Alumina ceramic, preparation method thereof and ceramic structural member

Abstract

The invention relates to the technical field of structural ceramics, and discloses an aluminum oxide ceramic, the aluminum oxide ceramic comprises a doping element, the doping element comprises at least one of magnesium, calcium, yttrium, lanthanum, zirconium and cerium, and the doping amount of the doping element is 600ppm-1000ppm. According to the aluminum oxide ceramic provided by the invention, through uniform doping of trace doping elements in aluminum oxide, modification of a grain boundary structure, grain morphology and size of the aluminum oxide ceramic is realized, so that the aluminum oxide ceramic provided by the invention is high-purity aluminum oxide ceramic with excellent mechanical strength, electrical properties and thermal conductivity.

Description

Technical Field

[0001] This application relates to the field of structural ceramics technology, specifically to alumina ceramics and their preparation methods, and ceramic structural components. Background Technology

[0002] Alumina ceramics, as one of the earliest studied structural ceramic materials, have been widely used in industry due to their low cost and excellent comprehensive performance. Especially in the semiconductor field, high-strength, high-thermal-conductivity alumina ceramics play a crucial role in semiconductor equipment components, serving as an important material for manufacturing ceramic backplates, electrostatic chucks, and other parts. Therefore, designing and optimizing the fabrication of high-performance alumina ceramics that are compatible with semiconductor process routes is an important research topic in the manufacturing industry of precision ceramic components for semiconductor process equipment.

[0003] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0004] In a first aspect of this application, an alumina ceramic is provided, wherein the alumina ceramic comprises a dopant element, the dopant element being at least one selected from magnesium, calcium, yttrium, lanthanum, zirconium, and cerium, and the doping amount of the dopant element is 600ppm-1000ppm.

[0005] In some embodiments, the alumina ceramic has an average grain size of 540 nm to 710 nm and a relative density of 98.5%.

[0006] In some embodiments, the flexural strength of the alumina ceramic is greater than or equal to 480 MPa; and / or, the thermal conductivity of the alumina ceramic is 25 W / (m·K); and / or, the resistivity of the alumina ceramic is greater than or equal to 10 Ω·m. 14 Ω·cm.

[0007] In a second aspect of this application, a method for preparing alumina ceramics is proposed, comprising: molding alumina powder to obtain a ceramic green body; pre-sintering the ceramic green body to obtain a pre-fired ceramic body; impregnating the pre-fired ceramic body with an impregnation solution, wherein the concentration of the dopant element in the impregnation solution is 0.01 mol / L-0.02 mol / L; after the impregnation treatment, in-situ precipitation treatment of the pre-fired ceramic body with ammonia water, wherein the volume concentration of the ammonia water is 10%-30%; and sintering the pre-fired ceramic body to obtain the alumina ceramic.

[0008] In some embodiments, the specific surface area of ​​the alumina powder is 12.5 m². 2 / g-13.5m 2 / g, wherein the particle size of the alumina powder is 100nm-140nm.

[0009] In some embodiments, the impregnation solution includes at least one of the dopant elements, namely nitrates and sulfates.

[0010] In some embodiments, the molding process is performed at a pressure of 45 MPa-55 MPa and for a time of 1 min-2 min.

[0011] In some embodiments, the temperature of the pre-sintering treatment is 900℃-1000℃, and the holding time of the pre-sintering treatment is 30min-60min.

[0012] In some embodiments, the sintering process includes a first sintering process, a second sintering process, and a third sintering process performed sequentially. The first sintering process is performed at a temperature of 100℃-120℃, with a heating rate of 5℃ / min-10℃ / min and a holding time of 20min-30min. The second sintering process is performed at a temperature of 900℃-1000℃, with a heating rate of 5℃ / min-10℃ / min and a holding time of 30min-60min. The third sintering process is performed at a temperature of 1300℃-1400℃, with a heating rate of 5℃ / min-10℃ / min and a holding time of 60min-240min.

[0013] In some embodiments, the method further includes: after the forming process, subjecting the ceramic blank to static pressing, wherein the static pressing pressure is 100MPa-200MPa and the static pressing time is 3min-5min.

