A method for preparing an insulator ceramic body

Abstract

The application belongs to the technical field of electrical insulator materials, and particularly relates to a preparation method of an insulator ceramic body. The preparation method comprises the following steps: raw material proportioning, raw material pretreatment and particle preparation, gradient filling, preforming, secondary pressing, body repairing, sectional sintering and cooling. Through optimization of raw material composition, filling and forming processes and the like, the core performances of the insulator, such as zero value resistance and pollution flashover resistance, can be improved, the biological waste is used for resource utilization, the sintering temperature is reduced, the waste heat is fully utilized, the energy consumption and carbon emission are significantly reduced, and the green and low-carbon production process is provided.

Description

Technical Field

[0001] This invention belongs to the field of electrical insulator materials technology, and specifically relates to a method for preparing an insulator ceramic blank. Background Technology

[0002] Ceramic insulators are widely used in power systems, and are extensively installed in substations, converter station structures, and transmission line towers. Insulators must possess both good electrical performance and sufficient mechanical strength, making the quality of the ceramic body crucial.

[0003] However, existing ceramic insulators have some prominent problems during long-term operation. For example, the ceramic components of insulators are continuously subjected to complex conditions such as strong electric fields, mechanical stress, alternating heating and cooling, and moisture intrusion during operation, which can easily lead to a decrease in the insulation resistance of the insulator head, forming a zero-value insulator. The presence of zero-value insulators significantly increases the probability of flashover due to pollution and flashover under overvoltage, seriously threatening power grid safety. Once the insulator string suffers a lightning strike or other cause of flashover, most of the energy is released through the discharge channel inside the ceramic component of the low-value insulator head, and the generated heat causes the insulator to crack and detach, leading to a string breakage accident. Secondly, insulators are installed outdoors, and their surfaces are prone to dust and other impurities. Rainy days can easily cause flashover due to pollution, and the dirt can easily form a conductive film under humid conditions, greatly reducing the insulation level of the insulator. Furthermore, leakage current and lightning arcs under polluted and humid conditions can cause insulator aging. When a zero-value insulator exists in an insulator string, power frequency flashover or lightning strikes will generate a large current flowing through the defective insulator. The strong thermal effect often causes the steel cap of the suspension insulator to crack or detach, resulting in a string drop accident. In addition, existing processing techniques often use traditional high-temperature sintering and drying processes, and use natural minerals such as potassium feldspar as fluxing agents, which is not only more energy-intensive and less efficient, but also causes environmental damage.

[0004] Therefore, developing a preparation process for insulator ceramic blanks that are resistant to zero values, highly resistant to pollution, and green and low-carbon is of practical significance. Summary of the Invention

[0005] To address the aforementioned shortcomings, this invention provides a method for preparing ceramic blanks for insulators. This method can improve the core properties of insulators, such as zero resistance and flashover resistance, and has low energy consumption and carbon emissions, making it a green and low-carbon production process.

[0006] The purpose of this invention is to provide a method for preparing an insulator ceramic blank, the method comprising the following steps: Step 1: Prepare ceramic ligand raw materials according to weight proportions, including base material, functional material A, and functional material B. The base material includes 30-50 parts quartz powder, 18-24 parts bauxite, 15-20 parts kaolin, 2-4 parts talc, 1-2 parts titanium dioxide, and 5-10 parts recycled waste ceramic powder. Functional material A includes 5-8 parts silicon carbide micro powder, and functional material B includes 4-9 parts bovine bone ash and 1.5-3 parts rice husk ash. The main component of quartz powder is silicon dioxide, and the main component of bauxite is alumina. This invention uses silicon dioxide... Silicon carbide, the main skeletal component of ceramics, reacts with alumina to form mullite crystals, enhancing the strength and hardness of the ceramic body. Talc, primarily composed of magnesium oxide, promotes densification and improves thermal shock resistance. The added titanium dioxide further enhances photocatalysis, lowers sintering temperature, and improves stain resistance by utilizing its self-cleaning photocatalytic properties. The use of recycled waste ceramic powder not only partially replaces quartz powder and alumina raw materials but also utilizes the existing mullite crystal structure as a seed crystal to lower the sintering activation energy, promoting crystallization and densification, and enabling the recycling of production waste. By incorporating silicon carbide micropowder with semi-insulating conductive properties at room temperature, a sustained micro-Joule heating effect keeps the ceramic surface temperature above the dew point temperature, preventing moisture condensation and physically eliminating the humid environment caused by zero dew. Even in foggy or rainy weather, the ceramic surface remains dry, preventing the formation of a conductive water film. Bovine bone ash, with its high calcium oxide content, reacts with the silicon dioxide in the ceramic body. Alumina forms a low eutectic compound, which lowers the softening temperature of silica. The silica in rice husk ash is in an amorphous nano-state with extremely high specific surface area and reactivity, which can accelerate the solid-phase reaction. By using bovine bone ash and rice husk ash as biomass composite flux, a CaO-SiO2 low eutectic system is formed during sintering, with a eutectic temperature of about 1100℃, which is about 100℃ lower than the traditional potassium feldspar flux system. This not only reduces the sintering temperature but also enables the resource utilization of waste and reduces the use of minerals.

