Self-cleaning aluminum oxide ceramic material and preparation method thereof

Abstract

The invention relates to the technical field of ceramic materials, in particular to a self-cleaning aluminum oxide ceramic material and a preparation method thereof. The self-cleaning aluminum oxide ceramic material comprises an aluminum oxide ceramic matrix and a hydrophobic layer formed on the surface of the aluminum oxide ceramic matrix, and the hydrophobic layer is obtained by performing surface grafting modification on the aluminum oxide ceramic matrix; the contact angle between the alumina ceramic material and water is larger than 110 degrees. According to the self-cleaning aluminum oxide ceramic material, the surface of the aluminum oxide ceramic matrix is subjected to hydrophobic modification, so that a hydrophobic layer is formed on the surface of the aluminum oxide ceramic matrix, the surface of the aluminum oxide ceramic material can be in a super-hydrophobic state, and the self-cleaning effect can be achieved on the premise that the electrical / mechanical / thermal properties of the material are not affected.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and particularly relates to a self-cleaning alumina ceramic material and a preparation method thereof. Background Art

[0002] In recent years, the integration degree of chips has been continuously improved and the feature size has been continuously reduced. In order to meet the improvement of the integration degree of integrated circuits (ICs) and the reduction of feature size, IC manufacturing technology has also been developing rapidly. The manufacturing of ICs includes hundreds of process steps, and the silicon wafers need to be transported back and forth in these process equipment for processing and testing. In order to ensure the manufacturing quality of ICs, it is necessary to ensure that the silicon wafers remain absolutely stable during the transmission between process equipment, and at the same time, it is necessary to ensure that the silicon wafers will not warp, deform or shift under the action of processing load, which puts strict requirements on the silicon wafer clamping technology.

[0003] An electrostatic chuck (ESC) is the most widely used silicon wafer clamping tool in modern semiconductor industry. The electrostatic chuck has the following advantages compared with the previous silicon wafer clamping methods: 1. The adsorption effect is evenly distributed on the surface of the silicon wafer, and the silicon wafer will not warp or deform; 2. The adsorption force is continuous and stable, which can ensure the processing accuracy of the silicon wafer; 3. The electrostatic chuck has little pollution to the silicon wafer and no damage to the silicon wafer; 4. It can be applied to high vacuum environments, etc.

[0004] As a silicon wafer clamping tool, the electrostatic chuck needs to go through multiple silicon wafer processing procedures, such as plasma immersion, ion doping, ion implantation, physical vapor deposition, chemical vapor deposition, etc. The electrostatic chuck generally uses alumina ceramic as the dielectric. In such a silicon wafer processing environment, the ceramic structure is exposed to the plasma environment. As Figure 1 shown, stains will adhere to the surface of the alumina ceramic, resulting in a deterioration of the surface roughness. Such a situation will directly cause a change in the contact state between the surface of the electrostatic chuck and the silicon wafer, leading to short circuits between the wirings of LSI, etc., greatly reducing the processing accuracy of the wafer and the service life of the electrostatic chuck. In order to remove the stains adhering to the surface of the alumina ceramic, it is necessary to rinse the surface of the alumina ceramic with clean water before use. However, although the existing alumina ceramic surface has certain hydrophobicity, its hydrophobicity is not ideal enough, resulting in some stains still remaining on the surface of the alumina ceramic after washing with water, making the cleaning effect unsatisfactory.

[0005] Currently, researchers usually use two methods to address this problem. One is to coat the outer surface of alumina ceramics by spraying or sputtering a thin film of alumina or yttrium oxide. The drawback is that the sprayed film may be damaged by plasma, metal particles fly everywhere in the plasma processing device, the processing device is contaminated, and the metal particles transferred to the wafer are likely to cause heavy metal pollution. The other is to dope alumina ceramics, and titanium oxide is mostly selected as the doping element, which enhances the corrosion resistance while reducing the volume resistivity. However, its addition amount is not easy to control, and excessive addition of titanium oxide is likely to cause excessive current flow. Summary of the Invention

[0006] The present invention provides a self-cleaning alumina ceramic material and a preparation method thereof. The present invention performs surface modification on alumina ceramics, which can achieve the function of self-cleaning without affecting the electrical / mechanical / thermal properties of the material.

