Low-temperature sintered self-reinforced mullite whisker porous ceramic and preparation method thereof

Abstract

The invention relates to a low-temperature sintered self-reinforced mullite whisker porous ceramic and a preparation method thereof. According to the preparation technology disclosed by the invention, the sintering temperature is successfully reduced while the toughening performance of the material is remarkably improved, which has an extremely important influence on reduction of the production cost and optimization of the material performance. The porous ceramic with an in-situ mullite whisker skeleton is prepared by combining an in-situ whisker generation method, a pore-forming agent adding method and a sintering aid method. The optimal synthesis process of the mullite ceramic is obtained by accurately regulating and controlling the raw material ratio, the sintering temperature and the pore-forming agent type. In addition, growth of mullite crystal nucleuses is promoted through the synergistic effect of the sintering aid and the whisker catalyst, and low-temperature sintering of the mullite ceramic is achieved. The invention aims to explore and realize an optimization method for low-temperature sintering, toughening and strengthening, so as to promote the development and application of the porous mullite ceramic in a plurality of application fields such as sound absorption, heat preservation, filtration and catalyst carriers.

Description

Technical Field

[0001] The present application belongs to the field of ceramics, and in particular relates to a low-temperature sintered self-reinforced mullite whisker porous ceramic and a preparation method thereof. Background Art

[0002] Mullite is Al 2 O 3 -SiO 2 The only crystalline phase in the binary system that is stable at high temperature and normal pressure. Mullite has the advantages of low thermal expansion coefficient, low thermal conductivity, excellent creep resistance, good thermal shock resistance, and high stability under extreme chemical conditions. Therefore, due to its precisely controllable porous structure, high porosity, light weight, high temperature resistance, corrosion resistance and low thermal conductivity, it is of great significance in many applications such as sound absorption, heat insulation, filtration and catalyst carrier. The traditional synthesis method of mullite mainly relies on high-temperature solid-phase sintering, and its sintering temperature is as high as 1500 °C. The mullite synthesized by this method has problems such as high cost and long reaction time. This makes the sintering of mullite ceramics consume a lot of energy, and the requirements for production equipment are also very high, which makes the cost of the enterprise high. Therefore, reducing the sintering temperature of mullite ceramics is an urgent problem that related companies need to solve. Such a high sintering temperature will also affect the porosity and volume density of the sample, the flexural strength of the sample, and the cross-sectional morphology of the sample. However, the poor room-temperature mechanical properties of mullite porous ceramics have also become a major obstacle to its practical application. In addition, in actual production, mullite porous ceramics generally have problems such as high sintering temperature, harsh conditions for synthesizing high-performance materials, and the inability to achieve both high strength and high porosity.

[0003] In recent years, low-temperature sintering technology has become a research hotspot, aiming to reduce energy consumption and production costs by lowering the sintering temperature. The realization of low-temperature sintering usually relies on new sintering aids and optimized formula design. However, for porous mullite ceramics, how to achieve excellent mechanical properties at high porosity remains a technical challenge that needs to be overcome. Although porous mullite ceramics have excellent high-temperature resistance, they are brittle and prone to cracking during use. In order to improve its crack resistance and durability, researchers have conducted a lot of exploration in toughening mechanisms. For example, by introducing fiber reinforcement, phase change materials and nanoparticles, the crack resistance and toughness of ceramics can be effectively improved.

[0004] In summary, developing a porous mullite ceramic that can be sintered at low temperatures and simultaneously improving its toughening performance is of great significance for reducing production costs and enhancing material properties. This can not only promote the development of mullite ceramics in application fields such as filtration, catalysis, and heat insulation, but also bring double advantages of economic and environmental benefits to related enterprises. Through continuous technological innovation and material optimization, it is expected to achieve low-temperature sintering of mullite ceramics, thereby opening a new chapter in the field of high-performance ceramic materials. Summary of the Invention

[0005] The embodiment of the present application provides a preparation method of a low-temperature sintering self-reinforced mullite whisker porous ceramic, which can reduce the sintering temperature and improve the toughening performance of the porous ceramic at the same time.

