High-strength electric porcelain and preparation method and application thereof

Abstract

This invention provides a high-strength electrical porcelain, its preparation method, and its application, relating to the field of electrical porcelain technology. The high-strength electrical porcelain includes a base glaze and a coating; the base glaze comprises the following chemical raw materials in parts by weight: 50 parts α-Al 2 O 3 16-20 parts SiO 2 3-7 parts CaO, 1-3 parts MgO, 2-5 parts K 2 O, 0.5~2.8 parts Na 2 O, 3 to 7 parts ZrO 2 2-6 parts TiO 2 The coating comprises the following chemical raw materials in parts by weight: 50 parts γ-Al 2 O 3 25-33 copies of Y 2 O 3 2-4 parts MoSi 2 and 7-15 parts α-Si 3 N 4 The preparation method of high-strength electrical porcelain includes the following steps: S1. Preparation of base glaze slurry; S2. Base glaze treatment; S3. Preparation of coating powder; S4. Coating treatment. The high-strength electrical porcelain of the present invention has high strength, excellent heat resistance, and excellent corrosion resistance.

Description

A high-strength electrical porcelain, its preparation method and application Technical Field

[0001] This invention belongs to the field of electrical porcelain technology, specifically a high-strength electrical porcelain, its preparation method, and its application. Background Technology

[0002] Current research on ultra-high voltage electrical porcelain mainly focuses on using high-alumina ceramics as the base material and improving the overall performance of the porcelain by adjusting the inorganic raw material formula. However, due to the compatibility issues between chemical raw materials and the complexity of interactions between multiple raw materials, the formula development process faces significant challenges.

[0003] Existing conventional electrical porcelains have many shortcomings, such as insufficient surface strength, poor heat resistance, and weak corrosion resistance. These characteristics limit their application in harsh environments. To overcome these problems, it is particularly important to develop an electrical porcelain that possesses both high strength and good heat resistance and corrosion resistance.

[0004] This invention proposes a novel solution that significantly improves the surface properties of electrical porcelain while effectively enhancing its heat resistance and corrosion resistance. These characteristics enable the electrical porcelain products of this invention to maintain their structural and functional integrity under extreme temperature variations and harsh corrosive environments, meeting the high standards required for electrical porcelain materials in ultra-high voltage power equipment, thereby broadening the application range of electrical porcelain in complex environments. Summary of the Invention

[0005] This invention overcomes at least one of the following shortcomings in existing electrical porcelain: insufficient surface strength, poor heat resistance, and weak corrosion resistance. Therefore, it provides a high-strength electrical porcelain, its preparation method, and its application. This high-strength electrical porcelain exhibits high strength, excellent heat resistance, and excellent corrosion resistance.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] This invention provides a high-strength electrical porcelain, comprising a base glaze and a coating;

[0008] The base glaze comprises the following chemical raw materials in parts by weight: 50 parts α-Al2O3, 16-20 parts SiO2, 3-7 parts CaO, 1-3 parts MgO, 2-5 parts K2O, 0.5-2.8 parts Na2O, 3-7 parts ZrO2, and 2-6 parts TiO2;

[0009] The coating comprises the following chemical raw materials in parts by weight: 50 parts γ-Al2O3, 25-33 parts Y2O3, 2-4 parts MoSi2 and 7-15 parts α-Si3N4.

[0010] Furthermore, the base glaze comprises the following chemical raw materials in parts by weight: 50 parts α-Al2O3, 17.3-19.4 parts SiO2, 3.3-6.5 parts CaO, 1.58-2.7 parts MgO, 2.45-4.56 parts K2O, 0.62-2.31 parts Na2O, 3.4-6.6 parts ZrO2, and 2.7-5.6 parts TiO2.

[0011] Furthermore, the coating comprises the following chemical raw materials in parts by weight: 50 parts γ-Al2O3, 26-31 parts Y2O3, 2.2-3.8 parts MoSi2 and 7.9-13.5 parts α-Si3N4.

[0012] In this invention, γ-Al2O3 is selected for its good compatibility with the base glaze and excellent dispersion and adhesion. On the other hand, γ-Al2O3 can be stably converted into α-Al2O3 with better thermal stability at high temperatures. Y2O3 has good chemical inertness, corrosion resistance and wear resistance, and MoSi2 has excellent high-temperature oxidation resistance. The addition of both can enable the electric porcelain to be used in extreme environments, but both have high coefficients of thermal expansion and usually cannot be directly applied to the ceramic matrix. α-Si3N4 has a low coefficient of thermal expansion, which not only helps to reduce the overall thermal expansion of the material, but also can further enhance the overall performance of the material by controlling its grain growth and refinement.

