Anti-erosion gas permeable brick and its preparation process

Abstract

The present application relates to the technical field of gas permeable brick, and particularly relates to an anti-erosion gas permeable brick and a preparation process thereof, which comprises the following components: fused magnesia particles, flaky graphite, modified zirconia fine powder, metallic aluminum fine powder, boron carbide fine powder and phenolic resin. The present application builds a composite coating layer on the surface of zirconia by modifying titanate and modifying boric acid, generates a dense titanium dioxide layer in situ by titanium components at high temperature to block the erosion of calcium oxide in slag, and at the same time, the boron component forms a high-melting-point phase to fill the grain boundary pores, so as to inhibit the penetration of molten slag and the precipitation of harmful dendrites, thereby improving the structural stability and slag erosion resistance of the gas permeable brick.

Description

Technical Field

[0001] This invention belongs to the field of breathable brick technology, specifically an anti-erosion breathable brick and its preparation process. Background Technology

[0002] Permeable bricks are a key component in bottom-blown argon gas refining, and zirconia is often used on the working face to enhance thermal shock and erosion resistance. However, when using high-basicity refining slag, zirconia suffers severe chemical corrosion. At high temperatures, high-calcium oxide slag penetrates the reaction layer, causing the stabilizers in the zirconia grains to desolve into the slag, destabilizing the zirconia and transforming it from a tetragonal phase to a monoclinic phase. Simultaneously, calcium oxide and silica in the slag react with zirconia to form low-melting-point calcium zirconium silicates, causing the zirconia particles to dissolve and destroying the dense structure of the reaction layer.

[0003] Zr produced by the reaction of zirconium oxide with slag 4+ Ca 2+ Si 4+ Plasma enters the slag phase and migrates to the outside of the reaction layer driven by temperature or concentration gradients. When local supersaturation occurs, dendritic zirconium-containing silicate phases precipitate. These precipitates have weak adhesion to the matrix and induce local stress, leading to a loose structure and microcracks on the outside of the reaction layer. Under the scouring of molten steel, the loose layer is easily peeled off, exposing fresh interfaces and accelerating corrosion. This negative feedback loop ultimately leads to grain shedding and structural loosening of the working surface, significantly shortening its service life. Summary of the Invention

[0004] (1) Technical problems to be solved:

[0005] The purpose of this invention is to provide an anti-erosion permeable brick and its preparation process to solve the problem of chemical corrosion of zirconium oxide by high-alkalinity slag and the secondary dendrite re-precipitation induced by it, thereby destroying the dense continuity of the reaction layer.

[0006] (2) Technical solution:

[0007] To achieve the above objectives, on the one hand, the present invention provides an anti-erosion breathable brick, comprising the following components in parts by weight: 80-85 parts of fused magnesia particles, 10-12 parts of flake graphite, 3-5 parts of modified zirconium oxide fine powder, 2-3 parts of metallic aluminum fine powder, 1-2 parts of boron carbide fine powder, and 3-4 parts of phenolic resin.

[0008] The particle size of the fused magnesia particles includes 3-5mm, 1-3mm and 0-1mm sizes; the mass ratio of the 3-5mm fused magnesia particles, the 1-3mm fused magnesia particles and the 0-1mm fused magnesia particles is 3:3:4.

[0009] The modified zirconium oxide is a composite obtained by coating zirconium oxide with modified tetrabutyl titanate and modified boric acid and then heat-treating it; the modified tetrabutyl titanate is tetrabutyl titanate organically chelated with acetylacetone; the modified boric acid is boric acid organically esterified with N-methyliminodiacetic acid.

[0010] Furthermore, the preparation method of the modified tetrabutyl titanate includes the following steps:

[0011] S11. Under nitrogen protection, tetrabutyl titanate is dissolved in anhydrous ethanol to obtain an ethanol solution of tetrabutyl titanate; acetylacetone is mixed with anhydrous ethanol to obtain an ethanol solution of acetylacetone.

[0012] S12. Under stirring, the ethanol solution of acetylacetone is added dropwise to the ethanol solution of tetrabutyl titanate; after the addition is complete, the temperature is raised to 60°C to react and a mixed solution A is obtained; the solvent is removed by rotary evaporation of mixed solution A to obtain modified tetrabutyl titanate, which is then sealed and stored.

[0013] Furthermore, the molar ratio of the tetrabutyl titanate to the acetylacetone is 1:1.2.

