Mica-based antioxidant coating and method of preparation and use thereof

Abstract

The application belongs to the technical field of inorganic antioxidant coating and discloses a mica-based antioxidant coating, a preparation method and application thereof, aiming at the problem of poor high-temperature antioxidant effect of the existing antioxidant coating of carbon-containing products, wherein the mica-based antioxidant coating is prepared by taking mica powder, borosilicate glass powder and kaolin as raw materials, and the dense gas shielding layer is formed by using the lamellar structure of mica, and the pores between the mica shielding layers are filled with liquid phase by using the borosilicate glass powder at high temperature, so as to form a dense coating, which can stably shield oxygen at high-temperature working conditions, thereby achieving the purpose of high-temperature oxidation resistance, and in addition, the antioxidant coating also has the advantages of excellent acid gas corrosion resistance.

Description

Technical Field

[0001] This invention relates to an inorganic antioxidant coating, specifically to a mica-based antioxidant coating, its preparation method, and its applications, belonging to the technical field of inorganic antioxidant coatings. Background Technology

[0002] Carbon-containing products are widely used as furnace lining bricks in metallurgical furnaces due to their excellent slag resistance and thermal shock resistance. Because metallurgical furnaces require pre-baking at around 1100 degrees Celsius before use, the graphite in the lining bricks oxidizes during this process, forming a 10-30mm decarburized layer. This decarburized layer is loose and porous, making it highly susceptible to erosion and detachment by high-temperature molten steel / slag during use. This shortened effective service length leads to a reduction in the lifespan of the metallurgical furnace. Furthermore, electric arc furnaces in steel plants and mica melting furnaces generally use graphite electrodes for heating. Graphite begins to oxidize at 400 degrees Celsius, and the oxidation rate increases dramatically with rising temperature. Therefore, during high-temperature melting, the graphite at the interface between the melt and air is highly susceptible to rapid oxidation and fracture due to the high temperature and oxidizing atmosphere.

[0003] The above problems can be effectively solved by coating the surface of the target substrate with an antioxidant protective layer. For example, CN1229445C discloses an antioxidant coating for carbon-containing refractory materials: using feldspar powder, pyrophyllite powder, glass, and metal oxides as fillers, modified silicate as a binder, and adding a small amount of performance regulator, a carbon-containing refractory material antioxidant coating that does not require baking is prepared. CN117363071A discloses an antioxidant coating and its preparation method: using glass powder, clay, and flake graphite as fillers, and adding sodium silicate solution, carboxymethyl cellulose, and dextrin, an antioxidant coating for carbon-containing refractory materials is prepared. CN116640513A discloses a prebaked anode high-temperature resistant antioxidant coating for reducing the energy consumption of aluminum electrolytic cells: using potassium feldspar powder, pyrophyllite powder, low-melting-point glass powder, and metal oxides as fillers, phosphate as the main binder, modified glass powder as a pigment, and adding a small amount of performance regulator, a prebaked anode high-temperature resistant antioxidant coating that can reduce the energy consumption of aluminum electrolytic cells is prepared. CN110002839A discloses an antioxidant coating for graphite electrodes used in electric furnace smelting: the antioxidant coating for graphite electrodes in electric furnaces is formulated from raw materials such as silicon carbide powder, dense corundum powder, alumina micro powder, silicon micro powder, metallic silicon powder, boron carbide powder and liquid aluminum dihydrogen phosphate.

[0004] Existing anti-oxidation coatings mostly work by melting the coating to form a liquid film that covers carbon-containing materials, thereby shielding them from oxygen and achieving anti-oxidation. However, the ambient temperature of carbon-containing materials fluctuates greatly. When the ambient temperature rises too much, the viscosity of the low-melting-point materials decreases, and the surface tension increases, causing the liquid film formed by the low-melting-point materials to easily shrink, thus inducing shrinkage cavities and losing its comprehensive protective effect on graphite. At the same time, due to the nature of the raw materials being melted, acidic gases such as fluorides, SO2 / SO3, NOx, and chlorides are always generated during the melting process. These acidic gases further corrode the anti-oxidation coating, weakening its protective effect on the graphite electrode and reducing the coating's service life. Summary of the Invention

