Alumina ceramic glaze based on daily ceramic waste and its preparation method and application

Abstract

The present invention relates to the field of ceramic technology, and discloses an alumina ceramic glaze based on daily ceramic waste, its preparation method, and application. The alumina ceramic glaze comprises the following raw materials in parts by weight: 28-42 parts of daily ceramic waste, 25-30 parts of kaolin, 6-12 parts of calcined talc, 3-7 parts of borax, 6-14 parts of alumina, 3-5 parts of zirconium oxide, 1-3 parts of lanthanum oxide, and 3-6 parts of self-repairing particles; the self-repairing particles include mesoporous alumina doped with Si and Zr and V2O5-B2O3-TeO2-based glass with a softening point of 200-300°C that fills the pores of the mesoporous alumina. After the glaze of the present invention is applied to the surface of the alumina ceramic to form a glaze layer, it can effectively improve the insulation of the alumina ceramic, while also ensuring a high bonding stability between the glaze layer and the alumina ceramic, thereby avoiding the problem of a significant decrease in insulation and cracking of the glaze layer during thermal cycling.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramics, and in particular to an alumina ceramic glaze based on daily ceramic waste, and a preparation method and application thereof. Background Art

[0002] Alumina ceramics are high-performance ceramic materials with α-Al2O3 as the main crystalline phase. Due to their high strength, high-temperature resistance, corrosion resistance, and excellent electrical insulation, they are widely used in fields such as insulation components for power equipment, vacuum interrupters, and circuit substrates. However, surface defects such as microcracks, pores, and grain boundaries can easily lead to environmental medium penetration, charge accumulation, and chemical corrosion, which in turn can cause surface discharge, leakage, and even insulation failure, severely limiting their long-term reliability under extreme operating conditions such as high voltage, high humidity, and severe corrosion. These problems are expected to be resolved by constructing a coating on the surface of alumina ceramics that can improve surface properties through physical sealing and electric field regulation.

[0003] At present, the main method to improve the surface properties of alumina ceramics is to apply a coating through chemical vapor deposition or plasma spraying. Among them, the chemical vapor deposition method can improve the surface hardness by depositing a thin film of AlN, SiC, etc. with a thickness of 1~5 μm on the surface of the alumina ceramic. However, the thermal expansion of the thin film material is difficult to control, and the thermal expansion coefficient is very different from that of the substrate. Microcracks are likely to appear between the coating and the alumina ceramic substrate during thermal cycles, which in turn causes the coating to crack. Plasma spraying, such as patent CN110158015A, forms a Ni-Al alloy layer and a metal ceramic coating on the surface of the alumina ceramic in this way to obtain an absorbing material. The coating formed in this way has a high porosity, and the interface bonding is mainly mechanical anchoring. There is also the problem of unstable interface bonding between the coating and the alumina ceramic. Summary of the Invention

[0004] To address the technical issue of unstable bonding between existing alumina ceramics and their surface coatings, the present invention provides an alumina ceramic glaze based on household ceramic waste, as well as its preparation method and application. Once applied to the surface of an alumina ceramic to form a glaze layer, the glaze effectively improves the ceramic's insulation properties while also ensuring a highly stable bond between the glaze layer and the alumina ceramic, preventing significant insulation degradation and glaze cracking during thermal cycling.

[0005] The specific technical solutions of the present invention are:

[0006] In a first aspect, the present invention provides an alumina ceramic glaze based on daily ceramic waste, comprising the following raw materials in parts by weight: 28-42 parts of daily ceramic waste, 25-30 parts of kaolin, 6-12 parts of calcined talc, 3-7 parts of borax, 6-14 parts of alumina, 3-5 parts of zirconium oxide, 1-3 parts of lanthanum oxide, and 3-6 parts of self-repairing particles; the self-repairing particles comprise mesoporous alumina doped with Si and Zr and V2O5-B2O3-TeO2 glass filled in the pores of the mesoporous alumina; the V2O5-B2O3-TeO2 glass has a softening point of 200-300°C, wherein V2O5 accounts for 10-20 mol%, B2O3 accounts for 20-30 mol%, and the balance is TeO2; the daily ceramic waste comprises the following chemical components in weight fractions: 65-75% SiO2, 19-25% Al2O3, 0.01-0.80% Fe2O3, 0.01-1.00% CaO, 0.01-1% MgO, 1-5% K2O, 1-5% Na2O; in the mesoporous alumina doped with Si and Zr, the Si content is 15-20 wt%, and the Zr content is 1-5 wt%.