[0014] Furthermore, the preparation method of the modified boric acid includes the following steps:

[0015] S21. Add boric acid, N-methyliminodiacetic acid, dimethyl sulfoxide, toluene and p-toluenesulfonic acid to the reaction flask in sequence, heat to 110-120℃ and reflux to separate water until no water is generated, to obtain mixed solution B;

[0016] S22. After cooling the mixed solution B, slowly pour it into diethyl ether under cooling to precipitate; let it stand to allow the precipitation to be complete, filter it, and wash the filter cake A with diethyl ether at 0-5℃ to obtain the crude product;

[0017] S23. Transfer the crude product to a round-bottom flask, add acetone at 50-60℃ and stir. If the solid is not completely dissolved, add more acetone at 50-60℃ until the solid is completely dissolved. Filter while hot (the funnel needs to be preheated). After the filtrate cools naturally to room temperature, place it in 0-5℃ to cool and crystallize. Filter by suction, and wash filter cake B with acetone at 0-5℃. Place filter cake B in a vacuum drying oven to dry and obtain modified boric acid.

[0018] Furthermore, the preparation method of the modified zirconium oxide fine powder includes the following steps:

[0019] S1. Weigh monoclinic zirconium oxide powder, place it in a three-necked flask, add anhydrous ethanol, and ultrasonically disperse it to fully disperse the powder and obtain a suspension;

[0020] S2. Weigh out the modified tetrabutyl titanate and dissolve it in anhydrous ethanol to obtain the first mixed solution; transfer the first mixed solution into a constant pressure dropping funnel and add it dropwise into the suspension while stirring; after the addition is complete, raise the temperature to 60°C and stir the reaction at a constant temperature to obtain the active intermediate suspension.

[0021] S3. Weigh the modified boric acid and dissolve it in anhydrous ethanol to obtain a second mixed solution; add the second mixed solution to the active intermediate suspension, maintain the temperature at 60℃, and continue stirring to mix thoroughly to obtain a modified precursor suspension;

[0022] S4. Adjust the pH of the ammonia-ethanol mixture to 8.0-8.5. Transfer the ammonia-ethanol mixture to a constant pressure dropping funnel and add it dropwise to the modified precursor suspension at room temperature. After the addition is complete, continue stirring to ensure complete hydrolysis and obtain the coated precursor suspension.

[0023] S5. Centrifuge the coated precursor suspension, discard the supernatant, and obtain a wet filter cake; wash the wet filter cake with anhydrous ethanol, and then dry it in a vacuum drying oven to obtain precursor powder.

[0024] S6. The precursor powder is placed into an alumina crucible, placed in a tube furnace, argon gas is introduced, and heated to 900°C to ensure that the organic components are completely decomposed and converted into the target oxide; the temperature is maintained, the furnace is cooled, and the mixture is ground to obtain modified zirconia.

[0025] Furthermore, the monoclinic zirconium oxide powder has a purity of ≥99%, a particle size D50 of 1.0-2.0 μm, and a specific surface area of ​​≥10 m². 2 / g.

[0026] Furthermore, the amount of modified tetrabutyl titanate added is 5% of the mass of zirconium oxide powder; the amount of modified boric acid added is 2% of the mass of zirconium oxide powder.

[0027] On the other hand, based on the same inventive concept, the present invention also provides a preparation process for an anti-erosion breathable brick, applicable to the aforementioned anti-erosion breathable brick, comprising the following steps:

[0028] M1. Mixing: Add fused magnesia particles to a roller mill and dry mix; add flake graphite, modified zirconium oxide, fine aluminum powder, and fine boron carbide powder in sequence and continue dry mixing; finally add phenolic resin and wet mix until the mud is uniformly black and can be formed into a ball by hand without crumbling, thus obtaining the mixed mud.

[0029] M2. Curing: The mixed mud is placed in a double-layered plastic bag and sealed. The mud is then cured at 20-30℃ to obtain the cured mud.

[0030] M3. Molding: The trapped mud is added into the permeable brick mold and molded by graded pressure using a hydraulic press to obtain the brick blank;

[0031] M4. Drying: Place the brick blanks in a drying kiln and dry them at 80-120℃ until the moisture content is <0.5%, thus obtaining dried brick blanks;

[0032] M5. Firing: The dried brick blanks are covered with coke particles and fired using a carbon-burying process to create a localized reducing atmosphere, preventing carbon and aluminum from oxidizing at high temperatures, ensuring the structural integrity of the material, and obtaining erosion-resistant and breathable bricks.

