An extra-high voltage direct current disc-shaped suspension porcelain insulator and a preparation method thereof

Abstract

The application discloses a UHV DC disc-shaped suspension porcelain insulator and a preparation method thereof, and the prepared insulator has good mechanical properties and electrical properties. In addition, the high-performance cement adhesive prepared by the application has the characteristics of simple stirring and construction, good fluidity, shrinkage compensation, fast strength growth, high early strength, high final strength, impact resistance, vibration resistance, iron and chloride ion free, non-toxicity, non-corrosiveness and the like, and the strength of the natural curing 3-day-old period can reach the strength index of the cement adhesive of the JB / T 4307-2004 III type, so that the compression strength characteristics of the porcelain are fully exerted, and the solidification curing time is shortened.

Description

Technical Field

[0001] This invention belongs to the field of ceramic insulator technology, specifically relating to an ultra-high voltage DC disc suspension ceramic insulator and its preparation method. Background Technology

[0002] In power transmission and distribution systems, insulators are a crucial component ensuring the safe operation of electrical equipment. Insulators primarily function to provide insulation between conductors and electrical equipment, preventing current leakage and equipment damage. Traditional insulators are typically made of materials such as glass, ceramics, or rubber, but these materials have limitations, such as low mechanical strength and poor arc resistance.

[0003] To overcome the limitations of traditional insulators, a new type of insulator, the disc suspension porcelain insulator, has emerged in recent years. Disc suspension porcelain insulators possess high mechanical strength and arc resistance, enabling stable operation under high-voltage conditions. However, existing disc suspension porcelain insulators still have some problems, such as complex manufacturing processes and high costs.

[0004] Therefore, there is a need for a method to prepare ultra-high voltage direct current disc suspension porcelain insulators that simplifies the manufacturing process, improves insulator performance, and reduces costs. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an ultra-high voltage direct current disc suspension porcelain insulator.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing an ultra-high voltage direct current disc suspension porcelain insulator, comprising,

[0009] Mix the raw materials evenly to obtain the mixed raw materials;

[0010] The mixed raw materials are wet-ball-milled;

[0011] The wet-milled mixture is sieved and iron is removed.

[0012] The mixed raw materials after iron removal by sieving are pressed to obtain mud cakes, which are then aged for 48 hours.

[0013] The mud cake is extruded in a vacuum pug mill to obtain a rough blank;

[0014] The blank is made by pressure using an aluminum mold and cloth lining, and then wet spinning and drying are used to obtain the green blank.

[0015] The process involves glazing and sanding the raw blank, firing it into a porcelain insulator, then gluing, curing, maintaining, and inspecting it to obtain a disc-shaped suspension porcelain insulator assembly.

[0016] The raw material, by weight, comprises the following components:

[0017] 10-25 parts of kaolinite-type clay, 10-25 parts of quartz-kaolinite-type clay, 20-35 parts of calcined bauxite, 15-25 parts of alumina, 10-20 parts of feldspar, 0.5-2 parts of plasticizer, 3-8 parts of nano zinc oxide, 1-3 parts of titanium dioxide, 1-3 parts of glass fiber, and 3-10 parts of modified polyimide.

[0018] As a preferred embodiment of the preparation method of the present invention, the wet-milled mixed raw materials are sieved and iron removed, wherein the sieving is a high-strength slurry sieved three times; and the iron removal is a high-strength slurry iron removal three times.

[0019] In a preferred embodiment of the preparation method described in this invention, the pressed mud has a fineness of 0.1% to 0.2% residue on a 325-mesh sieve.

[0020] As a preferred embodiment of the preparation method described in this invention, the mud cake is extruded in a vacuum plow mill, wherein the moisture difference of the mud segments fed into the plow mill is ≤0.5%, and the relative vacuum degree of the vacuum plow mill is ≥96%.

[0021] In a preferred embodiment of the preparation method described in this invention, the wet rotary blank forming process involves a forming moisture content of 17.3% to 17.8%.

[0022] In a preferred embodiment of the preparation method described in this invention, the calcination process involves a gas supply pressure of 6–7 kPa and a gas working pressure ≥1.5 kPa.