[0014] In some embodiments, the method further includes: during the impregnation process, performing a heating process, wherein the temperature range of the heating process is 40°C-80°C; and / or performing a vacuum process, wherein the vacuum degree of the vacuum process is 1000Pa-3000Pa.

[0015] In a third aspect of this application, a ceramic structural component is proposed, which is made using the alumina ceramic proposed in this application or prepared using the method proposed in this application.

[0016] The beneficial effects of the technical solution proposed in this application include at least the following:

[0017] (1) The alumina ceramic of this application contains doping elements with extremely low doping concentration and uniform doping, which is beneficial to improving the purity of the alumina ceramic.

[0018] (2) The method of this application can better maintain the surface activity of alumina powder, and alumina ceramics with a relative density higher than 98.5% can be sintered at 1300℃.

[0019] (3) By controlling the doping elements, the prepared alumina ceramics achieved a flexural strength of 530 MPa, a thermal conductivity of 30 W / (m·K), and a thermal conductivity higher than 10. 14 resistivity in Ω·cm;

[0020] (4) The microstructure of the prepared alumina ceramic is uniform and without obvious defects, which is conducive to meeting the requirements of the semiconductor industry for ceramic structural parts. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0022] Figure 1 This is a flowchart of a method for preparing alumina ceramics in one embodiment of this application;

[0023] Figure 2 (A) is a SEM image of the cross-section of the alumina ceramic prepared in Example 1 of this application;

[0024] Figure 2 (B) is a SEM image of the polished surface of the alumina ceramic prepared in Example 1 of this application after hot corrosion;

[0025] Figure 3 This is a SEM image of the surface of the alumina ceramic prepared in Example 2 of this application.

[0026] Figure 4 This is a diagram showing the effect of hot corrosion treatment on the alumina ceramic prepared in Example 4 of this application. Detailed Implementation

[0027] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0028] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0029] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0030] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0031] The "range" disclosed in this application 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 arbitrarily combined; 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 a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 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 application, 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" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥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.

[0032] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0033] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0034] Since the 1950s, when GE scientist Coble successfully prepared high-performance transparent ceramics by doping alumina with magnesium oxide, modifying alumina ceramics through doping has become a research hotspot. Over the decades, various dopants such as calcium oxide, silicon oxide, and yttrium oxide have been studied to some extent. However, with the increasing demands on the electrical performance of ceramic components in semiconductor processes, the impact of impurity elements on the electrical insulation and dielectric properties of alumina ceramics has become significant, and high-purity alumina with extremely low doping levels has gradually become a new focus. Against this backdrop, traditional ball milling methods struggle to achieve uniform distribution of trace dopants in the ceramic matrix; achieving the desired doping effect requires introducing larger amounts of dopants, which is insufficient to meet the industry's demand for high-purity alumina ceramics. Therefore, there is an urgent need to develop methods that can modify and optimize alumina ceramics while ensuring purity.

[0035] Besides doping modification, the sintering temperature of alumina ceramics is also a crucial indicator in industrial applications. Achieving low-temperature sintering of alumina ceramics not only reduces energy consumption in industrial production but also allows for compatibility with co-firing processes commonly used in the semiconductor industry, enabling composites with other materials. In recent years, by using highly active sintering alumina powders with small particle size and high specific surface area, it has become possible to sinter alumina ceramics at temperatures as low as 1300℃, a significant reduction compared to the traditional 1600℃ sintering temperature. However, highly active sintering alumina powders are highly sensitive to surface activity, making further optimization using traditional methods difficult. Therefore, exploring methods to improve and optimize the properties of alumina ceramics while maintaining the sintering activity of highly active sintering alumina powders is of great significance for related industrial applications.

[0036] In a first aspect of this application, an alumina ceramic is provided, wherein the alumina ceramic comprises a dopant element, the dopant element being at least one selected from magnesium, calcium, yttrium, lanthanum, zirconium, and cerium, and the doping amount of the dopant element is 600ppm-1000ppm.

[0037] The alumina ceramic proposed in this application modifies the grain boundary structure, grain morphology, and size of alumina ceramics through uniform doping with trace amounts of doping elements. As a result, the alumina ceramic of this application is a high-purity alumina ceramic with excellent mechanical strength, electrical properties, and thermal conductivity.

