Porous ceramic filter plate and preparation method thereof
By controlling the addition ratio of chromium corundum and the sintering process, a high-performance porous ceramic filter plate was prepared, solving the problems of environmental pollution and sintering cracking, and realizing the resource utilization and cost reduction of chromium corundum.
Patent Information
- Application Number
- CN202511625874.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-07
- Publication Date
- 2026-01-13
AI Technical Summary
Improper disposal of chromium-containing waste in existing technologies has led to serious environmental pollution problems. At the same time, porous ceramic filter plates are prone to cracking during sintering, which affects product performance.
A ceramic wet blank was prepared by ball milling a mixture of potassium feldspar, kaolin, alumina, chromium corundum and surfactant, and then adding hydrogen peroxide. The wet blank was then prepared by gradient sintering to produce a porous ceramic filter plate. The addition ratio of chromium corundum and the sintering temperature were controlled to improve the porosity and compressive strength.
This method enables the resource utilization of chromium corundum, reduces the production cost of porous ceramic filter plates, solves the cracking problem during sintering, and yields high-performance porous ceramic filter plates.
Smart Images
Figure CN121318521A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of inorganic chemical engineering, and in particular to a porous ceramic filter plate and its preparation method. Background Technology
[0002] Porous ceramics, due to their unique porous structure, possess characteristics such as small volume, low density, large specific surface area, and low thermal conductivity. The inherent superior compressive strength, high-temperature resistance, corrosion resistance, and good chemical stability of porous ceramic materials have led to their widespread application in metallurgy, environmental protection, food, pharmaceuticals, chemicals, ecological environment, energy, and bioengineering, yielding significant economic and social benefits. Alumina, with its high hardness, high strength, corrosion resistance, low coefficient of thermal expansion, and wear resistance, is one of the most widely used ceramic materials in industry today. Alumina porous ceramics, combining the advantages of both alumina and porous ceramics, have broad application prospects. Previously, the improper disposal of chromium-containing waste caused significant environmental pollution problems, requiring a lengthy remediation and restoration process. In the past two decades, there have been frequent cases of hexavalent chromium pollution threatening public safety. Currently, methods for treating chromium corundum mainly include using it as a raw material for glassmaking, as a cement mineralizer, microbial detoxification, and as a substitute for dolomite sintering. However, it was not used to partially replace alumina in the preparation of porous ceramic plates. If added improperly, the porosity and compressive strength of the porous ceramic plate filter will be substandard, and it will also easily cause cracking during the sintering process.
[0003] Therefore, existing technologies still need to be improved and developed. Summary of the Invention
[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a porous ceramic filter plate and its preparation method, which aims to solve the environmental pollution problem caused by the unreasonable disposal of existing chromium-containing waste, and at the same time solve the cracking problem in the sintering process.
[0005] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing a porous ceramic filter plate, comprising the following steps: S1. Potassium feldspar, kaolin, alumina, chromium corundum, surfactant and water are ball-milled to obtain ceramic slurry; S2. The ceramic slurry is shaped and then hydrogen peroxide is added to form a wet ceramic blank; S3. The ceramic green body is dried and then subjected to gradient sintering to obtain the porous ceramic filter plate.
[0006] Optionally, the mass ratio of potassium feldspar, kaolin, alumina, and chromium corundum in S1 is 5:5-10:65-90:5-10.
[0007] Optionally, the mass of water in S1 is 0.5-0.7 times the total mass of potassium feldspar, kaolin, alumina, and chromium corundum.
[0008] Optionally, the surfactant is methylene phosphoric acid or potassium monododecyl phosphate.
[0009] Optionally, the amount of the surfactant used is 1-3%.
[0010] It should be noted that during ball milling, the ratio of large, medium, and small grinding balls is 2:3:5, the milling speed is 100 r / min, and the time is 4 h. Drying is carried out using a forced-air drying method at 60 ℃.
[0011] Optionally, the ratio of ceramic slurry to hydrogen peroxide is 80-100:1.
[0012] Optionally, gradient sintering involves heating from room temperature to 300-400℃ and holding for 20-50 min, then heating to 700-900℃ and holding for 20-50 min, and finally heating to 1350-1450℃ and holding for 50-70 min.
[0013] Secondly, the present invention provides a porous ceramic filter plate, which is prepared by the aforementioned preparation method.
