A porous cordierite-mullite composite ceramic and a method for making the same

Abstract

The application discloses a kind of porous cordierite-mullite composite ceramics and preparation method thereof, and preparation raw materials of the composite ceramics include: amorphous aluminosilicate mineral 40-60 parts, talcum powder 5-25 parts, kaolin 5-15 parts, Longyan clay 15-25 parts by mass fraction.The porous cordierite-mullite composite ceramics of the application does not use pore-forming agent, foaming agent and other industrial inorganic chemicals, and the porous cordierite-mullite ceramic material obtained has through microporous structure, and the pore is micron level;The porous cordierite-mullite ceramic material has high thermal shock resistance and high mechanical strength;The eutectic phase of the porous cordierite-mullite composite ceramics contains mullite microcrystalline whisker generation.

Description

Technical Field

[0001] This invention relates to the field of multiphase ceramics preparation, specifically to a porous cordierite-mullite multiphase ceramic and its preparation method. Background Technology

[0002] Cordierite porous ceramics are widely used as catalyst supports, filtration and separation materials, refractory materials, and electronic device materials due to their low coefficient of thermal expansion, high porosity, good chemical stability, high temperature resistance, and large specific surface area. Generally, the higher the porosity of ceramics, the lower their mechanical properties. Therefore, the high porosity of cordierite porous ceramics leads to lower mechanical properties, thus limiting their applications. From the perspective of single material properties, cordierite alone... Mg2Al4Si5O18 Low coefficient of thermal expansion, strong thermal shock resistance, but relatively low mechanical strength; single mullite ( Al6Si2O13 Cordierite-mullite composite ceramics possess high melting point and high strength, but a slightly higher coefficient of thermal expansion. Therefore, while maintaining its three-in-one advantages of "porous structure + high-temperature resistance + chemical inertness," porous cordierite-mullite multiphase ceramic materials with mechanical strength have wider applications in high-temperature filtration, high-temperature catalyst carriers, aerospace thermal insulation materials, and solar thermal power generation heat absorption / storage materials. Furthermore, they can expand from traditional high-temperature industries to high-tech fields such as new energy, biology, electronic intelligent sensing, nuclear energy, and deep space exploration in extreme environments.

[0003] In existing technologies, the preparation of porous cordierite-mullite multiphase ceramics mainly employs solid-state sintering. Mineral raw materials or industrial chemical raw materials are mixed with pore-forming agents or foaming agents and then sintered in a solid-state manner. Pore-forming agents include starch, polymer microspheres, and carbon powder; during sintering, the pore-forming agents decompose or burn, leaving pores. Foaming agents include carbonates and organic foaming agents, which generate gas during sintering to form pores.

[0004] Commonly used solid-state sintering methods include clinker mixing sintering and in-situ reaction sintering. Clinker sintering involves high sintering temperatures, and the mixing of clinker is often done mechanically, resulting in weak interphase bonding. The process is complex, particle size classification is difficult to control, firing uniformity is poor, the forming method is limited, and the debinding sintering process is time-consuming. In-situ reaction sintering uses chemical reagents, leading to high raw material costs, making large-scale production difficult, and posing environmental problems due to organic emissions. Both clinker mixing sintering and in-situ reaction sintering involve pore-forming agents that contribute to environmental emissions during pore formation.

[0005] The existing patent CN200910180637.2 discloses a method for synthesizing porous cordierite-mullite composite material by using solid waste. Coal gangue, waste refractory material (waste magnesium carbon brick, waste slide plate brick) and wood chip pore forming agent are used as raw materials to obtain a synthesized sintered blank. The combustion of carbon-containing materials and wood chip pore forming agent produces CO2, causing secondary pollution, which is not conducive to environmental protection. The existing patent CN201120072917.4 discloses the preparation of porous cordierite-mullite ceramic. The addition of pore forming agent also produces CO2, causing secondary pollution, which is not conducive to environmental protection. Moreover, the glue removal time is long, energy consumption is high, and clean production is not conducive. The existing patent CN201210072947.4 discloses a porous cordierite-mullite composite ceramic material and a preparation method thereof. The sintering temperature is high (1320-1450°C), and the use of industrial raw materials increases the cost.

