A single-atom titanium in-situ surface reinforced refractory ceramic material and a preparation method and applications thereof

Abstract

The application provides a single-atom titanium in-situ surface reinforced refractory ceramic material and a preparation method and application thereof, and the refractory ceramic material comprises the following raw materials in percentage by mass: 55-75% of solid waste purification material, 15-25% of refractory aggregate, 0.5-3% of single-atom titanium dopant, 4-8% of binder, and 3-7% of regulator; the refractory ceramic material has an in-situ autogenous glaze layer: permanent protection under high-temperature working conditions of aluminum furnace, and completely solves the failure problem of traditional glaze layers; the glaze layer has a leap-forward improvement in erosion resistance and penetration resistance, and greatly prolongs the service life of the material. The preparation method realizes high-proportion resource utilization of industrial solid waste, has extremely strong application construction adaptability, is free of glazing, is easy to maintain, and reduces the on-site application cost.

Description

Technical Field

[0001] This invention belongs to the field of advanced inorganic non-metallic materials technology, specifically relating to a single-atom titanium in-situ surface-strengthened refractory ceramic material, its preparation method, and its application. Background Technology

[0002] Currently, refractory ceramic materials used in aluminum alloy smelting furnaces, holding furnaces, and scrap aluminum recycling furnaces are mainly high-alumina and mullite castables, relying on the matrix's inherent resistance to molten aluminum erosion and thermal shock for service. Some solutions attempt to improve the protective effect by applying an external glaze or surface coating, but the following technical problems still exist: (1) Conventional glazes cannot exist stably under aluminum furnace conditions. Traditional glazes have a low softening temperature, making them prone to softening, flowing, and contaminating the molten aluminum under the high temperature of the aluminum furnace and the scouring of the molten aluminum. Furthermore, they do not match the thermal expansion of the substrate, causing them to crack and peel off after thermal shock, thus losing their protective properties.

[0003] (2) Adverse reactions occur between the glaze components and the molten aluminum and the substrate. Conventional glazes contain alkali metals and alkaline earth metals, which are prone to reduction reactions with molten aluminum, causing the molten aluminum to increase in iron and silicon, and deteriorate, affecting the quality of aluminum alloys; at the same time, they react with the refractory matrix to form low-melting-point phases, which exacerbate the risks of corrosion, penetration and furnace penetration.

[0004] (3) The surface of the refractory ceramic material is not densely protected, and the aluminum melt penetrates severely. Traditional refractory ceramic materials have a porous structure, which allows molten aluminum to easily penetrate through the pores, causing the bricks to crack, peel off, have a short lifespan, require frequent replacement, and have high energy consumption and costs.

[0005] (4) High consumption of natural minerals and low level of greening The raw materials rely on natural high-alumina materials, resulting in high energy consumption in production; a large amount of waste refractory ceramic materials and secondary aluminum ash cannot be utilized at high value, leading to the accumulation of solid waste, which does not meet the requirements of green and low-carbon development.

[0006] (5) On-site construction is limited, and secondary glazing is not possible. Aluminum furnaces are mostly cast on-site as a whole or constructed from precast blocks, making it impossible to complete glazing and high-temperature firing, and thus difficult to maintain.

[0007] Therefore, there is an urgent need to develop a new refractory ceramic material technology that can solve the problems of traditional glazes being prone to flowing, contaminating molten aluminum, peeling off, having a short lifespan, and being costly under aluminum furnace operating conditions. Summary of the Invention

[0008] To solve the above-mentioned technical problems, the present invention provides a refractory ceramic material with in-situ surface strengthening of single-atom titanium, comprising the following raw materials by mass percentage: 55-75% purified solid waste material, 15-25% refractory aggregate, 0.5-3% single-atom titanium dopant, 4-8% binder, and 3-7% regulator; the purified solid waste material includes recycled waste refractory ceramic material and recycled secondary alumina ash material; the refractory aggregate is selected from high-alumina aggregate or mullite aggregate; the single-atom titanium dopant is titanium oxide-titanium oxide. The binder is pure calcium aluminate cement with an AlO content ≥70%, which provides low-temperature strength for the material, is suitable for on-site vibration casting and machine-pressed prefabrication, and can achieve construction strength without high-temperature sintering; the regulator is an alkaline earth silicate and titanate composite agent; the regulator is free of alkali metals and harmful impurities. The regulator of this invention only adopts an alkaline earth metal silicate + alkaline earth titanate composite system, and is completely free of alkali metal ions such as Na and K, as well as harmful impurities such as free iron and active silicon.

[0009] Alkali metal ions are low-valence, large-radius ions that readily disrupt the three-dimensional covalent network framework of silicate systems (Si-Si and Si-O), resulting in a loose network structure, reduced bond energy, and the formation of a large amount of low-melting-point glassy phases. Simultaneously, alkali metal ions exhibit extremely high migration activity, readily undergoing ion diffusion and inducing redox side reactions at high temperatures. In contrast, alkaline earth metal ions possess a strong ion field and stable coordination structure, embedding themselves in the silicate lattice only as network intermediates without disrupting the integrity of the Si-O main network. This fundamentally avoids the formation of low-melting-point phases and ion migration side reactions, laying the microstructural foundation for the high-temperature stability and chemical inertness of the glaze layer. Combined with precise control of the glaze layer's softening point and density using single-atom titanium, this ensures compatibility between the glaze layer and molten aluminum, preventing reduction reactions and avoiding iron and silicon enrichment, thus guaranteeing the purity of the aluminum alloy.

