Preparation method of high-strength alumina hollow sphere porous ceramic based on titanium sol coating

Abstract

The invention belongs to the technical field of preparation of aluminum oxide porous ceramics, and discloses a preparation method of high-strength aluminum oxide hollow sphere porous ceramics based on titanium sol coating, and the preparation method comprises the following specific steps: step 1, preparation of a titanium sulfate solution: slowly adding titanium sulfate into deionized water; through improved coating and drying processes, the prepared ceramic material shows higher uniformity in the aspects of porosity and pore size distribution, not only is the long-term durability of the material improved, but also the reliability of the material under high-temperature and dynamic loading conditions is enhanced, the application field is further widened, and meanwhile, in the high-temperature sintering process, the service life of the ceramic material is prolonged. The reaction between the titanium sol and the aluminum oxide hollow sphere matrix generates an aluminum titanate phase, and the phase is uniformly distributed in gaps among the aluminum oxide hollow spheres, so that the binding force of the aluminum oxide hollow spheres is remarkably improved, the overall mechanical property of the material is effectively enhanced, and the requirement of modern engineering application on the high-strength aluminum oxide porous ceramic is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of alumina porous ceramics, and specifically relates to a method for preparing high-strength alumina hollow sphere porous ceramics based on titania sol coating. Background Technique

[0002] Alumina hollow sphere porous ceramics have received extensive attention in the fields of aerospace, metallurgy, chemical engineering, etc. due to their low density, high strength, and excellent high-temperature resistance. These advantages enable this material to perform well in high-temperature or harsh environments and meet the strict requirements of modern technologies for material properties.

[0003] However, traditional preparation methods face many challenges in improving the strength of ceramics. Firstly, the mechanical strength of alumina hollow spheres themselves is usually low, resulting in the difficulty for the finally prepared porous ceramics to meet specific application standards in terms of load-bearing capacity and structural stability. In addition, existing sintering processes often lead to uneven distribution of ceramic porosity and unsatisfactory pore diameters, which directly restricts their mechanical properties and long-term durability. Therefore, how to improve its mechanical properties while retaining the required porous characteristics has become a major problem in current technology. Although some modification methods, such as the addition of environmentally friendly composite materials or selective laser sintering, attempt to enhance the strength of alumina porous ceramics through physical and chemical means, these methods often complicate the preparation process, increase costs, and affect the stability of the process, thus limiting their wide promotion in practical applications. Aluminum titanate, as a potential reinforcing material, is expected to significantly improve the comprehensive mechanical properties of alumina porous ceramics due to its excellent thermal stability and thermal shock resistance. However, the effective introduction and uniform distribution of aluminum titanate are still the key to technological breakthroughs. In many cases, the dispersibility of aluminum titanate particles in the alumina matrix is insufficient, resulting in poor interfacial bonding of the composite material and unable to fully exert its potential strengthening effect. Therefore, developing a new method that can achieve uniform coating and effective bonding of aluminum titanate has become an important way to improve the performance of porous alumina hollow sphere ceramics. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing high-strength alumina hollow sphere porous ceramics based on titania sol coating to solve the problems raised in the above background technique.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A method for preparing high-strength alumina hollow sphere porous ceramics based on titania sol coating, the specific steps are as follows:

[0006] Step 1: Preparation of titanium sulfate solution

[0007] Slowly add titanium sulfate to deionized water and stir until the titanium sulfate is completely dissolved to obtain a titanium sulfate solution;

[0008] Step 2: Addition of Ammonia Water and Coating of Titanium Sol

[0009] Immerse the alumina hollow spheres into the titanium sulfate solution in Step 1, and use a magnetic stirrer to stir evenly. During the stirring process, add ammonia water drop by drop to adjust the pH value of the mixed solution to 5 - 9, so as to promote the uniform coating of titanium sol on the surface of the alumina hollow spheres;

[0010] Step 3: Molding and Drying of Ceramic Green Body

[0011] Put the alumina hollow spheres coated with titanium sol into a mold, then transfer the mold to a forced air drying oven for drying treatment. After drying is completed, gently take out the mold for demolding to obtain a ceramic green body;

[0012] Step 4: High - temperature Sintering

[0013] Perform high - temperature sintering on the dried ceramic green body. After sintering is completed, wait for it to cool to room temperature to finally obtain high - strength porous ceramic of alumina hollow spheres.

