阅读说明：本技术 一种高温抗弯多孔陶瓷材料及其制备方法和应用 (High-temperature bending-resistant porous ceramic material and preparation method and application thereof ) 是由 林颖菲 骆智超 路建宁 王娟 郑开宏 于 2021-08-23 设计创作，主要内容包括：本发明公开了一种高温抗弯多孔陶瓷材料及其制备方法和应用,涉及陶瓷材料的制备技术领域。本发明基于内生反应,形成富含氧化铝陶瓷颗粒的核和包含镁铝尖晶石颗粒与硼莫来石晶须的壳,其技术方案是：将硼化物、Al-(2)O-(3)与MgO细粉按一定配比混合,随后与植物胶黏剂和去离子水湿混均匀形成浆料,添加毫米级氧化铝陶瓷颗粒混合,使得浆料良好包覆于氧化铝陶瓷颗粒表面,得到触变性陶瓷坯料,将其机压成型,干燥后置于高温炉内,实现内生反应烧结,制得高温抗弯多孔陶瓷材料。本发明具有成本低廉和工艺简单的特点,所制备的多孔陶瓷材料高温力学性能优,热震稳定性好,适用于高温隔热、熔体净化或烟尘过滤领域。(The invention discloses a high-temperature bending-resistant porous ceramic material, and a preparation method and application thereof, and relates to the technical field of preparation of ceramic materials. The invention is based on an endogenous reaction to form a core rich in alumina ceramic particles and a shell containing magnesia-alumina spinel particles and boron mullite whiskers, and the technical scheme is as follows: adding boride and Al 2 O 3 Mixing with MgO fine powder at a certain ratio, wet-mixing with plant adhesive and deionized water to form slurry, and adding millimeter powderMixing the grade alumina ceramic particles to ensure that the slurry is well coated on the surfaces of the alumina ceramic particles to obtain a thixotropic ceramic blank, mechanically pressing the thixotropic ceramic blank to form the thixotropic ceramic blank, drying the thixotropic ceramic blank, and then placing the thixotropic ceramic blank in a high-temperature furnace to realize endogenous reaction sintering to prepare the high-temperature anti-bending porous ceramic material. The invention has the characteristics of low cost and simple process, and the prepared porous ceramic material has excellent high-temperature mechanical property and good thermal shock stability, and is suitable for the fields of high-temperature heat insulation, melt purification or smoke dust filtration.)

1. The high-temperature bending-resistant porous ceramic material is characterized by comprising a plurality of core-shell structure units, wherein in each core-shell structure unit, a core is alumina ceramic particles, and a shell is a magnesium aluminate spinel and boron mullite whisker hybrid embedded layer;

and the core-shell structural units are interwoven and necked by boron mullite whiskers to form a through porous structure.

2. The high temperature, bending-resistant, porous ceramic material of claim 1, wherein the boron mullite whiskers comprise at least one of 2A1B boron mullite whiskers and 9A2B boron mullite whiskers.

3. The high-temperature bending-resistant porous ceramic material as claimed in claim 1, wherein the alumina ceramic particles are white corundum or brown corundum, and the particle size is 5-20 meshes.

4. A method for preparing a high-temperature bending-resistant porous ceramic material according to any one of claims 1 to 3, which comprises sintering a formed thixotropic ceramic blank to obtain the high-temperature bending-resistant porous ceramic material.

5. A high temperature according to claim 4The preparation method of the bending-resistant porous ceramic material is characterized in that the thixotropic ceramic blank is boride-Al₂O₃-a mixture of MgO slurry and alumina ceramic particles.

6. The method for preparing a high-temperature bending-resistant porous ceramic material as claimed in claim 5, wherein the boride-Al is₂O₃The preparation method of the MgO slurry comprises the following steps: adding boride-Al₂O₃Wet mixing MgO powder, plant adhesive and deionized water to obtain B₂O₃-Al₂O₃-a slurry of MgO;

preferably, boride-Al₂O₃-MgO powder, plant adhesive and deionized water in a mass ratio of 100: 3-12: 25-40;

preferably, the plant adhesive is one of starch glue, dextrin glue, carboxymethyl cellulose glue and lignin glue.

7. The method for preparing a high-temperature bending-resistant porous ceramic material as claimed in claim 6, wherein the boride-Al is₂O₃The preparation of the MgO powder includes: mixing boride and alpha-alumina (alpha-Al)₂O₃) Uniformly mixing magnesium oxide (MgO) by using a three-dimensional mixer;

preferably a boride, alpha-alumina (alpha-Al)₂O₃) And magnesium oxide (MgO) in a mass ratio of 1: 0.6-1: 0.4 to 0.6;

preferably, the boride is at least one of boron oxide and boric acid;

preferably, the boride, the aluminum oxide and the magnesium oxide are in industrial grade, and the particle size is 400-1000 meshes.