[0038] In some embodiments, the alumina ceramic has an average grain size of 540 nm to 710 nm and a relative density greater than or equal to 98.5%. Therefore, the alumina ceramic possesses high mechanical properties and high density.

[0039] In some embodiments, the flexural strength of the alumina ceramic is greater than or equal to 480 MPa; and / or, the thermal conductivity of the alumina ceramic is 25 W / (m·K); and / or, the resistivity of the alumina ceramic is greater than or equal to 10 Ω·m. 14 Ω·cm. In the alumina ceramic, the doping elements are distributed relatively uniformly, which is beneficial to improving the thermal conductivity and resistivity of the alumina ceramic.

[0040] In a second aspect of this application, a method for preparing alumina ceramics is proposed, with reference to... Figure 1 ,include:

[0041] S1: The alumina powder is shaped to obtain a ceramic green body. This improves the density of the ceramic green body, which is beneficial for increasing the relative density of the prepared alumina ceramic.

[0042] S2: The ceramic green body is pre-sintered to obtain a pre-fired ceramic body. This improves the crystal distribution and crystal structure of the pre-fired ceramic body, which is beneficial for the effective doping of subsequent doping elements in the impregnation process.

[0043] S3: The ceramic pre-sintered body is impregnated with an impregnation solution containing a dopant element concentration of 0.01 mol / L to 0.02 mol / L. The impregnation solution is prepared by dissolving a soluble salt containing the desired dopant element in deionized water at a specific concentration. The prepared alumina pre-sintered body is then placed in the solution and allowed to stand, allowing the dopant element ions to fill the pores of the ceramic pre-sintered body, thus introducing the dopant element. This process also facilitates the uniform doping of extremely low concentration dopant elements and improves the purity of the alumina ceramic.

[0044] S4: After the impregnation treatment, the ceramic pre-fired body is subjected to in-situ precipitation treatment with ammonia water, the volume concentration of which is 10%-30%. This allows the dopant ions to precipitate in situ and remain in the ceramic pre-fired body, thus completing the entire doping process.

[0045] S5: The pre-fired ceramic body is sintered to obtain the alumina ceramic. This completes the sintering of the pre-fired ceramic body, producing alumina ceramic with high strength and high thermal conductivity.

[0046] In some embodiments, the specific surface area of ​​the alumina powder is 12.5 m². 2 / g-13.5m 2 / g, wherein the alumina powder has a particle size of 100nm-140nm. The aforementioned alumina powder with a large specific surface area can effectively reduce the sintering temperature and the grain size of the prepared alumina ceramic, which is beneficial to improving the mechanical properties of the alumina ceramic.

[0047] In some embodiments, the impregnation solution includes at least one of the nitrate and sulfate salts of the dopant element. Using the impregnation solution can reduce the introduction of other impurities and also facilitates sufficient solubility of the dopant element in the impregnation solution to achieve a more uniform doping effect.

[0048] In some embodiments, the molding process is carried out at a pressure of 45 MPa-55 MPa and for a time of 1 min-2 min. Molding conditions within the aforementioned range can reduce powder agglomeration during unidirectional pressure loading, and the required pressure to maintain the molding process is lower, which helps to reduce the molding time while maintaining molding strength.

[0049] In some embodiments, the pre-sintering temperature is 900℃-1000℃, and the holding time is 30min-60min. At the aforementioned temperature and time, the pre-sintering process provides sufficient heat energy, reducing the decrease in strength of the ceramic pre-sintered body due to excessively low temperature, or the decrease in porosity due to excessively high temperature. This facilitates uniform impregnation and doping of dopants during subsequent impregnation processes.

[0050] In some embodiments, the sintering process includes a first sintering process, a second sintering process, and a third sintering process performed sequentially. The first sintering process is performed at a temperature of 100℃-120℃, with a heating rate of 5℃ / min-10℃ / min and a holding time of 20min-30min. The second sintering process is performed at a temperature of 900℃-1000℃, with a heating rate of 5℃ / min-10℃ / min and a holding time of 30min-60min. The third sintering process is performed at a temperature of 1300℃-1400℃, with a heating rate of 5℃ / min-10℃ / min and a holding time of 60min-240min. The first sintering process, performed within the aforementioned parameter range, removes moisture introduced during the doping process. During the second sintering process, which meets the aforementioned conditions, the hydroxide precipitate of the dopant element can be converted into an oxide sintering aid, which is beneficial for reducing the sintering temperature. In the third sintering process that meets the aforementioned parameter range, the sintering and densification process of alumina ceramics can be achieved.

