A preparation method of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics

Abstract

The present invention relates to the technical field of porous ceramic preparation, and particularly to a preparation method of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics. In the present invention, a mixture of a magnesium source, an aluminum source, and a silicon source is subjected to primary ball milling and mixing. After the mixing is completed, a pore-forming agent is added for secondary ball milling and mixing to obtain a mixed material; the mixed material is pressed into a shape to obtain a green body; the green body is dried and then subjected to segmented sintering to obtain in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics. The present invention uses a method combining two-stage ball milling and mixing with segmented sintering to in-situ synthesize mullite whiskers. By adjusting the sintering process, the number, size, and distribution of the whiskers are controlled within a suitable range, thereby obtaining mullite whisker self-reinforced cordierite porous ceramics with high porosity and high strength. Moreover, the raw materials for preparation are widely sourced, the composition is easy to control, and the process is easy to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of porous ceramic preparation, and particularly relates to a preparation method of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramic. Background Art

[0002] Cordierite porous ceramic materials are widely used as catalyst carriers, filtration and separation materials, refractory materials, and electronic device materials due to their low thermal expansion coefficient, high porosity, good chemical stability, high temperature resistance, and large specific surface area. Usually, the higher the porosity of ceramics, the lower the mechanical properties. Therefore, the relatively high porosity of cordierite porous ceramics results in lower mechanical properties, which in turn limits their applications.

[0003] In-situ synthesis of mullite whiskers is one of the effective ways to enhance the mechanical properties of cordierite porous ceramics. As an excellent single-crystal material, mullite whiskers have good seismic resistance, high refractoriness, good thermal stability, low thermal expansion coefficient, low density, good mechanical strength, and high stability in harsh chemical environments. They can be used as reinforcements for excellent ceramic materials and can significantly improve their mechanical properties.

[0004] The preparation methods of mullite whiskers include: solid-phase method, molten salt method, sol-gel method, hydrothermal method, mineral decomposition method, oxide doping method, and in-situ synthesis method. The solid-phase method has a short process flow and simple operation, but it is difficult to control the growth process of whiskers. The molten salt method has a slow whisker growth rate, a long cycle, is easy to pollute the environment, and is difficult to recycle. The sol-gel method for preparing whiskers has a high cost, a complex process, and is not easy to control. The hydrothermal method has a slow whisker growth rate, a high cost, difficult to control the size, and complex post-treatment. The whiskers prepared by the mineral decomposition method and the oxide doping method have a high impurity content, seriously affecting the performance of the products. The in-situ synthesis method mixes materials and incorporates raw materials for generating whiskers. The formed phases in-situ generate whiskers during the sintering process, and the whiskers are evenly dispersed, solving the problem of difficult uniform dispersion of externally placed whiskers. And the in-situ synthesis method does not require pre-synthesizing whiskers, greatly simplifies the preparation process, and reduces the production cost.

[0005] Therefore, how to provide a preparation method of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramic has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramic to obtain cordierite porous ceramic with high porosity and high strength.

[0007] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a preparation method for in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics, comprising the following steps:

[0009] 1) Conduct primary ball milling and mixing on the mixture of magnesium source, aluminum source, and silicon source. After the mixing is completed, add a pore-forming agent and conduct secondary ball milling and mixing to obtain a mixed material;

[0010] 2) Press the mixed material into a shape to obtain a green body;

[0011] 3) Dry the green body and then conduct staged sintering to obtain in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics;

[0012] The staged sintering is to heat the dried green body from room temperature to a first temperature and hold for heat preservation; then heat it to a second temperature and hold for heat preservation;

[0013] The heating rate of the first temperature is 1 - 8 °C / min, the first temperature is 1200 - 1300 °C, and the heat preservation time is 0.5 - 6 h;

[0014] The heating rate of the second temperature is 1 - 6 °C / min, the second temperature is 1300 - 1450 °C, and the heat preservation time is 0.1 - 3 h.