[0033] (3) Beneficial effects:

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. By chelating titanate with acetylacetone, its hydrolysis rate was effectively controlled, avoiding local agglomeration of titanium dioxide and forming a uniform nanoscale titanium source coating layer on the zirconium oxide surface. The esterification protection of boric acid with N-methyliminodiacetic acid solved the problems of boric acid's hygroscopicity and poor dispersion, achieving controlled release and uniform distribution of the boron component.

[0036] 2. When the working face is eroded by high-alkalinity slag (rich in calcium oxide), the titanium component in the modified layer preferentially reacts with the penetrating calcium oxide, forming a high-melting-point, chemically stable perovskite dense reaction layer in situ at the zirconium oxide particle interface, consuming and fixing Ca. 2+ This process blocks the chemical dissolution of the zirconium oxide core. Simultaneously, the boron component in the modified layer decomposes to generate boron trioxide, which spreads along the grain boundaries to form a high-viscosity borate-bound phase. This phase fills the grain boundary pores, blocking the physical channels for slag penetration; it also increases the viscosity of the interfacial slag, kinetically reducing Zr content. 4+ Ca 2+ The diffusion rate of plasma inhibits the precipitation of zirconium silicate dendrites.

[0037] 3. Two modified materials are generated in situ on the zirconium oxide surface via the sol-gel method, forming Zr-O-Ti chemical bonds with the matrix. These bonds exhibit high strength, good thermodynamic stability, and are not easily sloughed off by molten steel. Through a progressive blocking process of "titanium component for calcium fixation, boron component for pore plugging, and inhibition of dendrite precipitation," the "slag penetration—zirconia dissolution—Zr" process is effectively interrupted. 4+ The negative feedback loop of "migration-dendritic reprecipitation" extends the service life of permeable bricks under harsh smelting conditions. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating the process of preparing the erosion-resistant permeable brick according to Embodiment 1 of the present invention.

[0039] Figure 2 These are comparison images of the breathable bricks from Embodiment 1 and Comparative Example 2 of the present invention. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1: This example discloses an anti-erosion breathable brick, comprising the following components in parts by weight: 82.5 parts of fused magnesia particles, 11 parts of flake graphite, 4 parts of modified zirconium oxide fine powder, 2.5 parts of metallic aluminum fine powder, 1.5 parts of boron carbide fine powder, and 3.5 parts of phenolic resin.

[0042] The particle size of the fused magnesia particles includes 3-5mm, 1-3mm and 0-1mm sizes; the mass ratio of the 3-5mm fused magnesia particles, the 1-3mm fused magnesia particles and the 0-1mm fused magnesia particles is 3:3:4.

[0043] The modified zirconium oxide is a composite obtained by coating zirconium oxide with modified tetrabutyl titanate and modified boric acid and then heat-treating it; the modified tetrabutyl titanate is tetrabutyl titanate organically chelated with acetylacetone; the modified boric acid is boric acid organically esterified with N-methyliminodiacetic acid.

[0044] It should be noted that, as Figure 1 The diagram shown is a flowchart of the erosion-resistant permeable brick preparation process according to Embodiment 1 of the present invention. Figure 2 The image shown is a comparison of the breathable bricks in Embodiment 1 and Comparative Example 2 of the present invention.

[0045] The preparation method of the modified tetrabutyl titanate includes the following steps:

[0046] S11. Under nitrogen protection, 34.0 g of tetrabutyl titanate was dissolved in 100 mL of anhydrous ethanol to obtain an ethanol solution of tetrabutyl titanate; 12.0 g of acetylacetone was mixed with 30 mL of anhydrous ethanol to obtain an ethanol solution of acetylacetone.

[0047] S12. Under stirring, the ethanol solution of acetylacetone is added dropwise to the ethanol solution of tetrabutyl titanate; after the addition is complete, the temperature is raised to 60℃ and reacted for 3 hours to obtain mixed solution A; the solvent of mixed solution A is removed by rotary evaporation at 50℃ to obtain modified tetrabutyl titanate, which is then sealed and stored.

[0048] The molar ratio of tetrabutyl titanate to acetylacetone is 1:1.2.

