive loads, and electrical stability under artificial pollution conditions.

Description

Technical Field

[0001] This invention relates to the field of ceramic technology, and in particular to a fracture-resistant, high-toughness ceramic suspension insulator. Background Technology

[0002] As a critical component of the power system, the mechanical strength and crack resistance of porcelain suspension insulators directly affect the safe operation of the power grid. Traditional high-strength aluminum porcelain insulators typically enhance mechanical strength by increasing the overall alumina content or by adjusting the thermal expansion coefficient of the glaze to match the blank. However, these methods do not address the microstructural control of the interface between the glaze layer and the porcelain blank. In practical applications, insulators must withstand complex conditions such as thermal cycling and electromechanical tension. The interfacial stress caused by the difference in thermal expansion coefficients between the glaze layer and the blank tends to concentrate in the shallow surface area, forming microcracks that gradually propagate and eventually lead to fracture failure.

[0003] Existing improvement schemes mostly focus on overall performance enhancement, such as increasing the density of the ceramic body by increasing the corundum phase content or optimizing the firing curve to reduce internal defects. However, they pay insufficient attention to the structural continuity of the transition zone between the glaze layer and the body. When the insulator undergoes drastic temperature changes, the inconsistent shrinkage between the glaze layer and the body will generate shear stress at the interface. If there is a lack of a gradient transition structure, the stress cannot be effectively released, thus inducing circumferential cracks. In addition, in artificially polluted environments, the electric field distortion at the cracks will exacerbate leakage current and reduce electrical stability. These problems have not been effectively solved by existing overall optimization schemes, becoming a key bottleneck restricting the long-term reliable operation of ceramic suspension insulators. Summary of the Invention

[0004] In view of this, the purpose of this invention is to propose a fracture-resistant, high-toughness ceramic suspension insulator to solve the problem that the existing technology only optimizes the overall body composition, firing regime or glaze formula, without performing continuous transition treatment on the 90-120μm shallow surface area between the glaze layer and the ceramic body, which leads to abrupt changes in thermal expansion and firing shrinkage, easily causing circumferential microcracks and reducing the fracture resistance and electrical stability of the insulator.

[0005] To achieve the above objectives, the present invention provides a fracture-resistant, high-toughness ceramic suspension insulator, comprising a ceramic component, an iron cap, and a steel foot. The iron cap and the steel foot are respectively glued to both ends of the ceramic component using cement adhesive. The ceramic component comprises a fired ceramic blank, a glaze layer disposed on the surface of the glazed area of ​​the fired ceramic blank, and a boron-aluminum-silicon transition layer located between the fired ceramic blank and the glaze layer.

[0006] Furthermore, by mass fraction, the fired ceramic body is obtained by shaping and firing a ceramic body raw material comprising 850-950 parts reactive alumina powder, 900-1000 parts kaolin concentrate, 320-380 parts potassium feldspar powder, 220-280 parts fused silica powder, 1040-1160 parts deionized water, 4-6 parts sodium tripolyphosphate and 6-10 parts sodium carboxymethyl cellulose; Furthermore, the glaze layer is obtained by firing the glaze slurry of electric porcelain; the boron-aluminum-silicon transition layer is obtained by wetting the glazed area of ​​the porcelain blank after treatment with uncomplexed highly dispersed boehmite anchoring sol, followed by segmented drying, glazing, and firing with modified boron-aluminum-silicon transition sol, and the average wetting depth of the boron-aluminum-silicon transition layer in the unfired surface of the porcelain blank is 90-120 μm.

[0007] Furthermore, by mass fraction, the uncomplexed highly dispersed boehmite anchoring sol is prepared from 380-420 parts of deionized water, 3.5-4.5 parts of nitric acid with a mass fraction of 65%, 70-90 parts of anhydrous ethanol, and 26-34 parts of boehmite powder.

[0008] Furthermore, by mass parts, the modified boron-aluminum-silicon transition sol is prepared from 110-130 parts tetraethyl orthosilicate, 260-300 parts anhydrous ethanol, 110-130 parts deionized water, 4.5-5.5 parts nitric acid with a mass fraction of 65%, 210-230 parts deionized water, 185-215 parts aluminum nitrate nonahydrate, 18-26 parts boric acid, 110-130 parts colloidal silica, a citric acid complexed highly dispersed boehmite dispersion prepared from 45-55 parts deionized water, 8-12 parts citric acid monohydrate and 26-34 parts dispersible boehmite powder, 90-110 parts deionized water and 14-22 parts polyethylene glycol with a number average molecular weight of 20,000.

[0009] Furthermore, the reactive alumina powder has a median diameter of 300-500 nm and a specific surface area of ​​5-10 m². 2 / g; the kaolin concentrate is 325 mesh kaolin concentrate; the potassium feldspar powder is sieved through a 325 mesh sieve before use; the fused silica powder is 325 mesh fused silica powder.

[0010] Furthermore, the colloidal silica is an aqueous suspension with a mass fraction of 30%; the alumina content of the boehmite powder and the dispersible boehmite powder is 72%, and the water-dispersed particle size is 20-30 nm.

[0011] Furthermore, by mass, the electrical porcelain glaze slurry is prepared from 360-400 parts potassium feldspar powder, 280-320 parts fused silica powder, 110-130 parts kaolin concentrate, 70-90 parts calcite powder, 50-70 parts talc powder, 35-45 parts reactive alumina powder, 15-25 parts iron oxide brown pigment, 520-580 parts deionized water, and 2.5-3.5 parts sodium tripolyphosphate.

[0012] Furthermore, by weight, the cementitious binder is prepared from 500 parts silicate cement, 150 parts refined quartz sand and 180 parts deionized water.

[0013] Furthermore, the porcelain suspension insulator is a 120kN disc-shaped porcelain suspension insulator, the iron cap and the steel foot are 120kN ball-and-socket connectors, and the exposed glazed area of ​​the porcelain component is 2000-2500 cm². 2 .

[0014] Furthermore, the exposed glazed area of ​​the porcelain piece is 2300 cm². 2 The amount of the uncomplexed highly dispersed boehmite anchoring sol to be sprayed is 18-22g, the nozzle diameter is 1mm, the spraying pressure is 0.25MPa, the nozzle of the spray gun is 20cm away from the surface of the ceramic blank, the ceramic blank is rotated at 20r / min, after spraying the ceramic blank is placed at 35℃ for 15-25min, and then dried at 55-65℃ for 25-35min.

[0015] Furthermore, the exposed glazed area of ​​the porcelain piece is 2300 cm². 2 The modified boron-aluminum-silicon transition sol is sprayed twice onto the glazed area of ​​the ceramic blank after treatment with uncomplexed highly dispersed boehmite anchoring sol. The first spray is 28-32g, and the blank is left at 25℃ for 8-10 minutes after spraying. The second spray is 24-28g, and the blank is left at 25℃ for 10-14 minutes after spraying.

[0016] Furthermore, the segmented drying process involves drying at 38-42℃ for 25-35 minutes, at 70-80℃ for 80-100 minutes, and at 105-115℃ for 50-70 minutes in sequence.

[0017] Furthermore, the glazing and firing process involves: spraying an electric porcelain glaze slurry onto the glazing area of ​​the porcelain blank and drying it to obtain a glazed porcelain blank; and firing the glazed porcelain blank to obtain a fired porcelain piece.

[0018] Furthermore, the exposed glazed area of ​​the porcelain piece is 2300 cm². 2The amount of the glaze slurry applied is 230-250g, the spraying pressure is 0.25MPa, the nozzle diameter is 1mm, the distance between the spray gun outlet and the surface of the ceramic blank is 20cm, the ceramic blank is rotated at 20r / min, and after spraying, it is dried at 80℃ for 120min; the firing process is as follows: the glazed ceramic blank is placed in the electric porcelain firing kiln, and the temperature is raised from 25℃ to 200℃ in an oxidizing atmosphere at a heating rate of 30℃ / h, and held for 2h. Continue heating to 600℃ at a rate of 60℃ / h and hold for 2 hours; continue heating to 980℃ at a rate of 90℃ / h and hold for 1 hour; continue heating to 1260℃ to 1300℃ at a rate of 70℃ / h and hold for 2.5 to 3.5 hours; then reduce to 1000℃ at a rate of 60℃ / h and hold for 1 hour; then reduce to 600℃ at a rate of 80℃ / h, and then cool with the kiln to below 80℃ before exiting the kiln.

