Doped corrosion-resistant and dioxin-resistant silicon carbide wear-resistant ceramic material

Abstract

The application provides a doped anti-corrosion dioxin-resistant silicon carbide wear-resistant ceramic material, and relates to the technical field of advanced ceramic materials.The material comprises, by weight, 80-95 parts of silicon carbide powder, 1-10 parts of a functional dopant, 2-8 parts of a sintering aid, 2-5 parts of a toughening agent, 0.5-3 parts of a dispersing agent, and 0.5-10 parts of a binder.The core functional dopant is a core-shell structure nano-powder with an anatase TiO2 core and a mixed-valence Ce / Sn silicate shell, which is prepared through sol-gel and heat treatment.The application can successfully endow the material with long-term and stable chemical corrosion resistance and high-temperature catalytic degradation dioxin resistance on the basis of retaining the high strength and high wear resistance of the silicon carbide ceramic, and is suitable for extreme environments such as waste incineration and chemical industry.

Description

Technical Field

[0001] This invention relates to the field of advanced ceramic materials technology, and in particular to a doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material. Background Technology

[0002] Silicon carbide ceramics are widely used in mechanical seals, wear-resistant components, and cutting tools due to their high hardness, high wear resistance, and good thermal and chemical stability. However, in extremely harsh environments such as waste incineration and chemical metallurgy, equipment components not only suffer severe material wear but are also exposed to high temperatures, acidic / alkaline corrosive atmospheres, and persistent organic pollutants such as dioxins for extended periods. While traditional silicon carbide or oxide ceramics are wear-resistant, their resistance to high-temperature corrosion is limited, and they lack the ability to degrade toxic gases, resulting in short component lifespans and potential secondary pollution due to the adsorption or permeation of toxic substances on the material surface.

[0003] While traditional silicon carbide ceramics possess excellent mechanical properties, their functionality is relatively limited, lacking active corrosion resistance and catalytic purification capabilities. Some studies have improved the sintering performance and density of silicon carbide by adding sintering aids (such as Al₂O₃ and Y₂O₃), thereby enhancing its mechanical properties and corrosion resistance to some extent. Other research has attempted to load catalytic components (such as TiO₂) onto the ceramic surface to achieve photocatalytic functions. However, simple surface loading suffers from problems such as easy wear and detachment of the catalytic layer and short lifespan; while directly incorporating catalytic components into the ceramic matrix often leads to deactivation of the catalytic components or damage to the mechanical properties of the ceramic matrix due to high-temperature sintering.

[0004] How to endow silicon carbide ceramics with stable and long-lasting corrosion resistance and dioxin catalytic degradation capabilities without sacrificing their inherent excellent mechanical properties and wear resistance is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the technical challenge of endowing existing silicon carbide ceramics with stable and long-term effective corrosion resistance and dioxin catalytic degradation capabilities while maintaining their inherent excellent mechanical properties and wear resistance, this invention provides a doped, corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material.

[0006] The technical solutions provided by the embodiments of the present invention are as follows:

[0007] The present invention provides a doped corrosion-resistant and dioxin-resistant silicon carbide wear-resistant ceramic material, which, by weight, comprises the following components: silicon carbide powder: 80-95 parts, functional dopant: 1-10 parts, sintering aid: 2-8 parts, toughening agent: 2-5 parts, dispersant: 0.5-3 parts, binder: 0.5-10 parts;

[0008] The preparation method of the functional dopant is as follows:

[0009] (1) Disperse the anatase phase TiO2 nanopowder in a 0.1 mol / L dilute nitric acid solution, sonicate for 1 h, collect by centrifugation, wash twice with deionized water and twice with ethanol, and redisperse the washed TiO2 nanopowder in anhydrous ethanol to prepare an ethanol dispersion with a concentration of about 20 mg / mL.

[0010] (2) Dissolve the metal salt in an ethanol-water mixture (4:1, v / v), stir magnetically for 5-10 min until completely dissolved, and prepare a 3-8 wt% metal salt solution; dissolve tetraethyl orthosilicate (TEOS) in anhydrous ethanol, stir magnetically for 5-10 min until completely dissolved, and prepare a 10-20 wt% silicate ester solution; add concentrated hydrochloric acid to the solution pH=2-4, stir for 4-6 min, and obtain an acid-catalyzed silicate ester solution;

[0011] (3) The metal salt solution is slowly added dropwise to the acid-catalyzed silicate ester solution and mixed evenly. The anatase phase TiO2 nanopowder dispersion is added to the above mixed system. Under nitrogen protection, the temperature is raised to 50-70℃ and the rotation speed is 400-600rpm. 10mL of a mixture of deionized water and anhydrous ethanol in a volume ratio of 1:1 is slowly added dropwise, and the dropping rate is controlled at 1-2 drops / second. The entire dropping process lasts for about 1-2 hours. This process is the key to forming a uniform coating. The slow hydrolysis promotes the uniform nucleation and growth of silicate hydrolysis products on the surface of TiO2 nanocrystals. After the dropping is completed, the temperature is kept constant at 60℃ and the reaction is continued to be stirred for 12-24 hours to allow the coating layer to fully condense and solidify.

