In-situ spinel reinforced ca2mg2al 28 O 46 Ceramic filter and method of making same

Abstract

This invention discloses an in-situ generated spinel-reinforced Ca2Mg2Al 28 O 46 Ceramic filter and its preparation method; the method includes the following steps: S1, Ca2Mg2Al 28 O 46 S1. Powder, nano-α-Al2O3 powder, and nano-MgO powder are stirred and mixed to obtain raw material powder; S2. Dispersant, thickener, binder, and water are added to the raw material powder and mixed evenly to obtain raw material slurry; S3. A polyurethane mesh porous template is immersed in the raw material slurry for coating, and dried to obtain green body; S4. The green body is sintered under carbon embedding conditions, and Ca2Mg2Al is added during the sintering process. 28 O 46 Powder formation Ca2Mg2Al 28 O 46 In ceramics, nano-α-Al₂O₃ powder and nano-MgO powder undergo an in-situ chemical reaction to generate spinel, which fills the ceramic matrix, ultimately resulting in spinel-reinforced Ca₂Mg₂Al₂O₃. 28 O 46 Ceramic filter. In-situ generated spinel-reinforced Ca2Mg2Al. 28 O 46 The compressive strength at room temperature and high temperature, thermal shock resistance, and resistance to molten metal erosion of ceramic filters have all been significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of high-quality clean steel production technology, specifically relating to in-situ generation of spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filters and their preparation methods. Background Technology

[0002] Mesh ceramic filters, as a key type of functional refractory material, are widely used in the efficient removal process of non-metallic inclusions in molten steel due to their unique three-dimensional interconnected mesh structure, high porosity, and excellent high-temperature chemical and mechanical stability. They can significantly improve the purity of molten steel and have vital theoretical and engineering value for breaking through the core technical bottlenecks in the production of high-quality clean steel and promoting the high-quality development of the metallurgical industry.

[0003] Patent document CN120664897A discloses a "method for preparing a novel ceramic filter for casting nickel-based superalloy melts", which successfully prepared a novel Ca2Mg2Al filter using an organic impregnation method. 28 O 46 Ceramic filters. This preparation method has the advantages of low cost, high purification efficiency and simple process, and is considered a highly promising preferred technology route in the field of industrial filter material preparation.

[0004] However, novel Ca2Mg2Al prepared by organic impregnation method 28 O 46 Ceramic filters face at least the following pressing technical challenges: First, the manufacturing process easily leads to the formation of hollow pore structures; second, the high-temperature pyrolysis combustion of the polymer template introduces numerous defects such as pores and microcracks into the ceramic matrix. These problems directly result in low mechanical strength at both room and high temperatures, insufficient thermal shock resistance, and consequently severely weaken the structural integrity, thermal shock resistance, and resistance to molten metal erosion of the ceramic material, limiting its practical application in high-temperature steelmaking environments. Summary of the Invention

[0005] In view of this, on the one hand, some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 The preparation method of the ceramic filter includes the following steps:

[0006] S1, Ca2Mg2Al 28 O 46 The raw material powder is obtained by stirring and mixing powder, nano α-Al2O3 powder and nano MgO powder;

[0007] S2. Add dispersant, thickener, binder and water to the raw material powder, and mix evenly to obtain raw material slurry;

[0008] S3. A polyurethane mesh porous template is immersed in the raw material slurry for coating, and then dried to obtain a green body.

[0009] S4. The green body is heated and sintered under carbon-embedded conditions. During the sintering process, Ca2Mg2Al 28 O 46 Powder formation Ca2Mg2Al 28 O 46 In ceramics, nano-α-Al₂O₃ powder and nano-MgO powder undergo an in-situ chemical reaction to generate spinel, which fills the ceramic matrix, ultimately resulting in spinel-reinforced Ca₂Mg₂Al₂O₃. 28 O 46 Ceramic filter.

[0010] Furthermore, some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 In the preparation method of ceramic filters, in step S1, the raw material powder contains Ca2Mg2Al 28 O 46 The powder content is 90-99 wt%, the nano α-Al2O3 powder content is 0.5-5 wt%, and the nano MgO powder content is 0.5-5 wt%.