[0051] In some embodiments, the method further includes: after the molding process, subjecting the ceramic green body to static pressing treatment, wherein the static pressing pressure is 100MPa-200MPa and the static pressing time is 3min-5min. This is beneficial for further improving the density of the prepared ceramic green body.

[0052] In some embodiments, the process further includes: during the impregnation process, performing a heating treatment at a temperature range of 40°C to 80°C; and / or performing a vacuum treatment at a vacuum degree of 1000Pa to 3000Pa. This facilitates the removal of gas from the pores of the ceramic pre-fired body during the impregnation process, thereby accelerating the impregnation and doping process.

[0053] In a third aspect, this application proposes a ceramic structural component, which is prepared using the alumina ceramic proposed in this application or by the method proposed in this application. The alumina ceramic proposed in this application has high thermal conductivity and electrical insulation properties, as well as high mechanical strength, and can be applied in the semiconductor industry, such as in the preparation of ceramic thermally conductive substrates and ceramic electrostatic chucks.

[0054] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0055] Example 1

[0056] S1: Weigh 30g of high-purity alumina powder with a particle size of 120nm, pour it into a stainless steel mold with a diameter of 50mm, and dry press it for three minutes under a pressure of 50MPa. Then, place it in a rubber mold and press it under an isostatic pressure of 200MPa for 5 minutes with silicone oil as the pressure transmission medium to obtain a ceramic green body with a density of about 55%.

[0057] S2: Place the formed ceramic blank in a box furnace, heat it to 1000℃ at a heating rate of 5℃ / min and hold it for 30min, and then cool it down to room temperature at a cooling rate of 5℃ / min to obtain the pre-fired ceramic body.

[0058] S3: Dissolve 0.103g of magnesium nitrate tetrahydrate completely in 20mL of deionized water to prepare Mg 2+ An impregnation solution with an ion concentration of 0.02 mol / L was prepared, and the pre-fired ceramic body was then placed in the impregnation solution, ensuring that the pre-fired ceramic body was completely submerged in the impregnation solution and left to stand for 1 hour.

[0059] S4: Then, the pre-fired ceramic body is removed, the residual solution on the surface is removed, and it is completely immersed in an ammonia solution of a certain concentration and left to stand for 10 minutes.

[0060] S5: Finally, after the impregnated ceramic pre-sintered body is thoroughly dried, it is placed in a box furnace for sintering again. First sintering treatment: the temperature is raised to 120℃ at a heating rate of 5℃ / min and held for 30min. Second sintering treatment: the temperature is raised to 1000℃ at the same heating rate and held for 1h. Third sintering treatment: the temperature is raised to 1300℃ at the same heating rate and held for 1h, and then cooled to room temperature at a cooling rate of 5℃ / min to obtain Mg-doped alumina ceramic with a density of 99.04%.

[0061] refer to Figure 2 The obtained alumina ceramic has a three-point flexural strength of 530 MPa, a room temperature thermal conductivity of 30.1 W / (m·K), and a room temperature resistivity greater than 10 Ω·m. 14 The microstructure is uniform, with equiaxed grains and an average grain size of approximately 630 nm.

[0062] Example 2

[0063] Example 2 is the same as Example 1, except that the impregnation solution is prepared by completely dissolving 0.052 g of magnesium nitrate tetrahydrate in 20 mL of deionized water. 2+ A solution with an ion concentration of 0.01 mol / L.

[0064] refer to Figure 2 A Mg-doped alumina ceramic with a density of 98.86% was obtained. The sample exhibited a three-point flexural strength of 503 MPa, a room-temperature thermal conductivity of 30.4 W / (m·K), and a room-temperature resistivity greater than 10⁻⁶. 14 The microstructure is uniform, with equiaxed central grains and an average grain size of approximately 710 nm.

[0065] Example 3

[0066] Example 3 is the same as Example 1, except that the pre-sintering temperature is 900°C.