[0049] The preparation method of the modified boric acid includes the following steps:

[0050] S21. Add 6.2g of boric acid, 14.7g of N-methyliminodiacetic acid, 100mL of dimethyl sulfoxide, 30mL of toluene and 0.5g of p-toluenesulfonic acid to the reaction flask in sequence, heat to 110-120℃ and reflux to remove water for 6-8 hours until no water is generated, to obtain mixed solution B;

[0051] S22. After cooling the mixed solution B, slowly pour it into 500 mL of diethyl ether at a rate of 5-10 mL / min under ice bath cooling at 0-5℃ to precipitate the precipitate; let it stand for 10 minutes to allow the precipitation to be complete, filter, and wash the filter cake A three times with diethyl ether at 0-5℃, each time using 50 mL, to obtain the crude product.

[0052] S23. Transfer the crude product to a 250 mL round-bottom flask, add 80 mL of acetone at 50-60 °C, and stir at 50-60 °C. If the solid is not completely dissolved after stirring for 10 minutes, add 5-10 mL of acetone at 50-60 °C each time until the solid is completely dissolved. Filter while hot (the funnel needs to be preheated). After the filtrate cools naturally to room temperature, place it in 0-5 °C to cool and crystallize for 2 hours. Filter by suction, and wash filter cake B once with 20 mL of acetone at 0-5 °C. Place filter cake B in a vacuum drying oven and dry at 40 °C (vacuum degree ≤ -0.08 MPa) for 12 hours to obtain modified boric acid.

[0053] The preparation method of the modified zirconia fine powder includes the following steps:

[0054] S1. Weigh 100g of monoclinic zirconium oxide powder, place it in a 500mL three-necked flask, add 300mL of anhydrous ethanol, and ultrasonically disperse for 30 minutes (power 300W, frequency 40kHz) to fully disperse the powder and obtain a suspension.

[0055] S2. Weigh out the modified tetrabutyl titanate and dissolve it in 50 mL of anhydrous ethanol to obtain the first mixed solution; transfer the first mixed solution into a constant pressure dropping funnel and add it dropwise to the suspension at a rate of 1 mL / min while stirring at 500 rpm; after the addition is complete, heat to 60℃ and stir the reaction at a constant temperature for 2 hours to obtain the active intermediate suspension.

[0056] S3. Weigh the modified boric acid and dissolve it in 30 mL of anhydrous ethanol to obtain a second mixed solution; add the second mixed solution to the active intermediate suspension, maintain the temperature at 60℃, and continue stirring for 1 hour to mix thoroughly to obtain a modified precursor suspension;

[0057] S4. Mix 5 mL of ammonia water with 50 mL of anhydrous ethanol to obtain an ammonia-ethanol mixed solution, and adjust the pH to 8.0-8.5; transfer the ammonia-ethanol mixed solution into a constant pressure dropping funnel, and add it dropwise to the modified precursor suspension at a rate of 0.5 mL / min at room temperature; after the addition is complete, continue stirring for 3 hours to ensure complete hydrolysis and obtain the coated precursor suspension;

[0058] S5. Centrifuge the coated precursor suspension (4000 rpm, 10 min), discard the supernatant to obtain a wet filter cake; wash the wet filter cake three times with anhydrous ethanol (200 mL each time), and then place it in a vacuum drying oven and dry at 60 °C for 12 hours to obtain precursor powder.

[0059] S6. The precursor powder is placed in an alumina crucible and then placed in a tube furnace. Argon gas (flow rate 0.5 L / min) is introduced and heated to 900°C at a heating rate of 5°C / min to ensure that the organic components are completely decomposed and converted into the target oxide. The mixture is held at this temperature for 2 hours, cooled with the furnace, and then gently ground and passed through a 200-mesh sieve to obtain modified zirconia.

[0060] The monoclinic zirconium oxide powder has a purity of ≥99%, a particle size D50 of 1.0-2.0 μm, and a specific surface area of ​​≥10 m². 2 / g.

[0061] The amount of modified tetrabutyl titanate added is 5% of the mass of zirconium oxide powder; the amount of modified boric acid added is 2% of the mass of zirconium oxide powder.