[0011] Some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 In the preparation method of the ceramic filter, in step S1, the stirring speed is 200-1000 r / min and the stirring time is 2-10 min.

[0012] Some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 In the preparation method of the ceramic filter, in step S2, the raw material slurry contains 55-79.3% raw material powder, 0.1-1.0 wt% dispersant, 0.1-1.0 wt% thickener, 0.5-3.0 wt% binder, and the balance is water.

[0013] Some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 The method for preparing a ceramic filter, step S2 includes:

[0014] Add dispersant, thickener and binder to the raw material powder and stir evenly. The stirring speed is 200-1000 r / min and the stirring time is 2-10 min.

[0015] Add water and stir further until homogeneous. The stirring speed is 800-1500 r / min and the stirring time is 10-30 min to obtain the raw material slurry.

[0016] Some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 The method for preparing a ceramic filter, step S3 includes:

[0017] S31. The polyurethane mesh porous plate is subjected to slurry coating, slurry extrusion, and drying to obtain the first preform; specifically, the polyurethane mesh porous template is immersed in the raw material slurry to ensure full slurry coating; after slurry coating, the polyurethane mesh porous template is removed and subjected to slurry extrusion using a roller mill to remove excess raw material slurry, with the roller spacing being 8-20% of the height of the polyurethane mesh porous template; and dried by blowing hot air at 25-60℃ for 1-5 minutes to obtain the first preform.

[0018] S32. The first preform is subjected to slurry coating-slurry extrusion-drying according to the process of step S31 to obtain the second preform;

[0019] S33. The second preform is subjected to slurry coating and extrusion according to the process of S31, and is naturally air-dried for 24 hours to obtain the green body.

[0020] Some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 The method for preparing a ceramic filter, step S4 includes:

[0021] The green body was heated to a sintering temperature of 1550–1700°C at a heating rate of 1–10°C / min under carbon embedding conditions, and held at the sintering temperature for 1–5 hours. The green body was then cooled in the furnace to obtain spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

[0022] Some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 The method for preparing a ceramic filter, step S4 includes:

[0023] The green body is heated to 200-700℃ at a heating rate of 1-3℃ / min under carbon-embedded conditions and held for 1-2 hours; then heated to a sintering temperature of 1550-1700℃ at a heating rate of 3-5℃ / min and held for 1-2 hours; cooling yields spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

[0024] Some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al28 O 46 The method for preparing the ceramic filter, step S3 further includes a pretreatment step of the polyurethane mesh porous plate, specifically including: soaking the polyurethane mesh porous template in a NaOH aqueous solution with a mass content of 5-30% for 1-5 hours, and then washing it with water.

[0025] On the other hand, some embodiments disclose an in-situ generated spinel-reinforced Ca2Mg2Al 28 O 46 The ceramic filter is made of in-situ generated spinel-reinforced Ca2Mg2Al as disclosed in the embodiments of the present invention. 28 O 46 The method for preparing ceramic filters was obtained, with spinel-reinforced Ca2Mg2Al. 28 O 46 The ceramic filter has a porosity of 80-90%, a room temperature compressive strength of 1.5-3.5 MPa, and a residual compressive strength retention rate of 65-85%.

[0026] The in-situ generated spinel-reinforced Ca2Mg2Al disclosed in this invention embodiment 28 O 46 The preparation method of ceramic filters, using Ca2Mg2Al 28 O 46 Using powder, nano-α-Al₂O₃ powder, and nano-MgO powder as raw materials, a spinel-reinforced ceramic filter was successfully prepared via a process route of one-time batching, multiple slurry coating, and one-step carbon embedding sintering. During the sintering process, nano-α-Al₂O₃ and nano-MgO in the raw material system undergo an in-situ chemical reaction to generate spinel, effectively filling Ca₂Mg₂Al₂O₃. 28 O 46 The cracks and hollow pores in the ceramic matrix enable the control of Ca2Mg2Al 28 O 46 Microscopic control of defects in ceramic matrix; the reducing atmosphere created by the embedded carbon sintering process not only provides suitable thermodynamic and kinetic conditions for spinel nucleation and directional growth, but also effectively inhibits Ca2Mg2Al 28 O 46 High-temperature oversintering of the ceramic matrix. The prepared spinel-reinforced Ca2Mg2Al... 28 O 46 The compressive strength, thermal shock resistance, and molten metal erosion resistance of ceramic filters at both room temperature and high temperature are significantly improved. The process is simple, highly controllable, and inexpensive, showing promising application prospects in the field of ceramic filters for clean steel production technology. Attached Figure Description