[0014] Preferably, in the titanium sulfate solution in Step 1, the mass ratio of titanium sulfate to deionized water is 1:(10 - 20).

[0015] Preferably, the mass ratio of the titanium sulfate solution in Step 1 to the alumina hollow spheres is 1:(5 - 10).

[0016] Preferably, when adding ammonia water in Step 2, it needs to be added at a uniform speed, and the mass fraction concentration of ammonia water is 5% - 10%.

[0017] Preferably, the D 50 diameter of the alumina hollow spheres in Step 2 is 100 - 400 μm, and the bulk density is 0.4 - 1.2 g / cm 3 .

[0018] Preferably, the temperature of the drying treatment in Step 3 is 50 - 80 °C, and the drying time is 4 - 8 h.

[0019] Preferably, the high - temperature sintering temperature in Step 4 is 1300 - 1650 °C, the heat - preservation time is 1 - 4 h, the heating rate is 2 - 5 °C / min, and the cooling rate is 8 - 15 °C / min.

[0020] Preferably, the titanium sulfate in Step 1 needs to be fully stirred to ensure that the titanium sulfate is completely dissolved and the solution is uniform without precipitation.

[0021] Preferably, the mold in Step 3 needs to be adapted to the alumina hollow spheres to ensure that the shape of the ceramic green body is regular and easy to demold.

[0022] The beneficial effects of the present invention are as follows:

[0023] Through an improved coating and drying process, the prepared ceramic material exhibits higher uniformity in terms of porosity and pore size distribution. This not only enhances the long-term durability of the material but also improves its reliability under high-temperature and dynamic load conditions, further expanding the application fields. Meanwhile, during the high-temperature sintering process, the reaction between the titania sol and the alumina hollow sphere matrix generates the aluminum titanate phase, which is uniformly distributed in the gaps between the alumina hollow spheres, significantly improving their bonding strength and effectively enhancing the overall mechanical properties of the material to meet the requirements of modern engineering applications for high-strength alumina porous ceramics. Moreover, the titania sol coating technology simplifies the traditional preparation process, avoids complications and high costs, and realizes a sustainable and economical production method. This method not only speeds up the production efficiency but also meets the urgent requirements of modern industry for environmental protection and efficient resource utilization, showing broad market application potential. Description of the Drawings

[0024] Figure 1 SEM photos of the porous alumina hollow sphere ceramics prepared in Example 1 magnified 50× and 1000×;

[0025] Figure 2 SEM photos of the porous alumina hollow sphere ceramics prepared in Example 2 of the present invention magnified 50× and 500×;

[0026] Figure 3 SEM photos of the porous alumina hollow sphere ceramics prepared in Example 3 of the present invention magnified 50× and 500×. Detailed Embodiments

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] Example 1

[0029] As Figures 1 to 3 shown, the embodiment of the present invention provides a preparation method for high-strength porous alumina hollow sphere ceramics based on titania sol coating, and the specific steps are as follows:

[0030] Step 1: Preparation of titanium sulfate solution

[0031] Slowly add 200 g of titanium sulfate to 2000 mL of deionized water and stir until the titanium sulfate is completely dissolved to obtain a titanium sulfate solution;

[0032] Step 2: Addition of ammonia water and coating of titania sol

[0033] Immerse 500 g of D 50 with a diameter of 200 μm and a bulk density of 0.8 g / cm 3 aluminum oxide hollow spheres into the titanium sulfate solution in Step 1, and use a magnetic stirrer to stir evenly. During the stirring process, gradually add 25 mL of ammonia water with a mass fraction of 5% drop by drop to adjust the pH value of the mixed solution to 7, so as to promote the uniform coating of titanium sol on the surface of the aluminum oxide hollow spheres;

