A method for preparing a cordierite composite

Abstract

The application discloses a preparation method of a cordierite composite material, and comprises the following steps: preparing a cordierite mixed raw material slurry; preparing cordierite raw material particles by spray drying the cordierite mixed raw material slurry; mixing the cordierite raw material particles, silicon carbide powder and a second pore-forming agent to prepare a composite matrix raw material mixed powder; performing cold isostatic pressing forming on the matrix raw material mixed powder through a mold to obtain a composite matrix blank; performing sectional temperature rising sintering on the composite matrix blank to obtain a composite matrix; and performing one-time impregnation on the composite matrix through a first impregnation liquid, a second impregnation liquid and a third impregnation liquid to obtain the cordierite composite material. The prepared cordierite composite material has increased strength and improved thermal shock resistance, and the thermal expansion coefficient is not obviously increased. The internal through hole rate is high, the internal catalyst is uniformly distributed, the catalytic effect is good, and the service life is long.

Description

Technical Field

[0001] This invention relates to the field of cordierite, and more particularly to a method for preparing cordierite composite materials. Background Technology

[0002] Cordierite is widely used in the preparation of high-performance honeycomb ceramic particle traps and catalyst supports due to its significant advantages such as high temperature resistance, corrosion resistance, good thermal shock stability, high strength, large heat storage capacity, good thermal conductivity, and low coefficient of thermal expansion. However, due to the low strength of cordierite, it is prone to cracking or pore collapse during use, which leads to a reduced service life. Therefore, how to invent a method for preparing cordierite composite materials that increases the strength and thermal shock resistance of the prepared cordierite composite materials without significantly increasing the coefficient of thermal expansion, achieves high internal porosity, uniform internal catalyst distribution, good catalytic effect, and long service life has become an urgent problem to be solved in this field. Summary of the Invention

[0003] To address the aforementioned technical issues, a method for preparing cordierite composite materials is provided. This method increases the strength and thermal shock resistance of the prepared cordierite composite material without significantly increasing the coefficient of thermal expansion. It also achieves high internal porosity, uniform catalyst distribution, good catalytic effect, and long service life.

[0004] The present invention provides a method for preparing cordierite composite materials, characterized by comprising the following steps: Prepare a cordierite mixed raw material slurry; the cordierite mixed raw material slurry includes clay, talc powder, alumina powder, and a first pore-forming agent; Cordierite raw material particles were prepared by spray drying of a slurry of mixed cordierite raw materials. A composite matrix raw material mixed powder is prepared by mixing cordierite raw material particles, silicon carbide powder, and a second pore-forming agent; The matrix raw material powder is cold isostatically pressed into shape using a mold to obtain a composite matrix preform; The composite matrix is ​​obtained by sintering the composite matrix preform in stages with increasing temperature. A first impregnation solution is prepared, and the composite matrix is ​​impregnated once with the first impregnation solution, followed by heating once to obtain a primary composite material; A second impregnation solution is prepared, and the primary composite material is impregnated with the second impregnation solution for a second time, followed by a second heating to obtain a secondary composite material; A third impregnation solution was prepared, and the secondary composite material was impregnated three times with the third impregnation solution, followed by three heating processes to obtain the cordierite composite material.

[0005] Compared with the prior art, the beneficial effects of this invention are as follows: the cordierite mixed raw material slurry includes clay, talc powder, alumina powder, and a first pore-forming agent; cordierite raw material particles are prepared by spray drying the cordierite mixed raw material slurry; this facilitates the realization of… Cordierite produced during sintering has a low coefficient of thermal expansion and a high porosity; By mixing cordierite raw material particles, silicon carbide powder, and a second pore-forming agent to prepare a composite matrix raw material mixed powder, it is beneficial to increase the strength of the prepared cordierite composite material and improve its thermal shock resistance. Furthermore, the silicon carbide inside the cordierite composite material has through pores that connect the cordierite to the inside of the cordierite, which is beneficial to achieve uniform distribution of the catalyst inside the cordierite composite material and to improve the thermal shock resistance of the cordierite composite material. A primary composite material is obtained by preparing a first impregnation solution and impregnating the composite matrix with the first impregnation solution once, followed by heating once; a secondary composite material is obtained by preparing a second impregnation solution and impregnating the primary composite material a second time, followed by heating a second time; this achieves the goal of uniformly impregnating the catalyst into the cordierite composite material, while simultaneously enabling the internal loading of a bimetallic catalyst and improving catalytic efficiency. By preparing a third impregnation solution and impregnating the secondary composite material three times with the third impregnation solution, followed by three heating processes, cordierite composite material is obtained. This method helps to avoid the problem of reduced catalyst activity caused by the high internal porosity of cordierite composite material, which easily absorbs moisture.