[0005] To address the problem of poor high-temperature antioxidant performance of existing antioxidant coatings, this invention provides a mica-based antioxidant coating, its preparation method, and its applications. The mica-based antioxidant coating of this invention is made from mica powder, borosilicate glass powder, kaolin, and other raw materials. The sheet-like structure of mica can form a dense gas shielding layer, giving the antioxidant coating excellent resistance to acidic gas corrosion. Simultaneously, the borosilicate glass powder forms a liquid phase during high-temperature use, filling the pores between the mica shielding layers, thereby forming a dense coating and further shielding against oxygen, thus achieving the purpose of antioxidant properties.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0007] According to a first embodiment of the present invention, a mica-based antioxidant coating is provided:

[0008] A mica-based antioxidant coating comprises a substrate and auxiliary materials, wherein the substrate comprises mica powder, borosilicate glass powder, kaolin, and optionally potassium feldspar. The auxiliary materials comprise a binder, water, and optionally a water-reducing agent and optionally sodium fluorosilicate.

[0009] It should be noted that in this invention, "optional" means "including" or "excluding", or "containing" or "not containing".

[0010] Preferably, the substrate comprises or is composed of the following components: 40-75% mica powder, 15-40% borosilicate glass powder, 1-15% kaolinite, and 0-20% potassium feldspar (total mass percentage 100%).

[0011] Preferably, in the auxiliary materials: the content of the binder is 30-80% of the total mass of the substrate, the content of the water-reducing agent is 0-0.3% of the total mass of the substrate, the content of sodium fluorosilicate is 0-4% of the total mass of the substrate, and the content of water is 50-80% of the total mass of the substrate.

[0012] Preferably, the substrate comprises or is composed of the following components: 53-67% mica powder, 17-27% borosilicate glass powder, 2-10% kaolinite, and 5-17% potassium feldspar (total mass percentage 100%).

[0013] Preferably, in the auxiliary materials: the content of the binder is 35-60% of the total mass of the substrate, the content of the water-reducing agent is 0.05-0.15% of the total mass of the substrate, the content of sodium fluorosilicate is 0.6-3.6% of the total mass of the substrate, and the content of water is 55-75% of the total mass of the substrate.

[0014] Preferably, the mica powder is fluorophlogopite powder, and more preferably, the particle size of the fluorophlogopite powder is D50<20μm and D90<40μm.

[0015] Preferably, the borosilicate glass powder contains 5-40% boron oxide and 5-25% alkali metal oxides, wherein the alkali metal oxides are potassium oxide and / or sodium oxide. Preferably, the particle size of the borosilicate glass powder is 200-400 mesh.

[0016] Preferably, the water-reducing agent is sodium tripolyphosphate and / or sodium hexametaphosphate, with sodium tripolyphosphate being the most preferred.

[0017] Preferably, the binder is one or more of water glass, silica sol, and aluminum silicate, with water glass being the most preferred.

[0018] Preferably, the water is pure water or deionized water, and more preferably deionized water.

[0019] According to a second embodiment of the present invention, a method for preparing a mica-based antioxidant coating is provided:

[0020] A method for preparing a mica-based antioxidant coating, or a method for preparing a mica-based antioxidant coating as described in the first embodiment, the method comprising the following steps:

[0021] 1) First, weigh out mica powder, borosilicate glass powder, kaolin, and optional potassium feldspar as base materials. Then, weigh out binder, water, optional water-reducing agent, and optional sodium fluorosilicate as auxiliary materials.

[0022] 2) First, mix mica powder, borosilicate glass powder, kaolin, potassium feldspar, water-reducing agent and sodium fluorosilicate to obtain a mixed powder. Then, add binder and water to the mixed powder and stir to mix evenly to obtain mica-based antioxidant coating.

[0023] Preferably, in step 1), the mica powder is fluorophlogopite powder, and preferably the particle size of the fluorophlogopite powder is D50<20μm and D90<40μm.

[0024] Preferably, in step 1), the borosilicate glass powder contains 5-40% boron oxide and 5-25% alkali metal oxides, wherein the alkali metal oxides are potassium oxide and / or sodium oxide. Preferably, the particle size of the borosilicate glass powder is 200-400 mesh.

[0025] Preferably, in step 1), the water-reducing agent is sodium tripolyphosphate and / or sodium hexametaphosphate, preferably sodium tripolyphosphate.

[0026] Preferably, in step 1), the binder is one or more of water glass, silica sol, and aluminum silicate, with water glass being the preferred choice.

[0027] Preferably, in step 1), the water is pure water or deionized water, preferably deionized water.