[0007] The glaze of the present invention, after being applied to the surface of an alumina ceramic (green body) to form a glaze layer, can improve the problems of surface discharge, leakage, and even insulation failure of the alumina ceramic, thereby improving the insulation properties of the alumina ceramic. It can also provide a high bonding stability between the glaze layer and the green body, thereby avoiding the problems of a significant decrease in insulation properties and cracking of the glaze layer during thermal cycling. Specifically:

[0008] (1) Daily-use ceramics have a high proportion of silicon and aluminum. After high-temperature firing, they are highly vitrified. Most of them can only be disposed of by landfill, which will occupy a large amount of land resources. The present invention uses daily-use ceramic waste in alumina ceramic glaze. While realizing its resource utilization, the high content of SiO2 and Al2O3 in daily-use ceramic waste and kaolin can serve as the main source of glass phase in the glaze layer. During the firing process, they fill the microcracks and pores on the surface of the alumina ceramic to form a continuous dense layer, thereby reducing the penetration of environmental media, charge accumulation and chemical erosion. In addition, the high aluminum and silicon system formed by daily-use ceramic waste and kaolin can better adapt to the thermal expansion of alumina ceramics, reduce the difference in thermal expansion coefficient between the glaze layer and the body, and thus improve the bonding stability between the glaze layer and the alumina ceramic body.

[0009] (2) The alkaline oxides (K2O, Na2O) contained in daily ceramic waste and the added talc and borax can promote the flow and spreading of glaze during the firing process, thereby improving the bonding strength between the glaze layer and the body.

[0010] (3) The high resistivity of ZrO2 and the low dielectric loss of La2O3 can synergistically inhibit charge migration on the surface of alumina ceramics, avoiding local electric field distortion and surface discharge. At the same time, La2O3 can also occupy grain boundary vacancies, inhibiting charge accumulation along the grain boundaries, and further improving the insulation properties of alumina ceramics after applying the glaze layer.

[0011] (4) When alumina ceramics are subjected to thermal shock, resulting in microcracks at the interface between the glaze layer and the body and inside the glaze layer, the V2O5-B2O3-TeO2 glass with a low softening point on the surface of the self-healing particles can soften and deform, filling the microcracks, thereby preventing these microcracks from causing environmental medium penetration and charge accumulation, allowing the alumina ceramics to maintain good insulation and avoid cracking of the glaze layer. In addition, the resistivity of V2O5-B2O3-TeO2 glass is relatively low. If it is directly added to the glaze layer, it is easy to cause poor insulation of the alumina ceramic after the glaze layer is applied. In this regard, the present invention uses mesoporous alumina doped with Si and Zr to load V2O5-B2O3-TeO2 glass: the mesoporous alumina modified by Si and Zr doping has good high temperature resistance and can maintain the stability of its mesoporous structure during the firing of the glaze layer. The present invention fills V2O5-B2O3-TeO2 glass in this mesoporous alumina, and can use the capillary action of the mesoporous alumina to restrain the molten V2O5-B2O3-TeO2 glass during the firing process of the glaze layer, thereby avoiding excessive outflow of V2O5-B2O3-TeO2 glass and forming a conductive channel in the glaze layer, thereby utilizing the mesoporous alumina to block the conductive channel.

[0012] Preferably, the household ceramic waste comprises the following chemical components by weight: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

[0013] Preferably, the self-repairing particles account for 3-6 wt% of all raw materials.

[0014] In a second aspect, the present invention provides a method for preparing the alumina ceramic glaze, comprising the following steps: adding mesoporous alumina doped with Si and Zr to the melted V2O5-B2O3-TeO2 glass liquid, performing vacuum pressure impregnation, taking out, cooling, and obtaining self-repairing particles; mixing the self-repairing particles with other raw materials to obtain alumina ceramic glaze.

[0015] Preferably, the vacuum pressure impregnation process comprises: evacuating to 20-30 Pa, maintaining for 1-2 hours, and then pressurizing to 2-5 MPa, maintaining for 5-8 hours.

[0016] Preferably, the preparation steps of the mesoporous alumina doped with Si and Zr include: dissolving polyether P123 in a reaction solvent, adjusting the pH value to 0.5-1.5, adding citric acid, aluminum isopropoxide, tetraethyl silicate and zirconium oxychloride, stirring and reacting for 2-4 hours, aging, drying, calcining and crushing.

[0017] Furthermore, the mass volume ratio of the aluminum isopropoxide, polyether P123 and ethanol is 1 g: 0.4-0.5 g: 7-15 mL.

[0018] Furthermore, the calcination process includes: heating to 400-450° C. at a rate of 1-2° C. / min and keeping the temperature for 3-4 hours.

[0019] In a third aspect, the present invention provides an application of the alumina ceramic glaze in the surface modification of alumina ceramics, comprising the following steps: mixing all raw materials of the alumina ceramic glaze with a dispersion medium to prepare a glaze slurry; applying the glaze slurry to the surface of an alumina ceramic body, and forming a glaze layer on the surface of the body after drying and firing.

[0020] Preferably, the thickness of the glaze layer is 45-55 μm.

[0021] Preferably, the glaze slurry is applied to the surface of the alumina ceramic body by spraying glaze.

[0022] Furthermore, the density of the glaze slurry is 1.6-1.8 g / cm 3 The glaze slurry flow rate during the glaze spraying process is 5~25 s / 100 mL.