[0023] In a preferred embodiment of the preparation method described in this invention, the calcination temperature is 1200–1400°C, and the calcination time is 75 minutes. 3 Gas-fired drawer kiln, 48 hours, 180m 3 Gas-fired drawer kiln, 39 hours.

[0024] As a preferred embodiment of the preparation method described in this invention, the curing process involves pre-curing with a suspended chain and ensuring hardening curing upon immersion in water.

[0025] Another objective of this invention is to overcome the shortcomings of the prior art and provide an ultra-high voltage direct current disc suspension porcelain insulator, characterized in that: the insulator is divided into two parts: a head and a skirt, the head being formed by bonding a porcelain head, an iron cap, and a steel foot of a porcelain piece together with a cement adhesive.

[0026] As a preferred embodiment of the UHVDC disc suspension porcelain insulator of the present invention, the raw materials of the cement adhesive include the following components by weight percentage: 40-60 wt% silicate cement, 30-60 wt% porcelain sand, 1-3 wt% additives, and 15-20 wt% water.

[0027] Beneficial effects of this invention:

[0028] The cement binder used in this invention is ordinary silicate cement with low autoclaving expansion rate and a self-developed additive formula, which ensures that the compressive strength, drying shrinkage rate and water absorption rate are within the strictly controlled standard range.

[0029] The high-performance cementitious adhesive prepared by this invention features simple mixing and application; good fluidity; shrinkage compensation; rapid strength gain, high early strength, and high final strength; impact resistance and vibration resistance; absence of iron and chloride ions; and non-toxicity and non-corrosiveness. Its strength after 3 days of natural curing reaches the strength index of Class III cementitious adhesives in JB / T4307-2004. This ensures the full utilization of the compressive strength characteristics of porcelain and also shortens the curing time.

[0030] The ultra-high voltage DC disc suspension porcelain insulator prepared by this invention has good mechanical properties, electrical properties and corona resistance. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0034] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0035] The modified polyimide preparation method in this invention is as follows: the polyimide is hydrolyzed in potassium hydroxide solution for 30 min, then washed with water until neutral, and then reacted with aluminum chloride solution for 3-5 h to obtain the modified polyimide.

[0036] Performance testing methods:

[0037] Volume resistivity: Refer to GB / T5594.5-1995 "Test Methods for Performance of Structural Ceramic Materials for Electronic Components - Volume Resistivity Test Method".

[0038] Bending strength: Refer to GB / T6569-2006 "Test method for bending strength of fine ceramics".

[0039] Example 1

[0040] This embodiment describes the preparation of a cementitious adhesive, including the following steps:

[0041] (1) Weigh out the corresponding masses of each raw material according to the following mass percentage ratios, and set aside:

[0042] 45 wt% silicate cement, 35 wt% artificial ceramic sand.

[0043] (2) Mix the above-weighed 45wt% silicate cement and 35wt% artificial ceramic sand to obtain the base material;

[0044] (3) Add 1.2wt% polycarboxylate compound water-reducing agent, 0.3wt% polypropylene fiber as crack-resistant agent, 0.2wt% defoamer, and 0.3wt% leveling agent of the total weight of the base material, mix well; then add 18wt% water of the total weight of the base material and stir well to obtain cement adhesive.

[0045] Example 2

[0046] This embodiment describes the preparation of an ultra-high voltage direct current disc-shaped suspension porcelain insulator, including the following steps:

[0047] (1) Mix the raw materials evenly to obtain the mixed raw materials:

[0048] 20 parts of kaolinite-type clay, 20 parts of quartz-kaolinite-type clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 0.5 parts of plasticizer, 6 parts of nano zinc oxide, 2 parts of titanium dioxide, 1.5 parts of glass fiber, and 5 parts of modified polyimide.

[0049] (2) Wet ball milling of the mixed raw materials:

[0050] Use a two-stage feeding wet ball mill;

[0051] (3) The wet-milled mixture is sieved and iron is removed:

[0052] The system uses a 1-stage 250-mesh sieve connected in series with a 3-stage sieve (280 mesh / inch), and a 1-stage electromagnetic separator connected in series with a 2-stage permanent magnet (9000-10000Gs) strong magnetic field for automatic iron removal.