[0006] Furthermore, the preparation process of the cordierite mixed raw material slurry includes: Anhydrous ethanol was added to the ball mill, followed by clay, talc, and oxide. Aluminum powder and the first pore-forming agent are ball-milled for 12-24 hours. During the ball milling process, the cold source in the jacket of the ball milling equipment is cooled down to -20 to 5℃. The particle size of the solid particles after ball milling is 10-20μm.

[0007] The advantages of the previous step are that the ball milling time is 12-24 hours; during the ball milling process, the cold source in the jacket of the ball milling equipment is cooled down, and the temperature of the cold source is -20 to 5℃; this avoids the problem of reduced particle activity caused by excessively large particle size, which is not conducive to the subsequent sintering preparation of cordierite, and at the same time avoids the problem of reduced porosity of the prepared cordierite caused by excessively small particle size. Using a cold source temperature of -20 to 5℃ helps to avoid the problem of other elements crystallizing under the influence of potassium due to excessively high material temperature during the grinding process, thus avoiding the problem of reduced purity of the prepared cordierite.

[0008] Furthermore, the mass ratio of the clay, talc, alumina powder, and the first pore-forming agent is (40-50):(25-35):(15-20):(5-10).

[0009] The first pore-forming agent comprises graphite fibers and PMMA microspheres in a mass ratio of (1-3):(2-4); The graphite fiber aspect ratio is (10-20):1, and the length is 50-150μm; the PMMA microsphere particle size is 5-15μm.

[0010] The beneficial effect of the previous step is that, by using the first pore-forming agent, which includes graphite fibers and PMMA microspheres in a mass ratio of (1-3):(2-4), it is beneficial to achieve the directional growth of cordierite along the graphite fiber axis during the cordierite sintering process, thereby facilitating the preparation of α-type cordierite and thus facilitating the preparation of cordierite composite materials with a low coefficient of thermal expansion; and in the later stage of sintering, the graphite fibers volatilize, generating fibrous channels that penetrate the cordierite, thereby improving the overall connectivity between the inside and outside of the cordierite; PMMA microspheres are used to generate a certain number of through-pores along the radial direction of the fibrous channels, thereby improving the communication efficiency between the inside and outside of cordierite. This is beneficial for improving the catalytic efficiency of cordierite composite materials.

[0011] Furthermore, the particle size of the cordierite raw material is 30-100μm.

[0012] Furthermore, the mass ratio of the cordierite raw material particles, silicon carbide powder, and the second pore-forming agent is (60-70):(25-30):(5-10); The second pore-forming agent comprises starch fiber, wherein the starch fiber has an aspect ratio of (15-25):1 and a length of 200-400 μm.

[0013] The beneficial effect of the previous step is that the mass ratio of the cordierite raw material particles, silicon carbide powder, and the second pore-forming agent is (60-70):(25-30):(5-10), which is conducive to the formation of several fibrous channels between cordierite and silicon carbide, thereby facilitating the high efficiency of internal and external communication of cordierite.

[0014] Furthermore, during the preparation of the composite matrix preform, the cold isostatic pressing pressure is 50-100 MPa.

