CN112794704A - SiC whisker reinforced corundum breathable refractory material and preparation method thereof - Google Patents

SiC whisker reinforced corundum breathable refractory material and preparation method thereof Download PDF

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CN112794704A
CN112794704A CN202110023671.XA CN202110023671A CN112794704A CN 112794704 A CN112794704 A CN 112794704A CN 202110023671 A CN202110023671 A CN 202110023671A CN 112794704 A CN112794704 A CN 112794704A
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corundum
spherical porous
refractory material
corundum particles
fine powder
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CN112794704B (en
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鄢文
陈茜琳
吴晗
陈俊峰
魏耀武
韩兵强
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Lengshuijiang Bosheng New Materials Co.,Ltd.
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Wuhan University of Science and Engineering WUSE
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Abstract

The invention relates to a SiC whisker reinforced corundum breathable refractory material and a preparation method thereof. The technical scheme is as follows: taking 15-20 wt% of modified spherical porous corundum particles I, 31-39 wt% of modified spherical porous corundum particles II and 17-25 wt% of modified spherical porous corundum particles III as aggregates, 2-4 wt% of magnesia fine powder, 10-22 wt% of corundum fine powder and 3-6 wt% of alpha-Al2O3Fine powder and 2-5 wt% of elemental silicon powder are taken as matrixes; firstly, uniformly mixing the aggregate in a stirrer, adding sulfite pulp waste liquid accounting for 3-7 wt% of the aggregate and the matrix, uniformly mixing, and thenAdding a matrix, stirring, forming, drying, heating to 1300-1500 ℃ under the condition of carbon burying, preserving heat, and cooling to obtain the SiC whisker reinforced corundum breathable refractory material. The product prepared by the invention has uniform ventilation, high strength, long service life, excellent thermal shock resistance and high molten steel inclusion removal efficiency.

Description

SiC whisker reinforced corundum breathable refractory material and preparation method thereof
Technical Field
The invention belongs to the technical field of corundum breathable refractory materials. In particular to a SiC whisker reinforced corundum breathable refractory material and a preparation method thereof.
Background
The inclusion is an important factor for limiting the quality improvement of high-quality steel and special steel. Inert gases such as argon and the like are blown into molten steel through the breathable refractory material, so that the process is an important process for homogenizing the temperature and the components of the molten steel and removing inclusions in the refining process, and has an important influence on the improvement of the steel quality.
Currently, studies on gas-permeable refractory materials have been reported. For example, the dispersive corundum air brick is prepared by a particle stacking method by using electric melting white corundum particles, Guangxi white mud and alumina micro powder as raw materials according to the literature technology (Jiagayang and the like, the influence of particle grading on the performance of the dispersive corundum air brick material, refractory material 2020, 54 (1): 32-36). The patent technology of 'sialon corundum refractory material for ladle gas plug and preparation method' (CN201410060767.X) adopts compact corundum particles, fine powder, silicon powder and alumina micropowder as raw materials and adopts a particle accumulation method to prepare the sialon corundum refractory material for the ladle gas plug. The breathable material prepared by the two technologies can only ventilate through pores among particles, and the pores are large and are not uniformly distributed, so that the ventilation uniformity is poor; meanwhile, firm neck connection is difficult to form among the particles, so that the product is low in strength and short in service life.
For another example, in the patent of "a corundum-based breathable refractory material and a preparation method thereof" (CN201811267698.8), corundum fine powder and aluminum hydroxide are used as raw materials, a porous granular material is prepared by a foaming method, and then dense corundum granules and the porous granular material are used as raw materials to prepare the corundum-based breathable refractory material. The porous particle material in the technology is prepared by a foaming method, the air holes are large, the blown air bubbles are large, the small impurities are not easy to be adsorbed, and furthermore, the blockage of the holes is easy to be caused when the ventilation is stopped; meanwhile, air cannot permeate the dense corundum particles, so that blown bubbles are not uniform.
For another example, in the patent technology of "an air brick for manufacturing a steel ladle and a manufacturing method thereof" (CN201810481355.5), the air brick for the steel ladle is manufactured by using a pore-forming agent method by using magnesium dolomite sand, manganese slag, aluminum hydroxide and nano activated clay as raw materials. The technology has the advantages of complex material composition, low eutectic point, easy formation of liquid phase at high temperature, influence on the stability and strength of a pore structure at high temperature, and short service life.
In summary, the existing gas-permeable refractory materials have some problems: (1) the neck connection between the particles is difficult to form, the strength is low, and the service life is short; (2) the compact aggregate cannot ventilate, pores are distributed unevenly, the size is large, and blown bubbles are large, so that the compact aggregate is not beneficial to adsorbing small-size impurities in molten steel; (3) the composition is complex, the eutectic point is low, and the high-temperature service performance is influenced by the generation of a liquid phase at high temperature.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a preparation method of a SiC whisker reinforced corundum breathable refractory material, and the SiC whisker reinforced corundum breathable refractory material prepared by the method has uniform ventilation, high strength, long service life, excellent thermal shock resistance and high molten steel inclusion removal efficiency.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
step 1, preparation of spherical porous corundum particles
Step 1.1, taking 93-98.5 wt% of fine aluminum hydroxide powder, 0.5-3 wt% of fine magnesia powder and 1-4 wt% of fine sawdust powder as raw materials, placing the raw materials into a mixer, and mixing for 1-3 hours; and adding a bonding agent accounting for 4-12 wt% of the raw materials into the mixer, and stirring for 10-20 minutes to obtain a mixture.
Step 1.2 preparation of three spherical blanks
Putting the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 4 revolutions per minute to prepare a spherical blank I with the particle size of 4.5 +/-0.3 mm;
putting the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotation speed of the granulator of 12 revolutions per minute to prepare a spherical blank II with the particle size of 1.8 +/-0.3 mm;
and (3) placing the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotation speed of the granulator of 18 revolutions per minute to obtain a spherical blank III with the particle size of 0.7 +/-0.2 mm.
