A green refractory and thermal shock resistant slag-blocking sliding plate for converter and its preparation method

Abstract

This invention relates to the field of green special refractory ceramics technology, and particularly to a green refractory thermal shock resistant converter slag-blocking sliding plate and its preparation method. The raw materials for the aforementioned green refractory thermal shock resistant converter slag-blocking sliding plate, by weight, include: 50-80 parts of tabular corundum particles, 10-20 parts of fine tabular corundum powder, 1-3 parts of α-alumina micro powder, 5-10 parts of zirconium mullite, 5-10 parts of dispersed graphite, 1-2 parts of carbon fiber, 1-2 parts of silica micro powder, 1-2 parts of titanium powder, 1-5 parts of boron nitride, 1-5 parts of boron carbide, and 1-3 parts of phenolic resin; the raw materials for the dispersed graphite include: flake graphite powder, ferric nitrate, urea, potassium nitrate, and surfactant; the mass ratio of flake graphite powder, ferric nitrate, urea, potassium nitrate, and surfactant is 5-10:1-3:1-3:1-2:1-2. The thermal shock resistance, compressive strength, and high-temperature flexural strength of the converter slag-blocking sliding plate obtained by this invention are simultaneously improved.

Description

Technical Field

[0001] This invention relates to the field of green special refractory ceramics technology, and in particular to a green refractory thermal shock resistant converter slag-blocking sliding plate and its preparation method. Background Technology

[0002] Iron and steel smelting, a pillar of modern industry, involves key processes such as charging, slag formation, and tapping. During converter steelmaking, slag entering subsequent processes can lead to problems such as refractory material loss, decreased steel quality, and increased alloy consumption. Traditional slag-blocking methods, such as slag caps and slag balls, cannot control slag flow throughout the entire process. While sliding plate slag-blocking technology effectively solves this problem by adjusting the molten steel flow rate, the sliding plate must withstand high-temperature molten steel erosion, thermal shock, and oxidative wear, placing extremely high demands on its material properties.

[0003] Existing converter slag baffle plates mostly use re-fired aluminum zirconium carbon or composite zirconium structures. Although they have a certain degree of corrosion resistance, they have significant drawbacks: poor thermal shock resistance, with frequent high and low temperature transitions easily leading to crack propagation; insufficient compressive strength, making it difficult to withstand the erosion of steel slag; and limited high-temperature flexural strength, affecting long-term stability. In addition, traditional processes require high-temperature firing, resulting in high costs and short service life. While zirconium-embedded structures extend the service life, they are more complex to produce and increase safety hazards.

[0004] How to provide a green special refractory ceramic that optimizes the environmentally friendly formula while simultaneously improving thermal shock resistance, compressive strength, and high-temperature flexural strength to meet the requirements of extreme working conditions in converters not only conforms to the trend of green manufacturing, but also significantly improves the life of the slide plate and reduces the overall cost, thus playing an important role in promoting clean steel smelting. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and to propose a green refractory and thermal shock resistant converter slag-blocking sliding plate and its preparation method.

[0006] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include, by weight: 50-80 parts of tabular corundum particles, 10-20 parts of tabular corundum fine powder, 1-3 parts of α-alumina micro powder, 5-10 parts of zircon mullite, 5-10 parts of dispersed graphite, 1-2 parts of carbon fiber, 1-2 parts of silica micro powder, 1-2 parts of titanium powder, 1-5 parts of boron nitride, 1-5 parts of boron carbide, and 1-3 parts of phenolic resin.

[0007] The raw materials for dispersed graphite include: flake graphite powder, ferric nitrate, urea, potassium nitrate, and surfactant; the mass ratio of flake graphite powder, ferric nitrate, urea, potassium nitrate, and surfactant is 5-10:1-3:1-3:1-2:1-2.

[0008] Preferably, the tabular corundum particles comprise, by mass percentage: 20-30% tabular corundum particles with a particle size of 0.1-0.5 mm, 20-30% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder being tabular corundum particles with a particle size of 1-3 mm.

[0009] Preferably, the particle size of the tabular corundum powder is 0.01-0.1 mm.

[0010] Preferably, the zircon mullite has a grain size of 0.5-1 mm.

