Alumina ceramic material and preparation method thereof

Abstract

The invention relates to the technical field of ceramic materials, in particular to an aluminum oxide ceramic material and a preparation method thereof. The aluminum oxide ceramic material comprises a composite aluminum oxide material layer, the composite aluminum oxide material layer comprises modified sheet-shaped or rod-shaped aluminum oxide and granular aluminum oxide, and the modified sheet-shaped or rod-shaped aluminum oxide accounts for 1%-15% of the total weight of the aluminum oxide ceramic material. The granular aluminum oxide accounts for 85-99% of the total weight of the aluminum oxide ceramic material. According to the aluminum oxide ceramic material disclosed by the invention, the bending strength of the aluminum oxide ceramic material can be enhanced by adding the modified sheet-shaped or rod-shaped aluminum oxide, and the obtained aluminum oxide ceramic material is high in compactness after the modified sheet-shaped or rod-shaped aluminum oxide and the granular aluminum oxide are compounded for use; the aluminum oxide ceramic material has an adjustable dielectric constant, lower dielectric loss and higher bending strength, and can be applied to an electrostatic chuck with higher bending strength on the ceramic material.

Description

Technical Field

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

[0002] In recent years, the integration level of chips has been continuously improved and the feature size has been continuously reduced. To meet the improvement of the integration level and the reduction of the feature size of integrated circuits (ICs), 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 detection. To ensure the manufacturing quality of ICs, it is necessary to ensure that the silicon wafers remain absolutely stable during the transfer process between process equipment, and at the same time, it is also necessary to ensure that the silicon wafers will not warp, deform or shift under the action of the 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, and each procedure needs to ensure the stable fixation of the silicon wafer, which requires the electrostatic chuck to have excellent corrosion and wear resistance. In addition, in addition to excellent corrosion and wear resistance, mechanical properties are also crucial for improving the bearing capacity and reliability of the electrostatic chuck. In most studies on electrostatic chuck materials, relevant researchers have carried out a large number of studies on the structural design, dielectric properties, wear and corrosion resistance of the electrostatic chuck, while few scholars have paid attention to the mechanical properties of electrostatic chuck materials. The manufacturing method of the electrostatic chuck generally uses alumina ceramic as the dielectric, then forms a thin film electrode on the ceramic dielectric, and finally forms another layer of dielectric through a sintering process. With the continuous development of technology, mechanical properties may become the key factor restricting the application of alumina ceramic in electrostatic chucks.

[0005] At present, two methods are usually used to strengthen the mechanical properties of alumina, namely composite doping modification and adjustment of the sintering process. Alumina is usually compounded with high-strength components such as ZrO2, TiC, and SiC to obtain a composite material with better mechanical strength than the alumina body. However, since the electrostatic chuck is usually in a high-temperature environment, the thermal expansion coefficient of the second phase in the composite component usually does not match that of the alumina matrix, resulting in interface problems, directly leading to crack generation and greatly affecting the service life of the electrostatic chuck. In addition, ultra-high-density ceramics can be obtained by hot pressing / gas pressure sintering of alumina, which has extremely high mechanical properties. However, due to price and size limitations, it is not suitable for industrial mass production, restricting its application. Summary of the Invention

[0006] The present invention provides an alumina ceramic material and a preparation method thereof to solve the problems such as interface problems and low cost performance easily caused by the mismatch between the thermal expansion coefficient of the second phase in the existing alumina ceramic material for electrostatic chucks and the thermal expansion coefficient of the alumina matrix.

[0007] According to the first aspect of the present invention, the present invention provides an alumina ceramic material, including a composite alumina material layer. The composite alumina material layer includes modified flaky or rod-shaped alumina and granular alumina. The modified flaky or rod-shaped alumina accounts for 1%-15% of the total weight of the alumina ceramic material, and the granular alumina accounts for 85%-99% of the total weight of the alumina ceramic material.

[0008] In the above solution, an alumina ceramic material of the present invention includes a composite alumina material layer. The composite alumina material layer includes modified flaky or rod-shaped alumina and granular alumina. Generally, the flexural strength of the material is reflected by the ease of crack propagation. By adding modified flaky or rod-shaped alumina, when crack propagation occurs and encounters the modified flaky or rod-shaped alumina, the crack will bypass the flaky or rod-shaped alumina or directly penetrate through the flaky or rod-shaped alumina, increasing the crack propagation path and consuming more energy, which is manifested as an increase in flexural strength. At the same time, both the modified flaky or rod-shaped alumina and the granular alumina are alumina, so there is no interface problem that occurs after sintering due to a too large difference in thermal expansion coefficients. Moreover, the sintering temperature of the flaky or rod-shaped alumina is not much different from the sintering temperature of the granular alumina powder. The alumina ceramic material obtained by compounding the two has a high density, enabling the alumina ceramic material to have an adjustable dielectric constant, lower dielectric loss, and higher flexural strength, and can be applied to electrostatic chucks with relatively high flexural strength for ceramic materials. Further, by limiting the weight percentages of the modified flaky or rod-shaped alumina and the granular alumina in the total weight of the alumina ceramic material within a reasonable range, the modified flaky or rod-shaped alumina and the granular alumina achieve a better synergistic effect, making the alumina ceramic material obtained by compounding the two have a higher density, higher flexural strength, adjustable dielectric constant, and lower dielectric loss. For example, the room temperature flexural strength is as high as 570 MPa, the dielectric constant can be 10 - 11, and the dielectric loss is less than 3×10 -4 . When the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the alumina ceramic material is less than 1%, when crack propagation occurs and encounters the modified flaky or rod-shaped alumina, the crack will bypass the flaky or rod-shaped alumina or directly penetrate through the flaky or rod-shaped alumina, but the increase in the crack propagation path is not obvious and the consumed energy is not large enough, resulting in an insignificant increase in flexural strength; when the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the alumina ceramic material is higher than 20%, it will cause defects such as pores inside the material, resulting in incomplete sintering of the material and thus a decrease in flexural strength and deterioration of dielectric properties.

[0009] Further, the modified flaky or rod-shaped alumina is obtained by modifying the flaky or rod-shaped alumina with a coupling agent;

[0010] Preferably, the coupling agent is polysilazane; and / or, the dosage of the coupling agent is 1% - 1.5% of the flaky or rod-shaped alumina.

[0011] In the above solution, the modified flaky or rod-shaped alumina is obtained by modifying the flaky or rod-shaped alumina with a coupling agent. Through modification, the hydrophilicity of the surface of the flaky or rod-shaped alumina can be changed, the bonding force between the flaky or rod-shaped alumina and the granular alumina can be increased, the interfacial pores can be reduced, and the purpose of reducing loss and increasing the thermal conductivity can be achieved. Further, by selecting a suitable type of coupling agent and / or controlling the amount of the coupling agent within a reasonable range value, a better modification effect can be achieved, and the bonding force between the flaky or rod-shaped alumina and the granular alumina can be further increased. Furthermore, the coupling agent used for modification is polysilazane, and polysilazane can improve the surface modification of the flaky or rod-shaped alumina, and further reduce the porosity of the composite material while strengthening the bonding force between the two phases.

[0012] Further, the radial dimension of the modified flaky or rod-shaped alumina is 5 μm - 50 μm, and the thickness is 0.1 μm - 2 μm, and the D 50 particle size of the granular alumina is below 1 μm;

[0013] and / or, the D 50 particle size of the alumina ceramic material is 200 nm - 1.5 μm, preferably below 1 μm.

[0014] In the above solution, since 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, by limiting the size of the modified flaky or rod-shaped alumina and the D 50 particle size of the granular alumina, it is beneficial to the sintering and performance improvement of the alumina ceramic material, enabling the modified flaky or rod-shaped alumina and the granular alumina to achieve a better synergistic effect, making the alumina ceramic material obtained by compounding the two more dense, and enabling the composite material to have higher flexural strength, adjustable dielectric constant and lower dielectric loss. Limiting the D 50 particle size of the alumina ceramic material within a reasonable range value enables the composite material to have higher flexural strength, adjustable dielectric constant and lower dielectric loss.

