A high thermal conductivity refractory castable and its preparation method

Abstract

The present invention belongs to the technical field of refractory materials, and particularly relates to a high thermal conductivity refractory castable and a preparation method thereof. The high thermal conductivity refractory castable comprises the following components in parts by weight: 50 - 60 parts of silicon carbide; 10 - 15 parts of white fused alumina; 5 - 8 parts of calcium aluminate cement; 3 - 5 parts of modified graphite fiber; 2 - 3 parts of silica fume; 1 - 2 parts of binder; 0.3 - 0.5 part of water reducer; The high thermal conductivity refractory castable prepared by the present invention has good thermal conductivity, mechanical properties and high temperature dimensional stability, and is suitable for filling and repairing high thermal conductivity parts.

Description

Technical Field

[0001] The present invention belongs to the technical field of refractory materials, and particularly relates to a high thermal conductivity refractory castable and a preparation method thereof. Background Art

[0002] Refractory castable is an important unshaped refractory material, which is a mixture composed of refractory aggregate, powder, binder and admixture. It is mixed with water or liquid binder to form a mud that can be constructed by casting method. It has the advantages of simple production process, convenient construction and long service life, and is widely used in the lining materials of various high-temperature industrial furnaces with high thermal shock, strong mechanical impact and high-temperature stability; between the carbon bricks at the bottom of the blast furnace and the bottom sealing plate, and between the carbon bricks in the hearth and the cooling stave, high thermal conductivity materials are required to fill the gaps. When overhauling the blast furnace, high thermal conductivity materials are also required to repair the damaged parts of the carbon bricks. The traditional construction method is to fill the high thermal conductivity parts by ramming the carbon ramming material (high thermal conductivity material). Due to the low thermal conductivity of the raw materials of the carbon ramming material and the limitation of the ramming method during construction, there are many pores in the filled high thermal conductivity material, which greatly reduces the thermal conductivity of the material itself, thus affecting the service life of the blast furnace.

[0003] The Chinese patent application with the application number CN202010512525.9 discloses a silicon nitride composite high thermal conductivity castable, which is prepared by proportioning raw materials such as fused corundum, kyanite, silicon carbide, silicon nitride, silica fume, activated alumina powder, spherical asphalt, carbon black powder, carbon resin powder, carbon dispersant, antioxidant, organic fiber, and explosion-proof agent. During construction, a binder such as silica sol or calcium aluminate cement is added externally. Among them, carbon elements and carbon dispersants improve the thermal conductivity and slag resistance of the material; the Chinese patent with the application number CN202110286791.9 discloses a high thermal conductivity and wear-resistant castable prepared from secondary sillimanite bricks. The particle size and mass percentage of each raw material of the castable are as follows: secondary sillimanite bricks with a particle size ≤ 6mm are 40 - 50%, silicon carbide with a particle size ≤ 6mm is 20 - 30%, silica fume is 1 - 10%, calcium aluminate cement is 2 - 10%, and pyrophyllite powder with a particle size of 5μm is 2 - 20%. It also includes an admixture of 0.02 - 0.5% of the mass percentage of all the above components, realizing the preparation of a high thermal conductivity and wear-resistant material with high cost performance by using waste sillimanite brick resources; the above patents all improve the thermal conductivity of the castable by adding high thermal conductivity raw materials, but the thermal conductivity of the prepared castable still cannot meet the use requirements, and there is still a large room for improvement. Summary of the Invention

[0004] The object of the present invention is to provide a high thermal conductivity refractory castable and its preparation method in view of the deficiencies of the prior art. The high thermal conductivity refractory castable takes silicon carbide with high thermal conductivity as the main component, and white fused alumina, calcium aluminate cement, modified graphite fiber, silica fume, etc. as auxiliary components. Through reasonable proportioning, the prepared high thermal conductivity refractory castable has good thermal conductivity, mechanical properties and high temperature dimensional stability, and is suitable for filling and repairing high thermal conductivity parts.

[0005] The technical solution adopted by the present invention to achieve the above object is as follows:

[0006] A high thermal conductivity refractory castable, comprising the following components in parts by weight: 50 - 60 parts of silicon carbide; 10 - 15 parts of white fused alumina; 5 - 8 parts of calcium aluminate cement; 3 - 5 parts of modified graphite fiber; 2 - 3 parts of silica fume; 1 - 2 parts of binder; 0.3 - 0.5 part of water reducing agent;

[0007] Further, the silicon carbide includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 200 meshes in a mass ratio of 3 - 4:1 - 2:1.

