阅读说明：本技术 一种莫来石晶须增强钙长石多孔陶瓷及其原位合成制备方法以及隔热瓦 (Mullite whisker reinforced anorthite porous ceramic, in-situ synthesis preparation method thereof and heat-insulating tile ) 是由 李翠伟 武令豪 李�昊 王涵 付梦丽 李俊文 于 2019-11-29 设计创作，主要内容包括：本发明提供一种莫来石晶须增强钙长石多孔陶瓷及其原位合成制备方法以及隔热瓦,制备方法包括以下步骤：步骤S10,将碳酸钙、氧化铝、二氧化硅按照摩尔比1:1:2配料得到第一粉体；将氧化铝和二氧化硅按照摩尔比0.85:1配料得到第二粉体；将所述第一粉体、第二粉体以及占所述第二粉体质量10％-15％的三水氟化铝和所述占第二粉体摩尔数1％-30％的莫来石晶种与去离子水混合配制成浆料；步骤S20,将所述浆料加入明胶并进行发泡处理,获得泡沫浆料；步骤S30,将所述泡沫浆料倒入模具中并进行冷冻干燥,获得坯体；步骤S40,将干燥后的所述坯体放在马弗炉中进行烧结,获得所述莫来石晶须增强钙长石多孔陶瓷材料。本发明的制备方法得到的隔热瓦热导率低、强度高且使用寿命长。(The invention provides mullite whisker reinforced anorthite porous ceramic, an in-situ synthesis preparation method thereof and a heat insulation tile, wherein the preparation method comprises the following steps: step S10, mixing calcium carbonate, alumina and silicon dioxide according to a molar ratio of 1:1:2 to obtain first powder; mixing alumina and silicon dioxide according to a molar ratio of 0.85:1 to obtain second powder; mixing the first powder, the second powder, aluminum fluoride trihydrate accounting for 10-15% of the mass of the second powder, mullite crystal seeds accounting for 1-30% of the mole number of the second powder and deionized water to prepare slurry; step S20, adding gelatin into the slurry and carrying out foaming treatment to obtain foam slurry; step S30, pouring the foam slurry into a mold and carrying out freeze drying to obtain a blank; and step S40, sintering the dried blank in a muffle furnace to obtain the mullite whisker reinforced anorthite porous ceramic material. The heat insulation tile prepared by the preparation method disclosed by the invention is low in heat conductivity, high in strength and long in service life.)

1. The mullite whisker reinforced anorthite porous ceramic is characterized by being prepared from the following raw materials: calcium carbonate, alumina, silica, aluminum fluoride trihydrate and mullite crystal seeds, wherein the calcium carbonate, the alumina and the silica are used for synthesizing anorthite according to a molar ratio of 1:1:2, and the alumina and the silica are mixed with a certain amount of aluminum fluoride trihydrate and mullite crystal seeds according to a molar ratio of 0.85:1 to synthesize mullite whiskers; the mullite whisker reinforced anorthite porous ceramic has the porosity of 80-91 percent and the volume density of 0.29g/cm³-0.56g/cm³The compression strength is 0.7MPa-5.5MPa, and the vacuum thermal conductivity at room temperature is 0.06W/(m.K) -0.16W/(m.K); wherein, the open porosity and the volume density are measured by a boiling method based on Archimedes' law, the compressive strength is measured by a universal tester, and the room-temperature vacuum thermal conductivity is measured by a TTO component of a comprehensive physical property detection system.

2. An in-situ synthesis preparation method of mullite whisker reinforced anorthite porous ceramic is characterized by comprising the following steps:

step S10, mixing calcium carbonate, alumina and silicon dioxide according to a molar ratio of 1:1:2 to obtain first powder; mixing alumina and silicon dioxide according to a molar ratio of 0.85:1 to obtain second powder; mixing the first powder, the second powder, aluminum fluoride trihydrate accounting for 10-15% of the mass of the second powder, mullite crystal seeds accounting for 1-30% of the mole number of the second powder and deionized water to prepare slurry;

step S20, pouring out the slurry, adding gelatin and foaming agent, and rapidly stirring to obtain foam slurry;

step S30, pouring the foam slurry into a mold and carrying out freeze drying to obtain a blank;

and step S40, sintering the blank in a muffle furnace to obtain the mullite whisker reinforced anorthite porous ceramic material.

