Preparation method of high-temperature-resistant anti-oxidation coating

Abstract

The invention discloses a preparation method of a high-temperature-resistant antioxidant coating, which comprises the following steps: step 1, weighing the following raw materials in percentage by mass: 50-70% of oxide ceramic powder, 20-40% of inorganic binder, 5-20% of joint mixture, 5-20% of amorphous substance, 0-5% of defoaming agent and 0-5% of dispersing agent; 2, the weighed powder is put into a dry roller to be overturned and mixed, the rotating speed of the roller is 30 revolutions per minute, and mixing is conducted for 2 hours; 3, taking out the dry-mixed powder, adding water, stirring, adding 30 parts of water into every 100 parts of dry powder, and uniformly stirring to form white slurry; step 4, standing the uniformly stirred slurry for 2 hours, wherein no obvious precipitate is generated after standing; step 5, uniformly coating the slurry after standing on the surface of the material; sixthly, the coated material is placed at the room temperature to be dried for 30 minutes; and step 7, sintering the dried material in a high-temperature atmospheric environment.

Description

Technical Field

[0001] The present invention relates to the field of high temperature resistant and anti-oxidation coatings, and in particular to a preparation method of high temperature resistant and anti-oxidation coatings. Background Art

[0002] Graphite, with its excellent heat resistance, corrosion resistance, and electrical conductivity, is widely used in modern industrial equipment. In the metallurgical, atomic, and aerospace industries, graphite is widely used as electrodes, electrolytic anodes, casting molds, and high-temperature seals. However, during high-temperature operation, graphite is susceptible to oxidation, which affects its electrical and mechanical properties. Graphite oxidation begins at 450°C and rapidly increases above 750°C, with the oxidation rate increasing with increasing temperature. Therefore, applying an oxide coating to the outer surface of graphite can significantly reduce the oxidation rate and extend its service life. In addition to graphite, metal materials connected to graphite are also subject to long-term high-temperature operation. At these temperatures, metals rapidly oxidize, forming an oxide layer. When this oxide layer falls off, new surfaces are exposed to further oxidation. This repetitive oxidation and shedding cycle accelerates the consumption of the metal and affects its conductivity. To ensure long-term operation in high-temperature environments, an anti-oxidation coating is applied to the surface of the material. The coating has the following characteristics: 1) High-temperature stability. Within the service temperature range of the carbon-based material, the coating material has high stability and does not undergo phase change or other rapid volume expansion or contraction. 2) Chemical inertness. During long-term service at high temperatures, the coating material must have high chemical stability requirements and must not react with oxygen or nitrogen in the air. 3) Density. At high temperatures, the coating can greatly slow down the growth of oxygen atoms penetrating the coating, allowing the interior of the carbon-based material to be in an oxygen-free environment for a long time, reducing the probability of carbon oxidation reactions. 4) Convenient construction. As a coating material that can be used for large-scale industrial applications, it must be simple to operate, easy to construct, and not dependent on large and complex equipment. 5) Low price. Low cost is the most important condition for large-scale commercial use of coatings.

[0003] Existing antioxidant coating technologies are strictly targeted, with most being designed for graphite materials. There are no coatings that can protect both graphite and metal surfaces. These technologies primarily employ ceramics, metal powders, and glass as protective coating materials. Patent CN202211127112.4 uses CaO, SiO2, MgO, Al2O3, TiO2, and TiC metal oxides and carbides as raw materials for antioxidant coatings for graphite electrodes. However, without a binder or caulk, pores still exist between the particles, resulting in poor high-temperature oxidation resistance. Patent CN201410842455.8 relates to a conductive, antioxidant, self-healing graphite electrode coating that utilizes metal powder as a principle and is relatively expensive. Patent CN200710052122.5 describes an antioxidant coating for graphite electrodes and its preparation process, using boric acid, water, glass, and silica as raw materials. While offering good oxidation resistance, the maximum operating temperature is limited to 850°C. At higher temperatures, the viscosity of the glass oxide layer decreases, making the coating susceptible to breakage. Summary of the Invention

[0004] The main purpose of the present invention is to propose a method for preparing a high-temperature resistant and antioxidant coating, aiming to solve the problem of preparing a graphite / metal integrated antioxidant coating under high temperature conditions and provide a method for preparing a high-temperature resistant and antioxidant coating.