[0028] Preferably, in step 1), the substrate comprises or is composed of the following components: 40-75% mica powder (preferably 53-67% mica powder), 15-40% borosilicate glass powder (preferably 17-27% borosilicate glass powder), 1-15% kaolinite (preferably 2-10% kaolinite), and 0-20% potassium feldspar (preferably 5-17% potassium feldspar).

[0029] Preferably, in step 1), the auxiliary materials contain: 30-80% (preferably 35-60%) of the total mass of the substrate; 0-0.3% (preferably 0.05-0.15%) of the total mass of the substrate; 0-4% (preferably 0.6-3.6%) of the total mass of the substrate; and 50-80% (preferably 55-75%) of the total mass of the substrate.

[0030] According to a third embodiment of the present invention, an application of a mica-based antioxidant coating is provided:

[0031] The use of a mica-based antioxidant coating, or the use of a mica-based antioxidant coating as described in the first embodiment, or the use of a mica-based antioxidant coating prepared by the method described in the second embodiment, involves coating the mica-based antioxidant coating onto the surface of a carbon material or a carbon-containing material as a protective layer. Preferably, the thickness of the protective layer is not less than 0.5 mm, and more preferably 1 to 2 mm.

[0032] In this invention, the mica powder used can be either natural or synthetic mica. However, compared to natural mica, synthetic mica has higher high-temperature resistance, higher hardness, tensile strength, and compressive strength. Therefore, this invention preferably uses synthetic mica with better overall performance and lower impurity content. It should be noted that the synthetic mica powder of this invention is flake-shaped mica powder, which can be used directly as a raw material. Since grinding the synthetic mica powder can significantly reduce the amount of water added, this invention preferably uses ground synthetic mica powder as a raw material (for example, grinding synthetic mica in a ball mill for 0.5-12 hours to achieve a particle size of D50 < 20 μm and D90 < 40 μm). That is, this invention uses flake-shaped mica powder as the base material for the coating, thereby enabling the flake-shaped synthetic mica to interlock and form a dense gas shield layer to isolate oxygen, achieving an antioxidant effect. At the same time, borosilicate glass powder is also used as an auxiliary material. The liquid melt formed by the borosilicate glass powder fills the pores between the mica shielding layers to form a dense coating, which further improves the shielding effect against oxygen and enhances the antioxidant performance.

[0033] In this invention, the borosilicate glass powder contains 5-40% B₂O₃ and 5-25% alkali metal oxides, wherein the alkali metal oxides are potassium oxide and / or sodium oxide. Preferably, the particle size of the borosilicate glass powder is 200-400 mesh.

[0034] In this invention, the mica-based antioxidant coating also contains a certain amount of kaolin. The adhesive properties of kaolin improve the coating's workability and the bond strength between the coating and carbon-containing products, preventing the coating from hardening and peeling off at high temperatures. Furthermore, kaolin itself has high fire resistance (i.e., high temperature resistance), thus it can maintain the bonding strength between other substrates at high temperatures, ensuring the density of the oxygen shielding layer. In addition, when kaolin is heated to near its melting point, it spontaneously fills the intergranular spaces, achieving densification—that is, reaching a state where porosity is essentially at its minimum and density is essentially at its maximum—which further enhances the oxygen shielding effect at high temperatures.

[0035] In this invention, a water-reducing agent is also added to the mica-based antioxidant coating. Adding a certain amount of water-reducing agent can effectively improve the bonding strength and density of the coating after firing. Research has shown that if too much water-reducing agent is added, it will lead to numerous air bubbles in the coating that are difficult to expel. At high temperatures, the bursting of these bubbles will form pores, affecting the coating's antioxidant properties. Conversely, if too little water-reducing agent is added, it will not produce a significant water-reducing effect.

[0036] In this invention, potassium feldspar is selectively added as a high-temperature flux to the mica-based antioxidant coating. Utilizing its softening characteristic at 1050-1100 degrees Celsius, and by combining it with the low-temperature flux borosilicate glass powder, sufficient liquid phase and mica can be generated to form a shielding layer at both medium and high temperatures. Research has shown that if too much potassium feldspar is added, slight graphite oxidation may occur at high temperatures due to the inability to form a dense shielding layer. Conversely, if too little potassium feldspar is added, the coating is prone to forming melt holes at high temperatures due to excessive liquid phase tension.