[0006] On the one hand, the embodiment of the present application provides a low-temperature sintering self-reinforced mullite whisker porous ceramic. Calculated by mass fraction, its raw materials are composed of the following components: Al 2 O 3 : 52 - 72 wt%, SiO 2 : 20 - 28 wt%, AlF 3 ·3H 2 O: 4 - 12 wt%, MoO 3 : 5 - 20 wt%, B 2 O 3 : 2 - 8 wt%, Li 2 CO 3 : 1 - 5 wt%, Starch: 2 - 6 wt%, The sum of the above components is 100 wt%.

[0007] The starch is one or more of kudzu root powder, water chestnut powder, sweet potato powder, and corn starch; preferably kudzu root powder.

[0008] On the other hand, the embodiment of the present application provides a preparation method of a low-temperature sintering self-reinforced mullite whisker porous ceramic, including the following steps: 1) Mix Al 2 O 3 , SiO 2 , AlF 3 ·3H 2 O, MoO 3 , B 2 O 3 , Li 2 CO 3 , and kudzu root powder in proportion; the mass ratio of each component is: Al2 O 3 : 52% - 72%, SiO 2 : 20% - 28%, AlF 3 ·3H 2 O: 4% - 12%, MoO 3 : 5% - 20%, B 2 O 3 : 2% - 8%, Li 2 CO 3 : 1% - 5%, Starch: 2 - 6%, The sum of the above components is 100%.

[0009] 2) Put the raw materials and solvent mixed in step 1) into a ball mill, ball mill them, and then dry; the solvent is anhydrous ethanol or deionized water; 3) Place the dried raw materials in a mortar and mix and grind them until a uniform and delicate texture is achieved; subsequently, sieve the mixed powder through a 40 - 200 - mesh sieve, continue to add a binder for powder granulation, and finally obtain a uniformly textured mixed blank; 4) Load the mixed blank into a mold and press it on a tablet press at a forming pressure of 2 - 20 MPa to obtain a mullite whisker - reinforced mullite - based ceramic green body; 5) Carry out the sintering and cooling processes on the mullite whisker - reinforced mullite - based ceramic green body to obtain a self - reinforced mullite whisker porous ceramic.

[0010] The starch pore - former plays a key role in pore formation and structure regulation during the sintering process of the porous ceramic. During sintering, the starch decomposes when heated to generate gas, and the space it originally occupied forms pores. Using starch as a pore - former can avoid problems such as partial pore closure or disappearance due to too high sintering temperature, or low sample strength due to too low sintering temperature, thus obtaining better strength while ensuring high porosity.

[0011] The main raw materials for the preparation method are Al 2 O 3 and SiO 2 , supplemented with additives such as AlF 3 ·3H 2 O, MoO 3 , B 2 O 3 and Li 2 CO 3 etc. The process of in - situ whisker generation method and solid - phase sintering method is comprehensively adopted. During sintering, AlF3 · 3H 2 The catalytic effect of O enables mullite crystal nuclei to form mullite whiskers in a one-dimensional growth mode of screw dislocations, which are uniformly distributed in the porous ceramic, thus realizing the self-reinforcement effect of the ceramic. At the same time, MoO 3 , B 2 O 3 and Li 2 CO 3 addition can promote the mullitization reaction.

[0012] Preferably, in the preparation method of the strong mullite whisker porous ceramic, the mass ratio of the raw materials, the solvent, and the grinding balls in the ball mill in step 2) is 2:3:5.

[0013] Preferably, the particle size of the mixed powder after sieving in step 2) is 200 μm.

[0014] Preferably, in step 3), the mass ratio of the binder is 1-5 wt%; the binder is PVA (polyvinyl alcohol).

