Chromium oxide refractory and method for producing the same

Abstract

The application relates to the technical field of refractory materials, in particular to a chromium oxide refractory material and a preparation method thereof. The chemical composition of the chromium oxide refractory material comprises, in percentage by weight, Cr2O3 91%-92.5%, ZrO2 2.0%-3.0%, TiO2 3.5%-4.3%, MgO and Al2O3 0.8%-1.6%, and inevitable impurities <1%. The chromium oxide refractory material has the advantages of high compactness and low sublimation. 3 91%‑92.5%, ZrO2 2.0%‑3.0%, TiO2 3.5%‑4.3%, MgO and Al2O3 0.8%‑1.6%, and inevitable impurities <1%. The chromium oxide refractory material has the advantages of high compactness and low sublimation.

Description

Technical Field

[0001] This application relates to the field of refractory materials technology, and in particular to chromium oxide refractory materials and their preparation methods. Background Technology

[0002] Chromium oxide (Cr2O3) bricks are currently the only refractory materials that can simultaneously resist the high-temperature erosion of molten glass fibers and prevent the generation of harmful bubbles, and therefore are widely used in large-scale glass fiber kilns.

[0003] With the development of fuel technology for fiberglass kilns, the industry generally adopts natural gas as the main fuel, supplemented by pure oxygen combustion technology. Some cutting-edge technologies have begun to explore hydrogen energy applications, such as new fuel schemes like natural gas blended with hydrogen. Both natural gas and hydrogen produce a large amount of water vapor (H2O) upon combustion, with hydrogen combustion producing a more significant amount of water vapor.

[0004] However, existing chromium oxide bricks have serious defects in the kiln environment, especially in the area above the glass melt line, where there is a significant "sublimation" phenomenon, which is particularly serious in the environment of the arch combustion process. The sublimation problem of chromium oxide bricks usually includes two aspects: (1) high-temperature volatilization, which refers to the reaction of Cr2O3 with water vapor (H2O), oxygen (O2), etc. in the kiln atmosphere at high temperature and in a specific atmosphere to generate gaseous chromium hydroxy compounds (such as CrO2(OH)2) or chromates (such as CrO3). The boiling point of these gaseous substances is much lower than that of Cr2O3, so they will volatilize from the surface of the brick. The high temperature volatilization causes gaseous chromium compounds to continuously escape from the surface of the brick. These gaseous substances will re-condense into loose solid particles in the relatively static area inside the kiln and deposit on the surface of the refractory brick and the inner wall of the kiln. (2) Chemical erosion refers to the combination of alkaline components (such as Na2O and K2O) in the glass melt with a large amount of water vapor generated by the kiln combustion. The alkaline vapor formed reacts with Cr2O3 to generate soluble chromates, which leads to the erosion and dissolution of the brick. Chemical erosion causes the Cr2O3 component in the brick to be directly lost, the brick structure is destroyed, and the strength decreases.

[0005] The combined effects of high-temperature volatilization and chemical erosion lead to the continuous loss of Cr2O3 from the brick, a process collectively known as "sublimation." Sublimation has the following serious consequences: ① Deterioration of the brick structure, making the surface porous and weak, and more susceptible to penetration and erosion by molten glass, thus reducing the service life of chromium oxide bricks and the overall lifespan of the kiln; ② The condensed loose particles easily fall and contaminate the glass, especially the molten glass in the channels, which is difficult to remove, forming glass defects and reducing the yield; ③ The volatilized chromium compounds (especially hexavalent chromium) are toxic and cause environmental pollution when emitted with flue gas. Therefore, "low sublimation" is a key indicator for evaluating high-quality chromium oxide bricks.

[0006] Currently, there are two main technical approaches to reducing the sublimation rate of chromium oxide bricks: one is to reduce porosity through densification; the other is to introduce more other substances (such as ZrO2 or Al2O3). However, while the former can reduce porosity to extremely low levels, it usually leads to a significant decrease in thermal shock resistance, making it difficult to adapt to the industrial environment of glass furnace production. The latter, by introducing more than 5% ZrO2 or Al2O3, can reduce the sublimation rate, but it will significantly reduce the glass erosion resistance of chromium oxide bricks. Furthermore, these substances with poor glass erosion resistance can integrate into the glass, potentially causing other defects in the glass.

[0007] Therefore, existing technologies cannot effectively suppress the sublimation of chromium oxide bricks in high-temperature and high-moisture environments while maintaining their high resistance to glass erosion, thus limiting kiln life, glass yield, and environmental protection levels.

[0008] To address the aforementioned issues, there is an urgent need to develop a high-density chromium oxide refractory material that combines excellent resistance to glass erosion with a low sublimation rate without reducing the content of the main chromium oxide component. Summary of the Invention

[0009] To overcome the above-mentioned shortcomings of the prior art, this application provides a chromium oxide refractory material and a method for preparing the same, which has the advantages of high density and low sublimation.

[0010] The first aspect of this application provides a chromium oxide refractory material, which comprises, by weight percentage: Cr2O3 91%-92.5%, ZrO2 2.0%-3.0%, TiO2 3.5%-4.3%, MgO and Al2O3 sum 0.8%-1.6%, and unavoidable impurities ≤1%.

[0011] In some embodiments, the chromium oxide refractory material comprises synthetic chromium oxide aggregate particles and a matrix phase filled between the synthetic chromium oxide aggregate particles;

[0012] The synthetic chromium oxide aggregate particles are pre-synthesized composite solid solutions, whose chemical composition includes Cr2O3, ZrO2, TiO2, MgO and Al2O3;

[0013] The matrix phase is formed by sintering matrix particles;

[0014] The matrix particles include a first particle and a second particle; the first particle has a chemical composition of Al2O3; the second particle has a chemical composition of Cr2O3.

[0015] The first particle is wrapped around the surface of the second particle.

[0016] In some embodiments, the particle size ratio of the synthetic chromium oxide aggregate particles to the matrix particles is 1.5 to 25.

[0017] In the matrix particles, the ratio of the particle size D50 of the second particle to that of the first particle is 2 to 12.

[0018] In some embodiments, the synthetic chromium oxide aggregate particles include a first synthetic chromium oxide aggregate particle, a second synthetic chromium oxide aggregate particle, and a third synthetic chromium oxide aggregate particle;

[0019] The particle size of the first synthetic chromium oxide aggregate particles is d1, where 100μm≤d1<300μm;

[0020] The particle size of the second synthetic chromium oxide aggregate particles is d2, 50μm≤d2<100μm;

[0021] The particle size D50 of the third synthetic chromium oxide aggregate particles is d3, where 15μm≤d3≤30μm.

[0022] In some embodiments, the weight ratio of the first synthetic chromium oxide aggregate particles, the second synthetic chromium oxide aggregate particles, and the third synthetic chromium oxide aggregate particles is (5-20):(5-12):(10-15).

[0023] In some embodiments, the particle size D50 of the first particle is d4, where 1μm≤d4≤3μm;

[0024] The particle size D50 of the second particle is d5, where 7μm≤d5≤12μm.