[0010] Furthermore, the molar ratio of the alkaline earth silicate to the titanate is 1:2 to 2:1.

[0011] Furthermore, the silicate is selected from one of dicalcium silicate (2CaOSiO2), tricalcium silicate (3CaOSiO2), calcium metasilicate (CaSiO3), magnesium metasilicate (MgSiO3), magnesium orthosilicate (Mg2SiO4), strontium metasilicate (SrSiO3), barium metasilicate (BaSiO3), and calcium-magnesium composite silicate (CaOMgOSiO2).

[0012] Furthermore, the alkaline earth titanate is selected from one of calcium titanate (CaTiO3), magnesium titanate (MgTiO3), strontium titanate (SrTiO3), barium titanate (BaTiO3), calcium-titanium composite titanate (CaOTiO2MgO), and magnesium-titanium composite titanate (MgOTiO2SiO2).

[0013] Furthermore, the proportions of recycled waste refractory ceramic materials and recycled secondary alumina ash in the refractory ceramic materials are 30-45% and 20-30%, respectively. The recycled waste refractory ceramic materials are obtained by crushing, removing iron, screening, and calcining and activating waste high-alumina or mullite refractory bricks at 1000-1100℃. The waste refractory ceramic materials form the main framework of the material, reducing the consumption of natural minerals and improving the basic refractory performance. The recycled secondary alumina ash is obtained by denitrifying, desalting, removing impurities, and calcining and activating secondary alumina ash from the aluminum industry at 800-900℃. The recycled secondary alumina ash supplements the aluminate phase, synergistically promoting in-situ glazing with single-atom titanium, achieving closed-loop utilization of solid waste from the aluminum industry. The active aluminate phase precipitated from the recycled secondary alumina ash dissociates into free Al at high temperatures. 3+ Ca 2+ Mg 2+ The aluminate ions are dispersed on the surface and grain boundaries of the material. Single-atom titanium acts as a nucleation site, which greatly reduces the nucleation barrier of the glaze phase. This allows aluminate ions to preferentially adsorb, aggregate, and arrange themselves in an orderly manner on the surface of single-atom titanium, achieving low-temperature and rapid nucleation. In-situ glazing can be initiated without excessively high temperatures, solving the problem of difficult glazing of pure aluminates.

[0014] Furthermore, the refractory aggregate has a particle size of 0.5-5mm; the refractory aggregate improves the high-temperature strength, thermal shock resistance and structural stability of refractory ceramic materials, and is suitable for the high-temperature service requirements of aluminum furnaces.

[0015] Furthermore, the single-atom titanium dopant is synthesized in a solid state at 1300-1400℃ using titanium oxide and aluminum oxide as raw materials.

[0016] Furthermore, the solid-phase synthesized product is ground to a particle size ≤100nm and then dispersed at the atomic level to obtain a titanium oxide-alumina intermetallic compound oxide, namely a single-atom titanium dopant. The single-atom titanium dopant catalyzes the in-situ glazing of surface components at high temperature; it also regulates the ceramic crystal phase structure, enhances the glaze-matrix bonding force, and lowers the glazing temperature to ensure that the glaze layer does not flow or contaminate the aluminum melt.

[0017] Single-atom titanium serves as a high-energy nucleation site, preferentially adsorbing free silica-oxygen groups, alumino-oxygen groups, and alkaline earth metal ions from the matrix surface. This induces the ions to arrange themselves in an orderly and oriented manner along the surface of single-atom titanium, resulting in stacking and crystallization. Gradually, Ti-O-Si, Ti-O-Al, and Ti-OM (M=Ca / Mg) cross-linked covalent networks are constructed, spontaneously transforming scattered particulate components into a dense glaze layer.

[0018] 1. Microscopic mechanisms for lowering glaze formation temperature The interfacial polarization effect of single-atom titanium significantly reduces the energy barrier for ion migration, grain boundary diffusion, and network aggregation; without the ultra-high temperature required for glazing of traditional refractory materials, component diffusion, network cross-linking, and crystallization glazing can be completed in the medium temperature range of around 1250℃, achieving low-temperature rapid in-situ glazing.

[0019] 2. Microscopic mechanisms that prevent the glaze from flowing at high temperatures Single-atom titanium participates in the construction of the Ti-Si-Al-O covalent network, which significantly improves the polymerization degree, high-temperature viscosity and glass softening point of the glaze glass phase; at the same time, it induces the precipitation of high-melting-point titanate and aluminate crystal phases, and inhibits the slippage, spreading and flow of the glass phase at high temperature; the overall softening point of the glaze is much higher than the working temperature of the aluminum furnace, and it always maintains a solid and dense structure at high temperature, without deformation or flow.

[0020] After the components of the refractory ceramic material are uniformly mixed, the single-atom titanium is highly dispersed in the gap between the solid waste matrix and the refractory aggregate; pure calcium aluminate cement encapsulates the aggregate and solid waste particles to form a medium- and low-temperature bonded phase; during high-temperature service, the surface components generate a dense self-generated glaze layer under the catalysis of single-atom titanium, the interior maintains a porous thermal shock resistant structure, and a dense protective layer is formed on the surface. The components transition continuously from the surface to the interior, without the risk of interface cracking or peeling.