Step 1.3, placing the spherical blank I into a rotary drying cylinder, and drying for 2-18 hours at the temperature of 110-130 ℃; heating to 300-350 ℃ at the speed of 2-4 ℃/min, preserving heat for 1-3 hours, heating to 1650-1750 ℃ at the speed of 5-8 ℃/min, preserving heat for 3-8 hours, and cooling along with the furnace to obtain the spherical porous corundum particles I.
The properties of the spherical porous corundum particles I are as follows: the apparent porosity is 33 to 43%; the bulk density is 2.22-2.68 g/cm3(ii) a The pore size distribution is bimodal, the large pore peak is 38-58 mu m, and the small pore peak is 4-14 mu m; the main crystal phase is corundum.
And (3) according to the preparation method of the step 1.3, respectively placing the spherical blank body II and the spherical blank body III into a rotary drying cylinder to prepare the corresponding spherical porous corundum particles II and the corresponding spherical porous corundum particles III.
The performance of the spherical porous corundum particles II and the performance of the spherical porous corundum particles III are the same as the performance of the spherical porous corundum particles I.
Step 2, preparation of modified spherical porous corundum particles
And 2.1, placing the deionized water and the catalyst into a stirrer according to the mass ratio of the deionized water to the catalyst of 100: 1.5-5.5, and stirring for 5-10 min to obtain a modified solution.
And 2.2, putting the spherical porous corundum particles I in a vacuum device according to the mass ratio of the spherical porous corundum particles I to the modification solution of 100 to (38-43), vacuumizing to 1.9-2.1 kPa, adding the modification solution, standing for 15-30 min, closing a vacuumizing system, and drying at 110-150 ℃ for 24-36 h to obtain the modified spherical porous corundum particles I.
And (3) according to the method in the step 2.2, respectively placing the spherical porous corundum particles II and the spherical porous corundum particles III in the modified solution to obtain corresponding modified spherical porous corundum particles II and modified spherical porous corundum particles III.
Step 3, preparing the SiC whisker reinforced corundum breathable refractory material
Taking 15-20 wt% of modified spherical porous corundum particles I, 31-39 wt% of modified spherical porous corundum particles II and 17-25 wt% of modified spherical porous corundum particles III as aggregates, 2-4 wt% of magnesia fine powder, 10-22 wt% of corundum fine powder and 3-6 wt% of alpha-Al2O3And taking the fine powder and 2-5 wt% of elemental silicon powder as matrixes.
Firstly, placing the aggregate in a stirrer, uniformly mixing, adding sulfurous acid pulp waste liquid accounting for 3-7 wt% of the aggregate and the matrix, uniformly mixing, adding the matrix, and uniformly stirring; and then pressing and forming under the condition of 110-150 MPa, drying for 18-36 hours at the temperature of 110 ℃, then heating to 1300-1500 ℃ at the speed of 3-7 ℃/min under the condition of carbon burying, preserving heat for 2-6 hours, and cooling to obtain the SiC whisker reinforced corundum breathable refractory material.
The grain size of the aluminum hydroxide fine powder is less than 0.088 mm; al of aluminum hydroxide fine powder2O3The content is more than 60 wt%.
The particle size of the fine sawdust powder is less than 75 mu m.
The binding agent is one of pulp waste liquid, polyvinyl alcohol and sodium carboxymethyl cellulose.
The catalyst is nickel nitrate fine powder or ferric nitrate fine powder; the particle size of the catalyst is less than 1 mu m.
The grain size of the corundum fine powder is less than 74 mu m; fine corundum powder Al2O3The content is more than 99 wt%.
The particle size of the elemental silicon powder is less than 50 mu m; the Si content of the elemental silicon powder is 98-99.5 wt%.
The particle size of the magnesite fine powder is less than 74 mu m; the MgO content of the magnesite fine powder is more than 96 wt%.
The alpha-Al2O3The grain size of the fine powder is less than 5 mu m; alpha-Al2O3Fine powder of Al2O3The content is more than 99 wt%.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following positive effects:
(1) the breathable refractory material prepared by adopting the modified spherical porous corundum particles has a multistage pore structure, small pore diameter, uniform ventilation and high molten steel inclusion removal efficiency.
The multi-stage air holes are formed in the breathable refractory material, and besides micron air holes generated by particle accumulation, two air holes also exist in the aggregate, wherein one air hole is a smaller micron air hole generated by in-situ decomposition of aluminum hydroxide and in-situ reaction with magnesia fine powder, and the other air hole is a larger micron air hole left by burning-out of wood chips; compared with the prior art, the 3 kinds of pores have smaller pore diameters, and realize the simultaneous ventilation of the aggregate and the matrix, and the pore distribution is more uniform. The air holes generated by particle accumulation and wood chip burning loss are relatively large and are main air-permeable channels; the pores generated by in-situ decomposition and synthesis are relatively small, and are mainly used for dispersing and distributing gas. The two functions are combined, so that when gas is introduced, bubbles are uniformly distributed on the whole interface of the breathable refractory material and the molten steel, the sizes of the bubbles are distributed in a multistage manner from small to large, the ventilation quantity and the ventilation uniformity are ensured, and the bubbles have higher removal efficiency on inclusions distributed in multiple sizes.
(2) The invention adopts a sawtooth-meshed interface structure, specially distributed silicon carbide whiskers and in-situ formed magnesium aluminate spinel for composite reinforcement, thereby greatly improving the strength and thermal shock stability of the breathable refractory material and prolonging the service life.
The surface of the modified spherical porous corundum particles has more micropores, so that the surface roughness of the aggregate is increased, and the contact area between the aggregate and the matrix is increased; on the one hand, when the aggregate is contacted with the substrate, the fine magnesite powder and the fine corundum powder, the fine magnesite powder and the alpha-Al powder are contained in the substrate2O3The fine powder reacts in situ to generate a small amount of magnesia-alumina spinel, thereby promoting neck connection and improving the strength of the neck; on the other hand, a sawtooth meshed interface structure is formed between the aggregate/aggregate and the aggregate/matrix, so that the aggregate/aggregate and the aggregate are greatly improvedBonding strength between substrates; meanwhile, due to the optimized material composition, the amount of liquid phase generated in a high-temperature service environment is very small, the high-temperature mechanical property is ensured, and the service life can be effectively prolonged.