[0005] To achieve the above object, the present invention proposes a method for preparing a high-temperature resistant and oxidation-resistant coating, comprising the following steps:

[0006] Step 1: weigh the raw materials according to the mass ratio, 50-70% of oxide ceramic powder, 20-40% of inorganic binder, 5-20% of caulking agent, 5%-20% of amorphous material, 0-5% of defoaming agent, and 0-5% of dispersant;

[0007] Step 2: Place the weighed powder into a dry drum for mixing at a speed of 30 rpm for 2 hours.

[0008] Step 3: Take out the mixed dry powder and add water to stir, adding 30 parts of water for every 100 parts of dry powder, and stir evenly to form a white slurry;

[0009] Step 4: After the evenly stirred slurry is allowed to stand for 2 hours, no obvious precipitation is observed;

[0010] Step 5: Evenly apply the slurry after standing on the surface of the material;

[0011] Step 6: Place the coated material at room temperature to dry for 30 minutes;

[0012] Step seven: placing the dried material in a high-temperature atmospheric environment for sintering.

[0013] Optionally, the order of placing the raw materials in step 1 is: first place the oxide ceramic material, then place the inorganic binder, and finally mix the filler, amorphous substance, defoamer and dispersant together and pour them into the mixture of oxide ceramic material and inorganic binder.

[0014] Optionally, the oxide ceramic powder includes bauxite and silicon dioxide.

[0015] Optionally, the inorganic binder includes sodium pyrophosphate and sodium hexametaphosphate.

[0016] Optionally, the amorphous substance is mainly amorphous silicon oxide and amorphous zirconium oxide.

[0017] Optionally, the defoaming agent is polyether-modified silicone oil.

[0018] Optionally, the dispersant is polyethylene glycol.

[0019] Optionally, the filler is made of nano-scale zircon.

[0020] Optionally, the diameter of the dry drum is 400 mm, and the volume of the powder in the dry mixing barrel described in step 2 does not exceed 30% of the volume of the barrel.

[0021] Optionally, during the process of adding water and stirring in step 3, 30% water is first added and stirred evenly to form a viscous solution, and then water is continuously added to dilute it until a uniform slurry coating is formed.

[0022] Optionally, the container needs to be covered and sealed during the standing process in step 4 to prevent water evaporation and loss. During the standing process, the oxide ceramic powder and other additives gradually diffuse in the water, the surface is completely wetted, the dispersant is evenly distributed between the particles and neutralizes the charge on the surface of the ceramic particles, forming a completely uniform solution without agglomeration and precipitation;

[0023] In step five, when the material is graphite, the slurry after standing is poured directly onto the graphite surface, and the slurry is flattened and formed by itself under the action of gravity; when the material is metal, the metal surface is first shot blasted to remove rust, and then the slurry is sprayed on the surface of the metal material using a compressed air spray gun.

[0024] Optionally, in step six, the formed anti-oxidation coating is dried at room temperature for 30 minutes, and the thickness of the film layer after drying is 20-30 microns.

[0025] Optionally, in step seven, the dried coating is directly sintered in a high-temperature working area at a temperature of 500-1000 degrees Celsius.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention uses oxide ceramic powder, inorganic binder, caulking agent, and amorphous material as the main raw materials, and adopts traditional ceramic powder as the main aggregate and antioxidant, which can not only ensure high-temperature oxidation resistance but also significantly reduce costs. The inorganic binder can achieve room temperature bonding, ensuring the bond strength after coating. The caulking agent can further fill the pores formed by the ceramic aggregate, further improving the oxidation resistance of the coating. The glassy material forms a viscous substance at high temperature, filling the gaps between the glassy material and the pores, completely isolating the air from the matrix material, and achieving a high-temperature oxidation resistance effect.