8. The method for preparing a high-temperature bending-resistant porous ceramic material as claimed in claim 5, wherein the boride-Al is₂O₃-the mass ratio of the MgO slurry to the alumina ceramic particles is 1: 4-6;

preferably, the boride-Al₂O₃Adding the-MgO slurry and the alumina ceramic particles into a three-dimensional mixer, and uniformly mixing for 2-6 h to ensure that boride-Al is formed₂O₃The MgO slurry is well coated on the surface of the alumina ceramic particles to form the thixotropic ceramic blank.

9. The method for preparing a high-temperature bending-resistant porous ceramic material according to claim 4, wherein the thixotropic ceramic blank further comprises forming before sintering;

the forming is that the thixotropic ceramic blank is formed by mechanical pressing under the condition of 10-80 MPa;

preferably, the molded blank is dried for 12-48 h at 80-120 ℃, the dried blank is placed in a high-temperature furnace, the temperature is raised to 1150-1300 ℃ at the speed of 2-5 ℃/min, the temperature is kept for 2-5 h, and the endogenetic reaction sintering is realized during the cooling.

10. The use of a high temperature bending resistant porous ceramic material as claimed in any one of claims 1 to 3 in the fields of high temperature insulation, melt purification or smoke filtration.

Technical Field

The invention relates to the technical field of preparation of ceramic materials, in particular to a high-temperature bending-resistant porous ceramic material and a preparation method and application thereof.

Background

The porous ceramic material has the advantages of low density, high specific surface area, high transmittance and the like, has wide application prospects in the fields of high-temperature heat insulation, smoke filtration, melt purification and the like, has low thermal expansion coefficient, good thermal shock resistance and low thermal conductivity at present, has excellent mechanical strength and chemical stability at high temperature, and is one of important candidate materials of a molten metal filter.

In the existing process for preparing the porous ceramic material, a mineralizer, a sintering aid, a plurality of aluminum salts in a mullite precursor solution and the like are often added, so that impurities are easily introduced into a product, and the product is not suitable for purifying a metal melt; in addition, the connection among pores of the existing porous ceramic product is a mixed combination of multiple forms and multiple groups of phases, so that poor thermal shock stability is easily caused by uneven thermal stress under high-temperature service, and meanwhile, the problems of complicated process flow, inconvenience for industrial production and the like can also occur in the process of preparing the porous ceramic material.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a high-temperature bending-resistant porous ceramic material, a preparation method and application thereof, so as to improve the problems.

The invention is realized by the following steps:

in a first aspect, an embodiment of the present invention provides a high-temperature bending-resistant porous ceramic material, which includes a plurality of core-shell structural units, wherein in each core-shell structural unit, a core is an alumina ceramic particle, and a shell is a magnesium aluminate spinel and boron mullite whisker hybrid embedded layer;

the core-shell structural units are connected by interweaving boron mullite whiskers in a neck manner to form a through porous structure.

In a second aspect, the embodiment of the present invention further provides a preparation method of a high-temperature bending-resistant porous ceramic material, which includes sintering the formed thixotropic ceramic blank to obtain the high-temperature bending-resistant porous ceramic material.

In a third aspect, the embodiment of the present invention further provides an application of the high-temperature bending-resistant porous ceramic material obtained in any one of the foregoing embodiments in the fields of high-temperature heat insulation, melt purification or smoke dust filtration.

The technical scheme of the invention has the following beneficial effects:

preparation of porous ceramic materials with core-shell structure by sintering with cladding reaction, based on alumina ceramic and boride-Al₂O₃The MgO slurry is subjected to an endogenous reaction in the sintering process to form a hybrid reinforced core-shell structural unit which takes alumina as a core and takes magnesium aluminate spinel particles and boron mullite whiskers in a chimeric distribution as a shell, and the boron mullite whiskers form an interwoven neck to connect all the core-shell structural units, so that the formation of a sawtooth occlusion interface among core-shell particles is promoted, and the strength of a product is increased; the high-temperature mechanical property and the thermal shock stability of the product are improved by utilizing the porous configuration of the core-shell structure and the specially distributed magnesium aluminate spinel and boron mullite whisker mixed phase. The invention takes alumina ceramic particles with a core-shell structure as a framework, and the boron mullite whisker overlapped with the magnesia-alumina spinel particles is in interweaving and necking connection to form a communicated macro-pore structure, so that the porous ceramic material with excellent high-temperature mechanical property is constructed, and the high-efficiency filtration and purification of molten metals such as aluminum alloy, regenerated aluminum and the like can be realized.