[0012] (4) After the reaction is completed, the reaction solution is naturally cooled to room temperature. The solid product is collected using a high-speed centrifuge (10000 rpm, 5-10 min). The product is washed with anhydrous ethanol and deionized water alternately by centrifugation 3-5 times each until the conductivity of the supernatant is close to that of deionized water, so as to completely remove unreacted ions and solvent. The washed product is dried in a vacuum drying oven at 80℃ for 12 h to obtain a primary powder of TiO2 coated with an amorphous layer.

[0013] (5) Place the primary powder in a tube furnace and heat it to 340-360℃ at 1-3℃ / min under a flowing oxygen atmosphere, and hold it for 1-3h to completely decompose the residual organic groups and nitrates. Then switch the atmosphere to nitrogen and heat it to 600-900℃ at 4-6℃ / min, and hold it for 2-4h to transform the amorphous silicate shell into a defective crystalline or microcrystalline state, stabilize the structure, and promote the Ce in the shell under an inert or weakly reducing atmosphere. 4+ Partially restored to Ce 3+ Sn 4+ Partially restored to Sn2+ The desired mixed valence state is formed, which is the core of endowing it with high-temperature redox catalytic activity. After being cooled to room temperature in the furnace, the final functional dopant powder is obtained, which is a core-shell structured nanocomposite powder with an anatase TiO2 core and a crystalline silicate shell containing mixed valence states Ce / Sn.

[0014] Preferably, in the preparation process (1) of the functional dopant, the anatase phase TiO2 nanoparticles have a particle size of 20-50 nm and the ratio of anatase phase TiO2 nanoparticles to concentrated nitric acid is 1 g: 100 ml.

[0015] Preferably, in the preparation process (2) of the functional dopant, the metal salt is at least one of cerium ammonium nitrate, cerium nitrate, stannous chloride, and stannous tetrachloride.

[0016] Preferably, in the preparation process (3) of the functional dopant, the mass ratio of TiO2 to tetraethyl orthosilicate is 1:0.1-0.5, and the molar ratio of metal ions in the metal salt to silicon in tetraethyl orthosilicate is 1:5-100.

[0017] Preferably, the silicon carbide matrix is ​​composed of silicon carbide micro powders of four different particle sizes of 0.1-10μm mixed in a specific ratio, wherein the 0.1-1μm micro powder accounts for 20-30%, the 1-5μm micro powder accounts for 20-30%, the 5-20μm micro powder accounts for 25-27%, and the 20-50μm micro powder accounts for 20-25%.

[0018] Preferably, the sintering aid is a composite of Al2O3 and rare earth oxides, wherein the rare earth oxides are at least one of Y2O3, Sc2O3, and Yb2O3, and the molar ratio of Al2O3 to rare earth oxides is 2.5-3.5:1.5-2.5.

[0019] Preferably, the toughening agent is short-cut carbon fiber or graphene nanosheets.

[0020] Preferably, the dispersant is at least one of polyacrylic acid, sodium polycarboxylate, sodium humate, tetramethylammonium hydroxide, or polyethylene glycol.

[0021] Preferably, the adhesive is at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl methyl cellulose, or polyvinylpyrrolidone.

[0022] A method for preparing the doped corrosion-resistant, dioxin-resistant, and wear-resistant silicon carbide ceramic material includes the following steps:

[0023] S1, Preparation of functional dopants;

[0024] S2. Raw material mixing: Weigh each component according to the weight parts, put the weighed silicon carbide powder, functional dopant, sintering aid, toughening agent and dispersant into a ball mill jar, add an appropriate amount of anhydrous ethanol or deionized water as the ball milling medium, use zirconia balls as grinding balls, and ball mill and mix for 4-12 hours at a speed of 200-400 rpm to obtain a uniform slurry.

[0025] S3. Granulation and molding: The ball-milled slurry is dried at 80-120℃ to remove the solvent. The dried mixed powder is sieved and granulated with a binder solution to obtain granules with good flowability. The granules are then loaded into a mold and dry-pressed under a pressure of 10-100MPa to obtain ceramic green bodies. The green bodies can be further subjected to cold isostatic pressing at a pressure of 100-300MPa for 1-5 minutes to improve the density and uniformity of the green bodies.

[0026] S4. Debinding and Sintering: The formed green body is placed in a sintering furnace and heated to 400-600℃ at a rate of 0.5-2℃ / min under air or an inert atmosphere, and held for 1-3 h to completely remove the binder. Then, under an inert atmosphere (such as argon) or vacuum, the temperature is raised to 1800-2200℃ at a rate of 5-10℃ / min and held for 0.5-3 h for sintering. The material is then cooled to room temperature with the furnace to obtain the doped corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material.