[0062] It should be noted that after heat treatment in an argon atmosphere at 900℃, the modified tetrabutyl titanate coated on the zirconium oxide surface decomposes into nano-sized anatase titanium dioxide; the modified boric acid decomposes to generate boron trioxide. The titanium dioxide forms a dense barrier layer on the zirconium oxide grain surface, preventing direct contact between the high-calcium oxide slag and the zirconium oxide core, thus inhibiting Zr... 4+ The slag dissolves. At the same time, boron trioxide spreads along the grain boundaries and preferentially reacts with the penetrating calcium oxide to form a high-melting-point boron-containing phase in situ, blocking the grain boundary channels through which the slag penetrates.

[0063] The preparation process of the erosion-resistant permeable brick includes the following steps:

[0064] M1. Mixing: Add fused magnesia particles to a roller mill and dry mix for 2 minutes; add flake graphite, modified zirconium oxide, fine aluminum powder, and fine boron carbide powder in sequence, and continue to dry mix for 3 minutes; finally add phenolic resin and wet mix for 15-20 minutes until the mud is uniformly black and can be formed into a ball by hand without crumbling, thus obtaining the mixed mud.

[0065] M2. Curing material: The mixed mud material is placed in a double-layered plastic bag and sealed. It is then cured at 20-30℃ for 12-24 hours to obtain the cured mud material.

[0066] M3. Molding: The trapped mud is added into the permeable brick mold and formed using a hydraulic press. The pressing process adopts a staged pressurization system: Pre-pressurization stage: First, pressurize at a low pressure of 30-50MPa and hold for 5-10 seconds to allow the particles to rearrange and expel gas; De-gassing stage: Depressurize to normal pressure and hold for 2-3 seconds to allow the gas to escape fully (can be repeated 1-2 times); Medium pressure stage: Pressurize to 80-120MPa and hold for 5-10 seconds to initially densify the green body; High pressure holding: Finally, pressurize to the target pressure of 150-200MPa and hold for 10-20 seconds to ensure that the green body reaches the designed density and obtain the brick blank;

[0067] M4. Drying: Place the brick blanks in a drying kiln and dry them at 80-120℃ for 24-48 hours until the moisture content is <0.5%, thus obtaining dried brick blanks;

[0068] M5. Firing: The dried brick blanks are covered with coke particles and fired using a carbon-buried process to create a localized reducing atmosphere, preventing carbon and aluminum from oxidizing at high temperatures and ensuring the structural integrity of the material. The firing regime is as follows: room temperature to 300℃ (heating rate 2℃ / min), 300-600℃ (heating rate 1℃ / min), 600-1000℃ (heating rate 2℃ / min), 1000-1500℃ (heating rate 3℃ / min), and held at 1500℃ for 3-5 hours. After holding, the cooling rate is controlled to ≤5℃ / min until below 800℃, and then the bricks are allowed to cool naturally to room temperature to obtain erosion-resistant and breathable bricks.

[0069] Example 2: This example is based on Example 1, but differs from Example 1 in that it includes the following components in parts by weight: 80 parts of fused magnesia particles, 10 parts of flake graphite, 3 parts of modified zirconium oxide fine powder, 2 parts of metallic aluminum fine powder, 1 part of boron carbide fine powder, and 3 parts of phenolic resin.

[0070] The other components and preparation process are the same as in Example 1.

[0071] Example 3: This example is based on Example 1, but differs from Example 1 in that it includes the following components in parts by weight: 85 parts of fused magnesia particles, 12 parts of flake graphite, 5 parts of modified zirconium oxide fine powder, 3 parts of metallic aluminum fine powder, 2 parts of boron carbide fine powder, and 4 parts of phenolic resin.

[0072] The other components and preparation process are the same as in Example 1.

[0073] Comparative Example 1: This comparative example is based on Example 1, except that unmodified tetrabutyl titanate is used instead of modified tetrabutyl titanate in this comparative example. Other components and preparation processes are the same as in Example 1.

[0074] Comparative Example 2: This comparative example is based on Example 1, except that unmodified boric acid is used instead of modified boric acid in this comparative example. Other components and preparation processes are the same as in Example 1.

[0075] Comparative Example 3: This comparative example is based on Example 1, but differs from Example 1 in that it uses unmodified tetrabutyl titanate and unmodified boric acid-coated and heat-treated zirconium oxide. Other components and preparation processes are the same as in Example 1.

[0076] Comparative Example 4: This comparative example is based on Example 1, but differs from Example 1 in that the modified zirconium oxide in this comparative example does not contain modified tetrabutyl titanate, while the other components and preparation process are the same as in Example 1.