The preparation method of the porous ceramic material has the characteristics of low cost and simple process, and the prepared porous ceramic material has excellent high-temperature mechanical property and thermal shock stability.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic diagram of the internal structure of a high temperature bending-resistant porous ceramic material;

FIG. 2 is a scanning electron microscope image of a core-shell structure unit of the high temperature bending-resistant porous ceramic material prepared in example 1;

FIG. 3 is an enlarged view of the morphology of the shell structure of the high temperature bending resistant porous ceramic material of FIG. 2;

FIG. 4 is a scanning electron microscope image of the morphology of boron mullite whiskers in the high-temperature bending-resistant porous ceramic material prepared in example 1;

FIG. 5 is a scanning electron microscope image of the shell morphology of the high-temperature bending-resistant porous ceramic material prepared in comparative example 2;

FIG. 6 is a scanning electron microscope image of the shell morphology of the high-temperature bending-resistant porous ceramic material prepared in comparative example 3.

Description of the drawings: a-alumina ceramic particles; b-boron mullite whiskers; c-magnesium aluminate spinel particles; d-boron mullite whisker interweaved neck connection; f-closing holes between the shells; g-whiskers could not neck.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The porous ceramic material has the advantages of low density, high specific surface area, high transmittance and the like, and has wide application prospects in the fields of high-temperature heat insulation, smoke dust filtration, melt purification and the like, but in the prior art, the mineralizer, the sintering aid, a plurality of aluminum salts and the like in a mullite precursor solution are added during the preparation of the porous ceramic material, so that impurities are easily introduced into the product, and the porous ceramic material is not suitable for metal melt purification,in addition, the connection among pores of the existing porous ceramic product is a mixed combination of multiple forms and multiple groups of phases, and poor thermal shock stability is caused by uneven thermal stress under high-temperature service. In view of the above problems, the inventors have found that boride and Al are controlled₂O₃And the proportion of MgO, the obtained thixotropic ceramic blank can enable the magnesia-alumina spinel and the boron mullite whisker to be mixed, embedded and grown after being sintered, and the method does not add a mineralizer, a sintering aid and the like, does not additionally introduce impurities, and simultaneously controls the proportion of each component in the raw materials, so that the porous ceramic material has a single inter-pore connection form, and the thermal shock stability of the porous ceramic material is improved.

Some embodiments of the invention provide a high-temperature bending-resistant porous ceramic material, which comprises a plurality of core-shell structural units, wherein in each core-shell structural unit, a core is alumina ceramic particles, and a shell is a magnesium aluminate spinel and boron mullite whisker hybrid embedded layer; the core-shell structural units are connected by interweaving boron mullite whiskers in a neck manner to form a through porous structure.

The thermal expansion coefficient of the magnesia-alumina spinel is between that of alumina and boron mullite, so that the thermal stress effect of the core-shell structure unit can be effectively relieved when the magnesia-alumina spinel is in service at high temperature, and the thermal shock stability of a product is favorably improved; and the magnesia-alumina spinel has strong capability of absorbing iron oxide and slag corrosion resistance at high temperature, can effectively adsorb slag inclusions in molten metal, and further improves the purification efficiency of the product on the molten metal and prolongs the service life of the product.

The whisker form specific surface area of the boron mullite is large, so that the contact area with the filtered inclusions is effectively increased, and the inclusion capture efficiency is improved, thereby improving the purification effect of the product on molten metal; and the boron mullite whisker forms an interweaving neck part to connect each core-shell structural unit, so that the formation of a sawtooth occlusion interface between each core-shell structural unit can be promoted, and the strength of the product is increased.

In an alternative embodiment, the boron mullite whiskers include at least one of 2A1B boron mullite whiskers and 9A2B boron mullite whiskers.

In an optional embodiment, the alumina ceramic particles are white corundum or brown corundum, and the particle size is 5-20 meshes.

Some embodiments of the present invention provide a method for preparing the high-temperature bending-resistant porous ceramic material, which includes sintering the formed thixotropic ceramic blank to obtain the high-temperature bending-resistant porous ceramic material.

The preparation of the porous ceramic material with the core-shell structure unit is realized by cladding reaction sintering, and boride-Al is adopted₂O₃The proportion of the raw materials in the MgO slurry, the mass ratio of the raw materials to the alumina ceramic particles, the selection of the grain size of the alumina ceramic particles, the forming pressure, the sintering system and the like regulate and control the porous ceramic core-shell microstructure, so that the porous ceramic material which can be applied to higher temperature is prepared.