[0014] Beneficial effects: This invention creatively replaces alumina with chromium corundum in the preparation of porous ceramics, and different proportions are added to obtain porous ceramics with optimal performance. This not only reduces the production cost of alumina porous ceramics and realizes the resource utilization of chromium corundum, but also solves the cracking problem in the preparation process of porous ceramic filter plates. Attached Figure Description
[0015] Figure 1 This is a flowchart illustrating the preparation of a porous ceramic filter plate according to an embodiment of the present invention.
[0016] Figure 2 This is the gradient sintering curve of an embodiment of the present invention.
[0017] Figure 3 X-ray powder diffraction patterns of porous ceramic filter plates with different chromium corundum contents.
[0018] Figure 4 SEM scans (100x magnification) of porous ceramic filter plates with different chromium corundum contents.
[0019] Figure 5 SEM scans of porous ceramic filter plates with different chromium corundum contents (magnified 2000 times).
[0020] Figure 6 The curve shows the relationship between the porosity and chromium corundum content of the porous ceramic filter plate.
[0021] Figure 7 The curve shows the relationship between the compressive strength of the porous ceramic filter plate and the chromium corundum content.
[0022] Figure 8 The curve shows the relationship between the compressive strength of a porous ceramic filter plate and its porosity. Detailed Implementation
[0023] This invention provides a porous ceramic filter plate and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0024] Existing methods for processing chromium corundum mainly include using it as a raw material for glassmaking, as a cement mineralizer, microbial detoxification, and as a substitute for dolomite in sintering. However, it has not been used to partially replace alumina in the preparation of porous ceramic plates. During experiments, the inventors discovered that improper addition would result in substandard porosity and compressive strength of the porous ceramic plate's filter plate, and would also easily cause cracking during sintering.
[0025] Based on this, this embodiment provides a method for preparing a porous ceramic filter plate, such as... Figure 1 As shown, it includes the following steps: S1. Potassium feldspar, kaolin, alumina, chromium corundum, surfactant and water are ball-milled to obtain ceramic slurry; S2. The ceramic slurry is shaped and then hydrogen peroxide is added to form a wet ceramic blank; S3. The ceramic green body is dried and then subjected to gradient sintering to obtain the porous ceramic filter plate.
[0026] This embodiment uses chromium corundum to partially replace alumina in the preparation of porous ceramic filter plates. On the one hand, this reduces the production cost of ceramic filter plates, and on the other hand, it utilizes hazardous waste chromium corundum as raw material to achieve the resource utilization of chromium corundum.
[0027] This embodiment utilizes the process of reducing chromium trioxide with aluminum powder to produce chromium corundum. The reduction of chromium trioxide by aluminum powder generates aluminum trioxide, which then forms a solid solution with chromium trioxide at high temperatures, resulting in chromium corundum. The main component of chromium corundum is aluminum trioxide. Using chromium corundum to partially replace alumina in the preparation of porous ceramic filter plates not only reduces production costs but, more importantly, allows for the resource utilization of hazardous waste chromium corundum. While chromium trioxide in chromium corundum enhances the hardness, wear resistance, and high-temperature resistance of aluminum trioxide, the high thermal expansion of chromium trioxide at high temperatures makes the porous ceramic filter plates prepared from it prone to cracking under high-temperature applications. Therefore, chromium corundum must be used to partially replace alumina in the preparation of porous ceramics to achieve good porosity and high compressive strength.
[0028] The chromium corundum of this embodiment comprises aluminum oxide: 74%, silicon dioxide: 4%, magnesium oxide: 1%, phosphorus pentoxide: 12%, chromium trioxide: 6%, zirconium dioxide: 2%, and sodium oxide: 1%.
[0029] In some embodiments, the mass ratio of potassium feldspar, kaolin, alumina, and chromium corundum in S1 is 5:5-10:65-90:5-10.
[0030] It should be noted that this ratio results in a filter plate with good porosity and high compressive strength, while also reducing the likelihood of cracking during sintering. Potassium feldspar lowers the sintering temperature and introduces a liquid phase during high-temperature sintering, which facilitates atomic diffusion and thus enhances strength. The addition of kaolin introduces silica, allowing it to form a solid solution with chromium trioxide, thereby stabilizing the crystal lattice and reducing the coefficient of thermal expansion, making it less prone to cracking under high-temperature applications. Only by using an appropriate ratio can the cracking of the sintered product be controlled.
[0031] In some embodiments, the mass ratio of potassium feldspar, kaolin, alumina, and chromium corundum in S1 is 5:10:75:10.
[0032] In some embodiments, the mass of water in S1 is 0.5-0.7 times the total mass of potassium feldspar, kaolin, alumina, and chromium corundum, preferably 0.6 times, but can also be 0.5 times or 0.7 times.