[0019] The beneficial effects of this invention are: (1) This invention utilizes the synergistic effect of uncomplexed highly dispersed boehmite anchoring sol and modified boron-aluminum-silica transition sol to form a continuous transition layer of 90-120 μm on the surface of the ceramic body, thereby reducing the difference in linear expansion between the glaze layer, the shallow ceramic body, and the internal body to 0.16 × 10⁻⁶. -6 K -1 (Example 3) The transition interface continuity reaches 100%, effectively mitigating abrupt thermal expansion and interface stress concentration. Data shows that after thermal cycling in Example 3, the number of circumferential cracks is 0. -1 Comparison Example 1 (3.2 items) -1 The significant reduction in [something] demonstrates the inhibitory effect of the transition layer on microcrack propagation.

[0020] (2) This invention employs a segmented drying and two-stage spraying process, combined with the gate effect of polyethylene glycol 20000, to control the uniform wetting and distribution of the sol in the shallow layer of the ceramic blank. Example 3: Room temperature flexural strength reached 187.3 MPa, and fracture toughness reached 2.91 MPa·m. 1 / 2 After thermal cycling, the electromechanical failure load increased to 178.6 kN, a 36.4% increase compared to Comparative Example 7 (130.8 kN), achieving a synergistic improvement in both toughness and fracture resistance. Meanwhile, under artificial pollution conditions, the flashover voltage reached 55.36 kV, and the peak leakage current was only 12.84 mA, ensuring electrical stability.

[0021] (3) This invention does not simply add a coating layer to the surface of the ceramic body. Instead, it pre-anchors the shallow pores of the dried ceramic body using an uncomplexed, highly dispersed boehmite anchoring sol, and then uses a modified boron-aluminum-silicon transition sol containing citric acid-complexed highly dispersed boehmite, boron source, aluminum source, and silicon source for controlled wetting, so that a continuous boron-aluminum-silicon transition layer is formed between the glaze layer and the fired ceramic body after firing. This transition layer is different from the external low thermal expansion underlayer. Part of it is located in the shallow surface layer of the fired ceramic body, and forms a gradient distribution of Al, Si, and B elements along the direction from the glaze layer to the body, thereby reducing the abrupt changes in thermal expansion and firing shrinkage between the glaze layer and the fired ceramic body. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0023] The reactive alumina powder used in the specific implementation method is Almatis CT3000SG reactive alumina powder, with a median diameter of approximately 400 nm and a specific surface area of ​​approximately 8 m². 2 / g; Kaolin is 325 mesh kaolin concentrate from Longyan Kaolin Co., Ltd.; Potassium feldspar powder is feldspar powder from Daye Jinpeng Friction Materials Co., Ltd., sieved through a 325 mesh sieve before use; Fused silica powder is Grade I 325 mesh fused silica powder from Xinyi Jiaxin Mining Co., Ltd.; Colloidal silica is Sigma-Aldrich 420883, 30% by mass aqueous suspension; Boehmite powder is Sasol DISPERAL. P2 high-purity dispersible boehmite powder, alumina content 72%, water-dispersible particle size approximately 25nm; polyethylene glycol is Sigma-Aldrich 81300, number average molecular weight 20000, flaky solid; calcite powder is calcite powder from Daye Jinpeng Friction Materials Co., Ltd., sieved through a 325-mesh sieve before use; talc powder is Shanghai Aladdin Biochemical Technology Co., Ltd. T109493 talc powder, pharmaceutical grade, not less than 325 mesh; iron oxide brown material is Toda United Industrial (Zhejiang) Co., Ltd. UZ610 iron oxide brown; refined quartz sand is 20-40 mesh refined quartz sand from Xinyi Jiaxin Mining Co., Ltd.; silicate cement is Conch brand P.O42.5 ordinary silicate cement; iron caps and steel feet are commercially available 120kN ball-and-socket connectors conforming to GB / T7253-2019.

[0024] Example 1: Step 1: Add 900g reactive alumina powder, 950g kaolin concentrate, 350g potassium feldspar powder, 250g fused silica powder, 1100g deionized water, 5g sodium tripolyphosphate, and 8g sodium carboxymethyl cellulose to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2 and ball mill at 250r / min for 18h. After ball milling, pass the slurry through a 325-mesh sieve. Degas the sieved slurry under a vacuum of -90kPa for 20min, filter until the moisture content is 18.5%, and vacuum knead the slurry three times. Then, place it into a disc-shaped suspension porcelain insulator metal mold and press it at 25MPa for 3min. After demolding, the exposed glazed area is 2300cm². 2 The wet blank of the disc-shaped suspension porcelain insulator; Step 2: Dry the wet blank of the disc suspension porcelain insulator obtained in Step 1 at 45℃ for 8 hours, and then turn it to trim the blank according to the shape of the 120kN disc suspension porcelain insulator; dry the trimmed porcelain blank at 80℃ for 6 hours, and then at 110℃ for 6 hours. Measure the moisture content of the porcelain blank by the 105℃ weight loss method. The moisture content should not be higher than 1%, and the dried porcelain blank is obtained. Step 3: Place 400g of deionized water in a glass container, and slowly add 4g of 65% nitric acid at 25℃ and 300r / min with stirring, and stir for 10min; then add 80g of anhydrous ethanol and stir for 10min; then add 30g of boehmite powder and stir at 25℃ and 600r / min for 60min to obtain uncomplexed highly dispersed boehmite anchoring sol; Step 4: Weigh 20g of the uncomplexed highly dispersed boehmite anchoring sol obtained in Step 3, and spray it onto the glazing area of ​​the dried ceramic blank obtained in Step 2 using a regular spray gun with a nozzle diameter of 1mm. The spraying pressure is 0.25MPa, the nozzle of the spray gun is 20cm away from the surface of the ceramic blank, and the ceramic blank is rotated at 20r / min. After spraying, place the ceramic blank at 35℃ for 20min, and then dry it at 60℃ for 30min to obtain a ceramic blank that has been anchored on the inside by uncomplexed highly dispersed boehmite powder. Step 5: Add 50g of deionized water, 10g of citric acid monohydrate and 30g of dispersible boehmite powder to a glass container and stir at 50℃ and 600r / min for 40min to obtain 90g of citric acid complexed highly dispersible boehmite dispersion. Step 6: Add 120g of tetraethyl orthosilicate to 280g of anhydrous ethanol and stir at 25℃ and 400r / min for 20min to obtain a tetraethyl orthosilicate ethanol solution; separately, mix 120g of deionized water and 5g of 65% nitric acid and cool to 25℃ to obtain an acid-water solution; under stirring conditions of 35℃ and 500r / min, add the acid-water solution dropwise to the tetraethyl orthosilicate ethanol solution over 30min, controlling the liquid temperature not to exceed 40℃ during the addition. After the addition is complete, continue stirring at 35℃ for 60min to obtain a hydrolyzed silica sol; add 220g of deionized water, 200g of aluminum nitrate nonahydrate, and 22g of boric acid to another glass... In a glass container, the mixture was stirred at 50°C and 500 rpm for 40 min to obtain a boron-aluminum aqueous solution. The boron-aluminum aqueous solution was added dropwise to the hydrolyzed silica sol over 60 min. After the addition was complete, the mixture was stirred at 35°C for 120 min. 120 g of colloidal silica was added over 20 min, and the mixture was stirred at 35°C for 60 min. Subsequently, 90 g of the citric acid complexed highly dispersed boehmite dispersion obtained in step 5 was added, and the mixture was stirred at 35°C for 60 min. Finally, 100 g of deionized water and 18 g of polyethylene glycol were dissolved at 60°C, cooled to 35°C, and added to the above sol over 20 min. The mixture was stirred at 35°C for 60 min to obtain a modified boron-aluminum-silicon transition sol. Step 7: The modified boron-aluminum-silicon transition sol obtained in Step 6 is sprayed twice onto the glazed area of ​​the porcelain blank treated in Step 4, under the same spraying conditions as in Step 4; the first spray is 30g, and after spraying, it is placed at 25℃ for 8 minutes; the second spray is 26g, and after spraying, it is placed at 25℃ for 12 minutes; a witness porcelain blank obtained from the same batch of clay and the same drying regime as the official porcelain blank is taken, and 20mg of Rhodamine B is added to 100g of the modified boron-aluminum-silicon transition sol obtained in Step 6, and the witness porcelain blank is treated under the same spraying conditions as in this step; after the witness porcelain blank is treated under the same drying regime as in Step 8, it is cut vertically, and the distance from the color front to the surface at 10 positions is measured using a 50x stereomicroscope, with an average wetting depth of 105μm; no Rhodamine B is added to the official porcelain blank.