[0077] The preparation method of the modified zirconia material includes the following steps:

[0078] S1. Weigh 100g of monoclinic zirconium oxide powder, place it in a 500mL three-necked flask, add 300mL of anhydrous ethanol, and ultrasonically disperse for 30 minutes (power 300W, frequency 40kHz) to fully disperse the powder and obtain a suspension.

[0079] S2. Weigh out modified boric acid (2% of the mass of zirconium oxide powder) and dissolve it in 30 mL of anhydrous ethanol to obtain a second mixed solution; add the second mixed solution to the suspension, maintain the temperature at 60℃, and stir for 1 hour to mix thoroughly to obtain a boron-containing precursor suspension;

[0080] S3. Mix 5 mL of ammonia water with 50 mL of anhydrous ethanol to obtain an ammonia-ethanol mixed solution, and adjust its pH to 8.0-8.5; transfer the ammonia-ethanol mixed solution into a constant pressure dropping funnel, and add it dropwise to the boron-containing precursor suspension at a rate of 0.5 mL / min at room temperature; after the addition is complete, continue stirring for 3 hours to ensure complete hydrolysis, and obtain a boron-coated precursor suspension;

[0081] S4. Centrifuge the boron-coated precursor suspension (4000 rpm, 10 min), discard the supernatant, and obtain solid product A; wash solid product A three times with anhydrous ethanol (200 mL each time), and place it in a vacuum drying oven and dry at 60 °C for 12 hours to obtain boron-coated precursor powder.

[0082] S5. The boron-containing precursor powder is placed into an alumina crucible and then into a tube furnace. Argon gas (flow rate 0.5 L / min) is introduced and heated to 900°C at a heating rate of 5°C / min. The temperature is held for 2 hours, cooled with the furnace, and then gently ground and passed through a 200-mesh sieve to obtain modified zirconia.

[0083] Comparative Example 5: This comparative example is based on Example 1, but differs from Example 1 in that the modified zirconium oxide in this comparative example does not contain modified boric acid, while the other components and preparation process are the same as in Example 1.

[0084] The method for preparing the modified zirconium oxide includes the following steps:

[0085] S1. Weigh 100g of monoclinic zirconium oxide powder, place it in a 500mL three-necked flask, add 300mL of anhydrous ethanol, and ultrasonically disperse for 30 minutes (power 300W, frequency 40kHz) to fully disperse the powder and obtain a suspension.

[0086] S2. Weigh out 5% of the modified tetrabutyl titanate (by mass of zirconium oxide powder) and dissolve it in 50 mL of anhydrous ethanol to obtain a first mixed solution; transfer the first mixed solution into a constant pressure dropping funnel and add it dropwise to the suspension at a rate of 1 mL / min while stirring at 500 rpm; after the addition is complete, raise the temperature to 60 °C and stir the reaction at a constant temperature for 2 hours to obtain an active intermediate suspension; maintain the temperature at 60 °C and continue stirring for 1 hour to obtain a titanium-modified precursor suspension;

[0087] S3. Mix 5 mL of ammonia water with 50 mL of anhydrous ethanol to obtain an ammonia-ethanol mixed solution, and adjust its pH to 8.0-8.5; transfer the ammonia-ethanol mixed solution into a constant pressure dropping funnel, and add it dropwise to the titanium modified precursor suspension at a rate of 0.5 mL / min at room temperature; after the addition is complete, continue stirring for 3 hours to ensure complete hydrolysis and obtain a titanium sol-coated suspension;

[0088] S4. Centrifuge the titanium sol-coated suspension (4000 rpm, 10 minutes), discard the supernatant, and obtain solid product B; wash solid product B three times with anhydrous ethanol (200 mL each time), and place it in a vacuum drying oven and dry at 60°C for 12 hours to obtain titanium-coated precursor powder.

[0089] S5. The titanium-coated precursor powder is placed into an alumina crucible and then into a tube furnace. Argon gas (flow rate 0.5 L / min) is introduced and heated to 900°C at a heating rate of 5°C / min. The temperature is held for 2 hours, cooled with the furnace, and then gently ground and passed through a 200-mesh sieve to obtain modified zirconia.

[0090] Comparative Example 6: This comparative example is based on Example 1, but differs from Example 1 in that monoclinic zirconium oxide powder is used instead of modified zirconium oxide. Other components and preparation processes are the same as in Example 1.