[0015] Further, it further includes a single alumina material layer, and the single alumina material layer is composed of granular alumina; the composite alumina material layer is disposed on one side surface of the single alumina material layer or between two single alumina material layers.

[0016] In the above scheme, if a pure composite alumina material layer is used, although the mechanical properties of the alumina ceramic material can be improved, the addition of modified flaky or rod-shaped alumina may lead to a decrease in dielectric properties. Although the single alumina material layer has excellent dielectric properties, its bending strength is low. The alumina ceramic material of the above scheme includes not only the composite alumina material layer, but also a single alumina material layer composed of granular alumina. The composite alumina material layer is arranged on one side surface of the single alumina material layer or between two single alumina material layers, so that the entire alumina ceramic material can form a gradient structure on the component, which is beneficial to improving the bending strength of the alumina ceramic material, and can make the obtained alumina ceramic material have both high bending strength and excellent dielectric properties.

[0017] Furthermore, the alumina ceramic material includes a single alumina material layer and a plurality of composite alumina material layers, and the plurality of composite alumina material layers are stacked in sequence on one side surface of the single alumina material layer, and along the direction away from the single alumina material layer, in the plurality of composite alumina material layers, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer increases successively, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer decreases successively.

[0018] In the above scheme, the entire alumina ceramic material can form a better gradient structure in terms of components, which is more conducive to improving the bending strength of the alumina ceramic material, and can make the obtained alumina ceramic material have both high bending strength and excellent dielectric properties.

[0019] Further, the alumina ceramic material includes two layers of single alumina material layers and a multilayer composite alumina material layer, the multilayer composite alumina material layer is arranged between the two layers of the single alumina material layers, and along the direction from one layer of the single alumina material layer to the other layer of the single alumina material layer, in the multilayer composite alumina material layer, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer first increases and then decreases, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer first decreases and then increases;

[0020] Preferably, the multilayer composite alumina material layer has a gradient symmetrical structure; along the direction from one layer of the single alumina material layer to another layer of the single alumina material layer, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer first increases by equal amounts and then decreases by equal amounts, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer first decreases by equal amounts and then increases by equal amounts.

[0021] In the above solution, the alumina ceramic material includes two single alumina material layers and multiple composite alumina material layers. The multiple composite alumina material layers are arranged between the two single alumina material layers, enabling the entire alumina ceramic material to form a sandwich-type gradient structure in terms of composition, which is more conducive to improving the flexural strength of the alumina ceramic material and making the obtained alumina ceramic material have both high flexural strength and excellent dielectric properties.

[0022] Furthermore, the alumina ceramic material includes two single alumina material layers and seven composite alumina material layers. Along the direction from one single alumina material layer to the other single alumina material layer, among the multiple composite alumina material layers, the weight percentages of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer are 5%, 10%, 15%, 20%, 15%, 10%, and 5% in sequence, and the weight percentages of the granular alumina in the total weight of the composite alumina material layer are 95%, 90%, 85%, 80%, 85%, 90%, and 95% in sequence.

[0023] In the above solution, for the sandwich-type gradient structure, further by controlling the number of layers of the multiple composite alumina material layers and the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer within a reasonable range value, it is more conducive to improving the flexural strength of the alumina ceramic material and making the obtained alumina ceramic material have both high flexural strength and excellent dielectric properties.

[0024] Furthermore, it is formed by laminating multiple composite alumina material layers; along the thickness direction of the alumina ceramic material, from one end of the alumina ceramic material to the other end, among the multiple composite alumina material layers, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer first increases in sequence and then decreases in sequence, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer first decreases in sequence and then increases in sequence;

[0025] Preferably, the multiple composite alumina material layers have a gradient symmetric structure; along the thickness direction of the alumina ceramic material, from one end of the alumina ceramic material to the other end, among the multiple composite alumina material layers, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer first increases equally in sequence and then decreases equally in sequence, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer first decreases equally in sequence and then increases equally in sequence.

[0026] In the above solution, for the non-sandwich type gradient structure, by restricting the weight percentage of modified flaky or rod-shaped alumina and granular alumina in the multi-layer composite alumina material layer to a reasonable trend, it is more conducive to improving the flexural strength of the alumina ceramic material, and the obtained alumina ceramic material can have both high flexural strength and excellent dielectric properties.

[0027] According to the second aspect of the present invention, the present invention also provides a preparation method of the above alumina ceramic material, including the following steps:

[0028] After uniformly mixing the modified flaky or rod-shaped alumina and granular alumina, mix them uniformly with a solvent and a binder to obtain a slurry; cast the obtained slurry to obtain a cast film tape;

[0029] Perform hot isostatic pressing on the obtained cast film tape, and then sinter it to obtain an alumina ceramic material.

[0030] In the above solution, in the preparation method of the alumina ceramic material, first mix the modified flaky or rod-shaped alumina, granular alumina with a solvent and a binder to obtain a slurry, and then use the casting process to cast the slurry, so that under the dual action of the shear force of the doctor blade and gravity, the modified flaky or rod-shaped alumina is laid flat at the bottom of the film tape to form a cast film tape containing flaky or rod-shaped alumina. According to the design of different alumina ceramic materials, the ratio of the modified flaky or rod-shaped alumina and granular alumina can be adjusted to form a cast film tape with different contents of flaky or rod-shaped alumina, so that the flaky or rod-shaped alumina shows a regular arrangement. Then, wait for the film tape to dry and perform isostatic pressing. Strengthen the layered arrangement of the flaky alumina through laminated isostatic pressing to obtain an alumina ceramic material with both high flexural strength and excellent dielectric properties.

[0031] Furthermore, the solvent is selected from at least one of water, toluene, and alcohol;

[0032] And / or, the binder is selected from at least one of PVB, ethyl cellulose, and PVA; the dosage of the binder is 5%-15% of the sum of the weights of the modified flaky or rod-shaped alumina and granular alumina;

[0033] And / or, the temperature used in the casting process is 50°C - 70°C, and the thickness of the doctor blade is 100μm - 600μm;

[0034] And / or, the temperature used in the hot isostatic pressing process is 50°C - 85°C, and the pressure is 30MPa - 70MPa;

[0035] And / or, the sintering temperature is 1500°C - 1650°C, and the time is 1h - 4h.

[0036] In the above solution, by selecting a solvent of a suitable type, a binder of a suitable type, using a binder amount within a suitable range, and controlling the temperature and doctor blade thickness of the casting process, the temperature and pressure of hot isostatic pressing, and the sintering temperature and time, the structure of the prepared alumina ceramic material can be made more stable, and it has excellent bending properties and dielectric properties.

[0037] An alumina ceramic material of the present invention includes a composite alumina material layer. The composite alumina material layer includes modified flaky or rod-shaped alumina and granular alumina. By adding the modified flaky or rod-shaped alumina, the bending strength of the alumina ceramic material can be enhanced. At the same time, both the modified flaky or rod-shaped alumina and the granular alumina are alumina, so there is no interface problem that occurs after sintering due to a too large difference in thermal expansion coefficients, and the sintering temperature of the flaky or rod-shaped alumina is not much different from the sintering temperature of the granular alumina powder. The alumina ceramic material obtained by compounding the two has a high density, enabling the alumina ceramic material to have an adjustable dielectric constant, lower dielectric loss, and higher bending strength, and can be applied to electrostatic chucks with relatively high bending strength for ceramic materials. The alumina ceramic material of the present invention has a low cost and is easy to mass-produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a schematic structural diagram of an alumina ceramic material according to Embodiment 1 of the present invention;

[0040] Figure 2 It is an SEM image of the modified flaky alumina used in an alumina ceramic material according to Embodiment 1 of the present invention;

[0041] Figure 3 It is a schematic structural diagram of an alumina ceramic material according to Embodiment 5 of the present invention;