[0027] Figure 1 , oneSome embodiments disclose in-situ generated spinel-reinforced Ca2Mg2Al 28 O 46 Flowchart of ceramic filter preparation method;

[0028] Figure 2 Example 1 discloses spinel-reinforced Ca2Mg2Al 28 O 46 SEM image of a ceramic filter. Detailed Implementation

[0029] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in these embodiments of the invention, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in these embodiments is merely for describing particular implementations and is not intended to limit the scope of the disclosure of these embodiments.

[0030] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain; other experimental methods and technical means not specifically noted in the embodiments of this invention refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0031] The terms “basic” and “approximately” as used herein are used to describe small fluctuations. For example, they can mean less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Numerical data presented or expressed in range format herein are used for convenience and brevity only, and should therefore be interpreted flexibly to include not only the explicitly listed values ​​that define the range, but also all independent values ​​or subranges contained within that range. For example, a numerical range of “1–5%” should be interpreted to include not only the explicitly listed values ​​from 1% to 5%, but also the independent values ​​and subranges within the indicated range. Thus, this numerical range includes independent values ​​such as 2%, 3.5%, and 4%, and subranges such as 1%–3%, 2%–4%, and 3%–5%, etc. This principle also applies to ranges that list only one value. Furthermore, this interpretation applies regardless of the width of the range or the characteristics described.

[0032] In this document, including in the claims, conjunctions such as "comprising," "including," "with," "having," "containing," "involving," and "accommodating" are understood to be open-ended, meaning "including but not limited to." Only the conjunctions "consisting of" and "composed of" are closed conjunctions.

[0033] To better illustrate the content of this invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the invention can be practiced even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail, in order to highlight the main points of the invention.

[0034] Without conflict, the technical features disclosed in the embodiments of the present invention can be combined arbitrarily, and the resulting technical solutions belong to the content disclosed in the embodiments of the present invention.

[0035] In some implementations, such as Figure 1 As shown, the in-situ generation method for preparing spinel-reinforced Ca2Mg2Al28O46 ceramic filters includes the following steps:

[0036] S1, Ca2Mg2Al 28 O 46 The raw material powder is obtained by stirring and mixing powder, nano-α-Al₂O₃ powder, and nano-MgO powder. Typically, the powder raw materials are mixed under mechanical stirring to obtain a uniformly mixed raw material powder. The stirring speed is usually set to 200–1000 r / min, and the stirring time is set to 2–10 min. Typically, the raw material powder contains Ca₂Mg₂Al₂O₃ powder. 28 O 46 The powder content is 90–99 wt%, the nano α-Al₂O₃ powder content is 0.5–5 wt%, and the nano MgO powder content is 0.5–5 wt%.

[0037] In some embodiments, Ca2Mg2Al 28 O 46 The particle size of the powder raw material is ≤20μm, Ca2Mg2Al 28 O 46 Ca2Mg2Al in powder raw materials 28 O 46 The mass content is ≥95wt%; the particle size of the nano α-Al2O3 powder raw material is ≤100nm, and the α-Al2O3 content in the nano α-Al2O3 powder raw material is ≥98wt%; the particle size of the selected nano MgO powder raw material is ≤100nm, and the MgO content in the nano MgO powder raw material is ≥97wt%;

[0038] S2. Dispersant, thickener, binder and water are added to the raw material powder and mixed evenly to obtain a raw material slurry; typically, the raw material slurry contains 55-79.3% raw material powder by mass, 0.1-1.0 wt% dispersant by mass, 0.1-1.0 wt% thickener by mass, 0.5-3.0 wt% binder by mass, and the balance is water;

[0039] In some embodiments, polycarboxylate is used as a dispersant; carboxymethyl cellulose is used as a thickener; and ammonium lignosulfonate is used as a binder.

