Preparation method of high-pressure ceramic sleeve containing in-situ whisker interface-prestressed synergistic reinforcement

Abstract

This invention belongs to the field of high-voltage porcelain bushing preparation technology, specifically relating to a method for preparing a high-voltage porcelain bushing containing an in-situ whisker interface-prestressed synergistic reinforcement. The preparation method consists of the following steps: (1) preparation of the bushing blank; (2) preparation of the transition layer; (3) preparation of the prestressed layer; (4) preparation of the bushing blank containing the glaze layer; (5) sintering. The high-voltage porcelain bushing containing the in-situ whisker interface-prestressed synergistic reinforcement prepared by the method of this invention has a tight bond between the in-situ generated whisker interface and the matrix, which plays a toughening role such as bridging and pull-out, significantly improving toughness and crack resistance. At the same time, the prestressed reinforcement can offset the thermal stress generated by the difference in thermal expansion, ensuring structural stability and insulation performance. It is also conducive to large-scale industrial production and can work stably in harsh environments of high voltage and high current, reducing the risk of accidents and ensuring the safety of the power grid and personnel.

Description

Technical Field

[0001] This invention belongs to the field of high-pressure ceramic sleeve preparation technology, specifically relating to a method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement. Background Technology

[0002] In the operation of power systems, high-voltage porcelain bushings bear the crucial responsibility of insulation and support when conductors pass through barriers. However, their working environment is extremely harsh, operating under high voltage and high current conditions for extended periods, which exposes the bushings to significant thermal expansion issues. When current flows through the conductor inside the bushing, a large amount of heat is generated, causing the conductor temperature to rise sharply. Meanwhile, the ambient temperature outside the bushing is relatively low. This temperature difference leads to a significant difference in thermal expansion between the conductor and the porcelain bushing. Because the coefficient of thermal expansion of the porcelain bushing material itself is relatively fixed, and the matching of thermal expansion coefficients between different material layers is poor, enormous thermal stress is generated between the layers during repeated temperature changes. This accumulated thermal stress can easily lead to cracks, delamination, and other damage to the bushing, severely affecting its insulation performance and structural stability, and even causing bushing explosions, threatening the safe operation of the power grid and the personal safety of personnel.

[0003] Currently, there are many shortcomings in addressing the thermal expansion and related toughness issues of high-voltage porcelain bushings. Directly using toughening additives, such as zirconium oxide and zirconium silicate, in the bushing matrix material results in toughening effects limited by the dosage, cost, dispersion degree, and bonding with the bushing raw material. Moreover, while these additives offer significant reinforcement, their toughening effect is limited, and some additives can even adversely affect the bushing's insulation, failing to adequately address the stress problems caused by thermal expansion.

[0004] Controlling the phase composition and microstructure of sleeve materials through sintering processes and raw material composition optimization mainly involves regulating the content and morphology of mullite. However, process optimization alone is insufficient to achieve the target composition and structure. The formation conditions of mullite are inconsistent with the firing conditions of the sleeve, making it difficult to achieve large-scale industrial production of sleeves that meet the target toughness requirements. Furthermore, the growth conditions for mullite morphology are demanding, and the sintering process can easily lead to uneven distribution of mullite content and significant morphological differences within the ceramic sleeve material, deteriorating the stability of material properties and resulting in poor performance in coping with stresses generated by thermal expansion.

[0005] Improving the toughness of ceramic sleeve materials by optimizing their structure, such as optimizing the sleeve shape and assembly structure, does not fundamentally improve the toughness of the material itself. It only adjusts the structure for different process conditions and assembly. When the usage conditions change, especially when the temperature changes significantly, the material itself still cannot withstand the stress caused by thermal expansion and cannot meet the toughness requirements.

[0006] In summary, existing technologies cannot effectively solve the thermal stress problem caused by differences in thermal expansion in high-pressure porcelain bushings, resulting in insufficient toughness and easy damage. Therefore, it is necessary to explore a new type of high-pressure porcelain bushing. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a high-pressure ceramic bushing containing an in-situ whisker interface-prestressed synergistic reinforcement. The high-pressure ceramic bushing prepared using this method exhibits excellent fracture toughness and crack resistance.

[0008] The method for preparing a high-pressure ceramic bushing containing an in-situ whisker interface-prestressed synergistic reinforcement body, as described in this invention, comprises the following steps:

[0009] (1) Preparation of casing blank

[0010] Industrial grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass and nano zirconium oxide are mixed evenly and then dry-milled in a planetary ball mill for 10 hours. Triethanolamine is added during ball milling. The resulting mixture is passed through a 200-mesh sieve and then spray-granulated through a 60-mesh sieve. The granulated particles are dried and isostatically pressed to obtain the casing blank.

[0011] (2) Preparation of the transition layer

[0012] ① Mix mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and mix evenly to prepare a mixture;

[0013] ② Add perfluoropolyether-based polysiloxane to the modified silica sol to prepare a modified silica sol containing perfluoropolyether-based polysiloxane;

[0014] ③ Add the mixture to the modified silica sol containing perfluoropolyether-based polysiloxane and stir for 15 minutes. Then add mullite particles and continue mixing for 15 minutes to obtain a transition layer slurry. Spray the transition layer slurry evenly onto the outer wall of the casing blank and dry it to prepare a casing blank containing a transition layer.

[0015] (3) Preparation of prestressed layer

[0016] Cordierite fine powder, nano-lanthanum oxide and nano-boron nitride fibers are mixed to prepare a premixed powder. Modified epoxy resin is added to the premixed powder and stirred evenly to prepare a prestressed layer slurry. The prestressed layer slurry is evenly sprayed onto the outer surface of the casing blank containing the transition layer and dried to prepare a casing blank containing the prestressed layer.

[0017] (4) Quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand and polyethylene glycol are mixed evenly, and then deionized water is added. The mixture is stirred with a high-speed dispersant to form a glaze slurry. The glaze slurry is applied to the outer surface and inner surface of the prestressed casing blank by electrostatic spraying. The casing blank with a glaze layer is prepared by step drying process.

[0018] (5) Sintering: The glazed sleeve blank is placed in a high-temperature furnace and heated to 1300℃ at a rate of 5℃ / min. It is then held for 2 hours for sintering to prepare a high-pressure ceramic sleeve containing in-situ whisker interface-prestress synergistic reinforcement.

[0019] in:

[0020] The casing blank in step (1) is composed of the following raw materials: industrial-grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass, nano-zirconia, and triethanolamine. The mass ratio of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay is 59.9: 34.9: 3.1: 2.1. The mass of high-purity modified water glass accounts for 0.6% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of nano-zirconia accounts for 0.5% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of triethanolamine accounts for 0.1% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay.

[0021] In step (1), the particle size of potassium feldspar powder is 200 mesh.

[0022] The industrial-grade bauxite mentioned in step (1) has the following chemical composition by mass percentage: Al2O3 78.3%, SiO2 12.1%, Fe2O3 2.0%, TiO2 2.4%, CaO 0.3%, MgO 0.2%, K2O 0.2%, Na2O 0.1%, and loss on ignition 4.4%.

[0023] The calcined kaolin described in step (1) has the following chemical composition by mass percentage: Al2O3 44.5%, SiO2 52.6%, Fe2O3 0.4%, TiO2 0.8%, CaO 0.2%, MgO 0.1%, K2O 0.2%, Na2O 0.1%, and loss on ignition 1.1%.

[0024] In step (1), the high-purity modified water glass is KN-40A produced by Foshan Kening New Material Technology Co., Ltd.

[0025] In step (1), alumina balls are used as the grinding medium during ball milling, and the ball-to-material ratio is 3:1.

[0026] In step (1), the drying temperature is 80℃, the drying time is 12h, the isostatic pressing pressure is 120MPa, and the holding time is 3min.

[0027] In step (1), industrial-grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, and high-purity modified water glass are put into a ball mill. The ball mill is turned on for initial mixing, and the mixing time is 10 minutes to ensure that the high-purity modified water glass is evenly attached to the surface of the main raw materials. Then, nano-zirconia toughening agent is added, and mixing continues for 10 minutes to ensure that nano-zirconia is initially dispersed in the material. Then, triethanolamine grinding aid is added, and then ball milling is performed. The planetary ball mill is set to dry ball milling mode, and the ball milling time is 10 hours to ensure that the material is fully ground and mixed. After the ball milling is completed, the mixture is taken out and passed through a 200-mesh sieve to remove any large particles that may exist and to ensure the fineness of the material. Then, the sieved material is sent to a spray granulation equipment for granulation. After granulation, it is passed through a 60-mesh sieve.

[0028] In step (1), industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay are used as the main raw materials. Among them, industrial-grade bauxite provides a large amount of alumina, which helps to form high-strength phases such as mullite, thereby improving mechanical strength and high-temperature resistance; calcined kaolin has good plasticity and sintering activity, which can reduce the firing temperature, promote the densification of the green body, and also participate in the formation of mullite phase to enhance structural stability; potassium feldspar powder acts as a flux, which lowers the melting temperature of the raw materials, forms a liquid phase during sintering, promotes particle bonding and diffusion, and improves the density and mechanical properties of the ceramic body; ball clay has strong plasticity, which improves the molding performance of the raw materials and ensures the adhesion, stability, and crack resistance of the green body. The synergistic effect of these main raw materials provides a suitable chemical composition and physical property basis for the ceramic sleeve matrix, ensuring that it has good mechanical strength, high-temperature resistance, and molding performance, and meets the basic performance requirements of high-pressure ceramic sleeves; high-purity modified water glass in the raw materials acts as a binder, nano-zirconia acts as a toughening agent, and triethanolamine acts as a grinding aid.

[0029] In step (2), the mass ratio of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder is 2.8-3.2 : 2.8-3.2 : 1.8-2.2 : 1.8-2.2; the mass of nano-yttrium oxide accounts for 0.8% of the total mass of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder.

[0030] The mullite particles mentioned in step (2) are spherical ceramic sand produced by Hunan Jiashun Huaxin Materials Co., Ltd., with a sphericity ≥95% and a particle size of 100 mesh; the mullite fine powder is produced by Luoyang Benteng Refractory Materials Co., Ltd., with a particle size of 1000 mesh, D 50 =12μm; ρ-Al2O3 has a particle size of 1000 mesh and a specific surface area of ​​250m².2 / g; amorphous silicon powder is α-Si, particle size is 1000 mesh, D 90 =2μm, manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd.; the particle size of nano-yttrium oxide is 30nm.