[0015] Furthermore, the staged heating and sintering of the composite matrix preform includes the following steps: The composite matrix preform was heated from room temperature to 60-100℃ in an argon atmosphere at a heating rate of 8-9℃ / min. The temperature was increased from 60-100℃ to 200-300℃ in an argon atmosphere at a rate of 3-4℃ / min. The temperature was increased from 200-300℃ to 600-900℃ in an argon atmosphere at a rate of 1-2℃ / min. The temperature was increased from 600-900℃ to 1100-1200℃ in an argon atmosphere at a rate of 3-5℃ / min, and then held at 1100-1200℃ for 2-2.2 h. The temperature was increased from 1100℃-1200℃ to 1350℃-1400℃ in air at a rate of 4-5℃ / min, and then held at 1350℃-1400℃ for 2-2.2 h.

[0016] The beneficial effect of the previous step is that by heating the composite matrix preform from room temperature to 60-100℃ in an argon atmosphere at a heating rate of 8-9℃ / min, small molecule volatiles are rapidly volatilized, and it is beneficial to form through pores during the volatilization process; through the argon atmosphere, the carbon fiber will not be oxidized in an oxygen-free environment. By heating from 60-100℃ to 200-300℃ in an argon atmosphere at a rate of 3-4℃ / min, larger molecular weight organic compounds are slowly decomposed; and carbon fibers are not oxidized in an oxygen-free environment under an argon atmosphere. The temperature is increased from 200-300℃ to 600-900℃ in an argon atmosphere at a rate of 1-2℃ / min; this allows for the slow volatilization of larger molecular weight organic materials (including starch fibers) to form through-pores; and the carbon fibers are not oxidized in an oxygen-free environment due to the argon atmosphere. The temperature was increased from 600-900℃ to 1100-1200℃ in an argon atmosphere at a rate of 3-5℃ / min, and then held at 1100-1200℃ for 2-2.2 h; this process was achieved at this temperature. The reaction yields cordierite, and the carbon fibers will not be oxidized in an oxygen-free environment, which is conducive to the formation of cordierite along the carbon fibers and helps to avoid a significant increase in the thermal expansion coefficient of the cordierite composite material. By heating from 1100℃-1200℃ to 1350℃-1400℃ in air at a rate of 4-5℃ / min and holding at 1350℃-1400℃ for 2-2.2 h, it is beneficial for the graphite fibers to be oxidized and volatilized in an aerobic environment after the cordierite is basically formed at this stage, thus forming fibrous channels inside the cordierite.

[0017] Furthermore, the process of preparing the first impregnation solution includes preparing a 0.03-0.05% (by mass) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate, with water as the solvent; Add citric acid or ascorbic acid to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate; Then, manganese salt is added and stirred to obtain the first impregnation solution; the manganese salt includes one of manganese nitrate, manganese acetate, and manganese sulfate. The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate, manganese salt, citric acid, or ascorbic acid is (1-2):(5-10):(0.5-1). The process of impregnating the composite matrix with the first impregnation solution includes: The composite matrix was placed in the first impregnation and impregnated at room temperature for 12-24 hours. The heating process includes heating the impregnated composite matrix in a N2 or Ar atmosphere at 100-120℃ for 2-5 hours; Then heat at 350-450℃ for 3-4 hours.

[0018] The beneficial effects of the previous step are that the bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate solution helps to achieve uniform dispersion inside the first impregnation solution, and at the same time helps to impregnate the manganese salt into the through-pores inside and outside the cordierite, and to disperse it evenly inside; the use of citric acid or ascorbic acid helps to form oxygen vacancies inside the cordierite composite material at the first heating temperature of 350-450℃, which helps to improve catalytic efficiency. The process involves heating the impregnated composite matrix at 350-450℃ for 3-4 hours under a N2 or Ar atmosphere, thereby promoting the decomposition of manganese nitrate to generate MnO in a low-oxygen environment. x A large number of oxygen vacancies are generated (in Mn³⁺ / Mn 4 (⁺Defect pairs exist), these oxygen vacancies, as active centers, can significantly enhance the adsorption and activation capacity of NO and NH3; at the same time, the fibrous channels provide abundant exposed crystal faces, which is conducive to the stable existence of oxygen vacancies; and the bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate and citric acid or ascorbic acid volatilize when heated, avoiding the problem of significant reduction in porosity due to impregnation.