[0006] In summary, the existing technology has the following problems: the combustion of pore forming agent produces pores, causing CO2 and other gas emissions, resulting in secondary pollution; the use of organic binders in the process increases the glue removal time, increases energy consumption, and causes environmental pollution; the use of synthetic materials and industrial chemicals as raw materials increases the cost and energy consumption; and the high cost of raw material production, low mechanical strength of the prepared porous cordierite-mullite ceramic material, high sintering temperature, complex process, and low production efficiency. SUMMARY

[0007] To solve the problems of CO2 production caused by the use of pore forming agent, long glue removal time of organic binders, and environmental pollution in the preparation process of porous cordierite-mullite ceramic, the present application provides a porous cordierite-mullite composite ceramic and a preparation method thereof. The present application does not use existing pore forming agents and glue removers, and is low-temperature sintered, having high thermal shock resistance and high mechanical strength.

[0008] The first aspect of the present application provides a porous cordierite-mullite composite ceramic. The preparation raw materials of the composite ceramic include, in mass parts: amorphous aluminosilicate mineral 40-60 parts, talc powder 5-25 parts, kaolin 5-15 parts, and Longyan clay 15-25 parts.

[0009] Preferably, the preparation raw materials of the composite ceramic further include clay 5-20 parts.

[0010] Amorphous aluminosilicate mineral: mainly composed of silicon oxide, aluminum oxide and water, (Al2O3‧SiO2)m‧(H2O)n(containing 2-6wt% Fe2O3 )as the main raw material, the amorphous aluminosilicate mineral is a sponge-like substance formed by natural weathering of amorphous solid sol (gel) state, whose molecular structure is composed of aluminum, silicon and intermolecular water. The pore size of the sponge-like structure is nanometer micrometer level, and has high aluminum-silicon ratio. A through porous structure can be formed during in-situ solid phase reaction.

[0011] Talc: the main ingredient is hydrous magnesium silicate, the molecular formula is Mg3Si4O 10 (OH)2, as a source of magnesium to provide cordierite synthesis.

[0012] Kaolin: the phase of silicon oxide tetrahedral and aluminum oxide is stable in the crystal structure with a 1:1 layer structure; as an aluminum and silicon source for mullite formation, it participates in the solid solution solid phase reaction, and at the same time gives the composite ceramic good mechanical strength.

[0013] Longyan clay: Al2O3 (about 32%), SiO2 (about 52%), belongs to weathered residual type porcelain clay (kaolin) mineral class, has low porcelain firing temperature, generally in the range of 1100°C-1300°C, participates in the solid phase reaction, the function of Longyan clay is its balanced plasticity, sintering stability and mechanical strength of the ceramic after porcelain.

[0014] Pottery clay: Al2O3 (about 15%), SiO2 (more than about 70%), replacing Longyan clay with a certain proportion of pottery clay can further reduce the firing temperature, and the price is low, which can reduce the raw material cost of cordierite-mullite composite porous ceramic; in addition, adding pottery clay can improve the permeability of porous ceramic; but too much pottery clay will reduce the bending strength of porous cordierite-mullite composite ceramic.

[0015] Preferably, the preparation raw material of the composite ceramic further comprises a water reducing agent, and the present application does not limit the amount of water reducing agent, which can be increased or decreased according to the actual situation. In some specific embodiments of the present application, the water reducing agent is water glass, which is commonly used in ceramic process production, and its function is to reduce the amount of water added in the raw material and keep the raw material from being layered and hardened when placed.

[0016] In the present application, the preparation raw material of the composite ceramic further comprises water.

[0017] Preferably, the chemical composition of the amorphous aluminosilicate mineral includes: 35-40wt% SiO2, 34-38wt% Al2O3, 0.1-0.15wt% MgO, 2-6wt% Fe2O3, 0.4-0.6wt% CaO, 0.2-0.4wt% Na2O, 0.2-0.3wt% K2O, 0.3-0.4wt% TiO2.