[0015] Optionally, the magnesium source is magnesium oxide; the aluminum source is alumina; the silicon source is silica;

[0016] The particle sizes of the magnesium source, aluminum source, and silicon source are all ≤ 75 μm.

[0017] Optionally, the dosages of the magnesium source, aluminum source, and silicon source are in parts by weight, 10 - 15 parts of magnesium source, 30 - 45 parts of aluminum source, and 45 - 55 parts of silicon source.

[0018] Optionally, the pore-forming agent is an organic pore-forming agent or an inorganic pore-forming agent. The organic pore-forming agent includes starch, urea, or sawdust; the inorganic pore-forming agent includes ammonium carbonate, activated carbon, or ammonium chloride.

[0019] Optionally, the addition amount of the pore-forming agent is 1 - 40% of the mixture of magnesium source, aluminum source, and silicon source.

[0020] Optionally, the ball milling uses corundum grinding balls;

[0021] In the primary ball milling, the mass ratio of material to balls is 1:1 - 5, the rotation speed of the ball milling is 200 - 380 r / min, the ball milling is carried out by alternating forward / backward rotation, with forward / backward rotation alternating once every 5 - 45 minutes, and the ball milling time is 1 - 8 h;

[0022] In the secondary ball milling, the rotation speed of the ball milling is 380 - 450 r / min, and the ball milling is carried out by alternating forward and reverse rotations. The forward and reverse rotations alternate once every 5 - 45 minutes, and the ball milling time is 1 - 8 h.

[0023] Optionally, the pressure of the green compact is 15 - 40 MPa, and the time is 1 - 20 min.

[0024] Optionally, the drying temperature is 40 - 60 °C, and the time is 1 - 24 h.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a preparation method of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics. The method combines two-stage ball milling for mixing and segmented sintering to in-situ synthesize mullite whiskers. By adjusting the sintering process, the quantity, size, and distribution of the whiskers are controlled within a suitable range, and then mullite whisker self-reinforced cordierite porous ceramics with high porosity and high strength are prepared.

[0027] A large number of intertwined needle-like mullite phases are formed in the cordierite matrix prepared by the present invention. The diameter of the mullite whiskers is between 0.5 - 1 μm, the length is between 2 - 20 μm, and when the porosity of the porous ceramics is 57.16%, the compressive strength reaches 12.2 MPa. The introduction of the mullite whiskers successfully enhances the performance of the cordierite porous ceramics.

[0028] The present invention can use industrial-grade mixed powders of alumina, magnesia, and silica as raw materials. The raw materials have a wide source, the composition is easy to control, and the process is easy to operate. Description of the Drawings

[0029] Figure 1 It is the micrograph of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics in Example 1;

[0030] Figure 2 It is the micrograph of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics in Example 2;

[0031] Figure 3 It is the micrograph of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics in Example 3;

[0032] Figure 4 It is the micrograph of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics in Comparative Example 1;

[0033] Figure 5 It is the macrostructure diagram of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics in Comparative Example 2 and Comparative Example 3;

[0034] Figure 6 Microstructure diagram of mullite whisker in-situ synthesized self-reinforced cordierite porous ceramic for Comparative Example 3;

[0035] Figure 7 Microstructure diagram of mullite whisker in-situ synthesized self-reinforced cordierite porous ceramic for Comparative Example 4;

[0036] Figure 8 XRD patterns of mullite whisker in-situ synthesized self-reinforced cordierite porous ceramics for Examples 1 - 3 and Comparative Examples 1 - 4. Detailed Description of the Invention

[0037] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0038] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0040] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are only exemplary.

[0041] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0042] All raw materials used in the following examples of the present invention are obtained commercially.