[0027] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0028] 1. Functional integration and performance synergy are achieved: By introducing functional dopants with specific core-shell structures into the silicon carbide matrix, while retaining the inherent high strength, high hardness, excellent wear resistance and thermal stability of silicon carbide ceramics, the material is also endowed with the ability to actively resist corrosion and catalytically degrade dioxins, thus solving the problem of the single function of traditional silicon carbide ceramics.

[0029] 2. Long-lasting and stable corrosion resistance and catalytic function: The functional dopant adopts a core-shell structure design with an anatase TiO2 core and a Ce / Sn mixed-valence silicate shell. This structure protects the photocatalytic active center of the TiO2 core through the physical barrier and chemical stability of the shell, avoiding its deactivation during high-temperature sintering and use. Meanwhile, the Ce in the shell... 3+ / Ce 4+ and Sn 2+ / Sn 4+ The mixed valence states constitute a highly efficient redox pair, which can continuously catalyze the degradation of stubborn organic pollutants such as dioxins under high temperature or light conditions, and improve the material's corrosion resistance in complex chemical environments, thus achieving long-term functional effectiveness.

[0030] 3. Optimized material structure and sintering process: Using multi-graded silicon carbide powder as the matrix is ​​beneficial for improving green density and sintering activity, resulting in a denser microstructure. Combined with an Al2O3-rare earth oxide composite sintering aid system, a liquid phase promoting densification can be formed at a relatively low sintering temperature, which is conducive to uniform grain growth and performance improvement. The introduction of short-cut carbon fibers or graphene toughening agents can effectively improve the fracture toughness of the material through crack deflection, bridging, and other mechanisms, preventing brittle fracture. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the process flow for a doped, corrosion-resistant, dioxin-resistant, and wear-resistant silicon carbide ceramic material provided in an embodiment of the present invention. Detailed Implementation

[0033] The technical solutions of the present invention will now be described with reference to the accompanying drawings. It should be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some well-known technologies. Furthermore, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0034] Example 1: A doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material, comprising the following components by weight:

[0035] 90g silicon carbide powder, 5g functional dopant, 5g sintering aid, 3g toughening agent, 1.5g dispersant, and 5g binder;

[0036] The preparation method of the functional dopant is as follows:

[0037] (1) Take 5g of anatase phase TiO2 nanopowder (particle size 30nm) and disperse it in 500ml of 0.1mol / L dilute nitric acid solution. Sonicate for 1h, collect by centrifugation, wash twice with deionized water and ethanol, and redisperse the washed TiO2 nanopowder in 250ml of anhydrous ethanol to prepare an ethanol dispersion of 20mg / mL.

[0038] (2) Dissolve cerium ammonium nitrate (Ce:Si molar ratio = 1:20, calculated amount) in a 4:1 mixture of ethanol:water to prepare a 5wt% metal salt solution. Dissolve tetraethyl orthosilicate (TEOS, TiO2:TEOS mass ratio = 1:0.3, calculated amount) in anhydrous ethanol to prepare a 15wt% silicate ester solution. Adjust the pH to 3 with concentrated hydrochloric acid.

[0039] (3) The metal salt solution was slowly added dropwise to the acid-catalyzed silicate solution, and TiO2 nanopowder dispersion was added after mixing evenly. Under nitrogen protection, the temperature was raised to 60°C and the rotation speed was 500 rpm. 10 mL of deionized water: anhydrous ethanol = 1:1 mixture was slowly added dropwise (1 drop / second) for 1.5 h. The temperature was kept constant at 60°C and the reaction was stirred for 18 h.

[0040] (4) Cool to room temperature, centrifuge at 10,000 rpm for 8 min to collect the solid, wash with anhydrous ethanol and deionized water alternately by centrifugation 4 times each, and dry under vacuum at 80℃ for 12 h to obtain primary powder;

[0041] (5) In a tube furnace, the temperature is increased to 350°C at 2°C / min under an oxygen atmosphere and held for 2 hours. Then, the temperature is increased to 800°C at 5°C / min under a nitrogen atmosphere and held for 3 hours. The furnace is then cooled to obtain functional dopant powder.

[0042] The preparation method of the doped corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material is as follows:

[0043] S1, Preparation of functional dopants;

[0044] Raw material mixing: Weigh each component according to weight, including 90g of silicon carbide powder (0.1-1μm 22.5g). , , 5g of functional dopant, 5g of sintering aid (3.75g of Al2O3, 1.25g of Y2O3), 3g of toughening agent (short-cut carbon fiber, 50-100μm in length), and 1.5g of dispersant (polyacrylic acid) were weighed and placed into a 500ml zirconia ball mill jar. 200ml of anhydrous ethanol was added as the ball milling medium, and zirconia grinding balls (ball-to-material ratio 3:1) were added. The ball mill was run at 400rpm for 8 hours to obtain a uniform slurry.