[0042] Figure 4 It is a schematic structural diagram of an alumina ceramic material according to Embodiment 6 of the present invention;

[0043] Figure 5 It is a schematic structural diagram of an alumina ceramic material according to Embodiment 8 of the present invention;

[0044] Figure 6 It is a schematic structural diagram of an alumina ceramic material according to Embodiment 9 of the present invention;

[0045] Figure 7 Schematic structural diagram of an alumina ceramic material according to Embodiment 10 of the present invention;

[0046] Figure 8 Schematic structural diagram of an alumina ceramic material according to Embodiment 11 of the present invention;

[0047] Figure 9 SEM image of a partial cross-section of a composite alumina material layer in an alumina ceramic material according to Embodiment 11 of the present invention;

[0048] Figure 10 Schematic structural diagram of an alumina ceramic material according to Embodiment 13 of the present invention;

[0049] Figure 11 Schematic structural diagram of an alumina ceramic material according to Embodiment 15 of the present invention;

[0050] Figure 12 Schematic structural diagram of an alumina ceramic material according to Embodiment 17 of the present invention;

[0051] Figure 13 Weibull distribution diagram of the flexural strength of the alumina ceramic materials of Examples 1-4 and Comparative Examples 1-2;

[0052] Figure 14 Weibull distribution diagram of the flexural strength of the alumina ceramic materials of Examples 5-12.

[0053] Reference numerals: 1: composite alumina material layer; 11: first composite alumina material layer; 12: second composite alumina material layer; 13: third composite alumina material layer; 14: fourth composite alumina material layer; 15: fifth composite alumina material layer; 16: sixth composite alumina material layer; 17: seventh composite alumina material layer; 2: single alumina material layer. Detailed Description of the Invention

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, 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 based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] Example 1

[0056] This example provides an alumina ceramic material, as Figure 1As shown in the figure, it includes a composite alumina material layer 1. The composite alumina material layer 1 includes modified flaky alumina and granular alumina. Among them, the modified flaky alumina accounts for 1% of the total weight of the alumina ceramic material, and the granular alumina accounts for 99% of the total weight of the alumina ceramic material. The modified flaky alumina is obtained by placing flaky alumina in a polysilazane solution with a concentration of 10%, where the total amount of polysilazane is 1 wt% of the flaky alumina, magnetically stirring for 5 h, then filtering, and drying at 120 °C. The microscopic morphology of the modified flaky alumina is as Figure 2 shown, its radial dimension is 11.3 μm, and its thickness is 1.3 μm. The D 50 particle size of the granular alumina is 400 nm.

[0057] The preparation method of the alumina ceramic material in this embodiment includes the following steps:

[0058] (1) Mix the modified flaky alumina and granular alumina according to a weight ratio of 1:99, add alcohol as the ball milling medium, ball mill for 10 h, and then dry at 150 °C to obtain a mixed powder.

[0059] (2) Place the above mixed powder in a three-dimensional mixer and mix evenly, then add alcohol and a binder (PVB). The weight ratio of the mixed powder, alcohol, and binder is 50:40:10. The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film tape.

[0060] (3) Stack and hot isostatically press the above cast film tape. The hot isostatic pressing temperature is 75 °C, and the hot isostatic pressing pressure is 70 MPa. Then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina ceramic material. The process parameters are listed in Table 1, and the performance test results of the finally obtained capacitor material are shown in Table 2.

[0061] Example 2

[0062] The difference from Example 1 is that:

[0063] This example provides an alumina ceramic material. In the composite alumina material layer, the modified flaky alumina accounts for 5% of the total weight of the alumina ceramic material, and the granular alumina accounts for 95% of the total weight of the alumina ceramic material.

[0064] In step (1) of the preparation method of the alumina ceramic material in this example, the modified flaky alumina and granular alumina are mixed according to a weight ratio of 5:95, add alcohol as the ball milling medium, ball mill for 10 h, and then dry at 150 °C to obtain a mixed powder.

[0065] Example 3

[0066] The difference from Example 1 is that:

[0067] This embodiment provides an alumina ceramic material. In the composite alumina material layer, the modified flaky alumina accounts for 10% of the total weight of the alumina ceramic material, and the granular alumina accounts for 90% of the total weight of the alumina ceramic material.

[0068] Step (1) of the preparation method of the alumina ceramic material in this embodiment is to mix the modified flaky alumina and the granular alumina according to a weight ratio of 10:90, add alcohol as the ball milling medium, ball mill for 10 h, and then dry at 150 °C to obtain a mixed powder.

[0069] Example 4

[0070] The difference from Example 1 is as follows:

[0071] This embodiment provides an alumina ceramic material. In the composite alumina material layer, the modified flaky alumina accounts for 15% of the total weight of the alumina ceramic material, and the granular alumina accounts for 85% of the total weight of the alumina ceramic material.

[0072] Step (1) of the preparation method of the alumina ceramic material in this embodiment is to mix the modified flaky alumina and the granular alumina according to a weight ratio of 15:85, add alcohol as the ball milling medium, ball mill for 10 h, and then dry at 150 °C to obtain a mixed powder.

[0073] Example 5

[0074] The difference from Example 1 is as follows:

[0075] This embodiment provides an alumina ceramic material, as Figure 3 shown, which includes a single alumina material layer 2 and two composite alumina material layers 1 (the first composite alumina material layer 11 and the second composite alumina material layer 12). The two composite alumina material layers are arranged on one side surface of the single alumina material layer 2. And along the direction away from the single alumina material layer 2, in the two composite alumina material layers 1, the weight percentage of the modified flaky alumina in the total weight of the composite alumina material layer increases in sequence, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer decreases in sequence. Specifically, in the first composite alumina material layer 11, the weight percentage of the modified flaky alumina in the total weight of the first composite alumina material layer 11 is 5%, and the weight percentage of the granular alumina in the total weight of the first composite alumina material layer 11 is 95%. In the second composite alumina material layer 12, the weight percentage of the modified flaky alumina in the total weight of the second composite alumina material layer 12 is 10%, and the weight percentage of the granular alumina in the total weight of the second composite alumina material layer 12 is 90%.

[0076] The preparation method of the alumina ceramic material in this embodiment includes the following steps:

[0077] (1) Mix the modified flaky alumina and granular alumina according to the weight ratios of 0:100, 5:95, and 10:90 respectively. Add alcohol as the ball-milling medium, and after ball-milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0078] (2) Place the above-mentioned mixed powders in a three-dimensional mixer and mix them evenly. Then add alcohol and a binder (PVB). The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film tape.

[0079] (3) Stack the cast film tapes with 0 wt% of the modified flaky alumina content. On this basis, continue to stack the cast film tapes with 5 wt% of the modified flaky alumina content, and then continue to stack the cast film tapes with 10 wt% of the modified flaky alumina content. At this time, it should be noted that the stacking heights of the two groups of cast film tapes should be the same, and the thickness of each component stack should not be less than 1.4 mm, thus completing the composition gradient design.

[0080] (4) Perform hot isostatic pressing on the above-mentioned stacked cast film tapes. The hot isostatic pressing temperature is 75 °C, and the hot isostatic pressing pressure is 70 MPa. Then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0081] Example 6

[0082] The difference from Example 5 is as follows:

[0083] This example provides an alumina ceramic material, as Figure 4 shown, which includes a single alumina material layer 2 and four composite alumina material layers 1 (the first composite alumina material layer 11, the second composite alumina material layer 12, the third composite alumina material layer 13, and the fourth composite alumina material layer 14). Specifically, in the first composite alumina material layer 11, the weight percentage of the modified flaky alumina in the total weight of the first composite alumina material layer 11 is 5%, and the weight percentage of the granular alumina in the total weight of the first composite alumina material layer 11 is 95%. In the second composite alumina material layer 12, the weight percentage of the modified flaky alumina in the total weight of the second composite alumina material layer 12 is 10%, and the weight percentage of the granular alumina in the total weight of the second composite alumina material layer 12 is 90%. In the third composite alumina material layer 13, the weight percentage of the modified flaky alumina in the total weight of the third composite alumina material layer 13 is 15%, and the weight percentage of the granular alumina in the total weight of the third composite alumina material layer 13 is 85%. In the fourth composite alumina material layer 14, the weight percentage of the modified flaky alumina in the total weight of the fourth composite alumina material layer 14 is 20%, and the weight percentage of the granular alumina in the total weight of the fourth composite alumina material layer 14 is 80%.

