A method for preparing current-carrying glaze for porcelain insulators

Abstract

This invention discloses a method for preparing a current-carrying glaze for porcelain insulators and a method for preparing porcelain insulators using the glaze. As the glassy layer on the surface of porcelain insulators, achieving uniform resistivity in the glaze is very difficult with existing technologies. Non-uniform resistivity leads to excessively high local temperatures, affecting the electrical performance of the insulator. The technical solution of this invention effectively controls the fineness and particle size distribution of the current-carrying compound through a step-by-step grinding and sintering process, thereby achieving uniform conductivity of the current-carrying compound at the microscopic level and its uniform distribution in the glaze. Simultaneously, through experimental verification, a reasonable ratio and glaze layer thickness are selected to achieve precise control of resistivity. This ensures that the glaze does not affect the electrical performance of the porcelain insulator while maintaining stable heating within the operating voltage range and preventing icing.

Description

Technical Field

[0001] This invention relates to the field of porcelain insulator glaze material technology, specifically a method for preparing a current-carrying glaze for porcelain insulators. Background Technology

[0002] Rod-shaped post porcelain insulators are key basic components in the power industry. They are mainly used in power plants, substations, power distribution equipment, and electrical equipment to support and insulate energized parts.

[0003] Insulator flashover is a form of insulation failure. Insulator flashover can be divided into overvoltage flashover and non-overvoltage flashover. Overvoltage flashover is generally caused by lightning or switching impulses, while non-overvoltage flashover is generally caused by changes in the insulation condition of the insulator, including pollution flashover and ice flashover.

[0004] Insulator flashover is caused by ice formation on the insulator surface, leading to a decrease in insulation strength. During ice melting, the water film on the ice surface or ice crystals quickly dissolves electrolytes from pollutants, increasing the conductivity of the meltwater or ice film and causing distortion in the voltage distribution of the insulator string. The rapid voltage increase at both ends of the insulator further distorts the voltage distribution on the surface of individual insulators, thus reducing the flashover voltage of the ice-covered insulator string. Simultaneously, the ice-melting period is often accompanied by heavy fog, where atmospheric pollutants act as condensation nuclei, further increasing the conductivity of the ice water as the insulator melts. When the leakage current increases to a certain level, a flashover path forms, causing the line to trip.

[0005] With the increasing frequency of extreme weather events due to global climate change in recent years, the possibility of icing on power transmission lines has increased, posing a challenge to the safe and stable operation of the power grid. Therefore, the icing problem of porcelain insulators is an urgent issue that needs to be addressed. Summary of the Invention

[0006] The present invention aims to at least partially overcome the above-mentioned technical problems and / or other potential problems existing in the prior art: to provide a method for preparing a current-carrying glaze for porcelain insulators and a method for preparing porcelain insulators using the current-carrying glaze, so as to achieve functional improvement of the glaze layer on the surface of the porcelain insulator, so that it can generate heat uniformly under operating voltage, and ensure that the heat generation does not affect other properties of the porcelain insulator.

[0007] The first objective of this invention is to provide a method for preparing a current-carrying glaze for porcelain insulators, comprising the following steps:

[0008] 1) Weigh the following components by weight and mix them to obtain the current carrier compound raw material: 20-70 parts of tin oxide, 20-70 parts of metastannic acid, 5-15 parts of antimony oxide, and 0.1-1 parts of calcium fluoride;

[0009] 2) The current carrier compound raw material obtained in step 1) is first ball-milled to obtain powder with a particle size D90 of 15-25 μm, and then ball-milled a second time to obtain current carrier compound powder with a particle size D50 of 0.5-0.6 μm;

[0010] 3) The current-carrying compound powder obtained in step 2) is calcined at 1250–1270 °C in an oxidizing atmosphere;

[0011] 4) The current-carrying compound powder after calcination in step 3) is first ball-milled to obtain a powder with a particle size D90 of 10-20 μm, and then ball-milled a second time to obtain a powder with a particle size D50 of 0.5-0.6 μm. The powder is then dried to obtain the current-carrying compound.