Some embodiments of the invention are based on alumina ceramics and boride-Al₂O₃The MgO slurry is subjected to an endogenous reaction in the sintering process to form a hybrid reinforced core-shell structural unit which takes alumina ceramic particles as a core and a hybrid embedded layer of magnesium aluminate spinel and boron mullite whisker as a shell, and the boron mullite whisker forms an interwoven neck to connect all core-shell structural units, so that the formation of a sawtooth occlusion interface between the core-shell structural units is promoted, and the strength of a product is increased; the thermal expansion coefficient of the magnesia-alumina spinel is between that of alumina and boron mullite, so that the thermal stress effect of the core-shell structure unit can be effectively relieved when the magnesia-alumina spinel is in service at high temperature, and the thermal shock stability of the product can be improved.

In an alternative embodiment, the thixotropic ceramic blank is boride-Al₂O₃-a mixture of MgO slurry and alumina ceramic particles.

In an alternative embodiment, the boride-Al₂O₃The preparation method of the MgO slurry comprises the following steps: adding boride-Al₂O₃Wet mixing MgO powder, plant adhesive and deionized water to obtain B₂O₃-Al₂O₃-a slurry of MgO.

Preferably, boride-Al₂O₃-MgO powder, plant adhesive and deionized water in a mass ratio of 100: 3-12: 25-40.

Preferably, the plant adhesive is one of starch glue, dextrin glue, carboxymethyl cellulose glue and lignin glue.

In an alternative embodiment, the boride-Al₂O₃The preparation of the MgO powder includes: mixing boride and alpha-alumina (alpha-Al)₂O₃) And the magnesium oxide (MgO) is uniformly mixed by a three-dimensional mixer.

Preferably a boride, alpha-alumina (alpha-Al)₂O₃) And magnesium oxide (MgO) in a mass ratio of 1: 0.6-1: 0.4 to 0.6.

The boride-Al prepared by the above proportion₂O₃After the MgO slurry is sintered by an endogenous reaction, the magnesia-alumina spinel tends to grow on alumina ceramic particles, the alumina ceramic particles are wrapped, and the boron mullite whiskers tend to neck on the outer side of the magnesia-alumina spinel to connect all core-shell structure units to form the porous ceramic material.

Preferably, the boride is at least one of boron oxide and boric acid.

Preferably, the boride, the aluminum oxide and the magnesium oxide are in industrial grade, and the particle size is 400-1000 meshes.

In an alternative embodiment, the boride-Al₂O₃-the mass ratio of the MgO slurry to the alumina ceramic particles is 1: 4 to 6.

The proportion can lead the alumina ceramic particles to be coated with boride-Al₂O₃The MgO slurry is completely coated, so that raw materials required by the endogenous reaction and the formation of the alumina ceramic particle framework with the core-shell structure are ensured.

Preferably, the boride-Al₂O₃Adding the-MgO slurry and the alumina ceramic particles into a three-dimensional mixer, and uniformly mixing for 2-6 h to ensure that boride-Al is formed₂O₃The MgO slurry is well coated on the surface of the alumina ceramic particles to form the thixotropic ceramic blank.

In an alternative embodiment, the thixotropic ceramic blank further comprises forming prior to sintering.

The forming is that the thixotropic ceramic blank is formed by mechanical pressing under the condition of 10-80 MPa.

Preferably, the molded blank is dried for 12-48 h at 80-120 ℃, the dried blank is placed in a high-temperature furnace, the temperature is raised to 1150-1300 ℃ at the speed of 2-5 ℃/min, the temperature is kept for 2-5 h, and the endogenetic reaction sintering is realized during the cooling.

The porous ceramic material obtained under the sintering system has better effects in structural stability and high-temperature mechanical property.

Some embodiments of the invention provide application of any one of the high-temperature bending-resistant porous ceramic materials in the fields of high-temperature heat insulation, melt purification or smoke dust filtration.

In some embodiments of the invention, ceramic particles with a core-shell structure are used as a framework, and a communicated macro-pore structure is formed by interweaving and necking boron mullite whiskers overlapping magnesium aluminate spinel particles, so that a porous ceramic material with excellent high-temperature mechanical properties is formed, and high-efficiency filtration and purification of molten metals such as aluminum alloy, secondary aluminum and the like can be realized.

The high-temperature bending-resistant porous ceramic material obtained by some embodiments of the invention has the following properties: the porosity is 15-45%, the bending strength at high temperature (1200 ℃) is more than 8MPa, the compressive strength at high temperature (800 ℃) is more than 8MPa, and the thermal shock resistance is excellent.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

