Vacuum interrupter metallized ceramic shell and its processing technology

Abstract

This invention belongs to the field of ceramic equipment manufacturing technology, and discloses a metallized ceramic shell for a vacuum interrupter and its processing technology. The process uses low-sodium α-alumina with 0.5~1μm grain size as raw material, and acid washing improves its chemical purity and grain boundary stability. During granulation, the moisture content is controlled to ≤0.1%, and homogenization is used to remove iron and eliminate conductive impurities. A drying process is added between pressing and turning to improve processing precision. Through programmed temperature sintering combined with atmosphere control, the crystal structure is optimized and organic matter and gases are expelled, avoiding closed pore defects. After firing, polishing reduces surface roughness and prevents dust adsorption and conductivity. The glazing process uses bentonite and silica to adjust the glaze viscosity, ensuring uniform glaze coverage and matching the thermal expansion of the ceramic body, improving the outer surface insulation performance. The synergistic effect of each step comprehensively improves the purity, density, and surface quality of the ceramic shell, effectively meeting the stringent insulation strength requirements of high-voltage vacuum interrupters.

Description

Technical Field

[0001] This invention belongs to the field of ceramic equipment manufacturing technology, and relates to a metallized ceramic shell for a vacuum interrupter and its processing technology. Background Technology

[0002] Vacuum interrupters, with their unique advantages, have been widely used in the medium- and high-voltage power transmission and distribution industry. They effectively extinguish electric arcs, ensuring the safe operation of power equipment during circuit interruption and greatly improving the reliability and stability of the power system. Currently, vacuum interrupters are mainly used at voltage levels of 12kV and 35kV, with only a small number applied to higher voltage levels such as 72.5kV, 126kV, and even 252kV. However, with the growing awareness of environmental protection, the demand for environmentally friendly interrupters is increasing, making the development of vacuum interrupters with higher voltage levels an inevitable trend in the industry.

[0003] Metallized ceramic shells, also known as metallized porcelain shells, are key components of vacuum interrupters, undertaking important functions such as insulation, support, and airtightness. Their performance directly affects the overall performance of the vacuum interrupter. However, under current technological conditions, existing metallized porcelain shells have many problems, especially in applications with higher voltage levels, where these drawbacks become increasingly apparent. As voltage levels increase, under the influence of extremely strong electric fields, even minor defects inside the metallized porcelain shell are magnified. For example, pores sealed inside the shell, while having a small impact at low voltage levels, can become areas of concentrated electric field in high-voltage, strong electric field environments, triggering partial discharge. Trace impurities in the shell, such as potassium, sodium, iron, and other foreign matter, can alter the electrical properties of the shell, damaging its insulation characteristics. Inhomogeneous crystal structure leads to uneven stress distribution within the shell, reducing its mechanical strength. Excessive surface roughness easily attracts dust and moisture, forming conductive channels and increasing the risk of leakage. These defects, when combined, can easily trigger avalanche phenomena, ultimately leading to insulation failure. Therefore, the performance of metallized ceramic shells commonly used for 12kV is no longer sufficient to meet the requirements of high-voltage vacuum interrupters. It is urgent to develop a metallized ceramic shell suitable for high-voltage vacuum interrupters. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a metallized ceramic shell for a vacuum interrupter and its processing technology, thereby solving the technical problem that the metallized ceramic shell in the prior art cannot meet the requirements of high-voltage vacuum interrupters.

[0005] This invention is achieved through the following technical solution: A processing method for a metallized ceramic shell for a vacuum interrupter includes the following steps: The α-alumina is acid-washed, and the acid-washed α-alumina is added to pure water to prepare a uniform suspension; the sodium content of the α-alumina is <0.05%, and the grain size is 0.5~1μm; Granulated material is prepared by suspension, wherein the moisture content of the granulated material is ≤0.1%; during the stirring process, lubricating liquid is sprayed into the granulated material, and after stirring and homogenization, homogenized granulated material is obtained, wherein the moisture content of the homogenized granulated material is 1.0%~1.5%; the homogenized granulated material is subjected to electromagnetic iron removal to obtain iron-removed granulated material. The granulated material after iron removal is pressed, dried and turned to obtain a blank. Under air atmosphere, the blank after the blank is subjected to programmed temperature rise sintering treatment to obtain a ceramic matrix; The ceramic substrate is polished and then glazed to obtain the metallized ceramic shell of the vacuum interrupter; during the glazing process, the glaze slurry contains bentonite and silicon dioxide.

[0006] Preferably, when granules are obtained from suspension, they are dried in a drying tower with an inlet temperature of 230~290℃ and an outlet temperature of 70~130℃. The inlet and outlet air volumes are adjusted to make the negative pressure in the drying chamber 10~200Pa.

[0007] Preferably, the stirring and homogenization time is 6-8 hours.

[0008] Preferably, the lubricant is composed of pure water and an organic lubricant; the conductivity of the pure water is <0.1 μs / cm.

[0009] Preferably, during electromagnetic iron removal, the output magnetic flux density is greater than 1T, and the feeding rate of the homogenized granulated material is 2t / h.

[0010] Preferably, during the pressing, drying and turning process of the granulated material after iron removal, the drying process specifically involves: placing the blank obtained from the pressing process vertically for drying at a temperature of 100~120℃ for 4~6 hours.

[0011] Preferably, the blank after machining is subjected to programmed temperature rise sintering treatment, specifically: the temperature is raised from room temperature to 400°C at a rate of 0.5°C / min, then raised from 400°C to 800°C at a rate of 0.8°C / min, and held at 800°C for 6 hours to ensure sufficient decomposition of organic matter and orderly transformation of crystal phase; the temperature is raised from 800°C to 1300°C at a rate of 0.8°C / min, then raised from 1300°C to 1650°C at a rate of 1°C / min, and held at 1650°C for 3 hours to complete the sintering treatment.

[0012] Preferably, the glaze slurry comprises potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silicon dioxide; by mass percentage, the glaze slurry comprises 70%~85% potassium feldspar, 0.5%~4% calcium carbonate, 0.5%~4% zirconium dioxide, 8%~15% bentonite, and 5%~15% silicon dioxide.

[0013] A metallized ceramic shell for a vacuum interrupter is manufactured using the process described above.