[0012] 5) Weigh the following raw materials in parts by weight: 10-30 parts feldspar, 5-20 parts frit, 10-20 parts quartz, 5-10 parts talc, 5-15 parts Zhangcun clay, 1-10 parts wollastonite, 5-15 parts kaolin, and 20-30 parts carrier compound.

[0013] 6) After mixing and ball milling the various raw materials from step 5) to a particle size ≤10um, the mixture is sieved, iron is removed, and aged for 48-72 hours to obtain the flow-carrying glaze.

[0014] The second objective of this invention is to provide a method for preparing a porcelain insulator, comprising the following steps:

[0015] 1) Add water to the prepared current-carrying glaze to adjust the specific gravity to 1.5-1.7 g / ml. Use a Forte 4 viscometer to measure the flow rate of the current-carrying glaze. Control the flow rate at 12-14 seconds. Immerse the porcelain insulator blank in the current-carrying glaze for 15-20 seconds and control the glaze thickness to 0.4-0.8 mm.

[0016] 2) Place the glazed porcelain insulator blank from step 1) into a kiln for firing. Use an oxidizing flame and fire at a maximum temperature of 1250-1270℃. The firing process is divided into four stages: low temperature stage, oxidation decomposition stage, high temperature stage, and cooling stage.

[0017] As an optimization, the low-temperature stage involves heating to 400°C at a heating rate of 20–30°C / h.

[0018] As an optimization, the oxidative decomposition stage involves heating from 400°C to 1000°C at a heating rate of 10–15°C / h.

[0019] As an optimization, the high-temperature stage is to raise the temperature from 1000°C to the maximum firing temperature at a heating rate of 20-40°C / h.

[0020] As an optimization, the cooling stage is divided into two stages: rapid cooling and slow cooling. The rapid cooling stage is from the highest firing temperature to 900℃, with a cooling rate controlled at 300-500℃ / h. The slow cooling stage is from 900℃ to room temperature, with a cooling rate controlled at 30-50℃ / h.

[0021] The beneficial effects of this invention are as follows: As the vitreous layer on the surface of porcelain insulators, achieving uniform resistivity in the glaze using existing technologies is extremely difficult. Uneven resistivity leads to excessively high local temperatures, affecting the electrical performance of the insulator. This invention's technical solution, through step-by-step grinding and sintering processes, effectively controls the fineness and particle size distribution of the current-carrying compound, thereby achieving uniform conductivity of the current-carrying compound at the microscopic level and its uniform distribution within the glaze. Simultaneously, through experimental verification, a reasonable ratio and glaze thickness are selected to achieve precise control of resistivity. This ensures that the glaze does not affect the electrical performance of the porcelain insulator while maintaining stable heating within the operating voltage range, preventing icing. Attached Figure Description

[0022] Figure 1 The image shown is an electron microscope image of the ceramic insulator prepared in Example 7. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following specific embodiments.

[0024] Example 1

[0025] Preparation of the current-carrying glaze:

[0026] 1) Weigh the following components by weight and mix them to obtain the current carrier compound raw material: 55 parts tin oxide, 35.5 parts metastannic acid, 9 parts antimony oxide, and 0.5 parts calcium fluoride;

[0027] 2) The raw materials from step 1) are mixed and ground for the first time in a ball mill with alumina balls and water at a weight ratio of 1:1.5:1. After mixing and grinding for a certain period of time, the particle size is measured with a BT9300H laser particle size analyzer to control the particle size D90: 20μm. After the particle size is qualified, the slurry is discharged and passed through a 60-mesh sieve (with ball stones). The slurry after the first grinding is placed in a sand mill for the second mixing and grinding. After mixing and grinding for a certain period of time, the particle size is measured with a BT9300H laser particle size analyzer to control the particle size D50: 0.6μm. After the particle size is qualified, the slurry is discharged into an enamel tray and placed in a drying oven or drying room for drying at a drying temperature of 100℃. After drying, the agglomerated dry material is pulverized by a pulverizer and the powder is passed through a 24-mesh sieve for later use.