[0021] This invention also provides a method for preparing a single-atom titanium in-situ surface-strengthened refractory ceramic material as described above, comprising the following steps: Step S1: Preparation of purified solid waste material; Step S2: Preparation of single-atom titanium dopant; Step S3: Ingredient preparation and mixing; Weigh out the solid waste purification material, refractory aggregate, single-atom titanium dopant, binder, and regulator according to the formula, and put them into a high-strength mixer for dry mixing for 10-15 minutes; add 4-10% recycled clean water and wet mix for 8-12 minutes to make a mixture that can be vibrated for casting and machine-pressed; industrial recycled purified water is used, which is environmentally friendly and water-saving; function: to realize the mixing and plasticization of raw materials and meet the requirements of casting / machine-pressed molding process.

[0022] Step S4: The mixture is formed into a preform; Step S5: The shaped green body is left to cure at room temperature and demolded to obtain a shaped green body; the shaped green body is sent into a kiln for firing, and after cooling, a refractory ceramic material with in-situ surface strengthening of single-atom titanium is obtained.

[0023] Furthermore, the preparation of the recycled waste refractory ceramic material in step S1 solid waste purification is as follows: S11: Waste refractory bricks are coarsely crushed to a particle size ≤20mm; S12: Iron removal (magnetic separation to remove iron impurities); S13: Select raw materials with a particle size of 0.5-5mm by fine screening and calcine them at 1000-1100℃ for 2 hours; S14: After cooling, recycled waste refractory ceramic materials are obtained; The preparation of secondary aluminum ash recycled material from solid waste purification is as follows: Step 1: Grind the secondary aluminum ash balls to a particle size ≤200 mesh; Step 2: Denitrification (calcination at 800℃ for 1 hour), water washing for desalination, filtration to remove impurities, followed by calcination and activation at 800–900℃ for 1 hour; Step 3: After cooling, secondary aluminum ash recycled material is obtained.

[0024] Impurities must be removed and activated during the preparation of recycled waste refractory ceramic materials and recycled secondary aluminum ash to ensure stable material properties.

[0025] Furthermore, the preparation steps for the single-atom titanium dopant in step S2 are as follows: S21: Mix titanium dioxide and aluminum oxide as raw materials in a molar ratio of 1:0.6-1:1.3; S22: The mixture is kept at 1300-1400℃ for 3 hours; S23: Grind to a particle size ≤100nm; S24: Single-atom titanium dopant is prepared by single-atom-level dispersion treatment. It is ultra-finely dispersed to the single-atom level to avoid agglomeration and ensure the uniformity of glaze formation.

[0026] The specific steps of step S24 are as follows: Step S241: Preparation of alkali-free dispersion system slurry; Add 25%-35% by weight of ultrafine titanium-aluminum composite powder to high-purity deionized water, and compound with an alkali-free polymeric dispersant (one or two of citric acid and ammonium polycarboxylate). The amount of dispersant added is 1.0%-2.5% of the powder mass. Stir at room temperature for 15-20 minutes to prepare a uniform suspension slurry.

[0027] Function: By utilizing the directional adsorption of dispersant molecules on the surface of nanoparticles to form a steric hindrance layer, the primary aggregation of nanoparticles is inhibited in advance, and no alkali metals are introduced throughout the process, which meets the requirement of the present invention to be a system free of harmful impurities.

[0028] Step S242: High-energy wet nanoball milling dissociation; The suspension slurry is fed into a ball mill, and zirconia microspheres (particle size 0.3-0.5mm) are used as the grinding medium. The ball-to-material mass ratio is 3:1-5:1, the rotation speed is 1800-2200r / min, and the ball mill is circulated for 2-3 hours.

[0029] Function: Through mechanical shearing and impact, it breaks up soft agglomerates and grain boundary adhesions between powders, decomposing agglomerates into isolated nanocrystals, laying the structural foundation for subsequent dissociation to the single-atom level.

[0030] Step S243: Ultrasonic cavitation single-atom dissociation and dispersion; After ball milling, the slurry is transferred into an ultrasonic disperser. The ultrasonic power is set to 300-500W and the frequency to 20-40kHz. The mixture is then subjected to constant temperature ultrasonic treatment for 40-60 minutes. The instantaneous high pressure and micro-jet effect generated by ultrasonic cavitation further tear apart the molecular forces between particles, causing the titanium component in the titanium-aluminum composite structure to gradually dissociate into a single-atom isolated state and be uniformly suspended in the liquid phase system.

[0031] Step S244: Low-speed centrifugation to remove aggregates; The ultrasonically dispersed suspension was placed in a centrifuge and centrifuged at 3000-4000 r / min for 10-15 min to separate and remove large particle agglomerates and polycrystalline clusters that were not completely dissociated, leaving only a stable supernatant with uniformly dispersed single-atom titanium.

[0032] Step S245: Spray drying to prevent agglomeration and curing; The supernatant after classification is sent to a spray dryer with an inlet air temperature of 180-200℃ and an outlet air temperature of 80-100℃ to obtain spray-dried powder by atomization drying.

[0033] Function: Instant atomization and rapid dehydration solidify the steric hindrance effect of the dispersant, preventing secondary agglomeration of single-atom titanium during the drying process and maintaining atomic-level dispersion.

[0034] Step S246: Low-temperature lattice anchoring in an inert atmosphere; The spray-dried powder was placed in a tube furnace, and a high-purity nitrogen / argon inert atmosphere was introduced. The temperature was increased to 500-600℃ at a rate of 3-5℃ / min, and the temperature was held for 1.5-2 hours before being cooled in the furnace to obtain a single-atom titanium dopant.

[0035] Function: Single-atom titanium is anchored to the surface and inter-lattice of alumina crystal through thermal diffusion, forming a strong coordination bond-locked structure. This thermodynamically locks the single-atom dispersion configuration, preventing atomic aggregation and crystal phase agglomeration during subsequent high-temperature firing of refractory ceramics and service in aluminum furnaces.