[0091] Comparative Example 7: This comparative example is based on Example 1, but differs from Example 1 in that the permeable brick in this comparative example does not contain modified zirconium oxide. The other components and preparation process are the same as in Example 1.

[0092] Comparative Example 8: This comparative example is based on Example 1, but differs from Example 1 in that the fused magnesia particles in this comparative example do not use particle sizes of 3-5mm, 1-3mm, and 0-1mm, but only use fused magnesia particles of a single particle size of 1-3mm. Other components and preparation processes are the same as in Example 1.

[0093] Experimental verification:

[0094] 1. Slag Erosion Resistance Test: Refer to T / CSTM00436—2021. The permeable bricks prepared in each example and comparative example were processed into 70mm×70mm×70mm square-core crucible samples, with a central hole diameter of 20mm and a depth of 30mm. The samples were held at 1650℃ for 3 hours in a high-frequency induction furnace using high-alkalinity refining slag (calcium oxide content 55%, silica 15%, alumina 20%, magnesium oxide 10%). After the test, the samples were cut along the centerline, and the maximum slag erosion depth and maximum penetration depth were measured.

[0095] 2. Thermal shock stability test: Refer to GB / T30873. Heat each specimen to 1100℃ and hold for 30 minutes. Remove and quickly immerse in running water at 20±5℃ for 5 minutes. Repeat this cycle. After every 5 cycles, test the flexural strength at room temperature and calculate the strength retention rate (strength after thermal shock / strength before thermal shock × 100%). Continue until the strength retention rate is less than 60% or the specimen breaks, and record the number of cycles.

[0096] 3. Determination of apparent porosity: Refer to GB / T2997-2015. Apparent porosity is determined using the vacuum method.

[0097] 4. Microstructure observation: The microstructure of the working surface of the etched sample was observed using a scanning electron microscope, with a focus on the morphology of the reaction layer at the zirconium oxide particle interface, the grain boundary filling, and the presence of dendritic precipitates.

[0098] Table 1. Results of erosion resistance test, thermal shock stability test and apparent porosity test:

[0099]

[0100] Table 2. Observation results of microstructure:

[0101]

[0102] As shown in Tables 1 and 2, Examples 1-3, which simultaneously use modified tetrabutyl titanate and modified boric acid, exhibit better results in terms of slag erosion resistance depth, slag penetration resistance depth, post-thermal shock strength retention rate, and apparent porosity than the comparative examples using only one modified component or no modified component. The microstructure shows that the interfacial reaction layer is continuous or continuously dense, the grain boundaries are completely filled, and there is no dendrite precipitation, confirming that both modified components are necessary conditions for achieving the technical effects of this invention.

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An erosion-resistant and breathable brick, characterized in that, The composition includes the following components in parts by weight: 80-85 parts fused magnesia particles, 10-12 parts flake graphite, 3-5 parts modified zirconium oxide fine powder, 2-3 parts metallic aluminum fine powder, 1-2 parts boron carbide fine powder, and 3-4 parts phenolic resin. The particle size of the fused magnesia particles includes 3-5mm, 1-3mm and 0-1mm sizes; the mass ratio of the 3-5mm fused magnesia particles, the 1-3mm fused magnesia particles and the 0-1mm fused magnesia particles is 3:3:

4. The modified zirconium oxide is a composite obtained by coating zirconium oxide with modified tetrabutyl titanate and modified boric acid and then heat-treating it; the modified tetrabutyl titanate is tetrabutyl titanate organically chelated with acetylacetone; the modified boric acid is boric acid organically esterified with N-methyliminodiacetic acid; and the heat treatment temperature is 900℃.

2. The erosion-resistant and breathable brick according to claim 1, characterized in that, The preparation method of the modified tetrabutyl titanate includes the following steps: S11. Under nitrogen protection, tetrabutyl titanate is dissolved in anhydrous ethanol to obtain an ethanol solution of tetrabutyl titanate; acetylacetone is mixed with anhydrous ethanol to obtain an ethanol solution of acetylacetone. S12. Under stirring, an ethanol solution of acetylacetone is added dropwise to an ethanol solution of tetrabutyl titanate; after the addition is complete, the temperature is raised to 60°C to react and a mixed solution A is obtained; the mixed solution A is evaporated by rotary evaporation to obtain modified tetrabutyl titanate.