Secondly, the modified spherical porous corundum particles not only have larger accommodating space, but also are internally attached with a catalyst, so that the silicon carbide whiskers can be formed inside and on the surfaces of the particles, and thus, the silicon carbide whiskers are formed inside the matrix and can also be formed inside the aggregate and on the interface between the aggregate and the matrix, the strength of the aggregate and the matrix can be improved, the defect of poor compatibility between the silicon carbide whiskers and the corundum interface in the existing material can be overcome, and the lock catch connection is formed between the aggregate/matrix and the aggregate/aggregate, so that the strength of the sawtooth-shaped occlusion interface is enhanced.
Therefore, the invention adopts a sawtooth-meshed interface structure, specially distributed silicon carbide whiskers and in-situ formed magnesium aluminate spinel for composite reinforcement, and greatly improves the strength and the thermal shock stability of the product.
(3) The modified spherical porous corundum aggregate prepared by the method has the advantages of single size, uniform component distribution, high utilization rate of raw materials and stable performance of the obtained product.
The spherical porous corundum aggregate is prepared by the granulation technology, the granularity and the appearance of the aggregate can be controlled, the resource utilization rate is high, the problem of uncontrollable granularity distribution caused by different production batches of the existing aggregate is solved, and the product has better structural and performance stability. Meanwhile, the spherical porous corundum particles are modified by adopting an impregnation process, so that the problem of uneven components caused by adding a catalyst in the later period is solved, and the silicon carbide whiskers can be more uniformly dispersed in the material.
The SiC whisker reinforced corundum breathable refractory material prepared by the invention comprises the following components in percentage by weight: the apparent porosity is 33 to 41%; the bulk density is 2.27g/cm3～2.68g/cm3(ii) a The pore size distribution is double peaks, the small pore peak is 13-23 μm, and the large pore peak is 38-78 μm; the compressive strength is 60-70 MPa.
Therefore, the whisker reinforced corundum breathable refractory material prepared by the invention has the characteristics of uniform ventilation, high strength, long service life, excellent thermal shock resistance and high molten steel inclusion removal efficiency.
Detailed Description
The invention is further described with reference to specific embodiments, without limiting its scope.
A SiC whisker reinforced corundum breathable refractory material and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step 1, preparation of spherical porous corundum particles
Step 1.1, taking 93-98.5 wt% of fine aluminum hydroxide powder, 0.5-3 wt% of fine magnesia powder and 1-4 wt% of fine sawdust powder as raw materials, placing the raw materials into a mixer, and mixing for 1-3 hours; and adding a bonding agent accounting for 4-12 wt% of the raw materials into the mixer, and stirring for 10-20 minutes to obtain a mixture.
Step 1.2 preparation of three spherical blanks
Putting the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 4 revolutions per minute to prepare a spherical blank I with the particle size of 4.5 +/-0.3 mm;
putting the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotation speed of the granulator of 12 revolutions per minute to prepare a spherical blank II with the particle size of 1.8 +/-0.3 mm;
and (3) placing the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotation speed of the granulator of 18 revolutions per minute to obtain a spherical blank III with the particle size of 0.7 +/-0.2 mm.
Step 1.3, placing the spherical blank I into a rotary drying cylinder, and drying for 2-18 hours at the temperature of 110-130 ℃; heating to 300-350 ℃ at the speed of 2-4 ℃/min, preserving heat for 1-3 hours, heating to 1650-1750 ℃ at the speed of 5-8 ℃/min, preserving heat for 3-8 hours, and cooling along with the furnace to obtain the spherical porous corundum particles I.
The properties of the spherical porous corundum particles I are as follows: the apparent porosity is 33 to 43%; the bulk density is 2.22-2.68 g/cm3(ii) a The pore size distribution is bimodal, the large pore peak is 38-58 mu m, and the small pore peak is4-14 μm; the main crystal phase is corundum.
And (3) according to the preparation method of the step 1.3, respectively placing the spherical blank body II and the spherical blank body III into a rotary drying cylinder to prepare the corresponding spherical porous corundum particles II and the corresponding spherical porous corundum particles III.
The performance of the spherical porous corundum particles II and the performance of the spherical porous corundum particles III are the same as the performance of the spherical porous corundum particles I.
Step 2, preparation of modified spherical porous corundum particles
And 2.1, placing the deionized water and the catalyst into a stirrer according to the mass ratio of the deionized water to the catalyst of 100: 1.5-5.5, and stirring for 5-10 min to obtain a modified solution.
And 2.2, putting the spherical porous corundum particles I in a vacuum device according to the mass ratio of the spherical porous corundum particles I to the modification solution of 100 to (38-43), vacuumizing to 1.9-2.1 kPa, adding the modification solution, standing for 15-30 min, closing a vacuumizing system, and drying at 110-150 ℃ for 24-36 h to obtain the modified spherical porous corundum particles I.
And (3) according to the method in the step 2.2, respectively placing the spherical porous corundum particles II and the spherical porous corundum particles III in the modified solution to obtain corresponding modified spherical porous corundum particles II and modified spherical porous corundum particles III.
Step 3, preparing the SiC whisker reinforced corundum breathable refractory material
Taking 15-20 wt% of modified spherical porous corundum particles I, 31-39 wt% of modified spherical porous corundum particles II and 17-25 wt% of modified spherical porous corundum particles III as aggregates, 2-4 wt% of magnesia fine powder, 10-22 wt% of corundum fine powder and 3-6 wt% of alpha-Al2O3And taking the fine powder and 2-5 wt% of elemental silicon powder as matrixes.
Firstly, placing the aggregate in a stirrer, uniformly mixing, adding sulfurous acid pulp waste liquid accounting for 3-7 wt% of the aggregate and the matrix, uniformly mixing, adding the matrix, and uniformly stirring; and then pressing and forming under the condition of 110-150 MPa, drying for 18-36 hours at the temperature of 110 ℃, then heating to 1300-1500 ℃ at the speed of 3-7 ℃/min under the condition of carbon burying, preserving heat for 2-6 hours, and cooling to obtain the SiC whisker reinforced corundum breathable refractory material.