[0034] Step 3: Molding and drying of the ceramic green body

[0035] Put the aluminum oxide hollow spheres coated with titanium sol into a mold, and then transfer the mold to a blast drying oven set at a temperature of 60 °C for drying treatment. The drying time is 3 h. After drying is completed, gently take out the mold for demolding to obtain the ceramic green body;

[0036] Step 4: High-temperature sintering

[0037] Perform high-temperature sintering on the dried ceramic green body. Heat it to 1600 °C at a heating rate of 2.5 °C / min and hold for 3 h, and gradually cool it to room temperature at a cooling rate of 10 °C / min to finally obtain high-strength porous ceramics of aluminum oxide hollow spheres.

[0038] The performance parameters of the high-strength porous ceramics of aluminum oxide hollow spheres coated with titanium sol prepared in Example 1 are as follows: bulk density 2.1 g / cm 3 , apparent porosity is 39.4%, linear shrinkage rate is 7.1%, compressive strength is 32.1 MPa. The SEM photograph of the sample prepared in Example 1 is as shown in the Figure 1 in the figure. In this image, the aluminum oxide hollow spheres show a relatively uniform distribution, but it is observed that the contact area of the sintering necks (the area circled by the orange dotted line) between them is relatively small.

[0039] Among them, in the titanium sulfate solution in Step 1, the mass ratio of titanium sulfate to deionized water is 1:(10 - 20).

[0040] By adjusting the mass ratio of titanium sulfate to deionized water, ensure that titanium sulfate can be fully dissolved in deionized water, and the concentration of the formed titanium sulfate solution is appropriate. Such a concentration range helps to promote the stable formation of titanium sol in the subsequent steps.

[0041] Among them, the mass ratio of the titanium sulfate solution to the aluminum oxide hollow spheres in Step 1 is 1:(5 - 10).

[0042] By adjusting the mass ratio of the titanium sulfate solution and the alumina hollow spheres, it is ensured that there is enough titanium sol to uniformly and fully cover the entire surface of the alumina hollow spheres. This not only enhances the bonding force between the titanium sol and the alumina hollow spheres, but also improves the bonding property between the alumina hollow spheres.

[0043] Among them, when adding ammonia water in step two, it needs to be added at a constant speed, and the mass fraction concentration of ammonia water is 5% - 10%.

[0044] By selecting ammonia water with a mass fraction concentration of 5% - 10%, the hydrolysis and precipitation reaction process of the titanium sol can be effectively regulated, so that a more uniform and dense coating is formed on the surface of the alumina hollow spheres, thereby ensuring that the finally prepared high-strength alumina hollow sphere porous ceramics have excellent physical properties and structural stability.

[0045] Among them, the D 50 diameter of the alumina hollow spheres in step two is 100 - 400 μm, and the bulk density is 0.4 - 1.2 g / cm 3 .

[0046] By selecting alumina hollow spheres with a D 50 diameter of 100 - 400 μm and a bulk density of 0.412 g / cm 3 , it is ensured that they have excellent fluidity in the titanium sulfate solution, which is beneficial to the uniform coating of the titanium sol, optimizes the efficiency of the coating process, enables the titanium sol to quickly and fully cover the surface of the alumina hollow spheres, and ensures that the finally prepared high-strength alumina hollow sphere porous ceramics not only maintain high-efficiency preparation, but also have excellent physical properties and structural stability.

[0047] Among them, the temperature of the drying treatment in step three is 50 - 80 °C, and the drying time is 4 - 8 h.

[0048] By setting the temperature and drying time of the drying treatment, it can be ensured that the water on the alumina hollow spheres coated with titanium sol is uniformly and effectively removed during the drying process, which not only avoids the generation of surface defects such as cracks and depressions after demolding caused by water residue, but also further promotes the tight bonding between the titanium sol coating and the surface of the alumina hollow spheres.

