A kind of high thermal shock alumina composite ceramic and preparation method thereof

Abstract

The present invention relates to the field of ceramic technology, and specifically to a high thermal shock alumina composite ceramic and a preparation method thereof, comprising the following raw materials in parts by weight: 65-95 parts of an Al2O3-ZrO2 / ceramic fiber or whisker composition, 100-200 parts of deionized water, 8-12 parts of a plasticizer, and 2-15 parts of a low thermal expansion coefficient base material. The present invention reduces the thermal expansion coefficient of the alumina ceramic by adding ZrO2 / ceramic fiber or whisker to alumina, introducing ceramic fiber or whisker binary toughening while introducing ZrO2 phase change toughening, and introducing a unit with a lower thermal expansion coefficient or a negative thermal expansion coefficient. High-energy ball milling improves the uniformity of the powder interface, thereby improving the thermal shock resistance of the alumina composite ceramic. The method for preparing the ceramic is simple to operate, has high production efficiency, and low production cost. The ceramic round tube made of the alumina composite ceramic can meet the high thermal shock resistance requirements and can be widely used in environments with sudden temperature changes.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramics, and in particular to a high thermal shock alumina composite ceramic and a preparation method thereof. Background Art

[0002] The ability of a material to resist damage under conditions of rapid temperature changes. This is called thermal stability, thermal shock stability, thermal shock resistance, resistance to rapid temperature changes, and resistance to rapid cooling and heating.

[0003] Alumina ceramics is a ceramic material with aluminum oxide as the main body. It has good conductivity, mechanical strength and high temperature resistance. It is the basic material for manufacturing high-performance ceramic components such as high strength, wear resistance and high temperature resistance. Therefore, alumina ceramics have been widely used in high-strength structural ceramics, alumina ceramic substrates and heating elements in pressure sensors, bathroom, smart toilets and other fields.

[0004] However, existing alumina ceramic materials are very brittle and cannot withstand huge mechanical and thermal shocks, that is, their thermal shock resistance is poor. When used in high-temperature environments, their thermal shock resistance is poor, which reduces their service life. Therefore, it is necessary to improve and enhance their thermal shock resistance. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a high thermal shock resistance alumina composite ceramic, by adding ZrO2 / ceramic fibers or whiskers to alumina, introducing ZrO2 phase change toughening and ceramic fibers or whiskers binary toughening at the same time, and introducing units with a lower thermal expansion coefficient or a negative thermal expansion coefficient to reduce the thermal expansion coefficient of the alumina ceramic, and using high-energy ball milling to improve the consistency of the powder interface, thereby improving the thermal shock resistance of the alumina composite ceramic.

[0006] Another object of the present invention is to provide a method for preparing high thermal shock alumina composite ceramics. The process is simple to operate, easy to control, has high production efficiency, and low production cost. The density of the ceramic round tube produced is ≥98%, the bending strength is ≥250MPa, and the thermal shock resistance is ≥230℃; therefore, the ceramic round tube made of alumina composite ceramics can meet the high thermal shock resistance requirements and can be widely used in environments with sudden temperature changes.

[0007] The purpose of the present invention is achieved through the following technical solution: a high thermal shock alumina composite ceramic, comprising the following raw materials in parts by weight: 65-95 parts of an Al2O3-ZrO2 / ceramic fiber or whisker composition, 100-200 parts of deionized water, 8-12 parts of a plasticizer, and 2-15 parts of a low thermal expansion coefficient base material.

[0008] Preferably, the composite ceramic comprises the following raw materials in parts by weight: 65-95 parts of Al2O3-ZrO2 / ceramic fiber or whisker composition, 100-200 parts of deionized water, 8-12 parts of plasticizer, and 5-15 parts of low thermal expansion coefficient base material.

[0009] In the present invention, ZrO2 / ceramic fibers or whiskers are added to alumina, and ZrO2 phase change toughening is introduced while ceramic fibers or whiskers are introduced for binary toughening, and Mg2Al4Si5O is introduced. 18 Cordierite, 3Al2O3·2SiO2 (mullite), MgO (magnesium oxide), Al2[SiO4]O (andalusite), and aluminum titanate have low or negative thermal expansion coefficients, reducing the thermal expansion coefficient of alumina ceramics. High-energy ball milling improves the uniformity of the powder interface and enhances the thermal shock resistance of alumina composite ceramics. The use of ZrO2 increases the toughness of alumina composite ceramics. The main toughening mechanisms of whisker-toughened ceramic-matrix composites include whisker pullout, crack deflection, and whisker bridging, similar to those of fiber-toughened ceramic-matrix composites. The whisker toughening effect does not vary with temperature. Fibers are fibrous, lightweight refractory materials with advantages such as light weight, high temperature resistance, good thermal stability, low thermal conductivity, low specific heat, and resistance to mechanical vibration. Adding them to alumina composite ceramics can further reduce the thermal expansion coefficient of alumina and improve the thermal conductivity and strength of the material.