Al of aluminum hydroxide fine powder2O3The content is more than 60 wt%.
The binding agent is one of pulp waste liquid, polyvinyl alcohol and sodium carboxymethyl cellulose.
The catalyst is nickel nitrate fine powder or ferric nitrate fine powder.
Fine corundum powder Al2O3The content is more than 99 wt%.
The Si content of the elemental silicon powder is 98-99.5 wt%.
The MgO content of the magnesite fine powder is more than 96 wt%.
α-Al2O3Fine powder of Al2O3The content is more than 99 wt%.
In this embodiment:
the grain size of the aluminum hydroxide fine powder is less than 0.088 mm;
the particle size of the wood chip fine powder is less than 75 mu m;
the particle size of the catalyst is less than 1 mu m;
the grain size of the corundum fine powder is less than 74 mu m;
the particle size of the elemental silicon powder is less than 50 mu m;
the particle size of the magnesite fine powder is less than 74 mu m;
the alpha-Al2O3The particle size of the fine powder is less than 5 mu m.
The detailed description is omitted in the embodiments.
Example 1
A SiC whisker reinforced corundum breathable refractory material and a preparation method thereof. The preparation method in this example is:
step 1, preparation of spherical porous corundum particles
Step 1.1, taking 93 wt% of fine aluminum hydroxide powder, 3 wt% of fine magnesia powder and 4 wt% of fine sawdust powder as raw materials, placing the raw materials into a mixer, and mixing for 1.0 hour; and adding a bonding agent accounting for 4 wt% of the raw materials into the mixer, and stirring for 20 minutes to obtain a mixture.
Step 1.2 preparation of three spherical blanks
Putting the mixture into a granulator, adding 8 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 4 revolutions per minute to prepare a spherical blank I with the particle size of 4.5 +/-0.3 mm;
putting the mixture into a granulator, adding 8 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 12 revolutions per minute to prepare a spherical blank II with the particle size of 1.8 +/-0.3 mm;
and (3) putting the mixture into a granulator, adding 8 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 18 revolutions per minute to obtain a spherical blank III with the particle size of 0.7 +/-0.2 mm.
Step 1.3, placing the spherical blank I into a rotary drying cylinder, and drying for 2 hours at the temperature of 130 ℃; heating to 300 ℃ at the speed of 4 ℃/min, preserving heat for 1 hour, heating to 1650 ℃ at the speed of 5 ℃/min, preserving heat for 8 hours, and cooling along with the furnace to obtain the spherical porous corundum particles I.
The properties of the spherical porous corundum particles I are as follows: the apparent porosity is 43%; the bulk density is 2.22g/cm3(ii) a The pore size distribution is double peaks, the big pore peak is 58 mu m, and the small pore peak is 14 mu m; the main crystal phase is corundum.
And (3) according to the preparation method of the step 1.3, respectively placing the spherical blank body II and the spherical blank body III into a rotary drying cylinder to prepare the corresponding spherical porous corundum particles II and the corresponding spherical porous corundum particles III.
The performance of the spherical porous corundum particles II and the performance of the spherical porous corundum particles III are the same as the performance of the spherical porous corundum particles I.
Step 2, preparation of modified spherical porous corundum particles
And 2.1, placing the deionized water and the catalyst in a stirrer according to the mass ratio of the deionized water to the catalyst of 100: 1.5, and stirring for 5min to obtain a modified solution.
And 2.2, putting the spherical porous corundum particles I into a vacuum device according to the mass ratio of the spherical porous corundum particles I to the modification solution of 100: 38, vacuumizing to 1.9kPa, adding the modification solution, standing for 15min, closing a vacuumizing system, and drying at 110 ℃ for 24h to obtain the modified spherical porous corundum particles I.
And (3) according to the method in the step 2.2, respectively placing the spherical porous corundum particles II and the spherical porous corundum particles III in the modified solution to obtain corresponding modified spherical porous corundum particles II and modified spherical porous corundum particles III.
Step 3, preparing the SiC whisker reinforced corundum breathable refractory material
Taking 15 wt% of modified spherical porous corundum particles I, 31 wt% of modified spherical porous corundum particles II and 17 wt% of modified spherical porous corundum particles III as aggregate, 4 wt% of magnesia fine powder, 22 wt% of corundum fine powder and 6 wt% of alpha-Al2O3Fine powder and 5 wt% of simple substance silicon powder are taken as matrix.
Firstly, placing the aggregate in a stirrer, uniformly mixing, adding sulfurous acid pulp waste liquid accounting for 3 wt% of the aggregate and the matrix, uniformly mixing, adding the matrix, and uniformly stirring; then pressing and molding under the condition of 110MPa, drying for 18 hours under the condition of 110 ℃, then heating to 1300 ℃ at the speed of 3 ℃/min under the condition of carbon embedding, preserving heat for 2 hours, and cooling to obtain the SiC whisker reinforced corundum breathable refractory material.
Al of aluminum hydroxide fine powder2O3The content was 63.25 wt%.
The binding agent is polyvinyl alcohol.
The catalyst is nickel nitrate fine powder.
Fine corundum powder Al2O3The content was 99.02 wt%.
The Si content of the elemental silicon powder is 98.11 wt%.
The MgO content of the fine magnesia powder was 96.14 wt%.
α-Al2O3Fine powder of Al2O3The content was 99.21 wt%.
The SiC whisker reinforced corundum gas-permeable refractory material prepared in this example:the apparent porosity is 33%; the bulk density is 2.66g/cm3(ii) a The pore size distribution is double peaks, the small pore peak is 13 μm, and the large pore peak is 38 μm; the compressive strength was 66 MPa.