[0049] Among them, the high-temperature sintering temperature in step four is 1300 - 1650 °C, the heat preservation time is 1 - 4 h, the heating rate is 2 - 5 °C / min, and the cooling rate is 8 - 15 °C / min.

[0050] By setting the sintering temperature, holding time, heating rate, and cooling rate, the interaction between alumina and aluminum titanate can be promoted, forming a denser ceramic structure, thereby enhancing the compressive strength and heat resistance of the prepared ceramic. At the same time, this can also prevent the decomposition of aluminum titanate at high temperatures and the appearance of microcracks during the cooling process.

[0051] Among them, the titanium sulfate in Step 1 needs to be fully stirred to ensure complete dissolution of the titanium sulfate, and the solution is uniform without precipitation.

[0052] After the titanium sulfate is completely dissolved, the formed solution is more uniform, which is beneficial to the subsequent coating process on the surface of alumina hollow spheres. The uniform solution can reduce the non-uniformity during the coating process and improve the consistency of the coating quality and thickness.

[0053] Among them, the mold in Step 3 needs to be adapted to the alumina hollow spheres to ensure that the ceramic green body has a regular shape and is easy to demold.

[0054] The adapted mold can ensure that the ceramic green body maintains a regular shape during the forming process, avoiding deformation or damage. At the same time, it can improve production efficiency and reduce production costs.

[0055] Example 2

[0056] As Figures 1 to 3 shown, the embodiment of the present invention provides a preparation method of a high-strength alumina hollow sphere porous ceramic based on titanium sol coating, and the specific steps are as follows:

[0057] Step 1: Preparation of titanium sulfate solution

[0058] Slowly add 150 g of titanium sulfate to 1500 mL of deionized water, and stir until the titanium sulfate is completely dissolved to obtain a titanium sulfate solution;

[0059] Step 2: Addition of ammonia water and coating of titanium sol

[0060] Immerse 600 g of D 50 alumina hollow spheres with a diameter of 350 μm and a bulk density of 0.5 g / cm 3 into the titanium sulfate solution in Step 1, and use a magnetic stirrer to stir evenly. During the stirring process, gradually add 60 mL of ammonia water with a mass fraction of 15% to adjust the pH value of the mixed solution to 6 to promote the uniform coating of titanium sol on the surface of the alumina hollow spheres;

[0061] Step 3: Forming and drying of the ceramic green body

[0062] Put the alumina hollow spheres coated with titanium sol into a mold, and then transfer the mold to a forced-air drying oven set at 50 °C for drying treatment. The drying time is 4 h. After drying is completed, gently take out the mold for demolding to obtain a ceramic green body;

[0063] Step 4: High-temperature sintering

[0064] Perform high-temperature sintering on the dried ceramic green body, heat it to 1600 °C at a heating rate of 3 °C / min and hold for 3 h, and gradually cool it to room temperature at a cooling rate of 10 °C / min to finally obtain high-strength alumina hollow sphere porous ceramics.

[0065] The performance parameters of the high-strength alumina hollow sphere porous ceramics prepared in Example 2 based on titanium sol coating are as follows: bulk density 2.7 g / cm 3 , apparent porosity is 24.5%, linear shrinkage rate is 4.2%, compressive strength is 56 MPa. The SEM photograph of the sample prepared in Example 2 is as shown in the Figure 2 instruction manual. It is observed that the contact area of the sintering necks (the area circled by the orange dotted line) between the alumina hollow spheres has increased, showing improvement compared with Example 1.

[0066] Among them, in the titanium sulfate solution in Step 1, the mass ratio of titanium sulfate to deionized water is 1:(10 - 20).

[0067] By adjusting the mass ratio of titanium sulfate to deionized water, it is ensured that titanium sulfate can be fully dissolved in deionized water, and the concentration of the formed titanium sulfate solution is appropriate. Such a concentration range helps to promote the stable formation of titanium sol in the subsequent steps.

[0068] Among them, the mass ratio of the titanium sulfate solution to the alumina hollow spheres in Step 1 is 1:(5 - 10).