[0025] Step 8: Dry the wetted porcelain blank obtained in Step 7 at 40℃ for 30 min, 75℃ for 90 min and 110℃ for 60 min in sequence; Step 9: Add 380g potassium feldspar powder, 300g fused silica powder, 120g kaolin concentrate, 80g calcite powder, 60g talc powder, 40g reactive alumina powder, 20g iron oxide brown material, 550g deionized water, and 3g sodium tripolyphosphate to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2. Ball mill at 250r / min for 12h, and pass through a 325-mesh sieve to obtain a ceramic porcelain raw glaze slurry. Spray 240g of the ceramic porcelain raw glaze slurry onto the glazing area of ​​the ceramic blank obtained in Step 8. The spraying pressure is 0.25MPa, the nozzle diameter is 1mm, the spray gun outlet is 20cm away from the ceramic blank surface, and the ceramic blank rotates at 20r / min. After spraying, dry at 80℃ for 120min. Step 10: Place the glazed porcelain blank obtained in Step 9 into an electric porcelain firing kiln. Under an oxidizing atmosphere, raise the temperature from 25°C to 200°C at a rate of 30°C / h and hold for 2 hours; continue raising the temperature to 600°C at a rate of 60°C / h and hold for 2 hours; continue raising the temperature to 980°C at a rate of 90°C / h and hold for 1 hour; continue raising the temperature to 1280°C at a rate of 70°C / h and hold for 3 hours; then lower the temperature to 1000°C at a rate of 60°C / h and hold for 1 hour; then lower the temperature to 600°C at a rate of 80°C / h, and then allow it to cool with the kiln to below 80°C before removing it from the kiln to obtain the fired porcelain piece. Step 11: Mix 500g of silicate cement, 150g of refined quartz sand and 180g of deionized water for 10 minutes to obtain cementitious binder; glue the fired ceramic part obtained in Step 10 to a commercially available iron cap and steel foot conforming to GB / T7253-2019 for 120kN ball socket connection. After gluing, cure for 28 days at 25℃ and 90% relative humidity to obtain a porcelain suspension insulator.

[0026] Example 2: Step 1: Add 850g reactive alumina powder, 1000g kaolin concentrate, 320g potassium feldspar powder, 220g fused silica powder, 1040g deionized water, 4g sodium tripolyphosphate, and 6g sodium carboxymethyl cellulose to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2 and ball mill at 250r / min for 18h. After ball milling, pass the slurry through a 325-mesh sieve. Degas the sieved slurry under a vacuum of -90kPa for 20min, filter until the moisture content is 18.5%, and vacuum knead the slurry three times. Then, place it into a disc-shaped suspension porcelain insulator metal mold and press it at 22MPa for 3min. After demolding, the exposed glazed area is 2300cm². 2 The wet blank of the disc-shaped suspension porcelain insulator; Step 2: Dry the wet blank of the disc suspension porcelain insulator obtained in Step 1 at 45℃ for 8 hours, and then turn it to trim the blank according to the shape of the 120kN disc suspension porcelain insulator; dry the trimmed porcelain blank at 80℃ for 6 hours, and then at 110℃ for 6 hours. Measure the moisture content of the porcelain blank by the 105℃ weight loss method. The moisture content should not be higher than 1%, and the dried porcelain blank is obtained. Step 3: Place 380g of deionized water in a glass container, and slowly add 3.5g of 65% nitric acid at 25℃ and 300r / min with stirring, and stir for 10min; then add 70g of anhydrous ethanol and stir for 10min; then add 26g of boehmite powder and stir at 25℃ and 600r / min for 60min to obtain uncomplexed highly dispersed boehmite anchoring sol; Step 4: Weigh 18g of the uncomplexed highly dispersed boehmite anchoring sol obtained in Step 3, and spray it onto the glazing area of ​​the dried ceramic blank obtained in Step 2 using a regular spray gun with a nozzle diameter of 1mm. The spraying pressure is 0.25MPa, the nozzle of the spray gun is 20cm away from the surface of the ceramic blank, and the ceramic blank is rotated at 20r / min. After spraying, place the ceramic blank at 35℃ for 15min, and then dry it at 55℃ for 25min to obtain a ceramic blank that has been anchored on the inside by uncomplexed highly dispersed boehmite powder. Step 5: Add 45g of deionized water, 8g of citric acid monohydrate and 26g of dispersible boehmite powder to a glass container and stir at 50℃ and 600r / min for 40min to obtain a citric acid complexed highly dispersed boehmite dispersion. Step 6: Add 110g of tetraethyl orthosilicate to 260g of anhydrous ethanol and stir at 25℃ and 400r / min for 20min to obtain a tetraethyl orthosilicate ethanol solution; separately, mix 110g of deionized water and 4.5g of 65% nitric acid and cool to 25℃ to obtain an acid-water solution; under stirring conditions of 35℃ and 500r / min, add the acid-water solution dropwise to the tetraethyl orthosilicate ethanol solution over 30min, controlling the liquid temperature not to exceed 40℃ during the dropwise addition. After the dropwise addition is completed, continue stirring at 35℃ for 60min to obtain a hydrolyzed silica sol; add 210g of deionized water, 185g of aluminum nitrate nonahydrate, and 18g of boric acid to... In another glass container, the mixture was stirred at 50°C and 500 rpm for 40 min to obtain a boron-aluminum aqueous solution. The boron-aluminum aqueous solution was added dropwise to the hydrolyzed silica sol over 60 min. After the addition was complete, the mixture was stirred at 35°C for 120 min. 110 g of colloidal silica was added over 20 min, and the mixture was stirred at 35°C for 60 min. The citric acid complexed highly dispersed boehmite dispersion obtained in step 5 was then added, and the mixture was stirred at 35°C for 60 min. Finally, 90 g of deionized water and 14 g of polyethylene glycol were dissolved at 60°C, cooled to 35°C, and added to the above sol over 20 min. The mixture was stirred at 35°C for 60 min to obtain a modified boron-aluminum-silicon transition sol. Step 7: The modified boron-aluminum-silicon transition sol obtained in Step 6 is sprayed twice onto the glazed area of ​​the porcelain blank treated in Step 4, under the same spraying conditions as in Step 4; the first spray is 28g, and after spraying, it is placed at 25℃ for 8 minutes; the second spray is 24g, and after spraying, it is placed at 25℃ for 10 minutes; a witness porcelain blank obtained from the same batch of clay and the same drying regime as the final porcelain blank is taken, and 20mg of Rhodamine B is added to 100g of the modified boron-aluminum-silicon transition sol obtained in Step 6, and the witness porcelain blank is treated under the same spraying conditions as in this step; after the witness porcelain blank is treated under the same drying regime as in Step 8, it is cut vertically, and the distance from the color front to the surface at 10 positions is measured using a 50x stereomicroscope, with an average wetting depth of 92μm; no Rhodamine B is added to the final porcelain blank; Step 8: Dry the wetted porcelain blank obtained in Step 7 at 38℃ for 25 min, 70℃ for 80 min and 105℃ for 50 min in sequence; Step 9: Add 360g potassium feldspar powder, 320g fused silica powder, 130g kaolin concentrate, 70g calcite powder, 50g talc powder, 35g reactive alumina powder, 15g iron oxide brown material, 520g deionized water, and 2.5g sodium tripolyphosphate to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2. Ball mill at 250r / min for 12h, and pass through a 325-mesh sieve to obtain a ceramic porcelain raw glaze slurry. Spray 230g of the ceramic porcelain raw glaze slurry onto the glazing area of ​​the ceramic blank obtained in Step 8. The spraying pressure is 0.25MPa, the nozzle diameter is 1mm, the spray gun outlet is 20cm away from the ceramic blank surface, and the ceramic blank rotates at 20r / min. After spraying, dry at 80℃ for 120min. Step 10: Place the glazed porcelain blank obtained in Step 9 into an electric porcelain firing kiln. Under an oxidizing atmosphere, raise the temperature from 25°C to 200°C at a rate of 30°C / h and hold for 2 hours; continue raising the temperature to 600°C at a rate of 60°C / h and hold for 2 hours; continue raising the temperature to 980°C at a rate of 90°C / h and hold for 1 hour; continue raising the temperature to 1260°C at a rate of 70°C / h and hold for 3.5 hours; then lower the temperature to 1000°C at a rate of 60°C / h and hold for 1 hour; then lower the temperature to 600°C at a rate of 80°C / h, and then allow it to cool in the kiln to below 80°C before removing it from the kiln to obtain the fired porcelain piece. Step 11: Mix 500g of silicate cement, 150g of refined quartz sand and 180g of deionized water for 10 minutes to obtain cementitious binder; glue the fired ceramic part obtained in Step 10 to a commercially available iron cap and steel foot conforming to GB / T7253-2019 for 120kN ball socket connection. After gluing, cure for 28 days at 25℃ and 90% relative humidity to obtain a porcelain suspension insulator.