Example 2
A SiC whisker reinforced corundum breathable refractory material and a preparation method thereof. The preparation method in this example is:
step 1, preparation of spherical porous corundum particles
Step 1.1, taking 94.5 wt% of aluminum hydroxide fine powder, 2.3 wt% of magnesia fine powder and 3.2 wt% of wood chip fine powder as raw materials, putting the raw materials into a mixer, and mixing for 2.5 hours; and adding a bonding agent accounting for 6 wt% of the raw materials into the mixer, and stirring for 17 minutes to obtain a mixture.
Step 1.2 preparation of three spherical blanks
Putting the mixture into a granulator, adding 6 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 4 revolutions per minute to prepare a spherical blank I with the particle size of 4.5 +/-0.3 mm;
putting the mixture into a granulator, adding 6 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 12 revolutions per minute to prepare a spherical blank II with the particle size of 1.8 +/-0.3 mm;
and (3) placing the mixture into a granulator, adding 6 wt% of water into the mixture, and spraying at the rotation speed of the granulator of 18 revolutions per minute to obtain a spherical blank III with the particle size of 0.7 +/-0.2 mm.
Step 1.3, placing the spherical blank I into a rotary drying cylinder, and drying for 7 hours at the temperature of 120 ℃; heating to 320 ℃ at the speed of 3 ℃/min, preserving heat for 2 hours, heating to 1680 ℃ at the speed of 6 ℃/min, preserving heat for 6 hours, and cooling along with the furnace to obtain the spherical porous corundum particles I.
The properties of the spherical porous corundum particles I are as follows: the apparent porosity is 40.02%; the bulk density is 2.37g/cm3(ii) a The pore size distribution is double peaks, the big pore peak is 54.12 μm, and the small pore peak is 10.31 μm; the main crystal phase is corundum.
And (3) according to the preparation method of the step 1.3, respectively placing the spherical blank body II and the spherical blank body III into a rotary drying cylinder to prepare the corresponding spherical porous corundum particles II and the corresponding spherical porous corundum particles III.
The performance of the spherical porous corundum particles II and the performance of the spherical porous corundum particles III are the same as the performance of the spherical porous corundum particles I.
Step 2, preparation of modified spherical porous corundum particles
And 2.1, placing the deionized water and the catalyst in a stirrer according to the mass ratio of the deionized water to the catalyst of 100: 2.5, and stirring for 7.5min to obtain a modified solution.
And 2.2, putting the spherical porous corundum particles I into a vacuum device according to the mass ratio of the spherical porous corundum particles I to the modification solution of 100: 40, vacuumizing to 1.95kPa, adding the modification solution, standing for 20min, closing a vacuumizing system, and drying at 120 ℃ for 28h to obtain the modified spherical porous corundum particles I.
And (3) according to the method in the step 2.2, respectively placing the spherical porous corundum particles II and the spherical porous corundum particles III in the modified solution to obtain corresponding modified spherical porous corundum particles II and modified spherical porous corundum particles III.
Step 3, preparing the SiC whisker reinforced corundum breathable refractory material
16 wt% of modified spherical porous corundum particles I, 36 wt% of modified spherical porous corundum particles II and 19 wt% of modified spherical porous corundum particles III are used as aggregate, 3 wt% of magnesia fine powder, 19 wt% of corundum fine powder and 4 wt% of alpha-Al2O3Fine powder and 3 wt% of simple substance silicon powder are taken as matrix.
Firstly, placing the aggregate in a stirrer, uniformly mixing, adding sulfurous acid pulp waste liquid accounting for 4 wt% of the aggregate and the matrix, uniformly mixing, adding the matrix, and uniformly stirring; then pressing and molding under the condition of 125MPa, drying for 24 hours at the temperature of 110 ℃, then heating to 1380 ℃ at the speed of 4 ℃/min under the condition of carbon embedding, preserving heat for 4 hours, and cooling to obtain the SiC whisker reinforced corundum breathable refractory material.
Al of aluminum hydroxide fine powder2O3The content was 64.86 wt%.
The binding agent is polyvinyl alcohol.
The catalyst is nickel nitrate fine powder.
Fine corundum powder Al2O3The content was 99.24 wt%.
The Si content of the elemental silicon powder is 98.56 wt%.
The MgO content of the fine magnesia powder was 96.53 wt%.
α-Al2O3Fine powder of Al2O3The content was 99.46 wt%.
The SiC whisker reinforced corundum gas-permeable refractory material prepared in this example: the apparent porosity is 36.05%; the bulk density is 2.54g/cm3(ii) a The pore size distribution is double peaks, the small pore peak is 17.21 μm, and the large pore peak is 55.14 μm; the compressive strength was 63.2 MPa.
Example 3
A SiC whisker reinforced corundum breathable refractory material and a preparation method thereof. The preparation method in this example is:
step 1, preparation of spherical porous corundum particles
Step 1.1, taking 96.5 wt% of aluminum hydroxide fine powder, 1.4 wt% of magnesia fine powder and 2.1 wt% of wood chip fine powder as raw materials, putting the raw materials into a mixer, and mixing for 2 hours; and adding a bonding agent accounting for 10 wt% of the raw materials into the mixer, and stirring for 13 minutes to obtain a mixture.
Step 1.2 preparation of three spherical blanks
Putting the mixture into a granulator, adding 4 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 4 revolutions per minute to prepare a spherical blank I with the particle size of 4.5 +/-0.3 mm;
putting the mixture into a granulator, adding 4 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 12 revolutions per minute to prepare a spherical blank II with the particle size of 1.8 +/-0.3 mm;
and (3) putting the mixture into a granulator, adding 4 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 18 revolutions per minute to obtain a spherical blank III with the particle size of 0.7 +/-0.2 mm.
Step 1.3, placing the spherical blank I into a rotary drying cylinder, and drying for 12 hours at the temperature of 110 ℃; heating to 340 ℃ at the speed of 2 ℃/min, preserving heat for 2 hours, heating to 1720 ℃ at the speed of 7 ℃/min, preserving heat for 4 hours, and cooling along with the furnace to obtain the spherical porous corundum particles I.