[0084] The preparation method of the alumina ceramic material in this embodiment includes the following steps:

[0085] (1) Mix the modified flaky alumina and granular alumina respectively according to the weight ratios of 0:100, 5:95, 10:90, 15:85, 20:80, add alcohol as the ball milling medium, and after ball milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0086] (2) Place the above-mentioned mixed powders into a three-dimensional mixer respectively, mix them evenly, then add alcohol and binder (PVB), and place the obtained slurry in a casting machine to cast at 60 °C to obtain a cast film tape.

[0087] (3) Stack the cast film tapes with 0 wt% of the modified flaky alumina content, and then continue to stack the cast film tapes with 5 wt% of the modified flaky alumina content, continue to stack the cast film tapes with 10 wt% of the modified flaky alumina content, continue to stack the cast film tapes with 15 wt% of the modified flaky alumina content, continue to stack the cast film tapes with 20 wt% of the modified flaky alumina content. At this time, it should be noted that the stacking heights of the two groups of cast film tapes should be the same, and the stacking thickness of each component should not be less than 0.84 mm, thus completing the composition gradient design.

[0088] (4) Perform hot isostatic pressing on the stacked cast film tapes, the hot isostatic pressing temperature is 75 °C, the hot isostatic pressing pressure is 70 MPa, and then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0089] Example 7

[0090] The difference from Example 6 is as follows:

[0091] This embodiment provides an alumina ceramic material. In the first composite alumina material layer 11, the weight percentage of the modified flaky alumina in the total weight of the first composite alumina material layer 11 is 10%, and the weight percentage of the granular alumina in the total weight of the first composite alumina material layer 11 is 90%. In the second composite alumina material layer 12, the weight percentage of the modified flaky alumina in the total weight of the second composite alumina material layer 12 is 20%, and the weight percentage of the granular alumina in the total weight of the second composite alumina material layer 12 is 80%.

[0092] The preparation method of the alumina ceramic material in this embodiment includes the following steps:

[0093] (1) Mix the modified flaky alumina and granular alumina respectively according to the weight ratios of 0:100, 10:90, 20:80, add alcohol as the ball milling medium, and after ball milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0094] (2) The above-mentioned mixed powder is respectively placed in a three-dimensional mixer and mixed evenly, then alcohol and binder (PVB) are added. The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film strip.

[0095] (3) After laminating the cast film strips with 0 wt% of modified flaky alumina, on this basis, continue to laminate the cast film strips with 10 wt% of modified flaky alumina, and then continue to laminate the cast film strips with 20 wt% of modified flaky alumina. At this time, it should be noted that the lamination heights of the two groups of cast film strips should be the same, and the lamination thickness of each component should not be less than 1.4 mm, thus completing the composition gradient design.

[0096] (4) The above laminated cast film strips are subjected to hot isostatic pressing at a temperature of 75 °C and a pressure of 70 MPa, and then sintered at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0097] Example 8

[0098] The difference from Example 7 is as follows:

[0099] This example provides an alumina ceramic material, as Figure 5 shown, which includes two layers of single alumina material layer 2 and one layer of composite alumina material layer 1, and one layer of composite alumina material layer 1 is arranged between the single alumina material layers 2. Among them, in the composite alumina material layer 1, the weight percentage of modified flaky alumina in the total weight of the composite alumina material layer 1 is 10%, and the weight percentage of granular alumina in the total weight of the composite alumina material layer 1 is 90%.

[0100] The preparation method of the alumina ceramic material in this example includes the following steps:

[0101] (1) Modified flaky alumina and granular alumina are respectively mixed according to the weight ratio of 0:100, 10:90, 0:100, alcohol is added as the ball milling medium, and after ball milling for 10 h, it is dried at 150 °C to obtain the mixed powder respectively.

[0102] (2) The above-mentioned mixed powder is respectively placed in a three-dimensional mixer and mixed evenly, then alcohol and binder (PVB) are added. The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film strip.

[0103] (3) After laminating the cast film strips with 0 wt% of modified flaky alumina, on this basis, continue to laminate the cast film strips with 10 wt% of modified flaky alumina, and then continue to laminate the cast film strips with 0 wt% of modified flaky alumina to form a sandwich structure. At this time, it should be noted that the lamination heights of the cast film strips should be the same, and the lamination thickness of each component should not be less than 1.4 mm, thus completing the composition gradient design.

[0104] (4) The above laminated cast film tape is subjected to hot isostatic pressing. The hot isostatic pressing temperature is 75 °C and the hot isostatic pressing pressure is 70 MPa. Then it is sintered at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0105] Example 9

[0106] The difference from Example 8 is as follows:

[0107] This example provides an alumina ceramic material, as Figure 6 shown, which includes two single alumina material layers 2 and three composite alumina material layers 1 (the first composite alumina material layer 11, the second composite alumina material layer 12, and the third composite alumina material layer 13, and the first composite alumina material layer 11, the second composite alumina material layer 12, and the third composite alumina material layer 13 have a gradient symmetric structure). The entire alumina ceramic material has a gradient symmetric structure. Specifically, in the first composite alumina material layer 11, the weight percentage of modified flaky alumina in the total weight of the first composite alumina material layer 11 is 5%, and the weight percentage of granular alumina in the total weight of the first composite alumina material layer 11 is 95%. In the second composite alumina material layer 12, the weight percentage of modified flaky alumina in the total weight of the second composite alumina material layer 12 is 10%, and the weight percentage of granular alumina in the total weight of the second composite alumina material layer 12 is 90%. In the third composite alumina material layer 13, the weight percentage of modified flaky alumina in the total weight of the third composite alumina material layer 13 is 5%, and the weight percentage of granular alumina in the total weight of the third composite alumina material layer 13 is 95%.

[0108] The preparation method of the alumina ceramic material in this example includes the following steps:

[0109] (1) The modified flaky alumina and granular alumina are respectively mixed according to the weight ratios of 0:100, 5:95, 10:90, 5:95, and 0:100. Alcohol is added as a ball milling medium. After ball milling for 10 h, they are dried at 150 °C to obtain mixed powders respectively.

[0110] (2) The above mixed powders are respectively placed in a three-dimensional mixer and mixed evenly, then alcohol and a binder (PVB) are added. The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film tape.

[0111] (3) After laminating the casting film tapes with 0 wt% of modified flaky alumina, continue to laminate the casting film tapes with 5 wt% of modified flaky alumina on this basis, then continue to laminate the casting film tapes with 10 wt% of modified flaky alumina, then continue to laminate the casting film tapes with 5 wt% of modified flaky alumina, and finally continue to laminate the casting film tapes with 0 wt% of modified flaky alumina to form a sandwich gradient symmetric structure. At this time, it should be noted that the lamination height of each casting film tape should be the same, and the laminated thickness of each component should not be less than 0.84 mm, thus completing the composition gradient design.