[0007] Step 2: After pretreatment of functional material B, it is mixed with base material, ball milled, iron removed, and spray granulated to obtain base particles; after high-energy ball milling activation treatment of functional material A, starch is added and granulated to obtain functional material particles. Step 3: In the isostatic pressing mold, the insulator is filled in a gradient manner in three layers: surface layer, transition layer, and core. The surface layer accounts for 15-20% of the blank wall thickness, the transition layer accounts for 30-40% of the blank wall thickness, and the core is the remaining thickness. Gradient filling is adopted according to the different functional requirements of different parts of the material. This makes the surface layer of the insulator have self-heating and photocatalytic functions, the core maintains high insulation, and the design of the transition layer can avoid excessive abrupt changes in silver composition between the surface layer and the core, which can cause thermal expansion mismatch and stress concentration.

[0008] Step 4: Seal the mold after gradient filling and place it in a cold isostatic press for pre-forming at a pressure of 80-120MPa for 2-4 minutes; Step 5: Remove the preformed blank from the mold, place it in a special warm isostatic pressing packaging bag, vacuum seal it, and then place it in a warm isostatic press. Perform secondary pressing at a temperature of 60-80℃ and a pressure of 100-130MPa for 5-10 minutes. This invention uses a two-stage warm isostatic pressing process, which can promote particle rearrangement, improve the uniformity of blank density, and the secondary pressing can also close the micro-cracks in the blank after cold isostatic pressing, effectively eliminating the zero value problem of insulators.

[0009] Step 6: Trim the green body after isostatic pressing to remove burrs and defects. The waste generated from trimming is collected and returned to Step 1 as raw material for waste porcelain recycling powder. Then, the green body is sent into a drying kiln heated by the residual heat of the kiln, with a drying temperature of 50-70℃ and a time of 18-30 hours. Step 7: Segmented sintering, including a low-temperature binder removal stage, a medium-temperature bisque firing stage, a high-temperature glaze firing stage, and in-situ fluorination treatment; first, sintering at a low temperature slowly removes the binder and loss on ignition components, which can avoid cracks caused by rapid binder removal and form uniform micropores in situ; then, medium-temperature bisque firing is used, during which the loss on ignition components are completely burned off, and early densification of the green body is promoted. At the same time, a micro-oxide layer is formed on the SiC surface; finally, high-temperature calcination is used to densify the ceramic body and increase its strength; at the same time, by introducing a trace amount of hydrogen fluoride, Si-F bonds are formed on the glaze surface to form a permanent hydrophobic layer, further enhancing the self-cleaning properties of the green body.

[0010] Step 8: Cool to room temperature, and you will get the product.

[0011] Preferably, in step one of the above technical solution, the D of the silicon carbide micro powder 50 It is 1-3μm.

[0012] Preferably, in step one of the above technical solution, the mass ratio of bovine bone ash to rice husk ash in functional material B is 2-4:1, wherein the CaO content in the bovine bone ash is 70-75%, and the amorphous SiO2 content in the rice husk ash is 85-95%. This technical solution transforms slaughterhouse waste bovine bones and agricultural waste rice husks into a high-value biomass composite flux. The combination of CaO from bovine bone ash and amorphous SiO2 from rice husk ash provides both fluxing and silicon supplementation functions, reducing raw material costs and solving the environmental problems of agricultural / livestock waste disposal, thus turning waste into treasure.

[0013] Preferably, in step two of the above technical solution, the pretreatment step of the functional material B is as follows: waste bovine bones are washed, degreased, calcined at 700-800℃, and then ground to obtain bovine bone ash; agricultural waste rice husks are calcined at 500-700℃ to obtain rice husk ash; bovine bone ash and rice husk ash are mixed at a mass ratio of 2-4:1, ball-milled for 2-4 hours, and the particle size reaches D50≤10μm, thus obtaining the final product.