[0023] Preferably, the sintering process comprises: heating to 700-800°C at a rate of 3-5°C / min, then heating to 1380-1420°C at a rate of 0.5-1.5°C / min, keeping warm for 2-3 hours, then cooling to 700-800°C at a rate of 4-6°C / min, and then cooling naturally.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The present invention uses daily ceramic waste and kaolin as the main raw materials in the glaze, which can be well filled into the micro cracks and pores on the surface of the alumina ceramic, effectively improving the insulation of the alumina ceramic, and at the same time, it can also make the glaze layer and the alumina ceramic have a higher bonding stability.

[0026] (2) The present invention uses ZrO2 and La2O3 in the glaze to synergistically inhibit charge migration on the surface of alumina ceramics, thereby improving the insulation properties of alumina ceramics to a greater extent.

[0027] (3) The present invention uses self-repairing particles with a special structure (V2O5-B2O3-TeO2 glass filled in the pores of mesoporous alumina doped with Si and Zr) in the glaze, which can produce a self-repairing effect on microcracks that appear during thermal cycling, so that the alumina ceramics maintain good insulation properties and avoid cracking of the glaze layer. At the same time, it can also avoid the introduction of V2O5-B2O3-TeO2 glass from having an excessive impact on the insulation properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Surface conditions of the alumina ceramics after thermal cycling after applying the glaze layer in each embodiment and comparative example. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the embodiments.

[0030] An alumina ceramic glaze based on daily ceramic waste comprises the following raw materials in parts by weight: 28-42 parts of daily ceramic waste, 25-30 parts of kaolin, 6-12 parts of calcined talc, 3-7 parts of borax, 6-14 parts of alumina, 3-5 parts of zirconium oxide, 1-3 parts of lanthanum oxide, and 3-6 parts of self-repairing particles; the self-repairing particles comprise mesoporous alumina doped with Si and Zr and a V2O5-B2O3-TeO2 glass filled in the pores of the mesoporous alumina; the V2O5-B2O3-TeO2 glass has a softening point of 200-300°C, wherein V2O5 accounts for 10-20 mol%, B2O3 accounts for 20-30 mol%, and the balance is TeO2; the daily ceramic waste comprises the following chemical components in weight fractions: 65-75% SiO2, 19-25% Al2O3, and 0.01-0.80% Fe2O3, 0.01-1.00% CaO, 0.01-1% MgO, 1-5% K2O, 1-5% Na2O; in the mesoporous alumina doped with Si and Zr, the Si content is 15-20 wt%, and the Zr content is 1-5 wt%.

[0031] In some specific embodiments, the household ceramic waste includes the following chemical components by weight: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

[0032] In some specific embodiments, the self-healing particles account for 3-6 wt% of all raw materials.

[0033] A method for preparing the alumina ceramic glaze comprises the following steps: adding mesoporous alumina doped with Si and Zr to a melted V2O5-B2O3-TeO2 glass liquid, performing vacuum pressure impregnation, removing the mixture, and cooling the mixture to obtain self-repairing particles; and mixing the self-repairing particles with other raw materials to obtain the alumina ceramic glaze.

[0034] In some specific embodiments, the vacuum pressure impregnation process includes: evacuating to 20-30 Pa, maintaining for 1-2 hours, and then pressurizing to 2-5 MPa, maintaining for 5-8 hours.

[0035] In some specific embodiments, the preparation steps of the mesoporous alumina doped with Si and Zr include: dissolving polyether P123 in a reaction solvent, adjusting the pH value to 0.5~1.5, adding citric acid, aluminum isopropoxide, tetraethyl silicate and zirconium oxychloride, stirring and reacting for 2~4 hours, aging, drying, heating to 400~450℃ at a rate of 1~2℃ / min, keeping warm for 3~4 hours, and crushing; the mass volume ratio of the aluminum isopropoxide, polyether P123 and ethanol is 1 g:0.4~0.5 g:7~15 mL.

[0036] In a third aspect, the present invention provides an application of the alumina ceramic glaze in the surface modification of alumina ceramics, comprising the following steps: mixing all raw materials of the alumina ceramic glaze with a dispersion medium to prepare a glaze slurry; applying the glaze slurry to the surface of an alumina ceramic body, and forming a glaze layer on the surface of the body after drying and firing.

[0037] In some specific embodiments, the glaze layer has a thickness of 45-55 μm.

[0038] In some specific embodiments, the glaze slurry is applied to the surface of the alumina ceramic body by spraying glaze, and the density of the glaze slurry is 1.6-1.8 g / cm 3 The glaze slurry flow rate during the glaze spraying process is 5~25 s / 100 mL.

[0039] In some specific embodiments, the sintering process includes: heating to 700-800°C at a rate of 3-5°C / min, then heating to 1380-1420°C at a rate of 0.5-1.5°C / min, keeping warm for 2-3 hours, and then cooling to 700-800°C at a rate of 4-6°C / min, and then cooling naturally.