[0031] In step (2)①, first mix the mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and stir for 10 minutes to make it evenly dispersed in the fine powder system.

[0032] Step (2) ② Add perfluoropolyether-based polysiloxane to the modified silica sol and stir for 5 minutes to completely dissolve it, thus preparing a modified silica sol containing perfluoropolyether-based polysiloxane.

[0033] In step (2) ②, the mass of perfluoropolyether-based polysiloxane accounts for 0.03-0.07% of the mass of modified silica sol. The fluorine content of perfluoropolyether-based polysiloxane (PFPE-HPS) is 35 wt.%, and the manufacturer is Wuhan Kemike Biomedical Technology Co., Ltd.

[0034] Adding perfluoropolyether-based polysiloxane in step (2) ② can reduce the viscosity of the slurry and improve the particle dispersibility. It can completely decompose into inorganic components at high temperature without any residue.

[0035] The preparation method of the modified silica sol in step (2) is as follows: Take 1000g of ordinary silica sol with a SiO2 mass fraction of 30wt.% (containing 300g of SiO2) and stir it at a constant temperature of 50℃. Then add boric acid solution with a mass concentration of 5wt.%. Control the amount of boric acid added so that the concentration of B2O3 in the final modified silica sol is 0.5wt.% (based on the conversion of B2O3 in boric acid: the B2O3 content in boric acid (H3BO3) is 56.45%, and 132.8g of boric acid solution needs to be added, which contains 6.64g of boric acid and can provide 3.75g of B2O3. The boric acid solution is added dropwise over 10min, and the stirring speed is 300r). / min; then add 50g of a mixture of anhydrous ethanol and γ-aminopropyltriethoxysilane (mass ratio of 5:1, i.e., containing 41.6g of anhydrous ethanol and 8.4g of γ-aminopropyltriethoxysilane), with a dropping rate of 1 drop / second (γ-aminopropyltriethoxysilane accounts for 2.8% of the mass of SiO2 in ordinary silica sol, to ensure sufficient modification); finally, stir at 50℃ for 2h, and after cooling, adjust the SiO2 content to 40wt.% by evaporating water to prepare modified silica sol.

[0036] The modified silica sol mentioned in step (2) is a colloidal solution modified with an organosilane coupling agent and containing 0.5 wt.% B2O3. The core component is amorphous SiO2, and the surface contains organic functional groups. The specifications are: SiO2 40 wt.%, B2O3 0.5 wt.% (based on total mass), pH 9.0, particle size 15 nm, viscosity 50 mPa·s (25℃), and good compatibility with PFPE-HPS.

[0037] The drying process described in step (2) ③ involves drying at 60°C for 12 hours.

[0038] In step (2) ③, the thickness of the transition layer is controlled to be 1 mm.

[0039] In step (2), highly spherical mullite particles and fine mullite powder are used as the skeleton material, combined with highly active ρ-Al2O3 and amorphous silicon powder as the reaction raw materials, and nano-yttrium oxide as the whisker catalyst. Modified silica sol can bind particles, supplement SiO2, regulate dispersion and withstand high temperatures. B2O3 forms a low-melting-point liquid phase at 800-1000℃, which lowers the sintering temperature, reduces abnormal grain growth, and increases density. It works synergistically with nano-yttrium oxide to optimize whisker growth, reduce the risk of cracking, and balance the stability of the slurry and the performance of the transition layer. Through the catalytic effect of nano-yttrium oxide and the dispersion regulation of PFPE-HPS, in-situ growth of mullite whiskers can be promoted during sintering at 1300℃, while avoiding the volume instability problem caused by the cristobalite phase transformation.

[0040] The chemical composition of the cordierite powder mentioned in step (3) is Mg2Al4Si5O. 18 The particle size is 500 mesh, and the D50 is 1.8 μm. The surface activation process is as follows: First, the cordierite fine powder is completely immersed in a 10 wt% nitric acid solution for 12 hours at room temperature. This step promotes the reaction of some metal oxides on the surface with nitric acid, initially altering the surface properties. After immersion, the fine powder is removed and rinsed three times with deionized water to remove as much residual nitric acid and reaction products as possible. Then, most of the residual liquid is blown away with a blower, and the powder is placed in a 110°C oven for 3 hours to completely remove moisture. Next, the dried cordierite fine powder is placed in a muffle furnace and calcined at 550°C for 4 hours. High-temperature calcination further optimizes the surface structure of the fine powder, completing the surface activation treatment. This treatment significantly enhances the surface activity of the cordierite fine powder, better meeting the requirements of subsequent processes.

[0041] The nano-lanthanum oxide has a particle size of 35nm and is manufactured by Shandong Mengxi New Materials Co., Ltd.; the nano-boron nitride fiber (BNNF) has a diameter of 160nm and an aspect ratio of 28 and is manufactured by Angxing New Carbon Materials Changzhou Co., Ltd.

[0042] In step (3), the mass of nano-lanthanum oxide accounts for 0.3-0.7% of the mass of cordierite fine powder, and the mass of nano-boron nitride fiber accounts for 0.2-0.4% of the mass of cordierite fine powder.

[0043] In step (3), the mixing time for preparing the premixed powder is 10 min.

[0044] The modified epoxy resin in step (3) is prepared by adding amphiphilic block copolymer P123 to the epoxy resin and stirring for 5 minutes to completely dissolve it, thereby obtaining the modified epoxy resin. The mass of the amphiphilic block copolymer P123 accounts for 0.03-0.07% of the mass of the epoxy resin. The epoxy resin is type E-51, with an epoxy value of 0.51 eq / 100g and a viscosity of 12500 mPa·s. The manufacturer is Hubei Kemaidi Chemical Co., Ltd. The amphiphilic block copolymer P123 (EO... 20 PO 70 EO 20 The molecular weight is 5800. The manufacturer is Zhengzhou Aikem Chemical Co., Ltd. The added amphiphilic block copolymer P123 has its hydrophilic segment adsorbed on the powder surface and its hydrophobic segment forming steric hindrance, which can stabilize the slurry and completely decompose at high temperature without residue.

[0045] In step (3), the mass ratio of cordierite powder to modified epoxy resin is 2:1. Modified epoxy resin is added to the premixed powder and stirred for 20 minutes to prepare a uniformly dispersed prestressed layer slurry.

[0046] In step (3), the thickness of the prestressed layer is controlled to be 1 mm.

[0047] The drying process described in step (3) involves drying at 60°C for 24 hours.

[0048] In step (3), cordierite fine powder serves as the matrix, which imparts excellent high-temperature resistance and chemical stability to the coating. Nano-lanthanum oxide serves as a reinforcing modifier, which improves the coating strength by refining cordierite grains and strengthening grain boundary bonding. Nano-boron nitride fiber serves as an insulating material, which enhances grain boundary bonding through fiber bridging and its layered structure can induce the formation of micropores to improve thermal shock resistance. Modified epoxy resin serves as a binder. Through the grain boundary regulation effect of nano-La2O3 and the dispersion stabilization effect of P123, the density of the cordierite layer can be increased by 5-8% during sintering at 1300℃, while ensuring that the coating has good uniformity and interfacial bonding strength.

[0049] In step (4), the quartz powder has a particle size of 500 mesh, is manufactured by Shijiazhuang Huideli Mineral Products Co., Ltd., and has SiO2 ≥ 99.5%; the borax has a particle size of 600 mesh, and the alumina is α-Al2O3 with a particle size of 1000 mesh.

[0050] The nano-zirconia mentioned in step (4) is ZrO2-3Y; the particle size of zircon sand is 500 mesh, and the chemical composition by mass percentage is as follows: ZrO2 66.5%, SiO2 32.0%, Fe2O3 0.8%, Al2O3 0.5%, TiO2 0.1%, CaO+MgO 0.1%.

[0051] The preparation method of spodumene-modified potassium feldspar in step (4) is as follows: spodumene and potassium feldspar are mixed at a mass ratio of 1:4 and added to a ball mill. The ball-to-material ratio is 2:1 and the rotation speed is 300 r / min. The mixture is wet-milled for 2 hours, passed through a 200-mesh sieve, and then dried at 105℃ for 6 hours. After that, it is placed in a muffle furnace and calcined at 1100℃ for 2 hours. After natural cooling, it is ball-milled again and passed through a 600-mesh sieve to obtain spodumene-modified potassium feldspar.

[0052] The spodumene has a particle size of 800 mesh and its chemical composition by mass percentage is as follows: Li2O 6.2%, SiO2 64.5%, Al2O3 26.0%, MgO 1.0%, CaO 0.3%, Fe2O3 0.8%, and loss on ignition 1.2%.

[0053] The potassium feldspar has a particle size of 800 mesh and its chemical composition by mass percentage is as follows: K2O 10.5%, SiO2 64.0%, Al2O3 18.5%, Na2O 3.0%, CaO 1.2%, Fe2O3 0.8%, and loss on ignition 2.0%.

[0054] In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, and alumina is 3.8-4.2:2.8-3.2:1.8-2.2:0.8-1.2.

[0055] In step (4), the mass of nano-zirconia accounts for 0.5% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; the mass of zircon sand accounts for 0.2-0.4% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; and the mass of polyethylene glycol accounts for 0.05%-0.1% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina. The polyethylene glycol is PEG-6000 produced by Sanda Chemical (Nantong) Co., Ltd. Nano-zirconia primarily enhances the fracture toughness of the glaze layer and reduces the risk of cracking through a "phase transformation toughening" mechanism (the phase transformation of zirconia at temperature changes produces a volume effect). Zircon sand can slowly decompose into ZrO2 and SiO2 during high-temperature sintering, reacting with components such as Al2O3 and Li2O in the glaze layer to generate stable phases such as zircon mullite, adjusting the thermal expansion coefficient of the glaze layer (matching the body and transition layer), while inhibiting excessive flow of the glass phase in the glaze layer, thus improving the high-temperature resistance and insulation stability of the glaze layer.

[0056] In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand, polyethylene glycol, and deionized water is 1:1.2.

[0057] In step (4), the speed of the high-speed dispersant is 3000 r / min and the stirring time is 45 min.