[0033] In some embodiments, the surfactant is methylene phosphoric acid or potassium monododecyl phosphate.
[0034] In some embodiments, the amount of the surfactant used is 1-3%.
[0035] It should be noted that during ball milling, the ratio of large, medium, and small grinding balls is 2:3:5, the milling speed is 100 r / min, and the time is 4 h. Drying is carried out using a forced-air drying method at 60 ℃.
[0036] In some embodiments, the ratio of ceramic slurry to hydrogen peroxide is 80-100:1.
[0037] In some embodiments, gradient sintering involves heating from room temperature to 300-400°C (e.g., 350°C), holding at that temperature for 20-50 min (e.g., 30 min), then further heating to 700-900°C (e.g., 800°C) and holding for 20-50 min (e.g., 30 min), followed by heating to 1350-1450°C (e.g., 1400°C) and holding for 50-70 min (e.g., 60 min). The sintering temperature profile is shown below. Figure 2 As shown.
[0038] Low-temperature slow firing can remove moisture from the green body without causing the sample to crack, high-temperature fast firing is to save energy and time and improve efficiency, and high-temperature heat preservation is to enable rapid atomic diffusion in the presence of a high-temperature liquid phase to improve the sample strength.
[0039] This embodiment provides a porous ceramic filter plate, which is prepared by the aforementioned preparation method.
[0040] The porous ceramic filter plate provided in this embodiment has a suitable porosity and high compressive strength.
[0041] The present invention will be further described below with reference to specific embodiments.
[0042] Example 1 Weigh out the raw materials according to the following mass ratio: 5 parts potassium feldspar, 5 parts kaolin, 85 parts alumina, and 5 parts chromium corundum. Place them in a ball mill jar, add 3 times the mass of the raw materials of zirconia grinding balls (large, medium, and small balls in a ratio of 2:3:5), weigh out 0.6 times the mass of the raw materials of purified water and add them to the ball mill jar, along with an appropriate amount of surfactant phosphite. Place the ball mill jar on a roller mill, adjust the speed to 100 r / min, and continuously ball mill in one direction for 4 hours. After ball milling, remove the sample, sieve to remove impurities, and obtain a uniformly mixed ceramic slurry. Add the ceramic slurry to a plastic mold for shaping, add 100 ml of hydrogen peroxide using a foaming method, and place the resulting wet blank in a drying oven and dry it with forced air at 60 ℃. The dried green blank was placed in a high-temperature box-type resistance furnace for sintering. The temperature was increased from room temperature to 350℃ at a rate of 3℃ / min and held for 30 min. Then, the temperature was increased to 800℃ at a rate of 3℃ / min and held for 30 min. Finally, the temperature was increased to 1400℃ at a rate of 5℃ / min and held for 60 min. The porous ceramic filter plate of this embodiment was thus obtained.
[0043] Example 2 Weigh out the raw materials according to the following mass ratio: 5 parts potassium feldspar, 10 parts kaolin, 75 parts alumina, and 10 parts chromium corundum. Place them in a ball mill jar, add 3 times the mass of the raw materials of zirconia grinding balls (the ratio of large, medium, and small grinding balls is 2:3:5), weigh out 0.6 times the mass of the raw materials of purified water and add them to the ball mill jar, along with an appropriate amount of surfactant methyl phosphonate. Place the ball mill jar on a roller mill, adjust the speed to 100 r / min, and continuously ball mill in one direction for 4 hours. After ball milling, remove the sample, sieve to remove impurities, and obtain a uniformly mixed ceramic slurry. Add the slurry to a plastic mold for shaping, add 100 ml of hydrogen peroxide using a foaming method, and place the resulting wet blank in a drying oven and dry it with forced air at 60 ℃. The dried green blank was placed in a high-temperature box-type resistance furnace and sintered according to the following conditions: 50℃-350℃, 3℃ / min, 350℃ for 30 min, 350℃-800℃, 3℃ / min, 800℃ for 30 min, 800℃-1400℃, 5℃ / min, 1400℃ for 60 min, to obtain the porous ceramic filter plate of this embodiment.
[0044] Comparative Example 1 The difference between this comparative example and Example 1 is that the raw materials were weighed and placed in a ball mill jar according to the mass ratio of potassium feldspar 10, kaolin 15, alumina (75) and chromium corundum (0).
[0045] Comparative Example 2 The difference between this comparative example and Example 1 is that potassium feldspar 10, kaolin 10, alumina (65) and chromium corundum (15) were weighed and placed into a ball mill jar.