[0040] The present invention is described below by way of specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, any changes and advantages that can be imagined by those skilled in the art are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0041] Example 1

[0042] An alumina ceramic glaze based on daily ceramic waste, the raw materials are composed of the following components by weight: 36 parts of daily ceramic waste, 29 parts of kaolin, 12 parts of calcined talc, 5 parts of borax, 12 parts of nano-alumina, 4 parts of nano-zirconia, 2 parts of lanthanum oxide, and 4 parts of self-repairing particles. Among them:

[0043] Household ceramic waste consists of the following chemical components in weight fractions: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

[0044] The self-healing particles were prepared by the following steps:

[0045] (1) Polyether P123 was dissolved in ethanol and the pH value was adjusted to 0.7 with concentrated hydrochloric acid. Then, citric acid, aluminum isopropoxide, tetraethyl silicate and zirconium oxychloride were added under stirring. The mass volume ratio of aluminum isopropoxide, polyether P123 and ethanol was 1 g:0.45 g:8 mL. After the addition was completed, stirring was continued for 2 h. After aging for 12 h, drying and calcination at 400 °C for 4 h, mesoporous alumina doped with Si and Zr was obtained, in which the Si and Zr contents were 15 wt% and 5 wt%, respectively.

[0046] (2) After V2O5-B2O3-TeO2 glass (the contents of V2O5, B2O3 and TeO2 are 10 mol%, 20 mol% and 70 mol%, respectively, the softening temperature is 285℃, and the glass transition temperature is 260℃) is heated and melted at 600℃, mesoporous alumina doped with Si and Zr is added thereto. The vacuum is evacuated to 25 Pa and maintained for 1 h. Then, the pressure is increased to 5 MPa and maintained for 6 h. The mesoporous alumina loaded with V2O5-B2O3-TeO2 glass is separated and naturally cooled to room temperature to obtain self-healing particles.

[0047] Using the glaze of this embodiment, a glaze layer with an average thickness of 50 μm is formed on the surface of the alumina ceramic by the following steps:

[0048] S1: Weigh each raw material by weight.

[0049] S2: After the household ceramic waste is coarsely crushed by a jaw crusher, it is ball-milled for 8 h until D50 = 10 μm to obtain household ceramic waste fragments.

[0050] S2: Mix the daily ceramic waste and all other raw materials, add water at a weight ratio of 100:60, and ball mill for 8 h. Then add more water to adjust the density to 1.72 g / cm3 , and obtain glaze slurry.

[0051] S3: The glaze slurry was applied to the alumina ceramic body (volume resistivity at 25°C was 8.73×10 12 Ω•cm) surface.

[0052] S4: After the alumina ceramic body with the glaze slurry applied is dried, it is placed in a shuttle kiln and fired according to the following firing schedule: heating to 800°C at a rate of 3°C / min, then heating to 1420°C at a rate of 1°C / min, keeping warm for 2 hours, and then slowly cooling to 800°C at a rate of 5°C / min, and finally naturally cooling to room temperature.

[0053] The performance of the alumina ceramic after the glaze layer was applied in this embodiment was tested, and the results were as follows: the glaze hardness (Mohs) was 8.1, the volume resistivity (25°C) was 1.08×10 13 Ω•cm; after 15 cycles of thermal cycling from 360-20℃ (both heating and cooling rates were 20℃ / min), the volume resistivity (25℃) was 1.08×10 13 Ω•cm, no cracks were observed (e.g. Figure 1 As shown; Figure 1 In the figures, the "JCU" on the ceramic pieces of each embodiment and comparative example is used to observe the transparency of the glaze layer. "JCU" is located between the body and the glaze layer. The clearer it is, the higher the transparency of the glaze layer.

[0054] Example 2

[0055] An alumina ceramic glaze based on daily ceramic waste, the raw materials are composed of the following components by weight: 32 parts of daily ceramic waste, 28 parts of kaolin, 10 parts of calcined talc, 5 parts of borax, 14 parts of nano-alumina, 5 parts of nano-zirconia, 2 parts of lanthanum oxide, and 3 parts of self-repairing particles. Among them:

[0056] Household ceramic waste consists of the following chemical components in weight fractions: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

[0057] The self-healing particles were prepared by the following steps:

[0058] (1) Polyether P123 was dissolved in ethanol and the pH value was adjusted to 0.7 with concentrated hydrochloric acid. Then, citric acid, aluminum isopropoxide, tetraethyl silicate and zirconium oxychloride were added under stirring. The mass volume ratio of aluminum isopropoxide, polyether P123 and ethanol was 1 g:0.45 g:8 mL. After the addition was completed, stirring was continued for 2 h. After aging for 12 h, the mixture was dried and calcined at 400 °C for 4 h to obtain mesoporous alumina doped with Si and Zr, in which the contents of Si and Zr were 18 wt% and 3 wt%, respectively.

[0059] (2) After V2O5-B2O3-TeO2 glass (the contents of V2O5, B2O3 and TeO2 are 10 mol%, 30 mol% and 60 mol%, respectively, the softening temperature is 260℃, and the glass transition temperature is 259℃) is heated and melted at 600℃, mesoporous alumina doped with Si and Zr is added thereto. The vacuum is evacuated to 25 Pa and maintained for 1 h. Then, the pressure is increased to 5 MPa and maintained for 6 h. The mesoporous alumina loaded with V2O5-B2O3-TeO2 glass is separated and naturally cooled to room temperature to obtain self-healing particles.