[0019] Furthermore, the process of preparing the second impregnation solution includes preparing a 0.03-0.05% (by mass) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate, with water as the solvent; Add citric acid or ascorbic acid to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate; Then, copper salts are added and stirred to obtain a second impregnation solution; the copper salts include one of copper nitrate, copper acetate, and copper sulfate. The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate, copper salt, citric acid, or ascorbic acid is (1-2):(5-10):(0.5-1). The process of secondary impregnation of the composite matrix with a second impregnation solution includes: The composite matrix was placed in the second impregnation and impregnated at room temperature for 12-24 hours. The secondary heating process includes: heating the impregnated composite matrix in an air atmosphere. Heat at 100-120℃ for 2-5 hours; Then heat at 400-500℃ for 2-3 hours.

[0020] The beneficial effect of the previous step is that Cu²⁺ will preferentially occupy the defect sites on the surface of Mn oxide or form Mn-Cu composite precursors; Heating in an air atmosphere transforms Cu²⁺ into highly dispersed CuO nanoparticles, which then react with MnO. x A Mn-Cu bimetallic oxide interface is formed; at this interface, additional oxygen vacancies are generated due to lattice mismatch, forming “Mn-Ov-Cu” synergistic active sites, which greatly improves the low-temperature denitrification efficiency; and the NO conversion rate of cordierite composite material is >90% in the range of 150-250℃.

[0021] Furthermore, the process of preparing the third impregnation solution includes preparing a 0.01-0.02% (by mass) solution of bispalmitoyl carboxyethyl-hydroxyethyl methyl ammonium sulfate, with water as the solvent; Citric acid or ascorbic acid is added to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate to obtain a third impregnation solution; The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethyl methyl ammonium sulfate to citric acid or ascorbic acid is (1-2):(0.5-1). The process of impregnating the composite matrix three times with a third impregnation solution includes: The composite matrix is ​​placed in the third impregnation, and each time it is impregnated at room temperature for 2-4 hours, then removed and left to stand for 0.5-1 hour; the above impregnation steps are repeated 3-4 times. The three heating processes include: The impregnated composite matrix is ​​heated at 100-120℃ for 2-5 hours.

[0022] The beneficial effect of the previous step is that the dipalmitoyl carboxyethyl-hydroxyethyl methyl ammonium sulfate molecule is adsorbed onto the surface of the catalyst and support through electrostatic and hydrogen bonding, forming an ultrathin organic protective film of <5 nm. The organic protective film can physically isolate poisons such as SO2 and water vapor in the environment and delay the loss of active components of the catalyst. The polar head groups (quaternary ammonium salt, ester group) of dipalmitoyl carboxyethyl-hydroxyethyl methyl ammonium sulfate are conducive to enhancing the "enrichment" ability of acidic NOx and basic NH3, and work in synergy with the oxygen vacancy below to achieve the integration of "capture-activation-reaction". This is beneficial for improving the catalytic performance of cordierite composite materials. Detailed implementation method: To better understand the technical solution of the present invention, the present invention will be further described below with reference to specific embodiments.

[0023] Example 1: This embodiment provides a method for preparing cordierite composite materials, including the following steps: Prepare a cordierite mixed raw material slurry; the cordierite mixed raw material slurry includes clay, talc powder, alumina powder, and a first pore-forming agent; The preparation process of the cordierite mixed raw material slurry includes: Anhydrous ethanol was added to the ball mill, followed by clay, talc, and oxide. Aluminum powder and the first pore-forming agent were ball-milled for 18 hours. During the ball-milling process, the cold source in the jacket of the ball mill was cooled to -8°C. The particle size of the solid particles after ball milling was 15μm. The mass ratio of the clay, talc powder, alumina powder, and the first pore-forming agent is 45:30:18:8.