[0013] In this invention, the particle size of the α-Al2O3 (CAS No.: 1344-28-1) is 0.2 to 0.4 μm.

[0014] In this invention, the particle size of the γ-Al2O3 is ≤50nm.

[0015] In this invention, the particle size of the α-Si3N4 (CAS No.: 12033-89-5) is 10-50 nm, for example 20 nm.

[0016] In this invention, the thickness of the base glaze is 0.3 to 0.45 mm, preferably 0.35 to 0.4 mm.

[0017] In this invention, the thickness of the coating is 0.2 to 0.3 mm; preferably 0.22 to 0.26 mm.

[0018] In this invention, the coefficient of thermal expansion of the base glaze is 5.05 to 5.18 × 10⁻⁶. -6 / K, preferably 5.11~5.13×10 -6 / K.

[0019] In this invention, the coefficient of thermal expansion of the coating is 5.21 to 5.28 × 10⁻⁶. -6 / K.

[0020] In this invention, the thermal shock resistance temperature of the high-strength electrical porcelain is 250-270℃.

[0021] In this invention, the bending strength of the high-strength electrical porcelain is 485-497 MPa.

[0022] The present invention also provides a method for preparing the above-mentioned high-strength electrical porcelain, comprising the following steps:

[0023] S1. Preparation of base glaze slurry: After mixing the chemical raw materials of the base glaze according to the above formula, they are ball-milled, sieved and mixed to obtain the base glaze slurry;

[0024] S2. Base glaze treatment: The body is immersed in the base glaze slurry and then sintered to obtain a base glaze body;

[0025] The sintering temperature is set at 1050–1150°C, and more preferably at 1070–1130°C.

[0026] The surface roughness Ra of the base glaze body is 28–43 μm;

[0027] S3. Coating powder preparation: Prepare the chemical raw materials for coating according to the above formula, and then grind and sieve them to obtain the coating powder;

[0028] S4. Coating treatment: High-strength electrical porcelain can be obtained by atmospheric plasma spraying of coating powder on the surface of the base glaze body.

[0029] In S1, the mesh size of the sieve is 250 to 300 mesh.

[0030] In S1, the specific gravity of the glaze slurry is 1.45–1.47 g / cm³. 3 .

[0031] In step S2, the base glaze blank also needs to undergo cleaning, polishing, and sandblasting processes to achieve a surface roughness Ra of 28–43 μm, preferably 30–43 μm. The surface roughness of the base glaze blank has a significant impact on the adhesion and growth of the coating. If the base glaze surface is too smooth, the bonding force between the coating and the base glaze will be weakened, resulting in poor coating adhesion. Conversely, if the surface roughness is too high, the growth of the coating may become uneven, affecting the overall quality and performance of the coating.

[0032] In S2, the heating rate of the sintering is 15-30°C / min.

[0033] In S2, the holding time for sintering is 6 to 10 hours.

[0034] In S3, the mesh size of the sieve is 500 to 800 mesh.

[0035] In S4, the argon gas flow rate for atmospheric plasma spraying is 30–40 L / min. -1 .

[0036] In S4, the hydrogen flow rate for the atmospheric plasma spraying is 3–7 L·min. -1 .

[0037] In step S4, the current setting for atmospheric plasma spraying is 350–380 A. Setting the current too high may cause the coating to become overly dense, reducing porosity and potentially increasing its brittleness and reducing its toughness. Conversely, setting the current too low may result in increased porosity, affecting the coating's density and overall strength.

[0038] In step S4, the atmospheric plasma spraying is followed by heat treatment at 1100–1200°C for 15–24 hours. While excessively high heat treatment can lead to rapid coating growth, localized stress concentration may increase porosity and potentially cause cracking.

[0039] The present invention also provides the application of the aforementioned high-strength electrical porcelain in high-voltage transmission lines, substations and converter stations, aerospace, chemical and petroleum industries, or marine and offshore facilities.

[0040] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] 1. This invention ensures excellent adhesion between the base glaze and the coating by adjusting the formulations of the base glaze and the coating, while simultaneously exploring a reasonable range for the surface roughness of the base glaze body. This optimization not only improves the surface quality of the electrical porcelain but also enhances its overall performance.