3. The erosion-resistant and breathable brick according to claim 2, characterized in that, The molar ratio of tetrabutyl titanate to acetylacetone is 1:1.

2.

4. The erosion-resistant and breathable brick according to claim 1, characterized in that, The preparation method of the modified boric acid includes the following steps: S21. Add boric acid, N-methyliminodiacetic acid, dimethyl sulfoxide, toluene and p-toluenesulfonic acid to the reaction flask in sequence, heat to 110-120℃ and reflux to separate water until no water is generated, to obtain mixed solution B; S22. After cooling the mixed solution B, slowly pour it into diethyl ether while cooling to precipitate the precipitate; let it stand, filter it, and wash the filter cake A with diethyl ether at 0-5℃ to obtain the crude product; S23. Transfer the crude product to a round-bottom flask, add acetone at 50-60℃ and stir. If the solid is not completely dissolved, add more acetone at 50-60℃ until the solid is completely dissolved. Filter while hot, and after the filtrate cools naturally to room temperature, place it in 0-5℃ to cool and crystallize. Filter by suction, and wash filter cake B with acetone at 0-5℃. Place filter cake B in a vacuum drying oven to dry and obtain modified boric acid.

5. The erosion-resistant and breathable brick according to claim 1, characterized in that, The preparation method of the modified zirconia fine powder includes the following steps: S1. Weigh monoclinic zirconium oxide powder, place it in a three-necked flask, add anhydrous ethanol, and disperse it by ultrasonication to obtain a suspension; S2. Weigh out the modified tetrabutyl titanate and dissolve it in anhydrous ethanol to obtain the first mixed solution; transfer the first mixed solution into a constant pressure dropping funnel and add it dropwise into the suspension while stirring; after the addition is complete, raise the temperature to 60°C and stir the reaction at a constant temperature to obtain the active intermediate suspension. S3. Weigh the modified boric acid and dissolve it in anhydrous ethanol to obtain a second mixed solution; add the second mixed solution to the active intermediate suspension, maintain the temperature at 60℃, and continue stirring to mix thoroughly to obtain a modified precursor suspension; S4. The pH of the ammonia-ethanol mixture obtained by mixing ammonia water and anhydrous ethanol is adjusted to 8.0-8.5; the ammonia-ethanol mixture is transferred into a constant pressure dropping funnel and added dropwise to the modified precursor suspension at room temperature; after the addition is complete, stirring is continued to obtain the coated precursor suspension. S5. Centrifuge the coated precursor suspension, discard the supernatant, and obtain a wet filter cake; wash the wet filter cake with anhydrous ethanol, and then dry it in a vacuum drying oven to obtain precursor powder. S6. The precursor powder is placed into an alumina crucible, placed in a tube furnace, argon gas is introduced, heated to 900°C, held at that temperature, cooled with the furnace, and ground to obtain modified zirconia.

6. The erosion-resistant and breathable brick according to claim 5, characterized in that, The monoclinic zirconia powder has a purity of ≥99%, a particle size D50 of 1.0-2.0μm, and a specific surface area of ​​≥10m² / g.

7. The erosion-resistant and breathable brick according to claim 5, characterized in that, The amount of modified tetrabutyl titanate added is 5% of the mass of zirconium oxide powder; the amount of modified boric acid added is 2% of the mass of zirconium oxide powder.

8. A process for preparing an erosion-resistant permeable brick, applied to the preparation of an erosion-resistant permeable brick as described in any one of claims 1 to 7, characterized in that, The process includes the following steps: M1. Mixing: Add fused magnesia particles to a roller mill and dry mix; add flake graphite, modified zirconium oxide, fine aluminum powder, and fine boron carbide powder in sequence and continue dry mixing; finally add phenolic resin and wet mix until the mud is uniformly black and can be formed into a ball by hand without crumbling, thus obtaining the mixed mud. M2. Curing: The mixed mud is placed in a double-layered plastic bag and sealed. The mud is then cured at 20-30℃ to obtain the cured mud. M3. Molding: The trapped mud is added into the permeable brick mold and molded by graded pressure using a hydraulic press to obtain the brick blank; M4. Drying: Place the brick blanks in a drying kiln and dry them at 80-120℃ until the moisture content is <0.5%, thus obtaining dried brick blanks; M5. Firing: The dried brick blanks are covered with coke particles and fired using a carbon-burying process to obtain erosion-resistant and breathable bricks.

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