[0007] According to the first aspect of the present invention, a self-cleaning alumina ceramic material is provided, including an alumina ceramic matrix and a hydrophobic layer formed on the surface of the alumina ceramic matrix. The hydrophobic layer is obtained by surface graft modification of the alumina ceramic matrix; the contact angle between the alumina ceramic material and water > 110°.

[0008] In the above solution, a self-cleaning alumina ceramic material of the present invention forms a hydrophobic layer through surface graft modification on the surface of the alumina ceramic matrix, so that the contact angle between the alumina ceramic material and water > 110°, enabling the surface of the alumina ceramic material to be in a superhydrophobic state. As Figure 2 shown, when the stains generated during the operation of the electrostatic chuck adhere to the surface of the alumina ceramic material of the present invention, during the cleaning process with water, due to the superhydrophobicity of the surface of the alumina ceramic material of the present application, the stains on the surface of the alumina ceramic material will be suspended in the water droplets. When using a cleaning gas to clean the surface of the alumina ceramic material, the stains will follow the water droplets and be discharged from the working area, achieving a good cleaning effect on the alumina ceramic material and providing a basis for the research and development of electrostatic chucks. In addition, since the hydrophobic layer on the alumina ceramic material of the present invention is an organic substance, there is no problem of heavy metal pollution caused by using heavy metal sputtering, nor is there any deterioration of electrical / mechanical / thermal properties caused by doping and modifying alumina with other oxides.

[0009] To achieve a better superhydrophobic effect, further, the contact angle between the alumina ceramic material and water > 130°; preferably, the contact angle between the alumina ceramic material and water > 150°.

[0010] Further, the D 50 particle size of the alumina ceramic matrix ≤ 1.5 μm; preferably, the D 50The particle size is greater than or equal to 200 nm and less than or equal to 1.5 μm; preferably, the D of the alumina ceramic matrix 50 The particle size is greater than or equal to 200 nm and less than or equal to 1 μm.

[0011] In the above solution, the alumina ceramic matrix used in the alumina ceramic material of the present invention is granular, and its D 50 The particle size is below 1 μm. On the one hand, when the particle size is small, the pits formed between particles are also relatively small, and it is difficult for liquid to penetrate into the pits, resulting in some residual air being trapped in the pits. The residual air and the rough surface contact water together to form a contact surface, thereby improving the hydrophobicity of the surface. On the other hand, the particle size and morphology of the powder will affect the amount of organic additives used in the preparation of the slurry, thereby affecting the rheology, stability, uniformity of the slurry and the quality of the green film after film formation, and ultimately affecting the sintering and properties of the ceramic. Generally, the smaller the particles, the better the sintering activity and the lower the sintering temperature, which can make the ceramic more dense. However, if the particles are too small, the required organic additives increase, which is not conducive to debinding and sintering. Therefore, a more suitable D 50 Particle size range of the alumina ceramic matrix should be selected.

[0012] According to the second aspect of the present invention, the present invention provides a method for preparing the above alumina ceramic material, including the following steps:

[0013] Step (1): Prepare an alumina ceramic matrix;

[0014] Step (2): Perform surface hydroxylation treatment on the prepared alumina ceramic matrix;

[0015] Step (3): Graft-modify the surface of the alumina ceramic matrix after surface hydroxylation treatment with a surface modifier to form a hydrophobic layer on the surface of the alumina ceramic matrix;

[0016] Step (4): Wash the alumina ceramic matrix with a hydrophobic layer formed on its surface successively with n-hexane, acetone, and deionized water, and dry it to obtain an alumina ceramic material.