[0014] A vacuum interrupter is made by means of a metallized ceramic shell for a vacuum interrupter as described above.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a processing technology for the metallized ceramic shell of a vacuum interrupter. The process first uses α-alumina with extremely low sodium content and a grain size of 0.5~1μm, treated by acid washing, as the base raw material. Strict control of impurities in the raw material enhances chemical purity and grain boundary stability from the material's origin, laying the foundation for high insulation strength. Secondly, in the granulation stage, the moisture content of the granulated material is strictly controlled to ≤0.1%, and the moisture content is further controlled to 1.0%~1.5% through a subsequent homogenization process. Combined with an iron removal process, iron and micron-sized impurities are thoroughly removed, controlling the moisture content and compositional uniformity of the granulated material and eliminating the risk of conductive foreign matter. Finally, a drying process is added between the pressing and turning processes to improve... The precision of the blank is achieved through several steps. Then, through programmed heating and sintering with atmosphere adjustment, the ceramic crystal structure is optimized, fully expelling organic matter and gases from the blank and preventing potential problems such as closed pores caused by pre-sintering of the ceramic surface, thus ensuring the ceramic's insulation strength. Combined with post-firing polishing, surface roughness is significantly reduced, preventing dust adsorption and the formation of conductive channels. Furthermore, in the glazing stage, bentonite and silica are added to the glaze to adjust its viscosity, ensuring uniform glaze coverage and matching the ceramic's thermal expansion coefficient, thereby improving the insulation strength of the outer surface of the ceramic shell. In summary, this invention, through the effective synergy of various process steps, fully solves the technical problem that metallized ceramic shells in existing technologies cannot meet the requirements of high-voltage vacuum interrupters.

[0016] Furthermore, when granules are obtained from suspension, they are dried in a drying tower. The inlet temperature of the drying tower is 230~290℃, and the outlet temperature is 70~130℃. The inlet and outlet air volumes are adjusted to maintain a negative pressure of 10~200Pa in the drying chamber. By precisely controlling the inlet and outlet air temperatures and the negative pressure in the drying tower, the drying process of the granules can be effectively managed, avoiding excessively high or low moisture content, ensuring the stability and consistency of the granules, and thus improving the reliability of subsequent processing and product performance.

[0017] Furthermore, the mixing and homogenization time is 6-8 hours. The long mixing and homogenization time ensures the uniform distribution of each component in the granulated material, eliminates the problem of uneven local components, improves the overall quality and consistency of the granulated material, and provides a stable raw material basis for subsequent processing.

[0018] Furthermore, the lubricant is composed of pure water and an organic lubricant; the conductivity of the pure water is <0.1μs / cm. Using pure water with low conductivity mixed with an organic lubricant as a lubricant reduces the impact of impurities on ceramic properties and provides good lubrication, which helps to reduce friction during granulation and pressing processes and improve product quality.

[0019] Furthermore, during electromagnetic iron removal, the output magnetic flux density is greater than 1T, and the feeding rate of the homogenized granules is 2t / h. The high magnetic flux density and appropriate feeding rate ensure the high efficiency and thoroughness of the electromagnetic iron removal process, effectively removing iron impurities from the granules, improving the insulation performance and mechanical strength of the ceramics, and reducing the risk of product failure during use.

[0020] Furthermore, during the pressing, drying, and turning processes of the granulated material after iron removal, the drying process specifically involves placing the blank obtained from the pressing process vertically for drying at a temperature of 100~120℃ for 4~6 hours. This setting ensures uniform evaporation of moisture inside the blank, avoids drying cracks or deformation caused by residual moisture, and improves the processing accuracy and yield of the blank.

[0021] Furthermore, the blank after machining is subjected to programmed temperature sintering treatment, specifically: the temperature is increased from room temperature to 400℃ at a rate of 0.5℃ / min, then increased from 400℃ to 800℃ at a rate of 0.8℃ / min, and held at 800℃ for 6 hours to ensure sufficient decomposition of organic matter and orderly transformation of crystal phase; the temperature is increased from 800℃ to 1300℃ at a rate of 0.8℃ / min, then increased from 1300℃ to 1650℃ at a rate of 1℃ / min, and held at 1650℃ for 3 hours to complete the sintering treatment. This process ensures uniform heating and slow cooling of the ceramic blank during sintering, avoiding cracking or deformation caused by thermal stress, while promoting orderly transformation of crystal phase and sufficient decomposition of organic matter, thus improving the density and insulation properties of the ceramic.

[0022] Furthermore, the glaze slurry comprises potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silicon dioxide; by mass percentage, the glaze slurry comprises 70%~85% potassium feldspar, 0.5%~4% calcium carbonate, 0.5%~4% zirconium dioxide, 8%~15% bentonite, and 5%~15% silicon dioxide. The formulation design of this glaze slurry, through precise control of the proportion of each component, ensures uniform coverage of the glaze layer, good adhesion, and thermal expansion matching with the ceramic body, thereby improving the outer surface insulation performance and corrosion resistance of the ceramic shell and extending the service life of the product. Detailed Implementation

[0023] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0024] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0025] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0026] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0027] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0028] The preparation of conventional 12kV metallized ceramic shells follows a classic ceramic processing and metallization process. First, the ceramic raw materials are prepared into a uniform suspension through a slurry preparation process. This suspension is then spray-granulated into spherical particles to improve flowability. The powder is then pressed into a specific shape and machined (turning) to achieve precise dimensional correction. The blanks are then fired at high temperatures to form a dense ceramic matrix. After sintering, the ceramic parts undergo grinding to eliminate surface defects, providing a smooth base for subsequent glazing. After glazing, a second high-temperature firing (glaze firing) is required to form a glassy protective layer, enhancing insulation performance. Next, a metallizing paste is applied, and a high-temperature reduction reaction forms a metallic glaze layer on the ceramic shell surface, achieving a metallurgical bond between ceramic and metal. Electroplating further enhances the corrosion resistance of the metal layer, and finally, a second metallization process and packaging are completed. While this process can meet the requirements of 12kV voltage level, it has obvious limitations in high-voltage scenarios: microscopic defects such as closed pores, trace impurities (such as potassium and sodium ions) and surface roughness are prone to partial discharge in strong electric fields, and internal stress concentration caused by crystal inhomogeneity may cause cracks. Ultimately, insulation breakdown is caused by the superposition of defects, making it difficult to meet the stringent requirements of higher voltage levels for material performance.

[0029] To address the aforementioned problems, this invention provides a processing technology for the metallized ceramic shell of a vacuum interrupter, the specific process being as follows: 1. Pulping Alumina with a grain size of 0.5~1μm is acid-washed, and the acid-washed alumina is added to pure water to prepare a uniform suspension; the sodium content of the alumina is <0.05%, and the conductivity of the pure water is <0.1μs / cm; here the conductivity of the pure water is <0.1μs / cm.