[0024] The first pore-forming agent comprises graphite fibers and PMMA microspheres in a mass ratio of 2:3; The graphite fiber aspect ratio is (10-20):1, and the length is 50-150μm; the PMMA microsphere particle size is 5-15μm.

[0025] Cordierite raw material particles are prepared by spray drying of a mixed raw material slurry of cordierite; the particle size of the cordierite raw material particles is 30-100μm.

[0026] A composite matrix raw material mixed powder is prepared by mixing cordierite raw material particles, silicon carbide powder, and a second pore-forming agent; The mass ratio of the cordierite raw material particles, silicon carbide powder, and the second pore-forming agent is 65:27:7; The second pore-forming agent comprises starch fiber, wherein the starch fiber has an aspect ratio of (15-25):1 and a length of 200-400 μm.

[0027] The matrix raw material powder is cold isostatically pressed into shape using a mold to obtain a composite matrix preform; During the preparation of the composite matrix preform, the cold isostatic pressing pressure is 75 MPa.

[0028] The composite matrix is ​​obtained by sintering the composite matrix preform in stages with increasing temperature. The composite matrix preform undergoes segmented heating and sintering, which includes the following steps: The composite matrix preform was heated from room temperature to 80°C in an argon atmosphere at a heating rate of 8.5°C / min. The temperature was increased from 80℃ to 250℃ in an argon atmosphere at a rate of 3.5℃ / min. The temperature was increased from 250℃ to 750℃ in an argon atmosphere at a rate of 1.5℃ / min. The temperature was increased from 750℃ to 1150℃ in an argon atmosphere at a rate of 4℃ / min, and then held at 1150℃ for 2.1 h. The temperature was increased from 1150℃ to 1380℃ in air at a rate of 4.5℃ / min, and then held at 1380℃ for 2.1 hours.

[0029] A first impregnation solution is prepared, and the composite matrix is ​​impregnated once with the first impregnation solution, followed by heating once to obtain a primary composite material; The process of preparing the first impregnation solution includes preparing a 0.04% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate, with water as the solvent; Add citric acid or ascorbic acid to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate; Then, manganese salts are added and stirred to obtain the first impregnation solution; the manganese salts include manganese nitrate. The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate, manganese salt, citric acid, or ascorbic acid is 1.5:7:0.7. The process of impregnating the composite matrix with the first impregnation solution includes: The composite matrix was placed in the first impregnation and impregnated at room temperature for 18 hours. The heating process includes: heating the impregnated composite matrix in an Ar atmosphere at 110°C for 3.5 hours; Then heat at 400℃ for 3.5 h.

[0030] A second impregnation solution is prepared, and the primary composite material is impregnated with the second impregnation solution for a second time, followed by a second heating to obtain a secondary composite material; The process of preparing the second impregnation solution includes preparing a 0.04% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate, with water as the solvent; Add citric acid or ascorbic acid to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate; Then copper salts are added and stirred to obtain a second impregnation solution; the copper salts include copper nitrate; The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate, copper salt, citric acid, or ascorbic acid is 1.5:7:0.7; The process of secondary impregnation of the composite matrix with a second impregnation solution includes: The composite matrix was placed in the second impregnation and impregnated at room temperature for 18 hours. The secondary heating process includes: heating the impregnated composite matrix in an air atmosphere. Heat at 110℃ for 3.5 hours; Then heat at 450℃ for 2.5 h.

[0031] A third impregnation solution was prepared, and the secondary composite material was impregnated three times with the third impregnation solution, followed by three heating processes to obtain the cordierite composite material.

[0032] The process of preparing the third impregnation solution includes preparing a 0.015% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate, with water as the solvent; Citric acid or ascorbic acid is added to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate to obtain a third impregnation solution; The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate to citric acid or ascorbic acid is 1.5:0.7; The process of impregnating the composite matrix three times with a third impregnation solution includes: The composite matrix was placed in the third impregnation, and each time it was impregnated at room temperature for 3 hours and then removed and allowed to stand for 0.7 hours; the above impregnation steps were repeated 3 times. The three heating processes include: The impregnated composite matrix was heated at 110°C for 3.5 hours.