[0036] Furthermore, based on the application scenario, two molding methods are selected. In step S4, one of the following molding methods is selected: ① Machine pressing: The mixture is added to the mold, and the pressure is maintained at 15-25MPa for 30-60s to obtain standard refractory bricks; ② Vibration casting molding: The mixture is injected into the aluminum furnace mold and vibrated to compact it, thus producing an integral cast precast part / on-site cast furnace lining; The vibration compaction process involves uniformly injecting the prepared mixture into the aluminum furnace integral casting mold or on-site furnace lining mold, and using a vibration motor with a frequency of 50-60Hz and an amplitude of 0.8-2.0mm for vibration compaction. Each layer is vibrated for 30-60s during layer-by-layer casting, and the entire casting is continuously vibrated for 90-150s until the material slurry rises, air bubbles are completely expelled, and the structure is compacted, thus obtaining the integrally cast precast part or the aluminum furnace on-site cast lining formed blank.

[0037] The standard refractory bricks or integral cast-in-place precast parts / on-site cast-in-place furnace linings produced are all pre-formed blanks.

[0038] Furthermore, the specific steps of step S5 are as follows: S51: The formed blank is left to cure at room temperature for 24-48 hours, and then demolded to obtain a shaped blank; S52: The shaped green body is fed into the kiln and heated to 1250-1400℃ at a rate of 5℃ / min. It is held at this temperature for 2-3 hours. The low-temperature firing temperature is strictly controlled at 1250–1400℃ to reduce energy consumption while ensuring the basic strength of the material. It is then naturally cooled to room temperature to obtain a refractory ceramic material with in-situ surface strengthening of single-atom titanium.

[0039] This invention also provides an application of the refractory ceramic material reinforced by in-situ single-atom titanium as described above. When the refractory ceramic material reinforced by in-situ single-atom titanium is used in aluminum alloy smelting furnaces, holding furnaces, and waste aluminum recycling furnaces, under working conditions of ≥1250℃, the surface components of the material generate a continuous and dense glaze layer in situ within 10-30 minutes under the catalysis of single-atom titanium, without the need for secondary glazing or additional firing, and automatically form a protective layer.

[0040] The refractory ceramic material with in-situ surface strengthening of single-atom titanium prepared in this application can be recycled and reused. The waste refractory ceramic material with in-situ surface strengthening of single-atom titanium can be crushed, impurities removed, screened, and directly recycled as raw material (replacing 30-40% of fresh solid waste purification material). The recycling rate is ≥90%, realizing full life cycle recycling.

[0041] This invention achieves a comprehensive breakthrough in the technical bottlenecks of existing refractory ceramic materials for aluminum alloy furnaces through four core innovative designs: in-situ glazing catalysis by single-atom titanium, resource utilization of dual industrial solid waste, one-time molding without glazing, and a pollution-free formula specifically for aluminum furnaces. It addresses seven dimensions, including protective performance, service life, green and low-carbon properties, melt protection, construction adaptability, recycling, and production energy consumption. Compared with traditional high-alumina and mullite refractory ceramic materials and external glazing coating materials, this invention possesses significant and quantifiable technical advantages, practical value, and industrial benefits.

[0042] Specifically, compared with the prior art, the beneficial effects of the present invention are as follows: 1. In-situ self-generating glaze: Provides permanent and stable protection under high-temperature conditions in aluminum furnaces, completely solving the problem of traditional glaze failure. (1) The glaze does not soften, flow, or contaminate the molten aluminum at high temperatures. The self-generated glaze produced by single-atom titanium catalysis is a high-temperature resistant ceramic glaze free of alkali metals and alkaline earth metals. Its softening point is far higher than the working temperature of aluminum furnace (≥1250℃). It does not melt, flow, or precipitate impurities under long-term scouring of aluminum liquid and corrosion of molten salt, thus eliminating the problem of traditional glazes contaminating aluminum liquid from the root.

[0043] (2) The glaze and base are integrated and do not crack or peel off under thermal shock. The self-generated glaze and the substrate have a continuous and gradual transition in composition and a high degree of matching in thermal expansion coefficient. It is a chemical bond rather than a physical adhesion. After more than 100 cycles of rapid cooling and heating, there is no cracking, peeling, or flaking. The protective life spans the entire service life of the material, solving the core defect of thermal shock failure of traditional external glaze layers.

[0044] (3) Automatic glazing, no secondary processing required The glaze layer is automatically generated in situ during the high-temperature service of the aluminum furnace, without the need for on-site glazing or secondary high-temperature firing. A continuous and dense protective layer can be formed in 10-30 minutes, achieving "one-time molding and lifelong protection".

[0045] 2. Significantly improved resistance to erosion and permeability, greatly extending the service life of the material. (1) Complete isolation between aluminum liquid and molten salt penetration The surface self-generated glaze layer has a density of ≥98%, which completely seals the internal pores of the ceramic matrix. The penetration rate of aluminum liquid and molten salt is reduced by more than 90%, eliminating the problems of brick expansion, cracking, powdering and peeling caused by penetration in traditional porous refractory ceramic materials.

[0046] (2) Resistance to aluminum melt corrosion is improved by more than 60%. Single-atom titanium optimizes the ceramic crystal phase structure, significantly enhancing the material's high-temperature corrosion resistance, reducing the static aluminum melt erosion rate by more than 60%, and improving molten salt corrosion resistance by more than 50%.