[0030] Here, α-alumina with a lower sodium content is selected, and acid washing pretreatment effectively removes iron impurities from the alumina. Combined with a finer original grain size design, it replaces the traditional ordinary α-alumina with an original grain size of 2~5μm. This not only significantly improves the insulation performance of the ceramic body but also lowers the subsequent sintering temperature and increases the bulk density of the ceramic body, laying the foundation for the product's insulation reliability. In the slurry preparation stage, high-purity water is used instead of conventional tap water as the dispersion medium, blocking the introduction of impurities such as calcium, magnesium, and chloride ions at the water source level, avoiding the formation of microscopic conductivity channels, and improving insulation. This process, through dual control of main material upgrades and medium purification, constructs a high-purity system from the source of raw materials, ensuring that the ceramic slurry achieves an optimized balance in terms of fluidity, solid content, and electrical performance stability. This provides a high-performance green body foundation for subsequent molding and firing processes, ultimately achieving a systematic improvement in the insulation strength of the metallized ceramic shell.

[0031] 2. Granulation, homogenization, and iron removal processes (1) Granulation process The suspension is granulated to obtain granulated material, wherein the moisture content of the granulated material is ≤0.1%; Specifically: When granulating material from suspension, it is dried and granulated in a drying tower. The inlet air temperature of the drying tower is controlled at 230~290℃, and the outlet air temperature is controlled at 70~130℃. The inlet and outlet air volumes are adjusted to maintain a negative pressure of 10~200Pa in the drying chamber, achieving ultra-low moisture content control of the granulated material (≤0.1%), significantly lower than the industry standard of 0.1%~0.5%. In traditional processes, the moisture content of the granulated material is easily fluctuated due to factors such as ambient temperature and humidity and storage time during storage and use, leading to decreased stability in subsequent processing. This invention adopts a strategy of "ultra-low moisture content and homogenization and compounding before use" to minimize the moisture content during the granulation stage, inhibiting particle agglomeration and hydrolytic migration of iron impurities. Before subsequent feeding, moisture is precisely replenished and mixing is strengthened through a homogenization and iron removal process, while magnetic separation technology is used to thoroughly remove iron particles. This method not only ensures the long-term storage stability of the granulated material, but also improves the uniformity of particle dispersion through homogenization treatment. Combined with the iron removal process, it further eliminates the potential harm of iron impurities to the insulation performance of ceramics, laying the foundation for the reliability of high-voltage metallized ceramic shells.

[0032] (2) Homogenization The moisture content of each batch of granulated material is determined, and lubricating liquid is sprayed into the batch of granulated material during the mixing process. After mixing and homogenization, homogenized granulated material is obtained, wherein the moisture content of the homogenized granulated material is 1.0%~1.5%. The homogenization time here is 6-8 hours; The lubricant is composed of pure water and organic lubricant; the conductivity of the pure water is <0.1 μs / cm. The amount of lubricant injected is determined based on the moisture content and weight of the batch of granulated material. The specific calculation process is as follows: The original moisture content of this batch of granulated material was Y0; The quality of this batch of granulated material is T0; The total mass of the added lubricant solution is T1 (the optimal dilution ratio of lubricant stock solution T2 to pure water T3 is 1:4, and the water content of the lubricant stock solution is 90%). because: T1 = T2 + T3 T2 / T3=1 / 4 (T2×0.9+T3+T0×Y0) / T0=0.003 but: T1 = 5 × (0.003T0 - T0 × Y0) / 4.9 T2 = (0.003T0 - T0 × Y0) / 4.9 T3 = 4 × (0.003T0 - T0 × Y0) / 4.9; In this invention, the homogenization process adopts a batch-by-batch dynamic control strategy. Specifically, the real-time moisture content of each batch of granulated material is accurately measured, and the required amount of high-purity water and organic lubricant stock solution is calculated based on the material weight data to prepare the lubricant.

[0033] In one specific example, more than 5 tons of granulated material were fed into a V-type mixer, and lubricating fluid was sprayed on top of the continuous stirring, allowing for thorough homogenization for 6-8 hours. This resulted in a stable moisture content of 1.0%-1.5% in the granulated material. This step involves precisely controlling the amount of water added to the granulated material with an ultra-low initial moisture content (≤0.1%), thereby stabilizing the final moisture content at 1.0%~1.5%, completely eliminating the moisture content fluctuation problem caused by storage period and environmental temperature and humidity in traditional processes. In addition, the organic lubricant is uniformly coated on the surface of the particles, significantly improving the powder flowability and ensuring the production of high-density, homogeneous green bodies during the pressing stage. The granulated material used in this process is essentially free of water and lubricant. It is homogenized by adding water and lubricant before use, ensuring a stable moisture content. The granulated material used in this process is not affected by factors such as storage time and storage environment, breaking through the industry's conventional fixed moisture content control mode.

[0034] (3) Iron removal process The homogenized granulated material is subjected to electromagnetic iron removal to obtain iron-removed granulated material. The electromagnetic iron removal here takes place in an electromagnetic separator with an output magnetic flux density greater than 1T. The vibration frequency is controlled to keep the feed rate at the iron removal inlet at 2t / h. The vibration frequency here refers to the vibration frequency of the screen. By controlling the vibration frequency of the screen, the flow rate of the granulated material, i.e., the feed rate, is indirectly controlled. If the flow rate is too low, the efficiency is low, the dispersion is too large, and the iron impurities do not have time to be adsorbed onto the magnet before entering the next process, thus failing to achieve an effective iron removal effect.

[0035] Specifically, during iron removal, the homogenized granulated material is placed in an electromagnetic separator. The power is turned on, and the current density is adjusted to ensure that the output magnetic flux density is above 1T. The vibration frequency is adjusted to maintain a feed rate of 2t / h at the iron removal inlet, and iron removal is performed twice. Here, the homogenized material continuously passes through the electromagnetic separator. By adjusting the current density to maintain a magnetic flux density above 1T, combined with a vibration feed rate of 2t / h, deep removal of iron impurities is achieved. Compared to traditional permanent magnet iron removal technology, the magnetic field strength of the electromagnetic solution can be quantitatively adjusted to adapt to the purification needs of raw materials with different levels of contamination. The magnetic medium is easy to clean; after power is cut off and demagnetization is performed, adsorbed impurities can be quickly removed, avoiding cross-contamination. At the same time, the two-pass iron removal significantly improves the iron phase separation efficiency, especially for the trace iron filings generated by equipment friction during granulation, which have a high capture capacity. The cleaned material after treatment is immediately transferred to a sealed container for storage, effectively preventing secondary contamination.