The properties of the spherical porous corundum particles I are as follows: the apparent porosity is 36.15%; the bulk density is 2.54g/cm3(ii) a The pore size distribution is double peaks, wherein a large pore peak is 47.23 mu m, and a small pore peak is 7.52 mu m; the main crystal phase is corundum.
And (3) according to the preparation method of the step 1.3, respectively placing the spherical blank body II and the spherical blank body III into a rotary drying cylinder to prepare the corresponding spherical porous corundum particles II and the corresponding spherical porous corundum particles III.
The performance of the spherical porous corundum particles II and the performance of the spherical porous corundum particles III are the same as the performance of the spherical porous corundum particles I.
Step 2, preparation of modified spherical porous corundum particles
And 2.1, placing the deionized water and the catalyst in a stirrer according to the mass ratio of the deionized water to the catalyst of 100: 3.5, and stirring for 8.5min to obtain a modified solution.
And 2.2, putting the spherical porous corundum particles I into a vacuum device according to the mass ratio of the spherical porous corundum particles I to the modification solution of 100: 42, vacuumizing to 2.05kPa, adding the modification solution, standing for 25min, closing a vacuumizing system, and drying at 135 ℃ for 32h to obtain the modified spherical porous corundum particles I.
And (3) according to the method in the step 2.2, respectively placing the spherical porous corundum particles II and the spherical porous corundum particles III in the modified solution to obtain corresponding modified spherical porous corundum particles II and modified spherical porous corundum particles III.
Step 3, preparing the SiC whisker reinforced corundum breathable refractory material
18 wt% of modified spherical porous corundum particles I, 34 wt% of modified spherical porous corundum particles II and 22.5The modified spherical porous corundum particles III are used as aggregate in percentage by weight, and 2.5 percent of magnesia fine powder, 14 percent of corundum fine powder and 5 percent of alpha-Al in percentage by weight are used2O3Fine powder and 4 wt% of simple substance silicon powder are taken as matrix.
Firstly, placing the aggregate in a stirrer, uniformly mixing, adding sulfurous acid pulp waste liquid accounting for 5 wt% of the aggregate and the matrix, uniformly mixing, adding the matrix, and uniformly stirring; then pressing and molding under the condition of 140MPa, drying for 30 hours under the condition of 110 ℃, then heating to 1460 ℃ at the speed of 6 ℃/min under the condition of carbon embedding, preserving heat for 5 hours, and cooling to obtain the SiC whisker reinforced corundum breathable refractory material.
Al of aluminum hydroxide fine powder2O3The content was 65.23 wt%.
The binding agent is sodium carboxymethyl cellulose.
The catalyst is ferric nitrate fine powder.
Fine corundum powder Al2O3The content was 99.47 wt%.
The Si content of the elemental silicon powder is 99.03 wt%.
The MgO content of the magnesite fine powder is 97.29%.
α-Al2O3Fine powder of Al2O3The content was 99.69 wt%.
The SiC whisker reinforced corundum gas-permeable refractory material prepared in this example: the apparent porosity is 38.12%; the bulk density is 2.45g/cm3(ii) a The pore size distribution is double peaks, the small pore peak is 20.03 mu m, and the large pore peak is 70.46 mu m; the compressive strength was 60.4 MPa.
Example 4
A SiC whisker reinforced corundum breathable refractory material and a preparation method thereof. The preparation method in this example is:
step 1, preparation of spherical porous corundum particles
Step 1.1, taking 98.5 wt% of fine aluminum hydroxide powder, 0.5 wt% of fine magnesia powder and 1 wt% of fine sawdust powder as raw materials, putting the raw materials into a mixer, and mixing for 3 hours; and adding a bonding agent accounting for 12 wt% of the raw materials into the mixer, and stirring for 10 minutes to obtain a mixture.
Step 1.2 preparation of three spherical blanks
Putting the mixture into a granulator, adding 2 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 4 revolutions per minute to prepare a spherical blank I with the particle size of 4.5 +/-0.3 mm;
putting the mixture into a granulator, adding 2 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 12 revolutions per minute to prepare a spherical blank II with the particle size of 1.8 +/-0.3 mm;
and (3) placing the mixture into a granulator, adding 2 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 18 revolutions per minute to obtain a spherical blank III with the particle size of 0.7 +/-0.2 mm.
Step 1.3, placing the spherical blank I into a rotary drying cylinder, and drying for 18 hours at the temperature of 110 ℃; heating to 350 ℃ at the speed of 2 ℃/min, preserving heat for 3 hours, heating to 1750 ℃ at the speed of 8 ℃/min, preserving heat for 3 hours, and cooling along with the furnace to obtain the spherical porous corundum particles I.
The properties of the spherical porous corundum particles I are as follows: the apparent porosity is 33%; the bulk density is 2.68g/cm3(ii) a The pore size distribution is bimodal, the large pore peak is 38 μm, and the small pore peak is 4 μm; the main crystal phase is corundum.
And (3) according to the preparation method of the step 1.3, respectively placing the spherical blank body II and the spherical blank body III into a rotary drying cylinder to prepare the corresponding spherical porous corundum particles II and the corresponding spherical porous corundum particles III.
The performance of the spherical porous corundum particles II and the performance of the spherical porous corundum particles III are the same as the performance of the spherical porous corundum particles I.
Step 2, preparation of modified spherical porous corundum particles
And 2.1, placing the deionized water and the catalyst in a stirrer according to the mass ratio of the deionized water to the catalyst of 100: 5.5, and stirring for 10min to obtain a modified solution.
And 2.2, putting the spherical porous corundum particles I into a vacuum device according to the mass ratio of the spherical porous corundum particles I to the modification solution of 100: 43, vacuumizing to 2.1kPa, adding the modification solution, standing for 30min, closing a vacuumizing system, and drying at 150 ℃ for 36h to obtain the modified spherical porous corundum particles I.
And (3) according to the method in the step 2.2, respectively placing the spherical porous corundum particles II and the spherical porous corundum particles III in the modified solution to obtain corresponding modified spherical porous corundum particles II and modified spherical porous corundum particles III.
