Reduction-erosion-resistant corundum coating as well as preparation method and application thereof

Abstract

The invention relates to a reduction-erosion-resistant corundum coating as well as a preparation method and application thereof, and belongs to the field of unshaped refractory materials. The coating comprises 5-10 parts of activated aluminum oxide micro powder, 30-40 parts of white corundum, 5-10 parts of potassium feldspar, 5-10 parts of bentonite, 3-5 parts of silicon dioxide micro powder recycled from an electric furnace, 1-5 parts of boric acid, 30-50 parts of aluminum dihydrogen phosphate and 5-10 parts of aluminum sol. The preparation method comprises the steps of dry mixing, binding agent adding, aluminum sol solution introducing, stirring and the like. The compact coating is formed through a multi-scale particle close packing and synergistic bonding mechanism, and the compactness, the normal-temperature strength and the high-temperature stability of the coating are remarkably improved. When the coating is coated on the surface of an aluminum-silicon refractory material, the corrosion of CO and H2 can be effectively blocked, the service life of linings of devices such as a hydrogen-based shaft furnace is greatly prolonged, and the coating has excellent corrosion resistance and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of unshaped refractory materials, and more specifically, to a corundum coating for resisting CO and H2 corrosion in reducing atmosphere industrial kilns such as hydrogen-based vertical shaft furnaces, its preparation method, and its application. Background Technology

[0002] Hydrogen-based vertical shaft furnace technology is one of the important directions for the green transformation of the steel industry. Unlike traditional blast furnace ironmaking, which relies on the combustion of coke to produce CO as a reducing agent and emits a large amount of CO2, hydrogen-based vertical shaft furnaces use hydrogen as a reducing agent, and its reduction product is water, thus achieving zero carbon emission requirements.

[0003] However, the service environment of hydrogen-based shaft furnaces places extremely stringent requirements on refractory linings. Traditionally widely used alumina-silicon based refractory materials (such as high-alumina bricks and mullite bricks) exhibit serious defects in this environment: these materials have a high Fe2O3 content, which is easily reduced to elemental iron in a hydrogen atmosphere, leading to irreversible changes in material volume and a significant decrease in mechanical properties (such as compressive strength); at the same time, they have a high SiO2 content, which is extremely unstable in a high-temperature hydrogen environment. SiO2 undergoes a reduction reaction in a high-temperature hydrogen environment, generating gaseous SiO and H2O. The gaseous SiO escapes, which not only causes the loss of material components but also leaves pores in the matrix, damaging its microstructure and significantly reducing its service life.

[0004] Although some existing corundum materials have better chemical inertness and reduction resistance than traditional aluminum-silicon materials, they still have problems such as weak anti-penetration ability, easy cracking of coatings, and weak bonding with the substrate under the high pressure H2 / CO synergistic erosion environment of hydrogen-based vertical furnaces. As a result, the service life of the materials is far from meeting the needs of industrial production, requiring frequent replacement, increasing production costs and affecting production continuity.

[0005] In summary, the existing technology lacks a coating that can effectively isolate aluminosilicate refractory materials from reducing atmospheres, while also possessing high compressive strength, strong resistance to H2 / CO erosion, and excellent adhesion. Therefore, the development of such a coating has become a key requirement for the large-scale application of hydrogen-based vertical shaft furnace technology. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide an anti-reduction corrosion corundum coating, its preparation method and application. The coating is designed to form a dense and strong physicochemical barrier, effectively blocking the penetration and reaction of H2 and CO molecules to the underlying refractory material, while possessing high compressive strength, excellent adhesion and high temperature stability.

[0007] To achieve the above objectives, the specific solution adopted by the present invention is as follows: In a first aspect, the present invention provides an anti-reduction erosion corundum coating comprising the following raw materials in parts by weight: 5-10 parts of activated alumina micro powder, 30-40 parts of white corundum, 5-10 parts of potassium feldspar, 5-10 parts of bentonite, 3-5 parts of electric furnace recycled silica micro powder, 1-5 parts of boric acid, 30-50 parts of aluminum dihydrogen phosphate, and 5-10 parts of aluminum sol.

[0008] Furthermore, the raw material ratio of the coating is as follows: 10 parts activated alumina micro powder, 30 parts white corundum, 7 parts potassium feldspar, 5 parts bentonite, 3 parts recycled silica micro powder from electric furnace, 1 part boric acid, 34 parts aluminum dihydrogen phosphate, and 10 parts aluminum sol.