[0025] In some embodiments, the synthetic chromium oxide aggregate particles comprise, by weight percentage: Cr2O3 94%-95%, TiO2 3.0%-4.5%, ZrO2 0.5%-1.5%, the sum of Al2O3 and MgO 0.5%-1.5%, and unavoidable impurities ≤1%.

[0026] In some embodiments, the weight ratio of Al2O3 in the first particle to Cr2O3 in the second particle is (0.05-0.1):1.

[0027] In some embodiments, the chemical composition of the first particle further includes one or more of ZrO2, TiO2, and MgO.

[0028] In some embodiments, the weight ratio of Al2O3, ZrO2, TiO2 and MgO in the first particle is 1:(3-5):(3-5):(0-0.5).

[0029] In some embodiments, the chromium oxide refractory material comprises, by weight percentage: 10%-40% of the synthetic chromium oxide aggregate particles, 5%-10% of the first particles, and 50%-80% of the second particles.

[0030] The second aspect of this application provides a method for preparing chromium oxide refractory materials, wherein the chemical composition of the chromium oxide refractory materials comprises, by weight percentage: Cr2O3 91%-92.5%, ZrO2 2.0%-3.0%, TiO2 3.5%-4.3%, MgO and Al2O3 sum 0.8%-1.6%, and unavoidable impurities ≤1%;

[0031] The preparation method includes the following steps:

[0032] After mixing the first Cr2O3 source powder, the first TiO2 source powder, the first ZrO2 source powder, the first MgO source powder and the first Al2O3 source powder, water and the first binder are added, mixed and ground to obtain aggregate slurry;

[0033] The aggregate slurry is dried, shaped, pre-fired at 1580℃-1630℃ in a reducing atmosphere, crushed, and sieved to obtain synthetic chromium oxide aggregate particles.

[0034] The first particles and the second binder are mixed and ground to obtain a first matrix slurry; the first particles include a second Al2O3 source powder.

[0035] The second particle is added to the first matrix slurry and mixed to obtain the second matrix slurry; the second particle includes the second Cr2O3 source powder.

[0036] Synthetic chromium oxide aggregate particles and a third binder are added to the second matrix slurry and mixed to obtain molding material slurry;

[0037] The molding slurry is dried, shaped, and calcined at 1610℃-1630℃ in a reducing atmosphere and kept at that temperature to obtain the chromium oxide refractory material.

[0038] In some embodiments, in the step of preparing the first synthetic chromium oxide aggregate particles, after sieving, synthetic chromium oxide aggregate particles of different particle sizes are obtained, including the first synthetic chromium oxide aggregate particles, the second synthetic chromium oxide aggregate particles and the third synthetic chromium oxide aggregate particles.

[0039] The particle size of the first synthetic chromium oxide aggregate particles is d1, where 100μm≤d1<300μm;

[0040] The particle size of the second synthetic chromium oxide aggregate particles is d2, 50μm≤d2<100μm;

[0041] The particle size D50 of the third synthetic chromium oxide aggregate particles is d3, 15μm≤d3≤30μm;

[0042] In the step of mixing the synthetic chromium oxide aggregate particles and the third binder into the second matrix slurry, the third synthetic chromium oxide aggregate particles are added first and then mixed, followed by the third binder and then the second synthetic chromium oxide aggregate particles and the first synthetic chromium oxide aggregate particles are added and mixed.

[0043] In some embodiments, the third synthetic chromium oxide aggregate particles and the third binder are mixed by interleaving.

[0044] In some embodiments, the first adhesive, the second adhesive, and the third adhesive each independently comprise one or more of dextrin, sodium carboxymethyl cellulose, silica sol, and an aqueous solution of polyvinyl alcohol.

[0045] In some embodiments, the grinding ball ratio is ≤1.25.

[0046] In some embodiments, the molding method includes isostatic pressing, with a pressure of 200MPa-240MPa and a holding time of 10min-20min.

[0047] In some embodiments, the drying method includes spray drying, and the moisture content of the dried material is ≤0.5%.

[0048] In some embodiments, the heat preservation time is 24h-30h.

[0049] Compared with the prior art, the chromium oxide refractory material of this application has at least the following advantages:

[0050] (1) The chromium oxide refractory material of this application, through a unique composition design, maintains a high Cr2O3 content (≥91%) and excellent resistance to glass erosion, while significantly reducing its sublimation rate under an oxidizing atmosphere, thereby extending the service life of the kiln, increasing the glass yield, and reducing environmental pollution. In some preferred embodiments, through the synergistic design of "synthetic aggregate pre-homogenization" and "ultrafine powder coating", a more stable phase is formed in the brick body. The first particle (ultrafine powder, containing Al2O3) is richly coated on the surface of the second particle (Cr2O3 coarse powder), forming a protective layer with extremely high chemical stability. This protective layer can effectively block Cr2O3 from direct contact with water vapor and oxygen in the atmosphere, thereby inhibiting the oxidation and volatilization of chromium.

[0051] (2) The preparation method of the chromium oxide refractory material of this application mainly uses high-content Cr2O3 (≥91%) as the main component and achieves high density through high-temperature sintering (1610℃-1630℃). In some preferred embodiments, the apparent porosity can be ≤2.5% and the bulk density can be ≥4.70g / cm³. 3 The chromium oxide refractory material has an E-glass erosion resistance index of no less than 95% of that of ordinary high-quality chromium bricks, and its performance is even better when it is denser. It overcomes the defect of existing technology that leads to a decrease in erosion resistance due to the introduction of too many other components (such as Al2O3).

[0052] (3) The preparation method of the chromium oxide refractory material of this application is suitable for industrial production, with good process controllability. It can be widely used in areas above the liquid level line of glass fiber kilns, such as the arch, which are in contact with high water vapor atmosphere. It is suitable for kiln environments using new fuel technologies such as natural gas with hydrogen or pure hydrogen combustion, and has good economic benefits and environmental value. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0054] Figure 1 This is a comparison image of the chromium oxide refractory material prepared in Example 3 of this application before and after the antioxidant sublimation test.

[0055] Figure 2 These are comparison photos of the chromium oxide refractory materials prepared in Examples 1, 1, 2, and 2 of this application before and after the glass melt erosion resistance test.

[0056] Figure 3 The image shows an electron microscope image of the surface of the chromium oxide refractory material prepared in Example 1 of this application, with a scale bar of 300 μm.

[0057] Figure 4 The image shows an electron microscope image of the surface of the chromium oxide refractory material prepared in Example 2 of this application. The scale bar is 300 μm.

[0058] Figure 5 The image shows an electron microscope image of the surface of the chromium oxide refractory material prepared in Example 3 of this application. The scale bar is 300 μm. Detailed Implementation

[0059] The present application is further described below with reference to embodiments and examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Furthermore, it should be understood that after reading the teachings of this application, those skilled in the art can make various alterations or modifications to this application, and these equivalent forms also fall within the protection scope of the appended claims.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0061] The term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" includes three parallel options: A, B, and A+B.