[0069] By adjusting the mass ratio of the titanium sulfate solution to the alumina hollow spheres, it is ensured that there is enough titanium sol to uniformly and fully cover the entire surface of the alumina hollow spheres, which not only enhances the bonding force between the titanium sol and the alumina hollow spheres but also improves the bonding property between the alumina hollow spheres.

[0070] Among them, when adding ammonia water in Step 2, it needs to be added at a constant speed, and the mass fraction concentration of ammonia water is 5% - 10%.

[0071] By selecting ammonia water with a mass fraction concentration of 5% - 10%, the hydrolysis and precipitation reaction process of titanium sol can be effectively regulated, so that a more uniform and dense coating is formed on the surface of the alumina hollow spheres, thus ensuring that the finally prepared high-strength alumina hollow sphere porous ceramics have excellent physical properties and structural stability.

[0072] Among them, in step two, the D of the alumina hollow spheres 50 has a diameter of 100 - 400 μm and a bulk density of 0.4 - 1.2 g / cm 3 .

[0073] By selecting alumina hollow spheres with a D 50 diameter of 100 - 400 μm and a bulk density of 0.4 - 1.2 g / cm 3 , it is ensured that they have excellent fluidity in the titanium sulfate solution, which is conducive to the uniform coating of the titania sol, optimizing the efficiency of the coating process, enabling the titania sol to quickly and fully cover the surface of the alumina hollow spheres, and ensuring that the finally prepared high-strength alumina hollow sphere porous ceramics not only maintain high-efficiency preparation but also have excellent physical properties and structural stability.

[0074] Among them, in step three, the temperature of the drying treatment is 50 - 80 °C and the drying time is 4 - 8 h.

[0075] By setting the temperature and time of the drying treatment, it can ensure that the water in the alumina hollow spheres coated with titania sol is removed uniformly and effectively during the drying process, not only avoiding the generation of surface defects such as cracks and depressions after demolding caused by water residue, but also further promoting the tight bonding between the titania sol coating and the surface of the alumina hollow spheres.

[0076] Among them, in step four, the high-temperature sintering temperature is 1300 - 1650 °C, the holding time is 1 - 4 h, the heating rate is 2 - 5 °C / min, and the cooling rate is 8 - 15 °C / min.

[0077] By setting the sintering temperature, holding time, heating rate, and cooling rate, it can promote the interaction between alumina and aluminum titanate, form a denser ceramic structure, thereby enhancing the compressive strength and heat resistance of the prepared ceramics. At the same time, this can also avoid the decomposition of aluminum titanate at high temperatures and the appearance of microcracks during the cooling process.

[0078] Among them, the titanium sulfate in step one needs to be fully stirred to ensure that the titanium sulfate is completely dissolved and the solution is uniform without precipitation.

[0079] After the titanium sulfate is completely dissolved, the formed solution is more uniform, which is conducive to the subsequent coating process on the surface of the alumina hollow spheres. The uniform solution can reduce the non-uniformity during the coating process and improve the consistency of the coating quality and thickness.

[0080] Among them, the mold in step three needs to be mutually adapted to the alumina hollow spheres to ensure that the shape of the ceramic green body is regular and easy to demold.

[0081] The adapted mold can ensure that the ceramic green body maintains a regular shape during the forming process, avoid deformation or breakage, improve production efficiency, and reduce production costs.

[0082] Example Three

[0083] As Figures 1 to 3 shown, the embodiment of the present invention provides a preparation method of high-strength alumina hollow sphere porous ceramics based on titanium sol coating. The specific steps are as follows:

[0084] Step 1: Preparation of titanium sulfate solution

[0085] Slowly add 250 g of titanium sulfate to 2500 mL of deionized water, and stir until the titanium sulfate is completely dissolved to obtain a titanium sulfate solution;