[0017] In the above solution, the preparation method of the alumina ceramic material of the present invention utilizes the characteristic that the surface of the alumina ceramic matrix has active hydroxyl groups, and can graft different groups on the surface of the alumina ceramic matrix. The surface of the alumina ceramic matrix is modified by the surface grafting reaction method. Specifically, a polymer material is connected to the hydroxyl groups on the surface of the alumina ceramic matrix through a chemical reaction, and finally the purpose of superhydrophobicity is achieved. Compared with the use of surfactants and coupling agents, the surface grafting method has greater advantages, greatly improving the stability and hydrophobicity of the alumina ceramic surface. In addition, the polymer surface grafting method also has the characteristics of simple operation, easy control of conditions, low equipment cost, and suitability for industrial production.

[0018] Further, step (3) is specifically as follows:

[0019] Immerse the alumina ceramic substrate after surface hydroxylation treatment into an aqueous solution of polyethyleneimine (PEI), and let it stand for a period of time to form a PEI film on the surface of the alumina ceramic substrate;

[0020] Immerse the alumina ceramic substrate with a PEI film formed on its surface into a n - hexane solution containing a carboxylic acid compound and a dehydrating agent, and react for a period of time to form a hydrophobic layer on the surface of the alumina ceramic substrate; Preferably, the reaction time is 12 - 36 h.

[0021] In the above - mentioned solution, in the preparation method of the alumina ceramic material of the present invention, PEI is a cationic polymer, which can be adsorbed on the surface - hydroxylated alumina ceramic substrate through hydrogen bonds and van der Waals forces and is not easily detached. The carboxylic acid compound consists of a carboxyl group and a carbon chain. The long carbon chain ensures the hydrophobicity of the material, and the carboxyl group reacts with the amino group in PEI, making it have a high binding force with PEI. In order to ensure the complete reaction of PEI and the carboxylic acid compound, a dehydrating agent is added in the modification process. The dehydrating agent first reacts with the carboxylic acid compound, and its reaction product then reacts with the amino group on PEI. After the reaction is completed, the main chain of the dehydrating agent is discharged as a by - product.

[0022] Further, in step (3), the carboxylic acid compound is selected from one or more of palmitic acid, stearic acid or arachidic acid.

[0023] In the above - mentioned solution, palmitic acid, stearic acid and arachidic acid are homologues, and in terms of composition, they are all composed of a carboxyl group and a carbon chain. The long carbon chain ensures the hydrophobicity of the material, and the carboxyl group reacts with the amino group in PEI, making it have a higher binding force with PEI.

[0024] Further, in step (3), in the n - hexane solution, the concentration of the carboxylic acid compound is 2 - 5 mmol / L.

[0025] In the above - mentioned solution, by selecting an appropriate concentration of the carboxylic acid compound, the reaction efficiency with the amino group in PEI can be improved.

[0026] Further, in step (3), the dehydrating agent is N, N'-dicyclohexylcarbodiimide; and / or, in the n - hexane solution, the concentration of the dehydrating agent is 1 - 5 mmol / L, preferably 3 mmol / L.

[0027] In the above - mentioned solution, by selecting an appropriate type of dehydrating agent, the reaction between PEI and the carboxylic acid compound can be accelerated to completion faster, and the surface modification efficiency can be further improved. By reasonably limiting the concentration of the dehydrating agent, the surface modification efficiency can be further improved.

[0028] Further, in step (3), the concentration of the PEI aqueous solution is 0.2 - 0.4 wt%, preferably 0.3 wt%.

[0029] and / or, the standing time ≥ 20 min;

[0030] and / or, in step (3), the alumina ceramic substrate after surface hydroxylation treatment is immersed in the PEI aqueous solution. After standing for a period of time, it is washed with water and then dried to form a PEI film on the surface of the alumina ceramic substrate; preferably, the drying temperature is 30 - 50 °C and the time is 10 - 14 h.

[0031] In the above solution, by reasonably limiting the concentration of the PEI aqueous solution and the standing time, the surface of the alumina ceramic substrate can be completely coated with PEI, so as to achieve a more comprehensive surface modification purpose and improve the efficiency of surface modification.