[0040] In some embodiments, a dispersant, thickener, and binder are added to the raw material powder and stirred evenly at a stirring speed of 200–1000 r / min for 2–10 min; water is then added and stirred evenly at a stirring speed of 800–1500 r / min for 10–30 min to obtain a raw material slurry.

[0041] S3. The polyurethane mesh porous template is immersed in the raw material slurry for coating and dried to obtain a green body; usually, it also includes a pretreatment step of the polyurethane mesh porous board, specifically including: soaking the polyurethane mesh porous template in a NaOH aqueous solution with a mass content of 5-30% for 1-5 hours, then washing with water and air-drying; usually, the pore size of the polyurethane mesh porous template is 9, 15 or 20 ppi.

[0042] In some embodiments, the preparation process of the green body in step 3 includes:

[0043] S31. The polyurethane mesh porous plate is subjected to slurry coating, slurry extrusion, and drying to obtain the first preform; specifically, the polyurethane mesh porous template is immersed in the raw material slurry to ensure full slurry coating; after slurry coating, the polyurethane mesh porous template is removed and subjected to slurry extrusion using a roller mill to remove excess raw material slurry, with the roller spacing being 8-20% of the height of the polyurethane mesh porous template; and then dried by blowing hot air at 25-60℃ for 1-5 minutes to obtain the first preform.

[0044] S32. The first preform is subjected to slurry coating-slurry extrusion-drying according to the process of step S31 to obtain the second preform;

[0045] S33. The second preform is subjected to slurry coating and extrusion according to the process of S31, and is naturally air-dried for 24 hours to obtain the green body.

[0046] S4. The green body is heated and sintered under carbon-embedded conditions. During the sintering process, Ca2Mg2Al 28 O 46 Powder formation Ca2Mg2Al 28 O 46 In ceramics, nano-α-Al₂O₃ powder and nano-MgO powder undergo an in-situ chemical reaction to generate spinel, which fills the ceramic matrix, ultimately resulting in spinel-reinforced Ca₂Mg₂Al₂O₃. 28 O 46 Ceramic filters. Typically, during the sintering process, nano-α-Al₂O₃ powder and nano-MgO powder in the raw material powder system undergo an in-situ chemical reaction to generate spinel, effectively filling the Ca₂Mg₂Al₂O₃ mixture. 28 O 46The cracks and hollow pores in the ceramic matrix enable the control of Ca2Mg2Al 28 O 46 Microscopic control of defects in ceramic matrix; the reducing atmosphere created by the embedded carbon sintering process not only provides suitable thermodynamic and kinetic conditions for spinel nucleation and directional growth, but also effectively inhibits Ca2Mg2Al 28 O 46 High-temperature over-sintering of the ceramic matrix.

[0047] Generally, carbon embedding conditions refer to the general term for process conditions achieved by placing the green sample in a closed / semi-closed environment containing carbon media throughout the sintering process. The core purpose is to create a reducing / weakly reducing atmosphere, control the carbon reduction reaction rate, and at the same time avoid oxidation of the green sample, so as to ensure the smooth progress of the carbothermic reduction reaction to form spinel.

[0048] In some embodiments, the green sintering process in step S4 includes: heating the green under carbon-embedded conditions to a sintering temperature of 1550–1700°C at a heating rate of 1–10°C / min, holding at the sintering temperature for 1–5 hours, and then cooling in the furnace to obtain spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

[0049] In some embodiments, the green sintering process in step S4 includes:

[0050] The green body is heated to 200-700℃ at a heating rate of 1-3℃ / min under carbon-embedded conditions and held for 1-2 hours. Generally, during the heating process to 200-700℃, especially in the temperature range of 0-600℃, free moisture and organic polymers will be removed. During this process, a slow heating rate of 1-3℃ / min and holding at 200-700℃ for a period of time is conducive to the full removal of moisture and polymers. If the heating is too rapid, it may cause the product to collapse. At the same time, it can also allow the carbon source to react fully with the residual oxygen in the furnace, create a reducing atmosphere in advance, and avoid early oxidation of the sample.