[0028] 2. Compared with traditional materials such as boric acid and glass, the present invention has a lower glass content, and the main sealing role is played by the filler. The fine filler is filled between the ceramic aggregate particles to form a closed insulating layer, which greatly improves the high-temperature oxidation resistance and avoids the loss of glass caused by high temperature.

[0029] 3. The present invention contains both high-temperature antioxidant components such as ceramics and low-temperature antioxidant components such as glassy substances. It can ensure antioxidant performance in both high-temperature and low-temperature environments, and its operating temperature range is 500-1000 degrees Celsius.

[0030] 4. The present invention can be applied to a wide range of materials. It can be coated on the surface of graphite materials to increase the oxidation resistance of graphite materials, and can also be coated on the surface of metal materials to ensure that the metal materials are not oxidized at high temperatures and have strong interface bonding strength.

[0031] 5. The slurry configured in the present invention has good fluidity. For large-area graphite electrodes and metal plates, it can be poured directly. The slurry flows by itself under the action of gravity and spreads out to form an antioxidant and corrosion-resistant coating, which greatly saves the spraying construction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0033] Figure 1 This is a flow chart of an embodiment of a method for preparing a high-temperature resistant and anti-oxidation coating according to the present invention;

[0034] Figure 2 The graphs show the mass changes of the graphite electrode and the coated graphite electrodes of Examples 1 to 3 at 500 degrees Celsius;

[0035] Figure 3The graphs are of the mass changes of the graphite electrode and the coated graphite electrodes of Examples 1 to 3 at 700 degrees Celsius;

[0036] Figure 4 Graph showing mass changes of the graphite electrode and the coated graphite electrodes of Examples 1 to 3 at 900 degrees Celsius;

[0037] Figure 5 The graphs are of the mass changes of the graphite electrode and the coated graphite electrodes of Examples 1 to 3 at 1000 degrees Celsius;

[0038] Figure 6 This is a SEM image of the anti-oxidation coating on the graphite substrate after sintering at 500 degrees Celsius in Example 1;

[0039] Figure 7 This is a SEM image of the anti-oxidation coating on the graphite substrate after sintering at 900 degrees Celsius in Example 2;

[0040] Figure 8 This is a SEM image of the anti-oxidation coating on the graphite substrate after sintering at 1000 degrees Celsius in Example 3.

[0041] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0044] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B as an example", it includes solution A, or solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] This invention proposes a method for preparing a high-temperature, anti-oxidation coating. To ensure the long-term use of graphite and metal materials at high temperatures, an anti-oxidation coating is required. Under high-temperature conditions, the coating forms a dense protective layer that prevents oxygen atoms from penetrating the graphite / metal interface, protecting the substrate from oxidation at high temperatures.

[0046] In the embodiment of the present invention, Figure 1 As shown, the preparation method of the high temperature resistant and anti-oxidation coating comprises the following steps:

[0047] Step 1, weighing the raw materials according to the mass ratio, 50-70% of oxide ceramic powder, 20-40% of inorganic binder, 5-20% of caulking agent, 5%-20% of amorphous material, 0-5% of defoaming agent, and 0-5% of dispersant; wherein the oxide ceramic powder can specifically be 50%, 55%, 60%, 65% or 70%, the inorganic binder can be 20%, 25%, 30%, 35% or 40%, the caulking agent can be 5%, 10%, 15% or 20%, the amorphous material can be 5%, 10%, 15% or 20%, the defoaming agent can be 0%, 1%, 2%, 3%, 4% or 5%, and the dispersant can be 0%, 1%, 2%, 3%, 4% or 5%;

[0048] Step 2: Place the weighed powder into a dry drum for mixing at a speed of 30 rpm for 2 hours.

[0049] Step 3: Take out the mixed dry powder and add water to stir, adding 30 parts of water for every 100 parts of dry powder, and stir evenly to form a white slurry;

[0050] Step 4: After the evenly stirred slurry is allowed to stand for 2 hours, no obvious precipitation is observed;

[0051] Step 5: Evenly apply the slurry after standing on the surface of the material;

[0052] Step 6: Place the coated material at room temperature to dry for 30 minutes;

[0053] Step seven: placing the dried material in a high-temperature atmospheric environment for sintering.

