CN107285806B - Porous corundum-magnesium aluminate spinel ceramic with nano-aperture and preparation method thereof - Google Patents
Porous corundum-magnesium aluminate spinel ceramic with nano-aperture and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a porous corundum-magnesia-alumina spinel ceramic with nano-pore diameter and a preparation method thereof, which has the technical scheme that fine aluminum hydroxide powder is heated to 280 ~ 450 ℃ and 800 ~ 1200 ℃ in sequence and is respectively subjected to heat preservation to obtain alumina powder with high porosity, the alumina powder with high porosity is prepared according to the following steps of proportioning 60 ~ 89wt%, 10 ~ 25wt% of magnesium chloride solution and 0.1 ~ 19wt% of magnesite micropowder, placing the alumina powder with high porosity in a vacuum mixer, vacuumizing to below 2.0kPa, adding the magnesium chloride solution and the magnesite micropowder, stirring to obtain a mixture, preserving the temperature of the mixture at 110 ~ 220 ℃, cooling, mechanically pressing and forming, drying, heating to 800 ~ 1200 ℃ and 1400 ~ 1600 ℃ in sequence and respectively preserving the temperature to obtain the porous corundum-magnesia-alumina spinel ceramic with nano-pore diameter.
Description
Technical Field
The invention belongs to the technical field of porous corundum-magnesium aluminate spinel ceramics. In particular to a porous corundum-magnesium aluminate spinel ceramic with nano-aperture and a preparation method thereof.
Background
The industrial kiln is key equipment for heating in high-temperature industries such as steel, nonferrous metallurgy, building materials and the like, and is also a large energy consumption household. The heat-insulating refractory material is an important basic material for reducing heat loss of an industrial kiln, and the development of the light and efficient heat-insulating refractory material has practical significance for energy conservation and emission reduction of high-temperature industry. The corundum-magnesium aluminate spinel ceramic has excellent high-temperature mechanical property and high-temperature chemical stability, and the porous material prepared by taking the corundum-magnesium aluminate spinel composite material as the raw material has wide application prospect in the aspects of heat insulation and heat preservation of industrial kilns.
There have been some researches on porous corundum-magnesia-alumina spinel ceramics, such as "porous corundum aggregate having core-shell structure and method for preparing the same" (CN 201410584015.7)In the patent technology, although the corundum-spinel aggregate containing the porous corundum balls with the core-shell structure is prepared by adopting a foam method, the corundum-spinel aggregate has the advantages of large pore size, low apparent porosity, large volume density and poor heat preservation effect; another example is "a porous spinel ceramic and process for its preparation" (CN 200610019551.8) patented technology, using magnesite and Al (OH)3Although the porous spinel ceramic is prepared by adopting an in-situ decomposition synthesis technology as a raw material, the prepared product has the advantages of lower strength, large pore diameter, high air permeability and poor medium erosion and permeation resistance.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a preparation method of a porous corundum-magnesium aluminate spinel ceramic with a nano pore diameter, and the prepared porous corundum-magnesium aluminate spinel ceramic with the nano pore diameter has the advantages of small volume density, low heat conductivity coefficient, high strength, low air permeability and strong medium erosion resistance.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
step one, placing the aluminum hydroxide fine powder into a high-temperature furnace, heating to 280-280 ~ 450 ℃ at the speed of 0.3 ~ 1.2.2 ℃/min, preserving heat for 1 ~ 4 hours, heating to 800-800 ~ 1200 ℃ at the speed of 1.5-1.5 ~ 2.3.3 ℃/min, preserving heat for 1 ~ 5 hours, and cooling to obtain the high-porosity aluminum oxide powder.
Step two, preparing materials according to the weight percentages of 60 ~ 89wt% of the high-porosity alumina powder, 10 ~ 25wt% of magnesium chloride solution and 0.1 ~ 19wt% of magnesite micropowder, placing the high-porosity alumina powder in a vacuum mixer, vacuumizing to below 2.0kPa, adding the magnesium chloride solution and the magnesite micropowder into the vacuum mixer, stirring for 10 ~ 15 minutes, and closing a vacuumizing system to obtain a mixture.