[0062] In this article, the terms "multiple" and "various kinds" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more kinds.

[0063] In this document, "preferred" is only used to describe a better implementation method or embodiment, and should be understood as not constituting a limitation on the scope of protection of this application.

[0064] In this document, "furthermore" is used to describe the purpose and indicate differences in content, but should not be construed as a limitation on the scope of protection of this application.

[0065] In this article, "optionally" means optional, that is, it refers to either "with" or "without". If a technical solution has multiple "options", unless otherwise specified, and there are no contradictions or mutual constraints, then each "option" is independent.

[0066] In this article, the terms "first aspect," "second aspect," etc., are used for descriptive purposes only and should not be interpreted as indicating or implying relative importance or quantity, nor should they be interpreted as implicitly specifying the importance or quantity of the indicated technical features. Moreover, "first," "second," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0067] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0068] In this document, numerical intervals (i.e., numerical ranges) are referred to. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0069] Unless otherwise specified, the temperature parameters in this document are permitted to be either constant-temperature treatment or vary within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, and ±1℃.

[0070] In this article, "enrichment" refers to the phenomenon that, at the microscale, the distribution density of the first particle on the surface of the second particle is significantly higher than that in other areas of the material. This selective distribution can be achieved through a specific feeding sequence and mixing process. For example, the powder that makes up the first particle can be made into a slurry first, and then the second particle can be added into it and mixed so that the first particle is uniformly wrapped on the surface of the second particle. After sintering, a continuous zirconium-rich protective micro-region is formed.

[0071] In this article, "complex solid solution" refers to a mixture of multiple cations (Cr). 3+ Al 3+ Zr 4+ Ti 4+ A solid solution formed by the coexistence of chromium, chromium, and other elements in the same oxide lattice is typically (Cr,Al,Zr,Ti)₂O₃. The formation of a composite solid solution makes the Cr₂O₃ lattice more stable and less likely to react with water vapor and oxygen in the atmosphere, thereby inhibiting the volatilization of chromium.

[0072] In this article, "Cr2O3 source powder" refers to raw material powder with Cr2O3 as the main component, including but not limited to industrial chromium oxide green and high-purity chromium oxide powder. Depending on the application scenario or physical properties such as particle size, it is divided into first Cr2O3 source powder (used for synthesizing aggregates) and second Cr2O3 source powder (used for matrix phase).

[0073] In this article, "TiO2 source powder" refers to raw material powder with TiO2 as the main component, including but not limited to titanium dioxide, anatase or rutile titanium dioxide, etc.

[0074] In this article, "ZrO2 source powder" refers to raw material powder with ZrO2 as the main component, including but not limited to industrial zirconium oxide powder and zircon powder (ZrSiO4). When zircon powder is used, the ZrO2 and SiO2 introduced are included in the ZrO2 content and SiO2 is included in the unavoidable impurities.

[0075] In this article, "MgO source powder" refers to raw material powder with MgO as the main component, including but not limited to industrial magnesium oxide powder and lightly calcined magnesium oxide.

[0076] In this article, "Al2O3 source powder" refers to raw material powder with Al2O3 as the main component, including but not limited to industrial alumina powder and calcined alumina micro powder.

[0077] In this article, "magnesium aluminum spinel powder" refers to a raw material powder with MgAl2O4 as the main component, which can be pre-synthesized from MgO and Al2O3. In some embodiments, it is introduced as a component of the first particle.

[0078] In this article, "pre-firing" refers to the first heat treatment of the synthetic aggregate raw material before final sintering. In some embodiments, the pre-firing temperature (1580℃-1630℃) is lower than the final sintering temperature (1610℃-1630℃), which can cause the aggregate raw material to undergo a solid-phase reaction to form a composite solid solution and obtain a stable phase structure.

[0079] In this article, "calcination" refers to the final heat treatment of the formed green body, i.e., sintering in the conventional sense. In some embodiments, it refers to the process of holding at 1610℃-1630℃ for 24h-30h to make the chromium oxide refractory material achieve ultra-high density and have the corresponding properties of refractory materials.

[0080] In this article, "reducing atmosphere" refers to an atmospheric environment where the oxygen partial pressure is lower than that of atmospheric oxygen, such as a hydrogen atmosphere, a carbon monoxide atmosphere, or a mixture thereof. Sintering under a reducing atmosphere can prevent Cr2O3 from being oxidized to high-valent chromium.

[0081] In this article, "material-to-ball ratio" refers to the ratio of the total weight of the material input to the total weight of the grinding media (stones) during the grinding process. A material-to-ball ratio ≤1.25 (preferably ≤1:0.8) can ensure grinding efficiency and mixing uniformity.

[0082] In this article, "isostatic pressing" refers to a molding method in which an isostatic pressure is applied to the molding material in a closed liquid or gas medium. In some embodiments, a molding pressure of 200MPa-240MPa is used, which is 2-3 times the conventional molding pressure, so that the green body achieves ultra-high density.

[0083] In this article, "spray drying" refers to a method of dispersing slurry-like materials into fine droplets through an atomizer and then drying them instantly in a hot air stream. In some embodiments, spray drying is used to dry the molding slurry into a free-flowing granular molding base material with a moisture content controlled at ≤0.5%.

[0084] In this article, "unavoidable impurities" refers to trace components that are naturally present in the raw materials or unavoidably introduced during the preparation process and are not intentionally added, including but not limited to SiO2, Fe2O3, Na2O, K2O, CaO, etc., whose total content does not exceed 1%.

[0085] In this article, "the sum of MgO and Al2O3" or "the sum of Al2O3 and MgO" refers to the sum of the contents of the two components, MgO and Al2O3. This is because the two components may be introduced into the raw materials at the same time, and the total amount of the two components can be controlled between 0.8% and 1.6% to meet the performance requirements of chromium oxide refractory materials.

[0086] In this article, "apparent porosity" refers to the percentage of the volume of open pores in a material to the total volume of the material, determined according to the method specified in GB / T2997-2015. In some embodiments, an apparent porosity ≤2.5% indicates that the chromium oxide refractory material has ultra-high density.

[0087] In this article, "bulk density" refers to the ratio of the mass of a material to its total volume (including solid, open, and closed pores), determined according to the method specified in GB / T 2997-2015. In some embodiments, the bulk density is ≥4.70 g / cm³. 3 This proves that chromium oxide refractory materials achieve ultra-high density.

[0088] In this article, "particle size D50" refers to the particle diameter corresponding to 50% of the cumulative amount on the particle cumulative distribution curve, i.e., the median particle size. It is used to characterize the average size of powder particles.

[0089] The first aspect of this application provides a chromium oxide refractory material whose chemical composition by weight percentage includes: Cr2O3 91%-92.5%, ZrO2 2.0%-3.0%, TiO2 3.5%-4.3%, MgO and Al2O3 sum 0.8%-1.6%, and unavoidable impurities ≤1%.