Preparation B₂O₃-Al₂O₃-MgO powder: weighing industrial grade boron oxide (B) with the grain diameter of 400-1000 meshes₂O₃) Alpha-alumina (alpha-Al)₂O₃) And magnesium oxide (MgO) in a mass ratio of 1: 0.8:0.4, uniformly mixing in a three-dimensional mixer for 4 hours to obtain B₂O₃-Al₂O₃-MgO mixed powder;

preparation B₂O₃-Al₂O₃-MgO slurry: and (2) mixing the following components in percentage by mass as 100: 3: 25B₂O₃-Al₂O₃Mixing the-MgO mixed powder, starch glue and deionized water, adding into a mixer, and wet mixing for 2h to obtain B₂O₃-Al₂O₃-a slurry of MgO;

preparing a thixotropic ceramic blank: mixing the above B₂O₃-Al₂O₃The mass ratio of-MgO slurry to white corundum alumina ceramic particles is 1: 4, mixing materials, wherein the grain diameter of the white corundum alumina ceramic particles is 10-20 meshes, and mixing for 2 hours by adopting a three-dimensional mixer to ensure that B₂O₃-Al₂O₃The MgO slurry is well coated on the surface of the alumina ceramic particles to obtain a thixotropic ceramic blank;

molding: performing mechanical pressing on the thixotropic ceramic blank under the condition of 10MPa to obtain a blank body;

and (3) sintering: and (3) drying the molded blank in a constant-temperature drying box at the drying temperature of 120 ℃ for 12h, placing the dried blank in a high-temperature furnace, heating to 1300 ℃ at the speed of 2 ℃/min, preserving heat for 2h, cooling along with the furnace, and realizing the endogenous reaction sintering in the period.

As shown in fig. 2, the high-temperature bending-resistant porous ceramic material with a core-shell structure is prepared in this example, where a is a core, which is rich in alumina ceramic particles, outer layers of B and C are shells, B is boron mullite whisker, and C is magnesium aluminate spinel particles; the shell layer of fig. 2 is enlarged by 400 times, and a mixed embedded layer of magnesia-alumina spinel particles C and boron mullite whiskers B can be formed in the shell layer in fig. 3; in the figure 4, the position D is the interweaved neck connection of the boron mullite whiskers, and the single core-shell structural unit is combined into the high-temperature anti-bending porous ceramic material through the interweaved neck connection of the boron mullite whiskers.

The properties of the high-temperature bending-resistant porous ceramic material prepared by the embodiment are as follows: the porosity is 45%, the bending strength at high temperature (1200 ℃) is 8.1MPa, the compressive strength at high temperature (800 ℃) is 8.9MPa, the breaking strength retention rate of the thermal shock material at 800 ℃ at 20 times is 98%, the breaking strength retention rate of the thermal shock material at 900 ℃ at 20 times is 87% according to the detection of the industrial standard YB/T4018 thermal shock resistance test method of refractory products, and the thermal shock resistance is excellent.

Example 2

Preparation B₂O₃-Al₂O₃-MgO powder: weighing industrial grade boron oxide (B) with the grain diameter of 400-1000 meshes₂O₃) Alpha-alumina (alpha-Al)₂O₃) And magnesium oxide (MgO) in a mass ratio of 1: 1: 0.6 is evenly mixed in a three-dimensional mixer for 12 hours to obtain B₂O₃-Al₂O₃-MgO mixed powder;

preparation B₂O₃-Al₂O₃-MgO slurry: and (2) mixing the following components in percentage by mass as 100: 12: 25B₂O₃-Al₂O₃Mixing the-MgO mixed powder, dextrin glue and deionized water, and adding the mixture into a mixer for wet mixing for 8 hours to obtain B₂O₃-Al₂O₃-a slurry of MgO;

preparing a thixotropic ceramic blank: mixing the above B₂O₃-Al₂O₃The mass ratio of-MgO slurry to brown fused alumina ceramic particles is 1: 6 ingredients are mixed, the particle size of the brown corundum alumina ceramic particles is 5-10 meshes, and a three-dimensional mixer is adopted for mixing for 6 hours, so that B₂O₃-Al₂O₃The MgO slurry is well coated on the surface of the alumina ceramic particles to obtain a thixotropic ceramic blank;

molding: performing mechanical pressing on the thixotropic ceramic blank under the condition of 40MPa to obtain a blank body;

and (3) sintering: and (2) drying the molded blank in a constant-temperature drying box at the drying temperature of 100 ℃ for 24h, placing the dried blank in a high-temperature furnace, heating to 1150 ℃ at the speed of 5 ℃/min, preserving the temperature for 5h, cooling along with the furnace, and realizing endogenous reaction sintering during the period to prepare the high-temperature anti-bending porous ceramic material with the core-shell structure, wherein the core is rich in alumina ceramic particles, and the shell is a mixed embedding layer of magnesia-alumina spinel particles and boron mullite whiskers.