[0008] Further, the white fused alumina includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 325 meshes in a mass ratio of 2 - 3:1 - 2:1.

[0009] Further, the particle size of the silica fume is 200 - 325 meshes; the binder is silica sol; the water reducing agent is one or a mixture of several of sodium tripolyphosphate, sodium hexametaphosphate, and calcium lignosulfonate.

[0010] In the technical solution of the present invention, the preparation method of the modified graphite fiber is as follows:

[0011] S1. Add graphite fiber into an ethanol aqueous solution, disperse it evenly, add 3 - aminopropyltriethoxysilane, adjust the pH value of the solution to 5 - 6, stir and react at 50 - 60 °C for 3 - 4 h. After the reaction is completed, filter, wash the filter residue with ethanol, and dry to obtain amino graphite fiber;

[0012] S2. Add amino graphite fiber into N,N - dimethylformamide, disperse it evenly, add 2,2 - dimethylolpropionic acid and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride, stir and react at 70 - 80 °C for 4 - 5 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain polyhydroxy graphite fiber;

[0013] S3. Add polyhydroxy graphite fibers into ethanol, disperse evenly, add sodium long-chain alkyl sulfonate chloride and potassium hydroxide, and stir and react at 60-70 °C for 3-4 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain modified graphite fibers.

[0014] Further, the mass ratio of the graphite fibers, 3-aminopropyltriethoxysilane, and ethanol aqueous solution in step S1 is 1:0.3-0.4:15-20.

[0015] Further, the mass ratio of the amino graphite fibers, 2,2-dimethylolpropionic acid, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride in step S2 is 1:0.2-0.25:0.1-0.15.

[0016] Further, the mass ratio of the polyhydroxy graphite fibers, sodium long-chain alkyl sulfonate chloride, and potassium hydroxide in step S3 is 1:0.5-0.6:0.08-0.1.

[0017] In the technical solution of the present invention, the preparation method of the sodium long-chain alkyl sulfonate chloride is as follows: Add toluene, sodium 4-hydroxybutyl sulfonate, 7-chloroheptanoic acid, and p-toluenesulfonic acid into a reaction vessel, stir evenly, heat up to 110 °C, reflux and react for 4-5 h, and collect the water generated by the reaction through a water separator. After the reaction is completed, remove toluene, add water and dichloromethane for extraction, and concentrate the aqueous phase under reduced pressure to obtain sodium long-chain alkyl sulfonate chloride.

[0018] Further, the molar ratio of the sodium 4-hydroxybutyl sulfonate, 7-chloroheptanoic acid, and p-toluenesulfonic acid is 1:1.1-1.2:0.01-0.02.

[0019] The present invention also provides a preparation method of a high thermal conductivity refractory castable, including the following steps: According to the mass ratio, mix silicon carbide, white fused alumina, calcium aluminate cement, modified graphite fibers, silica fume, binder, and water reducer evenly to obtain a high thermal conductivity refractory castable.

[0020] The present invention has the following beneficial effects:

[0021] The present invention modifies using high thermal conductivity graphite fibers as raw materials. First, it reacts with 3-aminopropyltriethoxysilane to introduce amino groups on the surface of the graphite fibers. Under the action of the condensing agent 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, the amino groups are condensed with 2,2-dimethylolpropionic acid, and the imino groups react with sodium long-chain alkylsulfonate chloride, successively introducing polyhydroxy groups and sodium long-chain alkylsulfonate groups onto the surface of the graphite fibers to obtain modified graphite fibers. The present invention adds the modified graphite fibers to the high thermal conductivity refractory castable. The flexible long-chain alkylsulfonate groups grafted on the surface of the modified graphite fibers can improve the dispersibility of the graphite fibers in the mixture, prevent their agglomeration, endow the castable with high thermal conductivity together with silicon carbide, and can also improve the brittleness of the graphite fibers and enhance the high-temperature dimensional stability of the castable. The polyhydroxy groups grafted on the surface of the modified graphite fibers can react with the silanol groups on the surface of the silica sol to promote the gelation of the silica sol and the formation of the silica sol network structure, which can improve the denseness of the castable and thus contribute to enhancing the comprehensive performance of the castable.