[0058] In step (4), the electrostatic voltage for electrostatic spraying is 60-80kV.

[0059] In step (4), the thickness of the glaze layer on one side is controlled to be 0.50 mm.

[0060] The step drying process described in step (4) is to dry at 40°C for 4 hours, then at 50°C for 8 hours, and finally at 60°C for 12 hours.

[0061] The high-pressure ceramic bushing prepared in step (4) consists of, from the outside to the inside, a glaze layer, a prestress layer, a transition layer, a bushing blank layer, and a glaze layer; an in-situ whisker interface layer is formed in the transition layer, and a bonding network is formed with the bushing blank layer and the prestress layer.

[0062] Compared with the prior art, the present invention has the following advantages:

[0063] (1) The method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestress synergistic reinforcement body according to the present invention, wherein the in-situ whisker interface layer, the prestress layer and the transition layer formed during the sintering process constitute the in-situ whisker interface-prestress synergistic reinforcement body, and the thermal expansion coefficient of the prestress layer is controlled to be less than that of the sleeve blank layer. After the sleeve is sintered, compressive stress is formed in the prestress layer, which offsets the tensile stress when subjected to external impact, thereby achieving a strengthening and toughening effect. In order to reduce the excessive thermal stress mismatch between the prestress layer and the sleeve blank layer, a mullite transition layer is introduced, and the sliding and fluidity of the spherical filler structure are used to alleviate the thermal stress. In particular, an in-situ whisker interface layer is formed in the transition layer. The in-situ whisker interface combines with the outer prestress layer and the inner ceramic layer, playing a whisker bridging role, further improving the combination of the prestress layer and the ceramic layer, enhancing the bonding strength and stress dispersion ability of the two, better playing the effect of the prestress layer, and finally achieving the effect of strengthening the sleeve with the in-situ whisker interface-prestress synergistic reinforcement body.

[0064] (2) The preparation method of the high-pressure ceramic sleeve containing the in-situ whisker interface-prestress synergistic reinforcement body described in this invention involves the in-situ growth of a large number of mullite whiskers in the transition layer during sintering at 1300℃, under the catalysis of nano-yttrium oxide (Y2O3) and the low-temperature liquid phase assistance of B2O3 in modified silica sol, through the diffusion reaction of ρ-Al2O3 and amorphous silicon powder. These whiskers are needle-shaped or fibrous, with an aspect ratio of up to 10-30, a diameter of about 0.5-2μm, and a length extending to 5-20μm. They form a continuous network in the contact area between the transition layer and the sleeve green body, and between the transition layer and the prestress layer, thereby forming an in-situ whisker interface layer. Some whiskers penetrate deep into the micropores and grain gaps on the surface of the green casing, forming a nested bond with the mullite phase in the green body; others interweave between the cordierite particles in the prestressed layer, forming an interlocking nested structure with the cordierite matrix. The whiskers form a three-dimensional interwoven skeleton through overlapping and entanglement, which not only fills the micropores at the interface, but also buffers the thermal expansion differences between different materials through their flexible deformation. This allows the originally separated ceramic layer and prestressed layer to be tightly connected through the whisker network, significantly improving the interfacial bonding strength and anti-delamination ability of the overall structure.

[0065] (3) The preparation method of the high-pressure ceramic sleeve containing the in-situ whisker interface-prestress synergistic reinforcement body described in this invention involves the high-activity ρ-Al2O3 and amorphous silicon powder in the transition layer generating mullite whiskers in-situ under the catalysis of Y2O3 during the sintering process, according to the reaction mechanism of 3Al2O3+2SiO2→3Al2O3·2SiO2, forming a three-dimensional network-like reinforcement structure. This in-situ whisker interface layer forms a gradient transition bond with the sleeve blank layer and the prestress layer, ultimately obtaining a composite sleeve with multi-scale reinforcement.

[0066] (4) The high-voltage porcelain bushing containing in-situ whisker interface-prestressed synergistic reinforcement obtained by the method of the present invention has a tight bond with the matrix through the in-situ generated whisker interface, which plays a toughening role such as bridging and pull-out, significantly improving toughness and crack resistance. At the same time, the prestressed reinforcement can offset the thermal stress generated by the difference in thermal expansion, ensuring structural stability and insulation performance. It is also conducive to large-scale industrial production, can work stably in the harsh environment of high voltage and high current, reduce the risk of accidents, and ensure the safety of the power grid and personnel. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of a high-pressure ceramic bushing containing an in-situ whisker interface-prestressed synergistic reinforcement. In the diagram, 1 is the ceramic bushing; 2 is the transition layer; 3 is the prestressed layer; 4 is the glaze layer; and 5 is the in-situ whisker interface.

[0068] Figure 2 This is a SEM image of the in-situ mullite whisker distribution in the transition layer of Example 1;

[0069] Figure 3 SEM image of in-situ mullite whisker distribution in the transition layer of Example 2;

[0070] Figure 4 This is a SEM image of the in-situ mullite whisker distribution in the transition layer of Example 3. Detailed Implementation

[0071] The present invention will be further described below with reference to embodiments.

[0072] Example 1

[0073] The preparation method of the high-pressure ceramic bushing containing the in-situ whisker interface-prestressed synergistic reinforcement body described in Example 1 consists of the following steps:

[0074] (1) Preparation of casing blank

[0075] Industrial grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass and nano zirconium oxide are mixed evenly and then dry-milled in a planetary ball mill for 10 hours. Triethanolamine is added during ball milling. The resulting mixture is passed through a 200-mesh sieve and then spray-granulated through a 60-mesh sieve. The granulated particles are dried and isostatically pressed to obtain the casing blank.

[0076] (2) Preparation of the transition layer

[0077] ① Mix mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and mix evenly to prepare a mixture;

[0078] ② Add perfluoropolyether-based polysiloxane to the modified silica sol to prepare a modified silica sol containing perfluoropolyether-based polysiloxane;

[0079] ③ Add the mixture to the modified silica sol containing perfluoropolyether-based polysiloxane and stir for 15 minutes. Then add mullite particles and continue mixing for 15 minutes to obtain a transition layer slurry. Spray the transition layer slurry evenly onto the outer wall of the casing blank and dry it to prepare a casing blank containing a transition layer.

[0080] (3) Preparation of prestressed layer

[0081] Cordierite fine powder, nano-lanthanum oxide and nano-boron nitride fibers are mixed to prepare a premixed powder. Modified epoxy resin is added to the premixed powder and stirred evenly to prepare a prestressed layer slurry. The prestressed layer slurry is evenly sprayed onto the outer surface of the casing blank containing the transition layer and dried to prepare a casing blank containing the prestressed layer.

[0082] (4) Quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand and polyethylene glycol are mixed evenly, and then deionized water is added. The mixture is stirred with a high-speed dispersant to form a glaze slurry. The glaze slurry is applied to the outer surface and inner surface of the prestressed casing blank by electrostatic spraying. The casing blank with a glaze layer is prepared by step drying process.

[0083] (5) Sintering: The glazed sleeve blank is placed in a high-temperature furnace and heated to 1300℃ at a rate of 5℃ / min. It is then held for 2 hours for sintering to prepare a high-pressure ceramic sleeve containing in-situ whisker interface-prestress synergistic reinforcement.

[0084] in:

[0085] The casing blank in step (1) is composed of the following raw materials: industrial-grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass, nano-zirconia, and triethanolamine. The mass ratio of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay is 59.9: 34.9: 3.1: 2.1. The mass of high-purity modified water glass accounts for 0.6% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of nano-zirconia accounts for 0.5% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of triethanolamine accounts for 0.1% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay.

[0086] In step (1), the particle size of potassium feldspar powder is 200 mesh.

[0087] The industrial-grade bauxite mentioned in step (1) has the following chemical composition by mass percentage: Al2O3 78.3%, SiO2 12.1%, Fe2O3 2.0%, TiO2 2.4%, CaO 0.3%, MgO 0.2%, K2O 0.2%, Na2O 0.1%, and loss on ignition 4.4%.

[0088] The calcined kaolin described in step (1) has the following chemical composition by mass percentage: Al2O3 44.5%, SiO2 52.6%, Fe2O3 0.4%, TiO2 0.8%, CaO 0.2%, MgO 0.1%, K2O 0.2%, Na2O 0.1%, and loss on ignition 1.1%.

[0089] In step (1), the high-purity modified water glass is KN-40A produced by Foshan Kening New Material Technology Co., Ltd.

[0090] In step (1), alumina balls are used as the grinding medium during ball milling, and the ball-to-material ratio is 3:1.

[0091] In step (1), the drying temperature is 80℃, the drying time is 12h, the isostatic pressing pressure is 120MPa, and the holding time is 3min.

[0092] In step (1), industrial-grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, and high-purity modified water glass are put into a ball mill. The ball mill is turned on for initial mixing, and the mixing time is 10 minutes to ensure that the high-purity modified water glass is evenly attached to the surface of the main raw materials. Then, nano-zirconia toughening agent is added, and mixing continues for 10 minutes to ensure that nano-zirconia is initially dispersed in the material. Then, triethanolamine grinding aid is added, and then ball milling is performed. The planetary ball mill is set to dry ball milling mode, and the ball milling time is 10 hours to ensure that the material is fully ground and mixed. After the ball milling is completed, the mixture is taken out and passed through a 200-mesh sieve to remove any large particles that may exist and to ensure the fineness of the material. Then, the sieved material is sent to a spray granulation equipment for granulation. After granulation, it is passed through a 60-mesh sieve.

[0093] In step (2), the mass ratio of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder is 3.0: 3.0: 2.0: 2.0; the mass of nano-yttrium oxide accounts for 0.8% of the total mass of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder.

[0094] The mullite particles mentioned in step (2) are spherical ceramic sand produced by Hunan Jiashun Huaxin Materials Co., Ltd., with a sphericity ≥95% and a particle size of 100 mesh; the mullite fine powder is produced by Luoyang Benteng Refractory Materials Co., Ltd., with a particle size of 1000 mesh, D 50 =12μm; ρ-Al2O3 has a particle size of 1000 mesh and a specific surface area of ​​250m². 2 / g; amorphous silicon powder is α-Si, particle size is 1000 mesh, D 90 =2μm, manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd.; the particle size of nano-yttrium oxide is 30nm.