[0027] Example 3: Step 1: Add 950g reactive alumina powder, 900g kaolin concentrate, 380g potassium feldspar powder, 280g fused silica powder, 1160g deionized water, 6g sodium tripolyphosphate, and 10g sodium carboxymethyl cellulose to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2 and ball mill at 250r / min for 18h. After ball milling, pass the slurry through a 325-mesh sieve. Degas the sieved slurry under a vacuum of -90kPa for 20min, filter until the moisture content is 18.5%, and vacuum knead the slurry three times. Then, place it into a disc-shaped suspension porcelain insulator metal mold and press it at 28MPa for 3min. After demolding, the exposed glazed area is 2300cm². 2 The wet blank of the disc-shaped suspension porcelain insulator; Step 2: Dry the wet blank of the disc suspension porcelain insulator obtained in Step 1 at 45℃ for 8 hours, and then turn it to trim the blank according to the shape of the 120kN disc suspension porcelain insulator; dry the trimmed porcelain blank at 80℃ for 6 hours, and then at 110℃ for 6 hours. Measure the moisture content of the porcelain blank by the 105℃ weight loss method. The moisture content should not be higher than 1%, and the dried porcelain blank is obtained. Step 3: Place 420g of deionized water in a glass container, and slowly add 4.5g of 65% nitric acid at 25℃ and 300r / min with stirring, and stir for 10min; then add 90g of anhydrous ethanol and stir for 10min; then add 34g of boehmite powder and stir at 25℃ and 600r / min for 60min to obtain uncomplexed highly dispersed boehmite anchoring sol; Step 4: Weigh 22g of the uncomplexed highly dispersed boehmite anchoring sol obtained in Step 3, and spray it onto the glazing area of ​​the dried ceramic blank obtained in Step 2 using a regular spray gun with a nozzle diameter of 1mm. The spraying pressure is 0.25MPa, the nozzle of the spray gun is 20cm away from the surface of the ceramic blank, and the ceramic blank is rotated at 20r / min. After spraying, place the ceramic blank at 35℃ for 25min, and then dry it at 65℃ for 35min to obtain a ceramic blank that has been anchored on the inside by uncomplexed highly dispersed boehmite powder. Step 5: Add 55g of deionized water, 12g of citric acid monohydrate and 34g of dispersible boehmite powder to a glass container and stir at 50℃ and 600r / min for 40min to obtain a citric acid complexed highly dispersed boehmite dispersion. Step 6: Add 130g of tetraethyl orthosilicate to 300g of anhydrous ethanol and stir at 25℃ and 400r / min for 20min to obtain a tetraethyl orthosilicate ethanol solution; separately, mix 130g of deionized water and 5.5g of 65% nitric acid and cool to 25℃ to obtain an acid-water solution; under stirring conditions of 35℃ and 500r / min, add the acid-water solution dropwise to the tetraethyl orthosilicate ethanol solution over 30min, controlling the liquid temperature not to exceed 40℃ during the dropwise addition. After the dropwise addition is completed, continue stirring at 35℃ for 60min to obtain a hydrolyzed silica sol; add 230g of deionized water, 215g of aluminum nitrate nonahydrate, and 26g of boric acid to... In another glass container, the mixture was stirred at 50°C and 500 rpm for 40 min to obtain a boron-aluminum aqueous solution. The boron-aluminum aqueous solution was added dropwise to the hydrolyzed silica sol over 60 min. After the addition was complete, the mixture was stirred at 35°C for 120 min. 130 g of colloidal silica was added over 20 min, and the mixture was stirred at 35°C for 60 min. The citric acid complexed highly dispersed boehmite dispersion obtained in step 5 was then added, and the mixture was stirred at 35°C for 60 min. Finally, 110 g of deionized water and 22 g of polyethylene glycol were dissolved at 60°C, cooled to 35°C, and added to the above sol over 20 min. The mixture was stirred at 35°C for 60 min to obtain a modified boron-aluminum-silicon transition sol. Step 7: The modified boron-aluminum-silicon transition sol obtained in Step 6 is sprayed twice onto the glazed area of ​​the porcelain blank treated in Step 4, under the same spraying conditions as in Step 4; the first spray is 32g, and after spraying, it is placed at 25℃ for 10min; the second spray is 28g, and after spraying, it is placed at 25℃ for 14min; a witness porcelain blank obtained from the same batch of clay and the same drying regime as the final porcelain blank is taken, and 20mg of Rhodamine B is added to 100g of the modified boron-aluminum-silicon transition sol obtained in Step 6, and the witness porcelain blank is treated under the same spraying conditions as in this step; after the witness porcelain blank is treated under the same drying regime as in Step 8, it is cut vertically, and the distance from the color front to the surface at 10 positions is measured using a 50x stereomicroscope, with an average wetting depth of 118μm; no Rhodamine B is added to the final porcelain blank; Step 8: Dry the wetted porcelain blank obtained in Step 7 at 42℃ for 35 min, 80℃ for 100 min, and 115℃ for 70 min in sequence; Step 9: Add 400g potassium feldspar powder, 280g fused silica powder, 110g kaolin concentrate, 90g calcite powder, 70g talc powder, 45g reactive alumina powder, 25g iron oxide brown material, 580g deionized water, and 3.5g sodium tripolyphosphate to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2. Ball mill at 250r / min for 12h, and pass through a 325-mesh sieve to obtain a ceramic porcelain raw glaze slurry. Spray 250g of the ceramic porcelain raw glaze slurry onto the glazing area of ​​the ceramic blank obtained in Step 8. The spraying pressure is 0.25MPa, the nozzle diameter is 1mm, the spray gun outlet is 20cm away from the ceramic blank surface, and the ceramic blank rotates at 20r / min. After spraying, dry at 80℃ for 120min. Step 10: Place the glazed porcelain blank obtained in Step 9 into an electric porcelain firing kiln. Under an oxidizing atmosphere, raise the temperature from 25°C to 200°C at a rate of 30°C / h and hold for 2 hours; continue raising the temperature to 600°C at a rate of 60°C / h and hold for 2 hours; continue raising the temperature to 980°C at a rate of 90°C / h and hold for 1 hour; continue raising the temperature to 1300°C at a rate of 70°C / h and hold for 2.5 hours; then lower the temperature to 1000°C at a rate of 60°C / h and hold for 1 hour; then lower the temperature to 600°C at a rate of 80°C / h, and then allow it to cool with the kiln to below 80°C before removing it from the kiln to obtain the fired porcelain piece. Step 11: Mix 500g of silicate cement, 150g of refined quartz sand and 180g of deionized water for 10 minutes to obtain cementitious binder; glue the fired ceramic part obtained in Step 10 to a commercially available iron cap and steel foot conforming to GB / T7253-2019 for 120kN ball socket connection. After gluing, cure for 28 days at 25℃ and 90% relative humidity to obtain a porcelain suspension insulator.