[0037] In this invention, sodium fluorosilicate is selectively added to the mica-based antioxidant coating as a room-temperature curing agent. This accelerates curing by catalyzing the rapid formation of silica gel via fluoride ions. Research has shown that excessive addition of sodium fluorosilicate leads to overly rapid curing, affecting application; insufficient addition or absence results in slow natural curing. Furthermore, without sodium fluorosilicate, rapid strength can be achieved by direct baking at 100-200 degrees Celsius; therefore, it can be selectively added according to site requirements.

[0038] In this invention, the binder is one or more of water glass, silica sol, and aluminum silicate. The binder provides sufficient bonding strength to the coating at medium and low temperatures to prevent stress cracking at the corners, and also provides a firing aid when used at high temperatures.

[0039] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0040] 1. The mica-based antioxidant coating of the present invention utilizes a combination of mica powder, borosilicate glass powder, kaolin, etc., to achieve the following effects:

[0041] In addition to its excellent high temperature and acid / alkali resistance, the protective coating also has high density, which enables it to effectively and stably isolate oxygen in high temperature fields and has super antioxidant properties.

[0042] 2: This invention further improves the high-temperature resistance of mica-based antioxidant coatings by selectively adding auxiliary materials such as potassium feldspar, sodium tripolyphosphate, and sodium fluorosilicate to the mica-based antioxidant coating. This significantly increases the upper limit of the working temperature of the antioxidant coating, greatly expands the application range of the coating, and enhances its market application potential. Attached Figure Description

[0043] Figure 1 This is a photograph of graphite bricks coated with an antioxidant coating after being treated at 800℃ for 12 hours.

[0044] Figure 2 This is a photograph of the graphite brick of Example 9 of the present invention after being treated at 800°C for 12 hours.

[0045] Figure 3This is a photograph of the graphite brick of Example 1 of the present invention after being treated at 800°C for 12 hours.

[0046] Figure 4 This is a photograph of the graphite brick of Example 12 of the present invention after being treated at 1100°C for 12 hours.

[0047] Figure 5 This is a photograph of the graphite brick of Example 1 of the present invention after being treated at 1100℃ for 12 hours. Detailed Implementation

[0048] The technical solution of the present invention will be illustrated below with examples. The scope of protection sought by the present invention includes, but is not limited to, the following embodiments.

[0049] A mica-based antioxidant coating comprises a substrate and auxiliary materials, wherein the substrate comprises mica powder, borosilicate glass powder, kaolin, and optionally potassium feldspar. The auxiliary materials comprise a binder, water, and optionally a water-reducing agent and optionally sodium fluorosilicate.

[0050] Preferably, the substrate comprises or is composed of the following components: 40-75% mica powder, 15-40% borosilicate glass powder, 1-15% kaolinite, and 0-20% potassium feldspar.

[0051] Preferably, in the auxiliary materials: the content of the binder is 30-80% of the total mass of the substrate, the content of the water-reducing agent is 0-0.3% of the total mass of the substrate, the content of sodium fluorosilicate is 0-4% of the total mass of the substrate, and the content of water is 50-80% of the total mass of the substrate.

[0052] Preferably, the substrate comprises or is composed of the following components: 53-67% mica powder, 17-27% borosilicate glass powder, 2-10% kaolinite, and 5-17% potassium feldspar.

[0053] Preferably, in the auxiliary materials: the content of the binder is 35-60% of the total mass of the substrate, the content of the water-reducing agent is 0.05-0.15% of the total mass of the substrate, the content of sodium fluorosilicate is 0.6-3.6% of the total mass of the substrate, and the content of water is 55-75% of the total mass of the substrate.

[0054] Preferably, the mica powder is fluorophlogopite powder, and more preferably, the particle size of the fluorophlogopite powder is D50<20μm and D90<40μm.

[0055] Preferably, the borosilicate glass powder contains 5-40% boron oxide and 5-25% alkali metal oxides, wherein the alkali metal oxides are potassium oxide and / or sodium oxide. Preferably, the particle size of the borosilicate glass powder is 200-400 mesh.

[0056] Preferably, the water-reducing agent is sodium tripolyphosphate and / or sodium hexametaphosphate, with sodium tripolyphosphate being the most preferred.

[0057] Preferably, the binder is one or more of water glass, silica sol, and aluminum silicate, with water glass being the most preferred.

[0058] Preferably, the water is pure water or deionized water, and more preferably deionized water.