[0046] Comparative Example 3 The difference between this comparative example and Example 1 is that potassium feldspar 10, kaolin 5, alumina (65), and chromium corundum (20) were weighed and placed into a ball mill jar.
[0047] Comparative Example 4 The difference between this comparative example and Example 1 is that potassium feldspar 5, kaolin 5, alumina (65), and chromium corundum (25) were weighed and placed into a ball mill jar.
[0048] The porous ceramic filter plates obtained in the above embodiments and comparative examples were subjected to X-ray powder diffraction, and the results are as follows: Figure 3 As shown, the porous ceramic filter plates prepared in Examples 1 and 2 have an alumina phase content that is predominantly present. Therefore, these porous ceramics have high compressive strength, ensuring the mechanical properties of the porous ceramic filter plates. The compressive strength of Comparative Example 1 is slightly lower than that of the Examples.
[0049] The porous ceramic filter plates obtained in the above embodiments and comparative examples were analyzed by scanning electron microscopy, and the results are as follows: Figure 4 , Figure 5 As shown, the porous ceramic filter plates in Examples 1 and 2 have smaller pore sizes, more uniform pore size distribution, better surface morphology, more alumina ceramic crystalline phases, better structure, and more uniform distribution. However, with the increase of chromium corundum content, the pore connectivity becomes worse, and the skeleton structure becomes denser. In Comparative Examples 2, 3, and 4, with the increase of chromium corundum content, the pore connectivity deteriorates, which is not conducive to the filtration of the ceramic plates.
[0050] The porosity and compressive strength of the porous ceramic filter plates obtained in the above embodiments and comparative examples were measured, and the results are as follows: Figure 6 , Figure 7 , Figure 8 As shown. Figure 6 As shown, with the increase of chromium slag content, the number of pores decreases, and the porosity continuously declines. The porosity of the prepared porous ceramics is between 70% and 90%. Figure 7 As shown, with the continuous increase of chromium corundum content, its compressive strength is higher and its compressive performance is stronger. This is because the introduction of chromium corundum makes the sintered ceramic more compact, the skeleton structure more dense, and the permeability of the channels worse, which is related to... Figure 6 The analysis results are consistent. For example... Figure 8 As shown in the figure, when the porosity of the porous ceramic filter plate increases, its mechanical strength decreases accordingly. It can be seen from the figure that the optimal addition amount of chromium corundum is 5%-10%, which is conducive to the resource utilization of chromium corundum and reduces the production cost of alumina porous ceramic filter plates.
[0051] In summary, this invention creatively replaces alumina with chromium corundum in the preparation of porous ceramics, and different proportions yield porous ceramics with optimal performance. This not only reduces the production cost of alumina porous ceramics and realizes the resource utilization of chromium corundum, but also solves the cracking problem in the preparation process of porous ceramic filter plates.
[0052] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A method for preparing a porous ceramic filter plate, characterized in that, Includes the following steps: S1. Potassium feldspar, kaolin, alumina, chromium corundum, surfactant and water are ball-milled to obtain ceramic slurry; S2. The ceramic slurry is shaped and then hydrogen peroxide is added to form a wet ceramic blank; S3. The ceramic green body is dried and then subjected to gradient sintering to obtain the porous ceramic filter plate.
2. The method for preparing a porous ceramic filter plate according to claim 1, characterized in that, In S1, the mass ratio of potassium feldspar, kaolin, alumina, and chromium corundum is 5:5-10:65-90:5-10.
3. The method for preparing a porous ceramic filter plate according to claim 1, characterized in that, In S1, the mass of water is 0.5-0.7 times the total mass of potassium feldspar, kaolin, alumina, and chromium corundum.
4. The method for preparing a porous ceramic filter plate according to claim 1, characterized in that, In S1, the surfactant is methylene phosphoric acid or potassium monododecyl phosphate.
5. The method for preparing a porous ceramic filter plate according to claim 1, characterized in that, In S1, the amount of the surfactant used is 1-3%.
6. The method for preparing a porous ceramic filter plate according to claim 1, characterized in that, In S2, the ratio of ceramic slurry to hydrogen peroxide is 80-100:
1.
7. The method for preparing a porous ceramic filter plate according to claim 1, characterized in that, In S3, the gradient sintering process involves heating from room temperature to 300-400℃ and holding for 20-50 min, then heating to 700-900℃ and holding for 20-50 min, and finally heating to 1350-1450℃ and holding for 50-70 min.
8. A porous ceramic filter plate, characterized in that, Prepared by the preparation method described in any one of claims 1-7.