[0022] The high thermal conductivity refractory castable provided by the present invention has high thermal conductivity silicon carbide as the main component, and white fused alumina, calcium aluminate cement, modified graphite fibers, silica fume, etc. as auxiliary components. Through reasonable proportioning, the prepared high thermal conductivity refractory castable has good thermal conductivity, mechanical properties and high-temperature dimensional stability, and is suitable for filling and repairing high thermal conductivity parts. Detailed implementation manners

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments; the technical features designed in different implementation manners of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] In the technical solution of the present invention, the chemical reagents used are all commercially available. Among them, 3-aminopropyltriethoxysilane has a CAS number of 919-30-2; 2,2-dimethylolpropionic acid has a CAS number of 4767-03-7; 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride has a CAS number of 25952-53-8; potassium hydroxide has a CAS number of 1310-58-3; sodium 4-hydroxybutanesulfonate has a CAS number of 31465-25-5; 7-chloroheptanoic acid has a CAS number of 821-57-8; p-toluenesulfonic acid has a CAS number of 104-15-4; toluene has a CAS number of 108-88-3; N,N-dimethylformamide has a CAS number of 68-12-2; dichloromethane has a CAS number of 75-09-2; ethanol has a CAS number of 64-17-5; the content of silicon dioxide in the silica sol is 40 wt%; the diameter of the graphite fiber is 5 μm, the length is 5-10 mm, and it is purchased from Hebei Jingxin Technology Co., Ltd.

[0025] In the technical solution of the present invention, the preparation method of sodium long-chain alkylsulfonate chloride is as follows:

[0026] Add 550 mL of toluene, 20.0 g of sodium 4-hydroxybutanesulfonate, 20.6 g of 7-chloroheptanoic acid and 0.4 g of p-toluenesulfonic acid to the reaction vessel, stir evenly, heat up to 110 °C, reflux for 5 h, and collect the water generated by the reaction through a water separator. After the reaction is completed, remove the toluene, add water and dichloromethane for extraction, and concentrate the aqueous phase under reduced pressure to obtain 30.5 g of sodium long-chain alkylsulfonate chloride; the molar ratio of sodium 4-hydroxybutanesulfonate, 7-chloroheptanoic acid, and p-toluenesulfonic acid is 1:1.1:0.02; the reaction process is as follows:

[0027]

[0028] Sodium long-chain alkylsulfonate chloride: ESI(m / z): 323.8 [M+H] + , 1 1H-NMR(600 MHz, DMSO-d6, δ ppm): 4.13(t, J = 7.2 Hz, 2H), 3.25 - 3.32(m, 4H), 2.32(d, J = 6.8 Hz, 2H), 1.77 - 1.82(m, 2H), 1.61 - 1.66(m, 4H), 1.49 - 1.55(m, 4H), 1.33 - 1.38(m, 2H).

[0029] Example 1

[0030] A high thermal conductivity refractory castable includes the following components in parts by weight: 60 parts of silicon carbide; 13 parts of white fused alumina; 8 parts of calcium aluminate cement; 5 parts of modified graphite fiber; 3 parts of silica fume; 2 parts of binder; 0.4 part of water reducer;

[0031] Among them, the silicon carbide includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 200 mesh in a mass ratio of 4:2:1; the white fused alumina includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 325 mesh in a mass ratio of 3:2:1; the silicon micropowder has a particle size of 325 mesh; the binder is silica sol; the water reducing agent is sodium tripolyphosphate.

[0032] The preparation method of the modified graphite fiber is as follows:

[0033] S1. Add the graphite fiber into the ethanol aqueous solution, disperse it evenly, add 3 - aminopropyltriethoxysilane, adjust the pH value of the solution to 6, stir and react at 60 °C for 3 h. After the reaction is completed, filter, wash the filter residue with ethanol, and dry to obtain amino - graphite fiber; the mass ratio of graphite fiber, 3 - aminopropyltriethoxysilane, and ethanol aqueous solution is 1:0.4:20;

[0034] S2. Add the amino - graphite fiber into N,N - dimethylformamide, disperse it evenly, add 2,2 - dimethylolpropionic acid and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride, stir and react at 80 °C for 5 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain polyhydroxy - graphite fiber; the mass ratio of amino - graphite fiber, 2,2 - dimethylolpropionic acid, and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride is 1:0.25:0.15;

[0035] S3. Add the polyhydroxy - graphite fiber into ethanol, disperse it evenly, add long - chain alkyl sulfonate chloride and potassium hydroxide, stir and react at 70 °C for 4 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain the modified graphite fiber; the mass ratio of polyhydroxy - graphite fiber, long - chain alkyl sulfonate chloride, and potassium hydroxide is 1:0.6:0.1.