Step 3, preparing the SiC whisker reinforced corundum breathable refractory material
19.7 weight percent of modified spherical porous corundum particle I, 38.6 weight percent of modified spherical porous corundum particle II and 24.7 weight percent of modified spherical porous corundum particle III are taken as aggregate, 2 weight percent of magnesia fine powder, 10 weight percent of corundum fine powder and 3 weight percent of alpha-Al2O3Fine powder and 2 wt% of simple substance silicon powder are taken as matrix.
Firstly, placing the aggregate in a stirrer, uniformly mixing, adding sulfurous acid pulp waste liquid accounting for 7 wt% of the aggregate and the matrix, uniformly mixing, adding the matrix, and uniformly stirring; then pressing and molding under the condition of 150MPa, drying for 36 hours under the condition of 110 ℃, then heating to 1500 ℃ at the speed of 7 ℃/min under the condition of carbon embedding, preserving heat for 6 hours, and cooling to obtain the SiC whisker reinforced corundum breathable refractory material.
Al of aluminum hydroxide fine powder2O3The content was 66.07 wt%.
The binding agent is paper pulp waste liquid.
The catalyst is ferric nitrate fine powder.
Fine corundum powder Al2O3The content was 99.63 wt%.
The Si content of the elemental silicon powder is 99.48 wt%.
MgO content% of the fine magnesia powder.
α-Al2O3Fine powder of Al2O3The content is more than 97 wt%.
The SiC whisker reinforced corundum gas-permeable refractory material prepared in this example: the apparent porosity is 40.6%; the bulk density is 2.28g/cm3(ii) a The pore size distribution is double peaks, the small pore peak is 22 μm, and the large pore peak is 76 μm; the compressive strength was 69 MPa.
Compared with the prior art, the specific implementation mode has the following positive effects:
(1) the permeable refractory material prepared by the modified spherical porous corundum particles has a multistage pore structure, small pore diameter, uniform permeability and high molten steel inclusion removal efficiency.
The multi-stage pores exist in the breathable refractory material of the embodiment, and besides the micron pores generated by particle accumulation, two pores also exist in the aggregate, wherein one pore is a smaller micron pore generated by in-situ decomposition of aluminum hydroxide and in-situ reaction with fine magnesia powder, and the other pore is a larger micron pore left by wood chips after loss of fire; compared with the prior art, the 3 kinds of pores have smaller pore diameters, and realize the simultaneous ventilation of the aggregate and the matrix, and the pore distribution is more uniform. The air holes generated by particle accumulation and wood chip burning loss are relatively large and are main air-permeable channels; the pores generated by in-situ decomposition and synthesis are relatively small, and are mainly used for dispersing and distributing gas. The two functions are combined, so that when gas is introduced, bubbles are uniformly distributed on the whole interface of the breathable refractory material and the molten steel, the sizes of the bubbles are distributed in a multistage manner from small to large, the ventilation quantity and the ventilation uniformity are ensured, and the bubbles have higher removal efficiency on inclusions distributed in multiple sizes.
(2) According to the specific embodiment, the sawtooth-meshed interface structure, the specially-distributed silicon carbide whiskers and the in-situ formed magnesium aluminate spinel are compositely enhanced, so that the strength and the thermal shock stability of the breathable refractory material are greatly improved, and the service life of the breathable refractory material is prolonged.
The surface of the modified spherical porous corundum particles has more micropores, so that the surface roughness of the aggregate is increased, and the contact area between the aggregate and the matrix is increased; on the one hand, when the aggregate is contacted with the substrate, the fine magnesite powder and the fine corundum powder, the fine magnesite powder and the alpha-Al powder are contained in the substrate2O3The fine powder reacts in situ to generate a small amount of magnesia-alumina spinel, thereby promoting neck connection and improving the strength of the neck; on the other hand, forming the saw between aggregate/aggregate and aggregate/matrixThe tooth-meshed interface structure greatly improves the bonding strength between the aggregate/aggregate and the aggregate/matrix and can effectively prolong the service life.
Secondly, the modified spherical porous corundum particles not only have larger accommodating space, but also are internally attached with a catalyst, so that the silicon carbide whiskers can be formed inside and on the surfaces of the particles, and thus, the silicon carbide whiskers are formed inside the matrix and can also be formed inside the aggregate and on the interface between the aggregate and the matrix, the strength of the aggregate and the matrix can be improved, the defect of poor compatibility between the silicon carbide whiskers and the corundum interface in the existing material can be overcome, and the lock catch connection is formed between the aggregate/matrix and the aggregate/aggregate, so that the strength of the sawtooth-shaped occlusion interface is enhanced.
Therefore, the specific embodiment adopts a sawtooth-meshed interface structure, specially distributed silicon carbide whiskers and in-situ formed magnesium aluminate spinel for composite reinforcement, so that the strength and the thermal shock stability of the product are greatly improved.
(3) The modified spherical porous corundum aggregate prepared by the specific embodiment has the advantages of single size, uniform component distribution, high utilization rate of raw materials and stable performance of the obtained product.
This embodiment prepares spherical porous corundum aggregate through granulation technique, and the granularity and the appearance of aggregate can be controlled, and resource utilization is high, avoids current aggregate to cause the uncontrollable problem of particle size distribution because of different production batch problems for the goods have better structure and performance stability. Meanwhile, the spherical porous corundum particles are modified by adopting an impregnation process, so that the problem of uneven components caused by adding a catalyst in the later period is solved, and the silicon carbide whiskers can be more uniformly dispersed in the material.
The SiC whisker reinforced corundum breathable refractory material prepared by the specific embodiment comprises the following components in percentage by weight: the apparent porosity is 33 to 41%; the bulk density is 2.27g/cm3～2.68g/cm3(ii) a The pore size distribution is double peaks, the small pore peak is 13-23 μm, and the large pore peak is 38-78 μm; the compressive strength is 60-70 MPa.
Therefore, the whisker reinforced corundum breathable refractory material prepared by the embodiment has the characteristics of uniform ventilation, high strength, long service life, excellent thermal shock resistance and high molten steel inclusion removal efficiency.