[0043] 2. This invention explores the influence of atmospheric plasma spraying process on coating growth and successfully prepares electrical porcelain with high strength, excellent thermal shock resistance and salt spray corrosion resistance by precisely controlling the spraying parameters. Detailed Implementation

[0044] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0045] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0046] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is understood that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this invention, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein; "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer greater than or equal to 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0048] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0049] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0050] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0051] Unless otherwise specified, the term "or" is inclusive in this invention. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0052] Detailed information on the chemical raw materials used in the following examples and comparative examples is shown in Table 1;

[0053] Table 1

[0054] Chemical raw materials CAS number, manufacturer, model or specification: α-Si3N412033-89-5 Guangzhou Wengjiang, particle size 20nm; α-Al2O31344-28-1 Beijing Puxitang, particle size 0.2~0.4μm; γ-Al2O31344-28-1 Beijing Puxitang, particle size 20nm. surface

[0055] Example 1

[0056] 1. The high-strength electrical porcelain of this embodiment includes a base glaze and a coating:

[0057] The base glaze is composed of the following chemical raw materials in parts by weight: 50 parts α-Al2O3, 17.8 parts SiO2, 4.7 parts CaO, 1.58 parts MgO, 4.56 parts K2O, 0.62 parts Na2O, 5.22 parts ZrO2, and 3.9 parts TiO2.

[0058] The coating is composed of the following chemical raw materials in parts by weight: 50 parts γ-Al2O3, 27.4 parts Y2O3, 2.6 parts MoSi2 and 10.1 parts α-Si3N4.

[0059] The thickness of the base glaze is 0.37 mm, and the thickness of the coating is 0.25 mm.

[0060] 2. The preparation method of the high-strength electrical porcelain in this embodiment is as follows:

[0061] S1. Preparation of the base glaze slurry: After preparing the chemical raw materials for the base glaze according to the above formula, they are ball-milled, passed through a 250-mesh sieve, and adjusted to obtain the base glaze slurry. The specific gravity of the slurry is 1.46 g / cm³. 3 ;

[0062] S2. Base glaze treatment: The body is immersed in the base glaze slurry and then sintered to obtain a base glaze body;

[0063] The sintering temperature is set at 1100℃, the sintering heating rate is 15℃ / min, and the temperature is held at 1100℃ for 8 hours.

[0064] The base glaze body is cleaned, polished and sandblasted to make its surface roughness Ra 34μm;

[0065] S3. Coating Powder Preparation: Prepare the chemical raw materials for the coating according to the above formula, then grind and pass through a 600-mesh sieve to obtain the coating powder;

[0066] S4. Coating treatment: The coating powder is applied to the surface of the base glaze blank by atmospheric plasma spraying with an argon flow rate of 35 L·min. -1 The hydrogen flow rate is 5 L / min. -1 Set the current value to 375A, and after spraying, keep it at 1100℃ for 20 hours to obtain a high-strength electrical porcelain.

[0067] Example 2

[0068] The difference between this embodiment and Embodiment 1 is as follows:

[0069] 1. The high-strength electrical porcelain of this embodiment includes a base glaze and a coating:

[0070] The base glaze is composed of the following chemical raw materials in parts by weight: 50 parts α-Al2O3, 19.4 parts SiO2, 3.3 parts CaO, 2.3 parts MgO, 2.58 parts K2O, 2.3 parts Na2O, 6.1 parts ZrO2, and 2.7 parts TiO2.

[0071] The coating is composed of the following chemical raw materials in parts by weight: 50 parts γ-Al2O3, 29 parts Y2O3, 3.3 parts MoSi2 and 13.5 parts α-Si3N4.

[0072] The thickness of the base glaze is 0.35 mm, and the thickness of the coating is 0.22 mm.

[0073] Example 3

[0074] The difference between this embodiment and Embodiment 1 is as follows:

[0075] 2. The preparation method of the high-strength electrical porcelain in this embodiment is as follows:

[0076] In S2, the base glaze body is cleaned, polished, and sandblasted to achieve a surface roughness Ra of 30μm.

[0077] In S4, the set current value for atmospheric plasma spraying is 380A, and the atmospheric plasma spraying is kept at 1150℃ for 18 hours.

[0078] Example 4

[0079] The difference between this embodiment and Embodiment 1 is as follows:

[0080] 2. The preparation method of the high-strength electrical porcelain in this embodiment is as follows:

[0081] In S2, the base glaze body is cleaned, polished, and sandblasted to achieve a surface roughness Ra of 43 μm.