[0090] The chromium oxide refractory material of this application controls the Cr2O3 content to ≥91%, ensuring excellent resistance to glass melt erosion and providing a foundation for the long-term stable use of the refractory material. By controlling the Cr2O3 content to ≤92.5%, and simultaneously controlling the ZrO2 content to 2.0%-3.0% and the TiO2 content to 3.5%-4.3%, appropriate stabilizing components are introduced. These components form a composite solid solution with Cr2O3 during sintering, improving lattice stability and thus inhibiting the high-temperature volatilization of chromium. By controlling the total amount of MgO and Al2O3 to 0.8%-1.6%, auxiliary sintering and stabilizing components are introduced while avoiding the reduction of the material's erosion resistance due to the introduction of too many heterogeneous components.

[0091] In some embodiments, the chromium oxide refractory material includes synthetic chromium oxide aggregate particles and a matrix phase filled between the synthetic chromium oxide aggregate particles;

[0092] The synthetic chromium oxide aggregate particles are pre-synthesized composite solid solutions, whose chemical composition includes Cr2O3, ZrO2, TiO2, MgO and Al2O3;

[0093] The matrix phase is formed by the sintering of matrix particles;

[0094] The matrix particles include a first particle and a second particle; the chemical composition of the first particle includes Al2O3; the chemical composition of the second particle includes Cr2O3.

[0095] The first particle is coated on the surface of the second particle.

[0096] In this embodiment, the synthetic chromium oxide aggregate particles, as a pre-synthesized composite solid solution, have a stable phase structure and excellent anti-corrosion properties, and are uniformly distributed in the material to form a load-bearing skeleton. The matrix phase fills the spaces between the synthetic chromium oxide aggregate particles and is formed by sintering the matrix particles at a suitable temperature (e.g., 1610℃-1630℃). Since the first particle containing Al2O3 in the matrix particles is wrapped around the surface of the second particle containing Cr2O3, Al2O3 can form a physical barrier on the surface of Cr2O3 during the sintering process. As the main anti-corrosion component, Cr2O3 is isolated from water vapor and oxygen in the environment under the protection of the Al2O3 protective layer, effectively inhibiting further oxidation (hexavalent chromium) and volatilization of chromium, and greatly improving the stability of the material.

[0097] In some embodiments, the particle size ratio of the synthetic chromium oxide aggregate particles to the matrix particles is 1.5 to 25. The synthetic chromium oxide aggregate particles form a stable skeletal structure, providing the main resistance to erosion; the matrix particles can uniformly fill the voids in the aggregate particles, forming a suitable particle size distribution, which is beneficial for achieving high density packing.

[0098] In some embodiments, the ratio of the particle size D50 of the second particle to that of the first particle is 2 to 12. The finer-sized second particle contains Cr2O3 and can fill between the synthetic chromium oxide aggregate particles as the main anti-corrosion component. After being mixed with the finer-sized first particle (containing Al2O3), the first particle can completely coat the surface of the second particle, forming a continuous protective layer on the surface of the second particle.

[0099] In some embodiments, the synthetic chromium oxide aggregate particles include a first synthetic chromium oxide aggregate particle, a second synthetic chromium oxide aggregate particle, and a third synthetic chromium oxide aggregate particle;

[0100] The particle size of the first synthesized chromium oxide aggregate particles is d1, where 100μm≤d1<300μm;

[0101] The particle size of the second synthesized chromium oxide aggregate particles is d2, 50μm≤d2<100μm;

[0102] The particle size D50 of the third synthetic chromium oxide aggregate particles is d3, where 15μm≤d3≤30μm.

[0103] The first synthetic chromium oxide aggregate particles form the main skeleton, the second synthetic chromium oxide aggregate further fills the voids, and the third synthetic chromium oxide aggregate particles have a smaller particle size than the matrix particles. This gradation of skeleton particles can improve the packing density, form a denser and more uniform internal structure, thereby improving the strength of the brick body, reducing the possibility of brick cracking, and improving the thermal shock resistance of the brick.

[0104] In some embodiments, the weight ratio of the first synthetic chromium oxide aggregate particles, the second synthetic chromium oxide aggregate particles, and the third synthetic chromium oxide aggregate particles is (5-20):(5-12):(10-15).

[0105] In some embodiments, the particle size D50 of the first particle is d4, where 1 μm ≤ d4 ≤ 3 μm; and the particle size D50 of the second particle is d5, where 7 μm ≤ d5 ≤ 12 μm. This particle size combination ensures that the first particle containing Al2O3 is fully coated on the surface of the second particle containing Cr2O3, and forms a reasonable particle size distribution with the above-mentioned synthetic chromium oxide aggregate particles, which is beneficial for achieving high-density packing.

[0106] In some embodiments, the synthetic chromium oxide aggregate particles comprise, by weight percentage: Cr2O3 94%-95%, TiO2 3.0%-4.5%, ZrO2 0.5%-1.5%, the sum of Al2O3 and MgO 0.5%-1.5%, and unavoidable impurities ≤1%.

[0107] In this embodiment, the chemical composition of the synthetic chromium oxide aggregate is further defined, with a Cr2O3 content as high as 94%-95%, allowing the aggregate to retain the inherent anti-corrosion properties of chromium oxide. TiO2, ZrO2, Al2O3, and MgO react fully with Cr2O3 during the pre-calcination process of the aggregate to form a (Cr,Al,Zr,Ti)2O3 composite solid solution, making the Cr2O3 lattice in the aggregate more stable and less susceptible to corrosion and volatilization during use. This ensures that the aggregate itself has excellent anti-corrosion performance and structural stability, providing a solid anti-corrosion foundation for the overall material.

[0108] In some embodiments, the weight ratio of Al2O3 in the first particle to Cr2O3 in the second particle is (0.05-0.1):1. This ensures that Al2O3 can fully encapsulate Cr2O3, forming a more complete physical barrier.

[0109] In some embodiments, the chemical composition of the first particle further includes one or more of ZrO2, TiO2, and MgO.

[0110] In this embodiment, TiO2, as a mineralizer, can promote material migration during sintering and help densify the protective layer; ZrO2 can form composite oxides or spinel phases with Al2O3 and MgO, improving the chemical stability and high-temperature strength of the protective layer. Through the synergistic effect of multiple components, the protective layer enriched on the surface of Cr2O3 source powder becomes more uniform, dense and stable, further optimizing the structure and performance of the zirconium-rich protective micro-region, thereby more effectively suppressing the volatilization of chromium.

[0111] In some embodiments, the weight ratio of Al2O3, ZrO2, TiO2 and MgO in the first particle is 1:(3-5):(3-5):(0-0.5).

[0112] In this embodiment, the addition of appropriately proportioned TiO2, Al2O3, and MgO further optimized the sintering activity and high-temperature stability of the matrix. The synergistic effect of this range of chemical compositions allows the matrix phase to not only bond well with the aggregate but also exert its unique anti-sublimation function, ensuring chemical compatibility and performance matching between the matrix phase and the aggregate.