[0032] Further, step (1) specifically includes the following steps:

[0033] Mix the alumina powder, solvent and binder evenly to obtain a slurry; cast the obtained slurry at 50 - 70 °C to obtain a cast film tape; preferably, the solvent includes at least one of water, toluene, and alcohol; the addition amount of the solvent is 30 - 50 wt% of the mass of the alumina powder; the binder is at least one of PVB, ethyl cellulose, and PVA; the addition amount of the binder is 5 - 15 wt% of the mass of the alumina powder;

[0034] Stack and hot isostatically press multiple cast film tapes, and then sinter at 1500 - 1650 °C for 1 - 4 h to obtain the alumina ceramic substrate; preferably, the thickness of the doctor blade used for casting is 100 μm - 600 μm; the temperature of the hot isostatic pressing is 50 - 85 °C and the pressure is 30 - 70 MPa.

[0035] In the above solution, by setting a reasonable preparation process, an alumina ceramic substrate with high strength can be prepared, and the strength is specifically 400 - 500 Mpa.

[0036] Further, in step (2), the alumina ceramic substrate is subjected to surface hydroxylation treatment using a mixed solvent containing hydrogen peroxide and sulfuric acid; preferably, the volume ratio of hydrogen peroxide to sulfuric acid is (2 - 4) : (6 - 8); the surface hydroxylation treatment time is at least 12 h, and the drying form of blowing dry the surface with nitrogen is used to remove surface impurities.

[0037] In the above solution, the obtained alumina ceramic matrix is subjected to surface hydroxylation pre-modification, which can make the surface of the alumina ceramic matrix rich in hydroxyl groups and increase the bonding force between the ceramic matrix and the surface organic substance. The solvent used for the surface hydroxylation of the ceramic matrix is a mixed solution of hydrogen peroxide / sulfuric acid. By limiting the volume ratio of hydrogen peroxide to sulfuric acid and the surface hydroxylation treatment time within reasonable range values, the efficiency of surface modification can be improved, and the bonding force between the ceramic matrix and the surface organic substance can be increased more effectively.

[0038] A self-cleaning alumina ceramic material of the present invention forms a hydrophobic layer on the surface of the alumina ceramic matrix through hydrophobic modification, enabling the surface of the alumina ceramic material to be in a superhydrophobic state, and achieving the self-cleaning effect without affecting the electrical / mechanical / thermal properties of the material.

[0039] A preparation method of a self-cleaning alumina ceramic material of the present invention uses polyethyleneimine and palmitic acid / stearic acid / arachidic acid to perform surface modification on the surface-hydroxylated alumina ceramic matrix to achieve the superhydrophobic purpose. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic diagram of the cleaning effect on the surface of the existing alumina ceramic in the background art;

[0042] Figure 2 It is a schematic diagram of the cleaning effect on the surface of a self-cleaning alumina ceramic material of the present invention;

[0043] Figure 3 It is a reaction mechanism diagram in the preparation method of a self-cleaning alumina ceramic material according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0045] In the following examples, palmitic acid / stearic acid (STA) / arachidic acid were used to modify the surface hydroxylated alumina ceramic matrix samples with polyethyleneimine (PEI). Taking advantage of the characteristics of PEI as a cationic polymer, PEI can be adsorbed on any surface hydroxylated alumina ceramic matrix through hydrogen bonds and van der Waals forces. On this basis, the alumina ceramic matrix samples attached with PEI were respectively immersed in the n-hexane dilute solutions of palmitic acid / STA / arachidic acid, so that the carboxyl groups on the molecular chains reacted with the amino groups in the PEI molecules, ultimately achieving a hydrophobic effect. The specific reaction mechanism is as Figure 3 shown.

[0046] Example 1

[0047] This example provides a self-cleaning alumina ceramic material, which includes an alumina ceramic matrix and a hydrophobic layer formed on the surface of the alumina ceramic matrix.

[0048] The preparation method of the alumina ceramic material in this example is as follows:

[0049] (1) The alumina powder was placed in a three-dimensional mixer and mixed evenly, then alcohol and binder (PVB) were added. The slurry was placed in a casting machine and cast within the range of 50 - 70 °C to obtain a cast film tape. The addition amount of alcohol was 80% of the alumina powder, and the addition amount of the binder was 20% of the alumina powder.