[0011] Preferably, the dispersed graphite is prepared by the following steps: flake graphite powder is soaked in hydrofluoric acid solution, stirred at 50-60℃ for 2-4 hours, filtered, washed, and vacuum dried to obtain pretreated graphite; ferric nitrate, urea, potassium nitrate, and surfactant are added to water, stirred at 50-60℃ for 1-2 hours, the pretreated graphite is added and ultrasonically treated for 1-2 hours, filtered, washed, and vacuum dried.

[0012] Preferably, the hydrofluoric acid solution has a mass fraction of 5-10%, and the surfactant is sodium hexadecyl sulfate.

[0013] Preferably, the ultrasonic frequency is 50-60kHz.

[0014] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0015] S1. Stir the plate-shaped corundum particles, α-alumina micro powder, and dispersed graphite for 10-20 minutes to obtain a premix;

[0016] S2. Dry mix the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide for 5-10 minutes, then add phenolic resin and mix for 5-15 minutes to obtain the compound.

[0017] S3. Add premixed material to the mixture and mix for 30-60 minutes. Pour into a mold and press into shape. Let it air dry naturally for 5-10 hours. Under an inert atmosphere, heat to 190-250℃ and hold for 1-2 minutes. Then heat to 600-700℃ and hold for 10-13 hours. Finally, cool to 200-250℃ to obtain a brick blank.

[0018] S4. Soak the brick blanks in oil for 2-5 hours, then remove them and put them back into the kiln. Under an inert atmosphere, heat the kiln to 400-500℃, hold for 5-10 hours, and let them cool naturally to room temperature.

[0019] Preferably, in S3, during the process of heating to 190-250℃, the heating rate is 1-2℃ / min.

[0020] Preferably, in S3, during the process of heating to 600-700℃, the heating rate is 2-4℃ / min.

[0021] Preferably, in S3, during the process of cooling down to 200-250℃, the cooling rate is 1-3℃ / min.

[0022] Preferably, in S4, during the process of heating to 400-500℃, the heating rate is 1-3℃ / min.

[0023] Beneficial effects:

[0024] This invention uses a compound of plate-shaped corundum particles, α-alumina micro powder, and dispersed graphite, which have high dispersion uniformity. During the high-temperature treatment in the kiln, the urea, potassium nitrate, and ferric nitrate intercalated in the dispersed graphite decompose to form gas, which promotes high pressure between the graphite layers and causes the graphite flakes to open along the base surface. In the thermal shock environment, it can effectively absorb and disperse stress, significantly alleviate the hot damage of the slide plate. The iron element can also form nanocrystals with carbon as structural support, which significantly enhances the compressive strength.

[0025] This invention employs a composite of dispersed graphite with high specific surface area, silicon micropowder, and titanium powder. Silicon micropowder reacts with carbon to form a silicon carbide ceramic phase, while titanium powder reacts with carbon and nitrogen to form a titanium carbonitride ceramic phase. Boron nitride acts as a seed crystal to promote the formation of a non-oxide ceramic phase, resulting in a dense ceramic network. Under high pressure, the composite of the silicon carbide and titanium carbonitride ceramic phases provides rigid support, while the layered structure of graphite dissipates energy through plastic deformation. Together, they resist the erosion of steel slag. Simultaneously, the high dispersibility of the dispersed graphite optimizes the particle interface bonding, reduces stress concentration points, and significantly improves the overall high-temperature flexural strength.

[0026] The thermal shock resistance, compressive strength and high-temperature flexural strength of the slide plate for converter slag blocking obtained by this invention are improved simultaneously, while energy consumption is reduced, service life is extended, and overall performance is excellent, making it suitable for large-scale promotion and application. Attached Figure Description

[0027] Figure 1 The diagram shows a comparison of the room temperature compressive strength and high temperature compressive strength of the converter slag-blocking sliding plate obtained in Example 5 and Comparative Examples 1-2.

[0028] Figure 2 The high-temperature flexural strength and thermal shock stability of the slide plates for converter slag blocking obtained in Example 5 and Comparative Examples 1-2 are compared.

[0029] Figure 3 The diagram shows a comparison of the apparent porosity and oxidation resistance of the slide plates used for slag blocking in converters obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments.