3. The in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic as claimed in claim 2, wherein in the step S10, the particle size of the calcium carbonate is 300nm-800nm, the particle size of the alumina is 300nm-500nm, the particle size of the silica is 1 μm-5 μm, the diameter of the mullite seed crystal is 0.2 μm-1 μm, the length-diameter ratio is 15:1-30:1, and the solid content of the slurry is 15% -35% by volume.

4. The method for preparing the mullite whisker-reinforced anorthite porous ceramic through in-situ synthesis according to claim 2, wherein in the step S10, the first powder is converted into anorthite, the second powder is converted into mullite, and the molar ratio of the anorthite to the mullite in the ingredients is (6-4): (4-6).

5. The in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic as claimed in claim 2, wherein in the step S10, the solid content of the slurry is 15-35 vol%.

6. The in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic as claimed in claim 2, wherein the step S10 comprises the following steps:

step S11, mixing the self-made mullite whiskers with absolute ethyl alcohol, carrying out ball milling for 15-60 min, and drying to obtain the mullite crystal seeds;

step S12, ball-milling deionized water, a dispersing agent, first powder, second powder, aluminum fluoride trihydrate and mullite crystal seeds for 16-20 h to obtain the slurry;

wherein the diameter of the self-made mullite seed crystal is 0.2-1 μm, and the length-diameter ratio is 15:1-30: 1; the adding amount of the aluminum fluoride trihydrate is 10-15% of the mass of the second powder; the adding amount of the mullite crystal seeds is 1 to 30 percent of the mole number of the second powder; the dispersant is ammonium polyacrylate, and the adding amount of the dispersant is 0.5-2% of the total mass of the first powder, the second powder, the aluminum fluoride trihydrate and the crystal seeds.

7. The in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic as claimed in claim 2, wherein the step S20 comprises the following steps:

step S21, adding the gelatin into deionized water, heating and dissolving;

step S22, adding the dissolved gelatin and the foaming agent solution into the slurry obtained in the step S10, and quickly stirring to obtain foam slurry;

wherein in the step S21, the gelatin accounts for 6-10% of the total mass of the solid, and the heating and dissolving temperature is 60-90 ℃; the foaming agent is sodium dodecyl sulfate, the foam stabilizer is lauryl alcohol, the ratio of lauryl alcohol to lauryl sulfate is 100:8, and the concentration of the foaming agent in the slurry is 0.5g/L-2 g/L.

8. The in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic as claimed in claim 2, wherein the step S30 specifically comprises the following steps:

step S31, pouring the foam slurry obtained in the step S20 into a mold, then placing the mold into a cold trap of a freeze dryer for pre-freezing for 30-60min, and then demolding to obtain a blank;

step S32, continuously freezing the demolded blank of S31 in a cold trap for 10-15 h;

step S33, taking out the blank body of S32, and placing the blank body in a freeze dryer for vacuum drying for 24-30 h with the vacuum degree of 5-10 Pa;

wherein the used mould is a paper mould which is easy to disassemble.

9. The in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic as claimed in claim 2, wherein the step S40 comprises the following steps: and putting the dried blank body in a muffle furnace, sealing the blank body in an alumina crucible, preserving heat for 1h at 100 ℃, preserving heat for 10 minutes at 600 ℃, preserving heat for 2h at 1200 ℃, preserving heat for 5h at 1350 ℃ for sintering, cooling to 300 ℃ at the speed of 5 ℃/min, and cooling to room temperature along with the furnace.

10. A thermal insulating tile comprising the mullite whisker reinforced anorthite porous ceramic of claim 1 made according to claim 2.

Technical Field

The invention relates to a preparation method of a ceramic block, in particular to mullite whisker reinforced anorthite porous ceramic, an in-situ synthesis preparation method thereof and a heat insulation tile comprising the mullite whisker reinforced anorthite porous ceramic.