[0050] (2) The above cast film tape was subjected to laminated hot isostatic pressing. The hot isostatic pressing temperature was 70 °C, and the hot isostatic pressing pressure was 40 MPa. Then it was sintered at 1600 °C for 4 h to obtain a high-strength alumina ceramic matrix, and the strength was specifically 450 Mpa.

[0051] (3) The alumina ceramic matrix was subjected to surface hydroxylation treatment. After the alumina ceramic matrix was ultrasonically cleaned, it was placed in a mixed solution of 70% concentrated sulfuric acid and 30% H2O2 and soaked for 24 h, then rinsed with distilled water multiple times and dried with nitrogen to remove the impurities attached to the surface.

[0052] (4) The surface hydroxylated alumina ceramic matrix was immersed in a 0.3 wt% aqueous solution of PEI and allowed to stand for 1 h, and then washed with a large amount of distilled water. The washed sample was placed in a constant temperature environment of 40 °C and dried for 24 h to form a PEI film on the surface of the alumina ceramic matrix. Among them, the 0.3 wt% aqueous solution of PEI was obtained by diluting the PEI with a molecular weight of 25000 and a concentration of 30 wt% with water to 0.3 wt%.

[0053] (5) Immerse the dried sample in a hexane solution containing palmitic acid and N,N'-dicyclohexylcarbodiimide (DCC) and react for 24 h to form a hydrophobic layer on the surface of the alumina ceramic substrate. Among them, the concentration of palmitic acid is 2 mmol / L, and the concentration of DCC is 3 mmol / L.

[0054] (6) Take out the sample, wash it successively with hexane, acetone, and deionized water, and dry it to obtain the final alumina ceramic material with superhydrophobic performance.

[0055] The performance test results of the finally obtained alumina ceramic material are shown in Table 1.

[0056] Example 2

[0057] The difference from Example 1 is that in step (5), the concentration of palmitic acid is 3 mmol / L.

[0058] Example 3

[0059] The difference from Example 1 is that in step (5), the concentration of palmitic acid is 4 mmol / L.

[0060] Example 4

[0061] The difference from Example 1 is that in step (5), the concentration of palmitic acid is 5 mmol / L.

[0062] Example 5

[0063] The difference from Example 1 is that in step (5), stearic acid is used instead of palmitic acid, and the concentration of stearic acid is 2 mmol / L.

[0064] Example 6

[0065] The difference from Example 5 is that in step (5), the concentration of stearic acid is 3 mmol / L.

[0066] Example 7

[0067] The difference from Example 5 is that in step (5), the concentration of stearic acid is 4 mmol / L.

[0068] Example 8

[0069] The difference from Example 5 is that in step (5), the concentration of stearic acid is 5 mmol / L.

[0070] Example 9

[0071] It is different from Example 1 in that: in step (5), arachidic acid is used to replace palmitic acid, and the concentration of arachidic acid is 2 mmol / L.

[0072] Example 10

[0073] It is different from Example 9 in that: in step (5), the concentration of arachidic acid is 3 mmol / L.

[0074] Example 11

[0075] It is different from Example 9 in that: in step (5), the concentration of arachidic acid is 4 mmol / L.

[0076] Example 12

[0077] It is different from Example 9 in that: in step (5), the concentration of arachidic acid is 5 mmol / L.

[0078] Example 13

[0079] It is different from Example 1 in that: in step (5), the concentration of DCC is 1 mmol / L.

[0080] Example 14

[0081] It is different from Example 1 in that: in step (5), the concentration of DCC is 5 mmol / L.

[0082] Example 15

[0083] It is different from Example 6 in that: in step (4), the concentration of the PEI aqueous solution is 0.2 wt%.

[0084] Example 16

[0085] It is different from Example 6 in that: in step (4), the concentration of the PEI aqueous solution is 0.4 wt%.