[0015] Preferably, the sintering in step 5) includes heating, debinding, and heat preservation, specifically: placing the specimen in a muffle furnace and heating it to 800-1300 °C at a rate of 5-10 °C / min for heat preservation, and the heat preservation time is 60-210 min; the heat preservation is preferably 120 min.

[0016] Preferably, heat preservation is carried out at 1000 °C. Compared with sintering at other temperatures, the ceramics prepared at 1000 °C have more excellent mechanical properties, and the whiskers grow uniformly and completely. In addition, the firing temperature at 1000 °C is lower, the required energy consumption is lower, carbon emissions are reduced, and the deformation and shrinkage of the ceramics at high temperatures are reduced.

[0017] Preferably, the specific conditions for cooling in step 5) are: after the sintering process is completed, the temperature is lowered to 500 °C at a cooling rate of 5 °C / min, and then naturally cooled to room temperature to obtain the required experimental samples.

[0018] Preferably, in step 1), ball milling is carried out at a ball milling rate of 400 r / min for 12 h.

[0019] The preparation method of the porous ceramic and the porous ceramic of the present invention have the following advantages: 1. Low-temperature sintering: By optimizing the material formula and sintering process, the present invention realizes the sintering of ceramics at a low temperature of 900 °C, which is 600 °C lower than the traditional method. This significantly reduced sintering temperature greatly reduces energy consumption, helps to reduce production costs, and alleviates the impact on the environment.

[0020] 2. Improvement of mechanical strength and durability: The method of generating self-reinforced mullite whiskers is adopted. During the sintering process of the ceramic, uniformly distributed mullite whiskers are formed through the one-dimensional growth mode of screw dislocations, thus significantly improving the mechanical strength and durability of the ceramic. In particular, the porous ceramic sintered at 1000 °C has excellent performance. This enables the ceramic to exhibit higher performance in various application fields.

[0021] 3. Reduction of energy consumption: Due to the reduction of the sintering temperature, the sintering time is shortened, and correspondingly, the energy consumption in the production process is reduced. This not only reduces the cost but also reduces the carbon footprint, which has a positive effect on environmental protection. Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0023] Figure 1 XRD patterns of the specimens at different sintering temperatures for the embodiments; Figure 2 SEM images of the specimens at different sintering temperatures for the embodiments; where (a) 800 °C, (b) 900 °C, (c) 1000 °C, (d) 1100 °C, (e) 1200 °C, (f) 1300 °C; Figure 3 Graphs of the bulk density and apparent density of the specimens at different sintering temperatures for the embodiments; Figure 4 Graph of the flexural strength of the specimens at different sintering temperatures for the embodiments. Detailed Description of the Embodiments

[0024] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below in conjunction with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present application by showing examples of the present application.

[0025] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0026] All raw materials used in the present invention are of analytical purity. During preparation, SiO 2 and Al 2 O 3 The raw materials are formulated at a molar ratio of Al 2 O 3 :SiO 2 =3:2. After high-temperature sintering, various crystal phases such as quartz, corundum, and mullite will be formed.

[0027] To solve the problems of the prior art, the embodiments of the present application provide a low-temperature sintering self-reinforced mullite whisker porous ceramic and its preparation method. According to Figure 1 the preparation process, the preparation method of the low-temperature sintering self-reinforced mullite whisker porous ceramic provided by the embodiments of the present application will be introduced first below.