Claims (10)

1. A preparation method of a SiC whisker reinforced corundum breathable refractory material is characterized by comprising the following steps:
step 1, preparation of spherical porous corundum particles
Step 1.1, taking 93-98.5 wt% of fine aluminum hydroxide powder, 0.5-3 wt% of fine magnesia powder and 1-4 wt% of fine sawdust powder as raw materials, placing the raw materials into a mixer, and mixing for 1-3 hours; adding a bonding agent accounting for 4-12 wt% of the raw materials into the mixer, and stirring for 10-20 minutes to obtain a mixture;
step 1.2 preparation of three spherical blanks
Putting the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 4 revolutions per minute to prepare a spherical blank I with the particle size of 4.5 +/-0.3 mm;
putting the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotation speed of the granulator of 12 revolutions per minute to prepare a spherical blank II with the particle size of 1.8 +/-0.3 mm;
putting the mixture into a granulator, adding 2-8 wt% of water into the mixture, and spraying at the rotating speed of the granulator of 18 revolutions per minute to obtain a spherical blank III with the particle size of 0.7 +/-0.2 mm;
step 1.3, placing the spherical blank I into a rotary drying cylinder, and drying for 2-18 hours at the temperature of 110-130 ℃; heating to 300-350 ℃ at the speed of 2-4 ℃/min, preserving heat for 1-3 hours, heating to 1650-1750 ℃ at the speed of 5-8 ℃/min, preserving heat for 3-8 hours, and cooling along with the furnace to obtain spherical porous corundum particles I;
the properties of the spherical porous corundum particles I are as follows: the apparent porosity is 33 to 43%; the bulk density is 2.22-2.68 g/cm3(ii) a The pore size distribution is bimodal, the large pore peak is 38-58 mu m, and the small pore peak is 4-14 mu m; the main crystal phase is corundum;
according to the preparation method of the step 1.3, respectively placing the spherical blank body II and the spherical blank body III into a rotary drying cylinder to prepare corresponding spherical porous corundum particles II and spherical porous corundum particles III;
the performance of the spherical porous corundum particles II and the performance of the spherical porous corundum particles III are the same as the performance of the spherical porous corundum particles I;
step 2, preparation of modified spherical porous corundum particles
Step 2.1, placing the deionized water and the catalyst into a stirrer according to the mass ratio of the deionized water to the catalyst of 100: 1.5-5.5, and stirring for 5-10 min to obtain a modified solution;
step 2.2, placing the spherical porous corundum particles I in a vacuum device according to the mass ratio of the spherical porous corundum particles I to the modification solution of 100 to (38-43), vacuumizing to 1.9-2.1 kPa, adding the modification solution, standing for 15-30 min, closing a vacuumizing system, and drying at 110-150 ℃ for 24-36 h to obtain the modified spherical porous corundum particles I;
according to the method in the step 2.2, respectively placing the spherical porous corundum particles II and the spherical porous corundum particles III in the modified solution to obtain corresponding modified spherical porous corundum particles II and modified spherical porous corundum particles III;
step 3, preparing the SiC whisker reinforced corundum breathable refractory material
Taking 15-20 wt% of modified spherical porous corundum particles I, 31-39 wt% of modified spherical porous corundum particles II and 17-25 wt% of modified spherical porous corundum particles III as aggregates, 2-4 wt% of magnesia fine powder, 10-22 wt% of corundum fine powder and 3-6 wt% of alpha-Al2O3Fine powder and 2-5 wt% of elemental silicon powder are taken as matrixes;
firstly, placing the aggregate in a stirrer, uniformly mixing, adding sulfurous acid pulp waste liquid accounting for 3-7 wt% of the aggregate and the matrix, uniformly mixing, adding the matrix, and uniformly stirring; and then pressing and forming under the condition of 110-150 MPa, drying for 18-36 hours at the temperature of 110 ℃, then heating to 1300-1500 ℃ at the speed of 3-7 ℃/min under the condition of carbon burying, preserving heat for 2-6 hours, and cooling to obtain the SiC whisker reinforced corundum breathable refractory material.
2. The method for preparing the SiC whisker reinforced corundum breathable refractory material according to claim 1, characterized in that the grain size of the aluminum hydroxide fine powder is less than 0.088 mm; al of aluminum hydroxide fine powder2O3The content is more than 60 wt%.
3. The method of claim 1, wherein the fine powder of wood chips has a particle size of less than 75 μm.
4. The method for preparing the SiC whisker reinforced corundum breathable refractory material according to claim 1, characterized in that the bonding agent is one of pulp waste liquor, polyvinyl alcohol and sodium carboxymethylcellulose.
5. The method for preparing the SiC whisker reinforced corundum breathable refractory material according to claim 1, characterized in that the catalyst is nickel nitrate fine powder or ferric nitrate fine powder; the particle size of the catalyst is less than 1 mu m.
6. The method for preparing the SiC whisker reinforced corundum gas-permeable refractory material according to claim 1, characterized in that the corundum fine powder has a particle size of < 74 μm; fine corundum powder Al2O3The content is more than 99 wt%.
7. The preparation method of the SiC whisker reinforced corundum breathable refractory material according to claim 1, characterized in that the particle size of the elemental silicon powder is less than 50 μm; the Si content of the elemental silicon powder is 98-99.5 wt%.
8. The method for preparing the SiC whisker reinforced corundum gas-permeable refractory material according to claim 1, characterized in that the particle size of the magnesite powder is less than 74 μm; the MgO content of the magnesite fine powder is more than 96 wt%.
9. According to the rightThe method for preparing SiC whisker reinforced corundum gas-permeable refractory material according to claim 1, characterized in that the α -Al is2O3The grain size of the fine powder is less than 5 mu m; alpha-Al2O3Fine powder of Al2O3The content is more than 99 wt%.
10. A SiC whisker reinforced corundum gas-permeable refractory material, characterized in that the SiC whisker reinforced corundum gas-permeable refractory material is a SiC whisker reinforced corundum gas-permeable refractory material according to the method for preparing a SiC whisker reinforced corundum gas-permeable refractory material according to any one of claims 1 to 9.
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