[0086] Step 2: Addition of ammonia water and coating of titanium sol

[0087] Immerse 500 g of D 50 alumina hollow spheres with a diameter of 250 μm and a bulk density of 0.6 g / cm 3 into the titanium sulfate solution in Step 1, and use a magnetic stirrer to stir evenly. During the stirring process, gradually add 40 mL of ammonia water with a mass fraction of 10% drop by drop to adjust the pH value of the mixed solution to 6.5 to promote the uniform coating of titanium sol on the surface of the alumina hollow spheres;

[0088] Step 3: Forming and drying of the ceramic green body

[0089] Put the alumina hollow spheres coated with titanium sol into a mold, then transfer the mold to a blast drying oven set at a temperature of 55°C for drying treatment. The drying time is 3 h. After drying is completed, gently take out the mold for demolding to obtain a ceramic green body;

[0090] Step 4: High-temperature sintering

[0091] Perform high-temperature sintering on the dried ceramic green body. Heat it to 1650°C at a heating rate of 2°C / min and hold for 2 h, and gradually cool it to room temperature at a cooling rate of 10°C / min to finally obtain high-strength alumina hollow sphere porous ceramics.

[0092] The performance parameters of the high-strength alumina hollow sphere porous ceramics based on titanium sol coating prepared in Example Three are as follows: bulk density 2.89 g / cm 3 , apparent porosity is 21%, linear shrinkage rate is 3.5%, compressive strength is 64.6 MPa. The SEM photograph of the sample prepared in Example Three is as shown in the attached Figure 3 of the specification, and in the attached Figure 3In [the situation], it can be observed that compared with Example 1 and Example 2, the contact area of the sintering necks (orange dotted line area) between the alumina hollow spheres has increased significantly.

[0093] Among them, in the titanium sulfate solution in Step 1, the mass ratio of titanium sulfate to deionized water is 1:(10 - 20).

[0094] By adjusting the mass ratio of titanium sulfate to deionized water, it is ensured that titanium sulfate can be fully dissolved in deionized water, and the concentration of the formed titanium sulfate solution is appropriate. Such a concentration range helps to promote the stable formation of titanium sol in the subsequent steps.

[0095] Among them, the mass ratio of the titanium sulfate solution to the alumina hollow spheres in Step 1 is 1:(5 - 10).

[0096] By adjusting the mass ratio of the titanium sulfate solution to the alumina hollow spheres, it is ensured that there is enough titanium sol to uniformly and fully cover the entire surface of the alumina hollow spheres. This not only enhances the bonding force between the titanium sol and the alumina hollow spheres but also improves the bonding property between the alumina hollow spheres.

[0097] Among them, when adding ammonia water in Step 2, it needs to be added at a constant speed, and the mass fraction concentration of ammonia water is 5% - 10%.

[0098] By selecting ammonia water with a mass fraction concentration of 5% - 10%, the hydrolysis and precipitation reaction process of titanium sol can be effectively regulated, so that a more uniform and dense coating is formed on the surface of the alumina hollow spheres, thus ensuring that the finally prepared high-strength alumina hollow sphere porous ceramics have excellent physical properties and structural stability.

[0099] Among them, in Step 2, the D 50 diameter of the alumina hollow spheres is 100 - 400 μm, and the bulk density is 0.4 - 1.2 g / cm 3 .

[0100] By selecting alumina hollow spheres with a D 50 diameter of 100 - 400 μm and a bulk density of 0.412 g / cm 3 , it is ensured that they have excellent fluidity in the titanium sulfate solution, which is conducive to the uniform coating of titanium sol, optimizing the efficiency of the coating process, enabling the titanium sol to quickly and fully cover the surface of the alumina hollow spheres, and ensuring that the finally prepared high-strength alumina hollow sphere porous ceramics not only maintain efficient preparation but also have excellent physical properties and structural stability.

[0101] Among them, the temperature of the drying treatment in Step 3 is 50 - 80 °C, and the drying time is 4 - 8 h.

[0102] By setting the temperature and drying time of the drying process, it is possible to ensure that the alumina hollow spheres coated with titania sol uniformly and effectively remove moisture during drying. This not only avoids the generation of surface defects after demolding caused by residual moisture, such as cracks and depressions, but also further promotes the tight bonding between the titania sol coating and the surface of the alumina hollow spheres.