[0095] In step (2)①, first mix the mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and stir for 10 minutes to make it evenly dispersed in the fine powder system.

[0096] Step (2) ② Add perfluoropolyether-based polysiloxane to the modified silica sol and stir for 5 minutes to completely dissolve it, thus preparing a modified silica sol containing perfluoropolyether-based polysiloxane.

[0097] In step (2) ②, the mass of perfluoropolyether-based polysiloxane accounts for 0.05% of the mass of modified silica sol. The fluorine content of perfluoropolyether-based polysiloxane (PFPE-HPS) is 35 wt.%, and the manufacturer is Wuhan Kemike Biomedical Technology Co., Ltd.

[0098] The modified silica sol in step (2) is prepared as follows: 1000g of ordinary silica sol with a SiO2 mass fraction of 30wt.% (containing 300g of SiO2) is stirred at a constant temperature of 50℃, and then boric acid solution is added. The mass concentration of the boric acid solution is 5wt.%. The amount of boric acid added is controlled so that the concentration of B2O3 in the final modified silica sol is 0.5wt.% (based on the conversion of B2O3 in boric acid: the B2O3 content in boric acid (H3BO3) is 56.45%, and 132.8g of boric acid solution needs to be added, which contains 6.64g of boric acid and can provide 3.75g of B2O3). The boric acid solution is added dropwise over 10min, and the stirring speed is 300r. / min; then add 50g of a mixture of anhydrous ethanol and γ-aminopropyltriethoxysilane (mass ratio of 5:1, i.e., containing 41.6g of anhydrous ethanol and 8.4g of γ-aminopropyltriethoxysilane), with a dropping rate of 1 drop / second (γ-aminopropyltriethoxysilane accounts for 2.8% of the mass of SiO2 in ordinary silica sol, to ensure sufficient modification); finally, stir at 50℃ for 2h, and after cooling, adjust the SiO2 content to 40wt.% by evaporating water to prepare modified silica sol.

[0099] The modified silica sol mentioned in step (2) is a colloidal solution modified with an organosilane coupling agent and containing 0.5 wt.% B2O3. The core component is amorphous SiO2, and the surface contains organic functional groups. The specifications are: SiO2 40 wt.%, B2O3 0.5 wt.% (based on total mass), pH 9.0, particle size 15 nm, viscosity 50 mPa·s (25℃), and good compatibility with PFPE-HPS.

[0100] The drying process described in step (2) ③ involves drying at 60°C for 12 hours.

[0101] In step (2) ③, the thickness of the transition layer is controlled to be 1 mm.

[0102] The chemical composition of the cordierite powder mentioned in step (3) is Mg2Al4Si5O. 18The particle size is 500 mesh, and the D50 is 1.8 μm. The surface activation process is as follows: First, the cordierite fine powder is completely immersed in a 10 wt% nitric acid solution for 12 hours at room temperature. This step promotes the reaction of some metal oxides on the surface with nitric acid, initially altering the surface properties. After immersion, the fine powder is removed and rinsed three times with deionized water to remove as much residual nitric acid and reaction products as possible. Then, most of the residual liquid is blown away with a blower, and the powder is placed in a 110°C oven for 3 hours to completely remove moisture. Next, the dried cordierite fine powder is placed in a muffle furnace and calcined at 550°C for 4 hours. High-temperature calcination further optimizes the surface structure of the fine powder, completing the surface activation treatment. This treatment significantly enhances the surface activity of the cordierite fine powder, better meeting the requirements of subsequent processes.

[0103] The nano-lanthanum oxide has a particle size of 35nm and is manufactured by Shandong Mengxi New Materials Co., Ltd.; the nano-boron nitride fiber (BNNF) has a diameter of 160nm and an aspect ratio of 28 and is manufactured by Angxing New Carbon Materials Changzhou Co., Ltd.

[0104] In step (3), the mass of nano-lanthanum oxide accounts for 0.5% of the mass of cordierite fine powder, and the mass of nano-boron nitride fiber accounts for 0.3% of the mass of cordierite fine powder.

[0105] In step (3), the mixing time for preparing the premixed powder is 10 min.

[0106] The modified epoxy resin in step (3) is prepared by adding amphiphilic block copolymer P123 to the epoxy resin and stirring for 5 minutes to completely dissolve it, thereby obtaining the modified epoxy resin. The mass of the amphiphilic block copolymer P123 accounts for 0.05% of the mass of the epoxy resin. The epoxy resin is type E-51, with an epoxy value of 0.51 eq / 100g and a viscosity of 12500 mPa·s. The manufacturer is Hubei Kemaidi Chemical Co., Ltd. The amphiphilic block copolymer P123 (EO... 20 PO 70 EO 20 The molecular weight is 5800. The manufacturer is Zhengzhou Aikem Chemical Co., Ltd. The added amphiphilic block copolymer P123 has its hydrophilic segment adsorbed on the powder surface and its hydrophobic segment forming steric hindrance, which can stabilize the slurry and completely decompose at high temperature without residue.

[0107] In step (3), the mass ratio of cordierite powder to modified epoxy resin is 2:1. Modified epoxy resin is added to the premixed powder and stirred for 20 minutes to prepare a uniformly dispersed prestressed layer slurry.

[0108] In step (3), the thickness of the prestressed layer is controlled to be 1 mm.

[0109] The drying process described in step (3) involves drying at 60°C for 24 hours.

[0110] In step (4), the quartz powder has a particle size of 500 mesh, is manufactured by Shijiazhuang Huideli Mineral Products Co., Ltd., and has SiO2 ≥ 99.5%; the borax has a particle size of 600 mesh, and the alumina is α-Al2O3 with a particle size of 1000 mesh.

[0111] The nano-zirconia mentioned in step (4) is ZrO2-3Y; the particle size of zircon sand is 500 mesh, and the chemical composition by mass percentage is as follows: ZrO2 66.5%, SiO2 32.0%, Fe2O3 0.8%, Al2O3 0.5%, TiO2 0.1%, CaO+MgO 0.1%.

[0112] The preparation method of spodumene-modified potassium feldspar in step (4) is as follows: spodumene and potassium feldspar are mixed at a mass ratio of 1:4 and added to a ball mill. The ball-to-material ratio is 2:1 and the rotation speed is 300 r / min. The mixture is wet-milled for 2 hours, passed through a 200-mesh sieve, and then dried at 105℃ for 6 hours. After that, it is placed in a muffle furnace and calcined at 1100℃ for 2 hours. After natural cooling, it is ball-milled again and passed through a 600-mesh sieve to obtain spodumene-modified potassium feldspar.

[0113] The spodumene has a particle size of 800 mesh and its chemical composition by mass percentage is as follows: Li2O 6.2%, SiO2 64.5%, Al2O3 26.0%, MgO 1.0%, CaO 0.3%, Fe2O3 0.8%, and loss on ignition 1.2%.

[0114] The potassium feldspar has a particle size of 800 mesh and its chemical composition by mass percentage is as follows: K2O 10.5%, SiO2 64.0%, Al2O3 18.5%, Na2O 3.0%, CaO 1.2%, Fe2O3 0.8%, and loss on ignition 2.0%.

[0115] In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, and alumina is 4.0:3.0:2.0:1.0.

[0116] In step (4), the mass of nano-zirconia accounts for 0.5% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; the mass of zircon sand accounts for 0.3% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; and the mass of polyethylene glycol accounts for 0.07% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina. The polyethylene glycol is PEG-6000 produced by Sanda Chemical (Nantong) Co., Ltd.

[0117] In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand, polyethylene glycol, and deionized water is 1:1.2.

[0118] In step (4), the speed of the high-speed dispersant is 3000 r / min and the stirring time is 45 min.

[0119] In step (4), the electrostatic voltage for electrostatic spraying is 70kV.

[0120] In step (4), the thickness of the glaze layer on one side is controlled to be 0.50 mm.

[0121] The step drying process described in step (4) is to dry at 40°C for 4 hours, then at 50°C for 8 hours, and finally at 60°C for 12 hours.

[0122] The high-pressure ceramic bushing prepared in step (4) with an in-situ whisker interface-prestressed synergistic reinforcement consists of, from the outside to the inside, a glaze layer, a prestressed layer, a transition layer, a bushing blank layer, and another glaze layer. An in-situ whisker interface layer is formed in the transition layer, which forms a bonding network with the bushing blank layer and the prestressed layer. The high-pressure ceramic bushing prepared in Example 1 has a fracture toughness of 9.8 MPa·m measured using the single-sided notched beam method. 1 / 2 Its flexural strength is 305 MPa.

[0123] Figure 1 This is a schematic diagram of a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement. The diagram clearly shows the layered structure of the sleeve from the outside to the inside, namely the glaze layer, the prestressed layer, the transition layer, the sleeve blank layer, and the glaze layer. It is clear that the "in-situ whisker interface" is formed in the transition layer and forms a combined network with the sleeve blank layer and the prestressed layer. The diagram intuitively demonstrates the synergistic reinforcement structure of each layer, which helps to understand the overall architecture and working principle of the invention.

[0124] Figure 2 This is a SEM image (5.0 kV, 10.1 mm × 10.0 k SE, 5.00 μm scale bar) of in-situ mullite whiskers in the transition layer of Example 1. Under this SEM image, numerous needle-like and fibrous mullite whiskers are visible distributed in the transition layer region. The whiskers interweave and interpenetrate, some penetrating deep into the micropores and intergranular spaces of the sleeve blank, and some embedded between the prestressed layer particles, exhibiting a radial and interlaced microscopic distribution. Measurements using the scale bar show that the whisker diameter is approximately 0.5-1.2 μm, the length is approximately 8-18 μm, and the aspect ratio is approximately 15-30, consistent with the description in the invention that "the aspect ratio can reach 10-30, the diameter is approximately 0.2-1.5 μm, and the length extends to 5-20 μm."

[0125] Example 2

[0126] The preparation method of the high-pressure ceramic sleeve containing the in-situ whisker interface-prestressed synergistic reinforcement body described in Example 2 consists of the following steps:

[0127] (1) Preparation of casing blank

[0128] Industrial grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass and nano zirconium oxide are mixed evenly and then dry-milled in a planetary ball mill for 10 hours. Triethanolamine is added during ball milling. The resulting mixture is passed through a 200-mesh sieve and then spray-granulated through a 60-mesh sieve. The granulated particles are dried and isostatically pressed to obtain the casing blank.