[0028] A preparation method of a low-temperature sintering self-reinforced mullite whisker porous ceramic comprises the following steps: 1) Mix Al 2 O 3 , SiO 2 , AlF 3 ·3H 2 O, MoO 3 , B 2 O 3 , Li 2 CO 3 , starch, etc. in proportion; the mass ratio of each component is Al 2 O 3 : 52%-72%, SiO 2 : 20 %-28%, AlF 3 ·3H 2 O: 4%-12%, MoO 3 : 5%-20%, B 2 O 3 : 2%-8%, Li 2 CO3 : 1% - 5%, starch: 2 - 6%, and the sum of the above components is 100%; 2) Put the raw materials and solvent mixed in step 1) into a ball mill, ball mill them, and then dry; the solvent is anhydrous ethanol or deionized water; the mass ratio of the raw materials, solvent, and grinding balls in the ball mill is 2:3:5; 3) Place the dried raw materials in a mortar in step 2) and mix and grind them. Ball mill at a ball mill speed of 400 r / min for 12 hours until a uniform and delicate texture is achieved; subsequently, sieve the mixed powder through a 40 - 200 mesh sieve. The particle size of the mixed powder after sieving is 200 μm; continue to add a binder for powder granulation to finally obtain a uniformly textured mixed blank; the mass ratio of the binder is 1 - 5 wt%; the binder is PVA (polyvinyl alcohol).

[0029] 4) Load the mixed blank into a mold and place it on a tablet press to press at a forming pressure of 2 - 20 MPa to obtain a mullite whisker - reinforced mullite - based ceramic green body; 5) Place the mullite whisker - reinforced mullite - based ceramic green body in a muffle furnace and heat it at a rate of 5 - 10 °C / min to 800 - 1300 °C for heat preservation. The heat preservation time is 60 - 210 min to obtain a self - reinforced mullite whisker porous ceramic. The heat preservation is preferably 120 min. Heat it to 1000 °C for heat preservation.

[0030] After the sintering process ends, cool it at a cooling rate of 5 °C / min to 500 °C, and then naturally cool it to room temperature to obtain the required test sample.

[0031] The optimal ratio of each component of the porous ceramic of the present invention is as follows: by mass fraction, it is composed of the following components: Al 2 O 3 : 53.13 wt%, SiO 2 : 20.87 wt%, AlF 3 ·3H 2 O: 12 wt%, MoO 3 : 3.6 wt%, B 2 O 3 : 5.4 wt%, Li 2 CO 3 : 1 wt%, Kudzu powder: 4 wt%.

[0032] In the embodiments of the present invention, the specific proportioning scheme is shown in Table 1. Weigh the raw materials according to the proportions shown in Table 1. Put the weighed raw materials, absolute ethanol, and agate balls into an all-round planetary ball mill at a ratio of 2:3:5, and ball mill for 12 h at a speed of 400 r / min. The ball-milled raw materials are placed for drying. Take out the dried raw materials, grind them in a mortar, and add 3 wt% PVA aqueous solution as a binder to form a uniform mixed powder. Weigh 1.2 g of the mixed powder and press it into a bar-shaped specimen with a specification of 40 mm × 5 mm × 4 mm in a hydraulic jack or other tablet press at a molding pressure of 4 MPa. Subsequently, place the specimen in a muffle furnace and heat it to the required temperature of 800 - 1300 °C at a rate of 5 °C / min, and keep it warm for 120 min. Then cool the sample to 500 °C at a cooling rate of 5 °C / min and then naturally cool it to room temperature to obtain the required experimental sample, and test and characterize the obtained sample. The specific experimental process is as Figure 1 shown.

[0033]

[0034] Performance Test Perform porosity, bulk density, and mechanical property tests on the porous ceramics prepared in the examples. The specific implementation scheme is as follows: Use the Archimedes drainage method to measure the bulk density, apparent density, apparent porosity, and water absorption of the sample. The principle is that by completely immersing the sample in water, the volume of water displaced at this time is the same as the volume of the sample without open pores. The specific operation is as follows: Ⅰ. Weigh the sample using an electronic balance, and the mass m under natural drying conditions 0 . Ⅱ. Place the sample in boiling distilled water. After 2 h, there are no bubbles in the sample. Cool it to room temperature, take out the sample, wipe off the water on the surface of the sample, and weigh the sample mass m 1 . Ⅲ. Immerse the sample in distilled water at room temperature, and record the mass m of the sample immersed in water 2 .