[0054] The technical solution of the present invention uses oxide ceramic powder, inorganic binder, caulking agent, and amorphous material as the main raw materials, and adopts traditional ceramic powder as the main aggregate and antioxidant, which can not only ensure high-temperature oxidation resistance but also significantly reduce costs. The inorganic binder can achieve room temperature bonding, ensuring the bond strength after coating, and the caulking agent can further fill the pores formed by the ceramic aggregate, further improving the oxidation resistance of the coating. At high temperatures, the glassy material forms a viscous substance that fills the pores between the glassy material and the base material, completely isolating the air from the base material and achieving a high-temperature oxidation resistance effect.

[0055] Compared with traditional materials such as boric acid and glass, the technical solution of the present invention has a low glass content, and the main sealing role is played by the filler. The fine filler is filled between the ceramic aggregate particles to form a closed insulating layer, which greatly improves the high-temperature oxidation resistance and avoids the loss of glass caused by high temperature.

[0056] The technical solution of the present invention contains both high-temperature antioxidant components such as ceramics and low-temperature antioxidant components such as glassy substances. It can ensure antioxidant performance in both high-temperature and low-temperature environments, and has an operating temperature range of 500-1000 degrees Celsius.

[0057] The technical solution of the present invention can be applied to a wide range of materials. It can be coated on the surface of graphite materials to increase the oxidation resistance of the graphite materials, and can also be coated on the surface of metal materials to ensure that the metal materials are not oxidized at high temperatures and have strong interface bonding strength.

[0058] The slurry configured by the technical solution of the present invention has good fluidity. For large-area graphite electrodes and metal plates, it can be poured directly. The slurry flows by itself under the action of gravity and spreads out to form an antioxidant and corrosion-resistant coating, which greatly saves the spraying construction process.

[0059] In some embodiments, the order of placing the raw materials in step one is: first place the oxide ceramic material, then place the inorganic binder, and finally mix the caulking agent, amorphous substance, defoaming agent and dispersant together and pour them into the mixture of oxide ceramic material and inorganic binder. Specifically, ceramic powder is the base material with the highest content, and its priority placement helps the mixing effect of subsequent materials. The inorganic binder is placed second as the main binder, which helps to mix evenly with the ceramic powder, so that the surface of the ceramic powder can be better bonded with other auxiliary additives after being coated with the binder. This can avoid the situation where the binder and other auxiliary materials are easily agglomerated and unevenly dispersed when placed first, which ultimately affects the uniformity of the entire coating.

[0060] In some embodiments, the oxide ceramic powder includes bauxite and silica; specifically, bauxite is the mineral form of aluminum oxide. The use of bauxite can not only ensure the high temperature resistance of the ceramic powder but also reduce costs, while silica has good resistance to high temperature oxidation and can improve the high temperature resistance of the coating.

[0061] In some embodiments, the inorganic binder includes sodium pyrophosphate and sodium hexametaphosphate. Specifically, the inorganic binder using sodium pyrophosphate and sodium hexametaphosphate can significantly reduce the melting temperature of the amorphous material, thereby ensuring that it still exists in a wide temperature range and improving the oxidation resistance of materials (such as graphite electrodes) at low temperatures. This allows the coating to have both good high-temperature oxidation resistance and good low-temperature oxidation resistance, with the oxidation resistance temperature range reaching 500-1000 degrees Celsius.

[0062] In some embodiments, the amorphous material is primarily amorphous silicon oxide and amorphous zirconium oxide. Specifically, both amorphous silicon oxide and amorphous zirconium oxide have excellent high-temperature resistance and oxidation resistance. By using amorphous oxides, the coating can be made to adhere to the gaps between the particles within the operating temperature range, thereby isolating oxygen from contact with the graphite electrode and significantly improving the graphite electrode's oxidation resistance.