[0009] Furthermore, the particle size requirements for each raw material are as follows: the particle size of activated alumina micro powder is 3-6 μm; the particle size of white corundum is less than 0.075 mm; the particle size of potassium feldspar is less than 0.088 mm; the particle size of bentonite is less than 0.075 mm; and the particle size of silicon dioxide micro powder recovered from electric furnace is less than 5 μm.

[0010] Furthermore, the chemical purity requirements for each raw material are as follows: the mass fraction of Al2O3 in the activated alumina micro powder is ≥99.5%, the mass fraction of Al2O3 in the white corundum is ≥30%, the mass fraction of K2O in the potassium feldspar is ≥15%, the mass fraction of Al2O3 in the bentonite is ≥33%, and the mass fraction of SiO2 in the silicon micro powder is ≥98.5%.

[0011] Secondly, the present invention provides a method for preparing the above-mentioned anti-reduction erosion corundum coating, comprising the following steps: (1) Weigh each raw material according to the above-mentioned mass proportions; (2) Weigh the activated alumina micro powder, white corundum, potassium feldspar, bentonite and electric furnace recovered silica micro powder from step (1) and put them into a mixing device and stir for 1-2 minutes. (3) Add boric acid and aluminum dihydrogen phosphate to the stirring equipment and stir for 1-2 minutes; (4) Dissolve aluminum sol in water, add it to a stirring device, and stir for 2-3 minutes to obtain a paste-like anti-reduction corrosion corundum coating.

[0012] Furthermore, in step (4), the amount of water added to dissolve the aluminum sol is 20%-40% of the total weight of the raw materials.

[0013] Thirdly, the present invention provides the application of the above-mentioned anti-reduction corrosion corundum coating in protecting aluminosilicate refractory materials from CO and H2 corrosion.

[0014] Furthermore, the coating and curing process of the coating includes the following steps: a) Immerse the aluminum-silicon refractory material in the anti-reduction corrosion corundum coating for 1-2 minutes; b) Remove the impregnated refractory material and allow it to dry under natural conditions for 24 hours; c) Heat-treat the dried refractory material at 300℃ for 8 hours.

[0015] The functions of each ingredient: (1) Activated alumina micro powder: It has a high specific surface area and high reactivity, which can fill the pores in the coating, improve the density, and react with the phosphoric acid system to enhance the overall structure.

[0016] (2) White corundum: As the main aggregate, it provides high-temperature stability, wear resistance and skeleton support for the coating.

[0017] (3) Potassium feldspar: It forms a liquid phase at high temperature, which strengthens the grain boundary and reduces the penetration of H2.

[0018] (4) Bentonite: It has good dispersibility and adhesion, can form a physical barrier in the coating, greatly prolong the gas penetration path, significantly reduce the permeability, and can temporarily fix CO molecules and delay their migration.

[0019] (5) Recycled silica micro powder in electric furnace: Its particle size is extremely small, which can fill the gaps between larger particles, enhancing the fluidity of the coating material and the bonding strength during coating.

[0020] (6) Boric acid: Used as a binder, it can improve the strength of the coating and resist acid corrosion. At high temperatures, it can form a borate glass phase with oxides, which acts as a flux and sealant, further improving the density of the coating. The addition of low-melting-point substances ensures high-temperature performance.

[0021] (7) Aluminum dihydrogen phosphate: As the main inorganic binder, it can be cured at low temperature (about 300°C) to form a ceramic bond, avoiding abnormal grain growth caused by high-temperature sintering. At high temperatures, it can react with the substrate and filler to form a hard aluminum phosphate ceramic layer, providing extremely high bonding strength and heat resistance.

[0022] (8) Aluminum sol: As a nano-binder and reinforcing phase, its nanoparticles can fill the gaps in the aluminum dihydrogen phosphate network and significantly improve the density, hardness, heat resistance and bonding strength of the coating film by forming -Al-OP- chemical bonds, indirectly but very effectively enhancing the barrier properties and durability against H2 and CO.