[0014] Preferably, in step two of the above technical solution, the preparation process of the basic particles is as follows: Quartz powder, bauxite, kaolin, talc, titanium dioxide, and functional material B are mixed according to the formula and loaded into a ball mill. 40-50% of the total mass of the raw materials is added to deionized water. Alumina balls are used as the grinding medium, and the ball milling time is 18-24 hours to make the fineness of the raw materials reach a residue of no more than 0.3% on a 10,000-mesh sieve. Then, the ceramic slurry is treated by magnetic separation to remove iron, so that the Fe2O3 content in the slurry is controlled below 0.8%. After passing through a 200-mesh sieve, the slurry is sent to a spray drying tower for spray granulation, using the waste heat of the kiln as a heat source. The inlet temperature is 200-250℃, and the outlet temperature is 90-110℃ to obtain the basic particles. The particle size of the basic particles is 80-150μm, and the water content is 2-4%.

[0015] Preferably, in step two of the above technical solution, the activation process of the functional material A is as follows: First, silicon carbide micro powder is weighed according to the formula amount, and 0.5-1.5% of polycarboxylic acid dispersant is added to the powder. The powder is then loaded into a high-energy ball mill for activation treatment. The ball milling speed is 300-400 rpm, and the activation time is 4-6 hours. Then, the activated functional powder is mixed with starch accounting for 5-8% of the powder and fed into a granulator for granulation. The granules are then sieved to obtain functional material particles. The particle size of the functional material particles is 100-200 μm, and the moisture content is 1-3%.

[0016] Preferably, in step three of the above technical solution, the volume ratio of basic particles to functional material particles in the surface layer is 0.8-1.2:1, the volume ratio of basic particles to functional material particles in the transition layer is 2.5-3.5:1, and the core is composed entirely of basic particles. Gradient layering ensures that the surface of the ceramic body is rich in silicon carbide functional components, achieving self-heating and dehumidification. The reduced proportion of functional material particles in the transition layer avoids thermal expansion mismatch and stress concentration caused by abrupt changes in silver composition between the surface layer and the core. The core contains only basic particle components, maintaining high insulation and avoiding the influence of functional components on the overall insulation.

[0017] Preferably, in step seven of the above technical solution, the process of the low-temperature adhesive removal section is as follows: under a weak oxidizing atmosphere, the temperature is increased from room temperature to 400-500℃ at a rate of 1.5-2.5℃ / min, and held for 0.5-1h; the oxygen content in the weak oxidizing atmosphere is 5-10%.

[0018] Preferably, in step seven of the above technical solution, the process of the medium-temperature calcination section is as follows: under a reducing atmosphere, the temperature is increased to 850-1020℃ at a rate of 3-5℃ / min, and held for 2-3 hours; the CO content in the reducing atmosphere is 2-5%.

[0019] Preferably, in step seven of the above technical solution, the process of the high-temperature glaze firing section is as follows: under a weak reduction to neutral atmosphere, the temperature is increased to 1180-1240℃ at a rate of 2-4℃ / min and held for 2-3 hours; in the last 0.5-1 hours of holding, 0.1-0.5% of hydrogen fluoride gas in total atmosphere volume is introduced into the furnace.

[0020] Advantages compared to existing technologies: 1. This invention optimizes the raw material ratio to control the alumina content in the ceramic body at a low level, which can effectively reduce the weight of the product while ensuring mechanical strength; it utilizes the self-heating effect of silicon carbide to make the surface temperature of the ceramic body higher than the ambient temperature, thereby achieving the purpose of dehumidification. At the same time, by controlling its dosage, it ensures that excessive leakage current is effectively avoided, which would affect the insulation performance.

[0021] 2. This invention divides each raw material into two parts, which are granulated independently and then filled in a gradient layer and subjected to double isostatic pressing. This results in the surface layer of the ceramic body being rich in silicon carbide functional components, achieving self-heating and moisture-removing functions, while the core is rich in basic particle components, maintaining high insulation and avoiding the influence of functional components on the overall insulation. The double temperature isostatic pressing process promotes particle rearrangement, improves the uniformity of body density, eliminates microcracks, blocks moisture intrusion, and avoids zero-value problems.

[0022] 3. This invention employs a segmented controlled atmosphere sintering process, with slow low-temperature debinding to ensure complete combustion of organic matter and the formation of micropores; medium temperature promotes micro-oxidation of surface silicon carbide to form a silicon dioxide oxide film, which can ensure the micro-Joule heating effect and avoid excessive current. At the same time, the CaO from bovine bone ash and the amorphous SiO2 from rice husk ash form a CaO-SiO2 eutectic system, which can promote early densification of the green body; high temperature further promotes the densification of the ceramic body and improves its strength.