[0047] (3) Service life is extended by more than 50%, eliminating the safety risk of furnace burnout. Traditional aluminum furnace refractory ceramic materials have a lifespan of only 6-12 months, while the material of this invention has a lifespan of 12-18 months, extending the service life by more than 50%. At the same time, it avoids furnace body penetration and aluminum leakage accidents caused by erosion and seepage, greatly improving the operational safety of aluminum furnaces.

[0048] 3. High-proportion resource utilization of industrial solid waste constitutes a strategic new material for green and low-carbon development. (1) Co-utilization of solid waste significantly reduces the consumption of natural minerals. Using recycled waste refractory ceramic materials (30-45%) and recycled secondary aluminum ash (20-30%) as the core matrix, the total proportion of solid waste reaches 55-75%, which significantly replaces non-renewable minerals such as natural high-alumina materials and mullite, realizing the high-value and closed-loop utilization of aluminum industry solid waste and refractory solid waste.

[0049] (2) Production energy consumption is reduced by 30-50%, and the effect of low carbon emission reduction is significant. The process of firing at a low temperature of 1250-1400℃ is adopted. Compared with the high temperature firing of traditional refractory ceramic materials at 1500-1600℃, the production energy consumption is reduced by 30-50% and carbon emissions are reduced by more than 40%, which fully complies with the "dual carbon" policy and green manufacturing requirements.

[0050] (3) Large amount of solid waste disposal, which alleviates environmental pressure. Each ton of product can dispose of 0.55-0.75 tons of industrial solid waste such as waste refractory ceramic materials and secondary aluminum ash, effectively solving the industry pain points of solid waste accumulation and disposal difficulties in aluminum plants and refractory ceramic material plants, and has both environmental and social benefits.

[0051] 4. Zero-pollution molten aluminum ensures the purity of aluminum alloy smelting and product quality. (1) The formula contains no harmful impurities and does not react adversely with molten aluminum. The material system eliminates harmful components such as alkali metals, alkaline earth metals, iron, and silicon, does not undergo reduction reactions with molten aluminum, and will not cause the molten aluminum to increase in iron or silicon or deteriorate. It is fully compatible with the smelting requirements of high-purity aluminum alloys and recycled aluminum alloys.

[0052] (2) Improved melt purity leads to higher aluminum yield. By avoiding contamination of molten aluminum with impurities from refractory ceramic materials, internal defects in aluminum alloy ingots and profiles are reduced by more than 30%, significantly improving the mechanical properties and surface quality of aluminum materials, and simultaneously increasing the enterprise's yield and added value.

[0053] 5. Excellent construction adaptability, no glazing required, easy maintenance, reducing on-site application costs. (1) Adaptable to both on-site casting and precast block construction methods Using a pure calcium aluminate cement bonding system, it can be directly used for overall vibration casting of aluminum furnaces on site, or it can be machine-pressed into precast blocks for masonry, making it suitable for construction in all scenarios of new furnaces, furnace repairs, and furnace renovations.

[0054] (2) No glazing required, no post-maintenance required It eliminates the need for traditional glazing processes such as spraying, brushing, and firing. It can be put into use after one molding and requires no subsequent glazing or repair, greatly reducing on-site construction difficulty, labor costs, and maintenance expenses.

[0055] (3) Easy to mold and high efficiency in mass production It can be machine-pressed or cast, with a simple molding process that requires no complex equipment, making it suitable for industrial mass production. Its production efficiency is more than 20% higher than that of traditional refractory ceramic materials.

[0056] 6. Recyclable throughout its entire lifecycle, achieving closed-loop resource utilization. (1) Waste material recycling rate ≥ 90% After the materials are scrapped, they can be directly recycled as production raw materials after simple crushing, impurity removal and screening. The recycling rate is ≥90%, which can replace 30-40% of fresh solid waste purification materials and realize the whole life cycle of "use-scrap-regeneration-reuse".

[0057] (2) No secondary solid waste is generated, and the environmental protection achieves zero emissions. The entire process of production, use, and recycling produces no wastewater, waste gas, or waste residue, completely solving the problems of difficult disposal and secondary pollution of traditional refractory ceramic materials after they are discarded. It is a truly environmentally friendly material.

[0058] 7. High-temperature performance is optimized in a synergistic manner, balancing thermal shock resistance and structural strength. (1) Gradient structure design, with optimal performance synergy The porous structure inside the material provides fracture toughness and thermal shock toughness, absorbing impact and thermal strain; the dense glaze layer on the surface provides high-temperature structural strength, surface hardness, and erosion resistance, with the internal and external components working together in a coordinated manner.

[0059] The material forms a gradient structure with internal porous thermal shock resistance and a dense, corrosion-resistant surface. It maintains excellent thermal shock resistance internally to cope with temperature fluctuations caused by frequent furnace start-ups and shutdowns; and forms a dense protective layer on the surface to block corrosion penetration, achieving a perfect balance between strength and toughness.

[0060] (2) High strength at medium and low temperatures, not easily damaged during transportation and installation. Pure calcium aluminate cement provides excellent bonding strength at medium and low temperatures. The product meets the standards for flexural strength and compressive strength at room temperature, and the damage rate during transportation and installation is reduced by more than 80%, making it suitable for the harsh handling and construction conditions in industrial sites.

[0061] 8. Outstanding economic benefits, reducing the enterprise's total lifecycle usage costs. (1) Material procurement costs reduced by 10-20% The extensive use of industrial solid waste to replace expensive natural aggregates has significantly reduced raw material costs, and the product price is 10-20% lower than that of similar high-performance refractory ceramic materials.