And step three, preserving the heat of the mixture for 2 ~ 5h at 110 ~ 220 ℃ for 2, cooling, performing machine pressing molding at 30 ~ 100MPa for 12 3536 h at 110 ℃, drying the molded blank for 12 ~ 36 h at 110 ℃, then placing the dried blank in a high-temperature furnace, heating to 800 ~ 1200 ℃ at the speed of 1 ~ 3 ℃/min, preserving the heat for 1 ~ 4h, heating to 1400 ~ 1600 ℃ at the speed of 3 ~ 5 ℃/min, preserving the heat for 3 ~ 8h, and cooling to obtain the porous corundum-magnesia-alumina spinel ceramic with the nano pore diameter.
The particle size of the aluminum hydroxide fine powder is less than 88 mu m, and Al of the aluminum hydroxide fine powder2O3The content was 60 ~ 66 wt%.
The particle size of the magnesite micro powder is less than 6 mu m, and the MgO content of the magnesite micro powder is 42 ~ 50 wt%.
MgCl of said magnesium chloride solution2The content was 10 ~ 30 wt%.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following positive effects:
the aluminum hydroxide fine powder adopted by the invention is decomposed at 280-280 ~ 450 ℃ to generate nano-scale pores to form alumina microcrystals, and the alumina microcrystals are subjected to a surface diffusion substance transmission process at 800-800 ~ 1200 ℃ to generate neck linkage between the alumina microcrystals so as to limit particle rearrangement in the middle and later sintering periods to obtain the alumina powder with high porosity, and the volume density of the porous corundum-magnesia-alumina spinel ceramic with nano-pore diameter can be reduced by adopting the alumina powder with high porosity.
The method introduces a solution containing magnesium chloride into the alumina powder with high porosity, enriches the magnesium chloride in the solution at the neck of the particle under the vacuum condition, and generates magnesium aluminate spinel with expanded volume through high-temperature in-situ reaction to prevent the combination and growth of nano pores.
The magnesite micropowder is introduced into the alumina powder with high porosity to fill gaps among the alumina powder, so that on one hand, pores among the alumina particles can be nanocrystallized, the strength of the porous corundum-magnesia-alumina spinel ceramic with nanometer apertures can be enhanced, and the air permeability and the heat conductivity coefficient of the product are reduced; on the other hand, the magnesite micro powder and the magnesium chloride solution react with alumina in situ to generate spinel, and the spinel is generated at the necks of the alumina particles to form connection among the necks of the alumina particles, so that rearrangement of the alumina particles in the high-temperature sintering process is prevented, and the strength and the medium corrosion resistance of the porous corundum-magnesia-alumina spinel ceramic with the nano-pore diameter are improved.
The nano-aperture porous corundum-magnesium aluminate spinel ceramic prepared by the invention has the apparent porosity of 25 ~ 60 percent and the volume density of 1.53 ~ 2.65.65 g/cm3The composite material has average pore size of 300 ~ 1000nm, compression strength of 50 ~ 150MPa and phase composition of corundum and magnesia-alumina spinel.
Therefore, the prepared porous corundum-magnesium aluminate spinel ceramic with the nano pore diameter has the characteristics of nano pore diameter, small volume density, low heat conductivity coefficient, high strength, low air permeability and strong medium erosion resistance.
Detailed Description
The invention is further described with reference to specific embodiments, without limiting its scope.
In order to avoid repetition, the raw materials in this specific embodiment are uniformly described as follows, and are not described in detail in the embodiments:
al of the aluminum hydroxide fine powder2O3The content was 60 ~ 66 wt%.
The MgO content of the magnesite micropowder is 42 ~ 50 wt%.
MgCl of said magnesium chloride solution2The content was 10 ~ 30 wt%.
Example 1
A porous corundum-magnesium aluminate spinel ceramic with nano-aperture and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step one, placing the aluminum hydroxide fine powder into a high-temperature furnace, heating to 280 ~ 450 ℃ at the speed of 0.3 ~ 1.2.2 ℃/min, preserving heat for 1 ~ 2 hours, heating to 800 ~ 1000 ℃ at the speed of 1.5 ~ 2.3.3 ℃/min, preserving heat for 1 ~ 3 hours, and cooling to obtain the high-porosity aluminum oxide powder.
Step two, preparing materials according to the proportion that the high-porosity alumina powder is 60 ~ 70wt%, the proportion of a magnesium chloride solution is 20 ~ 25wt% and the proportion of magnesite micropowder is 10 ~ 15wt%, putting the high-porosity alumina powder into a vacuum stirrer, vacuumizing to below 2.0kPa, adding the magnesium chloride solution and the magnesite micropowder into the vacuum stirrer, stirring for 10 ~ 15 minutes, and closing a vacuumizing system to obtain a mixture.