[0033] Example 2: The content that is the same as in Example 1 will not be repeated here; the differences between this example and Example 1 are as follows: This example provides a method for preparing cordierite composite materials, and also includes: During the preparation of the cordierite mixed raw material slurry, the ball milling time was 22 hours; the cold source temperature was -15℃. The mass ratio of the clay, talc, alumina powder, and the first pore-forming agent is 49:34:18:9.

[0034] The first pore-forming agent comprises graphite fibers and PMMA microspheres in a mass ratio of 2.8:2.6.

[0035] The mass ratio of the cordierite raw material particles, silicon carbide powder, and the second pore-forming agent is 68:28:9. During the preparation of the composite matrix preform, the cold isostatic pressing pressure is 90 MPa.

[0036] The composite matrix preform was heated from room temperature to 90°C in an argon atmosphere at a heating rate of 8.9°C / min. The temperature was increased from 90℃ to 290℃ in an argon atmosphere at a rate of 3.9℃ / min. The temperature was increased from 290℃ to 880℃ in an argon atmosphere at a rate of 1.8℃ / min. The temperature was increased from 880℃ to 1190℃ in an argon atmosphere at a rate of 4.8℃ / min, and then held at 1190℃ for 2.02h. The temperature was increased from 1190℃ to 1390℃ in air at a rate of 4.9℃ / min, and then held at 1390℃ for 2.02 hours.

[0037] The process of preparing the first impregnation solution includes preparing a 0.048% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate. The manganese salt includes manganese acetate; The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethyl methyl ammonium sulfate, manganese salt, citric acid, or ascorbic acid is 1.8:9.5:0.95; The composite matrix was placed in the first impregnation and impregnated at room temperature for 23 hours. The heating process includes: heating the impregnated composite matrix in an Ar atmosphere at 118°C for 3 hours; and then heating it at 430°C for 3.2 hours.

[0038] The process of preparing the second impregnation solution includes preparing a 0.048% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate. The copper salt includes one of copper nitrate, copper acetate, and copper sulfate; The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate, copper salt, citric acid, or ascorbic acid is 1.8:9:0.9; The composite matrix was placed in the second impregnation and impregnated at room temperature for 23 hours. The secondary heating process includes: heating the impregnated composite matrix in an air atmosphere. The sample was heated at 118°C for 2.5 hours, and then at 430°C for 2.2 hours.

[0039] The process of preparing the third impregnation solution includes preparing a 0.08% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate. The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate to citric acid or ascorbic acid is 1.8:0.8; The composite matrix was placed in the third impregnation, and each time it was impregnated at room temperature for 3.8 hours and then removed and allowed to stand for 0.9 hours; the above impregnation steps were repeated 3-4 times. The three heating processes include heating the impregnated composite matrix at 118°C for 2.5 hours.

[0040] Example 3: The content that is the same as in Example 1 will not be repeated here; the differences between this example and Example 1 are as follows: This example provides a method for preparing cordierite composite materials, and also includes: During the preparation of the cordierite mixed raw material slurry, the ball milling time was 13 hours; the cold source temperature was -16℃. The mass ratio of the clay, talc, alumina powder, and the first pore-forming agent is 41:26:16:6.

[0041] The first pore-forming agent comprises graphite fibers and PMMA microspheres in a mass ratio of 1.2:2.3; The mass ratio of the cordierite raw material particles, silicon carbide powder, and the second pore-forming agent is 62:26:7; During the preparation of the composite matrix preform, the cold isostatic pressing pressure is 60 MPa.