[0023] Beneficial effects: Compared with the prior art, the anti-reduction erosion corundum coating and its preparation method provided by the present invention have the following significant advantages: (1) In this invention, aluminum dihydrogen phosphate can form a ceramic bond at 300℃, avoiding abnormal grain growth caused by high-temperature sintering. As the main inorganic binder, it can react with the substrate and filler at high temperature to generate a hard aluminum phosphate ceramic layer, providing extremely high bonding strength and heat resistance. Aluminum sol, as a nano-binder and reinforcing phase, has nanoparticles that can fill the voids in the aluminum dihydrogen phosphate network and significantly enhance the density, toughness, and initial adhesion of the coating by forming "-Al-OP-" bonds, preventing the brittleness that may occur in the pure phosphate system. The combination of the two forms a "rigid and flexible" inorganic bonding network, which maintains the high-temperature resistance of phosphate while compensating for its brittleness, ensuring the integrity, impact resistance, and crack resistance of the coating.

[0024] (2) The activated alumina micro powder in this invention has a high specific surface area and high reactivity, which can adsorb gases and further react with the phosphoric acid system to enhance the overall structure; its particle size is 3-6 μm, which can fill the gaps between dry materials such as white corundum and potassium feldspar, and improve the density of the coating. The particle size of the silicon dioxide micro powder recovered by the electric furnace is less than 5 μm (nano to submicron level), which can further fill the tiny pores between the activated alumina micro powder and other dry materials - the two form the "micron + nano" most compact packing structure, which almost blocks all micropores and channels of the coating, greatly increases the tortuosity of the diffusion path of H2 and CO molecules, forms a physical barrier layer, and reduces gas permeation.

[0025] (3) In this invention, boric acid can form a borate glass phase with oxides at high temperatures, which acts as a flux and sealant, further improving the density and gloss of the coating; and its addition does not introduce low-melting-point substances, ensuring high-temperature performance. Potassium feldspar can achieve grain boundary strengthening and reduce H2 penetration; under high-temperature conditions, the molten glass phase of boric acid and potassium feldspar will flow, healing microcracks caused by organic matter decomposition or thermal stress, and together with the unmelted white corundum, activated alumina and other skeletons, it forms a continuous, dense and strong ceramic-glass composite barrier, further blocking CO and H2 erosion.

[0026] (4) According to the test results of the present invention, the coating of the present invention can significantly reduce the apparent porosity of the substrate (from ≥19.9% ​​to ≤16.5%), impart high room temperature compressive strength (≥92MPa) to the coating, and exhibit extremely low mass loss rate and extremely high strength retention rate in high temperature CO and H2 environments, with excellent anti-carbon deposition performance. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0028] In a first aspect, the present invention provides an anti-reduction erosion corundum coating comprising the following raw materials in parts by weight: 5-10 parts of activated alumina micro powder, 30-40 parts of white corundum, 5-10 parts of potassium feldspar, 5-10 parts of bentonite, 3-5 parts of electric furnace recycled silica micro powder, 1-5 parts of boric acid, 30-50 parts of aluminum dihydrogen phosphate, and 5-10 parts of aluminum sol.

[0029] The particle size requirements for each raw material are as follows: activated alumina micropowder with a particle size of 3-6 μm; white fused alumina with a particle size of less than 0.075 mm; potassium feldspar with a particle size of less than 0.088 mm; bentonite with a particle size of less than 0.075 mm; and electric furnace recycled silica micropowder with a particle size of less than 5 μm. White fused alumina, as the main aggregate, with a particle size (<0.075 mm, i.e., above 200 mesh), constitutes the macroscopic framework of the coating. Activated alumina micropowder (3-6 μm) acts as a micron-level filler, filling the voids between the white fused alumina framework particles. Electric furnace recycled silica micropowder (<5 μm, especially the nano-sized particles) acts as a submicron or even nano-level filler, further filling even finer pores. This "coarse-medium-fine" particle size distribution achieves the densest packing, greatly reducing interconnected pores within the coating, increasing the tortuosity of the diffusion paths of H2 and CO gas molecules, and forming an effective physical barrier layer. The fine particle size of potassium feldspar and bentonite (<0.088 mm and <0.075 mm, respectively) ensures their uniform dispersion in the system, allowing them to quickly exert their effects of forming a liquid phase (potassium feldspar) and providing physical thickening and barrier properties (bentonite) at high temperatures. The fine particles have a larger specific surface area, enabling more thorough contact and reaction with the binders (aluminum dihydrogen phosphate, aluminum sol), thereby improving the coating's room-temperature compressive strength and bonding strength.