[0051] Then, heat to a sintering temperature of 1550-1700℃ at a heating rate of 3-5℃ / min, and hold at the sintering temperature for 1-2 hours; cool down to obtain spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

[0052] Some embodiments disclose in-situ generation of spinel-reinforced Ca2Mg2Al 28 O 46 The ceramic filter is made of in-situ generated spinel-reinforced Ca2Mg2Al as disclosed in the embodiments of the present invention. 28 O 46A method for preparing ceramic filters was used, which involved spinel-reinforced Ca2Mg2Al. 28 O 46 The ceramic filter has a porosity of 80-90%, a room temperature compressive strength of 1.5-3.5 MPa, and a residual compressive strength retention rate of 65-85%. In simulated molten steel filtration tests, the filtration efficiency for non-metallic inclusions in molten steel is 75-90%.

[0053] The technical details are further illustrated below with reference to the embodiments.

[0054] Example 1

[0055] In Example 1, spinel was generated in situ to reinforce Ca2Mg2Al. 28 O 46 Methods for preparing ceramic filters include:

[0056] By mass, 98 parts Ca2Mg2Al 28 O 46 The first raw material powder is obtained by mechanically mixing Ca2Mg2Al powder, 1 part nano α-Al2O3 powder, and 1 part nano MgO powder; wherein, Ca2Mg2Al 28 O 46 The powder has a particle size of 20 μm, Ca2Mg2Al 28 O 46 Ca2Mg2Al in powder 28 O 46 The content of α-Al2O3 is 99wt%; the particle size of nano α-Al2O3 powder is 30nm, and the content of α-Al2O3 in nano α-Al2O3 powder is ≥98wt%; the particle size of nano MgO powder is 30nm, and the content of MgO in nano MgO powder is 97wt%; the mechanical stirring speed is 300r / min, and the mixing time is 5min;

[0057] 72 parts of the first raw material powder, 0.3 parts of dispersant polycarboxylate, 0.5 parts of thickener carboxymethyl cellulose, and 1.0 parts of binder ammonium lignosulfonate were selected and mechanically mixed at a speed of 300 r / min for 5 min to obtain the second raw material powder.

[0058] Add 28 parts of water to the second raw material powder and continue mechanical stirring at a speed of 1000 r / min for 15 min to obtain the raw material slurry;

[0059] A 15ppi polyurethane mesh porous template was pretreated by soaking it in a 10% NaOH aqueous solution for 4 hours.

[0060] The raw material slurry is immersed in the pretreated polyurethane mesh porous template, and the porous template is squeezed to remove air, so that the raw material slurry is completely filled into the porous template and fully coated with slurry; the slurry is squeezed by a roller extruder with the roller gap being 10% of the height of the polyurethane mesh porous template; the surface is dried slightly by blowing hot air at 60℃ for 1 to 2 minutes to obtain the first preform.

[0061] According to the above-described process conditions for preparing the first preform, the first preform is impregnated, extruded, and dried again to obtain the second preform;

[0062] Referring to the above-mentioned process conditions for preparing the first preform, the second preform was impregnated-extruded and then naturally air-dried for 24 hours to obtain a green body;

[0063] The resulting green body was heated from room temperature to 600℃ at a rate of 1℃ / min and held for 1 hour under carbon-embedded conditions, then heated to 1600℃ at a rate of 5℃ / min and held for 2 hours, followed by furnace cooling to obtain spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

[0064] like Figure 2 As shown, spinel-reinforced Ca2Mg2Al 28 O 46 In ceramic filters, Ca2Mg2Al 28 O 46 The ceramic matrix is ​​filled with a discretely distributed spinel phase; upon testing, the spinel-reinforced Ca2Mg2Al prepared in Example 1... 28 O 46 The ceramic filter has a porosity of 82.5%, a room temperature compressive strength of 2.23 MPa, and a residual compressive strength retention rate of 78.4%. In a simulated molten steel filtration test, the filtration efficiency for non-metallic inclusions in the molten steel was 81.9%.

[0065] The simulated molten steel filtration test in Example 1 included: placing a first crucible with an outer diameter of 40 mm inside a graphite crucible, then placing a second crucible with an outer diameter of 30 mm inside the first crucible with an outer diameter of 40 mm. The ceramic filter sample obtained in Example 1 was placed inside the second crucible, and the steel alloy sample was placed on top of the ceramic filter sample. The graphite crucible was placed inside a vacuum induction furnace. The vacuum induction furnace was evacuated to 20 Pa, and then Ar was introduced to maintain the pressure gauge at approximately -0.8 Pa. Subsequently, the vacuum induction furnace was heated to 1600 °C, and molten steel, completely melted from the steel alloy sample, dripped from the ceramic filter sample. Finally, the vacuum induction furnace was turned off and cooled to room temperature. The filtration efficiency of the ceramic filter sample for non-metallic inclusions in the molten steel was found to be 81.9%.