[0045] S3. Granulation and Molding: Pour the slurry into an evaporating dish and dry it in a 100℃ oven for 12 hours. Pass the dried powder through a 100-mesh sieve. Add 5g of binder (polyvinyl alcohol, prepared as a 10wt% aqueous solution), granulate, and pass through a 40-mesh sieve to obtain free-flowing granules. Coat the mold with a release agent, fill it with the granules, and dry press: 50MPa pressure, hold for 30s; then cold isostatic pressing: 200MPa pressure, hold for 3min, to obtain the desired size. raw blank;

[0046] S4. Debinding and Sintering: The green blank is placed in an alumina crucible and then placed in a sintering furnace. Under an air atmosphere, the temperature is increased to 500°C at 1°C / min and held for 2 hours to remove the binder. Then, the atmosphere is switched to argon, and the temperature is increased to 1950°C at 8°C / min and held for 1.5 hours for sintering. The blank is then cooled to room temperature in the furnace (cooling rate of about 10°C / min) to obtain the doped corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material.

[0047] Example 2: A doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material, comprising the following components by weight:

[0048] 85g silicon carbide powder, 8g functional dopant, 4g sintering aid, 2g toughening agent, 2g dispersant, and 8g binder;

[0049] The preparation method of the functional dopant is as follows:

[0050] (1) Take 8g of anatase TiO2 nanoparticles (particle size 30nm) and disperse them in 800ml of 0.1mol / L dilute nitric acid solution. Sonicate for 1h, collect by centrifugation, wash twice with deionized water and ethanol, and redisperse the washed TiO2 nanoparticles in 400ml of anhydrous ethanol to prepare an ethanol dispersion of 20mg / mL.

[0051] (2) Dissolve stannous chloride (Sn:Si molar ratio = 1:15, calculated amount) in a 4:1 mixture of ethanol:water to prepare a 6wt% metal salt solution. Dissolve tetraethyl orthosilicate (TEOS, calculated amount according to TiO2:TEOS mass ratio = 1:0.4) in anhydrous ethanol to prepare an 18wt% silicate ester solution. Adjust the pH to 3.5 with concentrated hydrochloric acid.

[0052] (3) The metal salt solution was slowly added dropwise to the acid-catalyzed silicate solution, and the mixture was evenly mixed. TiO2 nanopowder dispersion was added, and the temperature was raised to 65°C under nitrogen protection. The rotation speed was 550 rpm, and 15 mL of deionized water: anhydrous ethanol = 1:1 mixture (1.5 drops / second) was slowly added dropwise for 1.8 h. The temperature was kept constant at 65°C, and the reaction was stirred for 20 h.

[0053] (4) Cool to room temperature, centrifuge at 10,000 rpm for 10 min to collect the solid, wash with anhydrous ethanol and deionized water alternately by centrifugation 5 times each, and vacuum dry at 80℃ for 12 h to obtain primary powder;

[0054] (5) In a tube furnace, the temperature is increased to 350°C at 2°C / min under an oxygen atmosphere and held for 2 hours. Then, the temperature is increased to 850°C at 5°C / min under a nitrogen atmosphere and held for 2.5 hours. The furnace is then cooled to obtain functional dopant powder.

[0055] The preparation method of the doped corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material is as follows:

[0056] S1, Preparation of functional dopants;

[0057] Raw material mixing: Weigh each component according to weight, including 85g of silicon carbide powder (0.1-1μm2 1.25g). , , ), functional dopant 8g, sintering aid 4g (Al2O3 2.4g, Y2O3 1.6g), toughening agent 2g (graphene nanosheets, 3-5 layers, specific surface area 300-500m²), 2 / g), dispersant (sodium polycarboxylate) 2g, put the weighed silicon carbide powder, functional dopant, sintering aid, toughening agent and dispersant into a 500ml zirconia ball mill jar, add 200ml anhydrous ethanol as the ball milling medium, add zirconia grinding balls (ball-to-material ratio 3:1), run the ball mill at 350rpm for 10h to obtain a uniform slurry;

[0058] S3. Granulation and Molding: Pour the slurry into an evaporating dish and dry it in an oven at 110℃ for 10 hours. Pass the dried powder through a 100-mesh sieve. Add 8g of binder (carboxymethyl cellulose, prepared as an 8wt% aqueous solution), granulate, and pass through a 40-mesh sieve to obtain free-flowing granules. Coat the mold with a release agent, fill it with the granules, and dry press: 60MPa pressure, hold for 30s; then cold isostatic pressing: 250MPa pressure, hold for 2min, to obtain the desired size. raw blank;

[0059] S4. Debinding and Sintering: The green blank is placed in an alumina crucible and then placed in a sintering furnace. Under an air atmosphere, the temperature is increased to 450°C at 1°C / min and held for 2.5 hours to remove the binder. Then, the temperature is switched to an argon atmosphere and increased to 2000°C at 8°C / min. The temperature is held for 2 hours for sintering. The blank is then cooled to room temperature in the furnace (cooling rate of about 10°C / min) to obtain the doped corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material.