[0030] It should be noted that the chemical purity requirements for each raw material are as follows: the mass fraction of Al2O3 in the activated alumina micropowder is ≥99.5%, the mass fraction of Al2O3 in the white corundum is ≥30%, the mass fraction of K2O in the potassium feldspar is ≥15%, the mass fraction of Al2O3 in the bentonite is ≥33%, and the mass fraction of SiO2 in the silica micropowder is ≥98.5%. The high purity of the activated alumina micropowder (Al2O3 ≥99.5%) and silica micropowder (SiO2 ≥98.5%) means that the content of introduced impurities (such as Fe2O3, Na2O, K2O, etc.) is extremely low. These impurities are usually low-melting-point substances or components that are easily reduced in an H2 / CO environment. High purity ensures the chemical inertness and high-temperature volume stability of the coating's main framework under a reducing atmosphere from the source. This is directly related to excellent anti-carbon deposition performance and extremely low mass loss rate. Potassium feldspar contains at least 15% K₂O. Specifying a lower limit for K₂O content ensures sufficient formation of an effective liquid phase at high temperatures, thereby strengthening grain boundaries and sealing microcracks. Insufficient K₂O content weakens this function. Similarly, the Al₂O₃ content in white fused alumina and bentonite is limited to ensure the correctness of their phase composition and functionality. White fused alumina requires a sufficient corundum phase to provide a framework, while bentonite needs to maintain its predominant aluminosilicate structure to achieve good dispersibility and adhesion.

[0031] Secondly, the present invention provides a method for preparing the above-mentioned anti-reduction erosion corundum coating, comprising the following steps: Step (1): Accurately weigh the raw materials: According to the above formula, weigh the activated alumina micro powder, white corundum, potassium feldspar, bentonite, and electric furnace recycled silica micro powder (dry components), as well as boric acid, aluminum dihydrogen phosphate, and aluminum sol (functional components), to ensure that the quality error of each raw material is ≤ ±0.1 parts, and to ensure the stability of the subsequent coating performance. Step (2): Preliminary mixing of dry materials: Place the dry materials (activated alumina micro powder, white corundum, potassium feldspar, bentonite, and electric furnace recycled silica micro powder) weighed in step (1) into a mixing device and stir for 1-2 minutes. The purpose is to make the dry material components evenly dispersed, avoid the agglomeration of single dry materials, and lay the mixing foundation for the subsequent addition of functional components; Step (3): Add binder components: Add boric acid and aluminum dihydrogen phosphate (two key binders) to the dry mixture from step (2) and continue stirring for 1-2 minutes. The core of this step is to ensure that the binder and the dry mixture are in full contact, initially forming a "dry mixture-binder" premixed system, which prepares for the subsequent formation of the bonding network; Step (4): Add aluminum sol aqueous solution to form coating: Dissolve aluminum sol in an appropriate amount of added water, stir evenly, and then add it to the premixed system in step (3). Continue stirring for 2-3 minutes until the system forms a uniform paste, thus obtaining a corundum coating resistant to CO and H2 corrosion. In this step, aluminum sol is easier to disperse after dissolving in water, avoiding uneven dispersion caused by directly adding solid aluminum sol. The longer stirring time of 2-3 minutes allows the aluminum sol to fully fill the gaps in the aluminum dihydrogen phosphate network, forming "-Al-OP-" bonds, ensuring the integrity of the bonding network. Finally, a uniform paste coating is formed, ensuring the fluidity and adhesion during coating (such as immersion in the substrate), and avoiding bubbles and pinholes in the coating.

[0032] Thirdly, the present invention provides the application of the above-mentioned anti-reduction corrosion corundum coating in protecting aluminosilicate refractory materials from CO and H2 corrosion.