[0018] Preferably, the chemical composition of the talc powder comprises: 60-70wt% SiO2, 0.5-0.7wt% Al2O3, 30-35wt% MgO, 0.03-0.05wt% Fe2O3, 0.5-0.6wt% CaO, 0.07-0.09wt% Na2O, 0.05-0.15wt% K2O, 0.01-0.03wt% TiO2.

[0019] Preferably, the chemical composition of the kaolin clay comprises: 50-60wt% SiO2, 40-45wt% Al2O3, 0.1-0.15wt% MgO, 0.2-0.4wt% Fe2O3, 0.05-0.1wt% CaO, 0.2-0.4wt% Na2O, 0.2-0.4wt% K2O, 0.4-0.6wt% TiO2. The small amount of iron content in the kaolin clay of the present application promotes the reaction.

[0020] Preferably, the chemical composition of the Longyan clay comprises: 50-55wt% SiO2, 30-35wt% Al2O3, 0.2-0.4wt% MgO, 0.2-0.3wt% Fe2O3, 0.1-0.2wt% CaO, 0.1-0.2wt% Na2O, 4-5wt% K2O, 0.03-0.05wt% TiO2.

[0021] Preferably, the chemical composition of the clay comprises: 65-75wt% SiO2, 10-20wt% Al2O3, 0.5-0.6wt% MgO, 5-6wt% Fe2O3, 0.1-0.15wt% CaO, 0.3-0.5wt% Na2O, 2-4wt% K2O, 0.7-0.9wt% TiO2.

[0022] The second aspect of the present application provides a preparation method of the porous cordierite-mullite composite ceramic, comprising the following steps: taking the preparation raw material, mixing, adding water and ball milling; shaping the ball-milled raw material to obtain a green body; placing the green body into a sintering furnace, sintering and cooling to obtain the porous cordierite-mullite composite ceramic.

[0023] Preferably, the sintering temperature is 1260℃-1380℃, the sintering time is 20-40min, and the heating rate is 2-5℃ / min.

[0024] Preferably, the step of cooling after sintering is: after high-temperature sintering, cooling to 1050-1150℃, holding for 40-60min, and then taking out and rapidly cooling to room temperature in air. The rapid cooling rate is ≥60℃ / min.

[0025] Preferably, the step of cooling after sintering is: after high-temperature sintering, naturally cooling to room temperature in the furnace, then re-heating to 1050-1150 DEG C, keeping for 40-60 min, and then taking out and rapidly cooling to room temperature in air. The rapid cooling treatment can promote the growth of the mullite whisker in the cordierite-mullite complex phase, improve the mechanical strength of the porous cordierite-mullite complex ceramic, and improve the strength of the pore structure.

[0026] In the porous cordierite-mullite complex ceramic prepared by the application, the cordierite phase is alpha-cordierite hexagonal chrysoberyl, the mullite phase is 3Al2O3·2SiO2 , and the two phases form an interlocking structure. The phase composition comprises 63-92 wt% of cordierite and 7-37 wt% of mullite; the complex phase crystal comprises mullite micro-whiskers.

[0027] The porous cordierite-mullite complex ceramic prepared by the application has a three-dimensional through-pore structure, mesopore-micron irregular-shaped pores, and water permeability, and the porosity is 18-30%.

[0028] The porous cordierite-mullite complex ceramic prepared by the application has a drainage method bulk density of 2.2-2.6g / cm3 , a room-temperature bending strength of 20-70 MPa, and a compressive strength of 1-140 MPa.