[0062] (2) Replacement costs and downtime losses are significantly reduced. The service life is extended by more than 50%, the replacement frequency of refractory ceramic materials is halved, and the overall cost of material procurement, labor replacement, and downtime losses for enterprises is reduced by more than 40%.

[0063] (3) Recycling further reduces costs Waste materials can be recycled and reused, further reducing raw material procurement costs and creating a sustainable cost advantage. Detailed Implementation

[0064] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0065] Example 1 This embodiment describes a method for preparing a single-atom titanium in-situ surface-strengthened refractory ceramic material, comprising the following steps: Step S1: Preparation of purified solid waste material, which includes recycled waste refractory ceramic materials and recycled secondary aluminum ash; the preparation of recycled waste refractory ceramic materials in the purified solid waste material is as follows: S11: Waste refractory bricks are coarsely crushed to a particle size ≤20mm; S12: A dry high-intensity magnetic separator with a magnetic field strength of 13000Gs is used, with a belt speed of 1.0m / s and a drum speed of 30r / min. Two-stage series magnetic separation is employed to remove elemental iron, iron oxide, and weakly magnetic iron impurities from the material, controlling the total iron impurity content of the material after magnetic separation to ≤0.1wt%. S13: Select raw materials with a particle size of 0.5-5mm by fine screening and calcine them at 1100℃ for 2 hours; S14: After cooling, recycled waste refractory ceramic materials are obtained; The preparation of secondary aluminum ash recycled material from solid waste purification is as follows: Step 1: Grind the secondary aluminum ash balls to a particle size ≤200 mesh; Step 2: Denitrification by calcination at 800℃ for 1 hour. The denitrified secondary aluminum ash powder is added to deionized water at a solid-liquid mass ratio of 1:5. The mixture is stirred at 55℃ and 300r / min for 50 minutes. After settling for 40 minutes, the salt-containing supernatant is decanted out. The lower solid-liquid mixture is coarsely filtered through a 200-mesh filter cloth plate and frame filter, then washed twice countercurrently with deionized water. Subsequently, it is finely filtered through a 300-mesh sieve to remove impurities, soluble chloride salts, fluoride salts, alkali metal salts, carbon slag, and inert impurities, resulting in a low-impurity purified aluminum ash filter cake. This cake is then calcined at 850℃ for 1 hour for activation. Step 3: After cooling, secondary aluminum ash recycled material is obtained.

[0066] Step S2: Preparation of single-atom titanium dopant, the specific steps are as follows: S21: Mix titanium oxide and aluminum oxide as raw materials in a molar ratio of 1:1; S22: The mixture is kept at 1350℃ for 3 hours; S23: Grind to a particle size ≤100nm; S24: The specific steps for preparing single-atom titanium dopant are as follows: Step S241: Preparation of alkali-free dispersion system slurry; Add 30% by weight of ultrafine titanium-aluminum composite powder to high-purity deionized water, and then compound with an alkali-free polymeric dispersant (a 1:1 mixture of citric acid and ammonium polycarboxylate). The amount of dispersant added is 2.0% of the powder mass. Stir at room temperature for 20 minutes to prepare a uniform suspension slurry.

[0067] Step S242: High-energy wet nanoball milling dissociation; The suspension slurry was fed into a ball mill, and zirconia microspheres (0.4 mm in diameter) were used as the grinding medium. The ball-to-material mass ratio was 4:1, the rotation speed was 2000 r / min, and the ball mill was circulated for 2 hours.

[0068] Step S243: Ultrasonic cavitation single-atom dissociation and dispersion; After ball milling, the slurry was transferred into an ultrasonic disperser. The ultrasonic power was set to 400W and the frequency to 30kHz. The mixture was then subjected to constant temperature ultrasonic treatment for 50 minutes. The instantaneous high pressure and micro-jet effect generated by ultrasonic cavitation further tore apart the molecular forces between particles, causing the titanium component in the titanium-aluminum composite structure to gradually dissociate into a single-atom isolated state and be uniformly suspended in the liquid phase system.

[0069] Step S244: Low-speed centrifugation to remove aggregates; The ultrasonically dispersed suspension was placed in a centrifuge and centrifuged at 3500 r / min for 10 min to separate and remove large particle agglomerates and polycrystalline agglomerates that were not completely dissociated, leaving only a stable supernatant with uniformly dispersed single-atom titanium.

[0070] Step S245: Spray drying to prevent agglomeration and curing; The supernatant after classification is sent to a spray dryer with an inlet air temperature of 200℃ and an outlet air temperature of 100℃ to obtain ultrafine powder through atomization drying.

[0071] Step S246: Low-temperature lattice anchoring in an inert atmosphere; The spray-dried powder was placed in a tube furnace, and a high-purity nitrogen / argon inert atmosphere was introduced. The temperature was increased to 500℃ at 4℃ / min, and the temperature was held for 2 hours before being cooled with the furnace to obtain a single-atom titanium dopant.

[0072] Step S3: Ingredient preparation and mixing; Weigh the following by weight percentage: 38% recycled waste refractory ceramic materials, 22% recycled secondary alumina ash, 18% mullite aggregate, 2.0% monatomic titanium dopant, 5% pure calcium aluminate cement with 85% Al2O3 content, and 5% alkaline earth silicate and titanate composite regulator; the regulator is composed of calcium metasilicate and calcium titanate compounded in a 1:1 mass ratio. Dry mix all raw materials in a high-strength mixer for 12 minutes; then add 7% (by weight of total raw materials) of recycled clean water and continue wet mixing for 10 minutes to produce a mixture that can be vibrated for casting and machine-pressed.