[0035] Apparent density (g / cm 3 ):

[0036] Bulk density (g / cm 3 ):

[0037] Porosity (%):

[0038] Water absorption (%):

[0039] The three-point flexural strength of the sample was measured by a universal material testing machine, and the calculation formula is as follows:

[0040] Where: δ - flexural strength of the specimen, MPa; F - instantaneous loading pressure at specimen fracture, N; L - span between the two support points of the specimen, mm; W, H - represent the width and height of the specimen, respectively, mm.

[0041] Example 1 The component ratio contents in this example are as follows: Al 2 O 3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2 O 12 wt%, MoO 3 3.6 wt%, B 2 O 3 5.4 wt%, Li 2 CO 3 1 wt%, kudzu powder 4wt%. Heat up to 800 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.45 g / cm 3 , porosity is 53.23%, water absorption rate is 36.69%, and flexural strength is 10.38 MPa.

[0042] Example 2 The component ratio contents in this example are as follows: Al 2 O 3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2 O 12 wt%, MoO 3 3.6 wt%, B 2 O 3 5.4 wt%, Li 2 CO 3 1 wt%, kudzu powder 4wt%. Heat up to 900 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.36 g / cm 3 , porosity is 55.67%, water absorption rate is 41.07%, and flexural strength is 13.95 MPa.

[0043] Example 3 The component ratio contents in this example are as follows: Al 2 O3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2 O 12 wt%, MoO 3 3.6 wt%, B 2 O 3 5.4 wt%, Li 2 CO 3 1 wt%, kudzu powder 4wt% are fired into strip-shaped ceramics. The temperature is raised to 1000 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.40 g / cm 3 , the porosity is 54.77%, the water absorption rate is 39.25%, and the flexural strength is 42.02 MPa.

[0044] Example 4 In this example, the content of each component ratio is as follows: Al 2 O 3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2 O 12 wt%, MoO 3 3.6 wt%, B 2 O 3 5.4 wt%, Li 2 CO 3 1 wt%, kudzu powder 4wt% are fired into strip-shaped ceramics. The temperature is raised to 1100 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.37 g / cm 3 , the porosity is 55.85%, the water absorption rate is 40.68%, and the flexural strength is 27.17 MPa.

[0045] Example 5 In this example, the content of each component ratio is as follows: Al 2 O 3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2 O 12 wt%, MoO 3 3.6 wt%, B 2 O 3 5.4 wt%, Li 2 CO 31 wt%, 4 wt% of kudzu root starch are fired into strip-shaped ceramics. The temperature is raised to 1200 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.39 g / cm3, the porosity is 53.08%, the water absorption rate is 38.27%, and the flexural strength is 27.44 MPa.

[0046] Example 6 In this example, the content ratio of each component is as follows: Al 2 O 3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2 O 12 wt%, MoO 3 3.6 wt%, B 2 O 3 5.4 wt%, Li 2 CO 3 1 wt%, 4 wt% of kudzu root starch are fired into strip-shaped ceramics. The temperature is raised to 1300 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.38 g / cm 3 、porosity is 54.67%, water absorption rate is 39.72%, and flexural strength is 14.2 MPa.

[0047] Example 7 In this example, the content ratio of each component is as follows: Al 2 O 3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2 O 12 wt%, MoO 3 4 wt%, B 2 O 3 6 wt%, 4 wt% of kudzu root starch are fired into strip-shaped ceramics. The temperature is raised to 1200 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.47 g / cm 3 、porosity is 51.75%, water absorption rate is 38.72%, and flexural strength is 13.38 MPa.

[0048] Example 8 In this example, the content ratio of each component is as follows: Al 2 O 3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2O12 wt%, MoO 3 6 wt%, B 2 O 3 4 wt%, and 4 wt% of kudzu starch are sintered into strip-shaped ceramics. The temperature is raised to 1200 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.42 g / cm 3 , the porosity is 56.42%, the water absorption rate is 36.51%, and the flexural strength is 20.69 MPa.