[0060] Using the glaze of this embodiment, a glaze layer with an average thickness of 50 μm is formed on the surface of the alumina ceramic by the following steps:

[0061] S1: Weigh each raw material by weight.

[0062] S2: After the household ceramic waste is coarsely crushed by a jaw crusher, it is ball-milled for 8 h until D50 = 10 μm to obtain household ceramic waste fragments.

[0063] S2: Mix the daily ceramic waste and all other raw materials, add water at a weight ratio of 100:60, and ball mill for 8 h. Then add more water to adjust the density to 1.72 g / cm 3 , and obtain glaze slurry.

[0064] S3: The glaze slurry was applied to the alumina ceramic body (volume resistivity of 8.73×10 12 Ω•cm) surface.

[0065] S4: After the alumina ceramic body with the glaze slurry applied is dried, it is placed in a shuttle kiln and fired according to the following firing schedule: heating to 800°C at a rate of 3°C / min, then heating to 1420°C at a rate of 1°C / min, keeping warm for 2 hours, and then slowly cooling to 800°C at a rate of 5°C / min, and finally naturally cooling to room temperature.

[0066] The performance of the alumina ceramic after the glaze layer was applied in this embodiment was tested, and the results were as follows: the glaze hardness (Mohs) was 8.2, the volume resistivity (25°C) was 1.29×10 13 Ω•cm; after 15 cycles of thermal cycling from 360-20℃ (both heating and cooling rates were 20℃ / min), the volume resistivity (25℃) was 1.29×10 13 Ω•cm, no cracks were observed (e.g. Figure 1 shown).

[0067] Example 3

[0068] An alumina ceramic glaze based on daily ceramic waste, the raw materials are composed of the following components by weight: 34 parts of daily ceramic waste, 30 parts of kaolin, 10 parts of calcined talc, 4 parts of borax, 10 parts of nano-alumina, 3 parts of nano-zirconia, 3 parts of lanthanum oxide, and 6 parts of self-repairing particles. Among them:

[0069] Household ceramic waste consists of the following chemical components in weight fractions: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

[0070] The self-healing particles were prepared by the following steps:

[0071] (1) Polyether P123 was dissolved in ethanol and the pH value was adjusted to 0.7 with concentrated hydrochloric acid. Then, citric acid, aluminum isopropoxide, tetraethyl silicate and zirconium oxychloride were added under stirring. The mass volume ratio of aluminum isopropoxide, polyether P123 and ethanol was 1 g:0.45 g:8 mL. After the addition was completed, stirring was continued for 2 h. After aging for 12 h, the mixture was dried and calcined at 400 °C for 4 h to obtain mesoporous alumina doped with Si and Zr, in which the contents of Si and Zr were 20 wt% and 1 wt%, respectively.

[0072] (2) After V2O5-B2O3-TeO2 glass (the contents of V2O5, B2O3 and TeO2 are 20 mol%, 30 mol% and 50 mol%, respectively, the softening temperature is 275℃, and the glass transition temperature is 260℃) is heated and melted at 600℃, mesoporous alumina doped with Si and Zr is added thereto. The vacuum is evacuated to 25 Pa and maintained for 1 h. Then, the pressure is increased to 5 MPa and maintained for 6 h. The mesoporous alumina loaded with V2O5-B2O3-TeO2 glass is separated and naturally cooled to room temperature to obtain self-healing particles.

[0073] Using the glaze of this embodiment, a glaze layer with an average thickness of 50 μm is formed on the surface of the alumina ceramic by the following steps:

[0074] S1: Weigh each raw material by weight.

[0075] S2: After the household ceramic waste is coarsely crushed by a jaw crusher, it is ball-milled for 8 h until D50 = 10 μm to obtain household ceramic waste fragments.

[0076] S2: Mix the daily ceramic waste and all other raw materials, add water at a weight ratio of 100:60, and ball mill for 8 h. Then add more water to adjust the density to 1.72 g / cm 3 , and obtain glaze slurry.

[0077] S3: The glaze slurry was applied to the alumina ceramic body (volume resistivity of 8.73×10 12 Ω•cm) surface.

[0078] S4: After the alumina ceramic body with the glaze slurry applied is dried, it is placed in a shuttle kiln and fired according to the following firing schedule: heating to 800°C at a rate of 3°C / min, then heating to 1420°C at a rate of 1°C / min, keeping warm for 2 hours, and then slowly cooling to 800°C at a rate of 5°C / min, and finally naturally cooling to room temperature.

[0079] The performance of the alumina ceramic after the glaze layer was applied in this embodiment was tested, and the results were as follows: the glaze hardness (Mohs) was 8.1, the volume resistivity (25°C) was 1.01×10 13 Ω•cm; after 15 cycles of thermal cycling from 360-20℃ (both heating and cooling rates were 20℃ / min), the volume resistivity (25℃) was 1.01×10 13 Ω•cm, no cracks were observed (e.g. Figure 1 shown).