[0129] (2) Preparation of the transition layer

[0130] ① Mix mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and mix evenly to prepare a mixture;

[0131] ② Add perfluoropolyether-based polysiloxane to the modified silica sol to prepare a modified silica sol containing perfluoropolyether-based polysiloxane;

[0132] ③ Add the mixture to the modified silica sol containing perfluoropolyether-based polysiloxane and stir for 15 minutes. Then add mullite particles and continue mixing for 15 minutes to obtain a transition layer slurry. Spray the transition layer slurry evenly onto the outer wall of the casing blank and dry it to prepare a casing blank containing a transition layer.

[0133] (3) Preparation of prestressed layer

[0134] Cordierite fine powder, nano-lanthanum oxide and nano-boron nitride fibers are mixed to prepare a premixed powder. Modified epoxy resin is added to the premixed powder and stirred evenly to prepare a prestressed layer slurry. The prestressed layer slurry is evenly sprayed onto the outer surface of the casing blank containing the transition layer and dried to prepare a casing blank containing the prestressed layer.

[0135] (4) Quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand and polyethylene glycol are mixed evenly, and then deionized water is added. The mixture is stirred with a high-speed dispersant to form a glaze slurry. The glaze slurry is applied to the outer surface and inner surface of the prestressed casing blank by electrostatic spraying. The casing blank with a glaze layer is prepared by step drying process.

[0136] (5) Sintering: The glazed sleeve blank is placed in a high-temperature furnace and heated to 1300℃ at a rate of 5℃ / min. It is then held for 2 hours for sintering to prepare a high-pressure ceramic sleeve containing in-situ whisker interface-prestress synergistic reinforcement.

[0137] in:

[0138] The casing blank in step (1) is composed of the following raw materials: industrial-grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass, nano-zirconia, and triethanolamine. The mass ratio of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay is 59.9: 34.9: 3.1: 2.1. The mass of high-purity modified water glass accounts for 0.6% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of nano-zirconia accounts for 0.5% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of triethanolamine accounts for 0.1% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay.

[0139] In step (1), the particle size of potassium feldspar powder is 200 mesh.

[0140] The industrial-grade bauxite mentioned in step (1) has the following chemical composition by mass percentage: Al2O3 78.3%, SiO2 12.1%, Fe2O3 2.0%, TiO2 2.4%, CaO 0.3%, MgO 0.2%, K2O 0.2%, Na2O 0.1%, and loss on ignition 4.4%.

[0141] The calcined kaolin described in step (1) has the following chemical composition by mass percentage: Al2O3 44.5%, SiO2 52.6%, Fe2O3 0.4%, TiO2 0.8%, CaO 0.2%, MgO 0.1%, K2O 0.2%, Na2O 0.1%, and loss on ignition 1.1%.

[0142] In step (1), the high-purity modified water glass is KN-40A produced by Foshan Kening New Material Technology Co., Ltd.

[0143] In step (1), alumina balls are used as the grinding medium during ball milling, and the ball-to-material ratio is 3:1.

[0144] In step (1), the drying temperature is 80℃, the drying time is 12h, the isostatic pressing pressure is 120MPa, and the holding time is 3min.

[0145] In step (1), industrial-grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, and high-purity modified water glass are put into a ball mill. The ball mill is turned on for initial mixing, and the mixing time is 10 minutes to ensure that the high-purity modified water glass is evenly attached to the surface of the main raw materials. Then, nano-zirconia toughening agent is added, and mixing continues for 10 minutes to ensure that nano-zirconia is initially dispersed in the material. Then, triethanolamine grinding aid is added, and then ball milling is performed. The planetary ball mill is set to dry ball milling mode, and the ball milling time is 10 hours to ensure that the material is fully ground and mixed. After the ball milling is completed, the mixture is taken out and passed through a 200-mesh sieve to remove any large particles that may exist and to ensure the fineness of the material. Then, the sieved material is sent to a spray granulation equipment for granulation. After granulation, it is passed through a 60-mesh sieve.

[0146] In step (2), the mass ratio of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder is 2.8:3.2:1.8:2.2; the mass of nano-yttrium oxide accounts for 0.8% of the total mass of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder.

[0147] The mullite particles mentioned in step (2) are spherical ceramic sand produced by Hunan Jiashun Huaxin Materials Co., Ltd., with a sphericity ≥95% and a particle size of 100 mesh; the mullite fine powder is produced by Luoyang Benteng Refractory Materials Co., Ltd., with a particle size of 1000 mesh, D 50 =12μm; ρ-Al2O3 has a particle size of 1000 mesh and a specific surface area of ​​250m². 2 / g; amorphous silicon powder is α-Si, particle size is 1000 mesh, D 90 =2μm, manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd.; the particle size of nano-yttrium oxide is 30nm.

[0148] In step (2)①, first mix the mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and stir for 10 minutes to make it evenly dispersed in the fine powder system.

[0149] Step (2) ② Add perfluoropolyether-based polysiloxane to the modified silica sol and stir for 5 minutes to completely dissolve it, thus preparing a modified silica sol containing perfluoropolyether-based polysiloxane.

[0150] In step (2) ②, the mass of perfluoropolyether-based polysiloxane accounts for 0.03% of the mass of modified silica sol. The fluorine content of perfluoropolyether-based polysiloxane (PFPE-HPS) is 35 wt.%, and the manufacturer is Wuhan Kemike Biomedical Technology Co., Ltd.

[0151] Adding perfluoropolyether-based polysiloxane in step (2) ② can reduce the viscosity of the slurry and improve the particle dispersibility. It can completely decompose into inorganic components at high temperature without any residue.

[0152] The modified silica sol in step (2) is prepared as follows: 1000g of ordinary silica sol with a SiO2 mass fraction of 30wt.% (containing 300g of SiO2) is stirred at a constant temperature of 50℃, and then boric acid solution is added. The mass concentration of the boric acid solution is 5wt.%. The amount of boric acid added is controlled so that the concentration of B2O3 in the final modified silica sol is 0.5wt.% (based on the conversion of B2O3 in boric acid: the B2O3 content in boric acid (H3BO3) is 56.45%, and 132.8g of boric acid solution needs to be added, which contains 6.64g of boric acid and can provide 3.75g of B2O3). The boric acid solution is added dropwise over 10min, and the stirring speed is 300r. / min; then add 50g of a mixture of anhydrous ethanol and γ-aminopropyltriethoxysilane (mass ratio of 5:1, i.e., containing 41.6g of anhydrous ethanol and 8.4g of γ-aminopropyltriethoxysilane), with a dropping rate of 1 drop / second (γ-aminopropyltriethoxysilane accounts for 2.8% of the mass of SiO2 in ordinary silica sol, to ensure sufficient modification); finally, stir at 50℃ for 2h, and after cooling, adjust the SiO2 content to 40wt.% by evaporating water to prepare modified silica sol.

[0153] The modified silica sol described in step (2) is a colloidal solution modified with an organosilane coupling agent and containing 0.5 wt.% B2O3. Its core component is amorphous SiO2, and its surface contains organic functional groups. The specifications are: SiO2 40 wt.%, B2O3 0.5 wt.% (based on total mass), pH 9.0, particle size 15 nm, viscosity 50 mPa·s (25℃), and good compatibility with PFPE-HPS. The drying described in step (2) ③ is performed at 60℃ for 12 hours.

[0154] In step (2) ③, the thickness of the transition layer is controlled to be 1 mm.

[0155] The chemical composition of the cordierite powder mentioned in step (3) is Mg2Al4Si5O. 18 The particle size is 500 mesh, and the D50 is 1.8 μm. The surface activation process is as follows: First, the cordierite fine powder is completely immersed in a 10 wt% nitric acid solution for 12 hours at room temperature. This step promotes the reaction of some metal oxides on the surface with nitric acid, initially altering the surface properties. After immersion, the fine powder is removed and rinsed three times with deionized water to remove as much residual nitric acid and reaction products as possible. Then, most of the residual liquid is blown away with a blower, and the powder is placed in a 110°C oven for 3 hours to completely remove moisture. Next, the dried cordierite fine powder is placed in a muffle furnace and calcined at 550°C for 4 hours. High-temperature calcination further optimizes the surface structure of the fine powder, completing the surface activation treatment. This treatment significantly enhances the surface activity of the cordierite fine powder, better meeting the requirements of subsequent processes.

[0156] The nano-lanthanum oxide has a particle size of 35nm and is manufactured by Shandong Mengxi New Materials Co., Ltd.; the nano-boron nitride fiber (BNNF) has a diameter of 160nm and an aspect ratio of 28 and is manufactured by Angxing New Carbon Materials Changzhou Co., Ltd.

[0157] In step (3), the mass of nano-lanthanum oxide accounts for 0.3% of the mass of cordierite fine powder, and the mass of nano-boron nitride fiber accounts for 0.4% of the mass of cordierite fine powder.

[0158] In step (3), the mixing time for preparing the premixed powder is 10 min.

[0159] The modified epoxy resin in step (3) is prepared by adding amphiphilic block copolymer P123 to the epoxy resin and stirring for 5 minutes to completely dissolve it, thereby obtaining the modified epoxy resin. The mass of the amphiphilic block copolymer P123 accounts for 0.03% of the mass of the epoxy resin. The epoxy resin is type E-51, with an epoxy value of 0.51 eq / 100g and a viscosity of 12500 mPa·s. The manufacturer is Hubei Kemaidi Chemical Co., Ltd. The amphiphilic block copolymer P123 (EO... 20 PO 70 EO 20 The molecular weight is 5800. The manufacturer is Zhengzhou Aikem Chemical Co., Ltd. The added amphiphilic block copolymer P123 has its hydrophilic segment adsorbed on the powder surface and its hydrophobic segment forming steric hindrance, which can stabilize the slurry and completely decompose at high temperature without residue.

[0160] In step (3), the mass ratio of cordierite powder to modified epoxy resin is 2:1. Modified epoxy resin is added to the premixed powder and stirred for 20 minutes to prepare a uniformly dispersed prestressed layer slurry.

[0161] In step (3), the thickness of the prestressed layer is controlled to be 1 mm.