[0049] Examples 9 - 12 In Examples 9 - 12, other components and preparation methods are the same as those in Example 3, but the sintering temperature is different from that in Example 3. Porous ceramics prepared at different sintering temperatures are subjected to performance tests, and the sintering temperatures and test results are shown in the following table.

[0050]

[0051] In the present invention, when the sintering temperature is in the range of 950 - 1050 °C, the performance of the prepared porous ceramics is optimal.

[0052] Comparative Example In the comparative example, other components and preparation methods are the same as those in Example 3, and different starches (sweet potato starch, water chestnut powder, kudzu starch, corn starch) are used as pore-forming agents to prepare porous ceramics. The porous ceramics prepared with different pore-forming agents are subjected to performance tests, and the test results are shown in the following table.

[0053]

[0054] In this example, the content ratio of each component is as follows: Al 2 O 3 53.13 wt%, SiO 2 20.87 wt%, AlF 3 •3H 2 O12 wt%, MoO 3 3.6 wt%, B 2 O 3 5.4 wt%, Li 2 CO 3 1 wt%, and 4 wt% of kudzu starch are sintered into strip-shaped ceramics. The temperature is raised to 1000 °C at a rate of 5 °C / min, and the holding time is 120 min. The bulk density of the sample is 1.40 g / cm 3 , the porosity is 54.77%, and the flexural strength is 42.02 MPa.

[0055] The average pore size of the starch pore former has a significant impact on the porosity and flexural strength of the porous ceramics. The starch pore former cracks during the sintering process, and microcracks generated by thermal stress inside the ceramic body form a pore structure. The larger the average pore size, the relatively larger the pore structure formed inside the porous ceramics. And the larger pore structure space provides a relatively sufficient growth space for the whiskers. Therefore, the whiskers in the porous ceramic specimens using kudzu powder as the pore former grow more completely and uniformly, and their mechanical properties are relatively excellent.

[0056] According to the examples, comparative examples, Figure 4 and test results, it can be known that: in the present invention, when sintering at 950 - 1050 °C, especially at 1000 °C, the physical and chemical properties and mechanical properties of the prepared porous ceramics are the best. This is because the reaction temperature of mullite is relatively high, and the present invention reduces its reaction temperature by adding a sintering aid; since the reaction is not sufficient at 800 °C and the whiskers do not grow completely, it will lead to low mechanical strength of the porous ceramics; while when reacting at 1100 °C - 1300 °C, the melting points of MoO 3 and Li 2 CO 3 are close, and too high a temperature will cause the two to produce a liquid phase, which is not conducive to the formation of mullite whiskers. At the sintering temperature of 900 - 1000 °C, the whiskers in the porous ceramic specimens grow relatively uniformly and completely, but due to the volume shrinkage phenomenon of the ceramic starting to occur at 1000 °C, the porosity decreases and the mechanical strength increases significantly. Therefore, the optimal sintering temperature in the present invention is 1000 °C.

[0057] Figure 1 The XRD patterns of the specimens at different sintering temperatures and Figure 2 the SEM images of the specimens at different sintering temperatures show that at 800 °C, the temperature is relatively low, and only partial mullitization reaction occurs, with only a small amount of mullite whiskers generated; while at the sintering temperature of 900 °C - 1300 °C, as the sintering temperature increases, the corundum phase and quartz phase inside the porous ceramic specimens gradually disappear and transform into the mullite phase.

[0058] The present invention combines the in-situ whisker generation method, the pore former addition method, and the sintering aid method to prepare porous ceramics with an in-situ mullite whisker skeleton. By precisely controlling the raw material ratio, sintering temperature, and pore former type, the optimal synthesis process of mullite ceramics is obtained. In addition, the synergistic effect of the sintering aid and the whisker catalyst promotes the growth of mullite crystal nuclei, realizing the low-temperature sintering of mullite ceramics.

[0059] The present invention proposes a new ceramic sintering technology. By optimizing the sintering process and raw material ratio, it aims to achieve low-temperature sintering and significantly improve the mechanical strength and durability of the ceramics, thereby expanding their application potential in the fields of engineering, electronics, and biomedicine.