[0028] 3) The current-carrying compound powder obtained in step 2) is loaded into a sagger and placed in a kiln to be fired at 1270°C in an oxidizing atmosphere;

[0029] 4) The calcined current-carrying compound powder from step 3) is mixed and ground once in a ball mill with alumina spherical stones and water at a weight ratio of 1:1.5:1. After a certain period of time, the particle size is measured using a BT9300H laser particle size analyzer to control the particle size D90:15μm. After the particle size is qualified, the slurry is discharged and passed through a 60-mesh sieve (with retaining stones). The slurry is then placed in a sand mill for a second mixing and grinding. After mixing and grinding for a certain period of time, the particle size is measured using a BT9300H laser particle size analyzer to control the particle size D50:0.6μm. After the particle size is qualified, the slurry is placed in an enamel tray and dried in a drying oven or drying room. After drying, it is ready for use. The preparation of the current-carrying compound is complete.

[0030] 5) Weigh the following raw materials in parts by weight: 25 parts feldspar, 10 parts frit, 10 parts quartz, 5 parts talc, 10 parts Zhangcun clay, 5 parts wollastonite, 5 parts kaolin, and 30 parts current-carrying compound.

[0031] 6) Place the various raw materials from step 5) with alumina spherical stones and water in a ball mill at a weight ratio of 1:1.5:0.8 and mix and grind for about 7 hours. Use a BT9300H laser particle size analyzer to measure the particle size and control the particle size to ≤10μm%. After the particle size is qualified, discharge the slurry through a 200-mesh sieve, remove iron with an iron remover, and then place it in a mixing tank for aging for 72 hours before use.

[0032] Example 2

[0033] Compared to Example 1, step 1) is as follows: Weigh the following components by weight and mix them to obtain the current carrier compound raw material: 40 parts tin oxide, 50 parts metastannic acid, 9.5 parts antimony oxide, and 0.5 parts calcium fluoride. Step 5) is as follows: Weigh the following raw materials by weight: 10 parts feldspar, 20 parts frit, 15 parts quartz, 5 parts talc, 10 parts Zhangcun clay, 5 parts wollastonite, 5 parts kaolin, and 30 parts current carrier compound. The rest of the contents are the same as in Example 1.

[0034] Example 3

[0035] Compared to Example 1, step 1) is as follows: Weigh the following components by weight and mix them to obtain the current carrier compound raw material: 60 parts tin oxide, 30 parts metastannic acid, 9.9 parts antimony oxide, and 0.1 parts calcium fluoride. Step 5) is as follows: Weigh the following raw materials by weight: 30 parts feldspar, 5 parts frit, 10 parts quartz, 5 parts talc, 10 parts Zhangcun clay, 5 parts wollastonite, 10 parts kaolin, and 25 parts current carrier compound. The rest of the contents are the same as in Example 1.

[0036] Example 4

[0037] Compared to Example 1, step 1) is as follows: Weigh the following components by weight and mix them to obtain the current carrier compound raw material: 70 parts tin oxide, 20 parts metastannic acid, 9 parts antimony oxide, and 1 part calcium fluoride. Step 5) is as follows: Weigh the following raw materials by weight: 30 parts feldspar, 10 parts frit, 10 parts quartz, 5 parts talc, 5 parts Zhangcun clay, 5 parts wollastonite, 5 parts kaolin, and 30 parts current carrier compound. The rest of the contents are the same as in Example 1.

[0038] Example 5

[0039] Compared to Example 1, step 1) is as follows: Weigh the following components by weight and mix them to obtain the current carrier compound raw material: 20 parts tin oxide, 70 parts metastannic acid, 9 parts antimony oxide, and 1 part calcium fluoride. Step 5) is as follows: Weigh the following raw materials by weight: 10 parts feldspar, 20 parts frit, 15 parts quartz, 5 parts talc, 10 parts Zhangcun clay, 5 parts wollastonite, 5 parts kaolin, and 30 parts current carrier compound. The rest of the contents are the same as in Example 1.