[0043] The present invention provides a preparation method of in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics, comprising the following steps:

[0044] 1) Perform primary ball milling and mixing on the mixture of magnesium source, aluminum source, and silicon source. After the mixing is completed, add a pore-forming agent and perform secondary ball milling and mixing to obtain a mixed material;

[0045] 2) Press the mixed material into a green body;

[0046] 3) Dry the green body and then perform segmented sintering to obtain in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics;

[0047] The segmented sintering is to heat the dried green body from room temperature to a first temperature and keep it warm; then heat it to a second temperature and keep it warm;

[0048] The heating rate of the first temperature is 1-8 °C / min, preferably 2-7 °C / min, more preferably 3-6 °C / min, and even more preferably 4-5 °C / min. The first temperature is 1200-1300 °C, preferably 1210-1290 °C, more preferably 1230-1270 °C, and even more preferably 1250-1260 °C. The heat preservation time is 0.5-6 h, preferably 1-5 h, more preferably 2-4 h, and even more preferably 2.5-3 h;

[0049] The heating rate of the second temperature is 1-6 °C / min, preferably 2-5 °C / min, more preferably 2.5-4.5 °C / min, and even more preferably 3-4 °C / min. The second temperature is 1300-1450 °C, preferably 1320-1400 °C / min, more preferably 1340-1380 °C / min, and even more preferably 1350-1360 °C / min. The heat preservation time is 0.1-3 h, preferably 0.3-2 h, more preferably 0.4-1.5 h, and even more preferably 1-1.5 h.

[0050] In the present invention, the magnesium source is magnesium oxide; the aluminum source is aluminum oxide; the silicon source is silicon dioxide;

[0051] The particle sizes of the magnesium source, aluminum source, and silicon source are all ≤75 μm, preferably ≤70 μm, more preferably ≤60 μm, and even more preferably ≤55 μm.

[0052] In the present invention, the dosages of the magnesium source, aluminum source, and silicon source are in parts by weight. The magnesium source is 10-15 parts, preferably 11-14 parts, more preferably 12-13 parts, and most preferably 13 parts;

[0053] 30 to 45 parts of aluminum source, preferably 32 to 44 parts, more preferably 34 to 42 parts, even more preferably 36 to 40 parts, and most preferably 38 parts;

[0054] 45 to 55 parts of silicon source, preferably 46 to 54 parts, more preferably 47 to 52 parts, even more preferably 48 to 50 parts, and most preferably 49 parts.

[0055] In the present invention, the pore-forming agent is an organic pore-forming agent that burns during heating or an inorganic pore-forming agent that decomposes into gas phase at high temperature. The organic pore-forming agent includes starch, urea, sawdust, etc., preferably starch; the inorganic pore-forming agent includes ammonium carbonate, activated carbon, ammonium chloride, etc., preferably activated carbon.

[0056] In the present invention, the addition amount of the pore-forming agent is 1 to 40% of the mixture of magnesium source, aluminum source, and silicon source, preferably 5 to 35%, more preferably 10 to 30%, even more preferably 15 to 25%.

[0057] In the present invention, corundum grinding balls are used for ball milling;

[0058] In the first ball milling, the mass ratio of material to balls is 1:1 to 5, preferably 1:2 to 4, more preferably 1:3 to 3.5, and most preferably 1:2. The rotation speed of ball milling is 200 to 380 r / min, preferably 240 to 340 r / min, more preferably 260 to 320 r / min, even more preferably 280 to 300 r / min, and most preferably 350 r / min. The ball milling is carried out by alternating forward and reverse rotations, with forward and reverse rotations alternating once every 5 to 45 minutes, preferably 10 to 40 minutes, more preferably 15 to 30 minutes, even more preferably 20 to 25 minutes. The ball milling time is 1 to 8 h, preferably 2 to 7 h, more preferably 3 to 6.5 h, even more preferably 5 to 6 h, and most preferably 6 h;

[0059] In the second ball milling, the rotation speed of ball milling is 380 to 450 r / min, preferably 390 to 440 r / min, more preferably 400 to 430 r / min, even more preferably 410 to 420 r / min, and most preferably 400 r / min. The ball milling is carried out by alternating forward and reverse rotations, with forward and reverse rotations alternating once every 5 to 45 minutes, preferably 10 to 40 minutes, more preferably 15 to 30 minutes, even more preferably 20 to 25 minutes. The ball milling time is 1 to 8 h, preferably 2 to 7 h, more preferably 3 to 6 h, even more preferably 4 to 5 h, and most preferably 4 h.