[0162] The drying process described in step (3) involves drying at 60°C for 24 hours.

[0163] In step (4), the quartz powder has a particle size of 500 mesh, is manufactured by Shijiazhuang Huideli Mineral Products Co., Ltd., and has SiO2 ≥ 99.5%; the borax has a particle size of 600 mesh, and the alumina is α-Al2O3 with a particle size of 1000 mesh.

[0164] The nano-zirconia mentioned in step (4) is ZrO2-3Y; the particle size of zircon sand is 500 mesh, and the chemical composition by mass percentage is as follows: ZrO2 66.5%, SiO2 32.0%, Fe2O3 0.8%, Al2O3 0.5%, TiO2 0.1%, CaO+MgO 0.1%.

[0165] The preparation method of spodumene-modified potassium feldspar in step (4) is as follows: spodumene and potassium feldspar are mixed at a mass ratio of 1:4 and added to a ball mill. The ball-to-material ratio is 2:1 and the rotation speed is 300 r / min. The mixture is wet-milled for 2 hours, passed through a 200-mesh sieve, and then dried at 105℃ for 6 hours. After that, it is placed in a muffle furnace and calcined at 1100℃ for 2 hours. After natural cooling, it is ball-milled again and passed through a 600-mesh sieve to obtain spodumene-modified potassium feldspar.

[0166] The spodumene has a particle size of 800 mesh and its chemical composition by mass percentage is as follows: Li2O 6.2%, SiO2 64.5%, Al2O3 26.0%, MgO 1.0%, CaO 0.3%, Fe2O3 0.8%, and loss on ignition 1.2%.

[0167] The potassium feldspar has a particle size of 800 mesh and its chemical composition by mass percentage is as follows: K2O 10.5%, SiO2 64.0%, Al2O3 18.5%, Na2O 3.0%, CaO 1.2%, Fe2O3 0.8%, and loss on ignition 2.0%.

[0168] In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, and alumina is 3.8:3.2:1.8:0.8.

[0169] In step (4), the mass of nano-zirconia accounts for 0.5% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; the mass of zircon sand accounts for 0.4% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; and the mass of polyethylene glycol accounts for 0.05% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina. The polyethylene glycol is PEG-6000 produced by Sanda Chemical (Nantong) Co., Ltd.

[0170] In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand, polyethylene glycol, and deionized water is 1:1.2.

[0171] In step (4), the speed of the high-speed dispersant is 3000 r / min and the stirring time is 45 min.

[0172] In step (4), the electrostatic voltage for electrostatic spraying is 60kV.

[0173] In step (4), the thickness of the glaze layer on one side is controlled to be 0.50 mm.

[0174] The step drying process described in step (4) is to dry at 40°C for 4 hours, then at 50°C for 8 hours, and finally at 60°C for 12 hours.

[0175] The high-pressure ceramic bushing prepared in step (4) with an in-situ whisker interface-prestressed synergistic reinforcement consists of, from the outside to the inside, a glaze layer, a prestressed layer, a transition layer, a bushing blank layer, and another glaze layer. An in-situ whisker interface layer is formed in the transition layer, which forms a bonding network with the bushing blank layer and the prestressed layer. The high-pressure ceramic bushing prepared in Example 2 has a fracture toughness of 9.1 MPa·m measured using the single-sided notched beam method. 1 / 2 Its flexural strength is 280 MPa.

[0176] Figure 3 This is a SEM image (5.0 kV, 10.3 mm × 10.0 k SE, 5.00 μm scale) of in-situ mullite whiskers in the transition layer of Example 2. The image shows the microstructure of the mullite whiskers in the transition layer of Example 2. The whisker distribution density in the image is slightly lower than in Figure 2 (Example 1), reflecting the changes in whisker growth caused by differences in process parameters (fine-tuning of raw material ratios, etc.). However, it is evident that a large number of needle-like and fibrous mullite whiskers are distributed in the transition layer region. The whiskers interweave and penetrate each other, some penetrating deep into the micropores and grain gaps of the sleeve blank, and some embedding between the prestressed layer particles, exhibiting a radial and interlaced microstructure. Measurements using the scale show that the whisker diameter is approximately 0.6-1.5 μm, the length is approximately 6-15 μm, and the aspect ratio is approximately 10-25, which conforms to the range of "aspect ratio 10-30, diameter 0.5-2 μm, length 5-20 μm" in the invention, verifying the effective generation of in-situ whiskers.

[0177] Example 3

[0178] The preparation method of the high-pressure ceramic sleeve containing the in-situ whisker interface-prestressed synergistic reinforcement body described in Example 3 consists of the following steps:

[0179] (1) Preparation of casing blank

[0180] Industrial grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass and nano zirconium oxide are mixed evenly and then dry-milled in a planetary ball mill for 10 hours. Triethanolamine is added during ball milling. The resulting mixture is passed through a 200-mesh sieve and then spray-granulated through a 60-mesh sieve. The granulated particles are dried and isostatically pressed to obtain the casing blank.

[0181] (2) Preparation of the transition layer

[0182] ① Mix mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and mix evenly to prepare a mixture;

[0183] ② Add perfluoropolyether-based polysiloxane to the modified silica sol to prepare a modified silica sol containing perfluoropolyether-based polysiloxane;

[0184] ③ Add the mixture to the modified silica sol containing perfluoropolyether-based polysiloxane and stir for 15 minutes. Then add mullite particles and continue mixing for 15 minutes to obtain a transition layer slurry. Spray the transition layer slurry evenly onto the outer wall of the casing blank and dry it to prepare a casing blank containing a transition layer.

[0185] (3) Preparation of prestressed layer

[0186] Cordierite fine powder, nano-lanthanum oxide and nano-boron nitride fibers are mixed to prepare a premixed powder. Modified epoxy resin is added to the premixed powder and stirred evenly to prepare a prestressed layer slurry. The prestressed layer slurry is evenly sprayed onto the outer surface of the casing blank containing the transition layer and dried to prepare a casing blank containing the prestressed layer.

[0187] (4) Quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand and polyethylene glycol are mixed evenly, and then deionized water is added. The mixture is stirred with a high-speed dispersant to form a glaze slurry. The glaze slurry is applied to the outer surface and inner surface of the prestressed casing blank by electrostatic spraying. The casing blank with a glaze layer is prepared by step drying process.

[0188] (5) Sintering: The glazed sleeve blank is placed in a high-temperature furnace and heated to 1300℃ at a rate of 5℃ / min. It is then held for 2 hours for sintering to prepare a high-pressure ceramic sleeve containing in-situ whisker interface-prestress synergistic reinforcement.

[0189] in:

[0190] The casing blank in step (1) is composed of the following raw materials: industrial-grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass, nano-zirconia, and triethanolamine. The mass ratio of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay is 59.9: 34.9: 3.1: 2.1. The mass of high-purity modified water glass accounts for 0.6% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of nano-zirconia accounts for 0.5% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of triethanolamine accounts for 0.1% of the total mass of industrial-grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay.

[0191] In step (1), the particle size of potassium feldspar powder is 200 mesh.

[0192] The industrial-grade bauxite mentioned in step (1) has the following chemical composition by mass percentage: Al2O3 78.3%, SiO2 12.1%, Fe2O3 2.0%, TiO2 2.4%, CaO 0.3%, MgO 0.2%, K2O 0.2%, Na2O 0.1%, and loss on ignition 4.4%.

[0193] The calcined kaolin described in step (1) has the following chemical composition by mass percentage: Al2O3 44.5%, SiO2 52.6%, Fe2O3 0.4%, TiO2 0.8%, CaO 0.2%, MgO 0.1%, K2O 0.2%, Na2O 0.1%, and loss on ignition 1.1%.

[0194] In step (1), the high-purity modified water glass is KN-40A produced by Foshan Kening New Material Technology Co., Ltd.

[0195] In step (1), alumina balls are used as the grinding medium during ball milling, and the ball-to-material ratio is 3:1.

[0196] In step (1), the drying temperature is 80℃, the drying time is 12h, the isostatic pressing pressure is 120MPa, and the holding time is 3min.

[0197] In step (1), industrial-grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, and high-purity modified water glass are put into a ball mill. The ball mill is turned on for initial mixing, and the mixing time is 10 minutes to ensure that the high-purity modified water glass is evenly attached to the surface of the main raw materials. Then, nano-zirconia toughening agent is added, and mixing continues for 10 minutes to ensure that nano-zirconia is initially dispersed in the material. Then, triethanolamine grinding aid is added, and then ball milling is performed. The planetary ball mill is set to dry ball milling mode, and the ball milling time is 10 hours to ensure that the material is fully ground and mixed. After the ball milling is completed, the mixture is taken out and passed through a 200-mesh sieve to remove any large particles that may exist and to ensure the fineness of the material. Then, the sieved material is sent to a spray granulation equipment for granulation. After granulation, it is passed through a 60-mesh sieve.

[0198] In step (2), the mass ratio of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder is 3.2: 2.8: 2.2: 1.8; the mass of nano-yttrium oxide accounts for 0.8% of the total mass of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder.

[0199] The mullite particles mentioned in step (2) are spherical ceramic sand produced by Hunan Jiashun Huaxin Materials Co., Ltd., with a sphericity ≥95% and a particle size of 100 mesh; the mullite fine powder is produced by Luoyang Benteng Refractory Materials Co., Ltd., with a particle size of 1000 mesh, D 50=12μm; ρ-Al2O3 has a particle size of 1000 mesh and a specific surface area of ​​250m². 2 / g; amorphous silicon powder is α-Si, particle size is 1000 mesh, D 90 =2μm, manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd.; the particle size of nano-yttrium oxide is 30nm.

[0200] In step (2)①, first mix the mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and stir for 10 minutes to make it evenly dispersed in the fine powder system.

[0201] Step (2) ② Add perfluoropolyether-based polysiloxane to the modified silica sol and stir for 5 minutes to completely dissolve it, thus preparing a modified silica sol containing perfluoropolyether-based polysiloxane.

[0202] In step (2) ②, the mass of perfluoropolyether-based polysiloxane accounts for 0.07% of the mass of modified silica sol. The fluorine content of perfluoropolyether-based polysiloxane (PFPE-HPS) is 35 wt.%, and the manufacturer is Wuhan Kemike Biomedical Technology Co., Ltd.