[0036] A preparation method of a high - thermal - conductivity refractory castable includes the following steps: According to the mass ratio, mix silicon carbide, white fused alumina, calcium aluminate cement, modified graphite fiber, silicon micropowder, binder, and water - reducing agent evenly to obtain the high - thermal - conductivity refractory castable.

[0037] Example 2

[0038] A high - thermal - conductivity refractory castable includes the following components in parts by weight: 55 parts of silicon carbide; 15 parts of white fused alumina; 6 parts of calcium aluminate cement; 4 parts of modified graphite fiber; 2 parts of silicon micropowder; 1.5 parts of binder; 0.5 part of water - reducing agent;

[0039] Among them, the silicon carbide includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 200 mesh in a mass ratio of 3:1.5:1; the white fused alumina includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 325 mesh in a mass ratio of 2.5:1.5:1; the silicon micropowder has a particle size of 270 mesh; the binder is silica sol; the water reducing agent is calcium lignosulfonate.

[0040] The preparation method of the modified graphite fiber is as follows:

[0041] S1. Add the graphite fiber into the ethanol aqueous solution, disperse it evenly, add 3 - aminopropyltriethoxysilane, adjust the pH value of the solution to 5.5, stir and react at 50 °C for 4 h. After the reaction is completed, filter, wash the filter residue with ethanol, and dry to obtain amino - graphite fiber; the mass ratio of the graphite fiber, 3 - aminopropyltriethoxysilane, and ethanol aqueous solution is 1:0.35:18;

[0042] S2. Add the amino - graphite fiber into N,N - dimethylformamide, disperse it evenly, add 2,2 - dimethylolpropionic acid and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride, stir and react at 75 °C for 4 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain polyhydroxy - graphite fiber; the mass ratio of the amino - graphite fiber, 2,2 - dimethylolpropionic acid, and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride is 1:0.2:0.1;

[0043] S3. Add the polyhydroxy - graphite fiber into ethanol, disperse it evenly, add long - chain alkyl sulfonate chloride and potassium hydroxide, stir and react at 60 °C for 3.5 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain the modified graphite fiber; the mass ratio of the polyhydroxy - graphite fiber, long - chain alkyl sulfonate chloride, and potassium hydroxide is 1:0.55:0.09.

[0044] The preparation method of a high - thermal - conductivity refractory castable is the same as that in Example 1.

[0045] Example 3

[0046] A high - thermal - conductivity refractory castable, comprising the following components in parts by weight: 50 parts of silicon carbide; 10 parts of white fused alumina; 5 parts of calcium aluminate cement; 3 parts of modified graphite fiber; 2.5 parts of silicon micropowder; 1 part of binder; 0.3 part of water reducing agent;

[0047] Among them, the silicon carbide includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 200 mesh in a mass ratio of 3.5:1:1; the white fused alumina includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 325 mesh in a mass ratio of 2:1:1; the silicon micropowder has a particle size of 200 mesh; the binder is silica sol; the water reducing agent is sodium hexametaphosphate.

[0048] The preparation method of the modified graphite fiber is as follows:

[0049] S1. Add the graphite fiber into the ethanol aqueous solution, disperse it evenly, add 3 - aminopropyltriethoxysilane, adjust the pH value of the solution to 5, stir and react at 55 °C for 3.5 h. After the reaction is completed, filter, wash the filter residue with ethanol, and dry to obtain amino - graphite fiber; the mass ratio of the graphite fiber, 3 - aminopropyltriethoxysilane, and ethanol aqueous solution is 1:0.3:15;

[0050] S2. Add the amino - graphite fiber into N,N - dimethylformamide, disperse it evenly, add 2,2 - dimethylolpropionic acid and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride, stir and react at 70 °C for 4.5 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain polyhydroxy - graphite fiber; the mass ratio of the amino - graphite fiber, 2,2 - dimethylolpropionic acid, and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride is 1:0.23:0.13;

[0051] S3. Add the polyhydroxy - graphite fiber into ethanol, disperse it evenly, add long - chain alkyl sulfonate chloride and potassium hydroxide, stir and react at 65 °C for 3 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain the modified graphite fiber; the mass ratio of the polyhydroxy - graphite fiber, long - chain alkyl sulfonate chloride, and potassium hydroxide is 1:0.5:0.08.