[0028] Example 4: Step 1: Add 880g reactive alumina powder, 970g kaolin concentrate, 340g potassium feldspar powder, 240g fused silica powder, 1080g deionized water, 5g sodium tripolyphosphate, and 7g sodium carboxymethyl cellulose to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2 and ball mill at 250r / min for 18h. After ball milling, pass the slurry through a 325-mesh sieve. Degas the sieved slurry under a vacuum of -90kPa for 20min, filter until the moisture content is 18.5%, and vacuum knead the slurry three times. Then, place it into a disc-shaped suspension porcelain insulator metal mold and press it at 24MPa for 3min. After demolding, the exposed glazed area is 2300cm². 2 The wet blank of the disc-shaped suspension porcelain insulator; Step 2: Dry the wet blank of the disc suspension porcelain insulator obtained in Step 1 at 45℃ for 8 hours, and then turn it to trim the blank according to the shape of the 120kN disc suspension porcelain insulator; dry the trimmed porcelain blank at 80℃ for 6 hours, and then at 110℃ for 6 hours. Measure the moisture content of the porcelain blank by the 105℃ weight loss method. The moisture content should not be higher than 1%, and the dried porcelain blank is obtained. Step 3: Place 400g of deionized water in a glass container, and slowly add 4g of 65% nitric acid at 25℃ and 300r / min with stirring, and stir for 10min; then add 75g of anhydrous ethanol and stir for 10min; then add 28g of boehmite powder and stir at 25℃ and 600r / min for 60min to obtain uncomplexed highly dispersed boehmite anchoring sol; Step 4: Weigh 19g of the uncomplexed highly dispersed boehmite anchoring sol obtained in Step 3, and spray it onto the glazing area of ​​the dried ceramic blank obtained in Step 2 using a regular spray gun with a nozzle diameter of 1mm. The spraying pressure is 0.25MPa, the nozzle of the spray gun is 20cm away from the surface of the ceramic blank, and the ceramic blank is rotated at 20r / min. After spraying, place the ceramic blank at 35℃ for 18min, and then dry it at 60℃ for 28min to obtain a ceramic blank that has been anchored on the inside by uncomplexed highly dispersed boehmite powder. Step 5: Add 48g of deionized water, 9g of citric acid monohydrate and 28g of dispersible boehmite powder to a glass container and stir at 50℃ and 600r / min for 40min to obtain a citric acid complexed highly dispersed boehmite dispersion. Step 6: Add 115g of tetraethyl orthosilicate to 270g of anhydrous ethanol and stir at 25℃ and 400r / min for 20min to obtain a tetraethyl orthosilicate ethanol solution; separately, mix 115g of deionized water and 5g of 65% nitric acid and cool to 25℃ to obtain an acid-water solution; under stirring conditions of 35℃ and 500r / min, add the acid-water solution dropwise to the tetraethyl orthosilicate ethanol solution over 30min, controlling the liquid temperature not to exceed 40℃ during the addition. After the addition is complete, continue stirring at 35℃ for 60min to obtain a hydrolyzed silica sol; add 215g of deionized water, 190g of aluminum nitrate nonahydrate, and 20g of boric acid to another... In a glass container, a boron-aluminum aqueous solution was obtained by stirring at 50°C and 500 rpm for 40 min. The boron-aluminum aqueous solution was then added dropwise to a hydrolyzed silica sol over 60 min. After the addition was complete, the mixture was stirred at 35°C for 120 min. 115 g of colloidal silica was added over 20 min, and the mixture was stirred at 35°C for 60 min. Subsequently, the citric acid-complexed highly dispersed boehmite dispersion obtained in step 5 was added, and the mixture was stirred at 35°C for 60 min. Finally, 95 g of deionized water and 16 g of polyethylene glycol were dissolved at 60°C, cooled to 35°C, and added to the above sol over 20 min. The mixture was stirred at 35°C for 60 min to obtain a modified boron-aluminum-silicon transition sol. Step 7: The modified boron-aluminum-silicon transition sol obtained in Step 6 is sprayed twice onto the glazed area of ​​the porcelain blank treated in Step 4, under the same spraying conditions as in Step 4; the first spray is 29g, and after spraying, it is placed at 25℃ for 8 minutes; the second spray is 25g, and after spraying, it is placed at 25℃ for 11 minutes; a witness porcelain blank obtained from the same batch of clay and the same drying regime as the final porcelain blank is taken, and 20mg of Rhodamine B is added to 100g of the modified boron-aluminum-silicon transition sol obtained in Step 6, and the witness porcelain blank is treated under the same spraying conditions as in this step; after the witness porcelain blank is treated under the same drying regime as in Step 8, it is cut vertically, and the distance from the color front to the surface at 10 positions is measured using a 50x stereomicroscope, with an average wetting depth of 99μm; no Rhodamine B is added to the final porcelain blank; Step 8: Dry the wetted porcelain blank obtained in Step 7 at 40℃ for 30 min, 75℃ for 85 min, and 110℃ for 60 min in sequence; Step 9: Add 370g potassium feldspar powder, 310g fused silica powder, 125g kaolin concentrate, 75g calcite powder, 55g talc powder, 38g reactive alumina powder, 18g iron oxide brown material, 540g deionized water, and 3g sodium tripolyphosphate to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2. Ball mill at 250r / min for 12h, and pass through a 325-mesh sieve to obtain a ceramic porcelain raw glaze slurry. Spray 235g of the ceramic porcelain raw glaze slurry onto the glazing area of ​​the ceramic blank obtained in Step 8. The spraying pressure is 0.25MPa, the nozzle diameter is 1mm, the spray gun outlet is 20cm away from the ceramic blank surface, and the ceramic blank rotates at 20r / min. After spraying, dry at 80℃ for 120min. Step 10: Place the glazed porcelain blank obtained in Step 9 into an electric porcelain firing kiln. Under an oxidizing atmosphere, raise the temperature from 25°C to 200°C at a rate of 30°C / h and hold for 2 hours; continue raising the temperature to 600°C at a rate of 60°C / h and hold for 2 hours; continue raising the temperature to 980°C at a rate of 90°C / h and hold for 1 hour; continue raising the temperature to 1270°C at a rate of 70°C / h and hold for 3.2 hours; then lower the temperature to 1000°C at a rate of 60°C / h and hold for 1 hour; then lower the temperature to 600°C at a rate of 80°C / h, and then allow it to cool in the kiln to below 80°C before removing it from the kiln to obtain the fired porcelain piece. Step 11: Mix 500g of silicate cement, 150g of refined quartz sand and 180g of deionized water for 10 minutes to obtain cementitious binder; glue the fired ceramic part obtained in Step 10 to a commercially available iron cap and steel foot conforming to GB / T7253-2019 for 120kN ball socket connection. After gluing, cure for 28 days at 25℃ and 90% relative humidity to obtain a porcelain suspension insulator.