[0053] (4) The mixed raw materials after iron removal by sieving are pressed to obtain mud cake and aged for 48 hours:

[0054] Use a hydraulic nylon plate filter press to press the mud (the mud fineness is 0.1% to 0.2% residue on a 325-mesh sieve);

[0055] (5) The mud cake is extruded in a vacuum plowing machine to obtain a rough blank:

[0056] use Vacuum pumice extrusion blanks are produced by a vacuum pumice extrusion machine. The vacuum pumice machine is equipped with a liquid ring vacuum pump, with a single pump per machine and a relative vacuum degree of ≥96%.

[0057] (6) Using aluminum mold cloth lining pressure to make blanks, wet spinning blanks are formed and dried to obtain green blanks:

[0058] The blank is made using pressure with an aluminum mold and cloth lining, then shaped by a template cutter (forming moisture content 17.3%–17.8%), wet trimming, and drying in an intermittent dryer.

[0059] (7) After glazing, sanding, firing, gluing, curing, maintaining, and inspecting the green body, a disc-shaped suspension porcelain insulator is obtained:

[0060] After each blank is inspected, mechanical glazing is applied, and the blanks are fired in a gas-fired drawer kiln (firing time, temperature, atmosphere, and pressure curves are executed and automatically recorded). Each piece of porcelain is inspected, and each piece of porcelain with a pressure rating of 160kN or higher undergoes an internal water pressure test.

[0061] The cement adhesive prepared in Example 1 was used;

[0062] The ceramic cap is glued, and an automatic glue-gluing line is used to ensure concentric tooling and to ensure that the center of the iron cap and the ceramic part are basically aligned.

[0063] Pre-curing with suspended chains and ensuring hardening curing in water are adopted;

[0064] Each product undergoes high-frequency and power-frequency electrical testing; sampling tests are conducted; and products are packaged and delivered after passing inspection.

[0065] Example 3

[0066] The difference between this embodiment and embodiment 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 1.5 parts of plasticizer, 6 parts of nano zinc oxide, 1 part of titanium dioxide, 1.5 parts of glass fiber, and 5 parts of modified polyimide; the remaining steps are the same as in embodiment 2.

[0067] Example 4

[0068] The difference between this embodiment and embodiment 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 0.5 parts of plasticizer, 5 parts of nano zinc oxide, 2 parts of titanium dioxide, 2.5 parts of glass fiber, and 5 parts of modified polyimide; the remaining steps are the same as in embodiment 2.

[0069] Example 5

[0070] The difference between this embodiment and embodiment 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 0.5 parts of plasticizer, 4 parts of nano zinc oxide, 3 parts of titanium dioxide, 2.5 parts of glass fiber, and 5 parts of modified polyimide; the remaining steps are the same as in embodiment 2.

[0071] Example 6

[0072] The difference between this embodiment and embodiment 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 1.5 parts of plasticizer, 4 parts of nano zinc oxide, 3 parts of titanium dioxide, 1.5 parts of glass fiber, and 5 parts of modified polyimide; the remaining steps are the same as in embodiment 2.

[0073] Example 7

[0074] The difference between this embodiment and embodiment 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 1.5 parts of plasticizer, 5 parts of nano zinc oxide, 2 parts of titanium dioxide, 1.5 parts of glass fiber, and 5 parts of modified polyimide; the remaining steps are the same as in embodiment 2.

[0075] Comparative Example 1

[0076] The difference between this comparative example and Example 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 3 parts of plasticizer, 6 parts of nano zinc oxide, 1 part of titanium dioxide, and 5 parts of modified polyimide; the remaining steps are the same as in Example 2.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 6 parts of nano zinc oxide, 1 part of titanium dioxide, 3 parts of glass fiber, and 5 parts of modified polyimide; the remaining steps are the same as in Example 2.