[0029] The porous cordierite-mullite complex ceramic prepared by the application has a strength retention rate of ≥90% after 3 times of thermal shock cycles at 1100 DEG C-room temperature, and the vessel does not crack.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] 1. Low-temperature sintering reduces energy consumption; the cordierite-mullite complex porous ceramic is formed by one-step solid-phase in-situ reaction; the sintering temperature is controlled at 1260-1300 DEG C, which is the best reaction sintering temperature, and is lower than the sintering temperature of the prior art;

[0032] 2. The amorphous aluminosilicate mineral (allochite) is used as the main raw material, the quasi-mineral has a high Al:Si ratio (Al2O3·SiO2·) m (H2O) n close to 2:1, which is higher than the aluminum-silicon ratio (1:2) of kaolin (Al2O3·2SiO2·2H2O); the design of the raw material does not need to add industrial alumina and other chemical solubilizers for preparing the cordierite-mullite complex ceramic material; the iron content of the raw material is about 2-6%, which can promote the synthesis of cordierite, and other inorganic reaction aids do not need to be added to promote the eutectic reaction of cordierite and mullite to form the complex ceramic;

[0033] 3. No pore-forming agent, foaming agent or other industrial inorganic chemicals are used, and the porous cordierite-mullite ceramic material obtained has a through-pore structure, and the pore is micron-sized;

[0034] 4. The porous cordierite-mullite ceramic material obtained has high thermal shock resistance and high mechanical strength; the eutectic phase of the porous cordierite-mullite composite ceramic contains mullite micro-whiskers;

[0035] 5. The porous cordierite-mullite composite ceramic can be formed in various and simple ways, such as semi-dry pressing or slip casting. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 X-ray diffraction phase analysis (XRD) of the composite ceramic prepared in Example 1;

[0037] Figure 2 Compression strength test of the composite ceramic prepared in Example 1;

[0038] Figure 3 SEM image of the composite ceramic prepared in Example 1;

[0039] Figure 4 Compression strength test of the composite ceramic prepared in Example 2;

[0040] Figure 5 SEM image of the composite ceramic prepared in Example 2;

[0041] Figure 6 Slip casting fired vessel of Example 3;

[0042] Figure 7 X-ray diffraction phase analysis (XRD) of the composite ceramic prepared in Example 4;

[0043] Figure 8 Compression strength test of the composite ceramic prepared in Example 4;

[0044] Figure 9 SEM image of the composite ceramic prepared in Example 4;

[0045] Figure 10 Compression strength test of the composite ceramic prepared in Example 5;

[0046] Figure 11 SEM image of the composite ceramic prepared in Example 5;

[0047] Figure 12 X-ray diffraction phase analysis (XRD) of the composite ceramic prepared in Example 6;

[0048] Figure 13 Compression strength test of the composite ceramic prepared in Example 6;

[0049] Figure 14 SEM image of the composite ceramic prepared in Example 6;

[0050] Figure 15 The compressive strength of the multiphase ceramic prepared in Example 7 was tested.

[0051] Figure 16 Electron micrograph of the multiphase ceramic prepared in Example 7;

[0052] Figure 17 X-ray diffraction (XRD) analysis of the multiphase ceramic prepared in Example 8.

[0053] Figure 18 The image shows an electron microscope image of the multiphase ceramic prepared in Example 8. Detailed Implementation

[0054] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0055] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0056] The chemical composition (wt%) of the raw materials in the following examples is shown in Table 1 below.

[0057] Table 1

[0058] ;

[0059] The amorphous aluminosilicate minerals used in the following examples are amorphous clay minerals composed of hydrated aluminosilicates with low crystallinity or amorphous formation. The raw material has a molecular structure consisting of 3.5-5 nanometer hollow layers of alumina and silica; the particle size distribution is approximately 2-130 micrometers, with 95% below 200 mesh, 60-70% below 20 micrometers, 20-35% between 20-40 micrometers, 5-6% between 40-75 micrometers, and 2% above 75 micrometers.

[0060] Example 1

[0061] (1) Ingredients: 45 parts of amorphous aluminosilicate minerals, 20 parts of talc powder, 10 parts of kaolin and 25 parts of dragon rock mud are mixed, 50 parts of water are added, and water glass water-reducing dispersant is added at 0.5% of the total weight of the materials.

[0062] (2) Ball milling: Place the mixed raw materials into a high-speed ball mill for ball milling (about 20 minutes); dry the milled material to remove water;

[0063] (3) Forming: semi-dry pressing forming;

[0064] (4) Drying: drying the green body in a drying oven (or in an infrared lamp oven);

[0065] (5) Sintering: the green body is put into a sintering furnace, and the sintering conditions are as follows: temperature is raised to 1000°C at a rate of 5°C / min, then raised to 1260°C at a rate of 2°C / min, kept for 0.5 hours, then reduced to 1100°C, kept for 50 minutes, and then the sintered sample is taken out and rapidly cooled in air; and a porous cordierite-mullite whisker eutectic composite ceramic is obtained.