Background

In recent years, the aerospace industry is rapidly developed, a large amount of heat is generated by friction between a spacecraft and air after the spacecraft enters the atmosphere, and higher requirements are put forward on a heat protection system for ensuring the normal operation of the spacecraft, so that the research and application of the heat insulation tile in the heat insulation system of the spacecraft are greatly concerned, and the research and development of the heat insulation material with super-strong, high-strength and high-heat-resistance to improve the safety performance of the heat insulation material are paid more attention. Anorthite porous ceramics are candidate materials due to excellent performance, but the development of the anorthite porous ceramics is limited by the lower compressive strength of the anorthite porous ceramics.

At present, two methods for improving the strength of anorthite porous ceramic are mainly adopted: firstly, a reinforcing phase is introduced, such as added mullite whiskers can effectively improve the strength of the anorthite porous ceramic, but the added mullite has a limited reinforcing effect due to shortened abrasion in the preparation process; secondly, a new preparation technology is developed, and a foam gel injection method of an acrylamide system is proved to be capable of obtaining a high-strength material, but the toxicity and the environmental pollution of the acrylamide system limit the industrialization process. Therefore, the method has great significance for developing an environment-friendly in-situ synthesis technology and preparing the mullite whisker reinforced anorthite porous ceramic with high porosity, high strength and low thermal conductivity.

Disclosure of Invention

In view of the above, the present invention aims to provide a mullite whisker reinforced anorthite porous ceramic and an in-situ synthesis preparation method thereof, so as to obtain a thermal insulation material with higher porosity and higher strength under the condition that the material strength is within the application range, reduce the thermal conductivity of the thermal insulation tile to a greater extent, and improve the comprehensive performance.

On the one hand, the invention provides a mullite whisker reinforced anorthite porous ceramic material.

The invention also provides an in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic.

The invention further provides a heat insulation tile.

In order to solve the technical problems, the invention adopts the following technical scheme:

the mullite whisker reinforced anorthite porous ceramic is prepared from the following raw materials: calcium carbonate, alumina, silica, aluminum fluoride trihydrate and mullite crystal seeds, wherein the calcium carbonate, the alumina and the silica are used for synthesizing anorthite according to a molar ratio of 1:1:2, and the alumina and the silica are mixed with a certain amount of aluminum fluoride trihydrate and mullite crystal seeds according to a molar ratio of 0.85:1 to synthesize mullite whiskers; the mullite whisker reinforced anorthite porous ceramic has the porosity of 80-91 percent and the volume density of 0.29g/cm³-0.56g/cm³The compression strength is 0.7MPa-5.5MPa, the vacuum thermal conductivity at room temperature is 0.06W/(m.K) -0.16W/(m.K), wherein, the open porosity and the volume density are measured by a boiling method based on Archimedes' law, the compression strength is measured by a universal tester, and the vacuum thermal conductivity at room temperature is measured by a TTO component of a comprehensive physical property detection system.

The in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic comprises the following steps:

step S10, mixing calcium carbonate, alumina and silicon dioxide according to a molar ratio of 1:1:2 to obtain first powder; mixing alumina and silicon dioxide according to a molar ratio of 0.85:1 to obtain second powder; mixing the first powder, the second powder, aluminum fluoride trihydrate accounting for 10-15% of the mass of the second powder, mullite crystal seeds accounting for 1-30% of the mole number of the second powder and deionized water to prepare slurry;

step S20, pouring out the slurry, adding gelatin and foaming agent, and rapidly stirring to obtain foam slurry;

step S30, pouring the foam slurry into a mold and carrying out freeze drying to obtain a blank;

and step S40, sintering the blank in a muffle furnace to obtain the mullite whisker reinforced anorthite porous ceramic material.

Further, in the step S10, the particle size of the calcium carbonate is 300nm-800nm, the particle size of the alumina is 300nm-500nm, the particle size of the silica is 1 μm-5 μm, the mullite seed crystal has a diameter of 0.2 μm-1 μm and an aspect ratio of 15:1-30: 1.

Further, in the step S10, the first powder is converted into anorthite, the second powder is converted into mullite, and the molar ratio of the anorthite to the mullite in the mixture is (6-4): (4-6).