And step three, preserving the heat of the mixture for 2 ~ 3h at 110 ~ 220 ℃ for 2, cooling, performing machine pressing molding at 30 ~ 60MPa, drying the molded blank for 12 ~ 24 h at 110 ℃, then placing the dried blank in a high-temperature furnace, heating to 800 ~ 1000 ℃ at the speed of 1 ~ 3 ℃/min, preserving the heat for 1 ~ 3h, heating to 1400 ~ 1500 ℃ at the speed of 4 ~ 5 ℃/min, preserving the heat for 3 ~ 5h, and cooling to obtain the porous corundum-magnesia-alumina spinel ceramic with the nano pore diameter.
The particle size of the magnesite fine powder is less than 6 microns; the particle size of the aluminum hydroxide micro powder is less than 88 mu m.
The porous corundum-magnesium aluminate spinel ceramic with the nano pore diameter prepared by the embodiment is detected to have the apparent porosity of 40 ~ 60 percent and the volume density of 1.53 ~ 2.17.17 g/cm3The average pore diameter is 600 ~ 1000nm, and the compressive strength is 50 ~ 100 MPa.
Example 2
A porous corundum-magnesium aluminate spinel ceramic with nano-aperture and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step one, placing the aluminum hydroxide fine powder into a high-temperature furnace, heating to 280-280 ~ 450 ℃ at the speed of 0.3 ~ 1.2.2 ℃/min, preserving heat for 2 ~ 3 hours, heating to 1000-1000 ~ 1200 ℃ at the speed of 1.5-1.5 ~ 2.3.3 ℃/min, preserving heat for 3 ~ 5 hours, and cooling to obtain the high-porosity aluminum oxide powder.
Step two, preparing materials according to the weight percentages of 65 ~ 75% of the high-porosity alumina powder, 10 ~ 17% of the magnesium chloride solution and 15 ~ 19% of the magnesite micropowder, placing the high-porosity alumina powder in a vacuum mixer, vacuumizing to below 1.5kPa, adding the magnesium chloride solution and the magnesite micropowder into the vacuum mixer, mixing for 10 ~ 15 minutes, and closing a vacuumizing system to obtain a mixture.
And step three, preserving the heat of the mixture for 3 ~ 4h at 110 ~ 220 ℃ for cooling, performing machine pressing molding at 60 ~ 80MPa, drying the molded blank for 18 ~ 24 h at 110 ℃, then placing the dried blank in a high-temperature furnace, heating to 1000 ~ 1200 ℃ at the speed of 1 ~ 3 ℃/min, preserving the heat for 1 ~ 3h, heating to 1500 ~ 1600 ℃ at the speed of 4 ~ 5 ℃/min, preserving the heat for 3 ~ 5h, and cooling to obtain the porous corundum-magnesia-alumina spinel ceramic with the nano pore diameter.
The particle size of the magnesite fine powder is less than 4 mu m in the embodiment; the particle size of the aluminum hydroxide micro powder is less than 44 mu m.
The porous corundum-magnesium aluminate spinel ceramic with the nano-aperture prepared by the embodiment is detected to have the apparent porosity of 35 ~ 55 percent and the volume density of 1.69 ~ 2.33.33 g/cm3The average pore diameter is 500 ~ 800nm, and the compressive strength is 60 ~ 110 MPa.
Example 3
A porous corundum-magnesium aluminate spinel ceramic with nano-aperture and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step one, placing the aluminum hydroxide fine powder into a high-temperature furnace, heating to 280 ~ 450 ℃ at the speed of 0.3 ~ 1.2.2 ℃/min, preserving heat for 2 ~ 4 hours, heating to 800 ~ 1000 ℃ at the speed of 1.5 ~ 2.3.3 ℃/min, preserving heat for 1 ~ 3 hours, and cooling to obtain the high-porosity aluminum oxide powder.
Step two, preparing materials according to the weight percentages of 70 ~ 82wt% of the high-porosity alumina powder, 15 ~ 20wt% of the magnesium chloride solution and 2 ~ 11wt% of the magnesite micropowder, placing the high-porosity alumina powder in a vacuum stirrer, vacuumizing to below 0.5kPa, adding the magnesium chloride solution and the magnesite micropowder into the vacuum stirrer, stirring for 10 ~ 15 minutes, and closing a vacuumizing system to obtain a mixture.