[0042] The composite matrix preform was heated from room temperature to 70°C in an argon atmosphere at a heating rate of 8.2°C / min. The temperature was increased from 70℃ to 220℃ in an argon atmosphere at a rate of 3.3℃ / min. The temperature was increased from 220℃ to 700℃ in an argon atmosphere at a rate of 1.2℃ / min. The temperature was increased from 700℃ to 1120℃ in an argon atmosphere at a rate of 3.3℃ / min, and then held at 1100℃-1200℃ for 2-2.2 h. The temperature was increased from 1120℃ to 1360℃ in air at a rate of 4.1℃ / min, and then held at 13560℃ for 2.18 hours.

[0043] The process of preparing the first impregnation solution includes preparing a 0.032% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate. The manganese salt includes manganese nitrate sulfate; The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate, manganese salt, citric acid, or ascorbic acid is 1.2:5.5:0.6; The composite matrix was placed in the first impregnation and impregnated at room temperature for 13 minutes. The heating process includes: heating the impregnated composite matrix in a N2 atmosphere at 108°C for 4.6 hours; and then heating it at 360°C for 3.8 hours.

[0044] The process of preparing the second impregnation solution includes preparing a 0.032% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate. The copper salt includes copper sulfate; The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethyl methyl ammonium sulfate, copper salt, citric acid, or ascorbic acid is 1.2:5.5:0.6; The composite matrix was placed in the second impregnation and impregnated at room temperature for 13 hours. The secondary heating process includes: heating the impregnated composite matrix in an air atmosphere. The sample was heated at 106°C for 4.6 hours, and then at 410°C for 2.8 hours.

[0045] The process of preparing the third impregnation solution includes preparing a 0.012% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate. The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethyl methyl ammonium sulfate to citric acid or ascorbic acid is 1.2:0.58; The composite matrix was placed in the third impregnation, and each time it was impregnated at room temperature for 2.5 hours and then removed and allowed to stand for 0.6 hours; the above impregnation steps were repeated 3-4 times. The three heating processes include heating the impregnated composite matrix at 105°C for 2.5 hours.

[0046] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for preparing a cordierite composite material, characterized in that, Including the following step: Prepare a cordierite mixed raw material slurry; the cordierite mixed raw material slurry includes clay, talc powder, alumina powder, and a first pore-forming agent; Cordierite raw material particles were prepared by spray drying of a slurry of mixed cordierite raw materials. A composite matrix raw material mixed powder is prepared by mixing cordierite raw material particles, silicon carbide powder, and a second pore-forming agent; The matrix raw material powder is cold isostatically pressed into shape using a mold to obtain a composite matrix preform; The composite matrix is ​​obtained by sintering the composite matrix preform in stages with increasing temperature. A first impregnation solution is prepared, and the composite matrix is ​​impregnated once with the first impregnation solution, followed by heating once to obtain a primary composite material; A second impregnation solution is prepared, and the primary composite material is impregnated with the second impregnation solution for a second time, followed by a second heating to obtain a secondary composite material; A third impregnation solution was prepared, and the secondary composite material was impregnated three times with the third impregnation solution, followed by three heating processes to obtain the cordierite composite material.

2. The method for preparing cordierite composite material according to claim 1, wherein its features are as follows: The characteristic is that the preparation process of the cordierite mixed raw material slurry includes: Anhydrous ethanol was added to the ball mill, followed by clay, talc, and oxide. Aluminum powder and the first pore-forming agent are ball-milled for 12-24 hours. During the ball milling process, the cold source in the jacket of the ball milling equipment is cooled down to -20 to 5℃. The particle size of the solid particles after ball milling is 10-20μm.

3. The method for preparing cordierite composite material according to claim 1, characterized in that, The mass ratio of the clay, talc powder, alumina powder, and the first pore-forming agent is (40-50):(25-35):(15-20):(5-10); The first pore-forming agent comprises graphite fibers and PMMA microspheres in a mass ratio of (1-3):(2-4); The graphite fiber aspect ratio is (10-20):1, and the length is 50-150μm; the PMMA microsphere particle size is 5-15μm.

4. The method for preparing cordierite composite material according to claim 1, characterized in that, The particle size of the cordierite raw material is 30-100μm.