[0082] In S4, the set current value for atmospheric plasma spraying is 350A, and the atmospheric plasma spraying is kept at 1100℃ for 24 hours.

[0083] Comparative Example 1

[0084] The difference between this comparative example and Example 1 is as follows:

[0085] 1. The high-strength electrical porcelain of this comparative example includes a base glaze and a coating:

[0086] The coating is composed of the following chemical raw materials in parts by weight: 50 parts γ-Al2O3, 30.5 parts Y2O3, 9.7 parts MoSi2 and 6.4 parts α-Si3N4.

[0087] The high-strength electrical porcelain prepared in this comparative example has multiple cracks and bulges on its surface.

[0088] Comparative Example 2

[0089] The difference between this comparative example and Example 1 is as follows:

[0090] 1. The high-strength electrical porcelain of this comparative example includes a base glaze and a coating:

[0091] The coating is composed of the following chemical raw materials in parts by weight: 50 parts γ-Al2O3, 26 parts Y2O3, 0 parts MoSi2 and 9.7 parts α-Si3N4.

[0092] The high-strength electrical porcelain prepared in this comparative example has an uneven surface, exhibiting multiple bumps and depressions.

[0093] Comparative Example 3

[0094] The difference between this comparative example and Example 1 is as follows:

[0095] 2. The preparation method of the high-strength electrical porcelain in this embodiment is as follows:

[0096] In S2, the surface roughness Ra of the base glaze body is 25 μm.

[0097] The high-strength electrical porcelain prepared in this comparative example has slight bulging on its surface.

[0098] Comparative Example 4

[0099] The difference between this embodiment and Embodiment 1 is as follows:

[0100] 2. The preparation method of the high-strength electrical porcelain in this embodiment is as follows:

[0101] In S4, the set current value for atmospheric plasma spraying is 300A, and the atmospheric plasma spraying is kept at 1300℃ for 10 hours.

[0102] The high-strength electrical porcelain prepared in this comparative example has a small number of relatively wide cracks on its surface (the width is between 0.08 and 0.17 mm).

[0103] Effect Example

[0104] Performance tests were conducted on the above embodiments and comparative examples, as shown in Table 2.

[0105] Thermal stability test method: Refer to GB / T 3298-2022 Test method for thermal shock resistance of daily ceramics. According to the test procedure of the national standard, the temperature is usually gradually increased in 20℃ intervals. In order to improve the accuracy of the test, the temperature is actually gradually increased in 10℃ intervals. The thermal shock resistance temperature in the table below refers to the thermal shock resistance temperature before cracks appear.

[0106] Thermal expansion coefficient test method: Refer to GB / T 3810.8-2016 Ceramic Tile Test Methods Part 8: Determination of linear thermal expansion, and test the surface of the base glaze body obtained in S2 and the high-strength electrical porcelain obtained in S4 after peeling.

[0107] Method for determining flexural strength: GB / T 6569 Test method for flexural strength of fine ceramics, three-point flexural method.

[0108] Salt spray resistance test method: Refer to GB / T 10125-2021 Artificial atmosphere corrosion test salt spray test (neutral salt spray test), test time 800h.

[0109] Table 2

[0110]

[0111]

[0112] Table 2 shows that Comparative Example 1 has a higher MoSi2 content but a lower α-Si3N4 content in its coating. This higher coefficient of thermal expansion leads to compressive stress, resulting in poor surface quality of the porcelain, including unevenness, multiple cracks and bulges, and significant peeling after salt spray testing. Comparative Example 2, lacking MoSi2, exhibits poor corrosion resistance and severe surface powdering. Comparative Example 3 has a low surface roughness in its base glaze, resulting in poor adhesion between the coating and the base glaze. This leads to slight bulging on the surface of the high-strength porcelain, and further increases in surface cracks and bulges after salt spray testing. Comparative Example 4 suffers from an excessively low atmospheric ion spraying current and a high insulation temperature, resulting in numerous pores in the coating and excessively rapid coating growth, causing localized stress concentration and further inducing cracking.