[0066] Example 2

[0067] In Example 2, spinel-reinforced Ca2Mg2Al was generated in situ. 28 O 46 Methods for preparing ceramic filters include:

[0068] By mass, 96 parts Ca2Mg2Al 28 O 46 The first raw material powder was obtained by mechanically mixing Ca2Mg2Al powder, 2 parts of nano α-Al2O3 powder, and 2 parts of nano MgO powder; wherein, Ca2Mg2Al 28 O 46 The powder has a particle size of 20 μm, Ca2Mg2Al 28 O 46 Ca2Mg2Al in powder 28 O 46 The content of α-Al2O3 is 99wt%; the particle size of nano α-Al2O3 powder is 30nm, and the content of α-Al2O3 in nano α-Al2O3 powder is ≥98wt%; the particle size of nano MgO powder is 30nm, and the content of MgO in nano MgO powder is 97wt%; the mechanical stirring speed is 300r / min, and the mixing time is 5min;

[0069] 72 parts of the first raw material powder, 0.3 parts of dispersant polycarboxylate, 0.5 parts of thickener carboxymethyl cellulose, and 1.0 parts of binder ammonium lignosulfonate were selected and mechanically mixed at a speed of 300 r / min for 5 min to obtain the second raw material powder.

[0070] Add 28 parts of water to the second raw material powder and continue mechanical stirring at a speed of 1000 r / min for 15 min to obtain the raw material slurry;

[0071] A 15ppi polyurethane mesh porous template was pretreated by soaking it in a 10% NaOH aqueous solution for 4 hours.

[0072] The raw material slurry is immersed in the pretreated polyurethane mesh porous template, and the porous template is squeezed to remove air, so that the raw material slurry is completely filled into the porous template and fully coated with slurry; the slurry is squeezed by a roller extruder with the roller gap being 10% of the height of the polyurethane mesh porous template; the surface is dried slightly by blowing hot air at 60℃ for 1 to 2 minutes to obtain the first preform.

[0073] According to the above-described process conditions for preparing the first preform, the first preform is impregnated, extruded, and dried again to obtain the second preform;

[0074] Referring to the above-mentioned process conditions for preparing the first preform, the second preform was impregnated-extruded and then naturally air-dried for 24 hours to obtain a green body;

[0075] The resulting green body was heated from room temperature to 600℃ at a rate of 1℃ / min and held for 1 hour under carbon-embedded conditions, then heated to 1600℃ at a rate of 5℃ / min and held for 2 hours, followed by furnace cooling to obtain spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

[0076] Testing revealed that the spinel-reinforced Ca2Mg2Al prepared in Example 2... 28 O 46 The ceramic filter has a porosity of 81.1%, a room temperature compressive strength of 2.57 MPa, and a residual compressive strength retention rate of 80.3%. In a simulated molten steel filtration test, the filtration efficiency for non-metallic inclusions in the molten steel was 84.6%.

[0077] Comparative Example 1

[0078] In Comparative Example 1, Ca2Mg2Al 28 O 46 Methods for preparing ceramic filters include:

[0079] With Ca2Mg2Al 28 O 46 The powder is the first raw material powder; among which, Ca2Mg2Al 28 O 46 The powder has a particle size of 20 μm, Ca2Mg2Al 28 O 46 Ca2Mg2Al in powder 28 O 46 The content is 99 wt%;

[0080] 72 parts of the first raw material powder, 0.3 parts of dispersant polycarboxylate, 0.5 parts of thickener carboxymethyl cellulose, and 1.0 parts of binder ammonium lignosulfonate were selected and mechanically mixed at a speed of 300 r / min for 5 min to obtain the second raw material powder.