[0031] The following materials were purchased: Tabular corundum particles from Zibo Mouze New Material Technology Co., Ltd.; Tabular corundum fine powder from Qinghe County Moujiang Metal Materials Co., Ltd. (particle size 0.01-0.1 mm); α-alumina micro powder from Zibo Moujia Wear-Resistant Ceramics Co., Ltd. (500 mesh); Zircon mullite from Shijiazhuang Moujin Mineral Products Co., Ltd. (particle size 0.5-1 mm); Flake graphite powder from Qingdao Mourun Chenyue Graphite Co., Ltd. (1000 mesh); Carbon fiber from Toray New Materials Co., Ltd. (7 μm diameter, 2 ± 0.2 mm length); Silica microparticles from Lingshou County Mouqi Mineral Products Co., Ltd. (1250 mesh); Titanium powder from Qinghe County Moudong Metal Materials Co., Ltd. (15-50 μm particle size); and Boron nitride from Hebei Moubi Metal Materials Co., Ltd. (2000 mesh). The boron carbide used below was purchased from Nangong City Moubang New Material Technology Co., Ltd., 2000 mesh. The phenolic resin used below was purchased from Jinan Mouhui Chemical Technology Co., Ltd., 500 mesh.

[0032] Example 1

[0033] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include: 500g of tabular corundum particles, 100g of tabular corundum fine powder, 10g of α-alumina micro powder, 50g of zircon mullite, 50g of dispersed graphite, 10g of carbon fiber, 10g of silica micro powder, 10g of titanium powder, 10g of boron nitride, 10g of boron carbide, and 10g of phenolic resin.

[0034] The tabular corundum particles comprise, by mass percentage: 20% tabular corundum particles with a particle size of 0.1-0.5 mm, 20% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder tabular corundum particles with a particle size of 1-3 mm.

[0035] Dispersed graphite was prepared using the following steps: 50g of flake graphite powder was soaked in a 5% hydrofluoric acid solution and stirred at 50℃ for 2 hours. The solution was then filtered, washed, and vacuum dried to obtain pretreated graphite. 10g of ferric nitrate, 10g of urea, 1g of potassium nitrate, and 10g of sodium hexadecyl sulfate were added to 400g of deionized water and stirred at 50℃ for 1 hour. The pretreated graphite was then added and ultrasonically treated for 1 hour at a frequency of 50-60kHz. The solution was then filtered, washed, and vacuum dried.

[0036] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0037] S1. Add the plate-shaped corundum particles, α-alumina micro powder, and dispersed graphite into a mixer and stir for 10 minutes to obtain a premix.

[0038] S2. Add the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide to the mixer and dry mix for 5 minutes. Then add phenolic resin and mix for 5 minutes to obtain the mixture.

[0039] S3. Add premixed material to the mixture and mix for 30 minutes. Add the mixture to the mold and press it into shape. Let it air dry naturally for 5 hours. Under the protection of an inert atmosphere, put it into a kiln and heat it to 190°C at a rate of 1°C / min. Hold it for 1 minute. Then heat it to 600°C at a rate of 2°C / min. Hold it for 10 hours. Then cool it down to 200°C at a rate of 1°C / min to obtain the brick blank.

[0040] S4. Soak the brick blanks in oil for 2 hours, set the pressure to 1MPa, take them out and put them back into the kiln. Under the protection of an inert atmosphere, heat them to 400℃ at a rate of 1℃ / min, keep them at that temperature for 5 hours, and let them cool naturally to room temperature.

[0041] Example 2

[0042] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include: 800g of tabular corundum particles, 200g of tabular corundum fine powder, 30g of α-alumina micro powder, 100g of zircon mullite, 100g of dispersed graphite, 20g of carbon fiber, 20g of silica micro powder, 20g of titanium powder, 50g of boron nitride, 50g of boron carbide, and 30g of phenolic resin.

[0043] The tabular corundum particles comprise, by mass percentage: 30% tabular corundum particles with a particle size of 0.1-0.5 mm, 30% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder tabular corundum particles with a particle size of 1-3 mm.

[0044] Dispersed graphite was prepared using the following steps: 100g of flake graphite powder was soaked in a 10% hydrofluoric acid solution and stirred at 60℃ for 4 hours. The solution was then filtered, washed, and vacuum dried to obtain pretreated graphite. 30g of ferric nitrate, 30g of urea, 20g of potassium nitrate, and 20g of sodium hexadecyl sulfate were added to 800g of deionized water and stirred at 60℃ for 2 hours. The pretreated graphite was then added and ultrasonically treated for 2 hours at a frequency of 60kHz. The solution was then filtered, washed, and vacuum dried.