[0112] (4) The laminated casting film tapes are subjected to hot isostatic pressing. The hot isostatic pressing temperature is 75 °C and the hot isostatic pressing pressure is 70 MPa. Then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0113] Example 10

[0114] The difference from Example 8 is as follows:

[0115] This example provides an alumina ceramic material, such as Figure 7As shown in the figure, it includes two layers of single alumina material layer 2 and five layers of composite alumina material layer 1 (the first composite alumina material layer 11, the second composite alumina material layer 12, the third composite alumina material layer 13, the fourth composite alumina material layer 14, and the fifth composite alumina material layer 15. The first composite alumina material layer 11, the second composite alumina material layer 12, the third composite alumina material layer 13, the fourth composite alumina material layer 14, and the fifth composite alumina material layer 15 present a gradient symmetric structure), and the whole alumina ceramic material presents a gradient symmetric structure. Specifically, in the first composite alumina material layer 11, the weight percentage of modified flaky alumina in the total weight of the first composite alumina material layer 11 is 5%, and the weight percentage of granular alumina in the total weight of the first composite alumina material layer 11 is 95%. In the second composite alumina material layer 12, the weight percentage of modified flaky alumina in the total weight of the second composite alumina material layer 12 is 10%, and the weight percentage of granular alumina in the total weight of the second composite alumina material layer 12 is 90%. In the third composite alumina material layer 13, the weight percentage of modified flaky alumina in the total weight of the third composite alumina material layer 13 is 15%, and the weight percentage of granular alumina in the total weight of the third composite alumina material layer 13 is 85%. In the fourth composite alumina material layer 14, the weight percentage of modified flaky alumina in the total weight of the fourth composite alumina material layer 14 is 10%, and the weight percentage of granular alumina in the total weight of the fourth composite alumina material layer 14 is 90%. In the fifth composite alumina material layer 15, the weight percentage of modified flaky alumina in the total weight of the fifth composite alumina material layer 15 is 5%, and the weight percentage of granular alumina in the total weight of the fifth composite alumina material layer 15 is 95%.

[0116] The preparation method of the alumina ceramic material of this embodiment includes the following steps:

[0117] (1) Mix the modified flaky alumina and granular alumina according to the weight ratios of 0:100, 5:95, 10:90, 15:85, 10:90, 5:95, 0:100 respectively, add alcohol as the ball milling medium, and after ball milling for 10 h, dry at 150 °C to obtain mixed powders respectively.

[0118] (2) Place the above mixed powders in a three-dimensional mixer and mix them evenly, then add alcohol and a binder (PVB). The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film tape.

[0119] (3) After laminating the cast film tapes with 0 wt% of modified flaky alumina, continue to laminate the cast film tapes with 5 wt% of modified flaky alumina on this basis, then continue to laminate the cast film tapes with 10 wt% of modified flaky alumina, then continue to laminate the cast film tapes with 15 wt% of modified flaky alumina, then continue to laminate the cast film tapes with 10 wt% of modified flaky alumina, then continue to laminate the cast film tapes with 5 wt% of modified flaky alumina, and finally continue to laminate the cast film tapes with 0 wt% of modified flaky alumina to form a sandwich-type gradient symmetric structure. At this time, it should be noted that the lamination height of each cast film tape should be the same, and the laminated thickness of each component should not be less than 0.6 mm, thus completing the composition gradient design.

[0120] (4) The above laminated cast film tapes are subjected to hot isostatic pressing. The hot isostatic pressing temperature is 75 °C and the hot isostatic pressing pressure is 70 MPa, and then sintered at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0121] Example 11

[0122] The difference from Example 8 is that:

[0123] This example provides an alumina ceramic material, such as Figure 8As shown in the figure, it includes two layers of single alumina material layer 2 and seven layers of composite alumina material layer 1 (the first composite alumina material layer 11, the second composite alumina material layer 12, the third composite alumina material layer 13, the fourth composite alumina material layer 14, the fifth composite alumina material layer 15, the sixth composite alumina material layer 16, and the seventh composite alumina material layer 17. The first composite alumina material layer 11, the second composite alumina material layer 12, the third composite alumina material layer 13, the fourth composite alumina material layer 14, the fifth composite alumina material layer 15, the sixth composite alumina material layer 16, and the seventh composite alumina material layer 17 are in a gradient symmetric structure), and the whole alumina ceramic material is in a gradient symmetric structure. Specifically, in the first composite alumina material layer 11, the weight percentage of modified flaky alumina in the total weight of the first composite alumina material layer 11 is 5%, and the weight percentage of granular alumina in the total weight of the first composite alumina material layer 11 is 95%. In the second composite alumina material layer 12, the weight percentage of modified flaky alumina in the total weight of the second composite alumina material layer 12 is 10%, and the weight percentage of granular alumina in the total weight of the second composite alumina material layer 12 is 90%. In the third composite alumina material layer 13, the weight percentage of modified flaky alumina in the total weight of the third composite alumina material layer 13 is 15%, and the weight percentage of granular alumina in the total weight of the third composite alumina material layer 13 is 85%. In the fourth composite alumina material layer 14, the weight percentage of modified flaky alumina in the total weight of the fourth composite alumina material layer 14 is 20%, and the weight percentage of granular alumina in the total weight of the fourth composite alumina material layer 14 is 80%. In the fifth composite alumina material layer 15, the weight percentage of modified flaky alumina in the total weight of the fifth composite alumina material layer 15 is 15%, and the weight percentage of granular alumina in the total weight of the fifth composite alumina material layer 15 is 85%. In the sixth composite alumina material layer 16, the weight percentage of modified flaky alumina in the total weight of the sixth composite alumina material layer 16 is 10%, and the weight percentage of granular alumina in the total weight of the sixth composite alumina material layer 16 is 90%. In the seventh composite alumina material layer 17, the weight percentage of modified flaky alumina in the total weight of the seventh composite alumina material layer 17 is 5%, and the weight percentage of granular alumina in the total weight of the seventh composite alumina material layer 17 is 95%. As Figure 9 shown, it is a partial cross-sectional microscopic schematic diagram of the composite alumina material layer 1. From Figure 9 it can be seen that the pores are mainly concentrated in the area where the content of modified flaky alumina is 20%. In the area where the content of modified flaky alumina is less, the corresponding pores are also less.

[0124] The preparation method of the alumina ceramic material of this embodiment includes the following steps:

[0125] (1) Mix the modified flaky alumina and granular alumina according to the weight ratios of 0:100, 5:95, 10:90, 15:85, 20:80, 15:85, 10:90, 5:95, and 0:100 respectively. Add alcohol as the ball-milling medium, and after ball-milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0126] (2) Place the above-mentioned mixed powders in a three-dimensional mixer and mix them evenly. Then add alcohol and a binder (PVB). Place the obtained slurry in a casting machine and cast at 60 °C to obtain a cast film tape.

[0127] (3) Stack the cast film tapes with 0 wt% of modified flaky alumina content. On this basis, continue to stack the cast film tapes with 5 wt% of modified flaky alumina content, continue to stack the cast film tapes with 10 wt% of modified flaky alumina content, continue to stack the cast film tapes with 15 wt% of modified flaky alumina content, continue to stack the cast film tapes with 20 wt% of modified flaky alumina content, continue to stack the cast film tapes with 15 wt% of modified flaky alumina content, continue to stack the cast film tapes with 10 wt% of modified flaky alumina content, continue to stack the cast film tapes with 5 wt% of modified flaky alumina content, and continue to stack the cast film tapes with 0 wt% of modified flaky alumina content to form a sandwich-type gradient symmetric structure. At this time, it should be noted that the stacking heights of the cast film tapes should be the same, and the laminated thickness of each component should not be less than 0.47 mm, thus completing the composition gradient design.

[0128] (4) Perform hot isostatic pressing on the above-mentioned stacked cast film tapes. The hot isostatic pressing temperature is 75 °C, and the hot isostatic pressing pressure is 70 MPa. Then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina ceramic material.

[0129] Example 12

[0130] The difference from Example 9 is as follows:

[0131] In the first composite alumina material layer 11, the weight percentage of the modified flaky alumina in the total weight of the first composite alumina material layer 11 is 10%, and the weight percentage of the granular alumina in the total weight of the first composite alumina material layer 11 is 90%. In the second composite alumina material layer 12, the weight percentage of the modified flaky alumina in the total weight of the second composite alumina material layer 12 is 20%, and the weight percentage of the granular alumina in the total weight of the second composite alumina material layer 12 is 80%. In the third composite alumina material layer 13, the weight percentage of the modified flaky alumina in the total weight of the third composite alumina material layer 13 is 10%, and the weight percentage of the granular alumina in the total weight of the third composite alumina material layer 13 is 90%.