[0080] Comparison and analysis of test results: In Examples 1 to 3, the volume resistivity of the alumina ceramics after applying the glaze layer is higher than that of the alumina ceramic bodies before applying the glaze layer, indicating that the insulation properties of the alumina ceramics can be effectively improved after applying the glaze layer on the surface of the alumina ceramics by the method of the present invention. This is because: in the glaze used in the present invention, the high content of SiO2 and Al2O3 in daily ceramic waste and kaolin can serve as the main source of the glass phase in the glaze layer, filling the microcracks and pores on the surface of the alumina ceramics during the firing process to form a continuous and dense layer, thereby reducing the penetration of environmental media, charge accumulation and chemical corrosion; the high resistivity of ZrO2 and the low dielectric loss of La2O3 can synergistically inhibit charge migration on the surface of the alumina ceramics, avoiding local electric field distortion and surface discharge. At the same time, La2O3 can also occupy grain boundary vacancies, inhibiting charge accumulation along the grain boundaries, further improving the insulation properties of the alumina ceramics after applying the glaze layer.

[0081] Comparative Example 1

[0082] An alumina ceramic glaze based on household ceramic waste. The raw materials are composed of the following components by weight: 36 parts household ceramic waste, 29 parts kaolin, 12 parts calcined talc, 5 parts borax, 12 parts nano-alumina, 4 parts nano-zirconia, and 2 parts lanthanum oxide. The household ceramic waste is composed of the following chemical components by weight: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

[0083] Using the glaze of this comparative example, a glaze layer with an average thickness of 50 μm was formed on the surface of the alumina ceramic by the following steps:

[0084] S1: Weigh each raw material by weight.

[0085] S2: After the household ceramic waste is coarsely crushed by a jaw crusher, it is ball-milled for 8 h until D50 = 10 μm to obtain household ceramic waste fragments.

[0086] S2: Mix the daily ceramic waste and all other raw materials, add water at a weight ratio of 100:60, and ball mill for 8 h. Then add more water to adjust the density to 1.72 g / cm 3 , and obtain glaze slurry.

[0087] S3: The glaze slurry was applied to the alumina ceramic body (volume resistivity of 8.73×10 12 Ω•cm) surface.

[0088] S4: After the alumina ceramic body with the glaze slurry applied is dried, it is placed in a shuttle kiln and fired according to the following firing schedule: heating to 800°C at a rate of 3°C / min, then heating to 1420°C at a rate of 1°C / min, keeping warm for 2 hours, and then slowly cooling to 800°C at a rate of 5°C / min, and finally naturally cooling to room temperature.

[0089] The performance of the alumina ceramics after applying the glaze layer in this comparative example was tested, and the results were as follows: the glaze hardness (Mohs) was 8.2, the volume resistivity (25°C) was 1.07×10 13 Ω•cm; after 15 cycles of thermal cycling from 360 to 20°C (both heating and cooling rates were 20°C / min), the volume resistivity (25°C) was 8.90×10 12 Ω•cm, cracks appear in the glaze layer (e.g. Figure 1 shown).

[0090] Comparison and analysis of test results: In Examples 1-3, after 15 cycles of thermal cycling at 360-20°C, the volume resistivity showed no significant change, and the glaze layer showed no cracks. In Comparative Example 1, after 15 cycles of thermal cycling at 360-20°C, the volume resistivity decreased, and cracks appeared in the glaze layer. This demonstrates that the present invention, by using special self-healing particles in the glaze, can improve the heat resistance of the glazed alumina ceramic, maintaining good insulation properties during thermal cycling and preventing glaze cracking. This is because: the higher silicon content in daily ceramic waste will lead to insufficient bonding between the glaze layer and the alumina ceramic body, resulting in microcracks between the glaze layer and the body during thermal cycling, triggering environmental medium penetration and charge accumulation, which in turn causes the insulation of the alumina ceramic to decrease. At the same time, the microcracks may further expand, causing the glaze layer to crack; when microcracks appear at the interface between the glaze layer and the body and inside the glaze layer during thermal cycling, the V2O5-B2O3-TeO2 glass with a low softening point on the surface of the self-healing particles can soften and deform, filling the microcracks, thereby preventing these microcracks from triggering environmental medium penetration and charge accumulation, and preventing the microcracks from further expanding and causing the glaze layer to crack.

[0091] Comparative Example 2

[0092] An alumina ceramic glaze based on daily ceramic waste, the raw materials of which are composed of the following components in parts by weight: 34 parts of daily ceramic waste, 30 parts of kaolin, 10 parts of calcined talc, 4 parts of borax, 10 parts of nano-alumina, 3 parts of nano-zirconium oxide, 3 parts of lanthanum oxide, and 2 parts of V2O5-B2O3-TeO2 glass.

[0093] Household ceramic waste consists of the following chemical components in weight fractions: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

[0094] In the V2O5-B2O3-TeO2 glass, the contents of V2O5, B2O3 and TeO2 are 20 mol%, 30 mol% and 50 mol% respectively, the softening temperature is 275℃ and the glass transition temperature is 260℃.