[0060] In the present invention, the pressing pressure is 15-40 MPa, preferably 20-35 MPa, more preferably 25-32 MPa, and further preferably 28-30 MPa; the pressing time is 1-20 min, preferably 2-15 min, more preferably 4-10 min, and further preferably 5-6 min.

[0061] In the present invention, the drying temperature is 40-60°C, preferably 42-55°C, more preferably 45-52°C, and further preferably 48-50°C; the drying time is 1-24h, preferably 4-20h, more preferably 6-15h, and further preferably 8-10h.

[0062] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0063] Example 1

[0064] (1) Ingredients: Weigh 13 parts by weight of magnesium oxide, 38 parts by weight of aluminum oxide and 49 parts by weight of silicon dioxide, and weigh 20% of the total weight of magnesium oxide, aluminum oxide and silicon dioxide; and starch as a pore-forming agent.

[0065] (2) Mixing powder: industrial-grade alumina, magnesium oxide and silicon dioxide are ball-milled with a material-ball mass ratio of 1:2, the ball mill speed is 350 r / min, and the ball milling is performed by alternating forward / reverse rotation, the forward / reverse rotation is alternated every 25 minutes, the ball milling time is 6 hours, and an appropriate amount of deionized water or purified water is added and mixed evenly; then starch is added for ball milling, the ball mill speed is 400 r / min, and the ball milling is performed by alternating forward / reverse rotation, the forward / reverse rotation is alternated every 20 minutes, the ball milling time is 4 hours, and an appropriate amount of deionized water or purified water is added.

[0066] (3) Pressed blank: The dry pressing method is used for forming, the forming pressure is 30 MPa, and the sample diameter is The height was 12 mm, and a compact was obtained.

[0067] (4) Drying: Place the pressed green sheets in a drying oven at 50°C for 10 h.

[0068] (5) Sintering: The green body is placed in a sintering furnace for sintering. The sintering conditions are as follows: the temperature of the sintering furnace is increased to 1250°C at a rate of 5°C / min and kept at this temperature for 2.5 hours; then the temperature is increased to 1300°C at a rate of 3°C / min and kept at this temperature for 1.5 hours; and the green body is cooled to room temperature in the furnace to obtain a mullite whisker self-reinforced cordierite porous ceramic material.

[0069] Figure 1 The microstructure of the cordierite porous ceramics reinforced by in-situ synthesis of mullite whiskers in Example 1. Figure 1It can be seen that when the second temperature is 1300 °C, a large number of intertwined needle-like mullite phases are formed in the cordierite matrix, the number of whiskers increases significantly, the diameter of the mullite whiskers is less than 0.5 - 1 μm, and the length increases to 5 - 16 μm. Combining Figure 8 with the XRD results of

[0070] Example 2

[0071] The cordierite porous ceramic with mullite whisker self-reinforcement was prepared in the same manner as in Example 1, except that in step 5), the second temperature was different, and the second temperature was 1350 °C.

[0072] Figure 2 Fig. shows the microstructure of the cordierite porous ceramic with in-situ synthesized mullite whisker self-reinforcement in Example 2. From Figure 2 it can be seen that a large number of mullite whiskers with a diameter of 0.8 - 1 μm and a length of 6 - 20 μm are formed on the cordierite porous ceramic matrix. Comparing with Example 1, it can be known that the increase of the second temperature can promote the growth of mullite whiskers.

[0073] Example 3

[0074] The cordierite porous ceramic with mullite whisker self-reinforcement was prepared in the same manner as in Example 1, except that in step (5), the holding time at the second temperature was different, and the holding time was 1 h.

[0075] Figure 3 Fig. shows the microstructure of the cordierite porous ceramic with in-situ synthesized mullite whisker self-reinforcement in Example 3. From Figure 3 it can be seen that mullite whiskers with a diameter of 0.5 - 1 μm and a length of about 2 - 10 μm are formed in the pores of the cordierite matrix.