[0132] The preparation method of the alumina ceramic material in this embodiment includes the following steps:

[0133] (1) Mix the modified flaky alumina and granular alumina according to the weight ratios of 0:100, 10:90, 20:80, 10:90, and 0:100 respectively. Add alcohol as the ball-milling medium, and after ball-milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0134] (2) Place the above-mentioned mixed powders in a three-dimensional mixer and mix them evenly, then add alcohol and a binder (PVB). The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film tape.

[0135] (3) Stack the cast film tapes with 0 wt% of modified flaky alumina content, and then continue to stack the cast film tapes with 10 wt% of modified flaky alumina content, continue to stack the cast film tapes with 20 wt% of modified flaky alumina content, continue to stack the cast film tapes with 10 wt% of modified flaky alumina content, and continue to stack the cast film tapes with 0 wt% of modified flaky alumina content to form a sandwich gradient symmetric structure. At this time, it should be noted that the stacking heights of the cast film tapes should be the same, and the laminated thickness of each component should not be less than 0.84 mm, thus completing the composition gradient design.

[0136] (4) Perform hot isostatic pressing on the stacked cast film tapes. The hot isostatic pressing temperature is 75 °C, and the hot isostatic pressing pressure is 70 MPa. Then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0137] Example 13

[0138] The difference from Example 1 is that:

[0139] This embodiment provides an alumina ceramic material, as Figure 10 shown, which is composed of three layers of composite alumina material layers 1. The three layers of composite alumina material layers 1 include a first composite alumina material layer 11, a second composite alumina material layer 12, and a third composite alumina material layer 13, showing a gradient symmetric structure. Specifically, in the first composite alumina material layer 11, the weight percentage of the modified flaky alumina in the total weight of the first composite alumina material layer 11 is 5%, and the weight percentage of the granular alumina in the total weight of the first composite alumina material layer 11 is 95%. In the second composite alumina material layer 12, the weight percentage of the modified flaky alumina in the total weight of the second composite alumina material layer 12 is 10%, and the weight percentage of the granular alumina in the total weight of the second composite alumina material layer 12 is 90%. In the third composite alumina material layer 13, the weight percentage of the modified flaky alumina in the total weight of the third composite alumina material layer 13 is 5%, and the weight percentage of the granular alumina in the total weight of the third composite alumina material layer 13 is 95%.

[0140] The preparation method of the alumina ceramic material of this embodiment includes the following steps:

[0141] (1) Mix the modified flaky alumina and granular alumina according to the weight ratios of 5:95, 10:90, and 5:95 respectively, add alcohol as the ball-milling medium, and after ball-milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0142] (2) Place the above-mentioned mixed powders in a three-dimensional mixer to mix evenly, then add alcohol and a binder (PVB). The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film tape.

[0143] (3) After laminating the cast film tapes with a modified flaky alumina content of 5 wt%, continue to laminate the cast film tapes with a modified flaky alumina content of 10 wt% on this basis, and then continue to laminate the cast film tapes with a modified flaky alumina content of 5 wt% to form a sandwich structure. At this time, it should be noted that the lamination heights of the cast film tapes should be the same, and the laminated thickness of each component should not be less than 1.4 mm, thus completing the composition gradient design.

[0144] (4) The laminated cast film tapes are subjected to hot isostatic pressing. The hot isostatic pressing temperature is 75 °C and the hot isostatic pressing pressure is 70 MPa, and then sintered at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0145] Example 14

[0146] The difference from Example 13 is as follows:

[0147] In the first composite alumina material layer 11, the weight percentage of the modified flaky alumina in the total weight of the first composite alumina material layer 11 is 10%, and the weight percentage of the granular alumina in the total weight of the first composite alumina material layer 11 is 90%. In the second composite alumina material layer 12, the weight percentage of the modified flaky alumina in the total weight of the second composite alumina material layer 12 is 15%, and the weight percentage of the granular alumina in the total weight of the second composite alumina material layer 12 is 85%. In the third composite alumina material layer 13, the weight percentage of the modified flaky alumina in the total weight of the third composite alumina material layer 13 is 10%, and the weight percentage of the granular alumina in the total weight of the third composite alumina material layer 13 is 90%.

[0148] The preparation method of the alumina ceramic material of this embodiment includes the following steps:

[0149] (1) Mix the modified flaky alumina and granular alumina according to the weight ratios of 10:90, 15:85, and 10:90 respectively, add alcohol as the ball-milling medium, and after ball-milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0150] (2) The above-mentioned mixed powder is respectively placed in a three-dimensional mixer and mixed evenly, then alcohol and binder (PVB) are added. The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film tape.

[0151] (3) After laminating the cast film tapes with 10 wt% of modified flaky alumina, on this basis, continue to laminate the cast film tapes with 15 wt% of modified flaky alumina, and then continue to laminate the cast film tapes with 10 wt% of modified flaky alumina to form a sandwich structure. At this time, it should be noted that the lamination height of each cast film tape should be the same, and the laminated thickness of each component is not less than 1.4 mm, thus completing the composition gradient design.

[0152] (4) The above-mentioned laminated cast film tapes are subjected to hot isostatic pressing. The hot isostatic pressing temperature is 75 °C and the hot isostatic pressing pressure is 70 MPa, and then sintered at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0153] Example 15

[0154] The difference from Example 14 is as follows:

[0155] This example provides an alumina ceramic material, as Figure 11 shown, which is composed of five layers of composite alumina material layers 1. The five layers of composite alumina material layers 1 include a first composite alumina material layer 11, a second composite alumina material layer 12, a third composite alumina material layer 13, a fourth composite alumina material layer 14, and a fifth composite alumina material layer 15, showing a gradient symmetric structure. Specifically, in the first composite alumina material layer 11, the weight percentage of modified flaky alumina in the total weight of the first composite alumina material layer 11 is 5%, and the weight percentage of granular alumina in the total weight of the first composite alumina material layer 11 is 95%. In the second composite alumina material layer 12, the weight percentage of modified flaky alumina in the total weight of the second composite alumina material layer 12 is 10%, and the weight percentage of granular alumina in the total weight of the second composite alumina material layer 12 is 90%. In the third composite alumina material layer 13, the weight percentage of modified flaky alumina in the total weight of the third composite alumina material layer 13 is 15%, and the weight percentage of granular alumina in the total weight of the third composite alumina material layer 13 is 85%. In the fourth composite alumina material layer 14, the weight percentage of modified flaky alumina in the total weight of the fourth composite alumina material layer 14 is 10%, and the weight percentage of granular alumina in the total weight of the fourth composite alumina material layer 14 is 90%. In the fifth composite alumina material layer 15, the weight percentage of modified flaky alumina in the total weight of the fifth composite alumina material layer 15 is 5%, and the weight percentage of granular alumina in the total weight of the fifth composite alumina material layer 15 is 95%.

[0156] The preparation method of the alumina ceramic material of this embodiment includes the following steps:

[0157] (1) Mix the modified flaky alumina and granular alumina respectively according to the weight ratios of 5:95, 10:90, 15:85, 10:90, and 5:95. Add alcohol as the ball milling medium. After ball milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0158] (2) Place the above-mentioned mixed powders in a three-dimensional mixer respectively. After mixing evenly, add alcohol and a binder (PVB). Place the obtained slurry in a casting machine and cast at 60 °C to obtain a cast film tape.

[0159] (3) Stack the cast film tapes with a modified flaky alumina content of 5 wt%. On this basis, continue to stack the cast film tapes with a modified flaky alumina content of 10 wt%, continue to stack the cast film tapes with a modified flaky alumina content of 15 wt%, continue to stack the cast film tapes with a modified flaky alumina content of 10 wt%, and continue to stack the cast film tapes with a modified flaky alumina content of 5 wt% to form a sandwich structure. At this time, it should be noted that the stacking heights of the cast film tapes should be the same, and the laminated thickness of each component should not be less than 0.84 mm, thereby completing the composition gradient design.