[0203] Adding perfluoropolyether-based polysiloxane in step (2) ② can reduce the viscosity of the slurry and improve the particle dispersibility. It can completely decompose into inorganic components at high temperature without any residue.

[0204] The modified silica sol in step (2) is prepared as follows: 1000g of ordinary silica sol with a SiO2 mass fraction of 30wt.% (containing 300g of SiO2) is stirred at a constant temperature of 50℃, and then boric acid solution is added. The mass concentration of the boric acid solution is 5wt.%. The amount of boric acid added is controlled so that the concentration of B2O3 in the final modified silica sol is 0.5wt.% (based on the conversion of B2O3 in boric acid: the B2O3 content in boric acid (H3BO3) is 56.45%, and 132.8g of boric acid solution needs to be added, which contains 6.64g of boric acid and can provide 3.75g of B2O3). The boric acid solution is added dropwise over 10min, and the stirring speed is 300r. / min; then add 50g of a mixture of anhydrous ethanol and γ-aminopropyltriethoxysilane (mass ratio of 5:1, i.e., containing 41.6g of anhydrous ethanol and 8.4g of γ-aminopropyltriethoxysilane), with a dropping rate of 1 drop / second (γ-aminopropyltriethoxysilane accounts for 2.8% of the mass of SiO2 in ordinary silica sol, to ensure sufficient modification); finally, stir at 50℃ for 2h, and after cooling, adjust the SiO2 content to 40wt.% by evaporating water to prepare modified silica sol.

[0205] The modified silica sol mentioned in step (2) is a colloidal solution modified with an organosilane coupling agent and containing 0.5 wt.% B2O3. The core component is amorphous SiO2, and the surface contains organic functional groups. The specifications are: SiO2 40 wt.%, B2O3 0.5 wt.% (based on total mass), pH 9.0, particle size 15 nm, viscosity 50 mPa·s (25℃), and good compatibility with PFPE-HPS.

[0206] The drying process described in step (2) ③ involves drying at 60°C for 12 hours.

[0207] In step (2) ③, the thickness of the transition layer is controlled to be 1 mm.

[0208] The chemical composition of the cordierite powder mentioned in step (3) is Mg2Al4Si5O. 18 The particle size is 500 mesh, and the D50 is 1.8 μm. The surface activation process is as follows: First, the cordierite fine powder is completely immersed in a 10 wt% nitric acid solution for 12 hours at room temperature. This step promotes the reaction of some metal oxides on the surface with nitric acid, initially altering the surface properties. After immersion, the fine powder is removed and rinsed three times with deionized water to remove as much residual nitric acid and reaction products as possible. Then, most of the residual liquid is blown away with a blower, and the powder is placed in a 110°C oven for 3 hours to completely remove moisture. Next, the dried cordierite fine powder is placed in a muffle furnace and calcined at 550°C for 4 hours. High-temperature calcination further optimizes the surface structure of the fine powder, completing the surface activation treatment. This treatment significantly enhances the surface activity of the cordierite fine powder, better meeting the requirements of subsequent processes.

[0209] The nano-lanthanum oxide has a particle size of 35nm and is manufactured by Shandong Mengxi New Materials Co., Ltd.; the nano-boron nitride fiber (BNNF) has a diameter of 160nm and an aspect ratio of 28 and is manufactured by Angxing New Carbon Materials Changzhou Co., Ltd.

[0210] In step (3), the mass of nano-lanthanum oxide accounts for 0.7% of the mass of cordierite fine powder, and the mass of nano-boron nitride fiber accounts for 0.2% of the mass of cordierite fine powder.

[0211] In step (3), the mixing time for preparing the premixed powder is 10 min.

[0212] The modified epoxy resin in step (3) is prepared by adding amphiphilic block copolymer P123 to the epoxy resin and stirring for 5 minutes to completely dissolve it, thereby obtaining the modified epoxy resin. The mass of amphiphilic block copolymer P123 accounts for 0.07% of the mass of the epoxy resin. The epoxy resin is type E-51, with an epoxy value of 0.51 eq / 100g and a viscosity of 12500 mPa·s. The manufacturer is Hubei Kemaidi Chemical Co., Ltd. The amphiphilic block copolymer P123 (EO... 20 PO 70 EO 20 The molecular weight is 5800. The manufacturer is Zhengzhou Aikem Chemical Co., Ltd. The added amphiphilic block copolymer P123 has its hydrophilic segment adsorbed on the powder surface and its hydrophobic segment forming steric hindrance, which can stabilize the slurry and completely decompose at high temperature without residue.

[0213] In step (3), the mass ratio of cordierite powder to modified epoxy resin is 2:1. Modified epoxy resin is added to the premixed powder and stirred for 20 minutes to prepare a uniformly dispersed prestressed layer slurry.

[0214] In step (3), the thickness of the prestressed layer is controlled to be 1 mm.

[0215] The drying process described in step (3) involves drying at 60°C for 24 hours.

[0216] In step (4), the quartz powder has a particle size of 500 mesh, is manufactured by Shijiazhuang Huideli Mineral Products Co., Ltd., and has SiO2 ≥ 99.5%; the borax has a particle size of 600 mesh, and the alumina is α-Al2O3 with a particle size of 1000 mesh.

[0217] The nano-zirconia mentioned in step (4) is ZrO2-3Y; the particle size of zircon sand is 500 mesh, and the chemical composition by mass percentage is as follows: ZrO2 66.5%, SiO2 32.0%, Fe2O3 0.8%, Al2O3 0.5%, TiO2 0.1%, CaO+MgO 0.1%.

[0218] The preparation method of spodumene-modified potassium feldspar in step (4) is as follows: spodumene and potassium feldspar are mixed at a mass ratio of 1:4 and added to a ball mill. The ball-to-material ratio is 2:1 and the rotation speed is 300 r / min. The mixture is wet-milled for 2 hours, passed through a 200-mesh sieve, and then dried at 105℃ for 6 hours. After that, it is placed in a muffle furnace and calcined at 1100℃ for 2 hours. After natural cooling, it is ball-milled again and passed through a 600-mesh sieve to obtain spodumene-modified potassium feldspar.

[0219] The spodumene has a particle size of 800 mesh and its chemical composition by mass percentage is as follows: Li2O 6.2%, SiO2 64.5%, Al2O3 26.0%, MgO 1.0%, CaO 0.3%, Fe2O3 0.8%, and loss on ignition 1.2%.

[0220] The potassium feldspar has a particle size of 800 mesh and its chemical composition by mass percentage is as follows: K2O 10.5%, SiO2 64.0%, Al2O3 18.5%, Na2O 3.0%, CaO 1.2%, Fe2O3 0.8%, and loss on ignition 2.0%.

[0221] In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, and alumina is 4.2:2.8:2.2:1.2.

[0222] In step (4), the mass of nano-zirconia accounts for 0.5% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; the mass of zircon sand accounts for 0.2% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; and the mass of polyethylene glycol accounts for 0.1% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina. The polyethylene glycol is PEG-6000 produced by Sanda Chemical (Nantong) Co., Ltd.

[0223] In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand, polyethylene glycol, and deionized water is 1:1.2.

[0224] In step (4), the speed of the high-speed dispersant is 3000 r / min and the stirring time is 45 min.

[0225] In step (4), the electrostatic voltage for electrostatic spraying is 80kV.

[0226] In step (4), the thickness of the glaze layer on one side is controlled to be 0.50 mm.

[0227] The step drying process described in step (4) is to dry at 40°C for 4 hours, then at 50°C for 8 hours, and finally at 60°C for 12 hours.

[0228] The high-pressure ceramic bushing prepared in step (4) with an in-situ whisker interface-prestressed synergistic reinforcement consists of, from the outside to the inside, a glaze layer, a prestressed layer, a transition layer, a bushing blank layer, and another glaze layer. An in-situ whisker interface layer is formed in the transition layer, which in turn forms a bonding network with the bushing blank layer and the prestressed layer. The high-pressure ceramic bushing prepared in Example 3 has a fracture toughness of 8.9 MPa·m measured using the single-sided notched beam method. 1 / 2 Its flexural strength is 273 MPa.

[0229] Figure 4 This is a SEM image (10.0 kV, 10.7 mm × 10.0 k SE, 5.00 μm scale bar) of in-situ mullite whiskers in the transition layer of Example 3. The microstructure of the mullite whiskers in the transition layer of Example 3 is shown. By comparing with images from Examples 1-2, differences in the degree of interweaving and size uniformity of the whiskers can be observed, reflecting the influence of raw material ratios and process details on whisker growth, and presenting the actual microstructure of the whiskers under these conditions. Although the whiskers can penetrate the cordierite particles in the prestressed layer, the degree of interlocking between the whiskers and the cordierite matrix is ​​weaker than in Examples 1 and 2 due to the affected uniformity of cordierite dispersion. However, it is visible that a large number of needle-like and fibrous mullite whiskers are distributed in the transition layer region. The whiskers are interwoven and interpenetrating, some penetrating into the micropores and grain gaps of the sleeve blank, and some embedded between the prestressed layer particles, showing a radial and interlaced microscopic distribution pattern. According to the scale measurement, the whisker diameter is about 0.4-1.0μm, the length is about 5-12μm, and the aspect ratio is about 12-20, which is within the whisker size range described in the invention, further proving the stability of the process. Even if the raw material ratio is slightly adjusted, the in-situ whisker interface layer that meets the requirements can still be generated.

[0230] Comparative Example 1

[0231] The preparation method of the high-pressure porcelain bushing described in Comparative Example 1 is the same as that in Example 1, the only difference being that no transition layer is provided. The high-pressure porcelain bushing prepared in Comparative Example 1 has a fracture toughness of 5.6 MPa·m measured by the single-sided notched beam method. 1 / 2 Its flexural strength is 172 MPa.

[0232] Comparative Example 2

[0233] The preparation method of the high-pressure porcelain bushing described in Comparative Example 2 is the same as that in Example 1, the only difference being that no prestressing layer is provided. The high-pressure porcelain bushing prepared in Comparative Example 2 has a fracture toughness of 5.2 MPa·m measured using the single-sided notched beam method. 1 / 2 Its flexural strength is 159 MPa.