Further, in the step S10, the solid content of the slurry is 15 vol% to 35 vol%.

Further, the step S10 includes:

step S11, mixing the self-made mullite whiskers with absolute alcohol, ball-milling for 15-30 min, and drying to obtain the mullite crystal seeds;

step S12, ball-milling deionized water, a dispersing agent, first powder, second powder, aluminum fluoride trihydrate and mullite crystal seeds for 16-20 h to obtain the slurry;

wherein the adding amount of the aluminum fluoride trihydrate is 10-15% of the mass of the second powder; the adding amount of the mullite crystal seeds is 1 to 30 percent of the mole number of the second powder; the dispersant is ammonium polyacrylate, and the adding amount of the dispersant is 0.5-2% of the total mass of the first powder, the second powder, the aluminum fluoride trihydrate and the crystal seeds.

Further, the step S20 includes:

step S21, adding the gelatin into deionized water, heating and dissolving;

step S22, adding the dissolved gelatin and the foaming agent solution into the slurry obtained in the step S10, and quickly stirring to obtain foam slurry;

wherein, in the step S21, the gelatin accounts for 8 percent of the total mass of the solid, and the heating and dissolving temperature is 60-90 ℃; the foaming agent is sodium dodecyl sulfate, the foam stabilizer is lauryl alcohol, the ratio of lauryl alcohol to lauryl sulfate is 100:8, and the concentration of the foaming agent in the slurry is 0.5g/L-2 g/L.

Further, the step S30 includes:

step S31, pouring the foam slurry obtained in the step S20 into a mold, then placing the mold into a cold trap of a freeze dryer for pre-freezing for 30-60min, and then demolding to obtain a blank;

step S32, continuously freezing the demolded blank of S31 in a cold trap for 10-15 h;

step S33, taking out the blank body of S32, and placing the blank body in a freeze dryer for vacuum drying for 24-30 h with the vacuum degree of 5-10 Pa;

wherein the used mould is a paper mould which is easy to disassemble.

Further, in the step S40, the dried green body is placed in a muffle furnace, the green body is sealed in an alumina crucible, and is subjected to heat preservation at 100 ℃ for 1 hour, at 600 ℃ for 10 minutes, at 1200 ℃ for 2 hours, at 1350 ℃ for 5 hours for sintering, and then cooled to 300 ℃ at a speed of 5 ℃/min, and then furnace-cooled to room temperature.

A thermal insulating tile according to an embodiment of the third aspect of the invention, comprising a mullite whisker reinforced anorthite porous ceramic material according to the above embodiment.

The technical scheme of the invention at least has one of the following beneficial effects:

1) according to the preparation method of the mullite whisker reinforced anorthite porous ceramic, the obtained mullite whisker reinforced anorthite porous ceramic has high phase purity, the elongated mullite whiskers in a three-dimensional interlaced net are distributed on the pore wall in a three-dimensional net shape to form a loose spherical pore wall, and anorthite grains with small grains are bonded between the mullite whiskers to form a structure similar to a nest shape, so that the mullite whisker reinforced anorthite porous ceramic has high porosity, high strength and good heat insulation performance, and when the obtained mullite whisker reinforced anorthite porous ceramic material is used as a heat insulation tile, the heat insulation tile can have longer service life;

2) the invention adopts ceramic powder with high purity and small granularity as raw material, and has higher phase purity because of no other impurity elements; because the granularity of the raw materials is small, the reaction activity is high, and the combination degree between particles is greatly improved; the sintering temperature is reduced by adjusting the ratio of aluminum to silicon and introducing a reaction auxiliary agent; seed crystals are introduced to improve the reaction activity, the diameter of the generated mullite whiskers is reduced, a three-dimensional network structure formed by interweaving high-length-diameter ratio whiskers is obtained, and the porous ceramic material with higher strength is obtained;

3) the invention adopts a foam gel injection method based on a gelatin gel system to prepare a porous ceramic material blank, gelatin is a high molecular polysaccharide and is formed by degrading collagen parts in connective tissues such as animal skin, bones, sarcolemma and the like, the invention has excellent biodegradability, no toxicity, no harm and environmental protection, and higher blank strength can be obtained under the condition of small addition amount; the gelatin solidification of the gelatin can be realized only by changing the temperature without introducing other additives, and the operation is simple;