5. The method for preparing cordierite composite material according to claim 1, characterized in that, The mass ratio of the cordierite raw material particles, silicon carbide powder, and the second pore-forming agent is (60-70):(25-30):(5-10); The second pore-forming agent comprises starch fiber, wherein the starch fiber has an aspect ratio of (15-25):1 and a length of 200-400 μm.

6. The method for preparing cordierite composite material according to claim 1, characterized in that, During the preparation of the composite matrix preform, the cold isostatic pressing pressure is 50-100 MPa.

7. The method for preparing cordierite composite material according to claim 1, characterized in that, The composite matrix preform undergoes segmented heating and sintering, which includes the following steps: The composite matrix preform was heated from room temperature to 60-100℃ in an argon atmosphere at a heating rate of 8-9℃ / min. The temperature was increased from 60-100℃ to 200-300℃ in an argon atmosphere at a rate of 3-4℃ / min. The temperature was increased from 200-300℃ to 600-900℃ in an argon atmosphere at a rate of 1-2℃ / min. The temperature was increased from 600-900℃ to 1100-1200℃ in an argon atmosphere at a rate of 3-5℃ / min, and then held at 1100-1200℃ for 2-2.2 h. The temperature was increased from 1100℃-1200℃ to 1350℃-1400℃ in air at a rate of 4-5℃ / min, and then held at 1350℃-1400℃ for 2-2.2 h.

8. The method for preparing cordierite composite material according to claim 1, characterized in that, The process of preparing the first impregnation solution includes preparing a 0.03-0.05% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate, with water as the solvent; Add citric acid or ascorbic acid to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate; Then, manganese salt is added and stirred to obtain the first impregnation solution; the manganese salt includes one of manganese nitrate, manganese acetate, and manganese sulfate. The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate, manganese salt, citric acid, or ascorbic acid is (1-2):(5-10):(0.5-1). The process of impregnating the composite matrix with the first impregnation solution includes: The composite matrix was placed in the first impregnation and impregnated at room temperature for 12-24 hours. One heating process includes: heating the impregnated composite matrix under a N2 or Ar atmosphere. Heat at 100-120℃ for 2-5 hours; Then heat at 350-450℃ for 3-4 hours.

9. The method for preparing cordierite composite material according to claim 1, characterized in that, The process of preparing the second impregnation solution includes preparing a 0.03-0.05% (by mass) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate, with water as the solvent; Add citric acid or ascorbic acid to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate; Then, copper salts are added and stirred to obtain a second impregnation solution; the copper salts include one of copper nitrate, copper acetate, and copper sulfate. The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethylmethyl ammonium sulfate, copper salt, citric acid, or ascorbic acid is (1-2):(5-10):(0.5-1). The process of secondary impregnation of the composite matrix with a second impregnation solution includes: The composite matrix was placed in the second impregnation and impregnated at room temperature for 12-24 hours. The secondary heating process includes: heating the impregnated composite matrix in an air atmosphere. Heat at 100-120℃ for 2-5 hours; Then heat at 400-500℃ for 2-3 hours.

10. The method for preparing cordierite composite material according to claim 1, characterized in that, The preparation of the third impregnation solution includes preparing a 0.01-0.02% (w / w) solution of bispalmitoylcarboxyethyl-hydroxyethylmethylammonium sulfate, using water as the solvent; Citric acid or ascorbic acid is added to a solution of bispalmitocarboxyethyl-hydroxyethylmethylammonium sulfate to obtain a third impregnation solution; The mass ratio of the dipalmitoyl carboxyethyl-hydroxyethyl methyl ammonium sulfate to citric acid or ascorbic acid is (1-2):(0.5-1). The process of impregnating the composite matrix three times with a third impregnation solution includes: The composite matrix is ​​placed in the third impregnation, and each time it is impregnated at room temperature for 2-4 hours, then removed and left to stand for 0.5-1 hour; the above impregnation steps are repeated 3-4 times. The three heating processes include: The impregnated composite matrix is ​​heated at 100-120℃ for 2-5 hours.