[0036] This process system achieves effective homogenization of moisture content, particle size, and composition through a homogenization process. In conjunction with the electromagnetic iron removal process, it fundamentally solves the uniformity problem and iron contamination risk in the preparation of high-purity ceramics, laying a material foundation for the reliability of high-voltage metallized ceramic shells.

[0037] 3. Pressing and turning process The iron-removed granulated material is pressed into a billet, thus completing the pressing process and obtaining a blank. The blank is then placed vertically for drying. Here, the drying temperature is 100~120℃ and the drying time is 4~6 hours. The dried blank is then turned within 8 hours to obtain the turned billet. Here, the present invention specifically adds a drying process after pressing and a control of the processing time interval. The specific implementation is as follows: the blanks after pressing are placed vertically in a constant temperature drying room at 100~120℃ for forced drying for 4~6 hours. Then, the dried blanks are strictly limited to be machined within 8 hours. If the time limit is exceeded, they must be dried again before they can be put into processing.

[0038] This process uses lubricant added during the pressing process to form a moisture balance system within the blank, which, when dried at 100-120℃, accelerates the uniform release of moisture, preventing localized stress concentrations or microcracks caused by natural drying. The vertical stacking design utilizes gravity to assist in the vertical migration of moisture, improving dehydration efficiency and reducing the risk of deformation. The dried blank is in a low-moisture, brittle state, and its hardness and machinability are extremely sensitive to moisture reabsorption. Prolonged exposure to humidity or extended storage time can lead to surface re-deliquescence, causing fluctuations in material removal rates during turning and resulting in dimensional inconsistencies. By setting an 8-hour processing window, moisture exchange between the blank and the environment is forcibly blocked. Combined with a re-drying mechanism, this ensures consistent initial moisture content for each batch of blanks, eliminating interference factors such as tool wear fluctuations and cutting heat changes caused by differences in material hardness.

[0039] 4. Firing process The blank after the blank is turned is subjected to programmed temperature rise sintering treatment to obtain a ceramic matrix; The temperature rise sintering process here is as follows: In an air atmosphere, the temperature was increased from room temperature to 400℃ at a heating rate of 0.5℃ / min, then increased from 400℃ to 800℃ at a heating rate of 0.8℃ / min, and held at 800℃ for 6 hours to ensure full decomposition of organic matter and orderly transformation of crystal phase; the temperature was then increased from 800℃ to 1300℃ at a heating rate of 0.8℃ / min, then increased from 1300℃ to 1650℃ at a heating rate of 1℃ / min, and held at 1650℃ for 3 hours to complete the sintering process.

[0040] This invention achieves a breakthrough through a synergistic optimization strategy of slow heating, holding at key points, and strong oxidizing atmosphere control. Specifically, the heating stage employs an ultra-low rate: heating from room temperature to 400℃ at a rate of 0.5℃ / min, then from 400℃ to 800℃ at a rate of 0.8℃ / min, and holding at 800℃ for 6 hours to ensure sufficient decomposition of organic matter and orderly transformation of the crystal phase; heating from 800℃ to 1300℃ at a rate of 0.8℃ / min, then from 1300℃ to 1650℃ at a rate of 1℃ / min, and holding at 1650℃ for 3 hours to complete the sintering process. This process firstly achieves sufficient material migration in the low-temperature stage through long holding at 800℃, avoiding structural defects caused by rapid temperature rise; simultaneously, the forced introduction of preheated air throughout the process creates a strong oxidizing environment, utilizing waste heat heating technology to save energy and prevent cold air impact, promoting complete combustion of organic matter, effectively reducing the porosity of the ceramic and improving its insulation. This process significantly improves the microstructure uniformity and macroscopic performance stability of ceramic materials.

[0041] 5. Polishing process The ceramic substrate is polished to reduce the roughness of the inner surface of the ceramic substrate to ≤0.2μm; The polishing process is as follows: the rotation direction of the ceramic substrate is opposite to the rotation direction of the polishing medium, the rotation speed of the ceramic substrate is 10 RPM, the rotation speed of the polishing medium is 1000~1200 RPM; the polishing medium is a 1000-mesh diamond leaf wheel, and the polishing time is 25~35 minutes.

[0042] To further enhance the electrical performance of the ceramic shell in the vacuum interrupter, this invention introduces a high-precision inner surface polishing process after the sintering process. This process uses a 1000-mesh diamond blade as the polishing medium, achieving microscopic surface treatment through precision mechanical control: First, the sintered ceramic shell is fixed on a CNC polishing machine, its rotation speed is set to 10 RPM, and the cooling water circulation system is activated. Then, the diamond blade, rotating in the opposite direction to the ceramic shell's rotation, is started at a high speed of 1000-1200 RPM for reverse polishing. This dual-rotation reverse design generates a turbulent cutting effect, effectively eliminating microscopic protrusions and grain boundary defects formed during sintering. After 25-35 minutes of continuous polishing, the surface roughness of the ceramic shell's inner surface can be stably controlled at a mirror level of Ra≤0.2μm, an improvement of an order of magnitude compared to traditional processes. This ultra-smooth surface significantly improves the surface insulation of the inner surface, making it particularly suitable for manufacturing core insulating components of 126kV and above high-voltage vacuum circuit breakers, providing a crucial guarantee for the long-term operational reliability of the equipment.

[0043] 6. Glazing treatment The raw materials for the glaze are preheated, then added to water, along with bentonite and silica, and stirred until homogeneous to obtain a glaze slurry with a viscosity of 2000~3000 mPa·s. The glaze slurry is then uniformly coated onto the surface of a polished ceramic substrate, and finally sintered at high temperature to form a fully vitrified glaze layer.

[0044] The preheating temperature is 350~450℃. The purpose of preheating and baking the glaze raw materials at 350~450℃ is to remove moisture, crystal water and organic impurities from the raw materials and avoid the generation of bubbles or carbon residue during subsequent sintering.

[0045] The raw materials for the glaze include potassium feldspar, calcium carbonate, and zirconium dioxide; The high-temperature sintering temperature is 1430~1470℃, and the time is 2h; The glaze, by weight percentage, comprises 70% to 85% potassium feldspar, 0.5% to 4% calcium carbonate, 0.5% to 4% zirconium dioxide, 8% to 15% bentonite, and 5% to 15% silica.

[0046] The mass percentages here are based on the total mass of potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silica. Specifically, potassium feldspar accounts for 70%–85% of the total mass of potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silica. Calcium carbonate accounts for 0.5%–4% of the total mass of potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silica. Zirconium dioxide accounts for 0.5%–4% of the total mass of potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silica. Bentonite accounts for 8%–15% of the total mass of potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silica. Silica accounts for 5%–15% of the total mass of potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silica.