[0076] Comparative Example 1

[0077] The difference from Example 1 is only that the sintering conditions in step (5) are different. The sintering conditions are as follows: the sintering furnace is heated to 1250 °C at a rate of 5 °C / min and held for 4 h; then cooled to room temperature with the furnace to obtain the sample.

[0078] Figure 4 Fig. shows the microstructure of the cordierite porous ceramic with in-situ synthesized mullite whisker self-reinforcement in Comparative Example 1. From Figure 4 it can be seen that there are a small number of needle-like crystals inside the sample prepared at 1250 °C, which are intertwined and attached to the surface of the cordierite matrix. Combining Figure 8 with the XRD results of

[0079] Comparative Example 2

[0080] The difference from Example 1 is only that the ball milling process in step (2) is different. Industrial-grade alumina, magnesia, silica and pore-forming agent are ball milled with a material-to-ball mass ratio of 1:2, the rotational speed of the ball mill is 350 r / min, and the ball milling is carried out by alternating forward and reverse rotations, with a forward / reverse alternation every 25 minutes and a ball milling time of 10 h. An appropriate amount of deionized water or pure water is added and mixed evenly. The remaining steps are the same as those in Example 1 to obtain the sample.

[0081] Comparative Example 3

[0082] The difference from Example 1 lies in that the ball milling process in step (2) is different. Industrial-grade alumina, magnesia, silica and pore-forming agent are ball milled with a material-to-ball mass ratio of 1:2, the rotational speed of the ball mill is 350 r / min, and the ball milling is carried out by alternating forward and reverse rotations, with a forward / reverse alternation every 25 minutes and a ball milling time of 10 h. An appropriate amount of deionized water or pure water is added and mixed evenly; the sintering conditions in step (5) are different: the sintering furnace is heated to 1250 °C at a rate of 5 °C / min and held for 4 h to obtain the sample.

[0083] Figure 5 Macrographs of the in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics for Comparative Example 2 and Comparative Example 3. From Figure 5 it can be seen that the pore sizes of the mullite whisker self-reinforced cordierite porous ceramics prepared without segmented ball milling in Comparative Example 3 are different and the pore distribution is uneven. However, the pore sizes of Comparative Example 2 using segmented sintering are significantly reduced, about 1 / 3 to 1 / 5 of the pore sizes of Comparative Example 3.

[0084] Figure 6 Micrographs of the in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics for Comparative Example 3. From Figure 6 it can be seen that the pores of the cordierite porous ceramics without segmented ball milling and without segmented sintering are of different sizes, the pore diameters are about 5 - 400 μm, and the pore distribution is uneven, resulting in a decrease in the mechanical properties of the porous ceramics.

[0085] Comparative Example 4

[0086] The difference from Example 1 lies in that the sintering conditions in step (5) are different. The sintering furnace is heated to 1400 °C at a rate of 5 °C / min and held for 4 h to obtain the sample.

[0087] Figure 7 Micrographs of the in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics for Comparative Example 4. From Figure 7It can be seen that when the sintering temperature is 1400 °C and the sintering time is 4 h, the number of mullite whiskers increases and the length increases. The diameter of the whiskers is 1-6 μm, and the length increases to 10-40 μm. In Comparative Example 4, mullite whiskers with a relatively large aspect ratio were obtained. However, from the XRD pattern of Figure 8 it can be seen that the porous ceramic is mainly composed of mullite phase, and the cordierite phase is very few, and a porous ceramic with cordierite as the main phase cannot be prepared.

[0088] The porosity and compressive properties of the porous ceramics prepared in Examples 1-3 and Comparative Examples 1-4 were tested, and the test results are shown in Table 1.

[0089] Table 1 Performance test results of the porous ceramics prepared in Examples 1-3 and Comparative Examples 1-4

[0090] Porosity / % Compressive strength / MPa Comparative Example 1 40.47 5.1 Comparative Example 2 56.82 4.8 Comparative Example 3 60.48 4.2 Comparative Example 4 27.25 13.8 Example 1 45.41 9.5 Example 2 57.16 12.2 Example 3 42.32 6.3

[0091] As can be seen from Table 1, when the porosity of the cordierite porous ceramic self-reinforced by mullite whiskers prepared in the present invention is 57.16, the compressive strength reaches 12.2 MPa. The introduction of mullite whiskers successfully enhances the performance of the cordierite porous ceramic.