[0010] Preferably, the ceramic fibers or whiskers include at least one of zirconium oxide fibers or whiskers, magnesium oxide fibers or whiskers, silicon carbide fibers or whiskers, and silicon nitride fibers or whiskers.

[0011] Preferably, the low thermal expansion coefficient base material comprises Mg2Al4Si5O 18 0.5-5 parts, 3Al2O3·2SiO20.5-5 parts, MgO 0.2-1 parts, Al2[SiO4]O 0.5-2 parts and aluminum titanate 0.5-2 parts; it has a low thermal expansion coefficient or a negative thermal expansion coefficient unit, which reduces the thermal expansion coefficient of alumina ceramics, improves the uniformity of the powder interface through high-energy ball milling, and improves the thermal shock resistance of alumina composite ceramics.

[0012] Preferably, the plasticizer is at least one of carboxymethyl cellulose with a mass concentration of 15-30% and PVA plasticizer with a mass concentration of 8-20%.

[0013] The function of the plasticizer used in the present invention is to improve the molding performance, help the powder to produce plastic deformation, not easy to crack during molding, improve the strength, be suitable for spray drying, and be beneficial to dry pressing or isostatic pressing to improve the density of the ceramic blank tube and the consistency of size.

[0014] Preferably, the Al2O3-ZrO2 / ceramic fiber or whisker composition is composed of Al2O3, ZrO2, ceramic fiber or whisker in a weight ratio of 1:0.05-0.3:0.005-0.05.

[0015] The present invention also provides a method for preparing a high thermal shock alumina composite ceramic, comprising the following steps:

[0016] S1. Mix Al2O3, ZrO2, and ceramic fibers or whiskers to obtain a primary mixed powder for later use;

[0017] S2. Add the low thermal expansion coefficient base material to the primary mixed powder obtained in step S1 and mix and stir evenly to obtain a secondary mixed powder for later use;

[0018] S3. Add the secondary mixed powder obtained in step S2 to deionized water, and then add the plasticizer and mix evenly to obtain a mixed slurry for later use;

[0019] S4, preparing granulated powder by centrifugal spray granulation of the mixed slurry obtained in step S3, and setting aside;

[0020] S5, forming a ceramic tube blank by dry pressing or isostatic pressing the granulated powder obtained in step S4, and setting aside;

[0021] S6. The ceramic tube blank obtained in step S5 is placed at a temperature of 1100-1300° C. and sintered independently for 1-3 hours using air sintering to obtain a sintered ceramic tube blank for later use.

[0022] S7, cutting and cylindrically grinding the ceramic blank tube obtained in step S6 to obtain a ceramic tube formed in one step; and setting aside;

[0023] S8. Place the ceramic round tube obtained in step S7 at a temperature of 1550-1650° C. and perform secondary sintering independently for 0.5-2 hours. The sintering method is air sintering to obtain an alumina composite ceramic round tube.

[0024] The alumina composite ceramic round tube in the present invention is prepared by the above method, and the alumina composite ceramic prepared by the above method has the advantages of high thermal shock resistance, low expansion coefficient, and high flexural strength. The ceramic round tube prepared under a specific sintering process has a density ≥98%, a bending strength ≥250MPa, and a thermal shock resistance ≥230°C; therefore, the ceramic round tube made of alumina composite ceramic meets the high thermal shock resistance requirements and can be widely used in temperature sudden change environments.

[0025] Preferably, high-energy ball milling is used for mixing in step S3, the rotation speed during ball milling is 200-300 r / min, and the ball milling mixing time is 18-24 h.

[0026] Preferably, during the centrifugal spray granulation in step S4, the inlet air temperature is 250-300°C, the outlet air temperature is 90-140°C, the centrifugal frequency is 90-130HZ, and the feeding speed is 15-55r / min.

[0027] Preferably, the particle size of the granulated powder in step S4 is concentrated between 80-300 meshes.