[0047] In the preparation of ceramic glazes, the traditional process employs a two-stage sintering method: organic binders (such as polyvinyl alcohol and carboxymethyl cellulose) are added to adjust the viscosity when preparing the glaze slurry. The glaze is first partially fired in an air furnace to form a semi-vitrified glaze layer. During this stage, only a portion of the organic matter in the glaze decomposes, and the remaining carbon elements form conductive channels. Subsequently, a high-temperature secondary sintering process is required in a hydrogen furnace to achieve full vitrification. While this process reduces the risk of glaze cracking, the residual organic matter in the semi-vitrification stage is easily carbonized in the hydrogen furnace, affecting the glaze's insulation properties.

[0048] This invention uses bentonite and silica to adjust the viscosity of the glaze slurry and fires the fully vitrified glaze at high temperature in an air furnace to completely burn off the organic matter and moisture in the glaze. This invention does not use organic binders; instead, it employs a bentonite-silica composite system. Utilizing the water absorption and expansion properties of the layered structure of bentonite and the nanoscale specific surface area of ​​silica, the rheological properties of the glaze slurry are adjusted through physical adsorption and mechanical thickening to ensure uniform glazing. Single-stage high-temperature sintering is performed in an electric air furnace. By precisely controlling the oxidizing atmosphere and temperature rise curve, the organic matter in the glaze is completely decomposed into CO2 and H2O, avoiding carbon residue and improving the insulation strength of the glaze layer.

[0049] In summary, this invention employs process optimization techniques to improve slurry uniformity during the pulping stage. A new homogenization and iron removal process utilizes magnetic separation and filtration to thoroughly remove iron and micron-sized impurities, eliminating the risk of conductive foreign matter at the source. During the firing process, segmented temperature control and atmosphere adjustment techniques optimize the ceramic's crystal structure, and combined with post-firing polishing, significantly reduce surface roughness, preventing dust adsorption and the formation of conductive channels. In the glazing stage, glaze pretreatment and formula optimization are implemented, developing a low-dielectric-loss glaze and adjusting the firing curve to ensure uniform glaze coverage and matching the ceramic's coefficient of thermal expansion. This invention utilizes higher purity and smaller particle size α-alumina as raw material, and employs pure water for slurry preparation to reduce the impact of trace impurities in the raw materials. This results in alumina ceramics with higher bulk density and insulation strength. The homogenization and iron removal processes before pressing improve the consistency of the granulated material, leading to more stable consistency in the pressed blanks. Pre-baking before turning maintains the consistency of blank size and performance, ensuring the consistency of the ceramic shell size and performance after firing. During the firing process, a strong oxidizing atmosphere is set to slow down the heating rate, fully expelling organic matter and gases from the blank, while preventing potential problems such as closed pores caused by pre-sintering on the ceramic surface, ensuring the ceramic's insulation strength. Combined with a more efficient and thorough polishing process, the smoothness of the inner surface of the ceramic shell is improved, thereby increasing the surface insulation strength inside the vacuum arc extinguishing chamber. Pre-treatment of the glaze, the use of bentonite and silica to adjust the viscosity and thixotropy of the glaze slurry without added organic matter, electric kiln firing, and fully vitrified glaze eliminate the possibility of glaze layer smoke, improving the outer surface insulation strength of the ceramic shell.

[0050] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0051] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0052] Example 1 A processing method for a metallized ceramic shell for a vacuum interrupter includes the following steps: 1. Pulping Alumina with a grain size of 0.5~1μm was acid-washed and then added to pure water to prepare a uniform suspension; the sodium content of the alumina was 0.045% and the conductivity of the pure water was <0.08 μs / cm. 2. Granulation, homogenization, and iron removal processes (1) Granulation process The suspension was granulated to obtain granulated material. In the granulation process, the inlet air temperature of the drying tower was controlled at 260℃ and the outlet air temperature at 100℃. The inlet and outlet air volumes were adjusted to make the negative pressure in the drying chamber 80Pa, so that the moisture content of the granulated material was 0.09%. (2) Homogenization The moisture content of each batch of granulated material was determined, and a lubricating liquid, including pure water and an organic lubricant, was sprayed into the batch of granulated material during the stirring process. The pure water had a conductivity of 0.09 μS / cm. After stirring and homogenizing for 8 hours, homogenized granulated material was obtained, with a moisture content of 1.0%. (3) Iron removal process The homogenized granulated material is subjected to electromagnetic iron removal to obtain iron-removed granulated material. Electromagnetic iron removal is carried out in an electromagnetic separator, with an output magnetic flux density greater than 1T. The vibration frequency is controlled to make the feed rate at the iron removal inlet 2t / h.

[0053] 3. Pressing and turning process The granulated material after iron removal is pressed into a blank, thus completing the pressing process and obtaining a blank. The blank is then placed vertically for drying. Here, the drying temperature is 120°C and the drying time is 4 hours. The dried blank is then turned within 8 hours to obtain the turned blank. 4. Firing process The blank after the blank is turned is subjected to programmed temperature rise sintering treatment to obtain a ceramic matrix; The temperature rise sintering process here is as follows: In an air atmosphere, the temperature was increased from room temperature to 400℃ at a heating rate of 0.5℃ / min, then increased from 400℃ to 800℃ at a heating rate of 0.8℃ / min, and held at 800℃ for 6 hours to ensure full decomposition of organic matter and orderly transformation of crystal phase; the temperature was then increased from 800℃ to 1300℃ at a heating rate of 0.8℃ / min, then increased from 1300℃ to 1650℃ at a heating rate of 1℃ / min, and held at 1650℃ for 3 hours to complete the sintering process.

[0054] 5. Polishing process The ceramic substrate is polished to achieve a surface roughness of 0.12 μm on its inner surface. Specifically, the ceramic substrate is rotated in the opposite direction to the polishing medium, with the ceramic substrate rotating at 10 RPM and the polishing medium rotating at 1000-1200 RPM. The polishing medium is a 1000-mesh diamond wheel, and the polishing time is 30 min.

[0055] 6. Glazing treatment The raw materials for the glaze, namely potassium feldspar, calcium carbonate and zirconium dioxide, are preheated at 400°C, then added to water, along with bentonite and silicon dioxide, and stirred evenly to obtain a glaze slurry with a viscosity of 2050 mPa·s. The glaze slurry is then evenly coated onto the surface of a polished ceramic substrate, and the substrate is then sintered at 1450°C for 2 hours to form a fully vitrified glaze layer.