[0060] Example 3: A doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material, comprising the following components by weight:

[0061] 92g silicon carbide powder, 3g functional dopant, 6g sintering aid, 4g toughening agent, 1g dispersant, and 3g binder;

[0062] The preparation method of the functional dopant is as follows:

[0063] (1) Take 3g of anatase phase TiO2 nanoparticles (particle size 30nm) and disperse them in 300ml of 0.1mol / L dilute nitric acid solution. Sonicate for 1h, collect by centrifugation, wash twice with deionized water and ethanol, and redisperse the washed TiO2 nanoparticles in 150ml of anhydrous ethanol to prepare an ethanol dispersion of 20mg / mL.

[0064] (2) Mix cerium ammonium nitrate and tin tetrachloride in a Ce:Sn molar ratio of 1:1, dissolve in an ethanol:water mixture of 4:1, and prepare a 4wt% metal salt solution (calculate the amount based on the total Ce:Sn:Si molar ratio of 1:1:30). Dissolve tetraethyl orthosilicate (TEOS, calculated based on the TiO2:TEOS mass ratio of 1:0.2) in anhydrous ethanol to prepare a 12wt% silicate ester solution, and adjust the pH to 2.5 with concentrated hydrochloric acid.

[0065] (3) The metal salt solution was slowly added dropwise to the acid-catalyzed silicate solution, and TiO2 nanopowder dispersion was added after mixing evenly. Under nitrogen protection, the temperature was raised to 55°C and the rotation speed was 450 rpm. 8 mL of deionized water: anhydrous ethanol = 1:1 mixture was slowly added dropwise (1 drop / second) for 1.2 h. The temperature was kept constant at 55°C and the reaction was stirred for 15 h.

[0066] (4) Cool to room temperature, centrifuge at 10,000 rpm for 6 min to collect the solid, wash with anhydrous ethanol and deionized water alternately by centrifugation 5 times each, and vacuum dry at 80℃ for 12 h to obtain primary powder;

[0067] (5) In a tube furnace, the temperature is increased to 340°C at 1.5°C / min under an oxygen atmosphere and held for 3 hours. Then, the temperature is increased to 750°C at 4°C / min under a nitrogen atmosphere and held for 4 hours. The furnace is then cooled to obtain functional dopant powder.

[0068] The preparation method of the doped corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material is as follows:

[0069] S1, Preparation of functional dopants;

[0070] Raw material mixing: Weigh each component according to weight, including 92g of silicon carbide powder (0.1-1μm 27.6g). , , ), 3g of functional dopant, 6g of sintering aid (4.2g of Al2O3, 1.8g of Y2O3), 4g of toughening agent (short-cut carbon fiber, 30-80μm in length), and 1g of dispersant (tetramethylammonium hydroxide). The weighed silicon carbide powder, functional dopant, sintering aid, toughening agent, and dispersant were placed in a 500ml zirconia ball mill jar, 200ml of anhydrous ethanol was added as the ball milling medium, and zirconia grinding balls (ball-to-material ratio 3:1) were added. The ball mill was run at 200rpm for 12 hours to obtain a uniform slurry;

[0071] S3. Granulation and Molding: Pour the slurry into an evaporating dish and dry in an oven at 80℃ for 15 hours. Pass the dried powder through a 120-mesh sieve. Add 3g of binder (hydroxypropyl methylcellulose, prepared as a 12wt% aqueous solution), granulate, and pass through a 50-mesh sieve to obtain free-flowing granules. Coat the mold with a release agent, fill with the granules, and dry press: 30MPa pressure, hold for 60s; then cold isostatic pressing: 150MPa pressure, hold for 5 minutes, to obtain the desired size. raw blank;

[0072] S4. Debinding and Sintering: The green blank is placed in an alumina crucible and then placed in a sintering furnace. Under an air atmosphere, the temperature is increased to 400°C at 0.8°C / min and held for 3 hours to remove the binder. Then, the temperature is switched to an argon atmosphere and increased to 1850°C at 6°C / min. The temperature is held for 3 hours for sintering. The blank is then cooled to room temperature with the furnace (cooling rate of about 8°C / min) to obtain the doped corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material.

[0073] Comparative Example 1: Based on Example 1, the difference is that silicon carbide uses a single particle size. The rest is the same as in Example 1.

[0074] Comparative Example 2: Based on Example 1, the difference is that there is no functional dopant, and the rest is the same as Example 1.

[0075] Comparative Example 3: Based on Example 1, the difference is that: TiO2 catalyst is supported on the surface. First, the conventional silicon carbide ceramic of Example 1 is prepared. The ceramic sheet is immersed in TiO2 sol (anatase phase, concentration 5wt%), coated by pull coating at a pull speed of 2mm / s, repeated 3 times, and kept at 450℃ for 1h to crystallize the TiO2 coating to obtain the surface-supported ceramic. The rest is the same as in Example 1.