[0045] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0046] S1. Add the tabular corundum particles, α-alumina micro powder, and dispersed graphite into a mixer and stir for 20 minutes to obtain a premix.

[0047] S2. Add the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide to the mixer and dry mix for 10 minutes. Then add phenolic resin and mix for 15 minutes to obtain the mixture.

[0048] S3. Add premixed material to the mixture and mix for 60 minutes. Add the mixture to the mold and press it into shape. Let it air dry naturally for 10 hours. Under inert atmosphere protection, put it into the kiln and heat it to 250°C at a rate of 2°C / min. Hold it for 2 minutes. Then heat it to 700°C at a rate of 4°C / min. Hold it for 13 hours. Then cool it down to 250°C at a rate of 3°C / min to obtain the brick blank.

[0049] S4. Soak the brick blanks in oil for 5 hours, set the pressure to 1.5 MPa, take them out and put them back into the kiln. Under the protection of an inert atmosphere, heat them to 500℃ at a rate of 3℃ / min, keep them at that temperature for 10 hours, and let them cool naturally to room temperature.

[0050] Example 3

[0051] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include: 600g of tabular corundum particles, 180g of tabular corundum fine powder, 15g of α-alumina micro powder, 90g of zircon mullite, 70g of dispersed graphite, 18g of carbon fiber, 13g of silica micro powder, 18g of titanium powder, 20g of boron nitride, 40g of boron carbide, and 15g of phenolic resin.

[0052] The tabular corundum particles comprise, by mass percentage: 25% tabular corundum particles with a particle size of 0.1-0.5 mm, 25% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder tabular corundum particles with a particle size of 1-3 mm.

[0053] Dispersed graphite was prepared using the following steps: 90g of flake graphite powder was soaked in a 7% hydrofluoric acid solution and stirred at 58℃ for 2.5h. After filtration, washing, and vacuum drying, pretreated graphite was obtained. 25g of ferric nitrate, 15g of urea, 18g of potassium nitrate, and 13g of sodium hexadecyl sulfate were added to 700g of deionized water and stirred at 53℃ for 100min. The pretreated graphite was then added and ultrasonically treated for 80min at a frequency of 58kHz. After filtration, washing, and vacuum drying, the graphite was obtained.

[0054] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0055] S1. Add the tabular corundum particles, α-alumina micro powder, and dispersed graphite into a mixer and stir for 12 minutes to obtain a premix.

[0056] S2. Add the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide to the mixer and dry mix for 9 minutes. Then add phenolic resin and mix for 8 minutes to obtain the mixture.

[0057] S3. Add premixed material to the mixture and mix for 50 minutes. Pour into a mold and press into shape. Let it air dry naturally for 7 hours. Under inert atmosphere protection, put it into a kiln and heat it to 200℃ at a rate of 1.7℃ / min. Hold for 1.5 minutes. Heat it to 620℃ at a rate of 3.5℃ / min. Hold for 12 hours. Cool it down to 230℃ at a rate of 1.5℃ / min to obtain brick blanks.

[0058] S4. Soak the brick blanks in oil for 3 hours, set the pressure to 1.3 MPa, take them out and put them back into the kiln. Under the protection of an inert atmosphere, heat them to 480℃ at a rate of 1.5℃ / min, hold them at that temperature for 7 hours, and let them cool naturally to room temperature.

[0059] Example 4

[0060] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include: 700g of tabular corundum particles, 120g of tabular corundum fine powder, 25g of α-alumina micro powder, 70g of zircon mullite, 90g of dispersed graphite, 12g of carbon fiber, 17g of silica micro powder, 12g of titanium powder, 40g of boron nitride, 20g of boron carbide, and 25g of phenolic resin.

[0061] The tabular corundum particles comprise, by mass percentage: 25% tabular corundum particles with a particle size of 0.1-0.5 mm, 25% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder tabular corundum particles with a particle size of 1-3 mm.

[0062] Dispersed graphite was prepared using the following steps: 70g of flake graphite powder was soaked in a 9% hydrofluoric acid solution and stirred at 52℃ for 3.5h. After filtration, washing, and vacuum drying, pretreated graphite was obtained. 15g of ferric nitrate, 25g of urea, 12g of potassium nitrate, and 17g of sodium hexadecyl sulfate were added to 500g of deionized water and stirred at 57℃ for 80min. The pretreated graphite was then added and ultrasonically treated for 100min at a frequency of 52kHz. After filtration, washing, and vacuum drying, the graphite was obtained.