[0059] 1) First, weigh out mica powder, borosilicate glass powder, kaolin, and optional potassium feldspar as base materials. Then, weigh out binder, water, optional water-reducing agent, and optional sodium fluorosilicate as auxiliary materials.

[0060] 2) First, mix mica powder, borosilicate glass powder, kaolin, potassium feldspar, water-reducing agent and sodium fluorosilicate to obtain a mixed powder. Then, add binder and water to the mixed powder and stir to mix evenly to obtain mica-based antioxidant coating.

[0061] Preferably, in step 1), the mica powder is fluorophlogopite powder, and preferably the particle size of the fluorophlogopite powder is D50<20μm and D90<40μm.

[0062] Preferably, in step 1), the borosilicate glass powder contains 5-40% boron oxide and 5-25% alkali metal oxides, wherein the alkali metal oxides are potassium oxide and / or sodium oxide. Preferably, the particle size of the borosilicate glass powder is 200-400 mesh.

[0063] Preferably, in step 1), the water-reducing agent is sodium tripolyphosphate and / or sodium hexametaphosphate, preferably sodium tripolyphosphate.

[0064] Preferably, in step 1), the binder is one or more of water glass, silica sol, and aluminum silicate, with water glass being the preferred choice.

[0065] Preferably, in step 1), the water is pure water or deionized water, preferably deionized water.

[0066] Preferably, in step 1), the substrate comprises or is composed of the following components: 40-75% mica powder (preferably 53-67% mica powder), 15-40% borosilicate glass powder (preferably 17-27% borosilicate glass powder), 1-15% kaolinite (preferably 2-10% kaolinite), and 0-20% potassium feldspar (preferably 5-17% potassium feldspar).

[0067] Preferably, in step 1), the auxiliary materials contain: 30-80% (preferably 35-60%) of the total mass of the substrate; 0-0.3% (preferably 0.05-0.15%) of the total mass of the substrate; 0-4% (preferably 0.6-3.6%) of the total mass of the substrate; and 50-80% (preferably 55-75%) of the total mass of the substrate.

[0068] An application of a mica-based antioxidant coating is described, wherein the mica-based antioxidant coating is applied to the surface of a carbon material or a carbon-containing material as a protective layer. Preferably, the thickness of the protective layer is not less than 0.5 mm, and more preferably 1 to 2 mm.

[0069] Example 1

[0070] Weigh out each substrate separately according to a total mass percentage of 100%, including: 62% synthetic mica powder (D50=14μm, D90=32μm), 20% borosilicate glass powder, 3% kaolin, and 15% potassium feldspar.

[0071] Weigh out each auxiliary material according to the total mass of the substrate, including: 30% water glass solution (Baumé degree 40) based on the total mass of the substrate, 0.1% sodium tripolyphosphate based on the total mass of the substrate, 0.6% sodium fluorosilicate based on the total mass of the substrate, and 70% deionized water based on the total mass of the substrate.

[0072] First, synthetic mica powder, borosilicate glass powder, kaolin, potassium feldspar, sodium tripolyphosphate, and sodium fluorosilicate are mixed to obtain a mixed powder. Then, water glass solution and deionized water are added to the mixed powder and stirred until evenly mixed to obtain a mica-based antioxidant coating.

[0073] The obtained mica-based antioxidant coating was applied to the surface of graphite bricks (10cm×10cm×10cm) using a slurry method (without exposing the graphite base color), forming a coating with an average thickness of approximately 1.5mm. The resulting graphite bricks were then baked at 110℃ for 2 hours to obtain the graphite bricks with the antioxidant coating. The performance of the antioxidant coating was then tested after independently calcining the graphite bricks at 800℃ and 1100℃ for 12 hours.

[0074] Example 2

[0075] Repeat Example 1, except that the amount of potassium feldspar is adjusted from 15% to 20%, while other components and process parameters remain unchanged.

[0076] Example 3

[0077] Repeat Example 1, except that the amount of potassium feldspar is adjusted from 15% to 25%, while other components and process parameters remain unchanged.

[0078] Example 4

[0079] Repeat Example 1, except that the amount of potassium feldspar is adjusted from 15% to 17%, while other components and process parameters remain unchanged.

[0080] Example 5

[0081] Repeat Example 1, except that the amount of potassium feldspar is adjusted from 15% to 10%, while other components and process parameters remain unchanged.

[0082] Example 6

[0083] Repeat Example 1, except that the amount of potassium feldspar is adjusted from 15% to 5%, while other components and process parameters remain unchanged.