[0095] Using the glaze of this comparative example, a glaze layer with an average thickness of 50 μm was formed on the surface of the alumina ceramic by the following steps:

[0096] S1: Weigh each raw material by weight.

[0097] S2: After the household ceramic waste is coarsely crushed by a jaw crusher, it is ball-milled for 8 h until D50 = 10 μm to obtain household ceramic waste fragments.

[0098] S2: Mix the daily ceramic waste and all other raw materials, add water at a weight ratio of 100:60, and ball mill for 8 h. Then add more water to adjust the density to 1.72 g / cm 3 , and obtain glaze slurry.

[0099] S3: The glaze slurry was applied to the alumina ceramic body (volume resistivity of 8.73×10 12 Ω•cm) surface.

[0100] S4: After the alumina ceramic body with the glaze slurry applied is dried, it is placed in a shuttle kiln and fired according to the following firing schedule: heating to 800°C at a rate of 3°C / min, then heating to 1420°C at a rate of 1°C / min, keeping warm for 2 hours, and then slowly cooling to 800°C at a rate of 5°C / min, and finally naturally cooling to room temperature.

[0101] The performance of the alumina ceramics after applying the glaze layer in this comparative example was tested, and the results were as follows: the glaze hardness (Mohs) was 7.9, the volume resistivity (25°C) was 9.92×10 12 Ω•cm; after 15 cycles of thermal cycling from 360-20℃ (both heating and cooling rates were 20℃ / min), the volume resistivity (25℃) was 9.92×10 12 Ω•cm, no cracks were observed (e.g. Figure 1 shown).

[0102] Comparison and analysis of test results: Compared with Example 3, the volume resistivity of the alumina ceramic after the glaze layer is applied in Comparative Example 2 is lower. This shows that by filling the V2O5-B2O3-TeO2 glass into the mesoporous alumina doped with Si and Zr, the alumina ceramic after the glaze layer is applied can have better insulation properties. This is because: the resistivity of the V2O5-B2O3-TeO2 glass is relatively low. If it is added directly to the glaze layer, it is easy to cause the alumina ceramic after the glaze layer to have poor insulation. However, by filling the V2O5-B2O3-TeO2 glass into the mesoporous alumina doped with Si and Zr, the mesoporous alumina can be used to restrain the molten V2O5-B2O3-TeO2 glass during the glaze firing process, preventing the V2O5-B2O3-TeO2 glass from excessively flowing out and forming a conductive channel in the glaze layer, thereby utilizing the mesoporous alumina to block the conductive channel.

[0103] Comparative Example 3

[0104] An alumina ceramic glaze based on daily ceramic waste, the raw materials are composed of the following components by weight: 34 parts of daily ceramic waste, 30 parts of kaolin, 10 parts of calcined talc, 4 parts of borax, 10 parts of nano-alumina, 3 parts of nano-zirconia, 3 parts of lanthanum oxide, and 6 parts of self-repairing particles. Among them:

[0105] Household ceramic waste consists of the following chemical components in weight fractions: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

[0106] The self-healing particles were prepared by the following steps:

[0107] (1) Dissolve polyether P123 in ethanol, adjust the pH to 0.7 with concentrated hydrochloric acid, and then add citric acid and aluminum isopropoxide under stirring. The mass volume ratio of aluminum isopropoxide, polyether P123 and ethanol is 1 g:0.45 g:8 mL. After the addition is completed, continue stirring for 2 h. After aging for 12 h, dry and calcine at 400 °C for 4 h to obtain mesoporous alumina.

[0108] (2) After V2O5-B2O3-TeO2 glass (the contents of V2O5, B2O3 and TeO2 are 20 mol%, 30 mol% and 50 mol%, respectively, the softening temperature is 275℃, and the glass transition temperature is 260℃) is heated and melted at 600℃, mesoporous alumina is added thereto. The vacuum is evacuated to 25 Pa and maintained for 1 h. Then, the pressure is increased to 5 MPa and maintained for 6 h. The mesoporous alumina loaded with V2O5-B2O3-TeO2 glass is separated and naturally cooled to room temperature to obtain self-healing particles.

[0109] Using the glaze of this comparative example, a glaze layer with an average thickness of 50 μm was formed on the surface of the alumina ceramic by the following steps:

[0110] S1: Weigh each raw material by weight.

[0111] S2: After the household ceramic waste is coarsely crushed by a jaw crusher, it is ball-milled for 8 h until D50 = 10 μm to obtain household ceramic waste fragments.

[0112] S2: Mix the daily ceramic waste and all other raw materials, add water at a weight ratio of 100:60, and ball mill for 8 h. Then add more water to adjust the density to 1.72 g / cm 3 , and obtain glaze slurry.

[0113] S3: The glaze slurry was applied to the alumina ceramic body (volume resistivity of 8.73×1012 Ω•cm) surface.