[0063] In some embodiments, the defoaming agent uses polyether-modified silicone oil. Specifically, the main function of the defoaming agent is to form a liquid ceramic coating that needs to be stirred evenly. During the spraying and stirring process of the spray gun, the viscous liquid easily forms bubbles, which is not conducive to the formation and density of the coating. Using polyether-modified silicone oil as a defoaming agent can improve the construction performance, facilitate the formation of the coating, and increase the density of the coating.

[0064] In some embodiments, the dispersant is polyethylene glycol. Since sodium pyrophosphate, sodium hexametaphosphate and ceramic powder are easy to agglomerate, especially microscopic agglomerates are difficult to disperse, polyethylene glycol is used as a dispersant to disperse the agglomerated particles, thereby improving the uniformity of the coating composition.

[0065] In some embodiments, the caulking agent utilizes nano-sized zircon. Specifically, nano-sized zircon can further fill even smaller pores, completely isolating oxygen from entering and enhancing the coating's antioxidant properties. Furthermore, the interaction between nano-sized zircon and amorphous materials (such as amorphous silicon oxide and amorphous zirconium oxide) ensures that tiny pores are completely filled while also preventing the inorganic material from becoming fluid at high temperatures due to its low viscosity.

[0066] In some embodiments, the diameter of the dry drum is 400 mm, and the volume of the powder in the dry mixing drum described in step 2 does not exceed 30% of the drum's volume. This arrangement allows sufficient space within the drum to allow the powders to mix during rotation and attract each other under electrostatic action, improving mixing uniformity and avoiding uneven mixing and easy agglomeration caused by too little space.

[0067] Optionally, before step 3, the mixed dry powder can be placed in a sealed plastic bag and left for at least 24 hours to allow the dry powder to rest and fully diffuse into each other to achieve complete uniformity. During the 24-hour diffusion period, the bag opening is sealed to prevent moisture from entering and causing clumping. Of course, in other embodiments, the dry powder mixed in step 2 can also be stirred directly.

[0068] In some embodiments, during the step 3 of adding water and stirring, 30% water is first added and stirred evenly to form a viscous solution, and then water is continuously added to dilute the solution until a uniform slurry coating is formed. This can quickly mix the slurry evenly and avoid clumping during stirring.

[0069] In some embodiments, the container needs to be covered and sealed during the standing process in step 4 to prevent water evaporation and loss. During the standing process, the oxide ceramic powder and other additives gradually diffuse in the water, the surface is completely wetted, the dispersant is evenly distributed between the particles and neutralizes the charge on the surface of the ceramic particles, forming a completely uniform solution without agglomeration and precipitation.

[0070] In some embodiments, in step five, when the material is graphite, the slurry after standing is poured directly onto the graphite surface, and the slurry is flattened and formed by itself under the action of gravity; when the material is metal, the metal surface is first shot blasted to remove rust, and then the slurry is sprayed onto the surface of the metal material using a compressed air spray gun.

[0071] In some embodiments, in step six, the formed anti-oxidation coating is dried at room temperature for 30 minutes, and the thickness of the film layer after drying is 20-30 microns.

[0072] In some embodiments, in step seven, the dried coating is directly sintered in a high-temperature working area at a temperature of 500-1000 degrees Celsius.

[0073] Optionally, a method for preparing a high-temperature resistant and anti-oxidation coating comprises the following steps:

[0074] Step 1, weighing materials: according to weight percentage, weigh 50-70% of oxide ceramic, 20-40% of inorganic binder, 5-20% of caulking agent, 5%-20% of amorphous material, 0-5% of defoaming agent, and 0-5% of dispersant.

[0075] Step 2: Dry mixing: Pour the weighed powder into a dry drum with a diameter of 400 mm for mixing. The drum rotates at a speed of 10 rpm and mixes for 2 hours.