[0079] Comparative Example 3

[0080] The difference between this comparative example and Example 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 0.5 parts of plasticizer, 7 parts of nano zinc oxide, 2.5 parts of glass fiber, and 5 parts of modified polyimide; the remaining steps are the same as in Example 2.

[0081] Comparative Example 4

[0082] The difference between this comparative example and Example 2 is that the mixed raw material components in step (1) are: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 1.5 parts of plasticizer, 7 parts of titanium dioxide, 1.5 parts of glass fiber, and 5 parts of modified polyimide; the remaining steps are the same as in Example 2.

[0083] Comparative Example 5

[0084] The difference between this comparative example and Example 1 is that the components in step (3) are replaced with: 0.2 wt% polycarboxylate compound water-reducing agent, 0.3 wt% polypropylene fiber as crack-resistant agent, 0.2 wt% defoamer, and 0.3 wt% leveling agent, all added according to the total weight of the base material, and mixed well; then 19 wt% water according to the total weight of the base material is added and stirred well to obtain the cement adhesive; the remaining steps are the same as in Example 1 to obtain the cement adhesive.

[0085] Comparative Example 6

[0086] The difference between this comparative example and Example 1 is that the components in step (3) are replaced with: 1.2 wt% polycarboxylate compound water-reducing agent, 1.3 wt% polypropylene fiber as crack-resistant agent, 0.2 wt% defoamer, and 0.3 wt% leveling agent, all added according to the total weight of the base material, and mixed well; then 17 wt% water according to the total weight of the base material is added and stirred well to obtain the cement adhesive; the remaining steps are the same as in Example 1 to obtain the cement adhesive.

[0087] Comparative Example 7

[0088] The difference between this comparative example and Example 2 is that the cement adhesive used in step (7) is the cement adhesive prepared in Comparative Example 5.

[0089] Comparative Example 8

[0090] The difference between this comparative example and Example 2 is that the cement adhesive used in step (7) is the cement adhesive prepared in Comparative Example 6.

[0091] The performance of the insulators prepared in Examples 2-7, Comparative Examples 1-4, and Comparative Examples 7 and 8 was tested, and the test results are shown in Table 1.

[0092] Table 1 Insulator performance test results

[0093] Volume resistivity (Ω·cm) Bending strength (MPa) Example 2 <![CDATA[4.2×10 18 ]]> 247 Example 3 <![CDATA[4.1×10 18 ]]> 251 Example 4 <![CDATA[3.9×10 18 ]]> 241 Example 5 <![CDATA[4.4×10 18 ]]> 261 Example 6 <![CDATA[3.8×10 18 ]]> 245 Example 7 <![CDATA[4.2×10 18 ]]> 253 Comparative Example 1 <![CDATA[2.6×10 18 ]]> 176 Comparative Example 2 <![CDATA[2.4×10 18 ]]> 198 Comparative Example 3 <![CDATA[2.5×10 18 ]]> 201 Comparative Example 4 <![CDATA[1.6×10 18 ]]> 207 Comparative Example 7 <![CDATA[2.3×10 18 ]]> 204 Comparative Example 8 <![CDATA[3.1×10 18 ]]> 205

[0094] As shown in Table 1, the insulators prepared in the examples have high volume resistivity, high flexural strength, and excellent electrical and mechanical properties. Examples 2-7 and Comparative Examples 1-4 show that the insulators prepared without glass fiber, plasticizer, nano-zinc oxide, and titanium dioxide exhibit poorer performance. This is because glass fiber and plasticizer, and nano-zinc oxide and titanium dioxide, have a synergistic effect; their synergistic use can improve the performance of the insulators.

[0095] Comparative Example 9

[0096] The difference between this comparative example and Example 2 is that the components in step (3) are replaced with: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 0.5 parts of plasticizer, 6 parts of nano zinc oxide, 2 parts of titanium dioxide, 1.5 parts of glass fiber, and 3 parts of unmodified polyimide. The remaining steps are the same as in Example 2.

[0097] Comparative Example 10

[0098] The difference between this comparative example and Example 2 is that the components in step (3) are replaced with: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 0.5 parts of plasticizer, 6 parts of nano zinc oxide, 2 parts of titanium dioxide, 1.5 parts of glass fiber, and 3 parts of modified polyimide. The remaining steps are the same as in Example 2.