[0028] Preferably, the isostatic pressing pressure in step S5 is 100-200 MPa, the temperature is 60-80° C., and the holding time is 300-1500 s.

[0029] The beneficial effects of the present invention are as follows: by adding ZrO2 / ceramic fibers or whiskers into alumina, the present invention introduces ZrO2 phase change toughening and ceramic fibers or whiskers binary toughening at the same time, and introduces Mg2Al4Si5O 18 , 3Al2O3·2SiO2, MgO, Al2[SiO4]O, and aluminum titanate have lower thermal expansion coefficients or negative expansion coefficient units, which reduce the thermal expansion coefficient of alumina ceramics, and use high-energy ball milling to improve the uniformity of the powder interface and improve the thermal shock resistance of alumina composite ceramics.

[0030] The preparation method of the high thermal shock resistance alumina composite ceramic of the present invention is simple to operate, convenient to control, high in production efficiency and low in production cost. The density of the prepared ceramic round tube is ≥98%, the bending strength is ≥250MPa and the thermal shock resistance is ≥230°C. Therefore, the ceramic round tube made of the alumina composite ceramic can meet the high thermal shock resistance requirements and can be widely used in environments with sudden temperature changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is an SEM image of the zirconium oxide fiber added in Example 2;

[0032] Figure 2 This is an SEM image of Example 2 with the addition of low expansion coefficient (cordierite);

[0033] Figure 3 This is a SEM image comparing the particle size of the powder after high-energy ball milling in Example 3. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of those skilled in the art, the following embodiments and accompanying drawings are provided. Figure 1-3 The present invention is further described, and the contents mentioned in the embodiment are not intended to limit the present invention.

[0035] Example 1

[0036] A high thermal shock alumina composite ceramic comprises the following raw materials in parts by weight: 65 parts of an Al2O3-ZrO2 / whisker composition, 100 parts of deionized water, 8 parts of a plasticizer, and 2 parts of a low thermal expansion coefficient base material.

[0037] The low thermal expansion coefficient base material includes Mg2Al4Si5O 18 0.5 part, 3Al2O3·2SiO2 0.5 part, MgO 0.2 part, Al2[SiO4]O 0.5 part and aluminum titanate 0.5 part.

[0038] The plasticizer is carboxymethyl cellulose with a mass concentration of 15%.

[0039] The whiskers are zirconium oxide whiskers.

[0040] The Al2O3-ZrO2 / whisker composition is composed of Al2O3, ZrO2, and zirconium oxide whiskers in a weight ratio of 1:0.05:0.005.

[0041] The high thermal shock alumina composite ceramic is prepared by the following steps:

[0042] S1. Mix Al2O3, ZrO2 and whiskers to obtain a primary mixed powder for later use;

[0043] S2. Add the low thermal expansion coefficient base material to the primary mixed powder obtained in step S1 and mix and stir evenly to obtain a secondary mixed powder for later use;

[0044] S3. Add the secondary mixed powder obtained in step S2 to deionized water, and then add the plasticizer and mix evenly to obtain a mixed slurry for later use;

[0045] S4, preparing granulated powder by centrifugal spray granulation of the mixed slurry obtained in step S3, and setting aside;

[0046] S5, using isostatic pressing to form a ceramic tube blank from the granulated powder obtained in step S4, and set aside;

[0047] S6. The ceramic tube blank obtained in step S5 is placed at a temperature of 1100° C. and sintered independently for 3 hours in an air sintering manner to obtain a sintered ceramic tube blank for later use;

[0048] S7, cutting and cylindrically grinding the ceramic blank tube obtained in step S6 to obtain a ceramic tube formed in one step; and setting aside;

[0049] S8. Place the ceramic round tube obtained in step S7 at a temperature of 1550° C. for secondary sintering and independently keep the temperature for 2 hours. The sintering method is air sintering to obtain an alumina composite ceramic round tube.

[0050] In step S1, the average particle size D50 of Al2O3 is 2 μm, and the purity is ≥99.9%; the average particle size D50 of ZrO2 is 2 μm, and the purity is ≥94%.

[0051] Wherein, high-energy ball milling is used for mixing in step S3, the rotation speed during ball milling is 200 r / min, and the ball milling mixing time is 24 h.

[0052] In the centrifugal spray granulation in step S4, the inlet air temperature is 250° C., the outlet air temperature is 90° C., the centrifugal frequency is 130 Hz, and the feeding speed is 55 r / min.