[0040] Example 6

[0041] Compared to Example 1, step 1) is as follows: Weigh the following components by weight and mix them to obtain the current carrier compound raw material: 60 parts tin oxide, 34 parts metastannic acid, 5.9 parts antimony oxide, and 0.1 parts calcium fluoride. Step 5) is as follows: Weigh the following raw materials by weight: 30 parts feldspar, 5 parts frit, 10 parts quartz, 5 parts talc, 15 parts Zhangcun clay, 5 parts wollastonite, 5 parts kaolin, and 25 parts current carrier compound. The rest is the same as in Example 1.

[0042] Example 7

[0043] The process of preparing porcelain insulators using the current-carrying glaze prepared in Example 1 includes the following steps:

[0044] 1) Add water to the current-carrying glaze prepared in Example 1 to adjust the specific gravity to 1.6 g / ml. Use a Forte 4 viscometer to measure the flow rate of the current-carrying glaze. Control the flow rate at 12 seconds. Rotate the porcelain insulator blank laterally and immerse it in the current-carrying glaze. Immersion time is 15 seconds. Control the glaze layer thickness to be 0.45-0.50 mm.

[0045] 2) The glazed porcelain insulator blanks from step 1) are placed in a kiln for firing in an oxidizing flame at a maximum firing temperature of 1270℃. The firing process is divided into four stages: a low-temperature stage, an oxidation-decomposition stage, a high-temperature stage, and a cooling stage. The low-temperature stage involves heating to 400℃ at a rate of 25℃ / h. The oxidation-decomposition stage involves heating from 400℃ to 1000℃ at a rate of 10℃ / h. The high-temperature stage involves heating from 1000℃ to 1270℃ at a rate of 30℃ / h. The cooling stage is divided into two phases: rapid cooling from 1270℃ to 900℃ (with a cooling rate controlled at 500℃ / h) and slow cooling from 900℃ to room temperature (with a cooling rate controlled at 40℃ / h).

[0046] In this embodiment, the porcelain insulator blank is a rod-shaped post insulator blank, and the cross-sectional electron microscope image of the prepared rod-shaped post insulator is shown below. Figure 1 As shown, Figure 1 The darker-colored part in the upper middle section with many small holes is made of porcelain material, while the part below with a clear interface is the glaze layer. The white dots in the glaze layer are the flow-carrying compounds, which can be seen to be evenly distributed in the glaze layer.

[0047] The leakage current measurement and thermal stability test were compared between the rod-shaped post insulator prepared in this embodiment and the rod-shaped post insulator prepared using conventional glaze.

[0048] 1. Leakage current measurement

[0049] Apply voltage 73kV, maximum duration: 360min.

[0050] The test results of the rod-shaped post insulators prepared in this embodiment are shown in Table 1, and the test results of the conventional glazed rod-shaped post insulators are shown in Table 2.

[0051] Table 1: Leakage Current Measurement - Rod Post Insulator in this Embodiment

[0052] Tolerance time (min) Leakage current (mA) 0 0.95 30 0.98 60 1.01 90 1.02 120 1.03 150 1.05 180 1.05 210 1.05 240 1.07 270 1.07 300 1.08 330 1.07 360 1.07

[0053] Table 2: Leakage Current Measurement - Conventional Enamelled Rod Post Insulators

[0054] Tolerance time (min) Leakage current (mA) 0 0.22 30 0.22 60 0.22 90 0.22 120 0.22 150 0.22 180 0.22 210 0.22 240 0.22 270 0.22 300 0.22 330 0.22 360 0.22

[0055] 2. Thermal stability test

[0056] Before the test, the surface temperature of the main body and the skirt of the test specimen were measured at three locations. Then, a voltage of 73kV was applied, and the surface temperature was recorded every 30 minutes. The test results of the rod-shaped post insulator prepared in this embodiment are shown in Table 3, and the test results of the conventional glazed rod-shaped post insulator are shown in Table 4.