[0023] 4. This invention uses bovine bone ash and rice husk ash as biomass composite flux to replace traditional potassium feldspar, and waste porcelain recycling powder as seed crystals. Simultaneously, it incorporates nano-sized amorphous SiO2 from rice husk ash. Utilizing the CaO-SiO2 eutectic system, the partial glass phase in the waste porcelain recycling powder, and the high specific surface area and high reactivity of the nano-sized amorphous SiO2 in the rice husk ash, the synergistic effect of these three elements can reduce the glazing temperature from the traditional 1250-1310℃ to 1180-1240℃, a reduction of 80-130℃, achieving energy conservation and emission reduction. At the same time, it realizes the resource utilization of agricultural waste bovine bone ash and rice husk ash.

[0024] 5. This invention fully utilizes the waste heat generated by the kiln system in a graded manner, reducing additional energy consumption, making it green, low-carbon, and environmentally friendly, and also helping to reduce costs. Detailed Implementation

[0025] The above-described technical features of the present invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. However, the present invention is not limited to these embodiments, nor are these embodiments limited in any way.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the formulations involved in the following examples are all commercially available products that can be purchased from the market.

[0027] The present invention will be further described in detail below with reference to embodiments: Example 1 A method for preparing an insulator ceramic blank includes the following steps: Step 1: Prepare ceramic ligand raw materials according to the following weight proportions, including base material, functional material A and functional material B. The base material includes 28 parts of quartz powder, 20 parts of bauxite, 18 parts of kaolin, 3 parts of talc, 1 part of titanium dioxide and 8 parts of waste porcelain recycling powder. Functional material A is 7 parts of silicon carbide micro powder. Functional material B includes 6 parts of ox bone ash (CaO content of 72%) and 3 parts of rice husk ash (amorphous SiO2 content of 90%). Step 2: First, pre-treat functional material B: clean, degrease, calcine at 750℃ and grind to obtain bovine bone ash; calcine agricultural waste rice husks at 600℃ to obtain rice husk ash; mix bovine bone ash and rice husk ash at a mass ratio of 2:1, ball mill for 3 hours until the particle size reaches D50≤10μm, and then obtain the product. Then, quartz powder, bauxite, kaolin, talc, titanium dioxide, and pretreated functional material B are mixed according to the formula and loaded into a ball mill. Deionized water of 45% of the total mass of raw materials is added, and alumina balls are used as the grinding medium. The ball milling time is 20 hours to make the fineness of the raw materials reach a residue of no more than 0.3% on a 10,000-mesh sieve. Then, the ceramic slurry is treated by magnetic separation to remove iron, so that the Fe2O3 content in the slurry is controlled below 0.8%. After passing through a 200-mesh sieve, the slurry is sent to a spray drying tower for spray granulation, using the waste heat of the kiln as the heat source. The inlet temperature is 230℃ and the outlet temperature is 100℃ to obtain basic particles (particle size between 80-150μm, moisture content of 3%). Subsequently, silicon carbide micro powder was weighed according to the formula, and sodium polycarboxylate (1% of the total weight of the powder) was added. The powder was then placed in a high-energy ball mill for activation treatment at a ball mill speed of 300 rpm for 6 hours. The activated functional powder was then mixed with starch (6% of the total weight of the powder) and fed into a granulator for granulation. The granules were then sieved to obtain functional material particles (particle size between 100-200 μm, moisture content of 2%). Step 3: In the isostatic pressing mold, the surface layer, transition layer and core are filled in a gradient. The surface layer (the volume ratio of basic particles to functional particles is 1:1) accounts for 18% of the wall thickness of the blank, the transition layer (the volume ratio of basic particles to functional particles is 3:1) accounts for 35% of the wall thickness of the blank, and the core (basic particles) is the remaining thickness. Step 4: Seal the mold after gradient filling and place it in a cold isostatic press for pre-forming at 100MPa pressure for 3 minutes; Step 5: Remove the preformed blank from the mold, put it into a special packaging bag for warm isostatic pressing, vacuum seal it, and then place it in a warm isostatic press for secondary pressing at a temperature of 70℃, a pressure of 120MPa, and a holding time of 7 minutes. Step 6: Trim the green body after isostatic pressing to remove burrs and defects. The waste generated from trimming is collected and returned to Step 1 as raw material for waste porcelain recycling powder. Then, the green body is sent into a drying kiln heated by the residual heat of the kiln, and the drying temperature is 60℃ for 25 hours. Step 7: Segmented sintering, including a low-temperature debinding section, a medium-temperature bisque firing section, a high-temperature glaze firing section, and in-situ fluorination treatment; among which, The process for the low-temperature adhesive removal section is as follows: under a weak oxidizing atmosphere (oxygen content of 7%), the temperature is increased from room temperature to 450℃ at a rate of 2℃ / min, and held for 0.5h. The process for the medium-temperature calcination section is as follows: under a reducing atmosphere (CO content of 3%), the temperature is increased to 950℃ at a rate of 4℃ / min and held for 2.5h. The process for the high-temperature glaze firing section is as follows: under a weak reduction to neutral atmosphere, the temperature is increased to 1200℃ at a rate of 3℃ / min and held for 2.5h. The in-situ fluorination treatment involves introducing hydrogen fluoride gas at a total volume of 0.3% into the furnace during the last 0.5 hours of heat preservation. Step 8: Cool to room temperature, and you will get the product.