[0052] The preparation method of a high - thermal - conductivity refractory castable is the same as that of Example 1.

[0053] Comparative Example 1

[0054] Compared with Example 1, in this comparative example, the modified graphite fiber in the components is replaced with polyhydroxy - graphite fiber.

[0055] A high - thermal - conductivity refractory castable includes the following components in parts by weight: 60 parts of silicon carbide; 13 parts of white fused alumina; 8 parts of calcium aluminate cement; 5 parts of polyhydroxy - graphite fiber; 3 parts of silicon micropowder; 2 parts of binder; 0.4 part of water reducing agent;

[0056] Among them, the silicon carbide includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 200 mesh in a mass ratio of 4:2:1; the white fused alumina includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 325 mesh in a mass ratio of 3:2:1; the silicon micropowder has a particle size of 325 mesh; the binder is silica sol; the water reducing agent is sodium tripolyphosphate.

[0057] The preparation method of the polyhydroxy graphite fiber is as follows:

[0058] S1. The same as step S1 of Example 1;

[0059] S2. The same as step S1 of Example 1.

[0060] The preparation method of a high thermal conductivity refractory castable is the same as that of Example 1.

[0061] Comparative Example 2

[0062] Compared with Example 1, in this comparative example, the modified graphite fiber in the components is replaced with amino graphite fiber.

[0063] A high thermal conductivity refractory castable includes the following components in parts by weight: 60 parts of silicon carbide; 13 parts of white fused alumina; 8 parts of calcium aluminate cement; 5 parts of amino graphite fiber; 3 parts of silicon micropowder; 2 parts of binder; 0.4 part of water reducing agent;

[0064] Among them, the silicon carbide includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 200 mesh in a mass ratio of 4:2:1; the white fused alumina includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 325 mesh in a mass ratio of 3:2:1; the silicon micropowder has a particle size of 325 mesh; the binder is silica sol; the water reducing agent is sodium tripolyphosphate.

[0065] The preparation method of the amino graphite fiber is the same as step S1 of Example 1.

[0066] The preparation method of a high thermal conductivity refractory castable is the same as that of Example 1.

[0067] Comparative Example 3

[0068] Compared with Example 1, in this comparative example, the modified graphite fiber in the components is replaced with graphite fiber.

[0069] A high thermal conductivity refractory castable includes the following components in parts by weight: 60 parts of silicon carbide; 13 parts of white fused alumina; 8 parts of calcium aluminate cement; 5 parts of graphite fiber; 3 parts of silicon micropowder; 2 parts of binder; 0.4 part of water reducing agent;

[0070] The silicon carbide includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 200 mesh, with a mass ratio of 4:2:1; the white fused alumina includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 325 mesh, with a mass ratio of 3:2:1; the silicon micropowder has a particle size of 325 mesh; the binder is silica sol; the water reducing agent is sodium tripolyphosphate.

[0071] The preparation method of a high - thermal - conductivity refractory castable is the same as that of Example 1.

[0072] Performance testing

[0073] Add 5% of the weight of the castable water to the high - thermal - conductivity refractory castables prepared in Examples 1 - 3 and Comparative Examples 1 - 3 respectively, mix evenly, vibrate and form, demold after curing at room temperature for 24 h, and test the bulk density, flexural strength, compressive strength, linear change rate and thermal conductivity of the samples. Among them, the bulk density refers to the YB / T 5200 - 1993 standard; the flexural strength refers to the GB / T3002 - 2017 standard; the compressive strength refers to the GB / T 34218 - 2017 standard; the linear change rate refers to the GB / T5988 - 2007 standard; the results are shown in Table 1 below.

[0074] Table 1 Performance test results

[0075]

[0076] As can be seen from the results in Table 1, the high - thermal - conductivity refractory castables prepared in Examples 1 - 3 of the present invention have good thermal conductivity, mechanical properties and high - temperature dimensional stability. Compared with Comparative Examples 1 - 3, the modified graphite fibers added in Example 1 of the present invention are grafted with long - chain alkyl sulfonate groups and polyhydroxy groups on the surface. Among them, the flexible long - chain alkyl sulfonate groups can improve the brittleness of the graphite fibers, improve the high - temperature dimensional stability of the castable, and can also improve the dispersion of the graphite fibers in the mixture, and together with silicon carbide, enhance the thermal conductivity of the castable; the polyhydroxy groups can react with the silicon hydroxyl groups on the surface of silica sol, promote the gelation of silica sol and the formation of the silica sol network structure, can improve the compactness of the castable, and thus contribute to improving the comprehensive performance of the castable.