[0033] Furthermore, the coating and curing process of the coating includes the following steps: a) The aluminosilicate refractory material is immersed in the anti-reduction corrosion corundum coating for 1-2 minutes. This step aims to form a complete, uniform and well-adhered initial wet film on the surface of the refractory material through immersion. The 1-2 minute immersion time ensures that the coating slurry can fully penetrate into the micropores on the surface of the substrate and achieve the required coating thickness, laying the foundation for subsequent drying and curing. b) Remove the impregnated refractory material and allow it to dry under natural conditions for 24 hours. This step is the preparation stage for coating curing. Slow drying under natural conditions for 24 hours allows the moisture in the coating to evaporate evenly and slowly. This avoids defects such as cracking and peeling caused by rapid evaporation of moisture. On the other hand, it helps the colloidal particles (such as aluminum sol) and binders (such as aluminum dihydrogen phosphate) in the coating to achieve initial coagulation and adhesion, forming a gel structure with a certain initial strength, ensuring the integrity of the coating before entering high-temperature treatment. c) The dried refractory material is heat-treated at 300℃ for 8 hours. The purpose of this step is: First, to thoroughly remove residual moisture and water of crystallization, preventing their rapid vaporization at higher temperatures from damaging the coating. Second, to promote the ceramization reaction of the main binder, aluminum dihydrogen phosphate, forming a robust aluminum phosphate ceramic bonding phase, endowing the coating with high bonding strength, heat resistance, and structural stability. Third, to further dehydrate and condense alumina sol and other nanoparticles, forming a stable inorganic network that fills and strengthens the phosphate skeleton, jointly constructing a dense, complete, and flexible inorganic protective layer. Fourth, this heat treatment process ensures that the coating completely transforms from a physically adsorbed wet film into a chemically bonded dense ceramic barrier, thereby giving it excellent resistance to CO and H2 corrosion.

[0034] The technical solution of the present invention will be further described below with reference to specific embodiments and comparative examples.

[0035] Example 1 The anti-reduction erosion corundum coating of this embodiment is prepared according to the following steps: (1) Weighing: Weigh 10 parts of activated alumina micro powder with a particle size of 3-6μm, 30 parts of white corundum with a particle size of less than 0.075mm, 7 parts of potassium feldspar with a particle size of less than 0.088mm, 5 parts of bentonite with a particle size of less than 0.075mm, 3 parts of electric furnace recovered silica micro powder with a particle size of less than 5μm, 1 part of boric acid, 34 parts of aluminum dihydrogen phosphate, and 10 parts of aluminum sol; add water at 40% of the total weight of the above raw materials; (2) Put the dry materials (activated alumina micro powder, white corundum, potassium feldspar, bentonite, silica micro powder) into the mixing equipment and stir for 2 minutes; (3) Add 1 part boric acid and 34 parts aluminum dihydrogen phosphate, and continue stirring for 2 minutes; (4) Dissolve 10 parts of aluminum sol in an appropriate amount of added water, add it to the above system and stir for 3 minutes to obtain the coating.

[0036] Immerse the aluminum-silicon refractory material in the coating for 1 minute (to ensure uniform coating adhesion), let it air dry for 24 hours, and then place it in a kiln at 300℃ for 8 hours (to allow aluminum dihydrogen phosphate to form a ceramic bond), and then test it.

[0037] Comparative Example 1 (without boric acid) The difference between this comparative example and Example 1 is that boric acid is not added, while 35 parts of aluminum dihydrogen phosphate are added.

[0038] Comparative Example 2 (without aluminum sol) The difference between this comparative example and Example 1 is that aluminum sol is not added, while 45 parts of aluminum dihydrogen phosphate are added.

[0039] Comparative Example 3 (without coating) The difference between this comparative example and Example 1 is that the ordinary aluminosilicate refractory material used in Example 1 is not coated in any way.

[0040] The products obtained in Example 1 and Comparative Examples 1-3 were subjected to performance tests, and the laboratory test indicators are shown in Table 1. The standards used for testing were as follows: chemical analysis according to GB / T 6900, refractoriness according to GB / T 7322, room temperature flexural strength according to GB / T 3001, room temperature compressive strength according to GB / T 5072, permanent linear change upon heating according to GB / T 5988, and the sample preparation method for acid-resistant coating material according to YB / T 5202.1. The test results are shown in Table 1.