The properties of the high-temperature bending-resistant porous ceramic material prepared by the embodiment are as follows: the porosity is 32%, the bending strength at high temperature (1200 ℃) is 11.2MPa, the compressive strength at high temperature (800 ℃) is 12.3MPa, the breaking strength retention rate of the thermal shock material at 800 ℃ at 20 times is 97.5%, the breaking strength retention rate of the thermal shock material at 900 ℃ at 20 times is 86.7% and the thermal shock resistance is excellent according to the detection of the industrial standard YB/T4018 thermal shock resistance test method for refractory products.

Example 3

Preparation B₂O₃-Al₂O₃-MgO powder: weighing industrial grade boron oxide (B) with the grain diameter of 400-1000 meshes₂O₃) Alpha-alumina (alpha-Al)₂O₃) And magnesium oxide (MgO) in a mass ratio of 1: 0.6: 0.4, uniformly mixing in a three-dimensional mixer for 8 hours to obtain B₂O₃-Al₂O₃-MgO mixed powder;

preparation B₂O₃-Al₂O₃-MgO slurry: and (2) mixing the following components in percentage by mass as 100: 12: 40B₂O₃-Al₂O₃Mixing the-MgO mixed powder, the carboxymethyl cellulose gum and the deionized water, adding the mixture into a mixer for wet mixing for 4 hours to obtain B₂O₃-Al₂O₃-a slurry of MgO;

preparing a thixotropic ceramic blank: mixing the above B₂O₃-Al₂O₃-the mass ratio of MgO slurry to alumina ceramic particles is 1: 5, preparing materials, wherein the alumina ceramic particles consist of 40% of white corundum and 60% of brown corundum, the particle size of the white corundum is 10-20 meshes, the particle size of the brown corundum is 5-10 meshes, and mixing is carried out for 4 hours by adopting a three-dimensional mixer, so that B₂O₃-Al₂O₃The MgO slurry is well coated on the surface of the alumina ceramic particles to obtain a thixotropic ceramic blank;

molding: performing mechanical pressing on the thixotropic ceramic blank under the condition of 80MPa to obtain a blank body;

and (3) sintering: and (2) drying the molded blank in a constant-temperature drying box at the drying temperature of 80 ℃ for 48h, placing the dried blank in a high-temperature furnace, heating to 1200 ℃ at the speed of 3 ℃/min, preserving the temperature for 4h, cooling along with the furnace, and realizing endogenous reaction sintering during the period to prepare the high-temperature anti-bending porous ceramic material with the core-shell structure, wherein the core is rich in alumina ceramic particles, and the shell is a mixed embedding layer of magnesia-alumina spinel particles and boron mullite whiskers.

The properties of the high-temperature bending-resistant porous ceramic material prepared by the embodiment are as follows: the porosity is 15%, the bending strength at high temperature (1200 ℃) is 15.5MPa, the compressive strength at high temperature (800 ℃) is 16.3MPa, the breaking strength retention rate of the thermal shock material at 800 ℃ at 20 times is 98%, the breaking strength retention rate of the thermal shock material at 900 ℃ at 20 times is 87% according to the detection of the industrial standard YB/T4018 thermal shock resistance test method of refractory products, and the thermal shock resistance is excellent.

Example 4

Preparation B₂O₃-Al₂O₃-MgO powder: weighing industrial grade boron oxide (B) with the grain diameter of 400-1000 meshes₂O₃) Alpha-alumina (alpha-Al)₂O₃) And magnesium oxide (MgO) in a mass ratio of 1: 1: 0.4, uniformly mixing in a three-dimensional mixer for 6 hours to obtain B₂O₃-Al₂O₃-MgO mixed powder;

preparation B₂O₃-Al₂O₃-MgO slurry: and (2) mixing the following components in percentage by mass as 100: 8: 30B₂O₃-Al₂O₃Mixing the-MgO mixed powder, the lignin glue and the deionized water, adding the mixture into a mixer for wet mixing for 8 hours to obtain B₂O₃-Al₂O₃-a slurry of MgO;

preparing a thixotropic ceramic blank: mixing the above B₂O₃-Al₂O₃-the mass ratio of MgO slurry to alumina ceramic particles is 1: 5, preparing materials, wherein the alumina ceramic particles consist of 40% of brown corundum and 60% of white corundum, the particle size of the brown corundum is 10-20 meshes, the particle size of the white corundum is 5-10 meshes, and mixing is carried out for 3 hours by adopting a three-dimensional mixer, so that B₂O₃-Al₂O₃The MgO slurry is well coated on the surface of the alumina ceramic particles to obtain a thixotropic ceramic blank;

molding: mechanically pressing the thixotropic ceramic blank under the condition of 50MPa to obtain a blank body;

and (3) sintering: and (2) drying the molded blank in a constant-temperature drying oven at the drying temperature of 110 ℃ for 30h, placing the dried blank in a high-temperature furnace, heating to 1250 ℃ at the speed of 4 ℃/min, preserving the temperature for 3h, cooling along with the furnace, and realizing endogenous reaction sintering during the period to prepare the high-temperature anti-bending porous ceramic material with the core-shell structure, wherein the core is rich in alumina ceramic particles, and the shell is a mixed embedding layer of magnesia-alumina spinel particles and boron mullite whiskers.