[0076] Step 3: Prepare the slurry: Place the mixed dry powder into a container and add a small amount of water while stirring to form a slurry. Add 30 parts of water for every 100 parts of dry powder. First, add 10 parts of water to 100 parts of dry powder and stir thoroughly to form a viscous slurry. Then slowly add the remaining water, stirring constantly, until a uniform slurry is formed.

[0077] Step 4: Let the slurry stand: Let the evenly stirred slurry stand for 2 hours to allow the water to fully penetrate the surface of the fine ceramic particles and the surfaces of various additives, ensuring the uniformity of the slurry and no obvious precipitation after standing.

[0078] Step 5: Material surface coating: When the material is graphite, pour the slurry after standing directly on the graphite surface, and the slurry will flatten and form by itself under the action of gravity; when the material is metal, first shot blast the metal surface to remove rust, and then use a compressed air spray gun to evenly spray the slurry on the metal material surface.

[0079] Step 6: Drying: The formed anti-oxidation coating needs to be dried at room temperature for 30 minutes. The thickness of the film after drying is about 20-30 microns.

[0080] Step 7: Sintering: The dried coating is directly sintered in a high-temperature atmospheric working area at a temperature of 500-1000 degrees Celsius.

[0081] Optionally, in Example 1, a method for preparing a high-temperature resistant and anti-oxidation coating comprises the following steps:

[0082] Step 1, weighing materials: bauxite 50-70%, sodium pyrophosphate 20-40%, amorphous silicon oxide 5-10%, nano zircon 0-5%.

[0083] Step 2: Dry mixing: Pour the weighed powder into a dry drum with a diameter of 400 mm for mixing. The drum rotates at a speed of 10 rpm and mixes for 2 hours.

[0084] Step 3: Prepare the slurry: Place the mixed dry powder into a container and add a small amount of deionized water while stirring to form a slurry. Add 30 parts of water for every 100 parts of dry powder. First, add 10 parts of water to 100 parts of dry powder and stir thoroughly to form a viscous slurry. Then slowly add the remaining water, stirring while adding until a uniform slurry is formed. Finally, add 2-5% sodium pyrophosphate, 1-3% polyether-modified silicone oil, and 0-3% polyethylene glycol to the slurry.

[0085] Step 4: Let the slurry stand: Let the evenly stirred slurry stand for 2 hours to allow the liquid to fully impregnate the surface of the fine ceramic particles and the surfaces of various additives, ensuring the uniformity of the slurry and no obvious precipitation after standing.

[0086] Step 5: Material surface coating: When the material is graphite, pour the slurry after standing directly on the graphite surface, and the slurry will flatten and form by itself under the action of gravity; when the material is metal, first shot blast the metal surface to remove rust, and then use a compressed air spray gun to evenly spray the slurry on the metal material surface.

[0087] Step 6: Drying: The anti-oxidation coating needs to be dried at room temperature for 30 minutes. The thickness of the film after drying is about 20-30 microns.

[0088] Step 7: Sintering: The dried coating is directly sintered in a high-temperature atmospheric working area at a temperature of 500-1000 degrees Celsius.

[0089] Optionally, in Example 2, a method for preparing a high-temperature resistant and anti-oxidation coating comprises the following steps:

[0090] Step 1, weighing materials: bauxite 60-80%, amorphous silicon oxide 5-10%, nano zircon 0-5%, amorphous zircon oxide 0-5%.

[0091] Step 2: Dry mixing: Pour the weighed powder into a dry drum with a diameter of 400 mm for mixing. The drum rotates at a speed of 10 rpm and mixes for 2 hours.

[0092] Step 3, slurry preparation: Place the mixed dry powder into a container and add a small amount of water and stir to form a slurry. Add 30 parts of water for every 100 parts of dry powder. First, add 10 parts of water to 100 parts of dry powder and stir thoroughly to form a viscous slurry. Then slowly pour in the remaining water, stirring while adding until a uniform slurry is formed. Then add 10-30% sodium hexametaphosphate, 0-5% polyether-modified silicone oil, and 0-3% polyethylene glycol to the slurry.