[0067] A Mg-doped alumina ceramic with a density of 99.02% was obtained. The sample exhibited a three-point flexural strength of 528 MPa, a room-temperature thermal conductivity of 29.8 W / (m·K), and a room-temperature resistivity greater than 10⁻⁶. 14 The microstructure is uniform, with equiaxed grains and an average grain size of approximately 610 nm.

[0068] Example 4

[0069] Example 4 is the same as Example 1, except that the temperature of the third sintering treatment is 1350°C.

[0070] A Mg-doped alumina ceramic with a density of 99.45% was obtained. The sample exhibited a three-point flexural strength of 513 MPa, a room-temperature thermal conductivity of 30.6 W / (m·K), and a room-temperature resistivity greater than 10⁻⁶. 14 The microstructure is uniform, with equiaxed grains and an average grain size of approximately 690 nm.

[0071] Example 5

[0072] Example 5 is the same as Example 4, except that the impregnation solution is prepared by completely dissolving 0.094 g of calcium nitrate tetrahydrate in 20 mL of deionized water to form a solution with a Ca ion concentration of 0.02 mol / L.

[0073] refer to Figure 3 A Ca-doped alumina ceramic with a density of 99.32% was obtained. This sample exhibited a three-point flexural strength of 528 MPa, a room-temperature thermal conductivity of 28.9 W / (m·K), and a room-temperature resistivity greater than 10⁻⁶. 14 The microstructure is uniform, with equiaxed central grains and rod-shaped grains with an aspect ratio of about 3:1 on the surface. The average grain size is about 545 nm.

[0074] Example 6

[0075] Example 6 is the same as Example 4, except that the impregnation solution is prepared by completely dissolving 0.152 g of yttrium nitrate hexahydrate in 20 mL of deionized water to form a solution with a Y ion concentration of 0.02 mol / L.

[0076] Y-doped alumina ceramics with a density of 98.76% were obtained. The sample exhibited a three-point flexural strength of 498 MPa, a room-temperature thermal conductivity of 29.2 W / (m·K), and a room-temperature resistivity greater than 10⁻⁶. 14 The microstructure is uniform, with equiaxed central grains and an average grain size of approximately 478 nm.

[0077] Comparative Example 1

[0078] Comparative Example 1 is consistent with Example 1, except that the doping is not carried out by impregnation, that is, the steps S1, S2, S3 and S4 are not performed. The alumina powder described in S1 is added to the magnesium nitrate solution described in S3 and mixed evenly. After the powder is taken out, it is shaped according to the molding method described in S1, and finally sintered by the same sintering method as in S5.

[0079] A Mg-doped alumina ceramic with a density of 97.01% was obtained. The sample exhibited a three-point flexural strength of 405 MPa, a room-temperature thermal conductivity of 26.23 W / (m·K), and a room-temperature resistivity greater than 10⁻⁶. 14The microstructure is uniform, with equiaxed central grains and an average grain size of approximately 405 nm.

[0080] Test method:

[0081] 1. Bending strength test

[0082] Bending strength was tested using a three-point bending test method. The ceramic sample was machined into a 3mm × 4mm × 32mm square columnar specimen, and the tension surface was polished. The 4mm wide side of the specimen was symmetrically placed on a metal roller with a span of 30mm, while a load was applied to the middle of the specimen via another metal roller, gradually increasing the load until the specimen fractured. The bending strength (unit: MPa) of the specimen tested using this method was:

[0083] σ f =3FL / 2bd 2

[0084] In the formula, F is the maximum load (unit: N), L is the span (unit: mm), b is the specimen width (unit: mm), and b is the specimen thickness parallel to the loading direction (unit: mm).

[0085] 2. Thermal conductivity test

[0086] Thermal conductivity was tested using the transient planar heat source method. Two identical cylindrical samples were placed symmetrically on either side of a planar heat source, and the thermal conductivity of the samples was obtained using a Hot Disk thermal constant analyzer.

[0087] 3. Resistivity test

[0088] Silver electrodes are uniformly coated on both sides of the sample to be tested. A voltage is applied to both sides, and the current passing through the sample is measured simultaneously. The resistance of the sample can be calculated, and the resistivity can be obtained by combining this with the shape of the sample. The corresponding calculation formula is:

[0089] ρ=Ud / IS

[0090] In the formula, U is the voltage difference between the two sides of the sample, I is the current through the sample, d is the sample thickness parallel to the current direction, and S is the area of ​​the electrodes on both sides.