[0073] Step S4: The mixture is formed into a molded blank; the mixture is added to the mold, and the pressure is maintained at 20MPa for 40 minutes to obtain a standard refractory brick. The obtained standard refractory brick is a molded blank.

[0074] Step S5: The shaped green body is left to cure at room temperature and then demolded to obtain a shaped green body; the shaped green body is sent into a kiln for firing, and after cooling, a refractory ceramic material with in-situ surface strengthening of single-atom titanium is obtained. The specific steps are as follows: S51: The formed blank is left to cure at room temperature for 24 hours, and then demolded to obtain a shaped blank; S52: The shaped green body is fed into the kiln and heated to 1300℃ at 5℃ / min, held for 3 hours, and then naturally cooled to room temperature to obtain a refractory ceramic material with in-situ surface strengthening of single-atom titanium.

[0075] Application Example 1 This application example provides a specific application of the single-atom titanium in-situ surface-strengthened refractory ceramic material prepared in Example 1. When the single-atom titanium in-situ surface-strengthened refractory ceramic material is used in aluminum alloy melting furnaces, holding furnaces, and waste aluminum recycling furnaces, a continuous and dense glaze layer is generated in-situ within 10-30 minutes under working conditions of ≥1250℃.

[0076] 1. Verification of glaze density Test standard: GB / T 2997-2015 "Test methods for bulk density, apparent porosity and true porosity of dense shaped refractory products".

[0077] Testing instruments: high-temperature tubular atmosphere furnace, electronic analytical balance, Archimedes density meter, metallographic microscope. Test method: The sample was placed in a high-temperature tube furnace to simulate the constant temperature condition of an aluminum furnace at 1250℃. The onset time and complete glazing time of the surface glaze were observed in real time using a metallographic microscope. The volume density and porosity of the self-generated glaze were tested using the Archimedes displacement method, and the glaze density was calculated.

[0078] Actual test results: The sample formed a continuous, complete and dense glaze layer in 15-25 minutes at 1250℃; the measured density of the glaze layer was 98.6%, which meets the ≥98% index and can completely seal the interconnected pores of the matrix.

[0079] 2. Thermal shock stability performance verification Test standard: GB / T 30873-2014 "Refractories Thermal Shock Test Method".

[0080] Testing instruments: intelligent high-temperature muffle furnace, air-cooled thermal shock tester, stereo microscope.

[0081] Test method: The test adopted a high temperature of 1100℃ → room temperature air cooling rapid cooling and heating cycle. Each cycle was held at high temperature for 30 minutes and then air cooled to room temperature. After the cycle was completed, the cracking and peeling of the glaze and the substrate were observed using a stereomicroscope.

[0082] Actual test results: After 100 thermal shock cycles, the self-generated glaze layer on the sample surface showed no cracking, peeling, or flaking, and there was no delamination at the glaze-base interface, indicating excellent thermal shock compatibility.

[0083] 3. Verification of the anti-permeation properties of molten aluminum and molten salt Test standard: GB / T 39146-2020 Refractory materials - Test method for resistance to erosion of molten aluminum alloy.

[0084] Testing instruments: aluminum melt permeation crucible test furnace, scanning electron microscope (SEM), image analyzer.

[0085] Test method: The sample was made into a crucible sample, molten industrial pure aluminum was poured in, and it was kept at a constant temperature of 815 for 72 hours. The sample was cut open and the penetration depth and penetration channel of the aluminum liquid were observed by scanning electron microscopy. The penetration rate reduction was calculated by comparing it with traditional high-alumina refractory materials.

[0086] Actual test results: The penetration rate of aluminum liquid and molten salt in the material of this invention is reduced by 91% compared with traditional materials, effectively preventing the problems of expansion, cracking and pulverization caused by aluminum liquid penetration.

[0087] 4. Verification of resistance to molten aluminum corrosion and molten salt corrosion Test standard: GB / T 17674-2012 "Test method for resistance to molten metal erosion of refractory products" Testing instruments: High-temperature erosion test furnace, laser particle size and morphology analyzer Test method: Static aluminum liquid immersion etching method was adopted, and the samples were etched at a constant temperature of 1250℃ for 100h. The thickness of the etched layer was measured and the etching rate was calculated. Corrosion comparison test was carried out simultaneously using fluoride molten salt commonly used in aluminum furnaces.

[0088] Actual test results: The static aluminum melt erosion rate of the material of this invention is reduced by 62% compared with traditional materials, and the resistance to molten salt corrosion is improved by 53%.

[0089] 5. Service life verification Testing Standard: Enterprise Standard for Service Evaluation of Refractory Linings in Industrial Applications of Aluminum Smelting Furnaces.

[0090] Testing instruments: furnace body infrared thermometer, wall thickness gauge, and industrial operating condition online monitoring system.

[0091] Test method: The material of this invention and traditional high-alumina refractory materials were applied to aluminum alloy melting furnaces and holding furnaces of the same specifications, respectively. The erosion thickness and cracking and spalling of the furnace lining were continuously tracked, and the complete service cycle was statistically analyzed.

[0092] Actual test results: Traditional refractory materials have a service life of 6 to 12 months, while the material of this invention has a stable service life of 12 to 18 months, which is more than 50% longer than that of traditional materials, and there are no safety hazards such as furnace penetration or aluminum leakage.

[0093] 6. Waste material recycling rate Test methods: Statistically analyze the amount of solid waste added per ton of product and the amount of solid waste disposed of; after crushing, removing impurities, and screening the scrapped refractory materials, re-blend them into production, test the proportion of recycled materials and the stability of material performance, and calculate the recycling rate.