[0113] In some embodiments, the chromium oxide refractory material comprises, by weight percentage: 10%-40% synthetic chromium oxide aggregate particles, 5%-10% first particles, and 50%-80% second particles.

[0114] In this embodiment, the synthetic chromium oxide aggregate particles account for 10%-40%, ensuring the formation of a stable skeletal structure and providing the main resistance to erosion. The first and second particles account for 5%-10% and 50%-80% respectively, jointly constituting the matrix of the material. The first particles are sufficient to provide adequate encapsulation and protection for the second particles, forming a continuous and dense protective layer, without causing excessive shrinkage or high cost due to excessive ultrafine powder. By controlling the content of each component within an appropriate range, the components can exert a synergistic effect, enabling the material to achieve optimal densification and microstructure uniformity after sintering.

[0115] In some embodiments, the apparent porosity of the chromium oxide refractory material is ≤2.5%, and the bulk density is ≥4.70 g / cm³. 3 Apparent porosity ≤ 2.5%, bulk density ≥ 4.70 g / cm³ 3 This means that the material has very few internal pores, which physically minimizes the contact area between Cr2O3 and corrosive atmospheres (water vapor, oxygen), thus significantly inhibiting the volatilization of chromium. At the same time, the high density also gives the material higher strength and better impermeability, further extending the material's service life.

[0116] In some embodiments, the chromium oxide refractory material of this application has an oxidation and sublimation resistance that is 20%-35% higher than that of ordinary dense chromium oxide bricks.

[0117] The second aspect of this application provides a method for preparing chromium oxide refractory materials, comprising the following steps:

[0118] S1. Mix the first Cr2O3 source powder, the first TiO2 source powder, the first ZrO2 source powder, the first MgO source powder and the first Al2O3 source powder, add water and the first binder, mix and grind to obtain aggregate slurry;

[0119] S2. Dry the aggregate slurry, shape it, pre-calcine it at 1580℃-1630℃ in a reducing atmosphere, crush it, and sieve it to obtain synthetic chromium oxide aggregate particles.

[0120] S3. Mix and grind the first particles and the second binder to obtain a first matrix slurry; the first particles include the second Al2O3 source powder;

[0121] S4. The second particle is added to the first matrix slurry and mixed to obtain the second matrix slurry; the second particle includes the second Cr2O3 source powder.

[0122] S5. The synthetic chromium oxide aggregate particles and the third binder are added to the second matrix slurry and mixed to obtain the molding material slurry.

[0123] S6. Dry the molding slurry, shape it, and calcine it at 1610℃-1630℃ in a reducing atmosphere, then keep it warm to obtain chromium oxide refractory material.

[0124] This preparation method can be used to prepare the chromium oxide refractory materials mentioned above.

[0125] In some embodiments, the chromium oxide refractory material prepared by this method has the characteristics of the chromium oxide refractory material described in any of the above technical solutions. For example, the chemical composition of the chromium oxide refractory material, by weight percentage, includes: Cr2O3 91%-92.5%, ZrO2 2.0%-3.0%, TiO2 3.5%-4.3%, the sum of MgO and Al2O3 0.8%-1.6%, and unavoidable impurities ≤1%.

[0126] In the preparation method of this application, chromium oxide aggregate is pre-synthesized in steps S1-S2, allowing the components in the aggregate to fully react and form a stable composite solid solution, providing a robust anti-corrosion skeleton for the material; through the specific feeding sequence in steps S3-S4—first mixing the first particles containing Al2O3 and the second binder to form a slurry, and then adding the second particles containing Cr2O3 for mixing, the first particles uniformly coat the second particles, forming a protective layer; through step S5, the coated slurry is mixed with the synthesized aggregate, so that the overall material forms a structure of "aggregate skeleton + coated matrix"; through high-temperature calcination in step S6, the components are fully sintered to achieve ultra-high density.

[0127] In some embodiments, in the step of preparing the first synthetic chromium oxide aggregate particles, after sieving, synthetic chromium oxide aggregate particles of different particle sizes are obtained, including the first synthetic chromium oxide aggregate particles, the second synthetic chromium oxide aggregate particles and the third synthetic chromium oxide aggregate particles.

[0128] The first synthetic chromium oxide aggregate particles have a particle size of d1, 100μm≤d1<300μm; they possess both a certain particle strength and good bonding with the matrix.

[0129] The particle size of the second-stage synthetic chromium oxide aggregate particles is d2, 50μm≤d2<100μm; as the second-stage aggregate particles, they can play a connecting role.

[0130] The particle size D50 of the third-synthesized chromium oxide aggregate particles is d3, 15μm≤d3≤30μm; it is closer to the particle size of the matrix particles, which further improves the bulk density of the pellet.

[0131] In the step of mixing the synthetic chromium oxide aggregate particles and the third binder into the second matrix slurry, the third synthetic chromium oxide aggregate particles are added first for mixing, then the third binder is added for mixing, and then the second synthetic chromium oxide aggregate particles and the first synthetic chromium oxide aggregate particles are added for mixing.

[0132] Using synthetic chromium oxide aggregate particles of different sizes in combination can create rich particle layers, providing excellent bonding and filling effects. Feeding these synthetic chromium oxide aggregate particles of different sizes in a "fine-to-coarse" manner improves the uniformity and density of particle mixing, thereby enhancing the strength and corrosion resistance of the brick body, reducing the likelihood of brick cracking, and improving the brick's thermal shock resistance.

[0133] In some embodiments, the third synthetic chromium oxide aggregate particles and the third binder are added alternately for mixing. Since the third synthetic chromium oxide aggregate particles are the first "skeleton" component added, and their particle size differs significantly from that of the extremely fine matrix particles, the method of adding them alternately with the third binder can better mix the two types of particles with different particle sizes and functions evenly.

[0134] In some embodiments, the particle size D50 of the first Cr2O3 source powder, the first TiO2 source powder, the first ZrO2 source powder, the first MgO source powder, and the first Al2O3 source powder is ≤3μm. As powders with the above-mentioned particle size characteristics, the components can be fully and uniformly mixed and undergo solid-phase reaction during the aggregate synthesis process, which is beneficial to obtaining a dense structure and giving the chromium oxide refractory material stronger structural stability and erosion resistance.

[0135] In some embodiments, the particle size D50 of the second Al2O3 source powder is ≤3μm; the particle size D50 of the second Cr2O3 source powder is 7μm-12μm. As a powder with the above-mentioned particle size characteristics, the ultrafine particle size of the second Al2O3 source powder has high surface activity and good flowability, and can uniformly coat the surface of the second Cr2O3 source powder. The second Cr2O3 source powder, as the core particle being coated, can provide sufficient Cr2O3 content and has a moderate specific surface area, which facilitates the uniform adhesion of the ultrafine powder. This embodiment achieves better particle size distribution and reactivity by precisely controlling the particle size of each raw material.

[0136] In some embodiments, the first particle further includes one or more of the second ZrO2 source powder, the second TiO2 source powder, and the second MgO source powder.