[0057] Table 3: Thermal Stability Test - Rod Post Insulator of This Embodiment

[0058]

[0059] Table 4: Thermal Stability Test - Conventional Glazed Rod Post Insulators

[0060]

[0061] This invention first uses tin oxide, metastannic acid, and antimony oxide as the main raw materials, and calcium fluoride as the mineralizing agent. The materials are weighed and mixed according to a specific ratio, and then subjected to coarse grinding, sieving, fine grinding, drying, powdering, firing, coarse grinding, fine grinding, and drying to prepare a current-carrying compound. Then, an appropriate amount of the current-carrying compound is introduced into the insulator glaze layer, causing it to generate a certain leakage current under operating voltage, thereby generating heat. The heating performance of the glaze layer is controlled by adjusting the base glaze ratio and the amount of current-carrying compound introduced, ensuring that heating does not affect other insulator properties. The comparative data above shows that, using the difference between the product surface temperature and the ambient temperature as the evaluation criterion, the porcelain insulator prepared using the current-carrying glaze of this invention exhibits a stable temperature rise of 5℃~15℃ during thermal stability, effectively preventing icing.

[0062] The above are merely exemplary embodiments of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent exchange or substitution fall within the scope of protection of the present invention.

Claims

1. A method of preparing a current carrying glaze for porcelain insulators, characterized in that, It comprises the following steps: 1) the following weight parts of each component are mixed to obtain the carrier compound raw material: tin oxide 20-70 parts, metatitanic acid 20-70 parts, antimony oxide 5-15 parts, calcium fluoride 0.1-1 part; 2) the carrier compound raw material obtained in step 1) is firstly subjected to primary ball milling to obtain a powder with a particle size D90 of 15-25 μm, and then subjected to secondary ball milling to obtain a carrier compound powder with a particle size D50 of 0.5-0.6 μm; 3) the carrier compound powder prepared in step 2) is fired at 1250-1270 °C in an oxidizing atmosphere; 4) the carrier compound powder fired in step 3) is firstly subjected to primary ball milling to obtain a powder with a particle size D90 of 10-20 μm, and then subjected to secondary ball milling to obtain a powder with a particle size D50 of 0.5-0.6 μm, and dried to obtain the carrier compound; 5) the following weight parts of raw materials are weighed: feldspar 10-30 parts, frit 5-20 parts, quartz 10-20 parts, talc 5-10 parts, Zhangcun clay 5-15 parts, wollastonite 1-10 parts, kaolin 5-15 parts, carrier compound 20-30 parts; 6) the various raw materials in step 5) are mixed and ball milled to a particle size of ≤10 um, sieved, de-ironed, and aged for 48-72 hours to obtain the carrier glaze.

2. A method of making a porcelain insulator comprising the carrier flux of claim 1, characterized in that, It comprises the following steps: 1) the carrier glaze is adjusted to a specific gravity of 1.5-1.7 g / ml, the flow rate of the carrier glaze is measured using a four-coat viscometer, the flow rate is controlled at 12-14 seconds, the porcelain insulator body is immersed in the carrier glaze, the glazing time is 15-20 seconds, and the glaze layer thickness is controlled at 0.4-0.8 mm; 2) the porcelain insulator body with the applied glaze in step 1) is fired in a kiln, an oxidizing flame is used, the highest firing temperature is 1250-1270 °C, and the firing is divided into four stages: a low temperature stage, an oxidation and decomposition stage, a high temperature stage, and a cooling stage.

3. The method of manufacturing a porcelain insulator according to claim 2, wherein The low temperature stage is to raise the temperature to 400 °C at a temperature raising rate of 20-30 °C / h.

4. The method of claim 3, wherein the porcelain insulator is prepared by the steps of: The oxidation and decomposition stage is to raise the temperature from 400 °C to 1000 °C at a temperature raising rate of 10-15 °C / h.

5. The method of claim 4, wherein the porcelain insulator is prepared by the steps of: The high temperature stage is to raise the temperature from 1000 °C to the highest firing temperature at a temperature raising rate of 20-40 °C / h.

6. The method of claim 5, wherein the porcelain insulator is prepared by the steps of: The cooling stage is divided into two stages: a fast cooling stage and a slow cooling stage. The fast cooling stage is from the highest firing temperature to 900 °C at a temperature lowering rate of 300-500 °C / h, and the slow cooling stage is from 900 °C to room temperature at a temperature lowering rate of 30-50 °C / h.

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