[0056] The glaze slurry comprises, by mass percentage, 76.5% potassium feldspar, 1% calcium carbonate, 1.5% zirconium dioxide, 11% bentonite, and 10% silica.

[0057] 7. The product obtained after completing the above steps is coated with paste, subjected to primary metallization, electroplating, secondary metallization, and packaged to obtain the metallized ceramic shell of the vacuum interrupter.

[0058] Among them, screen printing, or paste application, is specifically as follows: the prepared molybdenum-manganese metallizing paste is applied to both ends of the ceramic shell using screen printing transfer technology, and then dried after being kept at 120±10℃ for 1 hour. The primary metallization process involves sintering a ceramic shell coated with metallizing paste using a vertical or horizontal hydrogen-protected furnace. The temperature is increased from room temperature to 800°C at a rate of 5-10°C / min and held for 30 minutes. Then, the temperature is increased from 800°C to 1450°C at a rate of 5-10°C / min and held for 100 minutes, followed by furnace cooling. During the heating, holding, and cooling processes above 1200°C, the furnace is filled with 45°C wet hydrogen. When the temperature drops below 1200°C, the furnace is filled with dry hydrogen.

[0059] The electroplating process specifically involves: after initial metallization, the ceramic shell is activated with 10% dilute hydrochloric acid for 10 seconds, rinsed with deionized water, and then plated with dark nickel at a current density of 0.3~0.8 A / dm³. 2 Electroplating for 2 hours, followed by two-stage water washing, deionized water rinsing, and hot air drying at 80~100℃.

[0060] The secondary metallization process involves: the nickel-plated ceramic shell is subjected to hydrogen burning treatment again in a vertical or horizontal hydrogen-protected furnace, with the temperature increased from room temperature to 850°C at a rate of 5~10°C / min, held for 30 minutes, and then cooled down with the furnace.

[0061] The packaging process is as follows: the ceramic shell that has undergone secondary metallization is placed inside a custom-made clean plastic shell, and then the plastic shell and the product are placed into a sealed plastic bag with a desiccant inside. After vacuum sealing, the product is placed in a packaging box and packaged.

[0062] Seven sets of samples were prepared in parallel for testing.

[0063] Example 2 A processing method for a metallized ceramic shell for a vacuum interrupter includes the following steps: 1. Pulping Alumina with a grain size of 0.5~1μm was acid-washed and then added to pure water to prepare a uniform suspension; the sodium content of the alumina was 0.04%, and the conductivity of the pure water was 0.09 μs / cm. 2. Granulation, homogenization, and iron removal processes (1) Granulation process The suspension was granulated to obtain granulated material. In the granulation process, the inlet air temperature of the drying tower was controlled at 230℃ and the outlet air temperature at 70℃. The inlet and outlet air volumes were adjusted to ensure that the negative pressure in the drying chamber was 10Pa, so that the moisture content of the granulated material was <0.06%. (2) Homogenization The moisture content of each batch of granulated material was determined, and a lubricating liquid, including pure water and an organic lubricant, was sprayed into the batch of granulated material during the stirring process; the conductivity of the pure water was <0.09 μs / cm. After stirring and homogenizing for 6 hours, homogenized granulated material was obtained, and the moisture content of the homogenized granulated material was 1.2%. (3) Iron removal process The homogenized granulated material is subjected to electromagnetic iron removal to obtain iron-removed granulated material. Electromagnetic iron removal is carried out in an electromagnetic separator, with an output magnetic flux density greater than 1T. The vibration frequency is controlled to make the feed rate at the iron removal inlet 2t / h.

[0064] 3. Pressing and turning process The granulated material after iron removal is pressed into a blank, thus completing the pressing process and obtaining a blank. The blank is then placed vertically for drying. Here, the drying temperature is 100℃ and the drying time is 6 hours. The dried blank is then turned within 8 hours to obtain the turned blank. 4. Firing process The blank after the blank is turned is subjected to programmed temperature rise sintering treatment to obtain a ceramic matrix; The temperature rise sintering process here is as follows: In an air atmosphere, the temperature was increased from room temperature to 400℃ at a heating rate of 0.5℃ / min, then increased from 400℃ to 800℃ at a heating rate of 0.8℃ / min, and held at 800℃ for 6 hours to ensure full decomposition of organic matter and orderly transformation of crystal phase; the temperature was then increased from 800℃ to 1300℃ at a heating rate of 0.8℃ / min, then increased from 1300℃ to 1650℃ at a heating rate of 1℃ / min, and held at 1650℃ for 3 hours to complete the sintering process.

[0065] 5. Polishing process The ceramic substrate is polished to achieve a surface roughness of 0.12 μm on its inner surface. Specifically, the ceramic substrate is rotated in the opposite direction to the polishing medium, with the ceramic substrate rotating at 10 RPM and the polishing medium rotating at 1000 RPM. The polishing medium is a 1000-mesh diamond wheel, and the polishing time is 25 min.

[0066] 6. Glazing treatment The raw materials for the glaze, namely potassium feldspar, calcium carbonate and zirconium dioxide, are preheated at 350°C, then added to water, along with bentonite and silica, and stirred evenly to obtain a glaze slurry with a viscosity of 2000 mPa·s. The glaze slurry is then uniformly coated onto the surface of a polished ceramic substrate, and the substrate is sintered at 1430°C for 2 hours to form a fully vitrified glaze layer.

[0067] The glaze slurry comprises, by mass percentage, 70% potassium feldspar, 3% calcium carbonate, 3% zirconium dioxide, 14% bentonite, and 10% silica.

[0068] 7. The product obtained after completing the above steps is subjected to paste coating, primary metallization, electroplating, and secondary metallization to obtain the metallized ceramic shell of the vacuum interrupter. The specific process is the same as in Example 1.

[0069] Example 3 A processing method for a metallized ceramic shell for a vacuum interrupter includes the following steps: 1. Pulping Alumina with a grain size of 0.5~1μm was acid-washed and then added to pure water to prepare a uniform suspension; the sodium content of the alumina was 0.048% and the conductivity of the pure water was <0.08 μs / cm. 2. Granulation, homogenization, and iron removal processes (1) Granulation process The suspension was granulated to obtain granulated material. In the granulation process, the inlet air temperature of the drying tower was controlled at 290℃ and the outlet air temperature at 130℃. The inlet and outlet air volumes were adjusted to ensure that the negative pressure in the drying chamber was 200Pa, so that the moisture content of the granulated material was <0.05%. (2) Homogenization The moisture content of each batch of granulated material was determined, and a lubricating liquid, including pure water and an organic lubricant, was sprayed into the batch of granulated material during the mixing process. The pure water had a conductivity of 0.08 μs / cm. After stirring and homogenizing for 8 hours, homogenized granulated material was obtained, with a moisture content of 1.5%. (3) Iron removal process The homogenized granulated material is subjected to electromagnetic iron removal to obtain iron-removed granulated material. Electromagnetic iron removal is carried out in an electromagnetic separator, with an output magnetic flux density greater than 1T. The vibration frequency is controlled to make the feed rate at the iron removal inlet 2t / h.