[0041] Table 1 Performance test results of the products obtained in Example 1 and Comparative Examples 1-3 Analysis of the data in Table 1 shows that, compared to Comparative Examples 1-3, the apparent porosity of the CO and H2 erosion-resistant corundum coating prepared in Example 1 after immersion is ≤13.9%, its room temperature compressive strength is ≥92 MPa, its carbon deposition resistance rate (200h in a CO environment at 850℃) is ≤1%, its compressive strength retention rate (100h in a H2 environment at 500℃) is ≥92%, its mass loss rate (100h in a CO environment at 500℃) is ≤1.5%, and its mass loss rate (100h in a H2 environment at 500℃) is ≤2.0%. This indicates that the complete formulation of Example 1 of the present invention exhibits optimal overall performance. Compared to the uncoated Comparative Example 3, Example 1 significantly reduces apparent porosity, improves room temperature compressive strength, and exhibits optimal anti-carbon deposition performance and the lowest mass loss rate in both CO and H2 environments. Compared to Comparative Example 1 without boric acid, the superior strength and corrosion resistance of Example 1 confirm the crucial role of boric acid in forming a high-temperature glass phase. Furthermore, compared to Comparative Example 2 without aluminum sol, the lower apparent porosity and higher strength retention of Example 1 highlight the irreplaceable role of aluminum sol in enhancing coating density and adhesion strength. These comparisons fully validate the synergistic effect of the components in the formulation of this invention.

[0042] In summary, this invention, through unique raw material ratios and synergistic effects, successfully prepared a corundum coating with extremely high resistance to CO and H2 erosion, high strength, and good workability. It can effectively protect the refractory lining in hydrogen-based vertical shaft furnaces and significantly extend their service life.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A corundum coating resistant to reduction corrosion, characterized in that, The raw materials contain the following parts by weight: 5-10 parts activated alumina micro powder, 30-40 parts white corundum, 5-10 parts potassium feldspar, 5-10 parts bentonite, 3-5 parts recycled silica micro powder from electric furnace, 1-5 parts boric acid, 30-50 parts aluminum dihydrogen phosphate, and 5-10 parts aluminum sol.

2. The anti-reduction corrosion corundum coating as described in claim 1, characterized in that, The raw materials contain the following parts by weight: 10 parts activated alumina micro powder, 30 parts white corundum, 7 parts potassium feldspar, 5 parts bentonite, 3 parts recycled silica micro powder from electric furnace, 1 part boric acid, 34 parts aluminum dihydrogen phosphate, and 10 parts aluminum sol.

3. The anti-reduction corrosion corundum coating as described in claim 1, characterized in that, The particle size of the activated alumina micro powder is 3-6 μm; The white corundum has a particle size of less than 0.075 mm; The potassium feldspar has a particle size of less than 0.088 mm; The bentonite has a particle size of less than 0.075 mm; The particle size of the silica micropowder recovered by the electric furnace is less than 5 μm.

4. The anti-reduction corrosion corundum coating as described in claim 1, characterized in that, The activated alumina micro powder has an Al2O3 mass fraction ≥99.5%, the white corundum has an Al2O3 mass fraction ≥30%, the potassium feldspar has a K2O mass fraction ≥15%, the bentonite has an Al2O3 mass fraction ≥33%, and the electric furnace recycled silica micro powder has a SiO2 mass fraction ≥98.5%.

5. A method for preparing an anti-reduction-erosion corundum coating as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Weigh each raw material according to the mass fractions specified in claim 1; (2) Weigh the activated alumina micro powder, white corundum, potassium feldspar, bentonite and electric furnace recovered silica micro powder from step (1) and put them into a mixing device and stir for 1-2 minutes. (3) Add boric acid and aluminum dihydrogen phosphate to the stirring equipment and stir for 1-2 minutes; (4) Dissolve aluminum sol in water, add it to a stirring device, and stir for 2-3 minutes to obtain a paste-like anti-reduction corrosion corundum coating.

6. The method for preparing a corundum coating resistant to reduction corrosion as described in claim 5, characterized in that, In step (4), the amount of water added to dissolve the aluminum sol is 20%-40% of the total weight of the raw materials.

7. The application of the anti-reduction corrosion corundum coating as described in any one of claims 1-4 in protecting aluminosilicate refractory materials from CO and H2 corrosion.

8. The application as described in claim 7, characterized in that, The coating and curing process of the coating includes the following steps: a) Immerse the aluminum-silicon refractory material in the anti-reduction corrosion corundum coating for 1-2 minutes; b) Remove the impregnated refractory material and allow it to dry under natural conditions for 24 hours; c) Heat-treat the dried refractory material at 300℃ for 8 hours.

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