[0053] The particle size of the granulated powder in step S4 is mainly distributed between 80-300 meshes.

[0054] The isostatic pressing pressure in step S5 is 100 MPa, the temperature is 80° C., and the holding time is 1500 s.

[0055] The temperature rise curve of step S6 is 20-600°C, the temperature rise rate is 0.5°C / min, and the temperature is kept for 1 hour; the temperature rise rate from 600 to 1100°C is 1°C / min, and the temperature is kept for 3 hours.

[0056] Among them, the heating curve of step S8 is room temperature-600℃, heating rate is 0.5℃ / min, keeping warm for 1h, 600-1200℃ heating rate is 1℃ / min, keeping warm for 1h, 1200-1550℃ heating rate is 1℃ / min, keeping warm for 2h.

[0057] Example 2

[0058] A high thermal shock alumina composite ceramic comprises the following raw materials in parts by weight: 80 parts of an Al2O3-ZrO2 / ceramic fiber composition, 150 parts of deionized water, 10 parts of a plasticizer, and 8 parts of a low thermal expansion coefficient base material.

[0059] The low thermal expansion coefficient base material includes Mg2Al4Si5O 18 3 parts, 3Al2O3·2SiO2 3 parts, MgO 0.5 parts, Al2[SiO4]O 1.5 parts and aluminum titanate 1.5 parts.

[0060] The plasticizer is a PVA plasticizer with a mass percentage of 8%.

[0061] The ceramic fiber is zirconia fiber.

[0062] The Al2O3-ZrO2 / ceramic fiber composition is composed of Al2O3, ZrO2, and zirconia fiber in a weight ratio of 1:0.2:0.03.

[0063] The high thermal shock alumina composite ceramic is prepared by the following steps:

[0064] S1. Mix Al2O3, ZrO2 and ceramic fiber to obtain a primary mixed powder for later use;

[0065] S2. Add the low thermal expansion coefficient base material to the primary mixed powder obtained in step S1 and mix and stir evenly to obtain a secondary mixed powder for later use;

[0066] S3. Add the secondary mixed powder obtained in step S2 to deionized water, and then add the plasticizer and mix evenly to obtain a mixed slurry for later use;

[0067] S4, preparing granulated powder by centrifugal spray granulation of the mixed slurry obtained in step S3, and setting aside;

[0068] S5, using isostatic pressing to form a ceramic tube blank from the granulated powder obtained in step S4, and set aside;

[0069] S6. The ceramic tube blank obtained in step S5 is placed at a temperature of 1200° C. and sintered independently for 2 hours in an air sintering manner to obtain a sintered ceramic tube blank for later use;

[0070] S7, cutting and cylindrically grinding the ceramic blank tube obtained in step S6 to obtain a ceramic tube formed in one step; and setting aside;

[0071] S8. Place the ceramic round tube obtained in step S7 at a temperature of 1600° C. and perform secondary sintering independently for 1 hour. The sintering method is air sintering to obtain an alumina composite ceramic round tube.

[0072] In step S1, the average particle size D50 of Al2O3 is 5 μm, and the purity is ≥99.9%; the average particle size D50 of ZrO2 is 4 μm, and the purity is ≥94%.

[0073] Wherein, high-energy ball milling is used for mixing in step S3, the rotation speed during ball milling is 250 r / min, and the ball milling mixing time is 21 h.

[0074] In the centrifugal spray granulation in step S4, the inlet air temperature is 280° C., the outlet air temperature is 120° C., the centrifugal frequency is 110 Hz, and the feeding speed is 35 r / min.

[0075] The particle size of the granulated powder in step S4 is mainly distributed between 80-300 meshes.

[0076] The isostatic pressing pressure in step S5 is 150 MPa, the temperature is 70° C., and the holding time is 900 s.

[0077] The temperature rise curve of step S6 is 20-600°C, the temperature rise rate is 0.5°C / min, and the temperature is kept for 1 hour; the temperature rise rate from 600 to 1200°C is 1°C / min, and the temperature is kept for 2 hours.

[0078] Among them, the heating curve of step S8 is room temperature-600℃, heating rate is 0.5℃ / min, keeping warm for 1h, heating rate from 600-1200℃ is 1℃ / min, keeping warm for 1h, heating rate from 1200-1600℃ is 1℃ / min, keeping warm for 1h.

[0079] Example 3

[0080] A high thermal shock alumina composite ceramic comprises the following raw materials in parts by weight: 95 parts of an Al2O3-ZrO2 / ceramic fiber composition, 200 parts of deionized water, 12 parts of a plasticizer, and 15 parts of a low thermal expansion coefficient base material.