[0076] Comparative Example 4: Based on Example 1, the difference is that the catalytic components are directly mixed, anatase TiO2 nanopowder is directly added without coating, all components are ball-milled and mixed at one time, and the rest is the same as in Example 1.

[0077] Comparative Example 5: Based on Example 1, the difference is that a single-valence functional dopant is used, using only Ce.4+ (Cerium nitrate), without introducing Sn, without reduction treatment, under air atmosphere throughout, held at 600℃ for 3 hours, to obtain Ce. 4+ TiO2 was coated with a single-valence silicate, and the rest was the same as in Example 1.

[0078] Comparative Example 6: Based on Example 1, the difference is that no toughening agent is used, and the rest is the same as Example 1.

[0079] Performance testing:

[0080] 1. Density Test: The silicon carbide ceramic samples prepared in Examples 1-3 and Comparative Examples 1-6 were tested according to GB / T 25995-2010 "Test Methods for Density and Apparent Porosity of Fine Ceramics". The Archimedes displacement method was used. The dried samples were dried to constant weight in an oven at 100±5℃, and the mass m1 was obtained. The samples were boiled in distilled water to remove open-pore gases, and the buoyant weight m2 was obtained. The samples were then removed, surface moisture was wiped off, and the mass m3 of the saturated sample in air was obtained. Bulk density calculation formula: The experimental results are shown in Table 1.

[0081] 2. Bending Strength Test: The silicon carbide ceramic samples prepared in Examples 1-3 and Comparative Examples 1-6 were tested using the three-point or four-point bending method according to GB / T6569-2006 "Test Method for Bending Strength of Fine Ceramics". Rectangular cross-section beam specimens (typical dimensions: length × width × thickness = 36mm × 4mm × 3mm) were prepared and loaded at a constant rate on a universal testing machine until fracture. The three-point bending formula is as follows: Four-point bending formula: Where F is the fracture load, L is the span, l is the inner span, b and h are the sample width and thickness, and the experimental results are shown in Table 1.

[0082] 3. Fracture Toughness Test: The silicon carbide ceramic samples prepared in Examples 1-3 and Comparative Examples 1-6 were tested according to GB / T23806-2009 "Test Method for Fracture Toughness of Fine Ceramics - Single-Sided Precracked Beam (SEPB) Method". A sharp crack was pre-induced on one side of the rectangular sample using the single-sided precracked beam method. The crack was then propagated by a three-point bending load. The calculation formula is: K IC =(3FLa 1 / 2 ) / (2bw 2 ) ×Y, where F is the fracture load, L is the span, a is the crack depth, b and w are the specimen width and thickness, and Y is the geometric shape factor. The experimental results are shown in Table 1.

[0083] 4. Vickers Hardness Test: The silicon carbide ceramic samples prepared in Examples 1-3 and Comparative Examples 1-6 were tested using a Vickers hardness tester with a test force of 98.07 N (10 kgf). The diamond square pyramid indenter was pressed into the sample surface with the specified test force and held for 10-15 seconds before the test force was removed. The diagonal lengths d1 and d2 of the indentation were measured. The hardness value was calculated using the formula: HV = 0.1891F / d 2 Where F is the test force (N) and d is the arithmetic mean of the two diagonals (mm), the experimental results are shown in Table 1;

[0084] 5. Wear Rate Test: The silicon carbide ceramic samples prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to sliding friction under dry, unlubricated conditions using a ball-and-disc rotating sliding method, according to JC / T2408-2017 "Test Methods for Friction and Wear of Fine Ceramics". The ceramic sample was used as the disc, and the grinding balls (usually Al2O3 or SiC balls) were used as the balls. The wear rate was calculated using the formula: W = V / (F N ×L), where V is the wear volume (mm). 3 ), determined by surface profilometer or mass loss method; F N denoted as normal load (N); L represents the total sliding distance (m). The experimental results are shown in Table 1.

[0085] 6. Acid Resistance Mass Loss Rate Test: The silicon carbide ceramic samples prepared in Examples 1-3 and Comparative Examples 1-6 were immersed in a sulfuric acid solution of a specified concentration (e.g., 1 mol / L H₂SO₄) according to JC / T 2138-2012 "Test Method for Acid and Alkali Corrosion Resistance of Fine Ceramics" and kept in a constant temperature bath at 80±1℃ for 720 h. The samples were then removed, cleaned, dried, and weighed. The mass loss rate was calculated using the following formula: Where m0 and m1 are the masses before and after corrosion, respectively, and the experimental results are shown in Table 1.

[0086] 7. Alkali Resistance Mass Loss Rate Test: The silicon carbide ceramic samples prepared in Examples 1-3 and Comparative Examples 1-6 were immersed in a sodium hydroxide solution of a specified concentration (e.g., 1 mol / L NaOH) according to JC / T 2138-2012 "Test Method for Acid and Alkali Corrosion Resistance of Fine Ceramics" for 720 hours. The samples were then removed, cleaned, dried, and weighed. The mass loss rate was calculated using the following formula: Where m0 and m1 are the masses before and after corrosion, respectively, and the experimental results are shown in Table 1.