[0091] 4. Grain size test

[0092] After obtaining the SEM microstructure image of the polished surface of the sample, the grain size of the sample was statistically obtained by the truncation method. At least 200 grains were counted for each image, and the average size obtained by the truncation method was multiplied by a coefficient of 1.56 to obtain the average grain size of the sample.

[0093] 5. Hot corrosion treatment

[0094] refer to Figure 4 In Example 4, the alumina ceramic sample was ground and polished, then heated to 1100℃ at a heating rate of 5℃ / min and held for 2 hours to reveal its microstructure. It was observed that the sample exhibited a uniform equiaxed microstructure, small grain size, low porosity, and high mechanical properties.

[0095] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0096] In this application, the order in which the steps are written does not imply a strict execution order and does not limit the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps in this application can be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can 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.

[0097] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An alumina ceramic, characterized in that, The alumina ceramic contains a doping element, which includes at least one of magnesium, calcium, yttrium, lanthanum, zirconium, and cerium, and the doping amount of the doping element is 600ppm-1000ppm.

2. The alumina ceramic according to claim 1, characterized in that, The alumina ceramic has an average grain size of 540nm-710nm and a relative density of 98.5%.

3. The alumina ceramic according to claim 1, characterized in that, Satisfy at least one of the following (1) to (3): (1) The bending strength of the alumina ceramic is greater than or equal to 480 MPa; (2) The thermal conductivity of the alumina ceramic is greater than or equal to 25 W / (m·K); (3) The resistivity of the alumina ceramic is greater than or equal to 10. 14 Ω·cm.

4. A method for preparing the alumina ceramic according to any one of claims 1-3, characterized in that, include: Alumina powder is shaped to obtain a ceramic green body; The ceramic green body is subjected to pre-sintering treatment to obtain a pre-fired ceramic body; The pre-fired ceramic body is impregnated with an impregnation solution, wherein the concentration of the dopant element in the impregnation solution is 0.01 mol / L-0.02 mol / L; After the impregnation treatment, the pre-fired ceramic body is subjected to in-situ precipitation treatment with ammonia water, the volume concentration of which is 10%-30%. The ceramic pre-fired body is sintered to obtain the alumina ceramic.

5. The method according to claim 4, characterized in that, The specific surface area of ​​the alumina powder is 12.5 m². 2 / g-13.5m 2 / g, wherein the alumina powder has a particle size of 100nm-140nm; and / or, the impregnation solution includes at least one of the dopant elements, namely nitrate and sulfate.

6. The method according to claim 4, characterized in that, The molding process is performed at a pressure of 45 MPa-55 MPa for 1 min-2 min; and / or, The temperature of the pre-sintering treatment is 900℃-1000℃, and the holding time of the pre-sintering treatment is 30min-60min.

7. The method according to claim 4, characterized in that, The sintering process includes a first sintering process, a second sintering process, and a third sintering process performed sequentially. The temperature of the first sintering process is 100℃-120℃, the heating rate of the first sintering process is 5℃ / min-10℃ / min, and the holding time of the first sintering process is 20min-30min. The temperature of the second sintering treatment is 900℃-1000℃, the heating rate of the second sintering treatment is 5℃ / min-10℃ / min, and the holding time of the second sintering treatment is 30min-60min; The temperature of the third sintering treatment is 1300℃-1400℃, the heating rate of the third sintering treatment is 5℃ / min-10℃ / min, and the holding time is 60min-240min.

8. The method according to any one of claims 4-7, characterized in that, Also includes: After the forming process, the ceramic blank is subjected to static pressing treatment. The static pressing treatment pressure is 100MPa-200MPa, and the static pressing treatment time is 3min-5min.

9. The method according to any one of claims 4-7, characterized in that, Also includes: During the impregnation process, a heating process is performed, the temperature range of which is 40°C-80°C; and / or a vacuum process is performed, the vacuum degree of which is 1000Pa-3000Pa.

10. A ceramic structural component, characterized in that, The alumina ceramic according to any one of claims 1-3, or the method according to any one of claims 4-9, is used for preparation.

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