[0066] XRD analysis shows that the content of cordierite in the cordierite-mullite composite ceramic is 65%, the content of mullite is 23%, and other phases are cristobalite, as shown in the XRD analysis. Figure 1 According to the mechanical property test, the bending strength is 64 MPa, the compressive strength is about 6-105 MPa, and the compressive test result shows non-brittle fracture. When the pressure is increased to 6 MPa, a small change in pressure occurs, and no visible cracks and breakage of the sample occur. When the pressure is continuously increased to 105 MPa, the sample remains intact, but visible large cracks occur. The compressive strength test is shown in Figure 2 The volume density measured by the drainage method is 2.55 g / cm 3 . Pore analysis: total porosity is 23% by mercury intrusion method (MIP) analysis and evaluation, and the structure is connected. The average pore size is about 5.1 microns, and the permeability is 25.3 mD (millidarcy), indicating that the sample has slightly larger pore volume and slightly better adsorption or storage capacity. Electron microscopy shows that the porous micro-morphology is irregular micrometer-sized pores, and the eutectic interface state is good. The size of the pores is about tens of microns (the edges of the pores are round), and the high-magnification photograph shows that there are mullite micro-whiskers. The whiskers are coated with amorphous phases or grown from amorphous glass phases. The electron micrograph is shown in Figure 3 .

[0067] Example 2

[0068] The same as in Example 1, after mixing, ball milling, semi-dry pressing forming, and drying, the sample green body is put into a sintering furnace, and the sintering conditions are as follows: temperature is raised to 1000°C at a rate of 5°C / min, then raised to 1260°C at a rate of 2°C / min, kept for 0.5 hours, and then reduced to room temperature. The sample is taken out, and the performance is evaluated. According to the mechanical property test, the bending strength is 59 MPa, and the compressive strength is about 17-59.2 MPa. The test result shows non-brittle fracture. When the pressure is increased to 17 MPa, the sample partially cracks. When the pressure is continuously increased to 59 MPa, the sample breaks into blocks. The compressive strength test is shown in Figure 4 . Electron microscopy shows a through-hole structure similar to that of Example 1. High-magnification electron microscopy also shows that the pore morphology is similar to that of the sample of Example 1. The high-magnification photograph shows only a small amount of whisker-like material. The electron micrograph is shown in Figure 5 .

[0069] Example 3

[0070] The raw material ratio of the above Example 1 was mixed with 45 parts of amorphous aluminosilicate mineral, 20 parts of talc, 10 parts of kaolin, and 25 parts of Longyan clay, 150 parts of water was added, 0.5% of water glass dispersing agent based on the total weight of the material was added, ball milling (about 20 minutes), and then the slurry was injected into a container and dried, and then solid phase reaction sintering was performed. The sintering conditions were the same as in Example 1. After sintering, the container was subjected to thermal shock resistance test at 1100°C- room temperature for 3 cycles, and no cracks were observed in the container sample. The injection-molded and sintered container was as shown in Figure 6 , which had porous water permeability.

[0071] Example 4

[0072] The raw materials were mixed with 45 parts of amorphous aluminosilicate mineral, 20 parts of talc, 10 parts of kaolin, 15 parts of Longyan clay, and 10 parts of clay, 50 parts of water was added, and 0.5% of water glass dispersing agent based on the total weight of the material was added.