[0114] S4: After the alumina ceramic body with the glaze slurry applied is dried, it is placed in a shuttle kiln and fired according to the following firing schedule: heating to 800°C at a rate of 3°C / min, then heating to 1420°C at a rate of 1°C / min, keeping warm for 2 hours, and then slowly cooling to 800°C at a rate of 5°C / min, and finally naturally cooling to room temperature.

[0115] The performance of the alumina ceramics after applying the glaze layer in this comparative example was tested, and the results were as follows: the glaze hardness (Mohs) was 8.0, the volume resistivity (25°C) was 9.95×10 12 Ω•cm; after 15 cycles of thermal cycling from 360-20℃ (both heating and cooling rates were 20℃ / min), the volume resistivity (25℃) was 9.95×10 12 Ω•cm, no cracks were observed (e.g. Figure 1 shown).

[0116] Comparison and analysis of test results: Compared with Example 3, the volume resistivity of the alumina ceramic after the glaze layer was applied in Comparative Example 3 was lower. This indicates that when the mesoporous alumina used to load the V2O5-B2O3-TeO2 glass is not doped with Si and Zr, the adverse effects of the introduction of the V2O5-B2O3-TeO2 glass on insulation cannot be effectively addressed. This is because: mesoporous alumina not doped with Si and Zr has poor thermal stability. Under the high temperature during the glaze firing process, the pores within the mesoporous alumina will collapse to a large extent, causing the molten V2O5-B2O3-TeO2 glass loaded therein to flow out and disperse into the glaze layer to form a conductive channel.

[0117] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used herein are conventional in the art and can be obtained from conventional commercial sources. The methods used herein are conventional in the art, unless otherwise specified.

[0118] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An alumina ceramic glaze based on daily ceramic waste, characterized in that: The invention comprises the following raw materials in parts by weight: 28-42 parts of daily ceramic waste, 25-30 parts of kaolin, 6-12 parts of calcined talc, 3-7 parts of borax, 6-14 parts of alumina, 3-5 parts of zirconium oxide, 1-3 parts of lanthanum oxide, and 3-6 parts of self-repairing particles; the self-repairing particles comprise mesoporous alumina doped with Si and Zr and V2O5-B2O3-TeO2 glass filled in the pores of the mesoporous alumina; the softening point of the V2O5-B2O3-TeO2 glass is 200-300°C, wherein the proportion of V2O5 is 10-20 mol%, the proportion of B2O3 is 20-30 mol%, and the balance is TeO2; the daily ceramic waste comprises the following chemical components in weight fractions: 65-75% SiO2, 19-25% Al2O3, 0.01-0.80% Fe2O3, 0.01-1.00% CaO, 0.01-1% MgO, 1-5% K2O, 1-5% Na2O; in the mesoporous alumina doped with Si and Zr, the Si content is 15-20 wt%, and the Zr content is 1-5 wt%.

2. The alumina ceramic glaze according to claim 1, characterized in that The household ceramic waste includes the following chemical components by weight: 71.20% SiO2, 21.49% Al2O3, 0.13% Fe2O3, 0.67% CaO, 0.32% MgO, 2.05% K2O, and 4.14% Na2O.

3. The alumina ceramic glaze according to claim 1, characterized in that The self-repairing particles account for 3-6 wt% of all raw materials.

4. A method for preparing the alumina ceramic glaze according to any one of claims 1 to 3, characterized in that: The following steps are involved: Mesoporous alumina doped with Si and Zr is added to the molten V2O5-B2O3-TeO2 glass liquid, vacuum pressure impregnation is performed, and then the mixture is taken out and cooled to obtain self-repairing particles; the self-repairing particles are mixed with other raw materials to obtain alumina ceramic glaze.

5. The preparation method according to claim 4, wherein The preparation steps of the Si- and Zr-doped mesoporous alumina include: dissolving polyether P123 in a reaction solvent, adjusting the pH value to 0.5-1.5, adding citric acid, aluminum isopropoxide, tetraethyl silicate and zirconium oxychloride, stirring and reacting for 2-4 hours, aging, drying, calcining and crushing.

6. Use of the alumina ceramic glaze according to any one of claims 1 to 3 in surface modification of alumina ceramics, characterized in that: The following steps are involved: All raw materials of the alumina ceramic glaze are mixed with a dispersion medium to prepare a glaze slurry; the glaze slurry is applied to the surface of the alumina ceramic body, and a glaze layer is formed on the surface of the body after drying and firing.

7. The use according to claim 6, characterized in that The thickness of the glaze layer is 45-55 μm.

8. The use according to claim 6, characterized in that The method of applying the glaze slurry to the surface of the alumina ceramic body is spraying glaze.

9. The use according to claim 8, characterized in that The density of the glaze slurry is 1.6-1.8 g / cm 3 The glaze slurry flow rate during the glaze spraying process is 5~25 s / 100 mL.

10. The use according to claim 6, characterized in that The sintering process includes: heating to 700-800°C at a rate of 3-5°C / min, then heating to 1380-1420°C at a rate of 0.5-1.5°C / min, keeping warm for 2-3 hours, then cooling to 700-800°C at a rate of 4-6°C / min, and then cooling naturally.

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