[0113] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this invention. It should be understood that the above descriptions are merely specific embodiments of this invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A high-strength electrical porcelain, characterized in that, The product includes a base glaze and a coating; the base glaze comprises the following chemical raw materials in parts by weight: 50 parts α-Al2O3, 16-20 parts SiO2, 3-7 parts CaO, 1-3 parts MgO, 2-5 parts K2O, 0.5-2.8 parts Na2O, 3-7 parts ZrO2, and 2-6 parts TiO2; the coating comprises the following chemical raw materials in parts by weight: 50 parts γ-Al2O3, 25-33 parts Y2O3, 2-4 parts MoSi2, and 7-15 parts α-Si3N4.

2. The high-strength electrical porcelain as described in claim 1, characterized in that, The following conditions (1) to (2) must be met: (1) The base glaze contains the following chemical raw materials in parts by weight: 50 parts α-Al2O3, 17.3 to 19.4 parts SiO2, 3.3 to 6.5 parts CaO, 1.58 to 2.7 parts MgO, 2.45 to 4.56 parts K2O, 0.62 to 2.31 parts Na2O, 3.4 to 6.6 parts ZrO2, and 2.7 to 5.6 parts TiO2; (2) The coating contains the following chemical raw materials in parts by weight: 50 parts γ-Al2O3, 26 to 31 parts Y2O3, 2.2 to 3.8 parts MoSi2 and 7.9 to 13.5 parts α-Si3N4.

3. The high-strength electrical porcelain as described in claim 1, characterized in that, The chemical raw materials satisfy at least one of the following conditions (1) to (3): (1) The particle size of the α-Al2O3 is 0.2 to 0.4 μm; (2) The particle size of the γ-Al2O3 is ≤50 nm; (3) The particle size of the α-Si3N4 is 10 to 50 nm.

4. The high-strength electrical porcelain as described in claim 1, characterized in that, The following conditions (1) to (2) must be met: (1) the thickness of the base glaze is 0.30 to 0.45 mm; (2) the thickness of the coating is 0.2 to 0.3 mm.

5. The high-strength electrical porcelain as described in claim 1, characterized in that, The following conditions (1) to (2) must be met: (1) The coefficient of thermal expansion of the base glaze is 5.05 to 5.18 × 10⁻⁶. -6 / K; (2) The coefficient of thermal expansion of the coating is 5.21~5.28×10 -6 / K.

6. The high-strength electrical porcelain as described in claim 1, characterized in that, The high-strength electrical porcelain must meet at least one of the following conditions (1) to (2): (1) the thermal shock resistance temperature of the high-strength electrical porcelain is 250 to 270°C; (2) the bending strength of the high-strength electrical porcelain is 485 to 497 MPa.

7. The method for preparing high-strength electrical porcelain according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Preparation of base glaze slurry: After mixing the chemical raw materials of the base glaze according to the above formula, they are ball-milled, sieved and mixed to obtain the base glaze slurry; S2. Base glaze treatment: The body is immersed in the base glaze slurry and then sintered to obtain a base glaze body; the sintering temperature is set at 1050~1150℃; the surface roughness Ra of the base glaze body is 28~43μm; S3. Coating powder preparation: Prepare the chemical raw materials for coating according to the above formula, and then grind and sieve them to obtain the coating powder; S4. Coating treatment: High-strength electrical porcelain can be obtained by atmospheric plasma spraying of coating powder on the surface of the base glaze body.

8. The method for preparing high-strength electrical porcelain as described in claim 7, characterized in that, The following conditions (1) to (5) must be met: (1) In S1, the mesh size of the sieve is 250 to 300 mesh; (2) In S1, the specific gravity of the glaze slurry is 1.45 to 1.47 g / cm³. 3 (3) In S2, the heating rate of the sintering is 15-30℃ / min; (4) In S2, the holding time of the sintering is 6-10h; (5) In S3, the mesh size of the sieve is 500-800 mesh.

9. The method for preparing high-strength electrical porcelain as described in claim 7, characterized in that, The atmospheric plasma spraying satisfies at least one of the following conditions (1) to (4): (1) The argon flow rate of the atmospheric plasma spraying is 30 to 40 L·min. -1 (2) The hydrogen flow rate for atmospheric plasma spraying is 3-7 L / min. -1 (3) The set current value of the atmospheric plasma spraying is 350-380A; (4) After the atmospheric plasma spraying, it is kept at 1100-1200℃ for 15-24h.

10. The application of the high-strength electrical porcelain as described in claims 1 to 6 in high-voltage transmission lines, substations and converter stations, aerospace, chemical and petroleum industries, or marine and offshore facilities.

Images