[0234] Comparative Example 3

[0235] The preparation method of the high-pressure porcelain bushing described in Comparative Example 3 is the same as that in Example 1, the only difference being that no glaze layers are provided on both sides. The high-pressure porcelain bushing prepared in Comparative Example 3 exhibits a fracture toughness of 6.8 MPa·m after measurement using the single-sided notched beam method. 1 / 2 Its flexural strength is 227 MPa.

[0236] Comparative Example 4

[0237] The preparation method of the high-pressure porcelain bushing described in Comparative Example 4 is the same as that in Example 1, the only difference being that the raw materials of the prestressed layer and the transition layer remain the same, but their positions are interchanged. The high-pressure porcelain bushing prepared in Comparative Example 4 has a fracture toughness of 5.9 MPa·m measured by the single-sided notched beam method. 1 / 2 Its flexural strength is 209 MPa.

Claims

1. A method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement, characterized in that: (1) Preparation of casing blank Industrial grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass and nano zirconium oxide are mixed evenly and then dry-milled in a planetary ball mill for 10 hours. Triethanolamine is added during ball milling. The resulting mixture is passed through a 200-mesh sieve and then spray-granulated through a 60-mesh sieve. The granulated particles are dried and isostatically pressed to obtain the casing blank. (2) Preparation of the transition layer ① Mix mullite fine powder, p-Al2O3 and amorphous silicon powder evenly, then add nano-yttrium oxide and mix evenly to prepare a mixture; ② Add perfluoropolyether-based polysiloxane to the modified silica sol to prepare a modified silica sol containing perfluoropolyether-based polysiloxane; ③ Add the mixture to the modified silica sol containing perfluoropolyether-based polysiloxane and stir for 15 minutes. Then add mullite particles and continue mixing for 15 minutes to obtain a transition layer slurry. Spray the transition layer slurry evenly onto the outer wall of the casing blank and dry it to prepare a casing blank containing a transition layer. (3) Preparation of prestressed layer Cordierite fine powder, nano-lanthanum oxide and nano-boron nitride fibers are mixed to prepare a premixed powder. Modified epoxy resin is added to the premixed powder and stirred evenly to prepare a prestressed layer slurry. The prestressed layer slurry is evenly sprayed onto the outer surface of the casing blank containing the transition layer and dried to prepare a casing blank containing the prestressed layer. (4) Quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand and polyethylene glycol are mixed evenly, and then deionized water is added. The mixture is stirred with a high-speed dispersant to form a glaze slurry. The glaze slurry is applied to the outer surface and inner surface of the prestressed casing blank by electrostatic spraying. The casing blank with a glaze layer is prepared by step drying process. (5) Sintering: The glazed sleeve blank is placed in a high-temperature furnace and heated to 1300℃ at a rate of 5℃ / min. It is then held for 2 hours for sintering to prepare a high-pressure ceramic sleeve containing in-situ whisker interface-prestress synergistic reinforcement.

2. The method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: The casing blank in step (1) is composed of the following raw materials: industrial grade bauxite, calcined kaolin, potassium feldspar powder, ball clay, high-purity modified water glass, nano-zirconia, and triethanolamine. The mass ratio of industrial grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay is 59.9: 34.9: 3.1: 2.

1. The mass of high-purity modified water glass accounts for 0.6% of the total mass of industrial grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of nano-zirconia accounts for 0.5% of the total mass of industrial grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. The mass of triethanolamine accounts for 0.1% of the total mass of industrial grade bauxite, calcined kaolin, potassium feldspar powder, and ball clay. In step (1), the particle size of the potassium feldspar powder is 200 mesh; The industrial-grade bauxite mentioned in step (1) has the following chemical composition by mass percentage: Al2O3 78.3%, SiO2 12.1%, Fe2O3 2.0%, TiO2 2.4%, CaO 0.3%, MgO 0.2%, K2O 0.2%, Na2O 0.1%, and loss on ignition 4.4%. The calcined kaolin described in step (1) has the following chemical composition by mass percentage: Al2O3 44.5%, SiO2 52.6%, Fe2O3 0.4%, TiO2 0.8%, CaO 0.2%, MgO 0.1%, K2O 0.2%, Na2O 0.1%, and loss on ignition 1.1%.

3. The method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: In step (1), alumina balls are used as the grinding medium during ball milling, and the ball-to-material ratio is 3:

1. In step (1), the drying temperature is 80℃, the drying time is 12h, the isostatic pressing pressure is 120MPa, and the holding time is 3min.

4. The method for preparing a high-pressure ceramic bushing containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: In step (2), the mass ratio of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder is 2.8-3.2 : 2.8-3.2 : 1.8-2.2 : 1.8-2.2; the mass of nano-yttrium oxide accounts for 0.8% of the total mass of mullite particles, mullite fine powder, ρ-Al2O3, and amorphous silicon powder. In step (2) ②, the mass of perfluoropolyether-based polysiloxane accounts for 0.03-0.07% of the mass of the modified silica sol; The modified silica sol in step (2) is prepared as follows: 1000g of ordinary silica sol with a SiO2 mass fraction of 30wt.% is stirred at a constant temperature of 50℃, and then boric acid solution is added. The mass concentration of boric acid solution is 5wt.%. The amount of boric acid added is controlled so that the concentration of B2O3 in the final modified silica sol is 0.5wt.% and the B2O3 content in the boric acid is 56.45%. 132.8g of boric acid solution needs to be added. The boric acid solution is added dropwise over 10min, and the stirring speed is 300r / min. Then, 50g of a mixture of anhydrous ethanol and γ-aminopropyltriethoxysilane is added at a dropping rate of 1 drop / second. Finally, the mixture is stirred at 50℃ for 2h. After cooling, the SiO2 content is adjusted to 40wt.% by evaporating water to prepare the modified silica sol.

5. The method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: The drying described in step (2) ③ is drying at 60℃ for 12 hours; In step (2) ③, the thickness of the transition layer is controlled to be 1 mm.

6. The method for preparing a high-pressure ceramic bushing containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: The chemical composition of the cordierite powder mentioned in step (3) is Mg2Al4Si5O. 18 The particle size is 500 mesh and the D50 is 1.8 μm. The surface activation process is as follows: First, the cordierite fine powder is completely immersed in a 10 wt% nitric acid solution and soaked at room temperature for 12 hours. After soaking, the fine powder is taken out and rinsed with deionized water 3 times. Then, it is placed in an oven at 110°C and dried for 3 hours. The dried cordierite fine powder is placed in a muffle furnace and calcined at a high temperature of 550°C for 4 hours. The nano-lanthanum oxide has a particle size of 35 nm, and the nano-boron nitride fiber has a diameter of 160 nm and an aspect ratio of 28. In step (3), the mass of nano-lanthanum oxide accounts for 0.3-0.7% of the mass of cordierite fine powder, and the mass of nano-boron nitride fiber accounts for 0.2-0.4% of the mass of cordierite fine powder; In step (3), the mixing time for preparing the premixed powder is 10 min.

7. The method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: The modified epoxy resin in step (3) is prepared by adding amphiphilic block copolymer P123 to the epoxy resin and stirring for 5 minutes to completely dissolve it, thereby obtaining the modified epoxy resin. The mass of amphiphilic block copolymer P123 accounts for 0.03-0.07% of the mass of epoxy resin. The epoxy resin is of type E-51 with an epoxy value of 0.51eq / 100g and a viscosity of 12500mPa·s. In step (3), the mass ratio of cordierite powder to modified epoxy resin is 2:

1. Modified epoxy resin is added to the premixed powder and stirred for 20 minutes to prepare a uniformly dispersed prestressed layer slurry. In step (3), the thickness of the prestressed layer is controlled to be 1 mm; The drying process described in step (3) involves drying at 60°C for 24 hours.

8. The method for preparing a high-pressure ceramic bushing containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: In step (4), the quartz powder has a particle size of 500 mesh, the borax has a particle size of 600 mesh, and the alumina is α-Al2O3 with a particle size of 1000 mesh. The nano-zirconia mentioned in step (4) is ZrO2-3Y, and the zircon sand has a particle size of 500 mesh. The chemical composition by mass percentage is as follows: ZrO2 66.5%, SiO2 32.0%, Fe2O3 0.8%, Al2O3 0.5%, TiO2 0.1%, CaO+MgO 0.1%; The preparation method of spodumene-modified potassium feldspar in step (4) is as follows: spodumene and potassium feldspar are mixed at a mass ratio of 1:4 and added to a ball mill. The ball-to-material ratio is 2:1 and the rotation speed is 300 r / min. The mixture is wet-milled for 2 hours, passed through a 200-mesh sieve, and then dried at 105℃ for 6 hours. After that, it is placed in a muffle furnace and calcined at 1100℃ for 2 hours. After natural cooling, it is ball-milled again and passed through a 600-mesh sieve to obtain spodumene-modified potassium feldspar. In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, and alumina is 3.8-4.2 : 2.8-3.2 : 1.8-2.2 : 0.8-1.

2.

9. The method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: In step (4), the mass of nano-zirconia accounts for 0.5% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; the mass of zircon sand accounts for 0.2-0.4% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina; and the mass of polyethylene glycol accounts for 0.05%-0.1% of the total mass of quartz powder, spodumene-modified potassium feldspar, borax, and alumina. In step (4), the mass ratio of quartz powder, spodumene-modified potassium feldspar, borax, alumina, nano-zirconia, zircon sand, polyethylene glycol, and deionized water is 1:1.

2.

10. The method for preparing a high-pressure ceramic sleeve containing an in-situ whisker interface-prestressed synergistic reinforcement as described in claim 1, characterized in that: In step (4), the speed of the high-speed dispersant is 3000 r / min and the stirring time is 45 min; The electrostatic voltage for electrostatic spraying in step (4) is 60-80kV; In step (4), the thickness of the glaze layer on one side is controlled to be 0.50 mm; The step drying process described in step (4) is to dry at 40°C for 4 hours, then at 50°C for 8 hours, and finally at 60°C for 12 hours. The high-pressure ceramic bushing prepared in step (4) consists of, from the outside to the inside, a glaze layer, a prestress layer, a transition layer, a bushing blank layer, and a glaze layer; an in-situ whisker interface layer is formed in the transition layer, and a bonding network is formed with the bushing blank layer and the prestress layer.

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