The properties of the high-temperature bending-resistant porous ceramic material prepared by the embodiment are as follows: the porosity is 25%, the bending strength at high temperature (1200 ℃) is 13.8MPa, the compressive strength at high temperature (800 ℃) is 14.9MPa, the breaking strength retention rate of the thermal shock material at 800 ℃ at 20 times is 96.9%, the breaking strength retention rate of the thermal shock material at 900 ℃ at 20 times is 85.6% according to the detection of the industrial standard YB/T4018 thermal shock resistance test method of refractory products, and the thermal shock resistance is excellent.

Example 5

Preparation B₂O₃-Al₂O₃-MgO powder: weighing industrial grade boron oxide (B) with the grain diameter of 400-1000 meshes₂O₃) Alpha-alumina (alpha-Al)₂O₃) And magnesium oxide (MgO) in a mass ratio of 1: 1: 0.5, uniformly mixing in a three-dimensional mixer for 10 hours to obtain B₂O₃-Al₂O₃-MgO mixed powder;

preparation B₂O₃-Al₂O₃-MgO slurry: and (2) mixing the following components in percentage by mass as 100: 10: 35B of₂O₃-Al₂O₃mixing-MgO mixed powder, starch glue, dextrin glue and deionized water, wherein the starch glue and the dextrin glue have the same mass, and adding the mixture into a mixer for wet mixing for 8 hours to obtain B₂O₃-Al₂O₃-a slurry of MgO;

preparing a thixotropic ceramic blank: mixing the above B₂O₃-Al₂O₃-the mass ratio of MgO slurry to alumina ceramic particles is 1: 6, mixing the materials by a three-dimensional mixer for 6 hours, wherein the alumina ceramic particles consist of 50% of brown corundum and 50% of white corundum, the particle size of the brown corundum is 10-16 meshes, and the particle size of the white corundum is 10-16 meshes, so that B₂O₃-Al₂O₃The MgO slurry is well coated on the surface of the alumina ceramic particles to obtain a thixotropic ceramic blank;

molding: performing mechanical pressing on the thixotropic ceramic blank under the condition of 30MPa to obtain a blank body;

and (3) sintering: and (2) drying the molded blank in a constant-temperature drying oven at the drying temperature of 90 ℃ for 36h, placing the dried blank in a high-temperature furnace, heating to 1250 ℃ at the speed of 3 ℃/min, preserving the temperature for 3h, cooling along with the furnace, and realizing endogenous reaction sintering during the period to prepare the high-temperature anti-bending porous ceramic material with the core-shell structure, wherein the core is rich in alumina ceramic particles, and the shell is a mixed embedding layer of magnesia-alumina spinel particles and boron mullite whiskers.

The properties of the high-temperature bending-resistant porous ceramic material prepared by the embodiment are as follows: the porosity is 38%, the bending strength at high temperature (1200 ℃) is 9.5MPa, the compressive strength at high temperature (800 ℃) is 10.3MPa, the breaking strength retention rate of the thermal shock material at 800 ℃ at 20 times is 95.3%, the breaking strength retention rate of the thermal shock material at 900 ℃ at 20 times is 85.1% according to the detection of the industrial standard YB/T4018 thermal shock resistance test method of refractory products, and the thermal shock resistance is excellent.

Comparative example 1

The comparative example differs from example 1 only in the case of boride-Al₂O₃-MgO powder with silicon oxide (SiO)₂) Wherein boron oxide (B)₂O₃) Silicon oxide (SiO)₂) Alpha-alumina (alpha-Al)₂O₃) The mass ratio of magnesium oxide (MgO) to magnesium oxide (MgO) is 0.5:0.5:0.8: 0.4.

The shell layer of the core-shell structure unit of the high-temperature bending-resistant porous ceramic material obtained by the comparative example has silicon-containing mullite whisker and magnesia-alumina spinel particles, and the properties are as follows: the porosity is 45%, the bending strength at high temperature (1200 ℃) is 7.5MPa, the compressive strength at high temperature (800 ℃) is 8.0MPa, the breaking strength retention rate of the thermal shock material at 800 ℃ for 20 times is 92%, and the breaking strength retention rate of the thermal shock material at 900 ℃ for 20 times is 80%.

The mullite whisker component has larger influence on the thermal stability of the porous ceramic, the thermal stability of the silicon-containing mullite is weaker than that of the boron mullite, and the shell layer of the core-shell structure unit of the porous ceramic material formed by the comparative example is a mixed group phase, so that the thermal shock resistance of the product is negatively influenced.