[0099] Comparative Example 11

[0100] The difference between this comparative example and Example 2 is that the components in step (3) are replaced with: 20 parts of kaolinite clay, 20 parts of quartz plus kaolinite clay, 20 parts of calcined bauxite, 15 parts of alumina, 15 parts of feldspar, 0.5 parts of plasticizer, 6 parts of nano zinc oxide, 2 parts of titanium dioxide, 1.5 parts of glass fiber, and 15 parts of modified polyimide. The remaining steps are the same as in Example 2, but because the amount of modified polyimide added is large, the curing time is longer, which affects the production cycle.

[0101] The materials prepared in Example 2 and Comparative Examples 9 and 10 were subjected to electrical resistance tests using a high-frequency pulse voltage tester. The test method was in accordance with the national standard GB / T 22689-2008. The test results are shown in Table 2.

[0102] Table 2 Results of Corona Resistance Test

[0103] Corona resistance time (min) Example 2 164 Comparative Example 9 56 Comparative Example 10 89

[0104] As can be seen from Table 2, the porcelain insulator prepared in Example 2 has a longer corona resistance time and exhibits excellent corona resistance performance.

[0105] 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 it. 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 spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A method for preparing an ultra-high voltage direct current disc suspension porcelain insulator, characterized in that: include, The raw materials are mixed evenly to obtain a mixed raw material, which is then wet-milled. The wet-milled mixture is sieved and iron is removed. The mixed raw materials after iron removal by sieving are pressed to obtain mud cakes, which are then aged for 48 hours. The mud cake is extruded in a vacuum pug mill to obtain a rough blank; The blank is made by pressure using an aluminum mold and cloth lining, and then wet spinning and drying are used to obtain the green blank. The process involves glazing and sanding the raw blank, firing it into a porcelain insulator, then gluing, curing, maintaining, and inspecting it to obtain a disc-shaped suspension porcelain insulator assembly. The raw material, by weight, comprises the following components: 10-25 parts of kaolinite-type clay, 10-25 parts of quartz-kaolinite-type clay, 20-35 parts of calcined bauxite, 15-25 parts of alumina, 10-20 parts of feldspar, 0.5-2 parts of plasticizer, 3-8 parts of nano zinc oxide, 1-3 parts of titanium dioxide, 1-3 parts of glass fiber, and 5-10 parts of modified polyimide; The wet rotary blank forming process involves a forming moisture content of 17.3% to 17.8%. The maintenance process involves pre-curing with a suspended chain and ensuring hardening curing upon immersion in water. The insulator is divided into two parts: the head and the skirt. The head is made of porcelain head, iron cap and steel foot of porcelain piece bonded together with cement adhesive. The raw materials of the cement adhesive, each component according to the percentage of total mass, include the following components: 40-60 wt% silicate cement, 30-60 wt% porcelain sand, 1-3 wt% additives and 15-20 wt% water.

2. The preparation method according to claim 1, characterized in that: The process involves sieving and removing iron from the wet-milled mixed raw materials, wherein the sieving is performed four times for the high-strength slurry; and the iron removal is performed four times for the high-strength slurry.

3. The preparation method according to claim 1, characterized in that: The pressed mud has a fineness of 0.1% to 0.2% residue on a 325-mesh sieve.

4. The preparation method according to claim 1, characterized in that: The mud cake is extruded in a vacuum plowing machine, wherein the moisture difference of the mud segments fed into the plowing machine is ≤0.5%, and the relative vacuum degree of the vacuum plowing machine is ≥96%.

5. The preparation method according to claim 1, characterized in that: In the calcination process, the gas supply pressure is 6-7 kPa, and the gas working pressure is ≥1.5 kPa.

6. The preparation method according to claim 1, characterized in that: The calcination temperature is 1200~1400℃, and the calcination time is 48h for a 75m³ gas-fired drawer kiln and 39h for a 180m³ gas-fired drawer kiln.