[0137] In some embodiments, the particle size D50 of the second ZrO2 source powder, the second TiO2 source powder, and the second MgO source powder is ≤3μm.

[0138] In some embodiments, the first binder, the second binder, and the third binder each independently comprise one or more of dextrin, sodium carboxymethyl cellulose, silica sol, and an aqueous solution of polyvinyl alcohol. These binders ensure the molding properties and green strength of the molding compound and are completely decomposed during calcination without affecting the product's performance.

[0139] In some embodiments, the ball-to-particle ratio is ≤1.25. Using the above ball-to-particle ratio ensures grinding efficiency and mixing uniformity.

[0140] In some embodiments, the molding method includes isostatic pressing, with a pressure of 200 MPa-240 MPa and a holding time of 10 min-20 min. This pressure is 2-3 times that of conventional molding pressure, and combined with the 10 min-20 min holding time, it enables the green body to achieve higher density and helps to reduce porosity.

[0141] In some embodiments, the drying method includes spray drying, and the moisture content of the dried material is ≤0.5%. This moisture content ensures the flowability and molding performance of the molding compound.

[0142] In some embodiments, the holding time is 24-30 hours. A suitable holding time is beneficial for the full sintering and grain development of the material, enabling the material to achieve the best densification effect.

[0143] The following are some specific examples.

[0144] For experimental parameters not specified in the following specific embodiments, please refer to the guidelines given in this application document first, or refer to experimental manuals or other experimental methods known in the art, or refer to the experimental conditions recommended by the manufacturer.

[0145] The raw materials and reagents involved in the following specific embodiments can be obtained commercially or prepared by those skilled in the art using known methods.

[0146] I. Testing Methods

[0147] The performance testing methods involved in the embodiments and comparative examples are as follows:

[0148] 1. Apparent porosity and bulk density

[0149] The tests were conducted in accordance with GB / T 2997-2015 Test Methods for Bulk Density, Apparent Porosity and True Porosity of Dense Shaped Refractory Products. Apparent porosity refers to the percentage of the volume of open pores in the product to the total volume of the product; bulk density refers to the ratio of the mass of the product to the total volume of the product (including solids, open pores and closed pores).

[0150] 2. Resistance to molten glass corrosion test

[0151] The test was conducted according to JC / T 806-2013, "Static Resistance Test Method for Refractory Materials Used in Glass Melting Furnaces to Resist Static Molten Glass Erosion". The test samples were prepared as strips and inserted into crucibles containing high-modulus glass fiber (M Glass). The crucibles were held at 1600℃ for 72 hours at a molten glass flow rate of 45 m / h. After the test, the unidirectional erosion index of the samples at the liquid surface and halfway down the liquid surface was measured using a stereomicroscope. The erosion resistance index of commercially available dense chrome bricks of Guangzhou Lingnan Refractory Materials Co., Ltd. (CR94-HD grade) was defined as 100, and the relative erosion resistance indices of other samples were calculated.

[0152] 3. Antioxidant sublimation capacity test

[0153] Currently, there is no standard test method for the oxidation and sublimation resistance of chromium oxide refractory materials used in glass furnaces; therefore, the following self-made method is adopted:

[0154] Sample size: 40mm × 40mm × 60mm cuboid, all surfaces finely ground, free of visible microcracks. The sample was dried to constant weight at 110℃ and weighed (m1). The sample was placed in a high-temperature controlled atmosphere electric furnace, with industrial oxygen (purity ≥99.2%) introduced at a flow rate of 3L / min, and held at 1600℃ for 144h (6 days). After cooling, it was weighed (m2). The absolute sublimation weight Δm = m1 - m2, and the sublimation rate wt% = (Δm / m1) × 100%. Using the sublimation rate of Comparative Example 2 as 100%, the relative sublimation rates of the other samples were calculated.

[0155] II. Examples of Synthetic Chromium Oxide Aggregates

[0156] The following examples illustrate the preparation and properties of synthetic chromium oxide aggregate particles.

[0157] Example S1

[0158] Take the raw materials according to the proportions shown in Table 1, put them into a stirred mill, add an appropriate amount of water and grind for 3 hours to obtain aggregate slurry. After drying the slurry, form it in an isostatic press at a pressure of 230 MPa for 15 minutes to obtain green compacts. Pre-fire the green compacts at 1620℃ for 12 hours in a reducing atmosphere to obtain synthetic aggregate briquettes. After crushing the briquettes, grind them in a Raymond mill and sieve them to obtain synthetic chromium oxide aggregate particles with a particle size ≤0.3 mm.

[0159] Example S2

[0160] Take the raw materials according to the proportions shown in Table 1, put them into a stirred mill, add an appropriate amount of water and grind for 3 hours to obtain aggregate slurry. After drying the slurry, form it in an isostatic press at a pressure of 200 MPa for 20 minutes to obtain green compacts. Pre-fire the green compacts at 1580℃ for 12 hours in a reducing atmosphere to obtain synthetic aggregate briquettes. After crushing the briquettes, grind them in a Raymond mill and sieve them to obtain synthetic chromium oxide aggregate particles with a particle size ≤0.3 mm.

[0161] Example S3

[0162] Take the raw materials according to the proportions shown in Table 1, put them into a stirred mill, add an appropriate amount of water and grind for 3 hours to obtain aggregate slurry. After drying the slurry, form it in an isostatic press at a pressure of 240 MPa for 10 minutes to obtain green compacts. Pre-fire the green compacts at 1630℃ for 12 hours in a reducing atmosphere to obtain synthetic aggregate briquettes. After crushing the briquettes, grind them in a Raymond mill and sieve them to obtain synthetic chromium oxide aggregate particles with a particle size ≤0.3 mm.

[0163] Comparative Example D1

[0164] Take the raw materials according to the proportions shown in Table 1, mix them, and directly press them in an isostatic press at 230 MPa for 15 minutes to obtain green compacts. Pre-fire the green compacts at 1630℃ for 12 hours in a reducing atmosphere to obtain synthetic aggregate briquettes. Crush the briquettes and grind them using a Raymond mill, then sieve to obtain synthetic chromium oxide aggregate particles with a particle size ≤0.3 mm.

[0165] Comparative Example D2

[0166] Take the raw materials according to the proportions shown in Table 1, mix them together, and pound them to obtain a green body. Pre-fire the green body at 1630℃ for 12 hours in a reducing atmosphere to obtain synthetic aggregate briquettes. Crush the briquettes and grind them using a Raymond mill, then sieve to obtain synthetic chromium oxide aggregate particles with a particle size ≤0.3mm.

[0167] Table 1 Examples and Comparative Proportions of Synthetic Chromium Oxide Aggregates

[0168]

[0169] In Table 1, “—” indicates that the component is not added. The weight percentage of the first binder is calculated as 100% of the total weight of chromium oxide powder, titanium dioxide, zircon powder, magnesium oxide powder, magnesium aluminum spinel powder, alumina powder, and silicon oxide powder. Since the first binder completely decomposes during calcination, it is not included in the total weight.

