阅读说明：本技术 一种纳米微孔刚玉的制备方法 (Preparation method of nano microporous corundum ) 是由 何健 吕戌生 张嘉良 张家勤 于 2019-08-08 设计创作，主要内容包括：本发明公开了一种微孔刚玉制备方法,包括以下步骤：将多种原料混合研磨成一定细度的粉体后进行制坯,坯体在1700~1950℃条件下烧结后即制得微孔刚玉。采用原料质量组分和种类为：60~100%工业氧化铝,0~20%α-氧化铝,0~30%γ-氧化铝,0~10%氢氧化铝,0~3%聚乙烯醇。本发明提供的微孔刚玉制备方法简单,可工业化生产,产品主要特征为刚玉晶体内部含有大量亚微米、纳米级封闭气孔,热导率低,具有较好的抗热震性、抗渣侵蚀性和节能保温性能,耐火度高,可代替烧结刚玉。(The invention discloses a preparation method of microporous corundum, which comprises the following steps: mixing and grinding a plurality of raw materials into powder with certain fineness, then preparing a blank, and sintering the blank at 1700-1950 ℃ to obtain the microporous corundum. The raw materials comprise the following components in parts by mass: 60-100% of industrial alumina, 0-20% of alpha-alumina, 0-30% of gamma-alumina, 0-10% of aluminum hydroxide and 0-3% of polyvinyl alcohol. The microporous corundum provided by the invention has the advantages of simple preparation method, industrial production and low thermal conductivity, and can replace sintered corundum, and the product is mainly characterized in that a large number of submicron and nanoscale closed air holes are contained in corundum crystals, has good thermal shock resistance, slag erosion resistance and energy-saving and heat-insulating properties, and has high refractoriness.)

1. A preparation method of microporous corundum is characterized by comprising the following steps: grinding all components in the raw materials uniformly in a ball mill, then preparing a blank, wherein the mass of the blank is 10-50 g, and then sintering at 1700-1950 ℃ for 1-3 h to obtain microporous corundum;

The raw materials comprise the following components in percentage by mass: 60-100% of industrial alumina, 0-20% of alpha-alumina, 0-30% of gamma-alumina and 0-10% of aluminum hydroxide.

2. The method for preparing the microporous corundum according to claim 1, wherein the content of Al2O3 in the industrial alumina is not less than 99%, the particle size of the industrial alumina is not more than 0.2mm, and the specific surface area of the industrial alumina is 60-100 m 2/g.

3. A method for preparing microporous corundum according to claim 1, characterized in that the content of Al2O3 in the alpha-alumina is not less than 99%, the grain size is not more than 0.2mm, and the content of alpha phase is 50-100%.

4. The method for preparing the microporous corundum according to claim 1, wherein the content of Al2O3 in the gamma-alumina is not less than 99%, the particle size of the gamma-alumina is not more than 0.2mm, and the content of gamma phase is 50-100%.

5. A method for preparing microporous corundum according to claim 1, characterized in that the Al2O3 content of the aluminum hydroxide is not less than 64%, and the grain size is not more than 0.2 mm.

6. A method for preparing microporous corundum according to claim 1, characterized in that the polyvinyl alcohol is industrial grade polyvinyl alcohol, the content is more than 99%, and the grain size is less than or equal to 5 mm.

7. The method for preparing the microporous corundum according to claim 1, wherein the ball mill is a gap type or continuous type ball mill, and raw materials of the components are fully ground into uniformly mixed powder with the average particle size of 2-10 μm in the ball mill.

8. A method for preparing microporous corundum according to claim 1, characterized in that the blank-making process is balling or briquetting, and a 0-10% polyvinyl alcohol aqueous solution is used as a bonding agent during blank making.

9. A preparation method of microporous corundum according to claim 1, characterized in that a high-temperature shaft kiln or other high-temperature kilns are selected to be sintered for 1-3 hours at 1700-1950 ℃, the closed porosity of the prepared microporous corundum is 3-15%, a large number of submicron and nanoscale closed pores are contained in crystals, and the thermal conductivity is reduced by 10-50% compared with that of sintered corundum and plate-shaped corundum.

10. a method for preparing microporous corundum according to claim 1, characterized in that, during the blank-making process, the mould used for limiting the corundum size adopts the following structural form: the mould comprises an inner layer and an outer layer, an interlayer is formed between the inner layer and the outer layer, and the inner layer forms a mould cavity;

The die is provided with a material injection hole for injecting powder into the die cavity and a water injection hole for injecting water into the die cavity; the mould is also provided with a pressure adjusting hole for injecting a high-pressure medium into the interlayer;

The mould is made of elastic materials, so that the inner layer deforms under the action of pressure, and the size of a mould cavity formed by the inner layer changes along with the quantity of injected powder and the pressure of a medium in the interlayer.

Technical Field

The invention belongs to the technical field of corundum refractory materials, and particularly relates to a preparation method of microporous corundum.

background

With the development of steel-making technology, a ladle is changed from an original molten steel container with a single function into an external refining device with a complex function, and the inner lining refractory material of the ladle needs to bear high temperature and resist scouring and erosion of molten steel and molten slag. The compactness and high strength of the refractory material are pursued for a long time, the erosion resistance and the corrosion resistance of the ladle lining can be improved to a certain degree, but the thermal shock resistance is unfavorable, and the heat stripping has a great influence on the service life of the refractory material in a refractory material damage mode.