4) the invention combines the foam pour-solidification process and the vacuum freeze-drying process, uses the mechanical foaming process to prepare the porous slurry, uses the low-temperature solidification and freezing to fix and stably exist small holes in a short time, and greatly reduces the cracking and polymerization of the air holes; the vacuum freeze drying speed is high, the blank body drying shrinkage is small, and microcracks caused by uneven drying shrinkage are reduced, so that the blank body strength is high; the pore diameter of the microstructure of the finally obtained porous ceramic material is uniform, the median pore diameter is smaller, and the material with high porosity, high strength and low thermal conductivity can be obtained;

5) according to the preparation method of the mullite whisker reinforced anorthite porous ceramic material, the controllability is high, and the phase composition, the porosity, the thermal conductivity, the compressive strength and the like of a sample are controlled by adjusting parameters such as the raw material ratio, the solid content and the like;

6) according to the mullite whisker reinforced anorthite porous ceramic material provided by the embodiment of the invention, the porosity is 80-91%, and the volume density is 0.29g/cm³-0.56g/cm³The compression strength is 0.7MPa-5.5MPa, and the thermal conductivity is 0.06W/(m.K) -0.16W/(m.K). As a heat insulating tile material, a heat insulating tile with higher porosity is obtained under the condition that the material strength is in an application range, and the heat insulating performance of the heat insulating tile can be improved to a greater extent and the weight of the heat insulating tile can be reduced.

Drawings

FIG. 1 is a flow chart of a method for preparing mullite whisker reinforced anorthite porous ceramic according to one embodiment of the invention;

FIG. 2 is an X-ray diffraction pattern of mullite whisker reinforced anorthite porous ceramic according to an embodiment of the invention, wherein (a) is the pattern of example 1 and (b) is the pattern of example 2;

FIG. 3 is a scanning electron microscope photograph of the micro-pore structure of mullite whisker reinforced anorthite porous ceramic material according to example 1 and example 2 of the present invention;

fig. 4 is a scanning electron microscope photograph of the micro-pore structure of the mullite whisker reinforced anorthite porous ceramic material according to example 3 of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.

The preparation method of the mullite whisker reinforced anorthite porous ceramic according to the embodiment of the invention is first described in detail.

The preparation method of the mullite whisker reinforced anorthite porous ceramic material disclosed by the embodiment of the invention comprises the following steps of:

step S10, mixing calcium carbonate, alumina and silicon dioxide according to a molar ratio of 1:1:2 to obtain first powder; mixing alumina and silicon dioxide according to a molar ratio of 0.85:1 to obtain second powder; mixing the first powder, the second powder, aluminum fluoride trihydrate accounting for 10-15% of the mass of the second powder, mullite crystal seeds accounting for 1-30% of the mole number of the second powder and deionized water to prepare slurry; when the first powder is converted into anorthite and the second powder is converted into mullite, the molar ratio of the anorthite to the mullite in the slurry is (6-4) to (4-6);

step S20, pouring out the slurry, adding gelatin and foaming agent, and rapidly stirring to obtain foam slurry;

step S30, pouring the foam slurry into a mold and carrying out freeze drying to obtain a blank;

and step S40, sintering the blank in a muffle furnace to obtain the mullite whisker reinforced anorthite porous ceramic material.

In other words, according to some embodiments of the present invention, calcium carbonate, alumina, and silica are used as raw materials to prepare the mullite whisker reinforced anorthite porous ceramic material, and first, calcium carbonate, alumina, and silica are mixed according to a molar ratio of 1:1:2 to prepare a first powder; mixing alumina and silicon dioxide according to a molar ratio of 0.85:1 to obtain second powder; adding aluminum fluoride trihydrate according to 12% of the mass of the second powder, and then mixing the materials according to the weight ratio of mullite: weighing the molar ratio of anorthite (6-4) to anorthite (4-6), mixing the anorthite with a dispersant and water to prepare slurry, combining foam gel injection and vacuum freeze drying processes to obtain a blank, and finally sintering the dried blank in a sintering furnace to obtain the mullite whisker reinforced anorthite porous ceramic material. Here, it is understood that, since a certain amount of aluminum is introduced using aluminum fluoride trihydrate, the compounding ratio of the aluminum component can be appropriately reduced when the second powder intended for synthesizing mullite is prepared.