[0081] Add 28 parts of water to the second raw material powder and continue mechanical stirring at a speed of 1000 r / min for 15 min to obtain the raw material slurry;

[0082] A 15ppi polyurethane mesh porous template was pretreated by soaking it in a 10% NaOH aqueous solution for 4 hours.

[0083] The raw material slurry is immersed in the pretreated polyurethane mesh porous template, and the porous template is squeezed to remove air, so that the raw material slurry is completely filled into the porous template and fully coated with slurry; the slurry is squeezed by a roller extruder with the roller gap being 10% of the height of the polyurethane mesh porous template; the surface is dried slightly by blowing hot air at 60℃ for 1 to 2 minutes to obtain the first preform.

[0084] According to the above-described process conditions for preparing the first preform, the first preform is impregnated, extruded, and dried again to obtain the second preform;

[0085] Referring to the above-mentioned process conditions for preparing the first preform, the second preform was impregnated-extruded and then naturally air-dried for 24 hours to obtain a green body;

[0086] The resulting green body was heated from room temperature to 600℃ at a rate of 1℃ / min and held for 1 hour under carbon-embedded conditions, then heated to 1600℃ at a rate of 5℃ / min and held for 2 hours, followed by furnace cooling to obtain spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

[0087] Testing revealed that the Ca2Mg2Al prepared in Comparative Example 1... 28 O 46 The ceramic filter has a porosity of 83.9%, a room temperature compressive strength of 1.53 MPa, and a residual compressive strength retention rate of 38.4%. In a simulated molten steel filtration test, the filtration efficiency for non-metallic inclusions in the molten steel was 66%.

[0088] The in-situ generated spinel-reinforced Ca2Mg2Al disclosed in this invention embodiment 28 O 46 The preparation method of ceramic filters, using Ca2Mg2Al 28 O 46 Using powder, nano-α-Al₂O₃ powder, and nano-MgO powder as raw materials, a spinel-reinforced ceramic filter was successfully prepared via a process route of one-time batching, multiple slurry coating, and one-step carbon embedding sintering. During the sintering process, the nano-α-Al₂O₃ powder and nano-MgO in the raw material system undergo an in-situ chemical reaction to generate spinel, effectively filling Ca₂Mg₂Al₂O₃. 28 O 46 The cracks and hollow pores in the ceramic matrix enable the control of Ca2Mg2Al 28 O 46 Microscopic control of defects in ceramic matrix; the reducing atmosphere created by the embedded carbon sintering process not only provides suitable thermodynamic and kinetic conditions for spinel nucleation and directional growth, but also effectively inhibits Ca2Mg2Al 28 O 46 High-temperature oversintering of the ceramic matrix. The prepared spinel-reinforced Ca2Mg2Al... 28 O 46 The compressive strength, thermal shock resistance, and molten metal erosion resistance of ceramic filters at both room temperature and high temperature are significantly improved. The process is simple, highly controllable, and inexpensive, showing promising application prospects in the field of ceramic filters for clean steel production technology.

[0089] The technical solutions and technical details disclosed in the embodiments of this invention are merely illustrative of the inventive concept of this invention and do not constitute a limitation on the technical solutions of the embodiments of this invention. Any conventional changes, substitutions, or combinations made to the technical details disclosed in the embodiments of this invention have the same inventive concept as this invention and are within the protection scope of the claims of this invention.

Claims

1. In-situ formation of spinel to enhance Ca2Mg2Al 28 O 46 A method for preparing a ceramic filter, characterized in that, Including the following steps: S1, Ca2Mg2Al 28 O 46 The raw material powder is obtained by stirring and mixing powder, nano α-Al2O3 powder and nano MgO powder; S2. Add dispersant, thickener, binder and water to the raw material powder, and mix evenly to obtain raw material slurry; S3. A polyurethane mesh porous template is immersed in the raw material slurry for coating, and then dried to obtain a green body. S4. The green body is heated and sintered under carbon-embedded conditions. During the sintering process, Ca2Mg2Al 28 O 46 Powder formation Ca2Mg2Al 28 O 46 In ceramics, nano-α-Al₂O₃ powder and nano-MgO powder undergo an in-situ chemical reaction to generate spinel, which fills the ceramic matrix, ultimately resulting in spinel-reinforced Ca₂Mg₂Al₂O₃. 28 O 46 Ceramic filter.