[0029] Example 5: Step 1: Add 930g reactive alumina powder, 930g kaolin concentrate, 370g potassium feldspar powder, 270g fused silica powder, 1140g deionized water, 5.5g sodium tripolyphosphate, and 9g sodium carboxymethyl cellulose to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2 and ball mill at 250r / min for 18h. After ball milling, pass the slurry through a 325-mesh sieve. Degas the sieved slurry under a vacuum of -90kPa for 20min, filter until the moisture content is 18.5%, and vacuum knead the slurry three times. Then, place it into a disc-shaped suspension porcelain insulator metal mold and press it at 27MPa for 3min. After demolding, the exposed glazed area is 2300cm². 2 The wet blank of the disc-shaped suspension porcelain insulator; Step 2: Dry the wet blank of the disc suspension porcelain insulator obtained in Step 1 at 45℃ for 8 hours, and then turn it to trim the blank according to the shape of the 120kN disc suspension porcelain insulator; dry the trimmed porcelain blank at 80℃ for 6 hours, and then at 110℃ for 6 hours. Measure the moisture content of the porcelain blank by the 105℃ weight loss method. The moisture content should not be higher than 1%, and the dried porcelain blank is obtained. Step 3: Place 410g of deionized water in a glass container, and slowly add 4.2g of 65% nitric acid at 25℃ and 300r / min with stirring, and stir for 10min; then add 85g of anhydrous ethanol and stir for 10min; then add 32g of boehmite powder and stir at 25℃ and 600r / min for 60min to obtain uncomplexed highly dispersed boehmite anchoring sol; Step 4: Weigh 21g of the uncomplexed highly dispersed boehmite anchoring sol obtained in Step 3, and spray it onto the glazing area of ​​the dried ceramic blank obtained in Step 2 using a regular spray gun with a nozzle diameter of 1mm. The spraying pressure is 0.25MPa, the nozzle of the spray gun is 20cm away from the surface of the ceramic blank, and the ceramic blank is rotated at 20r / min. After spraying, place the ceramic blank at 35℃ for 22min, and then dry it at 62℃ for 32min to obtain a ceramic blank that has been anchored on the inside by uncomplexed highly dispersed boehmite powder. Step 5: Add 53g of deionized water, 11g of citric acid monohydrate and 32g of dispersible boehmite powder to a glass container and stir at 50℃ and 600r / min for 40min to obtain a citric acid complexed highly dispersed boehmite dispersion. Step 6: Add 125g of tetraethyl orthosilicate to 290g of anhydrous ethanol and stir at 25℃ and 400r / min for 20min to obtain a tetraethyl orthosilicate ethanol solution; separately, mix 125g of deionized water and 5.2g of 65% nitric acid and cool to 25℃ to obtain an acid-water solution; under stirring conditions of 35℃ and 500r / min, add the acid-water solution dropwise to the tetraethyl orthosilicate ethanol solution over 30min, controlling the liquid temperature not to exceed 40℃ during the dropwise addition. After the dropwise addition is completed, continue stirring at 35℃ for 60min to obtain a hydrolyzed silica sol; add 225g of deionized water, 210g of aluminum nitrate nonahydrate, and 24g of boric acid to... In another glass container, the mixture was stirred at 50°C and 500 rpm for 40 min to obtain a boron-aluminum aqueous solution. The boron-aluminum aqueous solution was added dropwise to the hydrolyzed silica sol over 60 min. After the addition was complete, the mixture was stirred at 35°C for 120 min. 125 g of colloidal silica was added over 20 min, and the mixture was stirred at 35°C for 60 min. The citric acid complexed highly dispersed boehmite dispersion obtained in step 5 was then added, and the mixture was stirred at 35°C for 60 min. Finally, 105 g of deionized water and 20 g of polyethylene glycol were dissolved at 60°C, cooled to 35°C, and added to the above sol over 20 min. The mixture was stirred at 35°C for 60 min to obtain a modified boron-aluminum-silicon transition sol. Step 7: The modified boron-aluminum-silicon transition sol obtained in Step 6 is sprayed twice onto the glazed area of ​​the porcelain blank treated in Step 4, under the same spraying conditions as in Step 4; the first spray is 31g, and after spraying, it is placed at 25℃ for 9 minutes; the second spray is 27g, and after spraying, it is placed at 25℃ for 13 minutes; a witness porcelain blank obtained from the same batch of clay and the same drying regime as the final porcelain blank is taken, and 20mg of Rhodamine B is added to 100g of the modified boron-aluminum-silicon transition sol obtained in Step 6, and the witness porcelain blank is treated under the same spraying conditions as in this step; after the witness porcelain blank is treated under the same drying regime as in Step 8, it is cut vertically, and the distance from the color front to the surface at 10 positions is measured using a 50x stereomicroscope, with an average wetting depth of 112μm; no Rhodamine B is added to the final porcelain blank; Step 8: Dry the wetted porcelain blank obtained in Step 7 at 41℃ for 33 min, 78℃ for 95 min, and 112℃ for 65 min in sequence; Step 9: Add 390g potassium feldspar powder, 290g fused silica powder, 115g kaolin concentrate, 85g calcite powder, 65g talc powder, 42g reactive alumina powder, 22g iron oxide brown material, 565g deionized water, and 3.2g sodium tripolyphosphate to an alumina ball mill jar. Add alumina balls at a material-to-ball mass ratio of 1:2. Ball mill at 250r / min for 12h, and pass through a 325-mesh sieve to obtain a ceramic porcelain raw glaze slurry. Spray 245g of the ceramic porcelain raw glaze slurry onto the glazing area of ​​the ceramic blank obtained in Step 8. The spraying pressure is 0.25MPa, the nozzle diameter is 1mm, the spray gun outlet is 20cm away from the ceramic blank surface, and the ceramic blank rotates at 20r / min. After spraying, dry at 80℃ for 120min. Step 10: Place the glazed porcelain blank obtained in Step 9 into an electric porcelain firing kiln. Under an oxidizing atmosphere, raise the temperature from 25°C to 200°C at a rate of 30°C / h and hold for 2 hours; continue raising the temperature to 600°C at a rate of 60°C / h and hold for 2 hours; continue raising the temperature to 980°C at a rate of 90°C / h and hold for 1 hour; continue raising the temperature to 1290°C at a rate of 70°C / h and hold for 2.8 hours; then lower the temperature to 1000°C at a rate of 60°C / h and hold for 1 hour; then lower the temperature to 600°C at a rate of 80°C / h, and then allow it to cool with the kiln to below 80°C before removing it from the kiln to obtain the fired porcelain piece. Step 11: Mix 500g of silicate cement, 150g of refined quartz sand and 180g of deionized water for 10 minutes to obtain cementitious binder; glue the fired ceramic part obtained in Step 10 to a commercially available iron cap and steel foot conforming to GB / T7253-2019 for 120kN ball socket connection. After gluing, cure for 28 days at 25℃ and 90% relative humidity to obtain a porcelain suspension insulator.

[0030] Comparative Example 1: The difference from Example 1 is that in step 7, after the first spraying, the ceramic blank was placed at 25°C for 2 minutes and after the second spraying for 3 minutes. The average penetration depth of the ceramic blank was measured to be 72 μm using the same method. The other conditions were the same as in Example 1.

[0031] Comparative Example 2: The difference from Example 1 is that in step 7, after the first spraying, the ceramic blank was placed at 25°C for 25 minutes and after the second spraying for 35 minutes. The average penetration depth of the ceramic blank was measured to be 145 μm using the same method. The other conditions were the same as in Example 1.

[0032] Comparative Example 3: The difference from Example 1 is that in step 3, 30g of boehmite powder is replaced with 30g of reactive alumina powder, and the spraying amount, spraying conditions and drying conditions in step 4 remain unchanged. The other conditions are the same as in Example 1.

[0033] Comparative Example 4: The difference from Example 1 is that in step 5, instead of adding 10g of citric acid monohydrate, 10g of deionized water is added, so that the total mass of the dispersion obtained in step 5 is still 90g. The other conditions are the same as in Example 1.

[0034] Comparative Example 5: The difference from Example 1 is that 18g of polyethylene glycol is not added in step 6. Instead, the amount of deionized water added at the end is adjusted from 100g to 118g, so that the total mass of the sol obtained in step 6 is the same as that in Example 1. All other conditions are the same as those in Example 1.

[0035] Comparative Example 6: The difference from Example 1 is that the number average molecular weight of polyethylene glycol in step 6 is adjusted from 20,000 to 4,000, the amount of polyethylene glycol used is still 18g, and the other conditions are the same as in Example 1.

[0036] Comparative Example 7: The difference from Example 1 is that in step 8, instead of the segmented drying process of drying at 40°C for 30 min, 75°C for 90 min, and 110°C for 60 min, the drying is carried out directly at 110°C for 180 min, and the other conditions are the same as in Example 1.

[0037] Comparative Example 8: The difference from Example 1 is that: the modified boron-aluminum-silicon transition sol obtained in step 6 is first sprayed onto the glazed area of ​​the dried ceramic blank obtained in step 2 according to the two spraying amounts and placement time in step 7, and then dried according to step 8. Then, the uncomplexed highly dispersed boehmite anchoring sol obtained in step 3 is sprayed according to the spraying amount, spraying conditions and drying conditions in step 4. The other conditions are the same as in Example 1.

[0038] Performance testing: Test Sample Preparation: Performance test samples were derived from Examples 1-5 and Comparative Examples 1-8. For each example or comparative example, 12 120kN disc-shaped suspension porcelain insulators were prepared. Six were used for visual crack observation and electromechanical failure load testing after thermal cycling, three were used for artificial pollution power frequency flashover voltage and leakage current testing, and three were reserved as verification samples. In each example and comparative example, while preparing the wet blank in step 1, strip blanks with dimensions of 45mm×4mm×3mm, thermally expanded blanks with dimensions of 25mm×5mm×5mm, and witness porcelain blanks with dimensions of 40mm×40mm×10mm were simultaneously prepared using the same batch of clay. One side surface of the strip blanks and thermally expanded blanks underwent the same anchoring, wetting, drying, and glazing treatment as steps 3 to 9 of the corresponding example or comparative example, and were fired in the same kiln as the corresponding porcelain pieces. After curing the glued samples at 25℃ and 90% relative humidity for 28 days, the application performance was tested. After firing the strip-shaped samples and the thermally expanded samples in the same kiln, they were placed at 25℃ and 50% relative humidity for 48 hours before the intrinsic performance was tested.

[0039] Average wetting depth and transition interface continuity: Witness porcelain blanks obtained from the same batch of clay and drying regime as the final porcelain blanks in each example and comparative example were used. 20 mg of Rhodamine B was added to 100 g of the corresponding modified boron-aluminum-silica transition sol. The blanks were treated according to the spraying amount, spraying pressure, nozzle diameter, spray gun distance, porcelain blank rotation speed, and placement time as per step 7, and then dried according to step 8. The dried witness porcelain blanks were cut along a direction perpendicular to the glazed surface, and the distance from the color front to the surface at 10 locations was measured under a 50x stereomicroscope. The arithmetic mean was taken as the average wetting depth. The continuity rate of the transition interface was observed under a microscope according to GB / T5594.8-2015, and the energy spectrum of aluminum and silicon elements was scanned according to GB / T17359-2023. Cross-sectional samples were cut from the glazed area at the root of the umbrella skirt of the fired ceramic piece, and were polished with 400-grit, 800-grit, 1200-grit and 2000-grit metallographic sandpaper in sequence, then polished with 1μm diamond polishing paste, sputter-coated with gold, and observed under a scanning electron microscope with an accelerating voltage of 15kV. Twenty fields of view were taken for each sample, with a field width of 500μm. The fields of view in which the aluminum and silicon elements in the direction from the glaze layer to the body are continuously and gradually changed without the appearance of through cracks with a length greater than 10μm were counted as continuous fields of view. The continuity rate of the transition interface was calculated as the percentage of the number of continuous fields of view to the 20 fields of view.