[0170] Table 2. Apparent porosity and bulk density of synthetic chromium oxide aggregate particles obtained in Examples S1-S3 and Comparative Examples D1-D2

[0171]

[0172] As shown in Table 2, the synthetic chromium oxide aggregate prepared using ultrafine raw materials and isostatic pressing (Examples S1, S2, and S3) exhibits extremely low apparent porosity (≤1.9%) and high bulk density (≥4.82 g / cm³). 3 When coarser raw materials or lower molding pressure are used in the comparison ratio, the porosity of the aggregate increases significantly, resulting in a decrease in density.

[0173] III. Examples of Chromium Oxide Refractory Materials

[0174] The following examples illustrate the preparation and properties of the chromium oxide refractory material of this application. Examples 1-3 below use the synthetic chromium oxide aggregate particles obtained in Examples S1-S3 above, and the particles are further sieved and artificially graded with matrix particles. The specific formulations are shown in Table 3.

[0175] Example 1

[0176] (1) Take the raw materials of chromium oxide refractory material according to Table 2, wherein the first synthetic chromium oxide aggregate particles and the second synthetic chromium oxide aggregate particles are the corresponding raw materials obtained in Example S1.

[0177] (2) Add the components of the first particle into a stirring mill, add the first binder, with a particle-to-ball ratio of 1:0.8, grind for 5 minutes to obtain a mixed slurry.

[0178] (3) Add the second particle (chromium oxide green coarse powder) into the above mixed slurry and continue grinding for 15 minutes to make the ultrafine slurry evenly coat the surface of the coarse powder to obtain the coated mud.

[0179] (4) Mix the coating slurry with the first synthetic chromium oxide aggregate particles, add the second binder, and mix in a vacuum mixing tank for 30 minutes to obtain the molding slurry.

[0180] (5) Spray dry the molding material slurry, control the moisture content to ≤0.5%, and pass it through a 20-mesh sieve to obtain the molding base material.

[0181] (6) The molding base material is molded in an isostatic press at a pressure of 220MPa and held for 15 minutes to obtain a green blank.

[0182] (7) The green billet is calcined at 1620°C in a reducing atmosphere and held for 28 hours to obtain a refractory billet. After cooling, the billet is processed to the required size.

[0183] Example 2

[0184] The process is basically the same as in Example 1, except that in step (1), the raw materials for the chromium oxide refractory are taken according to Table 2, and the first and second synthetic chromium oxide aggregate particles are the corresponding raw materials obtained in Example S2. In step (6), the molding base material is molded in an isostatic press at a pressure of 200 MPa and held for 10 minutes to obtain a green billet. In step (7), the green billet is calcined at 1580°C in a reducing atmosphere and held for 24 hours.

[0185] Example 3

[0186] The process is basically the same as in Example 1, except that the raw materials for the chromium oxide refractory are taken according to Table 2, and the first and second synthetic chromium oxide aggregate particles are the corresponding raw materials obtained in Example S3. In step (6), the molding base material is molded in an isostatic press at a pressure of 240 MPa and held for 8 minutes to obtain a green billet. In step (7), the green billet is calcined at 1610°C in a reducing atmosphere and held for 30 hours.

[0187] Comparative Example 1

[0188] According to the proportions shown in Table 2, chromium oxide green (D50 about 3μm), zircon powder (D50 about 8μm), titanium dioxide (D50 about 2μm), zircon powder (D50 about 5μm), alumina powder (D50 about 5μm) and other raw materials are directly mixed, and 1.5% dextrin and 2% PVA glue are added. After mixing with a wet mill, the mixture is processed according to steps (5)-(7) in Example 1.

[0189] Comparative Example 2

[0190] The commercially available dense chromium oxide brick CR94-HD is produced by Guangzhou Lingnan Refractory Materials Co., Ltd.

[0191] Table 3 Examples and comparative proportions (by weight) of chromium oxide refractory materials

[0192]

[0193] In Table 3, “—” indicates that the component is not added. The weight percentages of the second and third binders are calculated as 100% of the total weight of the first particle, the second particle, the first synthetic chromium oxide aggregate particle, and the second synthetic chromium oxide aggregate particle, because these components are completely decomposed during calcination and are therefore not included in the total weight.

[0194] IV. Performance Test Results

[0195] Performance tests were conducted on the above embodiments and comparative examples, and the results are shown in Tables 4 and 5.

[0196] Table 4 Results of Antioxidant Sublimation Capacity Test

[0197]

[0198] As shown in Table 4, the sublimation rates of Examples 2 and 3 of this application are significantly lower than those of the comparative examples. In particular, the sublimation rate of Example 3 is only 1.97%, which is 36.7% lower than that of Comparative Example 2, demonstrating excellent low sublimation performance. Meanwhile, Example 3 has an apparent porosity as low as 2.0% and a bulk density as high as 4.73 g / cm³. 3 This achieves ultra-high density.

[0199] Figure 1 The images show a comparison of photographs of the sample prepared in Example 3 before and after the antioxidant sublimation test. The comparison shows that the sample surface remained intact after the test, with no obvious peeling, loose layer, or cracks.

[0200] Table 5 Results of glass melt erosion resistance test

[0201]

[0202] As shown in Table 5, the corrosion resistance index (104 / 124) of Example 2 of this application is better than that of Comparative Example 2 (100 / 100) and comparable to that of Comparative Example 1. Although Example 3 is not listed separately, it has a higher density and is expected to have better corrosion resistance. This shows that this application achieves low sublimation without sacrificing glass corrosion resistance.

[0203] Figure 2 Comparative images of photographs taken after glass melt erosion tests on samples prepared in Examples 1, 2, and 2. Figure 2 It can be clearly seen that the samples of Example 1 and Example 2 showed slight erosion at the liquid level line, and their surfaces and cross-sections were smooth and dense, without obvious depressions, holes or cracks. In contrast, the samples of Comparative Example 1 and Comparative Example 2 showed more severe erosion at the liquid level line, and their surfaces and cross-sections had obvious holes and cracks.

[0204] V. Microstructure Characterization

[0205] The samples from Examples 1-3 were observed using a HITACHI scanning electron microscope (SEM). The observation results for the samples from Examples 1-3 are as follows: Figure 3-5As shown in the figure, the SEM images of the embodiments exhibit similar microstructural features, all being an integrated gray matrix with a uniform microporous structure, indicating that the formulation and sintering process of this chromium oxide refractory material have excellent stability and repeatability. The main matrix phase (gray area) has tightly bonded and high-density grains, without large areas of looseness or interconnected macropores, only uniformly distributed small closed pores, indicating that the material is fully sintered and structurally stable, providing a structural basis for excellent mechanical properties and corrosion resistance. The dispersed phase (bright white particles) is uniformly dispersed, without agglomeration or local enrichment, which avoids grain boundary weakening caused by impurity phases, and can also enhance the high-temperature strength and creep resistance of the material through dispersion strengthening, while optimizing thermal shock resistance.