[0070] 3. Pressing and turning process The granulated material after iron removal is pressed into a blank, thus completing the pressing process and obtaining a blank. The blank is then placed vertically for drying. Here, the drying temperature is 120°C and the drying time is 4 hours. The dried blank is then turned within 8 hours to obtain the turned blank. 4. Firing process The blank after the blank is turned is subjected to programmed temperature rise sintering treatment to obtain a ceramic matrix; The temperature rise sintering process here is as follows: In an air atmosphere, the temperature was increased from room temperature to 400℃ at a heating rate of 0.5℃ / min, then increased from 400℃ to 800℃ at a heating rate of 0.8℃ / min, and held at 800℃ for 6 hours to ensure full decomposition of organic matter and orderly transformation of crystal phase; the temperature was then increased from 800℃ to 1300℃ at a heating rate of 0.8℃ / min, then increased from 1300℃ to 1650℃ at a heating rate of 1℃ / min, and held at 1650℃ for 3 hours to complete the sintering process.

[0071] 5. Polishing process The ceramic substrate is polished to achieve a surface roughness of 0.12 μm on its inner surface. Specifically, the ceramic substrate is rotated in the opposite direction to the polishing medium, with the ceramic substrate rotating at 10 RPM and the polishing medium rotating at 1200 RPM. The polishing medium is a 1000-mesh diamond wheel, and the polishing time is 35 min.

[0072] 6. Glazing treatment The raw materials for the glaze, namely potassium feldspar, calcium carbonate and zirconium dioxide, are preheated at 450°C, then added to water, along with bentonite and silica, and stirred evenly to obtain a glaze slurry with a viscosity of 3000 mPa·s. The glaze slurry is then uniformly coated onto the surface of a polished ceramic substrate, and the substrate is sintered at 1470°C for 2 hours to form a fully vitrified glaze layer.

[0073] The glaze slurry comprises, by mass percentage, 85% potassium feldspar, 1.5% calcium carbonate, 0.5% zirconium dioxide, 8% bentonite, and 5% silicon dioxide.

[0074] 7. The product obtained after completing the above steps is subjected to paste coating, primary metallization, electroplating, and secondary metallization to obtain the metallized ceramic shell of the vacuum interrupter. The specific process is the same as in Example 1.

[0075] Example 4 A processing method for a metallized ceramic shell for a vacuum interrupter includes the following steps: 1. Pulping Alumina with a grain size of 0.5~1μm was acid-washed and then added to pure water to prepare a uniform suspension; the sodium content of the alumina was 0.04% and the conductivity of the pure water was 0.09 μs / cm. 2. Granulation, homogenization, and iron removal processes (1) Granulation process The suspension was granulated to obtain granulated material. In the granulation process, the inlet air temperature of the drying tower was controlled at 270℃ and the outlet air temperature at 110℃. The inlet and outlet air volumes were adjusted to ensure that the negative pressure in the drying chamber was 100Pa, so that the moisture content of the granulated material was <0.06%. (2) Homogenization The moisture content of each batch of granulated material was determined, and a lubricating liquid, including pure water and an organic lubricant, was sprayed into the batch of granulated material during the stirring process; the conductivity of the pure water was <0.09 μs / cm. After stirring and homogenizing for 8 hours, homogenized granulated material was obtained, and the moisture content of the homogenized granulated material was 1.2%. (3) Iron removal process The homogenized granulated material is subjected to electromagnetic iron removal to obtain iron-removed granulated material. Electromagnetic iron removal is carried out in an electromagnetic separator, with an output magnetic flux density greater than 1T. The vibration frequency is controlled to make the feed rate at the iron removal inlet 2t / h.

[0076] 3. Pressing and turning process The granulated material after iron removal is pressed into a blank, thus completing the pressing process and obtaining a blank. The blank is then placed vertically for drying. Here, the drying temperature is 120°C and the drying time is 4 hours. The dried blank is then turned within 8 hours to obtain the turned blank. 4. Firing process The blank after the blank is turned is subjected to programmed temperature rise sintering treatment to obtain a ceramic matrix; The temperature rise sintering process here is as follows: In an air atmosphere, the temperature was increased from room temperature to 400℃ at a heating rate of 0.5℃ / min, then increased from 400℃ to 800℃ at a heating rate of 0.8℃ / min, and held at 800℃ for 6 hours to ensure full decomposition of organic matter and orderly transformation of crystal phase; the temperature was then increased from 800℃ to 1300℃ at a heating rate of 0.8℃ / min, then increased from 1300℃ to 1650℃ at a heating rate of 1℃ / min, and held at 1650℃ for 3 hours to complete the sintering process.

[0077] 5. Polishing process The ceramic substrate is polished to achieve a surface roughness of 0.12 μm on its inner surface. Specifically, the ceramic substrate is rotated in the opposite direction to the polishing medium, with the ceramic substrate rotating at 10 RPM and the polishing medium rotating at 1100 RPM. The polishing medium is a 1000-mesh diamond leaf wheel, and the polishing time is 30 min.

[0078] 6. Glazing treatment The raw materials for the glaze, namely potassium feldspar, calcium carbonate and zirconium dioxide, are preheated at 400°C, then added to water, along with bentonite and silicon dioxide, and stirred evenly to obtain a glaze slurry with a viscosity of 2080 mPa·s. The glaze slurry is then uniformly coated onto the surface of a polished ceramic substrate, and the substrate is sintered at 1440°C for 2 hours to form a fully vitrified glaze layer.

[0079] The glaze slurry comprises, by mass percentage, 78.5% potassium feldspar, 1% calcium carbonate, 1.5% zirconium dioxide, 10% bentonite, and 9% silicon dioxide.

[0080] 7. Apply paste, perform primary metallization, electroplating, perform secondary metallization, and package, as detailed in Example 1.