[0081] The low thermal expansion coefficient base material includes Mg2Al4Si5O 18 5 parts, 3Al2O3·2SiO2 5 parts, MgO 1 part, Al2[SiO4]O 2 parts and aluminum titanate 2 parts.

[0082] The plasticizer is carboxymethyl cellulose with a mass concentration of 30%.

[0083] The ceramic fiber is zirconia fiber.

[0084] The Al2O3-ZrO2 / ceramic fiber composition is composed of Al2O3, ZrO2, and zirconia fiber in a weight ratio of 1:0.3:0.05.

[0085] The high thermal shock alumina composite ceramic is prepared by the following steps:

[0086] S1. Mix Al2O3, ZrO2 and ceramic fiber to obtain a primary mixed powder for later use;

[0087] S2. Add the low thermal expansion coefficient base material to the primary mixed powder obtained in step S1 and mix and stir evenly to obtain a secondary mixed powder for later use;

[0088] S3. Add the secondary mixed powder obtained in step S2 to deionized water, and then add the plasticizer and mix evenly to obtain a mixed slurry for later use;

[0089] S4, preparing granulated powder by centrifugal spray granulation of the mixed slurry obtained in step S3, and setting aside;

[0090] S5, using isostatic pressing to form a ceramic tube blank from the granulated powder obtained in step S4, and set aside;

[0091] S6. The ceramic tube blank obtained in step S5 is placed at a temperature of 1300° C. and sintered independently for 3 hours in an air sintering manner to obtain a sintered ceramic tube blank for later use;

[0092] S7, cutting and cylindrically grinding the ceramic blank tube obtained in step S6 to obtain a ceramic tube formed in one step; and setting aside;

[0093] S8. Place the ceramic round tube obtained in step S7 at a temperature of 1650° C. for secondary sintering and independently keep the temperature for 2 hours. The sintering method is air sintering to obtain an alumina composite ceramic round tube.

[0094] In step S1, the average particle size D50 of Al2O3 is 8 μm, and the purity is ≥99.9%; the average particle size D50 of ZrO2 is 5 μm, and the purity is ≥94%.

[0095] Wherein, high-energy ball milling is used for mixing in step S3, the rotation speed during ball milling is 300 r / min, and the ball milling mixing time is 24 h.

[0096] In the centrifugal spray granulation in step S4, the inlet air temperature is 300° C., the outlet air temperature is 140° C., the centrifugal frequency is 130 Hz, and the feeding speed is 55 r / min.

[0097] The particle size of the granulated powder in step S4 is mainly distributed between 80-300 meshes.

[0098] The isostatic pressing pressure in step S5 is 200 MPa, the temperature is 80° C., and the holding time is 1500 s.

[0099] The temperature rise curve of step S6 is 20-600°C, the temperature rise rate is 0.5°C / min, and the temperature is kept for 1 hour; the temperature rise rate from 600 to 1300°C is 1°C / min, and the temperature is kept for 3 hours.

[0100] Among them, the heating curve of step S8 is room temperature-600℃, heating rate is 0.5℃ / min, keeping warm for 1h, heating rate from 600-1200℃ is 1℃ / min, keeping warm for 1h, heating rate from 1200-1650℃ is 1℃ / min, keeping warm for 2h.

[0101] Comparative Example 1

[0102] The difference between this comparative example and the above-mentioned Example 2 is that ZrO2 is not added to the raw materials of this comparative example. The rest of the contents of this comparative example are the same as those of Example 2 and will not be repeated here.

[0103] Comparative Example 2

[0104] The difference between this comparative example and the above-mentioned Example 2 is that ZrO2 and ceramic fibers are not added to the raw materials of this comparative example for secondary toughening. The rest of the contents of this comparative example are the same as those of Example 2 and will not be repeated here.

[0105] Comparative Example 3

[0106] The difference between this comparative example and the above-mentioned embodiment 2 is that in step S3 of preparing the alumina composite ceramic tube, this comparative example adopts a drum ball milling method for mixing. The rest of the contents of this comparative example are the same as those of embodiment 2 and will not be repeated here.

[0107] Comparative Example 4

[0108] The difference between this comparative example and the above-mentioned Example 2 is that: no low thermal expansion coefficient base material is added to the raw materials of this comparative example. The rest of the contents of this comparative example are the same as those of Example 2 and will not be repeated here.