And step three, preserving the heat of the mixture for 2 ~ 4h at 110 ~ 220 ℃ for 2, cooling, performing machine pressing molding at 70 ~ 90MPa, drying the molded blank for 16 ~ 30 h at 110 ℃, then placing the dried blank in a high-temperature furnace, heating to 800 ~ 1000 ℃ at the speed of 1 ~ 3 ℃/min, preserving the heat for 3 ~ 4h, heating to 1400 ~ 1500 ℃ at the speed of 3 ~ 4 ℃/min, preserving the heat for 5 ~ 8h, and cooling to obtain the porous corundum-magnesia-alumina spinel ceramic with the nano pore diameter.
The particle size of the magnesite fine powder is 2 ~ 4 microns, and the particle size of the aluminum hydroxide micro powder is 22 ~ 74 microns.
The porous corundum-magnesium aluminate spinel ceramic with the nano-aperture prepared by the embodiment is detected to have the apparent porosity of 30 ~ 50 percent and the volume density of 1.85 ~ 2.49.49 g/cm3The average pore diameter is 400 ~ 700nm, and the compressive strength is 80 ~ 130 MPa.
Example 4
A porous corundum-magnesium aluminate spinel ceramic with nano-aperture and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step one, placing the aluminum hydroxide fine powder into a high-temperature furnace, heating to 280-280 ~ 450 ℃ at the speed of 0.3 ~ 1.2.2 ℃/min, preserving heat for 3 ~ 4 hours, heating to 1000-1000 ~ 1200 ℃ at the speed of 1.5-1.5 ~ 2.3.3 ℃/min, preserving heat for 3 ~ 5 hours, and cooling to obtain the high-porosity aluminum oxide powder.
Step two, preparing materials according to the weight percentages of 75 ~ 89wt% of the high-porosity alumina powder, 10 ~ 18wt% of magnesium chloride solution and 0.1 ~ 10wt% of magnesite micropowder, placing the high-porosity alumina powder in a vacuum stirrer, vacuumizing to below 1.0kPa, adding the magnesium chloride solution and the magnesite micropowder into the vacuum stirrer, stirring for 10 ~ 15 minutes, and closing a vacuumizing system to obtain a mixture.
And step three, preserving the heat of the mixture for 3 ~ 5h at 110 ~ 220 ℃, cooling, performing mechanical compression molding at 80 ~ 100MPa, drying the molded blank for 24 ~ 36 h at 110 ℃, then placing the dried blank in a high-temperature furnace, heating to 1000 ~ 1200 ℃ at the speed of 1 ~ 3 ℃/min, preserving the heat for 3 ~ 4h, heating to 1500 ~ 1600 ℃ at the speed of 3 ~ 4 ℃/min, preserving the heat for 4 ~ 8h, and cooling to obtain the porous corundum-magnesia-alumina spinel ceramic with the nano-pore diameter.
The particle size of the magnesite fine powder is less than 2 mu m in the embodiment; the particle size of the aluminum hydroxide micro powder is less than 22 mu m.
The porous corundum-magnesium aluminate spinel ceramic with the nano pore diameter prepared by the embodiment is detected to have the apparent porosity of 25 ~ 45 percent and the volume density of 2.01 ~ 2.65.65 g/cm3The average pore diameter is 300 ~ 600nm, and the compressive strength is 100 ~ 150 MPa.
Compared with the prior art, the specific implementation mode has the following positive effects:
the method adopts the aluminum hydroxide fine powder which is decomposed at the temperature of 280 ~ 450 ℃ to generate nano-scale air holes to form alumina microcrystals, utilizes the surface diffusion substance transmission process of the alumina microcrystals at the temperature of 800 ~ 1200 ℃ to generate neck linkage between the alumina microcrystals so as to limit the particle rearrangement in the middle and later sintering stages to obtain the alumina powder with high porosity, and adopts the alumina powder with high porosity to reduce the volume density of the porous corundum-magnesia-alumina spinel ceramic with nano-pore diameter.
In the specific embodiment, a magnesium chloride-containing solution is introduced into high-porosity alumina powder, magnesium chloride in the solution is enriched at the neck of a particle under a vacuum condition, and magnesium aluminate spinel with expanded volume is generated through a high-temperature in-situ reaction to prevent the combination and growth of nanopores.