Therefore, according to the in-situ synthesis preparation method of the mullite whisker reinforced anorthite porous ceramic, disclosed by the embodiment of the invention, the aluminum-silicon ratio in the raw materials is reduced for proportioning, so that the obtained mullite whisker reinforced anorthite porous ceramic material has higher purity, and mullite whiskers in the mullite whisker reinforced anorthite porous ceramic material are in a three-dimensional interwoven network and are tightly bonded with anorthite, so that the overall strength is improved. In addition, by adjusting the ratio of the first powder to the second powder (in other words, by adjusting the amount of mullite whiskers in the target product) and the ratio of the seed crystal, the porosity, thermal conductivity, compressive strength, bulk density, and the like of the sample can be controlled.

The microstructure of the porous material is very complex, when the environmental temperature rises, the process of phonon transmission is hindered by a plurality of factors, and phonons are scattered by the complex pore structure of the material, the phase interface of mullite whisker and anorthite crystal grains, the grain boundary between the anorthite crystal grains, the joint surface between the mullite whisker and the like, so the material has low thermal conductivity; the thermal expansion coefficients of anorthite and mullite are similar, namely the lightweight heat-insulating high-strength mullite whisker reinforced anorthite porous material has high strength and good thermal shock resistance; the high length-diameter ratio of the mullite whisker, the three-dimensional interweaving network formed by self lapping, the close combination of the mullite and anorthite crystal grains and the like all play a role in enhancing the mullite whisker synthesized in situ in the composite material, so the material has high strength; therefore, when the obtained mullite whisker reinforced anorthite porous ceramic material is used as a heat-insulating tile, the heat-insulating tile has longer service life.

In addition, the invention combines the foam pouring coagulation method and the vacuum freeze drying technology, uses the mechanical foaming technology to prepare the porous slurry, uses the freeze solidification and the freeze drying technology to fix and stably exist small holes in a short time, greatly reduces the fracture and the polymerization of air holes, and finally obtains the porous ceramic materialThe material has uniform pore diameter in the microstructure, smaller median pore diameter and higher porosity. The mullite whisker reinforced anorthite porous ceramic prepared by the preparation method of the mullite whisker reinforced anorthite porous ceramic has the porosity of 80-91 percent and the volume density of 0.29g/cm³-0.56g/cm³The compression strength is 0.7MPa-5.5MPa, and the thermal conductivity is 0.06W/(m.K) -0.16W/(m.K). The mullite whisker reinforced anorthite porous ceramic material has the characteristics of high strength and high porosity, and the heat insulation tile prepared by the mullite whisker reinforced anorthite porous ceramic material has higher strength, greatly prolongs the service life and has wider application range.

According to an embodiment of the present invention, in step S10, the raw material powder with higher purity and smaller particle size is blended, wherein the particle size of calcium carbonate is 300nm-800nm, the particle size of alumina is 300nm-500nm, the particle size of silica is 1 μm-5 μm, and the solid content of the slurry is 15 vol% -35 vol%. The eutectic point is lower due to two-phase sintering, so the sintering temperature is lower; and the addition of the seed crystal leads the reaction activity to be higher, the growth of the mullite whisker to be easier, and the porous ceramic material with higher strength can be obtained. In addition, the strength of the green body and the final ceramic body can be controlled by adjusting the content of the seed crystal.

According to an embodiment of the present invention, step S10 includes:

step S11, mixing the self-made mullite whiskers with absolute alcohol, carrying out ball milling for 30min, and drying to obtain the mullite crystal seeds;

step S12, adding deionized water and a dispersing agent into first powder, second powder, aluminum fluoride trihydrate accounting for 10% -15% of the mass of the second powder and mullite crystal seeds accounting for 1% -30% of the mole number of the second powder to form premixed slurry;

and step S13, ball-milling the premixed slurry for 16-20 h to obtain the slurry.