[0092] Figure 8 is the X-ray diffraction pattern of in-situ synthesized mullite whisker self-reinforced cordierite porous materials under different conditions. From Figure 8 it can be seen that the porous ceramic is mainly composed of a large amount of cordierite, a small amount of mullite and unreacted alumina. The ball milling process has no effect on the phase composition of the porous ceramic material. Moreover, as the temperature of the second stage increases and the holding time prolongs, the characteristic peaks of cordierite and unreacted alumina in the porous ceramic significantly decrease, and the characteristic peaks of mullite significantly increase. When the sintering temperature is 1400 °C and the sintering time is 4 h, the porous ceramic is mainly composed of mullite, containing a small amount of cordierite and alumina.

[0093] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics, characterized in that: The following steps are involved: 1) ball milling a mixture of a magnesium source, an aluminum source, and a silicon source, and after the mixing is completed, adding a pore-forming agent to perform a second ball milling to obtain a mixture; 2) pressing the mixed material into a shape to obtain a green body; 3) drying the green body and then sintering it in stages to obtain in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics; The staged sintering is to heat the dried green body from room temperature to a first temperature, keep it warm, and then heat it to a second temperature, keep it warm. The heating rate of the first temperature is 1-8°C / min, the first temperature is 1200-1250°C, and the insulation time is 0.5-6h; The heating rate of the second temperature is 1-6°C / min, the second temperature is 1300-1450°C, and the insulation time is 0.1-3h.

2. The method for preparing a porous cordierite ceramic by in-situ synthesis of mullite whiskers self-reinforced according to claim 1, characterized in that: The magnesium source is magnesium oxide; the aluminum source is aluminum oxide; and the silicon source is silicon dioxide; The particle sizes of the magnesium source, aluminum source and silicon source are all ≤75 μm.

3. The method for preparing a porous cordierite ceramic by in-situ synthesis of mullite whiskers self-reinforced according to claim 2, characterized in that: The usage of the magnesium source, aluminum source and silicon source is calculated in parts by weight: 10 to 15 parts of magnesium source, 30 to 45 parts of aluminum source and 45 to 55 parts of silicon source.

4. The method for preparing in-situ synthesized mullite whisker self-reinforced cordierite porous ceramic according to claim 1, characterized in that: The pore-forming agent is an organic pore-forming agent or an inorganic pore-forming agent. The organic pore-forming agent includes starch, urea or sawdust; the inorganic pore-forming agent includes ammonium carbonate, activated carbon or ammonium chloride.

5. The method for preparing in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics according to claim 4, characterized in that: The added amount of the pore-forming agent is 1-40% of the mixture of the magnesium source, the aluminum source and the silicon source.

6. The method for preparing in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics according to claim 1, characterized in that: The ball milling adopts corundum grinding balls; In the first ball milling, the mass ratio of the material and the ball is 1:1-5, the rotation speed of the ball mill is 200-380 r / min, the ball milling is performed by alternating forward / reverse rotation, the forward / reverse rotation is alternating once every 5-45 minutes, and the ball milling time is 1-8 hours; In the secondary ball milling, the rotation speed of the ball mill is 380-450 r / min, and the ball milling is performed by alternating forward / reverse rotation, with the forward / reverse rotation alternating once every 5-45 minutes, and the ball milling time is 1-8 hours.

7. The method for preparing in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics according to claim 1, characterized in that: The pressure of the compression molding is 15-40 MPa, and the time is 1-20 min.

8. The method for preparing in-situ synthesized mullite whisker self-reinforced cordierite porous ceramics according to claim 1, characterized in that: The drying temperature is 40-60° C. and the drying time is 1-24 hours.

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