[0063] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0064] S1. Add the plate-shaped corundum particles, α-alumina micro powder, and dispersed graphite into a mixer and stir for 18 minutes to obtain a premix.

[0065] S2. Add the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide to the mixer and dry mix for 7 minutes. Add phenolic resin and mix for 12 minutes to obtain the mixture.

[0066] S3. Add premixed material to the mixture and mix for 40 minutes. Pour into a mold and press into shape. Let it air dry naturally for 9 hours. Under inert atmosphere protection, put it into a kiln and heat it to 240℃ at a rate of 1.3℃ / min. Hold for 1.5 minutes. Heat it to 680℃ at a rate of 2.5℃ / min. Hold for 11 hours. Cool it down to 210℃ at a rate of 2.5℃ / min to obtain brick blanks.

[0067] S4. Soak the brick blanks in oil for 4 hours, set the pressure to 1.1 MPa, take them out and put them back into the kiln. Under the protection of an inert atmosphere, heat them to 420℃ at a rate of 2.5℃ / min, hold them at that temperature for 9 hours, and let them cool naturally to room temperature.

[0068] Example 5

[0069] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include: 650g of tabular corundum particles, 150g of tabular corundum fine powder, 20g of α-alumina micro powder, 80g of zircon mullite, 80g of dispersed graphite, 15g of carbon fiber, 15g of silica micro powder, 15g of titanium powder, 30g of boron nitride, 30g of boron carbide, and 20g of phenolic resin.

[0070] The tabular corundum particles comprise, by mass percentage: 25% tabular corundum particles with a particle size of 0.1-0.5 mm, 25% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder tabular corundum particles with a particle size of 1-3 mm.

[0071] Dispersed graphite was prepared using the following steps: 80g of flake graphite powder was soaked in an 8% hydrofluoric acid solution and stirred at 55℃ for 3 hours. The solution was then filtered, washed, and vacuum dried to obtain pretreated graphite. 20g of ferric nitrate, 20g of urea, 15g of potassium nitrate, and 15g of sodium hexadecyl sulfate were added to 600g of deionized water and stirred at 55℃ for 90 minutes. The pretreated graphite was then added and ultrasonically treated for 90 minutes at a frequency of 55kHz. The solution was then filtered, washed, and vacuum dried.

[0072] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0073] S1. Add the plate-shaped corundum particles, α-alumina micro powder, and dispersed graphite to a mixer and stir for 15 minutes to obtain a premix.

[0074] S2. Add the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide to the mixer and dry mix for 8 minutes. Add phenolic resin and mix for 10 minutes to obtain the mixture.

[0075] S3. Add premixed material to the mixture and mix for 45 minutes. Pour into a mold and press into shape. Let it air dry naturally for 8 hours. Under inert atmosphere protection, put it into a kiln and heat it to 220°C at a rate of 1.5°C / min. Hold for 1.5 minutes. Then heat it to 650°C at a rate of 3°C / min. Hold for 11.5 hours. Finally, cool it down to 220°C at a rate of 2°C / min to obtain the brick blank.

[0076] S4. Soak the brick blanks in asphalt oil for 3.5 hours at a pressure of 1.2 MPa and an oil soaking temperature of 200℃. After removing them, put them back into the kiln and heat them to 450℃ at a rate of 2℃ / min under an inert atmosphere. Hold them at that temperature for 8 hours and let them cool naturally to room temperature.

[0077] Comparative Example 1

[0078] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include: 650g of tabular corundum particles, 150g of tabular corundum fine powder, 20g of α-alumina micro powder, 80g of zircon mullite, 80g of flake graphite powder, 15g of carbon fiber, 15g of silicon micro powder, 15g of titanium powder, 30g of boron nitride, 30g of boron carbide, and 20g of phenolic resin.

[0079] The tabular corundum particles comprise, by mass percentage: 25% tabular corundum particles with a particle size of 0.1-0.5 mm, 25% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder tabular corundum particles with a particle size of 1-3 mm.

[0080] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0081] S1. Add the tabular corundum particles, α-alumina micro powder, and flake graphite powder to a mixer and stir for 15 minutes to obtain a premix.