[0028] Example 2 A method for preparing an insulator ceramic blank includes the following steps: Step 1: Prepare ceramic ligand raw materials according to the following weight proportions, including base material, functional material A and functional material B. The base material includes 35 parts of quartz powder, 22 parts of bauxite, 15 parts of kaolin, 4 parts of talc, 1.5 parts of titanium dioxide and 5 parts of waste ceramic powder. Functional material A is 5 parts of silicon carbide micro powder. Functional material B includes 8 parts of ox bone ash (CaO content of 72%) and 2.7 parts of rice husk ash (amorphous SiO2 content of 90%). Step 2: First, pre-treat functional material B: clean, degrease, calcine at 700℃ and grind to obtain bovine bone ash; calcine agricultural waste rice husks at 500℃ to obtain rice husk ash; mix bovine bone ash and rice husk ash at a mass ratio of 3:1, ball mill for 4 hours until the particle size reaches D50≤10μm, and then obtain the product. Then, quartz powder, bauxite, kaolin, talc, titanium dioxide, and pretreated functional material B are mixed according to the formula and loaded into a ball mill. 40% of the total mass of raw materials is added with deionized water. Alumina balls are used as the grinding medium, and the milling time is 18 hours to make the fineness of the raw materials reach a residue of no more than 0.3% on a 10,000-mesh sieve. The ceramic slurry is then treated by a magnetic separator to remove iron, so that the Fe2O3 content in the slurry is controlled below 0.8%. After passing through a 200-mesh sieve, the slurry is sent to a spray drying tower for spray granulation, using the waste heat of the kiln as a heat source. The inlet temperature is 200℃ and the outlet temperature is 90℃ to obtain basic particles (particle size between 80-150μm, moisture content of 4%). Subsequently, silicon carbide micro powder was weighed according to the formula, and sodium polycarboxylate (0.5% of the total weight of the powder) was added. The powder was then placed in a high-energy ball mill for activation treatment at a ball mill speed of 350 rpm for 5 hours. The activated functional powder was then mixed with starch (5% of the total weight of the powder) and fed into a granulator for granulation. The granules were then sieved to obtain functional material particles (particle size between 100-200 μm, moisture content of 3%). Step 3: In the isostatic pressing mold, the surface layer, transition layer and core are filled in a gradient. The surface layer (the volume ratio of basic particles to functional particles is 0.8:1) accounts for 20% of the wall thickness of the blank, the transition layer (the volume ratio of basic particles to functional particles is 2.5:1) accounts for 40% of the wall thickness of the blank, and the core (basic particles) is the remaining thickness. Step 4: Seal the mold after gradient filling and place it in a cold isostatic press for pre-forming at 80MPa pressure for 4 minutes; Step 5: Remove the preformed blank from the mold, put it into a special packaging bag for warm isostatic pressing, vacuum seal it, and then place it in a warm isostatic press for secondary pressing at a temperature of 60℃ and a pressure of 130MPa for 5 minutes. Step 6: Trim the green body after isostatic pressing to remove burrs and defects. The waste generated from trimming is collected and returned to Step 1 as raw material for waste porcelain recycling powder. Then, the green body is sent into a drying kiln heated by the residual heat of the kiln, and the drying temperature is 50℃ for 30 hours. Step 7: Segmented sintering, including a low-temperature debinding section, a medium-temperature bisque firing section, a high-temperature glaze firing section, and in-situ fluorination treatment; among which, The process for the low-temperature adhesive removal section is as follows: under a weak oxidizing atmosphere (oxygen content of 7%), the temperature is increased from room temperature to 400℃ at a rate of 1.5℃ / min and held for 1 hour. The process for the medium-temperature calcination section is as follows: under a reducing atmosphere (CO content of 3%), the temperature is increased to 850℃ at a rate of 3℃ / min and held for 3 hours; The process for the high-temperature glaze firing section is as follows: under a weak reduction to neutral atmosphere, the temperature is increased to 1180℃ at a rate of 2℃ / min and held for 3 hours; In-situ fluorination treatment involves introducing hydrogen fluoride gas at a total volume of 0.1% into the furnace during the last hour of heat preservation. Step 8: Cool to room temperature, and you will get the product.