[0206] This application successfully prepared a chromium oxide refractory material with both high erosion resistance and low sublimation rate. Its apparent porosity can be as low as 2.0%, and its bulk density is as high as 4.73 g / cm³. 3 The sublimation rate is reduced by more than 36% compared to commercially available products, while maintaining excellent resistance to glass erosion. Furthermore, the material exhibits stable structure, high density, and good thermal shock resistance. This material is particularly suitable for areas above the liquid level in glass fiber kilns that come into contact with high-moisture atmospheres, and has significant industrial application value.

[0207] The technical features of the above-described embodiments and examples can be combined in any suitable manner. For the sake of brevity, not all possible combinations of the technical features in the above-described embodiments and examples are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0208] The embodiments described above merely illustrate several implementation methods of this application and should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Furthermore, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to this application, and the equivalent forms obtained also fall within the protection scope of this application. It should also be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the protection scope of the appended claims. Therefore, the protection scope of this patent application should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A chromium oxide refractory material, characterized in that, The chromium oxide refractory material comprises, by weight percentage: 91%-92.5% Cr2O3, 2.0%-3.0% ZrO2, 3.5%-4.3% TiO2, 0.8%-1.6% MgO and Al2O3, and unavoidable impurities ≤1%.

2. The chromium oxide refractory material according to claim 1, characterized in that, The chromium oxide refractory material comprises synthetic chromium oxide aggregate particles and a matrix phase filled between the synthetic chromium oxide aggregate particles; The synthetic chromium oxide aggregate particles are pre-synthesized composite solid solutions, whose chemical composition includes Cr2O3, ZrO2, TiO2, MgO and Al2O3; The matrix phase is formed by sintering matrix particles; The matrix particles include a first particle and a second particle; the first particle has a chemical composition of Al2O3; the second particle has a chemical composition of Cr2O3. The first particle is wrapped around the surface of the second particle.

3. The chromium oxide refractory material according to claim 2, characterized in that, The ratio of the particle size of the synthetic chromium oxide aggregate particles to the particle size of the matrix particles is 1.5 to 25. In the matrix particles, the ratio of the particle size D50 of the second particle to that of the first particle is 2 to 12.

4. The chromium oxide refractory material according to claim 3, characterized in that, The synthetic chromium oxide aggregate particles include first synthetic chromium oxide aggregate particles, second synthetic chromium oxide aggregate particles, and third synthetic chromium oxide aggregate particles; The particle size of the first synthetic chromium oxide aggregate particles is d1, where 100μm≤d1<300μm; The particle size of the second synthetic chromium oxide aggregate particles is d2, 50μm≤d2<100μm; The particle size D50 of the third synthetic chromium oxide aggregate particles is d3, 15μm≤d3≤30μm; Optionally, the weight ratio of the first synthetic chromium oxide aggregate particles, the second synthetic chromium oxide aggregate particles, and the third synthetic chromium oxide aggregate particles is (5-20):(5-12):(10-15).

5. The chromium oxide refractory material according to claim 3, characterized in that, The particle size D50 of the first particle is d4, where 1μm≤d4≤3μm; The particle size D50 of the second particle is d5, where 7μm≤d5≤12μm.

6. The chromium oxide refractory material according to any one of claims 2-5, characterized in that, It has one or more of the following characteristics: (1) The synthetic chromium oxide aggregate particles comprise, by weight percentage: Cr2O3 94%-95%, TiO2 3.0%-4.5%, ZrO2 0.5%-1.5%, Al2O3 and MgO sum 0.5%-1.5%, and unavoidable impurities ≤1%; (2) The weight ratio of Al2O3 in the first particle to Cr2O3 in the second particle is (0.05-0.1):1; (3) The chemical composition of the first particle also includes one or more of ZrO2, TiO2 and MgO; (4) The weight ratio of Al2O3, ZrO2, TiO2 and MgO in the first particle is 1:(3-5):(3-5):(0-0.5).

7. The chromium oxide refractory material according to any one of claims 2-5, characterized in that, The aggregate comprises, by weight percentage: 10%-40% of the synthetic chromium oxide aggregate particles, 5%-10% of the first particles, and 50%-80% of the second particles.

8. A method for preparing chromium oxide refractory materials, characterized in that, The chemical composition of the chromium oxide refractory material, by weight percentage, includes: Cr2O3 91%-92.5%, ZrO2 2.0%-3.0%, TiO2 3.5%-4.3%, MgO and Al2O3 sum 0.8%-1.6%, and unavoidable impurities ≤1%; The preparation method includes the following steps: After mixing the first Cr2O3 source powder, the first TiO2 source powder, the first ZrO2 source powder, the first MgO source powder and the first Al2O3 source powder, water and the first binder are added, mixed and ground to obtain aggregate slurry; The aggregate slurry is dried, shaped, pre-fired at 1580℃-1630℃ in a reducing atmosphere, crushed, and sieved to obtain synthetic chromium oxide aggregate particles. The first particles and the second binder are mixed and ground to obtain a first matrix slurry; the first particles include a second Al2O3 source powder. The second particle is added to the first matrix slurry and mixed to obtain the second matrix slurry; the second particle includes the second Cr2O3 source powder. Synthetic chromium oxide aggregate particles and a third binder are added to the second matrix slurry and mixed to obtain molding material slurry; The molding slurry is dried, shaped, and calcined at 1610℃-1630℃ in a reducing atmosphere and kept at that temperature to obtain the chromium oxide refractory material.

9. The preparation method according to claim 8, characterized in that, In the step of preparing the first synthetic chromium oxide aggregate particles, after sieving, synthetic chromium oxide aggregate particles of different particle sizes are obtained, including the first synthetic chromium oxide aggregate particles, the second synthetic chromium oxide aggregate particles and the third synthetic chromium oxide aggregate particles. The particle size of the first synthetic chromium oxide aggregate particles is d1, where 100μm≤d1<300μm; The particle size of the second synthetic chromium oxide aggregate particles is d2, 50μm≤d2<100μm; The particle size D50 of the third synthetic chromium oxide aggregate particles is d3, 15μm≤d3≤30μm; In the step of mixing the synthetic chromium oxide aggregate particles and the third binder into the second matrix slurry, the third synthetic chromium oxide aggregate particles are added first and then mixed, followed by the third binder and then the second synthetic chromium oxide aggregate particles and the first synthetic chromium oxide aggregate particles are added and mixed. Optionally, the third synthetic chromium oxide aggregate particles and the third binder are mixed alternately.

10. The preparation method according to claim 8, characterized in that, One or more of the following conditions must be met: (1) The first adhesive, the second adhesive and the third adhesive each independently comprise one or more of dextrin, sodium carboxymethyl cellulose, silica sol and an aqueous solution of polyvinyl alcohol; (2) The ratio of grinding balls to powder is ≤1.25; (3) The molding method includes isostatic pressing, with a pressure of 200MPa-240MPa and a holding time of 10min-20min; (4) The drying method includes spray drying, and the moisture content of the dried material is ≤0.5%; (5) The heat preservation time is 24h-30h.

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