[0084] Example 7

[0085] Repeat Example 1, except that the amount of potassium feldspar is changed from 15% to 0%, while other components and process parameters remain unchanged.

[0086] Example 8

[0087] Repeat Example 1, except that the amount of borosilicate glass powder is adjusted from 20% to 17%, while other components and process parameters remain unchanged.

[0088] Example 9

[0089] Repeat Example 1, except that the amount of borosilicate glass powder is adjusted from 20% to 15%, while other components and process parameters remain unchanged.

[0090] Example 10

[0091] Repeat Example 1, except that the amount of borosilicate glass powder is adjusted from 20% to 27%, while other components and process parameters remain unchanged.

[0092] Example 11

[0093] Example 1 was repeated, except that the amount of borosilicate glass powder was adjusted from 20% to 32%, while other components and process parameters remained unchanged.

[0094] Example 12

[0095] Repeat Example 1, except that the amount of borosilicate glass powder is adjusted from 20% to 37%, while other components and process parameters remain unchanged.

[0096] Example 13

[0097] Repeat Example 1, except that the amount of kaolin is adjusted from 3% to 5%, while other components and process parameters remain unchanged.

[0098] Example 14

[0099] Repeat Example 1, except that the amount of kaolin is adjusted from 3% to 10%, while other components and process parameters remain unchanged.

[0100] Example 15

[0101] Repeat Example 1, except that the amount of kaolin is adjusted from 3% to 2%, while other components and process parameters remain unchanged.

[0102] Example 16

[0103] Repeat Example 1, except that the amount of kaolin is adjusted from 3% to 1%, while other components and process parameters remain unchanged.

[0104] Example 17

[0105] Repeat Example 1, except that the amount of kaolin is changed from 3% to 0%, while other components and process parameters remain unchanged.

[0106] Example 18

[0107] Repeat Example 1, except that the amount of synthetic mica powder is adjusted from 62% to 45%, and the amount of deionized water is adjusted from 65% to 47%, while other components and process parameters remain unchanged.

[0108] Example 19

[0109] Repeat Example 1, except that the amount of synthetic mica powder is adjusted from 62% to 53%, and the amount of deionized water is adjusted from 65% to 52%, while other components and process parameters remain unchanged.

[0110] Example 20

[0111] Example 1 was repeated, except that the amount of synthetic mica powder was adjusted from 62% to 58%, and the amount of deionized water was adjusted from 65% to 60%, while other components and process parameters remained unchanged.

[0112] Example 21

[0113] Example 1 was repeated, except that the amount of synthetic mica powder was adjusted from 62% to 67%, and the amount of deionized water was adjusted from 65% to 71%, while other components and process parameters remained unchanged.

[0114] Example 22

[0115] Repeat Example 1, except that the amount of synthetic mica powder is adjusted from 62% to 75%, and the amount of deionized water is adjusted from 65% to 80%, while other components and process parameters remain unchanged.

[0116] Example 23

[0117] Repeat Example 1, except that the amount of sodium tripolyphosphate is adjusted from 0.1% to 0.15%, while other components and process parameters remain unchanged.

[0118] Example 24

[0119] Repeat Example 1, except that the amount of sodium tripolyphosphate is adjusted from 0.1% to 0.3%, while other components and process parameters remain unchanged.

[0120] Example 25

[0121] Repeat Example 1, except that the amount of sodium tripolyphosphate is adjusted from 0.1% to 0.35%, while other components and process parameters remain unchanged.

[0122] Example 26

[0123] Repeat Example 1, except that the amount of sodium tripolyphosphate is adjusted from 0.1% to 0.05%, while other components and process parameters remain unchanged.

[0124] Example 27

[0125] Repeat Example 1, except that the amount of sodium tripolyphosphate is changed from 0.1% to 0%, while other components and process parameters remain unchanged.

[0126] The following table shows a comparison of the states of graphite bricks coated with the anti-oxidation coatings described in each embodiment after heat treatment:

[0127]

[0128]

[0129] As can be seen from Examples 1-12, with the increase of potassium feldspar dosage, the amount of low-temperature melt phase generated gradually decreases under lower temperature conditions. When the amount of melt is too small, the protective shell layer lacks sufficient melt phase and cannot adapt to the expansion and contraction of the matrix, resulting in a certain degree of oxidation of the graphite matrix. Conversely, with the increase of borosilicate glass powder dosage, the amount of high-temperature melt generated gradually increases under high temperature conditions. When the amount of melt is too large, the excessive melt phase film tension makes the mica and other substrates insufficient to resist shrinkage, leading to the formation of melt holes. Furthermore, too many melt holes can merge into sheets, thus losing protection for the graphite matrix and resulting in a greater degree of oxidation of the graphite matrix.