The crystal seed is self-made mullite whisker, the dispersing agent is ammonium polyacrylate, the mullite crystal seed is 1-30% of the mole number of the second powder, and the dispersing agent is 0.5-2% of the total mass of the first powder, the second powder, the aluminum fluoride trihydrate and the crystal seed.

Further, the step S20 may include:

step S21, adding the gelatin into deionized water, heating and dissolving;

step S22, adding the dissolved gelatin and the foaming agent solution into the slurry of S10 and rapidly stirring to obtain the foam slurry.

Wherein, in the step S21, the gelatin accounts for 8 percent of the total mass of the solid, and the heating and dissolving temperature is 60-90 ℃; the foaming agent is sodium dodecyl sulfate, the foam stabilizer is lauryl alcohol, the ratio of lauryl alcohol to lauryl sulfate is 100:8, and the concentration of the foaming agent in the slurry is 0.5g/L-2 g/L.

Therefore, according to the preparation method of the mullite whisker reinforced anorthite porous ceramic material, two processes of foam condensation and freeze drying are combined, the mechanical foaming process is used for preparing the porous slurry, and the freeze solidification and freeze drying are used for fixing and stably existing the pores in a short time, so that the cracking and polymerization of the pores are greatly reduced, and the finally obtained porous ceramic material has the advantages of uniform pore diameter in a microstructure, small median pore diameter and higher porosity.

According to an embodiment of the invention, in the step S30, the foam slurry is poured into a mold and frozen and solidified to obtain a blank, wherein the demolding time is 30-60 min; the freezing time is 10-15 h. And taking out the blank body, placing the blank body in a freeze dryer, and performing vacuum drying for 24-30 h at the vacuum degree of 5-10 Pa. And in the step S40, the dried green body is placed in a muffle furnace, the green body is sealed in an alumina crucible, the temperature is kept at 100 ℃ for 1h, 600 ℃ for 10 min, 1200 ℃ for 2h, 1350 ℃ for 5h for sintering, and the temperature is reduced to 300 ℃ at the speed of 5 ℃/min and then cooled to room temperature along with the furnace.

In the sintering process, the blank body is completely dried by keeping the temperature of the blank body at 100 ℃ for 1 hour, then the blank body is kept at 600 ℃ for 10 minutes to remove gelatin through cracking, then calcium carbonate is subjected to decomposition reaction to generate calcium oxide, calcium feldspar crystal nuclei are generated, mullite whiskers nucleate, and finally the blank body is sintered at 1350 ℃ to ensure that the mullite whiskers grow and mullite crystal grains are in acicular cross distribution in a three-dimensional space, the mullite whiskers are in three-dimensional net distribution on the pore walls, and a bird nest-like structure is formed between the mullite whiskers and the calcium feldspar crystal grains, so that the mullite whisker reinforced calcium feldspar porous ceramic has high porosity, high strength and good heat insulation performance.

The mullite whisker reinforced anorthite porous ceramic material prepared by the preparation method of the mullite whisker reinforced anorthite porous ceramic material has the porosity of 80-91 percent and the volume density of 0.29g/cm³-0.56g/cm³The compression strength is 0.7MPa-5.5MPa, the thermal conductivity is 0.06W/(m.K) -0.16W/(m.K), and the thermal insulation tile material can be used for obtaining the thermal insulation tile with higher porosity under the condition that the material strength and the thermal conductivity are in the application range, and the mass of the thermal insulation tile can be reduced to a greater extent through reducing the mass of the thermal insulation tile.

The preparation method of the mullite whisker reinforced anorthite porous ceramic material is described below by combining specific examples.

In the following examples, gelatin is used as a curing agent, but the present invention is not limited thereto, and any other curing reaction of a reagent known to those skilled in the art may be used. In the following examples, sodium lauryl sulfate was used as a foaming agent, but the present invention is not limited thereto, and those skilled in the art can perform foaming treatment using any other foaming agent. Such modifications are to be understood as falling within the scope of the present invention.