[0103] Among them, in step four, the high-temperature sintering temperature is 1300 - 1650 °C, the heat preservation time is 1 - 4 h, the heating rate is 2 - 5 °C / min, and the cooling rate is 8 - 15 °C / min.

[0104] By setting the sintering temperature, heat preservation time, heating rate, and cooling rate, it is possible to promote the interaction between alumina and aluminum titanate, form a denser ceramic structure, thereby improving the compressive strength and heat resistance of the prepared ceramic. At the same time, this can also avoid the decomposition of aluminum titanate at high temperatures and the appearance of microcracks during the cooling process.

[0105] Among them, the titanium sulfate in step one needs to be fully stirred to ensure that the titanium sulfate is completely dissolved and the solution is uniform without precipitation.

[0106] After the titanium sulfate is completely dissolved, the formed solution is more uniform, which is beneficial to the subsequent coating process on the surface of the alumina hollow spheres. The uniform solution can reduce the non-uniformity during the coating process and improve the consistency of the coating quality and thickness.

[0107] Among them, the mold in step three needs to be adapted to the alumina hollow spheres to ensure that the ceramic green body has a regular shape and is easy to demold.

[0108] The adapted mold can ensure that the ceramic green body maintains a regular shape during the forming process, avoid deformation or breakage, and at the same time improve production efficiency and reduce production costs.

[0109] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0110] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating, characterized in that: The specific steps are as follows: Step 1: Preparation of titanium sulfate solution Slowly adding titanium sulfate into deionized water and stirring until the titanium sulfate is completely dissolved to obtain a titanium sulfate solution; Step 2: Addition of ammonia water and coating of titanium sol Immerse the hollow alumina spheres in the titanium sulfate solution in step 1, and stir evenly with a magnetic stirrer, add ammonia water dropwise during the stirring process, and adjust the pH value of the mixed solution to 5-9, so as to promote the titanium sol to be evenly coated on the surface of the hollow alumina spheres; Step 3: Forming and drying of the ceramic body The alumina hollow spheres coated with titanium sol are placed in a mold, and then the mold is transferred to a blast drying oven for drying. After drying, the mold is gently taken out for demoulding to obtain a ceramic body; Step 4: High temperature sintering The dried ceramic body is sintered at high temperature, and after sintering, it is cooled to room temperature to finally obtain high-strength alumina hollow sphere porous ceramics.

2. The method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating according to claim 1, characterized in that: In the titanium sulfate solution described in step 1, the mass ratio of titanium sulfate to deionized water is 1:(10-20).

3. The method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating according to claim 1, characterized in that: The mass ratio of the titanium sulfate solution to the hollow alumina spheres in step 1 is 1:(5-10).

4. The method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating according to claim 1, characterized in that: The ammonia water needs to be added at a uniform speed in step 2, and the mass fraction concentration of the ammonia water is 5%-10%.

5. The method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating according to claim 1, characterized in that: The D of the hollow alumina sphere in step 2 50 The diameter is 100-400 μm, and the bulk density is 0.4-1.2 g / cm 3 .

6. The method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating according to claim 1, characterized in that: The drying temperature in step 3 is 50-80° C. and the drying time is 4-8 hours.

7. The method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating according to claim 1, characterized in that: The high-temperature sintering temperature in step 4 is 1300-1650° C., the holding time is 1-4 hours, the heating rate is 2-5° C. / min, and the cooling rate is 8-15° C. / min.

8. The method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating according to claim 1, characterized in that: The titanium sulfate described in step 1 needs to be fully stirred to ensure that the titanium sulfate is completely dissolved and the solution is uniform without precipitation.

9. The method for preparing high-strength alumina hollow sphere porous ceramics based on titanium sol coating according to claim 1, characterized in that: The mold described in step three needs to be compatible with the hollow alumina sphere to ensure that the ceramic body has a regular shape and is easy to demold.

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