[0087] 8. Dioxin Degradation Efficiency Test: The silicon carbide ceramic samples prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to dioxin standard irradiation (HJ 77.3-2008) "Determination of Dioxins in Solid Waste by Isotope Dilution High-Resolution Gas Chromatography-High-Resolution Mass Spectrometry" in a reactor containing a dioxin standard solution. The samples were reacted for 24 hours under ultraviolet light irradiation (wavelength 254-365 nm). The dioxin concentration before and after the reaction was measured using high-resolution gas chromatography-high-resolution mass spectrometry. The degradation efficiency was calculated using the following formula: C0, C t The initial and post-reaction concentrations are shown in Table 1.

[0088] Table 1. Test data of various properties of silicon carbide ceramics

[0089]

[0090] Data Analysis:

[0091] 1. Mechanical Property Analysis: Examples 1 (Ce-doped + carbon fiber) and 3 (Ce / Sn co-doped + carbon fiber) exhibit flexural strengths in the range of 450-500 MPa and significantly improved fracture toughness due to the combination of gradation optimization and fiber toughening. Example 2 (Sn-doped + graphene) demonstrates outstanding fracture toughness thanks to the unique toughening mechanism of graphene. Comparative Example 1 (single particle size) suffers from low particle packing efficiency, resulting in a significant decrease in density and strength; its flexural strength reaches only 320 MPa, significantly lower than the examples. Comparative Examples 4 (direct mixing of catalytic components) and 3 (surface-loaded TiO2) show that direct mixing or post-loading of catalytic components disrupts matrix continuity or introduces interfacial weaknesses, leading to lower mechanical properties (especially strength and toughness) compared to the examples. Comparative Example 6 (no toughening agent) achieves higher matrix hardness and density, but the material is brittle and exhibits low fracture toughness (below 4.0 MPa·m). 1 / 2 It has poor impact and thermal shock resistance.

[0092] 2. Wear and Corrosion Resistance Analysis: The examples, through high-density sintering, minimize porosity and block the penetration channels of corrosive media. The introduction of toughening phases (carbon fiber, graphene) improves toughness without significantly sacrificing hardness. This allows the examples to resist indentation and inhibit crack propagation during abrasive wear, thus exhibiting excellent wear resistance. Regarding corrosion resistance, the high-density matrix combined with stable CeO2 or SnO2 doped phases remains stable in acidic and alkaline environments. The silicon carbide prepared in the examples, after immersion in concentrated sulfuric acid and sodium hydroxide for 720 hours, showed a mass loss of less than 0.2%. Comparative Example 1 (single particle size) and Comparative Example 4 (straight particle size) showed similar results. (With mixed components), due to lower density or uneven structure, there are more open pores, making it easier for corrosive media to penetrate, resulting in decreased corrosion resistance. Wear resistance is also affected by lower strength. In Comparative Example 3 (surface-loaded TiO2), the surface coating peels off under harsh wear or corrosion environments, leading to protection failure. In Comparative Example 6 (without toughening agent), although the hardness may be very high, it is brittle and is prone to cracking and propagation under impact wear or thermal shock conditions, resulting in a shortened wear life. Comparative Example 2 (undoped) and Comparative Example 5 (single valence state) have corrosion resistance that depends on the matrix silicon carbide and generally perform well, but lack the additional protection or stabilizing effect of dopants for specific corrosive environments.

[0093] 3. Dioxin degradation efficiency analysis: Ce element (especially Ce) 3+ / Ce 4+ Mixed valence states are known highly efficient catalytic active sites that can activate C-Cl bonds. Sn doping can also provide additional active sites. In Examples 1 and 3, Ce was reduced to contain Ce. 3+ / Ce 4+ Mixed valence state, Sn in Example 2 with Sn 2+ / Sn 4+ The form exists; Example 3 is Ce / Sn co-doped. These mixed or co-doped valence states can effectively promote the separation of photogenerated electrons and holes, greatly improving the photocatalytic efficiency, so that the dioxin degradation efficiency can reach 90-95%. Comparative Example 2 (no functional dopant), the pure silicon carbide matrix has almost no catalytic activity, and the dioxin degradation efficiency is close to zero. Comparative Example 5 (single valence state Ce) 4+ ), Ce 4+ The catalytic activity is typically lower than that of mixed valence states (Ce). 3+ / Ce 4 +The degradation efficiency of Comparative Example 1 (mixed valence Ce) is lower than that of Comparative Example 4 (directly mixed catalytic components). The active components are unevenly dispersed, easily agglomerated and deactivated, and will fall off during use due to weak bonding, resulting in low and unstable catalytic efficiency. Although Comparative Example 3 (surface-loaded TiO2) has certain photocatalytic or catalytic potential, the loading amount is limited, and the problem of bonding with the matrix will affect its long-term activity and stability. Comparative Examples 1 and 6 have the same catalytic components as Comparative Example 1, but their poor mechanical properties (Comparative Example 1) or brittleness (Comparative Example 6) will cause the materials to be easily damaged in practical use, thereby causing the catalytic function to fail prematurely.