Comparative example 2

This comparative example differs from example 1 only in that B₂O₃-Al₂O₃Mass of MgO slurry and alumina ceramic particlesThe amount ratio is 1: 3.

The core-shell structure unit of the high-temperature bending-resistant porous ceramic material obtained in the comparative example is shown in fig. 5, and the position F in fig. 5 can find that the shell layer has obvious closed pores, which is not beneficial to the filtering and purifying effect of the product.

Comparative example 3

This comparative example differs from example 1 only in that B₂O₃-Al₂O₃The mass ratio of the MgO slurry to the alumina ceramic particles is 1: 7.

The core-shell structure unit of the high-temperature bending-resistant porous ceramic material obtained by the comparative example is shown in fig. 6, and the incomplete shell formation, the exposure of part of alumina ceramic particles, the poor necking effect of mullite whiskers in part of the area and the unstable mechanical property of the product can be found at the position G in fig. 6.

The properties of the high-temperature bending-resistant porous ceramic materials obtained in comparative examples 2 and 3 are greatly different from those of example 1, which shows that boride-Al₂O₃The mass ratio of the MgO slurry to the alumina ceramic particles has a greater influence on the formation of the communicating macro-porous structure of the porous ceramic material.

Comparative example 4

The present comparative example is different from example 1 only in that the number of particle diameters of the alumina ceramic particles is less than 5 mesh.

The shell layer of the core-shell structure unit of the high-temperature bending-resistant porous ceramic material obtained by the comparative example is too thin, and the high-temperature mechanical property and the slag corrosion resistance of the product when the product is used for purifying a melt are influenced.

Comparative example 5

The comparative example is different from example 1 only in that the number of particle diameters of the alumina ceramic particles is larger than 20 mesh.

The shell layer of the core-shell structure unit of the high-temperature bending-resistant porous ceramic material obtained by the comparative example is thicker, the porosity of the product is lower, and the filtering efficiency of the product is lower.

The properties of the high-temperature bending-resistant porous ceramic materials obtained in comparative examples 4 and 5 are greatly different from those of the high-temperature bending-resistant porous ceramic material obtained in example 1, which shows that the particle size of the alumina ceramic particles has great influence on the shell structure of the core-shell structure unit of the porous ceramic material, and even influences the purification efficiency and the service life of the product.

Comparative example 6

The comparative example differs from example 1 only in that the pressure at which the thixotropic ceramic blank is formed in the press molding is 8 MPa.

The formed blank obtained by the comparative example is loose, deformation or collapse is easy to occur in the transfer drying process, the porosity of the obtained porous ceramic material is about 45 percent, the corresponding high-temperature (1200 ℃) bending strength is 6.1MPa, the high-temperature (800 ℃) compressive strength is less than 6.8MPa, and the high-temperature mechanical property is unstable.

Comparative example 7

The comparative example differs from example 1 only in that the pressure at which the thixotropic ceramic blank is formed in the press molding is 85 MPa.

The comparative example shows that part of alumina ceramic particles in the formed blank body are cracked, the coated slurry is extruded and lost, the porosity of the obtained porous ceramic material is less than 15%, and the connectivity of the pore structure is poor.

The high-temperature bending-resistant porous ceramic materials obtained in comparative examples 6 and 7 have larger differences from example 1, which shows that the forming pressure of the thixotropic ceramic blank has larger influence on the forming stability of the porous ceramic material.

Comparative example 8

The comparative example differs from example 1 only in that the high-temperature holding temperature at the time of sintering reaction was 1100 ℃.

The required boron mullite whiskers are difficult to form in the porous ceramic material obtained by the comparative example, wherein the necking effect among the core-shell structure units is poor, and the temperature of the sintering reaction has a great influence on the shell structure and the reaction connection effect of the core-shell structure units of the porous ceramic material.

In summary, some embodiments of the present invention are based on alumina ceramics and boride-Al₂O₃And carrying out an endogenous reaction on the MgO slurry in the sintering process to form a core-shell structural unit taking alumina as a core and the hybrid embedded layer of the magnesia-alumina spinel particles and the boron mullite whiskers as a shell. By reasonably adjusting boride-Al₂O₃Proportion of raw materials in MgO slurry and alumina ceramic powderThe mass ratio, the selection of the particle size of the alumina ceramic powder, the forming pressure, the sintering schedule and the like, and the porous ceramic core-shell microstructure is regulated and controlled, so that the porous ceramic material which can be applied to higher temperature is prepared, the high-temperature mechanical property and the thermal shock stability of the product are improved, and the high-efficiency filtration and purification effects on molten metals such as aluminum alloy, secondary aluminum and the like can be realized.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.