[0094] Actual test results: The waste material recycling rate of this invention reaches 92%, which can replace 30% to 40% of fresh solid waste purification materials, realizing closed-loop utilization throughout the entire life cycle.

[0095] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A refractory ceramic material with in-situ surface strengthening of single-atom titanium, characterized in that, The raw materials comprise the following percentages by weight: 55-75% purified solid waste, 15-25% refractory aggregate, 0.5-3% single-atom titanium dopant, 4-8% binder, and 3-7% regulator; the purified solid waste includes recycled waste refractory ceramic materials and recycled secondary alumina ash; the refractory aggregate is selected from high-alumina aggregate or mullite aggregate; the single-atom titanium dopant is a titanium oxide-alumina intermetallic compound oxide; the binder is pure calcium aluminate cement with an AlO content ≥70%; and the regulator is an alkaline earth silicate-titaniumate composite agent.

2. The refractory ceramic material with single-atom titanium in-situ surface strengthening according to claim 1, characterized in that, The proportions of recycled waste refractory ceramic materials and recycled secondary alumina ash in refractory ceramic materials are 30-45% and 20-30%, respectively; the recycled waste refractory ceramic materials are obtained by crushing, removing iron, screening, and calcining and activating waste high-alumina or mullite refractory bricks; the recycled secondary alumina ash is obtained by denitrifying, desalting, removing impurities, and calcining and activating secondary alumina ash from the aluminum industry at 800-900℃.

3. The refractory ceramic material with single-atom titanium in-situ surface strengthening according to claim 1, characterized in that, The single-atom titanium dopant is synthesized in a solid phase at 1300-1400℃ using titanium oxide and aluminum oxide as raw materials.

4. The refractory ceramic material with single-atom titanium in-situ surface strengthening according to claim 3, characterized in that, The solid-phase synthesized product is ground to a particle size ≤100nm and then dispersed at the atomic level to obtain titanium oxide-alumina intermetallic compound oxide, i.e., single-atom titanium dopant.

5. The method for preparing the single-atom titanium in-situ surface-strengthened refractory ceramic material according to any one of claims 1-4, characterized in that, Includes the following steps: Step S1: Preparation of purified solid waste material; Step S2: Preparation of single-atom titanium dopant; Step S3: Ingredient preparation and mixing; Weigh out the solid waste purification material, refractory aggregate, single-atom titanium dopant, binder, and regulator according to the formula, put them into a high-strength mixer and dry mix for 10-15 minutes; add 4-10% recycled clean water and wet mix for 8-12 minutes to make a mixture that can be vibrated and cast or machine-pressed. Step S4: The mixture is formed into a preform; Step S5: The shaped green body is left to cure at room temperature and demolded to obtain a shaped green body; the shaped green body is sent into a kiln for firing, and after cooling, a refractory ceramic material with in-situ surface strengthening of single-atom titanium is obtained.

6. The method according to claim 5, characterized in that, The preparation of recycled waste refractory ceramic materials in step S1 of solid waste purification is as follows: S11: Waste refractory bricks are coarsely crushed to a particle size ≤20mm; S12: Iron removal; S13: Select raw materials with a particle size of 0.5-5mm by fine screening and calcine them at 1000-1100℃ for 2 hours; S14: After cooling, recycled waste refractory ceramic materials are obtained; The preparation of secondary aluminum ash recycled material from solid waste purification is as follows: Step 1: Grind the secondary aluminum ash balls to a particle size ≤200 mesh; Step 2: After denitrification, water washing and desalination, and filtration to remove impurities, calcination and activation at 800–900℃ for 1 hour; Step 3: After cooling, secondary aluminum ash recycled material is obtained.

7. The method according to claim 5, characterized in that, The preparation steps for the single-atom titanium dopant in step S2 are as follows: S21: Mix titanium dioxide and aluminum oxide as raw materials in a molar ratio of 1:0.6-1:1.3; S22: The mixture is kept at 1300-1400℃ for 3 hours; S23: Grind to a particle size ≤100nm; S24: Single-atom titanium dopant prepared by single-atom-level dispersion treatment.

8. The method according to claim 5, characterized in that, Step S4: Select one of the following molding methods: ① Machine pressing: The mixture is added to the mold, and the pressure is maintained at 15-25MPa for 30-60s to obtain standard refractory bricks; ② Vibration casting molding: The mixture is injected into the aluminum furnace mold and vibrated to compact it, thus producing an integral cast precast part / on-site cast furnace lining; The standard refractory bricks or integral cast-in-place precast parts / on-site cast-in-place furnace linings produced are all pre-formed blanks.

9. The method according to claim 5, characterized in that, The specific steps of step S5 are as follows: S51: The formed blank is left to cure at room temperature for 24-48 hours, and then demolded to obtain a shaped blank; S52: The shaped green body is fed into the kiln and heated to 1250-1400℃ at 5℃ / min, held for 2-3 hours, and then naturally cooled to room temperature to obtain a refractory ceramic material with in-situ surface strengthening of single-atom titanium.

10. The application of the refractory ceramic material with in-situ surface reinforcement of single-atom titanium as described in any one of claims 1-4 or the refractory ceramic material with in-situ surface reinforcement of single-atom titanium prepared according to any one of claims 5-9, characterized in that: When refractory ceramic materials with in-situ surface strengthening of single-atom titanium are used in aluminum alloy smelting furnaces, holding furnaces, and waste aluminum recycling furnaces, a continuous and dense glaze layer is generated in-situ within 10-30 minutes under working conditions of ≥1250℃.