[0130] The reagents used in this invention are sourced from the following sources: the synthetic mica is from Guangxi Qise Pearl Materials Co., Ltd.

[0131] Borosilicate glass powder was purchased from Zhengzhou Hailong Chemical Products Co., Ltd., with a B2O3 content of approximately 18%, sodium oxide content of approximately 7%, and potassium oxide content of <1%. Kaolin was purchased from Gongyi Hengxinda Environmental Protection Technology Co., Ltd. Sodium tripolyphosphate was purchased from Jinhua Shenhua New Materials Co., Ltd. Sodium fluorosilicate was purchased from Shanghai Ruidong Chemical Group Co., Ltd. Potassium feldspar was purchased from Lingshou County Chuanglong Mineral Products Processing Plant. Water glass was purchased from Guangzhou Huayang Chemical Co., Ltd. Graphite bricks were purchased from Qingdao Haibo Carbon Co., Ltd.

Claims

1. A mica-based antioxidant coating, characterized in that: The mica-based antioxidant coating comprises a substrate and auxiliary materials, wherein the substrate includes mica powder, borosilicate glass powder, kaolin, and potassium feldspar; the auxiliary materials include a binder, water, a water-reducing agent, and optionally sodium fluorosilicate. The substrate comprises 53-67% mica powder, 17-27% borosilicate glass powder, 2-5% kaolin, and 10-17% potassium feldspar. In the auxiliary materials, the binder accounts for 30-80% of the total mass of the substrate, the water-reducing agent accounts for 0.05-0.15% of the total mass of the substrate, the sodium fluorosilicate accounts for 0-4% of the total mass of the substrate, and the water content accounts for 50-80% of the total mass of the substrate.

2. The mica-based antioxidant coating according to claim 1, characterized in that: In the auxiliary materials: the content of the binder is 35-60% of the total mass of the substrate, the content of the sodium fluorosilicate is 0.6-3.6% of the total mass of the substrate, and the content of the water is 55-75% of the total mass of the substrate.

3. The mica-based antioxidant coating according to claim 1 or 2, characterized in that: The mica powder is fluorophlogopite powder; and / or The borosilicate glass powder contains 5-40% boron oxide and 5-25% alkali metal oxides, wherein the alkali metal oxides are potassium oxide and / or sodium oxide; and / or The water-reducing agent is sodium tripolyphosphate and / or sodium hexametaphosphate.

4. The mica-based antioxidant coating according to claim 3, characterized in that: The fluorophlogopite powder has a particle size of D50 < 20 μm and D90 < 40 μm; and / or The particle size of the borosilicate glass powder is 200~400 mesh; and / or The water-reducing agent is sodium tripolyphosphate.

5. The mica-based antioxidant coating according to claim 1 or 2, characterized in that: The binder is one or more of water glass, silica sol, and aluminum silicate; and / or The water is pure water or deionized water.

6. The mica-based antioxidant coating according to claim 5, characterized in that: The binder is water glass; and / or The water is deionized water.

7. A method for preparing a mica-based antioxidant coating as described in any one of claims 1-6, characterized in that: The method includes the following steps: 1) First, weigh out mica powder, borosilicate glass powder, kaolin and potassium feldspar as base materials; then weigh out binder, water, water-reducing agent and optional sodium fluorosilicate as auxiliary materials. 2) First, mix mica powder, borosilicate glass powder, kaolin, potassium feldspar, water-reducing agent and sodium fluorosilicate to obtain a mixed powder. Then, add binder and water to the mixed powder and stir to mix evenly to obtain mica-based antioxidant coating.

8. The use of a mica-based antioxidant coating as described in any one of claims 1-6, or the use of a mica-based antioxidant coating prepared by the method described in claim 7, characterized in that: The mica-based antioxidant coating is applied to the surface of carbon materials or carbon-containing materials as a protective layer.

9. The use according to claim 8, characterized in that: The thickness of the protective layer is not less than 0.5 mm.

10. The use according to claim 9, characterized in that: The thickness of the protective layer is 1~2mm.

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