2. The in-situ generated spinel-reinforced Ca2Mg2Al according to claim 1 28 O 46 A method for preparing a ceramic filter, characterized in that, In step S1, the raw material powder contains Ca2Mg2Al 28 O 46 The powder content is 90-99 wt%, the nano α-Al2O3 powder content is 0.5-5 wt%, and the nano MgO powder content is 0.5-5 wt%.

3. The in-situ generated spinel-reinforced Ca2Mg2Al according to claim 1 28 O 46 A method for preparing a ceramic filter, characterized in that, In step S1, the stirring speed is 200-1000 r / min and the stirring time is 2-10 min.

4. The in-situ generated spinel-reinforced Ca2Mg2Al according to claim 1 28 O 46 A method for preparing a ceramic filter, characterized in that, In step S2, the raw material slurry contains 55-79.3% raw material powder, 0.1-1.0 wt% dispersant, 0.1-1.0 wt% thickener, 0.5-3.0 wt% binder, and the remainder is water.

5. The in-situ generated spinel-reinforced Ca2Mg2Al according to claim 1 28 O 46 A method for preparing a ceramic filter, characterized in that, Step S2 includes: Add dispersant, thickener and binder to the raw material powder and stir evenly. The stirring speed is 200-1000 r / min and the stirring time is 2-10 min. Add water and stir further until homogeneous. The stirring speed is 800-1500 r / min and the stirring time is 10-30 min to obtain the raw material slurry.

6. The in-situ generated spinel-reinforced Ca2Mg2Al according to claim 1 28 O 46 A method for preparing a ceramic filter, characterized in that, Step S3 includes: S31. The polyurethane mesh porous plate is subjected to slurry coating, slurry extrusion, and drying to obtain the first preform; specifically, the polyurethane mesh porous template is immersed in the raw material slurry to ensure full slurry coating; after slurry coating, the polyurethane mesh porous template is removed and subjected to slurry extrusion using a roller mill to remove excess raw material slurry, with the roller spacing being 8-20% of the height of the polyurethane mesh porous template; and then dried by blowing hot air at 25-60℃ for 1-5 minutes to obtain the first preform. S32. The first preform is subjected to slurry coating-slurry extrusion-drying according to the process of step S31 to obtain the second preform; S33. The second preform is subjected to slurry coating and extrusion according to the process of S31, and is naturally air-dried for 24 hours to obtain the green body.

7. The in-situ generated spinel-reinforced Ca2Mg2Al according to claim 1 28 O 46 A method for preparing a ceramic filter, characterized in that, Step S4 includes: The green body was heated to a sintering temperature of 1550–1700°C at a heating rate of 1–10°C / min under carbon embedding conditions, and held at the sintering temperature for 1–5 hours. The green body was then cooled in the furnace to obtain spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

8. The in-situ generated spinel-reinforced Ca2Mg2Al according to claim 1 28 O 46 A method for preparing a ceramic filter, characterized in that, Step S4 includes: The green body is heated to 200-700℃ at a heating rate of 1-3℃ / min under carbon-embedded conditions and held for 1-2 hours; then heated to a sintering temperature of 1550-1700℃ at a heating rate of 3-5℃ / min and held for 1-2 hours; cooling yields spinel-reinforced Ca2Mg2Al. 28 O 46 Ceramic filter.

9. The in-situ generated spinel-reinforced Ca2Mg2Al according to claim 1 28 O 46 A method for preparing a ceramic filter, characterized in that, Step S3 also includes a pretreatment step for the polyurethane mesh porous plate, specifically including: soaking the polyurethane mesh porous template in a NaOH aqueous solution with a mass content of 5-30% for 1-5 hours, and then washing it with water.

10. An in-situ generated spinel-reinforced Ca2Mg2Al 28 O 46 Ceramic filter, characterized in that, The in-situ generated spinel-reinforced Ca2Mg2Al according to any one of claims 1 to 9 28 O 46 The method for preparing ceramic filters was obtained, with spinel-reinforced Ca2Mg2Al. 28 O 46 The ceramic filter has a porosity of 80-90%, a room temperature compressive strength of 1.5-3.5 MPa, and a residual compressive strength retention rate of 65-85%.

Images