[0093] Step 4: Let the slurry stand: Let the evenly stirred slurry stand for 2 hours to allow the liquid to fully impregnate the surface of the fine ceramic particles and the surfaces of various additives, ensuring the uniformity of the slurry and no obvious precipitation after standing.

[0094] Step 5: Material surface coating: When the material is graphite, pour the slurry after standing directly on the graphite surface, and the slurry will flatten and form by itself under the action of gravity; when the material is metal, first shot blast the metal surface to remove rust, and then use a compressed air spray gun to evenly spray the slurry on the metal material surface.

[0095] Step 6: Drying: The anti-oxidation coating after spraying needs to be dried at room temperature for 30 minutes. The thickness of the film after drying is about 20-30 microns.

[0096] Step 7: Sintering: The dried coating is directly sintered in a high-temperature atmospheric working area at a temperature of 500-1000 degrees Celsius.

[0097] Optionally, in Example 3, a high temperature resistant and oxidation resistant coating method comprises the following steps:

[0098] Step 1, weighing raw materials: bauxite 50-60%, silicon dioxide 10-30%, amorphous zirconia 5-10%, nano zircon 0-5%.

[0099] Step 2: Dry mixing: Pour the weighed powder into a dry drum with a diameter of 400 mm for mixing. The drum rotates at a speed of 10 rpm and mixes for 2 hours.

[0100] Step 1: Let it stand: Place the dry-mixed powder into a sealed plastic bag and let it stand for 24 hours to further ensure that the dry powder is evenly distributed.

[0101] Step 3, slurry preparation: Place the mixed dry powder into a container and add a small amount of water and stir to form a slurry. Add 30 parts of water for every 100 parts of dry powder. First, add 10 parts of water to 100 parts of dry powder and stir thoroughly to form a viscous slurry. Then slowly pour in the remaining water, stirring while adding until a uniform slurry is formed. Then add 5-20% sodium hexametaphosphate, 0-5% polyether-modified silicone oil, and 0-5% polyethylene glycol to the slurry.

[0102] Step 4: Let the slurry stand: Let the evenly stirred slurry stand for 2 hours to allow the water to fully penetrate the surface of the fine ceramic particles and the surfaces of various additives, ensuring the uniformity of the slurry and no obvious precipitation after standing.

[0103] Step 5: Material surface coating: When the material is graphite, pour the slurry after standing directly on the graphite surface, and the slurry will flatten and form by itself under the action of gravity; when the material is metal, first shot blast the metal surface to remove rust, and then use a compressed air spray gun to evenly spray the slurry on the metal material surface.

[0104] Step 6: Drying: The anti-oxidation coating after spraying needs to be dried at room temperature for 30 minutes. The thickness of the film after drying is about 20-30 microns.

[0105] Step 7: Sintering: The dried coating is directly sintered in a high-temperature atmospheric working area at a temperature of 500-1000 degrees Celsius.

[0106] like Figures 2 to 5 As shown, by testing a pure graphite electrode (graphite electrode without any coating), a graphite electrode with the coating of Example 1, a graphite electrode with the coating of Example 2, and a graphite electrode with the coating of Example 3 at 500 degrees Celsius, the following results are obtained: Figure 2 The graph showing the change in graphite electrode mass.

[0107] A pure graphite electrode (graphite electrode without any coating), a graphite electrode coated with Example 1, a graphite electrode coated with Example 2, and a graphite electrode coated with Example 3 were tested at 700 degrees Celsius to obtain the following: Figure 3 The graph showing the change in graphite electrode mass.

[0108] A pure graphite electrode (graphite electrode without any coating), a graphite electrode coated with Example 1, a graphite electrode coated with Example 2, and a graphite electrode coated with Example 3 were tested at 900 degrees Celsius to obtain the following: Figure 4 The graph showing the change in graphite electrode mass.

[0109] A pure graphite electrode (graphite electrode without any coating), a graphite electrode coated with Example 1, a graphite electrode coated with Example 2, and a graphite electrode coated with Example 3 were tested at 1000 degrees Celsius to obtain the following: Figure 5 The graph showing the change in graphite electrode mass.