[0082] S2. Add the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide to the mixer and dry mix for 8 minutes. Add phenolic resin and mix for 10 minutes to obtain the mixture.

[0083] S3. Add premixed material to the mixture and mix for 45 minutes. Pour into a mold and press into shape. Let it air dry naturally for 8 hours. Under inert atmosphere protection, put it into a kiln and heat it to 220°C at a rate of 1.5°C / min. Hold for 1.5 minutes. Then heat it to 650°C at a rate of 3°C / min. Hold for 11.5 hours. Finally, cool it down to 220°C at a rate of 2°C / min to obtain the brick blank.

[0084] S4. Soak the brick blanks in asphalt oil for 3.5 hours at a pressure of 1.2 MPa and an oil soaking temperature of 200℃. After removing them, put them back into the kiln and heat them to 450℃ at a rate of 2℃ / min under an inert atmosphere. Hold them at that temperature for 8 hours and let them cool naturally to room temperature.

[0085] Comparative Example 2

[0086] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include: 650g of tabular corundum particles, 150g of tabular corundum fine powder, 20g of α-alumina micro powder, 80g of zircon mullite, 80g of dispersed graphite, 15g of carbon fiber, 15g of silica micro powder, 15g of titanium powder, 30g of boron nitride, 30g of boron carbide, and 20g of phenolic resin.

[0087] The tabular corundum particles comprise, by mass percentage: 25% tabular corundum particles with a particle size of 0.1-0.5 mm, 25% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder tabular corundum particles with a particle size of 1-3 mm.

[0088] Dispersed graphite is prepared by the following steps: 20g ferric nitrate, 20g urea, 15g potassium nitrate, and 15g sodium hexadecyl sulfate are added to 600g deionized water and stirred at 55℃ for 90min. Then, 80g flake graphite powder is added and ultrasonically treated for 90min at a frequency of 55kHz. The mixture is then filtered, washed, and vacuum dried.

[0089] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0090] S1. Add the plate-shaped corundum particles, α-alumina micro powder, and dispersed graphite to a mixer and stir for 15 minutes to obtain a premix.

[0091] S2. Add the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide to the mixer and dry mix for 8 minutes. Add phenolic resin and mix for 10 minutes to obtain the mixture.

[0092] S3. Add premixed material to the mixture and mix for 45 minutes. Pour into a mold and press into shape. Let it air dry naturally for 8 hours. Under inert atmosphere protection, put it into a kiln and heat it to 220°C at a rate of 1.5°C / min. Hold for 1.5 minutes. Then heat it to 650°C at a rate of 3°C / min. Hold for 11.5 hours. Finally, cool it down to 220°C at a rate of 2°C / min to obtain the brick blank.

[0093] S4. Soak the brick blanks in asphalt oil for 3.5 hours at a pressure of 1.2 MPa and an oil soaking temperature of 200℃. After removing them, put them back into the kiln and heat them to 450℃ at a rate of 2℃ / min under an inert atmosphere. Hold them at that temperature for 8 hours and let them cool naturally to room temperature.

[0094] Comparative Example 3

[0095] A green refractory and thermal shock resistant converter slag-blocking sliding plate, the raw materials of which include: 650g of tabular corundum particles, 150g of tabular corundum fine powder, 20g of α-alumina micro powder, 80g of zircon mullite, 80g of dispersed graphite, 15g of carbon fiber, 15g of silica micro powder, 15g of titanium powder, 30g of boron nitride, 30g of boron carbide, and 20g of phenolic resin.

[0096] The tabular corundum particles comprise, by mass percentage: 25% tabular corundum particles with a particle size of 0.1-0.5 mm, 25% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder tabular corundum particles with a particle size of 1-3 mm.

[0097] Dispersed graphite was prepared using the following steps: 80g of flake graphite powder was soaked in an 8% hydrofluoric acid solution and stirred at 55℃ for 3 hours. The solution was then filtered, washed, and vacuum dried to obtain pretreated graphite. 10g of ferric nitrate, 10g of urea, 5g of potassium nitrate, and 15g of sodium hexadecyl sulfate were added to 600g of deionized water and stirred at 55℃ for 90 minutes. The pretreated graphite was then added and ultrasonically treated for 90 minutes at a frequency of 55kHz. The solution was then filtered, washed, and vacuum dried.