[0160] (4) Perform hot isostatic pressing on the stacked cast film tapes. The hot isostatic pressing temperature is 75 °C, and the hot isostatic pressing pressure is 70 MPa. Then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0161] Example 16

[0162] The difference from Example 15 is:

[0163] In the first composite alumina material layer 11, the weight percentage of the modified flaky alumina in the total weight of the first composite alumina material layer 11 is 10%, and the weight percentage of the granular alumina in the total weight of the first composite alumina material layer 11 is 90%. In the second composite alumina material layer 12, the weight percentage of the modified flaky alumina in the total weight of the second composite alumina material layer 12 is 15%, and the weight percentage of the granular alumina in the total weight of the second composite alumina material layer 12 is 85%. In the third composite alumina material layer 13, the weight percentage of the modified flaky alumina in the total weight of the third composite alumina material layer 13 is 20%, and the weight percentage of the granular alumina in the total weight of the third composite alumina material layer 13 is 80%. In the fourth composite alumina material layer 14, the weight percentage of the modified flaky alumina in the total weight of the fourth composite alumina material layer 14 is 15%, and the weight percentage of the granular alumina in the total weight of the fourth composite alumina material layer 14 is 85%. In the fifth composite alumina material layer 15, the weight percentage of the modified flaky alumina in the total weight of the fifth composite alumina material layer 15 is 10%, and the weight percentage of the granular alumina in the total weight of the fifth composite alumina material layer 15 is 90%.

[0164] The preparation method of the alumina ceramic material in this embodiment includes the following steps:

[0165] (1) Mix the modified flaky alumina and the granular alumina according to the weight ratios of 10:90, 15:85, 20:80, 15:85, and 10:90 respectively. Add alcohol as the ball milling medium, and after ball milling for 10 h, dry at 150 °C to obtain the mixed powders respectively.

[0166] (2) Place the above-mentioned mixed powders in a three-dimensional mixer and mix them evenly, then add alcohol and a binder (PVB). The obtained slurry is placed in a casting machine and cast at 60 °C to obtain a cast film tape.

[0167] (3) Stack the cast film tapes with a modified flaky alumina content of 10 wt%. On this basis, continue to stack the cast film tapes with a modified flaky alumina content of 15 wt%, continue to stack the cast film tapes with a modified flaky alumina content of 20 wt%, continue to stack the cast film tapes with a modified flaky alumina content of 15 wt%, and continue to stack the cast film tapes with a modified flaky alumina content of 10 wt% to form a sandwich structure. At this time, it should be noted that the stacking heights of the cast film tapes should be the same, and the stacking thicknesses of each component should not be less than 0.84 mm, thus completing the composition gradient design.

[0168] (4) Perform hot isostatic pressing on the above-mentioned stacked cast film tapes. The hot isostatic pressing temperature is 75 °C, the hot isostatic pressing pressure is 70 MPa, and then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0169] Example 17

[0170] The difference from Example 16 is as follows:

[0171] This example provides an alumina ceramic material, as Figure 12 shown, which is composed of seven layers of composite alumina material layers 1. The seven layers of composite alumina material layers 1 include a first composite alumina material layer 11, a second composite alumina material layer 12, a third composite alumina material layer 13, a fourth composite alumina material layer 14, a fifth composite alumina material layer 15, a sixth composite alumina material layer 16, and a seventh composite alumina material layer 17. The first composite alumina material layer 11, the second composite alumina material layer 12, the third composite alumina material layer 13, the fourth composite alumina material layer 14, the fifth composite alumina material layer 15, the sixth composite alumina material layer 16, and the seventh composite alumina material layer 17 have a gradient symmetric structure. Specifically, in the first composite alumina material layer 11, the weight percentage of modified flaky alumina in the total weight of the first composite alumina material layer 11 is 5%, and the weight percentage of granular alumina in the total weight of the first composite alumina material layer 11 is 95%. In the second composite alumina material layer 12, the weight percentage of modified flaky alumina in the total weight of the second composite alumina material layer 12 is 10%, and the weight percentage of granular alumina in the total weight of the second composite alumina material layer 12 is 90%. In the third composite alumina material layer 13, the weight percentage of modified flaky alumina in the total weight of the third composite alumina material layer 13 is 15%, and the weight percentage of granular alumina in the total weight of the third composite alumina material layer 13 is 85%. In the fourth composite alumina material layer 14, the weight percentage of modified flaky alumina in the total weight of the fourth composite alumina material layer 14 is 20%, and the weight percentage of granular alumina in the total weight of the fourth composite alumina material layer 14 is 80%. In the fifth composite alumina material layer 15, the weight percentage of modified flaky alumina in the total weight of the fifth composite alumina material layer 15 is 15%, and the weight percentage of granular alumina in the total weight of the fifth composite alumina material layer 15 is 85%. In the sixth composite alumina material layer 16, the weight percentage of modified flaky alumina in the total weight of the sixth composite alumina material layer 16 is 10%, and the weight percentage of granular alumina in the total weight of the sixth composite alumina material layer 16 is 90%. In the seventh composite alumina material layer 17, the weight percentage of modified flaky alumina in the total weight of the seventh composite alumina material layer 17 is 5%, and the weight percentage of granular alumina in the total weight of the seventh composite alumina material layer 17 is 95%.

[0172] The preparation method of the alumina ceramic material in this example includes the following steps:

[0173] (1) Mix the modified flaky alumina and granular alumina according to the weight ratios of 5:95, 10:90, 15:85, 20:80, 15:85, 10:90, and 5:95 respectively. Add alcohol as the ball-milling medium and ball-mill for 10 h, then dry at 150 °C to obtain the mixed powders respectively.

[0174] (2) Place the above-mentioned mixed powders in a three-dimensional mixer and mix them evenly, then add alcohol and binder (PVB). Place the obtained slurry in a casting machine and cast at 60 °C to obtain a cast film strip.

[0175] (3) Stack the cast film strips with 5 wt% of modified flaky alumina content. On this basis, continue to stack the cast film strips with 10 wt% of modified flaky alumina content, then continue to stack the cast film strips with 15 wt% of modified flaky alumina content, then continue to stack the cast film strips with 20 wt% of modified flaky alumina content, then continue to stack the cast film strips with 15 wt% of modified flaky alumina content, then continue to stack the cast film strips with 10 wt% of modified flaky alumina content, and finally continue to stack the cast film strips with 5 wt% of modified flaky alumina content to form a sandwich structure. At this time, it should be noted that the stacking heights of the cast film strips should be the same, and the stacking thickness of each component should not be less than 0.6 mm, thus completing the composition gradient design.

[0176] (4) Perform hot isostatic pressing on the above-mentioned stacked cast film strips. The hot isostatic pressing temperature is 75 °C, and the hot isostatic pressing pressure is 70 MPa. Then sinter at 1600 °C for 2 h to finally obtain a high-strength alumina material.

[0177] Comparative Example 1

[0178] This comparative example provides an alumina ceramic material, which is different from Example 1 in that it consists of a single layer of alumina material layer, and its preparation method includes the following steps:

[0179] (1) Place the high-purity granular alumina raw material in a three-dimensional mixer and mix it evenly, then add alcohol, binder and other auxiliary materials to form a ceramic slurry. Then place the slurry in a casting machine and cast within the range of 60 °C to obtain a cast film strip.

[0180] (2) Perform stacked hot isostatic pressing on the above-mentioned cast film strip. The hot isostatic pressing temperature is 75 °C, and the hot isostatic pressing pressure is 70 MPa. Then sinter at 1625 °C for 2 h to finally obtain a high-strength alumina ceramic material.

[0181] Comparative Example 2

[0182] The difference from Example 1 is as follows:

[0183] This comparative example provides an alumina ceramic material. In the composite alumina material layer, the modified flaky alumina accounts for 20% of the total weight of the alumina ceramic material, and the granular alumina accounts for 80% of the total weight of the alumina ceramic material.