[0110] from Figures 2 to 5It can be seen that the mass changes of the graphite electrode coated with Example 1, the graphite electrode coated with Example 2, and the graphite electrode coated with Example 3 are slight, that is, compared with the pure graphite electrode, the graphite electrode coated with Example 1, the graphite electrode coated with Example 2, and the graphite electrode coated with Example 3 have extremely low oxidation rates in the range of 500-1000 degrees Celsius, that is, the coating prepared using the technical solution of the present invention has high antioxidant performance in the range of 500-1000 degrees Celsius, and can effectively solve the problem of graphite oxidation under low and high temperature conditions.

[0111] in addition, Figure 6 This is the SEM image of the coating prepared in Example 1. Figure 7 This is the SEM image of the coating prepared in Example 1. Figure 8 This is the SEM image of the coating prepared in Example 3. Figures 6 to 8 It can be seen that the prepared coating has a dense microstructure, can isolate oxygen very well, and can greatly improve the oxidation resistance.

[0112] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a high temperature resistant and oxidation resistant coating, characterized in that: The steps include: Step 1: weigh the raw materials according to the mass ratio, 50-70% of oxide ceramic powder, 20-40% of inorganic binder, 5-20% of caulking agent, 5%-20% of amorphous material, 0-5% of defoaming agent, and 0-5% of dispersant; Step 2: Place the weighed powder into a dry drum for mixing at a speed of 30 rpm for 2 hours. Step 3: Take out the mixed dry powder and add water to stir, adding 30 parts of water for every 100 parts of dry powder, and stir evenly to form a white slurry; Step 4: Let the evenly stirred slurry stand for 2 hours, and no obvious precipitation occurs after standing; Step 5: Evenly apply the slurry after standing on the surface of the material; Step 6: Place the coated material at room temperature to dry for 30 minutes; Step seven: placing the dried material in a high-temperature atmospheric environment for sintering.

2. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 1, wherein: The order of placing the raw materials in step 1 is: first place the oxide ceramic material, then place the inorganic binder, and finally mix the filler, amorphous material, defoamer and dispersant together and pour them into the mixture of the oxide ceramic material and the inorganic binder.

3. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 1, wherein: The amorphous substance is mainly amorphous silicon oxide and amorphous zirconium oxide.

4. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 3, wherein: The oxide ceramic powder includes bauxite and silicon dioxide; The inorganic binder includes sodium pyrophosphate and sodium hexametaphosphate.

5. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 4, wherein: The defoaming agent is polyether modified silicone oil, the dispersant is polyethylene glycol, and the caulking agent is nano-level zircon.

6. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 1, wherein: The diameter of the dry drum is 400 mm, and the volume of the powder in the dry mixing barrel described in step 2 does not exceed 30% of the volume of the barrel.

7. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 1, wherein: During the process of adding water and stirring in step 3, 30% water is first added and stirred evenly to form a viscous solution, and then water is continuously added to dilute it until a uniform slurry coating is formed.

8. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 1, wherein: During the standing process in step 4, the container needs to be covered and sealed to prevent water evaporation and loss. During the standing process, the oxide ceramic powder and other additives gradually diffuse in the water, the surface is completely wetted, the dispersant is evenly distributed between the particles and neutralizes the charge on the surface of the ceramic particles, forming a completely uniform solution without agglomeration and precipitation; In step five, when the material is graphite, the slurry after standing is poured directly onto the graphite surface, and the slurry is flattened and formed by itself under the action of gravity; when the material is metal, the metal surface is first shot blasted to remove rust, and then the slurry is sprayed on the surface of the metal material using a compressed air spray gun.

9. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 1, wherein: In the step six, the formed anti-oxidation coating is dried at room temperature for 30 minutes, and the thickness of the film layer after drying is 20-30 microns.

10. The method for preparing a high temperature resistant and oxidation resistant coating according to claim 1, wherein: In step seven, the dried coating is directly sintered in a high-temperature working area at a temperature of 500-1000 degrees Celsius.

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