[0098] The preparation method of the above-mentioned green refractory and thermal shock resistant converter slag-blocking sliding plate includes the following steps:

[0099] S1. Add the plate-shaped corundum particles, α-alumina micro powder, and dispersed graphite into a mixer and stir for 15 minutes to obtain a premix.

[0100] S2. Add the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide to the mixer and dry mix for 8 minutes. Then add phenolic resin and mix for 10 minutes to obtain the mixture.

[0101] S3. Add premixed material to the mixture and mix for 45 minutes. Pour into a mold and press into shape. Let it air dry naturally for 8 hours. Under inert atmosphere protection, put it into a kiln and heat it to 220°C at a rate of 1.5°C / min. Hold for 1.5 minutes. Then heat it to 650°C at a rate of 3°C / min. Hold for 11.5 hours. Finally, cool it down to 220°C at a rate of 2°C / min to obtain the brick blank.

[0102] S4. Soak the brick blanks in asphalt oil for 3.5 hours at a pressure of 1.2 MPa and an oil soaking temperature of 200℃. After removing them, put them back into the kiln and heat them to 450℃ at a rate of 2℃ / min under an inert atmosphere. Hold them at that temperature for 8 hours and let them cool naturally to room temperature.

[0103] The room temperature compressive strength of the converter slag-blocking sliding plates obtained in Example 5 and Comparative Examples 1-3 was determined according to GB / T 5072-2023 "Test Method for Room Temperature Compressive Strength of Refractory Materials". The high temperature (1350℃) compressive strength of the converter slag-blocking sliding plates obtained in Example 5 and Comparative Examples 1-3 was determined according to GB / T 34218-2017 "Test Method for High Temperature Compressive Strength of Refractory Materials".

[0104] like Figure 1 As shown, the slide plate for converter slag blocking obtained in Example 5 has the highest room temperature compressive strength and high temperature compressive strength, which is significantly better than that of Comparative Examples 1-3.

[0105] The high-temperature (1500℃) flexural strength of the converter slag-blocking sliding plates obtained in Example 5 and Comparative Examples 1-3 was determined according to GB / T 3002-2017 "Test Method for High-Temperature Flexural Strength of Refractory Materials". The thermal shock stability (1100℃, characterized by the number of water cooling cycles) of the converter slag-blocking sliding plates obtained in Example 5 and Comparative Examples 1-3 was determined according to Method 1 (Water Quenching Method - Straight Brick Sample) in GB / T 30873-2014 "Test Method for Thermal Shock Resistance of Refractory Materials".

[0106] like Figure 2 As shown, the high-temperature flexural strength of the converter slag-blocking sliding plate obtained in Example 5 is the highest, and the number of water-cooling cycles for thermal shock stability is the most, which is significantly better than that of Comparative Examples 1-3.

[0107] The apparent porosity of the converter slag-blocking sliding plates obtained in Example 5 and Comparative Examples 1-3 was determined according to GB / T 2997-2015 "Test Methods for Bulk Density, Apparent Porosity and True Porosity of Dense Shaped Refractory Products". The oxidation resistance of the converter slag-blocking sliding plates obtained in Example 5 and Comparative Examples 1-3 was determined according to GB / T 17732-2023 "Test Methods for Dense Shaped Carbon-Containing Refractory Products".

[0108] like Figure 3 As shown, the apparent porosity of the converter slag-blocking slide plate obtained in Example 5 is moderate; and its oxidation resistance is the strongest, significantly better than that of Comparative Examples 1-3.

[0109] The reasons for the above results are as follows: This invention uses a compound of plate-shaped corundum particles, α-alumina micro powder, and dispersed graphite, which have high dispersion uniformity. During the high-temperature treatment in the kiln, the urea, potassium nitrate, and ferric nitrate intercalated in the dispersed graphite decompose to form gases, which promote the formation of high pressure between the graphite layers and cause the graphite flakes to open along the basal plane. In the thermal shock environment, it can effectively absorb and disperse stress, significantly alleviate the hot damage of the slide plate. Iron can also form nanocrystals with carbon as structural support, significantly enhancing the compressive strength. This invention uses dispersed graphite with a high specific surface area to be compounded with silicon micro powder and titanium powder. Silicon micro powder reacts with carbon to form a silicon carbide ceramic phase, while titanium powder reacts with carbon and nitrogen to form a titanium carbonitride ceramic phase. Boron nitride acts as a seed crystal to promote the formation of non-oxide ceramic phases, forming a dense ceramic network. Under high pressure, the silicon carbide ceramic phase and the titanium carbonitride ceramic phase provide rigid support, and the layered structure of graphite dissipates energy through plastic deformation. The two work together to resist the erosion of steel slag. Meanwhile, the high dispersibility of dispersed graphite optimizes the particle interface bonding, reduces stress concentration points, and significantly improves the overall high-temperature flexural strength.