[0086] Comparative Example 1

[0087] This comparative example provides an alumina ceramic material, which specifically includes the following steps:

[0088] (1) Place the alumina powder in a three-dimensional mixer, mix it evenly, add alcohol and a binder, place the slurry in a casting machine, and cast it in the range of 50 - 70 °C to obtain a cast film tape;

[0089] (2) Subject the above cast film tape to laminated hot isostatic pressing. The hot isostatic pressing temperature is 70 °C, the hot isostatic pressing pressure is 40 MPa, and then sinter it at 1600 °C for 4 h to obtain a high-strength alumina ceramic material.

[0090] The performance test results of the finally obtained alumina ceramic material are shown in Table 1.

[0091] Comparative Example 2

[0092] This comparative example provides an alumina ceramic material, which specifically includes the following steps:

[0093] (1) Place the alumina powder in a three-dimensional mixer, mix it evenly, add alcohol and binder, put the slurry in a casting machine, and cast it in the range of 50-70 °C to obtain a cast film tape.

[0094] (2) Stack and hot isostatically press the above cast film tape. The hot isostatic pressing temperature is 70 °C, the hot isostatic pressing pressure is 40 MPa, and then sinter it at 1600 °C for 4 h to obtain a high-strength alumina composite ceramic material.

[0095] (3) Perform surface hydroxylation treatment on the ceramic. After ultrasonic cleaning the ceramic, place it in a mixed solution of 70% concentrated sulfuric acid and 30% H2O2 by volume and soak it for 24 h, then rinse it with distilled water multiple times and dry it with nitrogen to remove impurities attached to the surface.

[0096] (4) Immerse the ceramic sample after surface hydroxylation treatment in a 0.3 wt% aqueous solution of PEI, let it stand for 1 h to form a PEI film on the ceramic surface, and then wash it with a large amount of distilled water. Place the washed sample in a constant temperature environment of 40 °C and dry it for 24 h.

[0097] (5) Take out the sample, wash it successively with n-hexane, acetone, and deionized water, and dry it to obtain the alumina ceramic material.

[0098] The performance test results of the finally obtained alumina ceramic material are shown in Table 1 for Comparative Example 3

[0099] The difference from Example 1 is that in step (5), acetic acid is used instead of palmitic acid.

[0100] Table 1 Performance table of alumina ceramic materials in examples and comparative examples

[0101]

[0102]

[0103] As can be seen from Table 1, the contact angle between the alumina ceramic material prepared by the preparation method of the present invention and water is >110°, which has superhydrophobic properties and can improve the self-cleaning performance of the alumina ceramic material. Further, when the content of palmitic acid / stearic acid / arachidic acid is small, the increase in the content of polyethyleneimine (PEI) has no obvious effect on the performance of the sample, indicating that coating a single PEI film on the surface of the alumina ceramic cannot play a hydrophobic role. In addition, since PEI plays a role in coating the surface of the alumina ceramic in the present invention, when the content of PEI reaches 0.3 wt%, the surface of the alumina ceramic is relatively completely coated with PEI, and on this basis, the performance cannot be improved by further increasing the content of PEI. In addition, by comparing the optimal performance of palmitic acid / stearic acid / arachidic acid, it is found that the length of a single carbon chain has an obvious effect on the hydrophobic performance. The longer the carbon chain, the better the hydrophobic performance.

[0104] In summary, when the PEI concentration in the system is 0.3 wt% and the palmitic acid concentration is 4 mmol / L, PEI can relatively completely coat the surface of the alumina ceramic, and the reaction between palmitic acid and PEI is relatively sufficient. Finally, the sample presents the highest water contact angle (155.6°), which meets the definition of a superhydrophobic surface. Therefore, Example 11 obtains the best comprehensive performance.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-cleaning alumina ceramic material, characterized in that, It includes an alumina ceramic matrix and a hydrophobic layer formed on the surface of the alumina ceramic matrix. The hydrophobic layer is obtained by surface graft modification of the alumina ceramic matrix; the contact angle between the alumina ceramic material and water > 110°.