[0073] After the above ingredients were mixed, the same as in Example 1, ball milling, semi-dry pressing, drying of the green body, and solid phase sintering reaction were performed to obtain the porous cordierite-mullite composite ceramic. XRD analysis showed that the cordierite was 84.1%, the mullite was 7.1%, and the other phase was tridymite 8.78%, as shown in Figure 7 . According to the mechanical property test, the bending strength was 46.7 MPa, the compressive strength was 10~121 MPa, and the test results showed that the sample did not show brittle fracture, and when the pressure was increased to 10 MPa, the pressure changed slightly, and no visible cracks were observed in the sample, and when the pressure was further increased to 121 MPa, the sample showed larger cracks. The compressive strength test is shown in Figure 8 . The volume density was measured by drainage method to be 2.55 g / cm 3 ; the porosity was 22.6% by mercury intrusion method (MIP) analysis and evaluation: the average pore size was 6.2 microns, and the permeability was 51 mD (millidarcy). Electron microscopy showed that the porous micro-morphology was micron-level irregular through holes, the composite eutectic interface state was good, the composite ceramic contained mullite whiskers, the whiskers were short, and the pores were about tens of microns in size. The electron micrograph is shown in Figure 9 .

[0074] Example 5

[0075] The same as example 4, after mixing, ball milling, semi-dry pressing, drying, the sample body was put into a sintering furnace, and the sintering conditions were as follows: heating to 1000℃ at a rate of 5℃ / min, then heating to 1260℃ at a rate of 2℃ / min, keeping for 0.5h, and then cooling to room temperature in the furnace. The sample was taken out, and the performance was evaluated. According to the mechanical property test, the bending strength was 39.8Mpa, and the compressive strength was 4~110Mpa. The test results showed that the sample was not brittle, when the pressure reached 4MPa, the pressure changed slightly, and no visible cracks appeared on the sample. When the pressure continued to increase to 110MPa, the sample was broken into blocks. The compressive strength test is shown in Figure 10 The electron microscope observation showed that the pore morphology was similar to that of example 4, but there were almost no mullite whiskers, and the electron micrograph is shown in Figure 11 .

[0076] Example 6

[0077] The ingredients were mixed: 45 parts of amorphous aluminosilicate mineral, 20 parts of talc, 10 parts of kaolin, 5 parts of Longyan clay, and 20 parts of pottery clay were mixed, 50 parts of water was added, and 0.5% of water glass water reducing dispersant was added based on the total weight of the materials.

[0078] After the above ingredients were completed, the same as example 1, the ball milling, semi-dry pressing, drying of the sample body, and solid phase sintering reaction were carried out, and the porous cordierite-mullite composite ceramic was obtained. XRD analysis showed that the cordierite was about 92%, the mullite was 7.8%, and the other phases were less than 1%. The XRD analysis is shown in Figure 12 . According to the mechanical property test, the bending strength was 53MPa, and the compressive strength was about 4~140MPa. The test results showed that the sample was not brittle, when the pressure reached 4MPa, the pressure changed slightly, and no visible cracks appeared on the sample. When the pressure continued to increase to 140MPa, the sample was broken into blocks. The compressive strength test is shown in Figure 13 . The volume density was 2.51g / cm 3 ; mercury intrusion method (MIP) analysis: porosity was about 19%. The average pore size was 4 microns, and the permeability was greater than 1000 mD (millidarcy); electron microscope observation: the micro-morphology of the pores was through-hole, the composite eutectic interface state was good, there were mullite micro-whiskers, and the size of the pores was about tens of microns. The electron micrograph is shown in Figure 14 .

[0079] Example 7

[0080] Similar to Example 6, after batching, mixing, ball milling, semi-dry pressing, and drying, the sample blank was placed in a sintering furnace. The sintering conditions were: heating to 1000°C at 5°C / min, then heating to 1260°C at 2°C / min, holding at that temperature for 0.5 hours, and then cooling to room temperature with the furnace. Samples were taken and their performance evaluated. According to the mechanical property tests, the flexural strength was 32 MPa, and the compressive strength was approximately 1.6~120.1 MPa, showing non-brittleness. The compressive strength test also showed non-brittleness; when the pressure was increased to 1.6 MPa, a slight pressure change occurred, and the sample did not crack or break. Further pressure was applied to 120 MPa, and the sample developed larger cracks and fragmented pieces. The compressive strength test results were as follows... Figure 15 As shown; electron microscopy reveals the morphology of the through-holes, and a small number of whiskers can be observed. The electron micrograph is attached. Figure 16 As shown.