[0110] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A green refractory heat shock resistant slide gate for a converter, characterized in that, The raw materials, by weight, include: 50-80 parts of tabular corundum particles, 10-20 parts of fine tabular corundum powder, 1-3 parts of α-alumina micro powder, 5-10 parts of zircon mullite, 5-10 parts of dispersed graphite, 1-2 parts of carbon fiber, 1-2 parts of silica micro powder, 1-2 parts of titanium powder, 1-5 parts of boron nitride, 1-5 parts of boron carbide, and 1-3 parts of phenolic resin. The raw materials for dispersed graphite include: flake graphite powder, ferric nitrate, urea, potassium nitrate, and surfactant; the mass ratio of flake graphite powder, ferric nitrate, urea, potassium nitrate, and surfactant is 5-10:1-3:1-3:1-2:1-2; Dispersed graphite is prepared by the following steps: flake graphite powder is soaked in hydrofluoric acid solution and stirred at 50-60℃ for 2-4 hours, filtered, washed, and vacuum dried to obtain pretreated graphite; ferric nitrate, urea, potassium nitrate, and surfactant are added to water and stirred at 50-60℃ for 1-2 hours, then the pretreated graphite is added and ultrasonically treated for 1-2 hours, filtered, washed, and vacuum dried.

2. The green refractory slidegate plate according to claim 1, wherein The tabular corundum particles, by mass percentage, comprise: 20-30% tabular corundum particles with a particle size of 0.1-0.5 mm, 20-30% tabular corundum particles with a particle size of 0.5-1 mm, and the remainder being tabular corundum particles with a particle size of 1-3 mm.

3. The green refractory slide gate plate according to claim 1, wherein The particle size of the tabular corundum fine powder is 0.01-0.1 mm.

4. The green refractory slidegate plate according to claim 1, wherein The grain size of zircon mullite is 0.5-1 mm.

5. The green refractory slidegate plate according to claim 1, wherein The hydrofluoric acid solution has a mass fraction of 5-10%, and the surfactant is sodium hexadecyl sulfate.

6. The green refractory slidegate plate of claim 1, wherein The ultrasonic frequency is 50-60kHz.

7. A method of manufacturing a green refractory thermal shock resistant slide gate plate for a converter as claimed in any one of claims 1 to 6, characterised in that, Includes the following steps: S1. Stir the tabular corundum particles, α-alumina micro powder, and dispersed graphite for 10-20 minutes to obtain a premix; S2. Dry mix the plate-shaped corundum fine powder, zircon mullite, carbon fiber, silicon micro powder, titanium powder, boron nitride, and boron carbide for 5-10 minutes, then add phenolic resin and mix for 5-15 minutes to obtain the compound. S3. Add premixed material to the mixture and mix for 30-60 minutes. Pour into a mold and press into shape. Let it air dry naturally for 5-10 hours. Under an inert atmosphere, heat to 190-250℃ and hold for 1-2 minutes. Then heat to 600-700℃ and hold for 10-13 hours. Finally, cool to 200-250℃ to obtain a brick blank. S4. Soak the brick blanks in oil for 2-5 hours, then remove them and put them back into the kiln. Under an inert atmosphere, heat the kiln to 400-500℃, keep it at that temperature for 5-10 hours, and then let it cool naturally to room temperature.

8. The method for preparing the sliding plate for slag blocking in a green refractory and thermal shock resistant converter according to claim 7, characterized in that, In S3, the heating rate is 1-2℃ / min during the process of heating to 190-250℃; the heating rate is 2-4℃ / min during the process of heating to 600-700℃; and the cooling rate is 1-3℃ / min during the process of cooling down to 200-250℃.

9. The method for preparing the green refractory and thermal shock resistant converter slag-blocking sliding plate according to claim 7, characterized in that, In S4, the heating rate is 1-3℃ / min during the process of heating to 400-500℃.

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