[0040] Linear expansion difference: The linear expansion difference was determined using the push rod method according to GB / T16535-2008. For each example and comparative example, surface composite specimens and inner green body specimens were prepared. The surface composite specimens were 25mm × 5mm × 5mm in size, retaining the surface layer obtained after anchoring, wetting, glazing, and firing. The inner green body specimens were cut from the interior of the green body at least 2mm above the glazed surface of the same fired ceramic piece, with dimensions of 25mm × 5mm × 5mm. Before testing, the specimens were dried at 110℃ for 2 hours and cooled to 25℃. The testing temperature range was 25℃ to 300℃, with a heating rate of 5℃ / min. The average linear expansion coefficients of the surface composite specimens and inner green body specimens were recorded, and the absolute value of the difference between the two was recorded as the linear expansion difference. Five specimens were tested in each group, and the arithmetic mean was taken.

[0041] Room temperature flexural strength: Room temperature flexural strength was determined using the three-point bending method according to GB / T6569-2006. Strip samples were used with the same batch of clay, surface treatment, glazing, and firing in the same kiln as those used in the examples and comparative examples. After firing, the strip samples were machined to 45mm × 4mm × 3mm, with the four long sides chamfered and polished, retaining one glazed and transition-treated tensile surface. During testing, the support span was 30mm, the loading head was located at the midpoint of the span, and the loading rate was 0.5mm / min. The glazed surface was placed downwards as the tensile surface. The fracture load was recorded, and the room temperature flexural strength was calculated. Ten strip samples were tested in each group. Invalid samples due to missing edges were discarded, and the arithmetic mean was taken.

[0042] Room temperature fracture toughness: Room temperature fracture toughness was determined using the single-sided V-beam method according to GB / T44547-2024. Strip samples with the same batch of clay, surface treatment, glazing, and firing in the same kiln as those used in the examples and comparative examples were used. The processed dimensions were 45mm × 4mm × 3mm. A V-shaped notch was prepared on one side of the glazed surface, with a notch depth of 1.2mm and a root radius not exceeding 20μm. The test employed a three-point bending load with a support span of 30mm and a loading rate of 0.05mm / min. The fracture load, notch depth, and sample size were recorded, and the fracture toughness was calculated using the single-sided V-beam method. Eight samples were tested in each group, and the arithmetic mean was taken.

[0043] Number of circumferential cracks after thermal cycling: The number of circumferential cracks after thermal cycling was determined according to the temperature cycling test method for porcelain or glass insulators in GB / T1001.1-2021. Intact porcelain suspension insulators cured for 28 days were placed in a 75℃ constant temperature water bath for 30 minutes, then transferred to a 15℃ constant temperature water bath within 30 seconds for another 30 minutes, completing one thermal cycle. Each sample underwent 20 consecutive thermal cycles. After cycling, the samples were left to stand at 25℃ for 2 hours, surface moisture was wiped off, and the samples were observed circumferentially along the base of the skirt, the outer circle of the head, and the tensile section under 500 lx illumination. Red penetrating liquid was used to aid in the visualization of cracks. Cracks longer than 3 mm and extending circumferentially were counted as circumferential cracks. Six intact porcelain suspension insulators were tested in each group, and the results were expressed as the arithmetic mean of the number of circumferential cracks for each sample.

[0044] Electromechanical failure load after thermal cycling: The electromechanical failure load after thermal cycling is determined according to GB / T1001.1-2021 and GB / T7253-2019. After completing test item six (thermal cycling) and visual inspection, intact porcelain suspension insulators are installed in the ball-and-socket clamp of a 500kN electro-hydraulic servo tensile testing machine, ensuring the axes of the iron cap and steel foot coincide with the loading axis. The iron cap is grounded, and the steel foot is connected to the 50Hz power frequency high-voltage terminal. A 40kV power frequency voltage is applied during the test. Mechanical loading is initially applied at 5kN / s to 80kN, then continued at 2kN / s until the specimen experiences porcelain failure, adhesive failure, or electrical breakdown. The maximum load at failure is recorded as the electromechanical failure load after thermal cycling. Six intact porcelain suspension insulators are tested in each group, and the arithmetic mean is taken.

[0045] Peak values ​​of artificially polluted power frequency flashover voltage and leakage current: These values ​​are based on GB / T4585-2024. After 28 days of curing with adhesive, intact porcelain suspension insulators are cleaned with deionized water and dried at 50℃ for 4 hours. After cooling to 25℃, a pollution suspension prepared from sodium chloride, diatomaceous earth, and deionized water is uniformly coated onto the surface, achieving an equivalent salt density of 0.10 mg / cm³. 2 The density of the insoluble matter was 0.50 mg / cm². After coating, the sample was dried at 25°C and 50% relative humidity for 16 hours. The sample was placed in a fog chamber and wetted with deionized water mist for 30 minutes. Then, a 50 Hz power frequency voltage was applied, starting from 20 kV and increasing at 1 kV / min until flashover. The flashover voltage was recorded. Simultaneously, a current sensor was used to record the peak leakage current during the voltage increase process. Three complete ceramic suspension insulators were tested in each group, and each test was repeated three times. The arithmetic mean of the flashover voltage and the peak leakage current was taken.

[0046] Table 1 Performance Test Results Sample Average penetration depth / μm Transition Interface Continuity Rate / % <![CDATA[Linear expansion difference / 10 -6 K -1 > Room temperature flexural strength / MPa <![CDATA[Room temperature fracture toughness / MPa·m 1 / 2 > <![CDATA[Number of circumferential cracks per piece after thermal cycling / piece -1 > Electromechanical failure load after thermal cycling / kN Artificial contamination power frequency flashover voltage / kV Peak leakage current of artificial contaminants / mA Example 1 105 95 0.24 174.6 2.65 0.3 166.8 52.71 15.62 Example 2 92 90 0.36 160.8 2.43 0.7 155.4 49.64 18.90 Example 3 118 100 0.16 187.3 2.91 0 178.6 55.36 12.84 Example 4 99 90 0.31 165.2 2.52 0.5 160.3 50.88 17.45 Example 5 112 95 0.20 179.1 2.78 0.2 171.9 53.94 14.37 Comparative Example 1 72 60 0.87 139.4 2.01 3.2 136.2 46.92 27.82 Comparative Example 2 145 70 0.72 144.6 2.08 2.8 140.6 48.62 25.87 Comparative Example 3 104 65 0.82 140.8 2.02 3.3 134.9 47.35 27.14 Comparative Example 4 103 70 0.78 143.7 2.06 3 138.5 48.06 26.33 Comparative Example 5 132 75 0.61 150.9 2.19 2.3 146.7 50.28 22.96 Comparative Example 6 124 80 0.52 154.8 2.26 1.8 150.2 50.92 21.54 Comparative Example 7 101 55 1.04 135.5 1.94 4.2 130.8 44.86 30.46 Comparative Example 8 106 70 0.68 147.2 2.14 2.7 142.3 49.14 24.68 As shown in Table 1, the average wetting depth of Examples 1-5 is within the range of 90-120 μm, the continuity of the transition interface is 90.0%-100.0%, and the difference in linear expansion is 0.16×10⁻⁶. -6 K -1 -0.36×10 -6 K -1 This indicates that under the combined action of uncomplexed highly dispersed boehmite anchoring sol, citric acid-complexed highly dispersed boehmite dispersion, modified boron-aluminum-silica transition sol composed of tetraethyl orthosilicate hydrolyzed silica sol, aluminum nitrate nonahydrate, boric acid and colloidal silica, and polyethylene glycol with a number average molecular weight of 20,000, a relatively stable shallow transition region can be formed on the surface of the ceramic blank.

[0047] Compared to Example 1, Comparative Example 1 had an average wetting depth of only 72 μm due to the short post-spraying placement time, a decrease in the transition interface continuity rate to 60.0%, and an increase in the number of circumferential cracks to 3.2 after thermal cycling. -1 This indicates that insufficient wetting makes it difficult to effectively buffer the difference in thermal expansion and firing shrinkage between the glaze layer and the body. Although Comparative Example 2 increased the average wetting depth to 145 μm, its flexural strength, fracture toughness, and electromechanical failure load after thermal cycling were only 144.6 MPa, 2.08 MPa·m, and 144.6 MPa, respectively. 1 / 2 The values ​​of 140.6 kN indicate that simply increasing the penetration depth cannot achieve the best toughening effect.