[0081] Example 8

[0082] The same materials were prepared, mixed, ball-milled, and semi-dry-pressed as in Example 4. After drying, reaction sintering was carried out at 1300℃: the sintering conditions were as follows: heating to 1000℃ at 5℃ / min, then heating to 1300℃ at 2℃ / min, holding at that temperature for 0.5 hours, cooling to 1100℃, holding at that temperature for 50 minutes, and then rapidly cooling the sintered sample in air to obtain a porous cordierite-mullite whisker eutectic multiphase ceramic. XRD analysis showed 74% cordierite, 26% mullite, and no other phases. (XRD details are missing from the original text.) Figure 17 As shown. According to mechanical property tests, the flexural strength is 42 MPa; the bulk density measured by the displacement method is 2.42 g / cm³. 3 Mercury intrusion method (MIP) analysis was used for evaluation: Porosity: 30%. The average pore size was approximately 3 micrometers, smaller than that of Example 4; Permeability: 21 mD (millidarcy). Electron microscopy showed that after cordierite-mullite reaction sintering, the pore morphology was similar to that of Example 4, with no major changes. Electron micrographs are attached. Figure 18 As shown.

[0083] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A porous cordierite-mullite multiphase ceramic, characterized in that, The raw materials for preparing the multiphase ceramic, by weight, include: 40-60 parts of amorphous aluminosilicate minerals, 5-25 parts of talc, 5-15 parts of kaolin, and 15-25 parts of dragon rock mud; The chemical composition of the amorphous aluminosilicate mineral includes: 35-40wt% SiO2, 34-38wt% Al2O3, 0.1-0.15wt% MgO, 2-6wt% Fe2O3, 0.4-0.6wt% CaO, 0.2-0.4wt% Na2O, 0.2-0.3wt% K2O, and 0.3-0.4wt% TiO2; The chemical composition of the kaolin includes: 50-60wt% SiO2, 40-45wt% Al2O3, 0.1-0.15wt% MgO, 0.2-0.4wt% Fe2O3, 0.05-0.1wt% CaO, 0.2-0.4wt% Na2O, 0.2-0.4wt% K2O, and 0.4-0.6wt% TiO2; The porous cordierite-mullite composite ceramic phase contains mullite whiskers; The raw materials used in the preparation do not contain pore-forming agents or desiccant.

2. The porous cordierite-mullite multiphase ceramic according to claim 1, characterized in that, The raw materials for preparing the multiphase ceramics also include 5-20 parts of clay.

3. The porous cordierite-mullite multiphase ceramic according to claim 1 or 2, characterized in that, The chemical composition of the Longyan mud includes: 50-55wt% SiO2, 30-35wt% Al2O3, 0.2-0.4wt% MgO, 0.2-0.3wt% Fe2O3, 0.1-0.2wt% CaO, 0.1-0.2wt% Na2O, 4-5wt% K2O, and 0.03-0.05wt% TiO2.

4. The porous cordierite-mullite multiphase ceramic according to claim 2, characterized in that, The chemical composition of the clay includes: 65-75wt% SiO2, 10-20wt% Al2O3, 0.5-0.6wt% MgO, 5-6wt% Fe2O3, 0.1-0.15wt% CaO, 0.3-0.5wt% Na2O, 2-4wt% K2O, and 0.7-0.9wt% TiO2.

5. A method for preparing porous cordierite-mullite multiphase ceramics according to any one of claims 1-4, characterized in that, The process includes the following steps: taking raw materials, mixing them, adding water and ball milling them; shaping the ball-milled raw materials to obtain a green body; placing the green body in a sintering furnace, sintering it, and then cooling it to obtain the porous cordierite-mullite multiphase ceramic. The sintering temperature is 1260℃-1380℃, the sintering time is 20-40min, and the heating rate is 2-5℃ / min. The cooling step after sintering is as follows: after high-temperature sintering, the temperature is lowered to 1050-1150℃, held for 40-60 minutes, and then taken out and placed in the air to cool rapidly to room temperature.

Images