2. The alumina ceramic material according to claim 1, characterized in that the contact angle between the alumina ceramic material and water > 130°; preferably, the contact angle between the alumina ceramic material and water > 150°.

3. The alumina ceramic material according to claim 1, characterized in that, The D of the alumina ceramic matrix 50 particle size ≤ 1.5 μm; preferably, the D of the alumina ceramic matrix 50 particle size is greater than or equal to 200 nm and less than or equal to 1 μm.

4. A preparation method of the alumina ceramic material according to any one of claims 1-3, characterized in that, It includes the following steps: Step (1): Prepare the alumina ceramic matrix; Step (2): Perform surface hydroxylation treatment on the prepared alumina ceramic matrix; Step (3): Use a surface modifier to perform surface graft modification on the alumina ceramic matrix after surface hydroxylation treatment, so as to form a hydrophobic layer on the surface of the alumina ceramic matrix; Step (4): Wash the alumina ceramic matrix with a hydrophobic layer on its surface successively with n-hexane, acetone, and deionized water, and dry it to obtain the alumina ceramic material.

5. The preparation method of the alumina ceramic material according to claim 4, characterized in that, Step (3) is specifically as follows: Immerse the alumina ceramic matrix after surface hydroxylation treatment in an aqueous PEI solution, and let it stand for a period of time to form a PEI film on the surface of the alumina ceramic matrix; Immerse the alumina ceramic matrix with a PEI film formed on its surface in a n-hexane solution containing a carboxylic acid compound and a dehydrating agent and react for a period of time to form a hydrophobic layer on the surface of the alumina ceramic matrix.

6. The preparation method according to claim 5, characterized in that, In step (3), the carboxylic acid compound is selected from one or more of palmitic acid, stearic acid, or arachidic acid; And / or, the dehydrating agent is N,N'-dicyclohexylcarbodiimide.

7. The preparation method according to claim 5 or 6, characterized in that, In step (3), in the n-hexane solution, the concentration of the carboxylic acid compound is 2 - 5 mmol / L; And / or, in the n-hexane solution, the concentration of the dehydrating agent is 1 - 5 mmol / L, preferably 3 mmol / L.

8. The preparation method according to claim 5, characterized in that, In step (3), the concentration of the aqueous PEI solution is 0.2 - 0.4 wt%, preferably 0.3 wt%; And / or, the standing time ≥ 20 min; And / or, in step (3), after immersing the alumina ceramic matrix after surface hydroxylation treatment in the aqueous PEI solution and letting it stand for a period of time, wash it with water and then dry it to form a PEI film on the surface of the alumina ceramic matrix; preferably, the drying temperature is 30 - 50 °C and the time is 10 - 14 h.

9. The preparation method according to claim 4, characterized in that, Step (1) specifically includes the following steps: Mix alumina powder, a solvent, and a binder evenly to obtain a slurry; cast the obtained slurry at 50 - 70 °C to obtain a cast film tape; preferably, the solvent includes at least one of water, toluene, and alcohol; the addition amount of the solvent is 30 - 50 wt% of the mass of the alumina powder; the binder is at least one of PVB, ethyl cellulose, and PVA; the addition amount of the binder is 5 - 15 wt% of the mass of the alumina powder; Stack and hot isostatically press multiple cast film tapes, and then sinter at 1500 - 1650 °C for 1 - 4 h to obtain the alumina ceramic matrix; preferably, the thickness of the doctor blade used for casting is 100 μm - 600 μm; the temperature of the hot isostatic pressing is 50 - 85 °C and the pressure is 30 - 70 MPa.

10. The preparation method according to claim 4, characterized in that, In step (2), use a mixed solvent containing hydrogen peroxide and sulfuric acid to perform surface hydroxylation treatment on the alumina ceramic matrix; preferably, the volume ratio of hydrogen peroxide to sulfuric acid is (2 - 4):(6 - 8); The surface hydroxylation treatment time is at least 12 h, and the drying form of blowing dry the surface with nitrogen is adopted to remove surface impurities.

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