The specific embodiment introduces magnesite micropowder into the alumina powder with high porosity to fill gaps among the alumina powder, so that on one hand, pores among the alumina particles can be nanocrystallized, the strength of the porous corundum-magnesia-alumina spinel ceramic with nanometer pore diameter can be enhanced, and the air permeability and the heat conductivity coefficient of the product are reduced; on the other hand, the magnesite micro powder and the magnesium chloride solution react with alumina in situ to generate spinel, and the spinel is generated at the necks of the alumina particles to form connection among the necks of the alumina particles, so that rearrangement of the alumina particles in the high-temperature sintering process is prevented, and the strength and the medium corrosion resistance of the porous corundum-magnesia-alumina spinel ceramic with the nano-pore diameter are improved.
The nano-aperture porous corundum-magnesium aluminate spinel ceramic prepared by the specific embodiment is detected to have the apparent porosity of 25 ~ 60 percent and the volume density of 1.53 ~ 2.65.65 g/cm3The composite material has average pore size of 300 ~ 1000nm, compression strength of 50 ~ 150MPa and phase composition of corundum and magnesia-alumina spinel.
Therefore, the porous corundum-magnesium aluminate spinel ceramic with the nano pore diameter prepared by the embodiment has the characteristics of nano pore diameter, small volume density, low thermal conductivity, high strength, low air permeability and strong medium erosion resistance.
Claims (5)
1. A preparation method of porous corundum-magnesium aluminate spinel ceramic with nano pore diameter is characterized by comprising the following steps:
firstly, placing the aluminum hydroxide fine powder in a high-temperature furnace, heating to 280-450 ℃ at the speed of 0.3-1.2 ℃/min, preserving heat for 1-4 hours, heating to 800-1200 ℃ at the speed of 1.5-2.3 ℃/min, preserving heat for 1-5 hours, and cooling to obtain high-porosity aluminum oxide powder;
step two, preparing materials according to the weight percentages of 60-89% of the high-porosity alumina powder, 10-25% of magnesium chloride solution and 0.1-19% of magnesite micropowder, placing the high-porosity alumina powder in a vacuum mixer, vacuumizing to below 2.0kPa, adding the magnesium chloride solution and the magnesite micropowder into the vacuum mixer, stirring for 10-15 minutes, and closing a vacuumizing system to obtain a mixture;
step three, preserving the heat of the mixture for 2-5 hours at the temperature of 110-220 ℃, cooling, performing mechanical compression molding at the pressure of 30-100 MPa, and drying the molded blank for 12-36 hours at the temperature of 110 ℃; then placing the dried blank body in a high temperature furnace, heating to 800-1200 ℃ at the speed of 1-3 ℃/min, preserving heat for 1-4 h, heating to 1400-1600 ℃ at the speed of 3-5 ℃/min, preserving heat for 3-8 h, and cooling to obtain the porous corundum-magnesium aluminate spinel ceramic with the nano aperture;
the particle size of the aluminum hydroxide fine powder is less than 88 mu m;
the particle size of the magnesite micropowder is less than 6 microns.
2. The method of claim 1, wherein the Al of the aluminum hydroxide fine powder is Al2O3The content is 60-66 wt%.
3. The method for preparing the nano-aperture porous corundum-magnesium aluminate spinel ceramic according to claim 1, wherein the magnesite micropowder has a MgO content of 42-50 wt%.
4. The method of claim 1, wherein the MgCl of the magnesium chloride solution is MgCl2The content is 10-30 wt%.
5. A porous corundum-magnesium aluminate spinel ceramic with a nano pore size is characterized in that the porous corundum-magnesium aluminate spinel ceramic with the nano pore size is prepared by the preparation method of the porous corundum-magnesium aluminate spinel ceramic with the nano pore size according to any one of claims 1 to 4.
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| CN108821750B (en) * | 2018-07-10 | 2021-01-01 | 武汉科技大学 | Sintered magnesia with micro-nano composite pore structure and preparation method thereof |
| CN108840690A (en) * | 2018-07-10 | 2018-11-20 | 武汉科技大学 | A kind of micro-nano hierarchical porous structure magnesium aluminate spinel and preparation method thereof |
| CN108975941A (en) * | 2018-09-17 | 2018-12-11 | 淄博正邦知识产权企划有限公司 | A kind of alumina ceramic material and preparation method thereof with biocompatibility |
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