[0184] Step (1) of the preparation method of the alumina ceramic material in this example is to mix the modified flaky alumina and the granular alumina according to a weight ratio of 20:80, add alcohol as the ball milling medium, ball mill for 10 h, and then dry at 150 °C to obtain a mixed powder.

[0185] Table 1 List of raw material compositions and experimental parameters of the alumina ceramic materials in the examples and comparative examples

[0186]

[0187]

[0188] The alumina ceramic materials in the examples and comparative examples were subjected to performance tests. The test methods are as follows, and the test results are shown in Table 2 below:

[0189] Test method for dielectric constant: Resonant cavity method.

[0190] Test method for dielectric loss: Resonant cavity method.

[0191] Test method for flexural strength: Three-point bending strength test method.

[0192] Table 2 Performance list of the alumina ceramic materials in the examples and comparative examples

[0193]

[0194]

[0195] Figure 13 With Figure 14 is the Weibull distribution diagram of the samples. 10 samples were tested for each group of examples of the present invention. After calculation, the slope (β) of the samples in each group of examples is greater than 8, indicating that the data reliability of the samples is relatively high. In the Weibull distribution, the abscissa corresponding to the intersection of the fitting line of each group of samples and the x-axis (y = 0) is the logarithm of the sample average bending strength with e as the base. From Figure 13 and Figure 14 it can be seen that the bending strength of the samples increases after adding flaky alumina, and the bending strength first increases and then decreases with the increase of the content of flaky alumina.

[0196] Combined with Table 1, Table 2, Figure 13 and Figure 14It can be seen that the alumina ceramic material of the present invention has adjustable dielectric constant, low dielectric loss and high flexural strength. The flexural strength at room temperature is as high as 570 MPa, the dielectric constant can be 10-11, and the dielectric loss is lower than 3×10 -4 . As the content of the modified flaky alumina increases, the dielectric constant of the alumina ceramic material decreases, and at the same time, the dielectric loss increases slowly. The flexural strength first increases and then decreases with the increase of the overall content of the modified flaky alumina, indicating that the modified flaky alumina has a promoting effect on the flexural strength of the alumina matrix. In addition, through the design of the composition gradient structure, it is found that as the number of layers increases, the dielectric loss of the alumina ceramic material increases, while the flexural strength first increases and then decreases, indicating that the composition gradient structure has a promoting effect on the flexural strength of the alumina matrix. In summary, when the content of the flaky alumina ceramic powder increases to 8.88 wt%, the dielectric constant of the alumina ceramic material decreases, and due to the decrease of the alumina content, the dielectric loss increases, and the flexural strength also increases. When the content of the modified flaky alumina continues to increase, the dielectric constant continues to decrease, the dielectric loss increases, and the flexural strength continues to decrease. Since the dielectric constant of the modified flaky alumina is lower than the dielectric constant of the system, the overall dielectric constant decreases. When there is too much modified flaky alumina, due to too many phase interfaces, the dielectric loss increases. However, the arrangement of the modified flaky alumina also increases the flexural strength of the system. Through the surface modification of polysilazane, the dielectric constant of the alumina ceramic material decreases, but the dielectric loss increases slightly, and the flexural strength also increases significantly. When the content of the modified flaky alumina in the system is 8 wt%-9 wt%, and the alumina ceramic material has a sandwich structure with a composition gradient, the dielectric properties and flexural strength are the best. Therefore, Example 11 obtains the best comprehensive performance.

[0197] 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 described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and 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. An alumina ceramic material, characterized in that, It includes a composite alumina material layer, and the composite alumina material layer includes modified flaky or rod-shaped alumina and granular alumina. The modified flaky or rod-shaped alumina accounts for 1%-15% of the total weight of the alumina ceramic material, and the granular alumina accounts for 85%-99% of the total weight of the alumina ceramic material.

2. The alumina ceramic material according to claim 1, characterized in that, The modified flaky or rod-shaped alumina is obtained by modifying flaky or rod-shaped alumina with a coupling agent. Preferably, the coupling agent is polysilazane; and / or, the dosage of the coupling agent is 1%-1.5% of the flaky or rod-shaped alumina.

3. The alumina ceramic material according to claim 1 or 2, characterized in that, The radial dimension of the modified flaky or rod-shaped alumina is 5 μm - 50 μm, and the thickness is 0.1 μm - 2 μm. The D 50 particle size of the granular alumina is below 1 μm; and / or, D of the alumina ceramic material 50 has a particle size of 200 nm - 1.5 μm, preferably 200 nm - 1 μm.

4. The alumina ceramic material according to any one of claims 1 - 3, characterized in that, It further includes a single alumina material layer, and the single alumina material layer is composed of granular alumina; the composite alumina material layer is disposed on one side surface of the single alumina material layer or between two single alumina material layers.

5. The alumina ceramic material according to claim 4, characterized in that, The alumina ceramic material includes one single alumina material layer and multiple composite alumina material layers. The multiple composite alumina material layers are sequentially stacked on one side surface of the single alumina material layer, and along the direction away from the single alumina material layer, in the multiple composite alumina material layers, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer increases sequentially, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer decreases sequentially.

6. The alumina ceramic material according to claim 4, characterized in that, The alumina ceramic material includes two single alumina material layers and multiple composite alumina material layers. The multiple composite alumina material layers are disposed between the two single alumina material layers, and along the direction from one single alumina material layer to the other single alumina material layer, in the multiple composite alumina material layers, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer first increases sequentially and then decreases sequentially, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer first decreases sequentially and then increases sequentially. Preferably, the multiple composite alumina material layers have a gradient symmetric structure; along the direction from one single alumina material layer to the other single alumina material layer, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer first increases equally sequentially and then decreases equally sequentially, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer first decreases equally sequentially and then increases equally sequentially.

7. The alumina ceramic material according to claim 6, characterized in that, The alumina ceramic material includes two single alumina material layers and seven composite alumina material layers. Along the direction from one single alumina material layer to the other single alumina material layer, in the multiple composite alumina material layers, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer is 5%, 10%, 15%, 20%, 15%, 10%, 5% in sequence, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer is 95%, 90%, 85%, 80%, 85%, 90%, 95% in sequence.

8. The alumina ceramic material according to claim 1, characterized in that, It is formed by laminating multiple layers of composite alumina materials; along the thickness direction of the alumina ceramic material, from one end of the alumina ceramic material to the other end, in the multi-layer composite alumina material layer, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer first increases successively and then decreases successively, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer first decreases successively and then increases successively; Preferably, the multi-layer composite alumina material layer has a gradient symmetric structure; along the thickness direction of the alumina ceramic material, from one end of the alumina ceramic material to the other end, in the multi-layer composite alumina material layer, the weight percentage of the modified flaky or rod-shaped alumina in the total weight of the composite alumina material layer first increases equally successively and then decreases equally successively, and the weight percentage of the granular alumina in the total weight of the composite alumina material layer first decreases equally successively and then increases equally successively.

9. A preparation method of the alumina ceramic material according to any one of claims 1 - 8, characterized in that, It includes the following steps: After uniformly mixing the modified flaky or rod-shaped alumina and the granular alumina, mix them uniformly with a solvent and a binder to obtain a slurry; cast the obtained slurry to obtain a cast film strip; Perform hot isostatic pressing on the obtained cast film strip and then sinter it to obtain an alumina ceramic material.

10. The preparation method according to claim 9, characterized in that, The solvent is selected from at least one of water, toluene, and alcohol; And / or, the binder is selected from at least one of PVB, ethyl cellulose, and PVA; the dosage of the binder is 5%-15% of the sum of the weights of the modified flaky or rod-shaped alumina and the granular alumina; And / or, the temperature used during the casting process is 50°C - 70°C, and the blade thickness is 100μm - 600μm; And / or, the temperature used during the hot isostatic pressing process is 50°C - 85°C, and the pressure is 30MPa - 70MPa; And / or, the sintering temperature is 1500°C - 1650°C, and the time is 1h - 4h.

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