The microporosity of the refractory material is a development trend in the technical field of the current refractory material, and aims to improve the thermal shock resistance of the material and have certain thermal insulation performance by improving the closed micropores in the material on the basis of keeping the basic performances such as the strength, the erosion resistance and the like of the refractory material not to be reduced, and particularly reduce the heat loss of thermal equipment and the energy consumption when being used for a working lining, thereby being beneficial to realizing the integration of long service life, high efficiency, energy conservation and consumption reduction; although the existing light refractory material has good energy-saving effect, the material cannot resist erosion and scouring due to low strength, is mostly used in a non-working layer, and is difficult to be used in a working layer which is directly contacted with high-temperature melt, such as a ladle lining.

Disclosure of Invention

The invention provides a preparation method of microporous corundum, which is characterized by comprising the following steps: the prepared microporous corundum has the closed porosity of 3-15%, a large number of submicron and nanoscale closed pores are contained in the crystal, the thermal conductivity is reduced by 10-50% compared with that of sintered corundum and plate-shaped corundum, and the microporous corundum has better thermal shock resistance, slag erosion resistance and energy-saving and heat-insulating properties.

In order to realize the task, the technical scheme adopted by the invention is as follows: mixing and grinding a plurality of component raw materials into powder with certain fineness, then preparing a blank, and sintering the blank at 1700-1950 ℃ to obtain the microporous corundum.

The types and the mass ratio of the adopted raw materials are as follows: 60-100% of industrial alumina, 0-20% of alpha-alumina, 0-30% of gamma-alumina, 0-10% of aluminum hydroxide and 0-3% of polyvinyl alcohol.

The raw materials of the components are mixed in a mixer for 1-20 min in proportion and then are ground into powder with the average particle size of 2-10 mu m in a ball mill, the powder is made into a spherical shape or other shapes by blank making equipment, 0-10% concentration polyvinyl alcohol aqueous solution is used as a bonding agent, the mass of a blank is 10-50 g, the water content is 10-30%, the blank is dried by a drying tower and then enters a shaft kiln to be sintered for 1-3 h at 1700-1950 ℃, and the sintered blank is crushed to obtain the microporous corundum.

The content of Al2O3 in the industrial alumina is more than or equal to 99%, the particle size of the industrial alumina is less than or equal to 0.2mm, and the specific surface area of the industrial alumina is 60-100 m 2/g.

The content of Al2O3 in the alpha-alumina is more than or equal to 99 percent, the particle size of the alpha-alumina is less than or equal to 0.2mm, and the content of alpha phase is 50-100 percent.

The content of Al2O3 in the gamma-alumina is more than or equal to 99 percent, the particle size of the gamma-alumina is less than or equal to 0.2mm, and the content of gamma phase is 50-100 percent.

The content of Al2O3 in the aluminum hydroxide is more than or equal to 64 percent, and the particle size of the aluminum hydroxide is less than or equal to 0.2 mm.

the polyvinyl alcohol is industrial grade polyvinyl alcohol, the content is more than 99 percent, and the grain diameter is less than or equal to 5 mm.

The ball mill is a gap type or continuous type ball mill, and raw materials of all components are fully ground into uniformly mixed powder with the average grain diameter of 2-10 mu m in the ball mill.

The blank making process is balling or pressing, and a 0-10% polyvinyl alcohol aqueous solution is used as a binding agent during blank making.

and (2) sintering the obtained microporous corundum for 1-3 hours at 1700-1950 ℃ by using a high-temperature shaft kiln or other high-temperature kilns, wherein the closed porosity of the prepared microporous corundum is 3-15%, a large amount of submicron and nanoscale closed pores are contained in the crystal, and the thermal conductivity is reduced by 10-50% compared with that of sintered corundum and tabular corundum.

During the blank making process, the adopted mould for limiting the corundum size adopts the following structural form: the mould comprises an inner layer and an outer layer, an interlayer is formed between the inner layer and the outer layer, and the inner layer forms a mould cavity;

the die is provided with a material injection hole for injecting powder into the die cavity and a water injection hole for injecting water into the die cavity; the mould is also provided with a pressure adjusting hole for injecting a high-pressure medium into the interlayer;

The mould is made of elastic materials, so that the inner layer deforms under the action of pressure, and the size of a mould cavity formed by the inner layer changes along with the quantity of injected powder and the pressure of a medium in the interlayer.

the preparation method of the microporous corundum provided by the invention is simple and suitable for industrial production, and the product is mainly characterized in that a large number of submicron and nanoscale closed air holes are contained in corundum crystals, the thermal conductivity is low, the microporous corundum has better thermal shock resistance, slag erosion resistance and energy-saving and heat-insulating properties, the refractoriness is high, and the microporous corundum can be used in refractory materials to replace sintered corundum or tabular corundum.

Detailed Description

In order to avoid repetition, the following raw materials and process parameters related to the present embodiment are uniformly described as follows, and are not repeated in the examples: the content of Al2O3 in the industrial alumina is more than or equal to 99 percent, and the grain diameter is less than or equal to 0.2 mm; the Al2O3 content of the aluminum hydroxide is more than or equal to 64 percent, and the particle size is less than or equal to 0.2 mm; the content of Al2O3 in the alpha-alumina is more than or equal to 99 percent, and the grain diameter is less than or equal to 0.2 mm; the Al2O3 content of the gamma-alumina is more than or equal to 99 percent, and the grain diameter is less than or equal to 0.2 mm; the content of the industrial grade polyvinyl alcohol is more than 99 percent, and the grain diameter is less than or equal to 5 mm.