[0060] As described above, this is only the specific implementation manner of the present application. Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein. It should be understood that the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present application.

Claims

1. A low-temperature sintered self-reinforced mullite whisker porous ceramic, characterized in that: In terms of mass fraction, its raw materials consist of the following components: Al2O3: 52-72 wt%, SiO2: 20-28 wt%, AlF3·3H2O:4-12 wt% MoO3: 5-20 wt%, B2O3: 2-8 wt%, Li2CO3: 1-5 wt%, Starch: 2-6 wt%, The sum of the above components is 100 wt%.

2. The low temperature sintered self-reinforced mullite whisker porous ceramic according to claim 1, characterized in that: The starch is one or more of kudzu root powder, water chestnut powder, sweet potato powder and corn starch; preferably kudzu root powder.

3. A method for preparing low-temperature sintered self-reinforced mullite whisker porous ceramics, characterized in that: The invention comprises the following preparation methods: 1) Mix Al2O3, SiO2, AlF3·3H2O, MoO3, B2O3, Li2CO3, starch, etc. according to the proportion; the mass ratio of each component is Al2O3: 52-72 wt%, SiO2: 20-28 wt%, AlF3·3H2O:4-12 wt% MoO3: 5-20 wt%, B2O3: 2-8 wt%, Li2CO3: 1-5 wt%, Starch: 2-6 wt%, The sum of the above components is 100 wt%; 2) putting the raw materials and solvent mixed in step 1) into a ball mill, grinding them and then drying them; the solvent is anhydrous ethanol or deionized water; 3) In step 2), the dried raw materials are placed in a mortar and mixed and ground until a uniform and fine texture is achieved; then, the mixed powder is sieved through a 40-200 mesh sieve, and a binder is continuously added to granulate the powder, and finally a mixed blank with a uniform texture is obtained; 4) placing the mixed green body into a mold, placing it on a tablet press and pressing it at a molding pressure of 2-20 MPa to obtain a mullite whisker reinforced mullite-based ceramic green body; 5) Sintering and cooling the mullite whisker reinforced mullite-based ceramic green body to obtain a self-reinforced mullite whisker porous ceramic.

4. The method for preparing the low temperature sintered self-reinforced mullite whisker porous ceramic according to claim 3, characterized in that: In step 2), the mass ratio of the raw material, the solvent and the grinding balls in the ball mill is 2:3:

5.

5. The method for preparing the low temperature sintered self-reinforced mullite whisker porous ceramic according to claim 3, characterized in that: The particle size of the mixed powder after sieving in step 2) is 200 μm.

6. The method for preparing the low temperature sintered self-reinforced mullite whisker porous ceramic according to claim 3, characterized in that: The mass ratio of the adhesive described in step 3) is 1-5 wt %; the adhesive is PVA (polyvinyl alcohol).

7. The method for preparing the low temperature sintered self-reinforced mullite whisker porous ceramic according to claim 3, characterized in that: Step 5) sintering includes heating, debinding, and heat preservation, specifically: placing the sample in a muffle furnace and heating it to 800-1300 °C at a rate of 5-10 °C / min for 60-210 min; the heat preservation time is preferably 120 min.

8. The method for preparing the low temperature sintered self-reinforced mullite whisker porous ceramic according to claim 7, characterized in that: The temperature was raised to 1000 °C and kept warm.

9. The method for preparing the low temperature sintered self-reinforced mullite whisker porous ceramic according to claim 3, characterized in that: Step 5) The specific cooling conditions are: after the sintering process is completed, the temperature is cooled to 500 °C at a cooling rate of 5 °C / min, and then naturally cooled to room temperature to obtain the required experimental samples.

10. The method for preparing the low temperature sintered self-reinforced mullite whisker porous ceramic according to claim 3, characterized in that: In step 1), the mixture was ball milled at a speed of 400 r / min for 12 h.

Images