[0109] The performance of the alumina composite ceramics obtained in Example 2 and Comparative Examples 1-4 was tested, and the results are shown in Table 1:

[0110] The thermal expansion coefficient adopts GB / T 16535-2008 standard, the bending strength adopts GB / T 6569-2006 standard, and the hot and cold shock adopts GB / T3810.9 standard.

[0111] Table 1

[0112]

[0113] The above test data demonstrates that the alumina composite ceramic of the present invention exhibits high thermal shock resistance, low thermal expansion coefficient, and high flexural strength. Ceramic tubes made from this composite ceramic meet high thermal shock resistance requirements and can be widely used in environments with sudden temperature fluctuations. This indicates that using an Al2O3-ZrO2 / ceramic fiber or whisker combination in the raw materials for the alumina composite ceramic provides a secondary toughening effect, while adding a low thermal expansion coefficient base material and employing high-energy ball milling provide the best results.

[0114] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the scope of protection of the present invention.

Claims

1. A high thermal shock resistance alumina composite ceramic, characterized by: The invention comprises the following raw materials in parts by weight: 65-95 parts of an Al2O3-ZrO2 / ceramic fiber or whisker composition, 100-200 parts of deionized water, 8-12 parts of a plasticizer, and 2-15 parts of a low thermal expansion coefficient base material; the ceramic fiber or whisker comprises at least one of zirconium oxide fiber or whisker, magnesium oxide fiber or whisker, silicon carbide fiber or whisker, and silicon nitride fiber or whisker; the Al2O3-ZrO2 / ceramic fiber or whisker composition comprises Al2O3, ZrO2, and ceramic fiber or whisker in a weight ratio of 1:0.05-0.3:0.005-0.05; the low thermal expansion coefficient base material is Mg2Al4Si5O 18 3 parts, 3Al2O3·2SiO2 3 parts, MgO 0.5 parts, Al2[SiO4]O 1.5 parts and aluminum titanate 1.5 parts.

2. The high thermal shock resistance alumina composite ceramic according to claim 1, characterized in that: The plasticizer is at least one of carboxymethyl cellulose with a mass concentration of 15-30% and PVA plasticizer with a mass concentration of 8-20%.

3. A method for preparing the high thermal shock resistance alumina composite ceramic according to any one of claims 1 to 2, characterized in that: The steps include: S1. Mix Al2O3, ZrO2, and ceramic fibers or whiskers to obtain a primary mixed powder for later use; S2. Add the low thermal expansion coefficient base material to the primary mixed powder obtained in step S1 and mix and stir evenly to obtain a secondary mixed powder for later use; S3. Add the secondary mixed powder obtained in step S2 to deionized water, and then add the plasticizer and mix evenly to obtain a mixed slurry for later use; S4, preparing granulated powder by centrifugal spray granulation of the mixed slurry obtained in step S3, and setting aside; S5, forming a ceramic tube blank by dry pressing or isostatic pressing the granulated powder obtained in step S4, and setting aside; S6. The ceramic tube blank obtained in step S5 is placed at a temperature of 1100-1300° C. and sintered independently for 1-3 hours using air sintering to obtain a sintered ceramic tube blank for later use. S7, cutting and cylindrically grinding the ceramic blank tube obtained in step S6 to obtain a ceramic tube formed in one step; and setting aside; S8. Place the ceramic round tube obtained in step S7 at a temperature of 1550-1650° C. and perform secondary sintering independently for 0.5-2 hours. The sintering method is air sintering to obtain an alumina composite ceramic round tube.

4. The method for preparing a high thermal shock resistance alumina composite ceramic according to claim 3, wherein: In step S3, high-energy ball milling is used for mixing, the rotation speed during ball milling is 200-300 r / min, and the ball milling mixing time is 18-24 h.

5. The method for preparing a high thermal shock resistance alumina composite ceramic according to claim 3, characterized in that: During the centrifugal spray granulation in step S4, the inlet air temperature is 250-300°C, the outlet air temperature is 90-140°C, the centrifugal frequency is 90-130 Hz, and the feeding speed is 15-55 r / min.

6. The method for preparing a high thermal shock resistance alumina composite ceramic according to claim 3, characterized in that: The particle size of the granulated powder in step S4 is concentrated between 80-300 meshes; the isostatic pressing pressure in step S5 is 100-200 MPa, the temperature is 60-80° C., and the holding time is 300-1500 s.

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