[0029] Example 3 A method for preparing an insulator ceramic blank includes the following steps: Step 1: Prepare ceramic ligand raw materials according to the following weight proportions, including base material, functional material A and functional material B. The base material includes 50 parts of quartz powder, 24 parts of bauxite, 20 parts of kaolin, 4 parts of talc, 2 parts of titanium dioxide and 10 parts of waste porcelain recycling powder. Functional material A is 8 parts of silicon carbide micro powder. Functional material B includes 8 parts of ox bone ash (CaO content of 72%) and 3 parts of rice husk ash (amorphous SiO2 content of 90%). Step 2: First, pre-treat functional material B: clean, degrease, calcine at 800℃ and grind to obtain bovine bone ash; calcine agricultural waste rice husks at 700℃ to obtain rice husk ash; mix bovine bone ash and rice husk ash at a mass ratio of 3:1, ball mill for 2 hours until the particle size reaches D50≤10μm, and then obtain the product. Then, quartz powder, bauxite, kaolin, talc, titanium dioxide, and pretreated functional material B are mixed according to the formula and loaded into a ball mill. Deionized water equal to 50% of the total mass of the raw materials is added. Alumina balls are used as the grinding medium, and the milling time is 24 hours to ensure that the fineness of the raw materials reaches a residue of no more than 0.3% on a 10,000-mesh sieve. The ceramic slurry is then subjected to iron removal treatment by a magnetic separator to control the Fe2O3 content in the slurry to below 0.8%. After passing through a 200-mesh sieve, the slurry is sent to a spray drying tower for spray granulation, using the waste heat of the kiln as a heat source. The inlet temperature is 250℃ and the outlet temperature is 110℃ to obtain basic particles (particle size between 80-150μm, moisture content of 2%). Subsequently, silicon carbide micro powder was weighed according to the formula, and sodium polycarboxylate, accounting for 1.5% of the total weight of the powder, was added and loaded into a high-energy ball mill for activation treatment. The ball milling speed was 400 rpm, and the activation was carried out for 4 hours. Then, the activated functional powder was mixed with starch, accounting for 8% of the total weight of the powder, and fed into a granulator for granulation. The functional material particles were obtained by sieving (particle size between 100-200 μm, moisture content of 1%). Step 3: In the isostatic pressing mold, the surface layer, transition layer and core are filled in a gradient. The surface layer (the volume ratio of basic particles to functional particles is 1.2:1) accounts for 15% of the wall thickness of the blank, the transition layer (the volume ratio of basic particles to functional particles is 3.5:1) accounts for 30% of the wall thickness of the blank, and the core (basic particles) is the remaining thickness. Step 4: Seal the mold after gradient filling and place it in a cold isostatic press for pre-forming at a pressure of 120MPa for 2 minutes. Step 5: Remove the preformed blank from the mold, put it into a special packaging bag for warm isostatic pressing, vacuum seal it, and then place it in a warm isostatic press for secondary pressing at 80°C and 100MPa for 10 minutes. Step 6: Trim the green body after isostatic pressing to remove burrs and defects. The waste generated from trimming is collected and returned to Step 1 as raw material for waste porcelain recycling powder. Then, the green body is sent into a drying kiln heated by the residual heat of the kiln, and the drying temperature is 70℃ for 18 hours. Step 7: Segmented sintering, including a low-temperature debinding section, a medium-temperature bisque firing section, a high-temperature glaze firing section, and in-situ fluorination treatment; among which, The process for the low-temperature adhesive removal section is as follows: under a weak oxidizing atmosphere (oxygen content of 7%), the temperature is increased from room temperature to 500℃ at a rate of 2.5℃ / min, and held for 0.5h. The process for the medium-temperature calcination section is as follows: under a reducing atmosphere (CO content of 3%), the temperature is increased to 1020℃ at a rate of 5℃ / min and held for 2 hours; The process for the high-temperature glaze firing section is as follows: under a weak reduction to neutral atmosphere, the temperature is increased to 1240℃ at a rate of 4℃ / min and held for 2 hours; The in-situ fluorination treatment involves introducing hydrogen fluoride gas at a total volume of 0.5% into the furnace during the last 0.5 hours of heat preservation. Step 8: Cool to room temperature, and you will get the product.

[0030] Comparative Example 1 A method for preparing an insulator ceramic blank, the method differs from that of Example 1 in that, in step one: functional material B is potassium feldspar, and in step seven: the glazing temperature is 1280℃, the rest is the same as in Example 1.