[0094] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material, characterized in that, By weight, it includes the following components: silicon carbide powder: 80-95 parts, functional dopant: 1-10 parts, sintering aid: 2-8 parts, toughening agent: 2-5 parts, dispersant: 0.5-3 parts, binder: 0.5-10 parts; The functional dopant is a core-shell structured nanocomposite powder with an anatase TiO2 core and a crystalline silicate shell containing mixed valence states Ce / Sn. The preparation method is as follows: (1) After being ultrasonicated and washed with dilute nitric acid, anatase TiO2 nanopowder was dispersed in anhydrous ethanol to obtain a TiO2 dispersion; (2) Dissolve the metal salt in a mixture of ethanol and water to obtain a metal salt solution; dissolve tetraethyl orthosilicate in anhydrous ethanol, and then adjust the pH to 2-4 with acid to obtain an acid-catalyzed silicate ester solution; (3) The metal salt solution is mixed with the acid-catalyzed silicate solution, and then the TiO2 dispersion is added. Under nitrogen protection and heating and stirring conditions, a water-ethanol mixture is slowly added dropwise to carry out hydrolysis-condensation reaction to form an amorphous coating layer. (4) After the reaction is complete, the solid product is collected by centrifugation, washed and dried to obtain primary powder; (5) The primary powder is first heat-treated at 340-360°C in an oxygen atmosphere, and then heat-treated at 600-900°C in a nitrogen atmosphere, and then cooled in the furnace to obtain the functional dopant.

2. The doped, corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material according to claim 1, characterized in that, In the preparation process (1) of the functional dopant, the particle size of the anatase phase TiO2 nanopowder is 20-50nm, and the ratio of the anatase phase TiO2 nanopowder to concentrated nitric acid is 1g:100ml.

3. The doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material according to claim 1, characterized in that, In the preparation process (2) of the functional dopant, the metal salt is at least one of cerium ammonium nitrate, cerium nitrate, stannous chloride, and stannous tetrachloride.

4. The doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material according to claim 1, characterized in that, In the preparation process (3) of the functional dopant, the mass ratio of TiO2 to tetraethyl orthosilicate is 1:0.1-0.5, and the molar ratio of metal ions in the metal salt to silicon in tetraethyl orthosilicate is 1:5-100.

5. The doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material according to claim 1, characterized in that, The silicon carbide powder is composed of four different silicon carbide micro powders with particle sizes of 0.1-10μm mixed in a specific ratio, wherein the 0.1-1μm micro powder accounts for 20-30%, the 1-5μm micro powder accounts for 20-30%, the 5-20μm micro powder accounts for 25-27%, and the 20-50μm micro powder accounts for 20-25%.

6. The doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material according to claim 1, characterized in that, The sintering aid is a composite of Al2O3 and rare earth oxides, wherein the rare earth oxides are at least one of Y2O3, Sc2O3, and Yb2O3, and the molar ratio of Al2O3 to rare earth oxides is 2.5-3.5:1.5-2.

5.

7. The doped, corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material according to claim 1, characterized in that, The toughening agent is short-cut carbon fiber or graphene nanosheets.

8. The doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material according to claim 1, characterized in that, The dispersant is at least one of polyacrylic acid, sodium polycarboxylate, sodium humate, tetramethylammonium hydroxide, or polyethylene glycol.

9. The doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material according to claim 1, characterized in that, The adhesive is at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl methyl cellulose, or polyvinylpyrrolidone.

10. A method for preparing a doped, corrosion-resistant, dioxin-resistant, wear-resistant silicon carbide ceramic material as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Preparation of functional dopants; S2. Raw material mixing: Weigh each component according to the weight parts, and ball mill the silicon carbide powder, functional dopant, sintering aid, toughening agent and dispersant for 4-12 hours at a speed of 200-400 rpm to obtain a uniform slurry. S3. Granulation and molding: The ball-milled slurry is dried at 80-120℃, sieved, and granulated with a binder. It is then dry-pressed under a pressure of 10-100MPa to obtain a ceramic green body. The green body can be further subjected to cold isostatic pressing at a pressure of 100-300MPa for 1-5 minutes to improve the density and uniformity of the green body. S4. Debinding and Sintering: The green body is first heated to 400-600℃ at 0.5-2℃ / min and held for 1-3 hours to remove the binder. Then, it is sintered in an inert atmosphere or vacuum at 5-10℃ / min to 1800-2200℃ and held for 0.5-3 hours. After cooling to room temperature in the furnace, the doped corrosion-resistant, dioxin-resistant silicon carbide wear-resistant ceramic material is obtained.

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