[0077] It should be noted that in this document, terms such as "including", "comprising", or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements that are inherent to such a process, method, article, or device; although embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high thermal conductivity refractory castable, characterized in that, It includes the following components in parts by weight: 50 - 60 parts of silicon carbide; 10 - 15 parts of white fused alumina; 5 - 8 parts of calcium aluminate cement; 3 - 5 parts of modified graphite fiber; 2 - 3 parts of silica fume; 1 - 2 parts of binder; 0.3 - 0.5 part of water reducing agent. The preparation method of the said modified graphite fiber is as follows: S1. Add graphite fiber into the ethanol aqueous solution, disperse evenly, add 3 - aminopropyltriethoxysilane, adjust the pH value of the solution to 5 - 6, stir and react at 50 - 60 °C for 3 - 4 h. After the reaction is completed, filter, wash the filter residue with ethanol, and dry to obtain amino graphite fiber. S2. Add amino graphite fiber into N,N - dimethylformamide, disperse evenly, add 2,2 - dimethylolpropionic acid and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride, stir and react at 70 - 80 °C for 4 - 5 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain polyhydroxy graphite fiber. S3. Add polyhydroxy graphite fiber into ethanol, disperse evenly, add sodium long - chain alkyl sulfonate chloride and potassium hydroxide, stir and react at 60 - 70 °C for 3 - 4 h. After the reaction is completed, filter, wash the filter residue with water and ethanol in sequence, and dry to obtain modified graphite fiber. The preparation method of the sodium long - chain alkyl sulfonate chloride described in step S3 is: Add toluene, sodium 4 - hydroxybutyl sulfonate, 7 - chloroheptanoic acid and p - toluenesulfonic acid into the reaction vessel, stir evenly, heat up to 110 °C, reflux and react for 4 - 5 h, and collect the water generated in the reaction through a water separator. After the reaction is completed, remove toluene, add water and dichloromethane for extraction, and concentrate the aqueous phase under reduced pressure to obtain sodium long - chain alkyl sulfonate chloride.

2. The high thermal conductivity refractory castable according to claim 1, characterized in that The molar ratio of the sodium 4 - hydroxybutyl sulfonate, 7 - chloroheptanoic acid, and p - toluenesulfonic acid is 1:1.1 - 1.2:0.01 - 0.

02.

3. A high thermal conductivity refractory castable according to claim 1, characterized in that, The mass ratio of the graphite fiber, 3 - aminopropyltriethoxysilane, and ethanol aqueous solution described in step S1 is 1:0.3 - 0.4:15 - 20.

4. A high thermal conductivity refractory castable according to claim 1, characterized in that, The mass ratio of the amino graphite fiber, 2,2 - dimethylolpropionic acid, and 1 - ethyl - (3 - dimethylaminopropyl) carbodiimide hydrochloride described in step S2 is 1:0.2 - 0.25:0.1 - 0.

15.

5. A high thermal conductivity refractory castable according to claim 1, characterized in that, The mass ratio of the polyhydroxy graphite fiber, sodium long - chain alkyl sulfonate chloride, and potassium hydroxide described in step S3 is 1:0.5 - 0.6:0.08 - 0.

1.

6. The high thermal conductivity refractory castable according to claim 1, characterized in that, The silicon carbide includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 200 meshes in a mass ratio of 3 - 4:1 - 2:

1.

7. A high thermal conductivity refractory castable according to claim 1, characterized in that, The white fused alumina includes particles with a particle size of 1 - 3 mm, particles with a particle size of 0 - 1 mm, and fine powder with a particle size of 325 meshes in a mass ratio of 2 - 3:1 - 2:

1.

8. A high thermal conductivity refractory castable according to claim 1, characterized in that, The particle size of the silica fume is 200 - 325 meshes; the binder is silica sol; the water reducing agent is one or a mixture of sodium tripolyphosphate, sodium hexametaphosphate, and calcium lignosulfonate.

9. The preparation method of a high thermal conductivity refractory castable according to any one of claims 1-8, characterized in that, It includes the following steps: According to the mass ratio, mix silicon carbide, white fused alumina, calcium aluminate cement, modified graphite fiber, silica fume, binder, and water reducer evenly to obtain a high thermal conductivity refractory castable.

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