[0031] Comparative Example 2 A method for preparing an insulator ceramic blank, the method differs from that in Example 1 in that, in step one: functional material A is an equal amount of quartz powder, and the rest is the same as in Example 1.

[0032] Comparative Example 3 A method for preparing an insulator ceramic blank, the method differing from Example 1 in that step two is as follows: waste bovine bones are cleaned, degreased, calcined at 750℃, and then ground to obtain bovine bone ash; agricultural waste rice husks are calcined at 600℃ to obtain rice husk ash; bovine bone ash and rice husk ash are mixed at a mass ratio of 2:1, ball-milled for 3 hours until the particle size reaches D50≤10μm, thus obtaining the blank; there is no particle preparation step, and the raw materials are directly mixed and then filled, otherwise the same as in Example 1.

[0033] Comparative Example 4 A method for preparing an insulator ceramic blank, the method differs from Example 1 in that step four is omitted, while the rest is the same as in Example 1.

[0034] Comparative Example 5 A method for preparing an insulator ceramic blank, the method differing from Example 1 in that step seven is: in an air atmosphere, the heating rate is 4℃ / min, bisque firing is carried out at 950℃ for 3.5h, glazing is applied after cooling, sintering is carried out at 1310℃ for 2.5h, furnace cooling is carried out to room temperature, and the rest is the same as in Example 1.

[0035] Comparative Example 6 A method for preparing an insulator ceramic blank, using a traditional siliceous ceramic formula (70% SiO2, 22% Al2O3, potassium feldspar flux), fired in a single air atmosphere at a glaze firing temperature of 1280℃.

[0036] Test case The products prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to performance tests, and the results are shown in Table 1. The flexural strength was tested according to the relevant methods in GB / T 4741-1999, the water absorption rate according to the relevant methods in GB / T 3299-2011, the bulk density according to the relevant methods in GB / T 25995-2010, the thermal shock resistance according to the relevant methods in GB / T 37246-2018, and the surface contact angle according to the relevant methods in GB / T 30447-2013.

[0037] Table 1 Test Results

[0038] As can be seen from the results in Table 1, the ceramic bodies prepared by the method of the present invention in Examples 1-3 have high flexural strength and good strength, low water absorption to ensure long-term electrical stability, low density to achieve a certain degree of lightweighting, good thermal shock resistance (no cracking at a temperature difference of 200℃), large surface contact angle and good hydrophobicity, and are not easily affected by moisture. At the same time, combined with its low water absorption, the self-heating and moisture-removing effect of silicon carbide and the self-cleaning effect of titanium oxide, the zero-value problem and the anti-flashover problem can be effectively avoided, resulting in excellent overall performance.

[0039] In Comparative Example 1, potassium feldspar was used as a flux. Although the overall performance of the ceramic body was not significantly different, it required a higher sintering temperature. In Comparative Example 2, functional material A was quartz powder, which had a high water absorption rate and was prone to moisture absorption. In Comparative Example 3, the raw materials were not gradient-filled, and the raw material composition of each part was consistent. Although the bending strength and overall density were not significantly affected, the insulation was poor, and problems such as zero values ​​may occur. In Comparative Example 4, a single cold isostatic pressing was used, which resulted in uneven pressing and poor thermal shock resistance. In Comparative Example 5, two sintering processes were used, resulting in a higher degree of densification, greater density, and a small surface contact angle, but poor hydrophobicity and stain resistance. In Comparative Example 6, the ceramic body prepared by the traditional silica ceramic formula and method not only had lower strength, but also poor water absorption and hydrophobicity, poor moisture and stain resistance, and a higher sintering temperature, resulting in greater energy consumption.

[0040] Furthermore, the preparation method of this invention uses bovine bone ash and rice husk ash as a composite flux, and recycled waste ceramic powder as a raw material, realizing the resource utilization of waste. Simultaneously, by utilizing the CaO-SiO2 eutectic system in the aforementioned raw materials, the partial glass phase in the recycled waste ceramic powder, and the reactivity of nano-amorphous SiO2, the sintering temperature can be reduced by approximately 100°C, thus reducing energy consumption and carbon emissions. In addition, the waste heat generated by the kiln system is fully utilized for drying and other processes, reducing additional energy consumption by approximately 30% compared to traditional ceramic body processes. This demonstrates that the optimized preparation method of this invention is a relatively green and low-carbon production process, which is beneficial to the needs of sustainable development.