[0081] Comparative Example 1 The metallized ceramic shell of the vacuum interrupter is prepared using existing technology. During the preparation process: The raw material is α-alumina with a diameter of 2-5 μm, and the slurry is prepared using tap water; The moisture content is directly controlled at 1.2% during granulation; the homogenization and iron removal process described in this invention is not performed after granulation. There is no drying process between the pressing and turning of the billet; The firing process is as follows: The temperature was increased from room temperature to 400℃ at a rate of 6℃ / min, from 400℃ to 900℃ at a rate of 8℃ / min, from 900℃ to 1200℃ at a rate of 5℃ / min, from 1200℃ to 1400℃ at a rate of 2.5℃ / min, and from 1400℃ to 1700℃ at a rate of 2.8℃ / min. Finally, the temperature was held at 1700℃ for 3 hours to complete the sintering.

[0082] Seven sets of samples were prepared in parallel for testing.

[0083] Table 1 shows the inner surface roughness of the metallized ceramic shell of the vacuum interrupter processed by existing processes and by Embodiment 1 of the present invention in Comparative Example 1. As can be seen from Table 1, the present invention improves the inner surface roughness of the metallized ceramic shell of the vacuum interrupter by an order of magnitude. In the subsequent processing and exhaust process of the vacuum interrupter, the inner surface is less likely to adsorb pollutants and gases, which is beneficial to maintaining the vacuum level of the vacuum interrupter and improving the inner surface's resistance to flashover breakdown.

[0084] Table 1 shows the inner surface roughness of the metallized ceramic shell of the vacuum interrupter processed by existing processes and Embodiment 1 of the present invention.

[0085] Furthermore, the mass of the metallized ceramic shell of the vacuum interrupter prepared by this invention was tested. Its bulk density, according to GB / T 2413-1981 standard, was measured using an electronic balance, and the result was 3.70 g / cm³. 3 The breakdown strength, tested with a DC high-voltage generator, reached 50 kV / mm. Meanwhile, the bulk density of the metallized ceramic shell of the vacuum interrupter, manufactured using existing processes, is 3.65 g / cm³. 3 The DC breakdown strength is 35 kV / mm. Therefore, it can be seen that the DC breakdown strength of the metallized ceramic shell for the vacuum interrupter prepared by this invention is more than 40% higher than that of the metallized ceramic shell for the vacuum interrupter prepared by existing processes. This provides a strong guarantee for improving the withstand voltage of vacuum interrupters with higher voltage levels.

[0086] Simultaneously, the insulation resistance of the inner surface of the metallized ceramic shell of the vacuum interrupter prepared by this invention was tested. The test process started from 60kV, with a voltage stabilization time of 1 minute and a voltage increase of 5kV each time. The highest voltage that it could withstand was tested. The flashover breakdown strength of the inner surface of the metallized ceramic shell of the vacuum interrupter prepared by Example 1 of this invention was 1.9kV / mm, which is 18% higher than the 1.6kV / mm of the inner surface of the metallized ceramic shell of the vacuum interrupter prepared by the existing process, providing the possibility for the vacuum interrupter to withstand higher voltage levels.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A processing technology for a metallized ceramic shell of a vacuum interrupter, characterized in that, Includes the following steps: The α-alumina is acid-washed, and the acid-washed α-alumina is added to pure water to prepare a uniform suspension; the sodium content of the α-alumina is <0.05%, and the grain size is 0.5~1μm; Granulated material is prepared by means of suspension, wherein the moisture content of the granulated material is ≤0.1%; Lubricating liquid is sprayed into the granulation material during the stirring process. After stirring and homogenization, homogenized granulation material is obtained. The moisture content of the homogenized granulation material is 1.0%~1.5%. The homogenized granulation material is subjected to electromagnetic iron removal to obtain iron-removed granulation material. The granulated material after iron removal is pressed, dried, and then machined to obtain a machined billet. Under air atmosphere, the blank after the blank is subjected to programmed temperature rise sintering treatment to obtain a ceramic matrix; After polishing the ceramic substrate, glazing is performed to obtain the metallized ceramic shell of the vacuum interrupter. During the glazing process, the glaze slurry contains bentonite and silicon dioxide.

2. The processing technology for a metallized ceramic shell of a vacuum interrupter according to claim 1, characterized in that, When granules are obtained from suspension, they are dried in a drying tower. The inlet temperature of the drying tower is 230~290℃, and the outlet temperature is 70~130℃. The inlet and outlet air volumes are adjusted to make the negative pressure in the drying chamber 10~200Pa.

3. The processing technology for a metallized ceramic shell of a vacuum interrupter according to claim 1, characterized in that, The stirring and homogenization time is 6-8 hours.

4. The processing technology for a metallized ceramic shell of a vacuum interrupter according to claim 1, characterized in that, The lubricant is composed of pure water and organic lubricant; the conductivity of the pure water is <0.1 μs / cm.

5. The processing technology for a metallized ceramic shell of a vacuum interrupter according to claim 1, characterized in that, When performing electromagnetic iron removal, the output magnetic flux density is greater than 1T, and the feeding rate of the homogenized granulated material is 2t / h.

6. The processing technology for a metallized ceramic shell of a vacuum interrupter according to claim 1, characterized in that, The granulated material after iron removal undergoes pressing, drying, and blank turning processes. Specifically, the drying process involves placing the blank obtained from pressing vertically for drying at a temperature of 100-120°C for 4-6 hours.

7. The processing technology for a metallized ceramic shell of a vacuum interrupter according to claim 1, characterized in that, The blank after turning is subjected to programmed temperature rise sintering treatment, specifically: the temperature is raised from room temperature to 400℃ at a rate of 0.5℃ / min, raised from 400℃ to 800℃ at a rate of 0.8℃ / min, and held at 800℃ for 6 hours, raised from 800℃ to 1300℃ at a rate of 0.8℃ / min, raised from 1300℃ to 1650℃ at a rate of 1℃ / min, and held at 1650℃ for 3 hours.

8. The processing technology for a metallized ceramic shell of a vacuum interrupter according to claim 1, characterized in that, The glaze slurry comprises potassium feldspar, calcium carbonate, zirconium dioxide, bentonite, and silicon dioxide; by mass percentage, the glaze slurry comprises 70% to 85% potassium feldspar, 0.5% to 4% calcium carbonate, 0.5% to 4% zirconium dioxide, 8% to 15% bentonite, and 5% to 15% silicon dioxide.

9. A metallized ceramic shell for a vacuum interrupter, characterized in that, It is prepared by the process described in any one of claims 1 to 8.

10. A vacuum interrupter, characterized in that, It is made by means of a metallized ceramic shell for a vacuum interrupter as described in claim 9.

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