[0048] Comparative Example 3 replaced the uncomplexed highly dispersed boehmite powder with reactive alumina powder; Comparative Example 4 did not add citric acid monohydrate; Comparative Example 5 did not add polyethylene glycol; Comparative Example 6 reduced the number-average molecular weight of polyethylene glycol to 4000; and Comparative Example 8 changed the order of the uncomplexed anchoring sol and the modified boron-aluminum-silicon transition sol. All of these results led to varying degrees of decrease in the continuity of the transition interface, the difference in linear expansion, the flexural strength, the fracture toughness, and the electrical properties of artificial dirt. This indicates that there is a synergistic relationship between the inner anchoring of highly dispersed boehmite, the complexation and dispersion of citric acid, the gated wetting of polyethylene glycol 20000, and the process sequence of anchoring before transition, rather than any single measure can replace it.

[0049] Comparative Example 7 was dried directly at 110℃ for 180 min. Although the average wetting depth was 101 μm, the continuity of the transition interface was only 55.0%, and the linear expansion difference increased to 1.04 × 10⁻⁶. -6 K -1 After thermal cycling, the number of circumferential cracks reached 4.2. -1 This indicates that the drying regime has a significant impact on the retention and uniform distribution of the sol in the shallow layer.

[0050] Example 3 employed a higher aluminum source, a higher sol-gel coating amount, a higher polyethylene glycol 20000 dosage, and a peak firing temperature of 1300℃. The average wetting depth was 118μm, the transition interface continuity reached 100.0%, and the linear expansion difference was reduced to 0.16×10⁻⁶. -6 K -1 The room temperature flexural strength and room temperature fracture toughness reached 187.3 MPa and 2.91 MPa·m, respectively. 1 / 2 No circumferential cracks were observed after thermal cycling. The electromechanical failure load reached 178.6 kN, the artificial pollution power frequency flashover voltage increased to 55.36 kV, and the peak value of the artificial pollution leakage current decreased to 12.84 mA.

[0051] In summary, this invention, through a combination of internal anchoring of uncomplexed highly dispersed boehmite powder, citric acid-complexed boehmite entering the boron-aluminum-silicon transition sol, polyethylene glycol 20000-gated shallow wetting, and segmented drying, creates a relatively continuous transition structure between the glaze layer, the shallow ceramic blank, and the internal blank. This reduces abrupt changes in thermal expansion and interfacial stress concentration, thereby improving the fracture resistance, high toughness, and electrical stability of porcelain suspension insulators under artificial pollution conditions.

[0052] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A fracture-resistant, high-toughness porcelain suspension insulator, comprising a porcelain component, an iron cap, and a steel foot, wherein the iron cap and the steel foot are respectively glued to both ends of the porcelain component using cement adhesive, characterized in that... The ceramic component includes a fired ceramic body, a glaze layer disposed on the surface of the glazed area of ​​the fired ceramic body, and a boron-aluminum-silicon transition layer located between the fired ceramic body and the glaze layer. The ceramic blank, by mass fraction, is obtained by shaping and firing a ceramic blank raw material comprising 850-950 parts reactive alumina powder, 900-1000 parts kaolin concentrate, 320-380 parts potassium feldspar powder, 220-280 parts fused silica powder, 1040-1160 parts deionized water, 4-6 parts sodium tripolyphosphate and 6-10 parts sodium carboxymethyl cellulose. The glaze layer is obtained by firing the glaze slurry of electric porcelain; the boron aluminum silicon transition layer is obtained by wetting the glazed area of ​​the porcelain blank after treatment with uncomplexed highly dispersed boehmite anchoring sol, followed by segmented drying, glazing and firing with modified boron aluminum silicon transition sol, and the average wetting depth of the boron aluminum silicon transition layer in the unfired surface of the porcelain blank is 90-120μm. The uncomplexed highly dispersed boehmite anchoring sol was prepared from 380-420 parts of deionized water, 3.5-4.5 parts of nitric acid with a mass fraction of 65%, 70-90 parts of anhydrous ethanol and 26-34 parts of boehmite powder, by mass. The modified boron-aluminum-silicon transition sol, by mass parts, is prepared from 110-130 parts tetraethyl orthosilicate, 260-300 parts anhydrous ethanol, 110-130 parts deionized water, 4.5-5.5 parts nitric acid with a mass fraction of 65%, 210-230 parts deionized water, 185-215 parts aluminum nitrate nonahydrate, 18-26 parts boric acid, 110-130 parts colloidal silica, a citric acid complexed highly dispersed boehmite dispersion prepared from 45-55 parts deionized water, 8-12 parts citric acid monohydrate, and 26-34 parts dispersible boehmite powder, 90-110 parts deionized water, and 14-22 parts polyethylene glycol with a number average molecular weight of 20,000.

2. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The reactive alumina powder has a median diameter of 300-500 nm and a specific surface area of ​​5-10 m². 2 / g; the kaolin concentrate is 325 mesh kaolin concentrate; the potassium feldspar powder is sieved through a 325 mesh sieve before use; the fused silica powder is 325 mesh fused silica powder.

3. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The colloidal silica is an aqueous suspension with a mass fraction of 30%; the alumina content of the boehmite powder and the dispersible boehmite powder is 72%, and the water-dispersible particle size is 20-30 nm.

4. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The ceramic glaze slurry, by weight, is prepared from 360-400 parts potassium feldspar powder, 280-320 parts fused silica powder, 110-130 parts kaolin concentrate, 70-90 parts calcite powder, 50-70 parts talc powder, 35-45 parts reactive alumina powder, 15-25 parts iron oxide brown pigment, 520-580 parts deionized water, and 2.5-3.5 parts sodium tripolyphosphate.

5. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The cementitious binder is prepared from 500 parts silicate cement, 150 parts refined quartz sand and 180 parts deionized water by weight.

6. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The porcelain suspension insulator is a 120kN disc-shaped porcelain suspension insulator, and the iron cap and the steel foot are 120kN ball-and-socket connectors. The exposed glazed area of ​​the porcelain component is 2000-2500 cm². 2 .

7. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The exposed glazed area of ​​the porcelain piece is 2300 cm². 2 The amount of the uncomplexed highly dispersed boehmite anchoring sol to be sprayed is 18-22g, the nozzle diameter is 1mm, the spraying pressure is 0.25MPa, the nozzle of the spray gun is 20cm away from the surface of the ceramic blank, the ceramic blank is rotated at 20r / min, after spraying the ceramic blank is placed at 35℃ for 15-25min, and then dried at 55-65℃ for 25-35min.

8. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The exposed glazed area of ​​the porcelain piece is 2300 cm². 2 The modified boron-aluminum-silicon transition sol is sprayed twice onto the glazed area of ​​the ceramic blank after treatment with uncomplexed highly dispersed boehmite anchoring sol. The first spray is 28-32g, and the blank is left at 25℃ for 8-10 minutes after spraying. The second spray is 24-28g, and the blank is left at 25℃ for 10-14 minutes after spraying.

9. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The segmented drying process involves drying at 38-42℃ for 25-35 minutes, at 70-80℃ for 80-100 minutes, and at 105-115℃ for 50-70 minutes in sequence.

10. The fracture-resistant, high-toughness porcelain suspension insulator according to claim 1, characterized in that, The glazing and firing process involves: spraying a raw glaze slurry onto the glazing area of ​​the porcelain blank and drying it to obtain a glazed porcelain blank; firing the glazed porcelain blank to obtain a fired porcelain piece; and ensuring the exposed glazed area of ​​the porcelain piece is 2300 cm². 2 The amount of the glaze slurry applied is 230-250g, the spraying pressure is 0.25MPa, the nozzle diameter is 1mm, the distance between the spray gun outlet and the surface of the ceramic blank is 20cm, the ceramic blank is rotated at 20r / min, and after spraying, it is dried at 80℃ for 120min; the firing process is as follows: the glazed ceramic blank is placed in the electric porcelain firing kiln, and the temperature is raised from 25℃ to 200℃ in an oxidizing atmosphere at a heating rate of 30℃ / h, and held for 2h. Continue heating to 600℃ at a rate of 60℃ / h and hold for 2 hours; continue heating to 980℃ at a rate of 90℃ / h and hold for 1 hour; continue heating to 1260℃ to 1300℃ at a rate of 70℃ / h and hold for 2.5 to 3.5 hours; then reduce to 1000℃ at a rate of 60℃ / h and hold for 1 hour; then reduce to 600℃ at a rate of 80℃ / h, and then cool with the kiln to below 80℃ before exiting the kiln.