[0041] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an insulator ceramic blank, characterized in that, The preparation method includes the following steps: Step 1: Prepare ceramic ligand raw materials according to the following weight proportions, including base material, functional material A, and functional material B. The base material includes 30-50 parts of quartz powder, 18-24 parts of bauxite, 15-20 parts of kaolin, 2-4 parts of talc, 1-2 parts of titanium dioxide, and 5-10 parts of recycled waste porcelain powder. Functional material A includes 5-8 parts of silicon carbide micro powder, and functional material B includes 4-9 parts of ox bone ash and 1.5-3 parts of rice husk ash. Step 2: After pretreatment of functional material B, it is mixed with base material, ball milled, iron removed, and spray granulated to obtain base particles; after high-energy ball milling activation treatment of functional material A, starch is added and granulated to obtain functional material particles. Step 3: In the isostatic pressing mold, the surface layer, transition layer and core are filled in a gradient manner. The surface layer accounts for 15-20% of the wall thickness of the blank, the transition layer accounts for 30-40% of the wall thickness of the blank, and the core is the remaining thickness. Step 4: Seal the mold after gradient filling and place it in a cold isostatic press for pre-forming at a pressure of 80-120MPa for 2-4 minutes; Step 5: Remove the preform from the mold, put it into a special warm isostatic pressing packaging bag, vacuum seal it, and then place it in a warm isostatic press for secondary pressing at a temperature of 60-80℃ and a pressure of 100-130MPa for 5-10 minutes. Step 6: Trim the green body after isostatic pressing to remove burrs and defects. The waste generated from trimming is collected and returned to Step 1 as raw material for waste porcelain recycling powder. Then, the green body is sent into a drying kiln heated by the residual heat of the kiln, with a drying temperature of 50-70℃ and a time of 18-30 hours. Step 7: Segmented sintering, including low-temperature debinding section, medium-temperature bisque firing section, high-temperature glaze firing section, and in-situ fluorination treatment; Step 8: Cool to room temperature, and you will get the product.

2. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step one, the D of the silicon carbide micro powder 50 It is 1-3μm.

3. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step one, the mass ratio of bovine bone ash to rice husk ash in functional material B is 2-4:1, wherein the bovine bone ash contains 70-75% CaO and the rice husk ash contains 85-95% amorphous SiO2.

4. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step two, the pretreatment steps for functional material B are as follows: waste bovine bones are washed, degreased, calcined at 700-800℃, and then ground to obtain bovine bone ash; agricultural waste rice husks are calcined at 500-700℃ to obtain rice husk ash; bovine bone ash and rice husk ash are mixed at a mass ratio of 2-4:1, ball-milled for 2-4 hours, and the particle size reaches D50≤10μm, thus obtaining the final product.

5. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step two, the preparation process of the basic particles is as follows: Quartz powder, bauxite, kaolin, talc, titanium dioxide, and functional material B are mixed according to the formula, and then ball-milled in a ball mill for 18-24 hours. After removing iron and sieving, the slurry is sent to a spray drying tower for spray granulation, using the waste heat of the kiln as a heat source. The inlet temperature is 200-250℃, and the outlet temperature is 90-110℃ to obtain the basic particles. The particle size of the basic particles is 80-150μm, and the water content is 2-4%.

6. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step two, the activation process of functional material A is as follows: First, silicon carbide micro powder is weighed according to the formula, and 0.5-1.5% of polycarboxylic acid dispersant is added. After ball milling activation treatment for 4-6 hours, the activated functional powder is mixed with starch accounting for 5-8% of the total weight of the powder, and fed into a granulator for granulation. The granules are then sieved to obtain functional material particles. The particle size of the functional material particles is 100-200μm, and the moisture content is 1-3%.

7. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step three, the volume ratio of basic particles to functional material particles in the surface layer is 0.8-1.2:1, the volume ratio of basic particles to functional material particles in the transition layer is 2.5-3.5:1, and the core is composed entirely of basic particles.

8. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step seven, the process of the low-temperature adhesive removal section is as follows: under a weak oxidizing atmosphere, the temperature is increased from room temperature to 400-500℃ at a rate of 1.5-2.5℃ / min, and held for 0.5-1h; the oxygen content in the weak oxidizing atmosphere is 5-10%.

9. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step seven, the process of the medium-temperature calcination section is as follows: under a reducing atmosphere, the temperature is increased to 850-1020℃ at a rate of 3-5℃ / min, and held for 2-3 hours; the CO content in the reducing atmosphere is 2-5%.

10. The method for preparing an insulator ceramic blank according to claim 1, characterized in that, In step seven, the process of the high-temperature glaze firing section is as follows: under a weak reduction to neutral atmosphere, the temperature is raised to 1180-1240℃ at a rate of 2-4℃ / min and held for 2-3 hours; in the last 0.5-1 hour of holding, 0.1-0.5% of hydrogen fluoride gas in total atmosphere volume is introduced into the furnace.

Images