High-strength refractory castable based on mullite and preparation process thereof

Abstract

This invention relates to the field of refractory castables, specifically to a high-strength refractory castable based on mullite modification and its preparation process; it addresses the problems of low strength and poor wear resistance in existing refractory castables; this refractory castable incorporates niobium-zirconium alloy and benzoxazine-PAMAM copolymer. The benzoxazine-PAMAM copolymer encapsulates the matrix in a three-dimensional network structure, thereby improving adhesion. After sintering, a carbon layer is formed between the matrix particles, enhancing the overall density of the material. The niobium-zirconium alloy fills the micropores in the refractory castable matrix, reducing porosity and stress concentration, significantly improving room temperature compressive and flexural strength, and maintaining long-term high-temperature strength. This ensures that the refractory castable remains stable under harsh environments such as high temperature, high pressure, and corrosion, thereby extending its service life and improving production safety.

Description

Technical Field

[0001] This invention relates to the field of refractory castables, specifically to high-strength refractory castables based on mullite modification and their preparation process. Background Technology

[0002] Traditional refractory castables have limitations in terms of high strength and wear resistance, making them unsuitable for demanding working conditions under prolonged high temperatures. Against this backdrop, modifying refractory castables to improve their performance has become an important research direction. Mullite, as a common high-temperature stable material, exhibits excellent application potential in modified refractory castables due to its high heat resistance and chemical stability. This invention provides a mullite-modified high-strength refractory castable. By adding mullite, niobium-zirconium alloy, and benzoxazine-PAMAM copolymer, the castable can better fill complex-shaped molds, improving construction efficiency. Summary of the Invention

[0003] In order to overcome the above-mentioned technical problems, the present invention aims to provide: a high-strength refractory castable based on mullite and its preparation process, which solves the problems of low strength and poor wear resistance of existing refractory castables.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] In a first aspect, this application provides a mullite-modified high-strength refractory castable, comprising the following parts by weight:

[0006] 15-25 parts mullite, 5-10 parts zirconium oxide fiber, 15-25 parts silicon carbide, 30-40 parts mullite fiber, 5-10 parts aluminum dihydrogen phosphate, 5-10 parts benzoxazine-PAMAM copolymer, 10-20 parts silica powder, 3-5 parts niobium-zirconium alloy powder, and 20-30 parts alumina powder.

[0007] The benzoxazine-PAMAM copolymer is prepared by the following steps:

[0008] Step A1: Eugenol, p-phenylenediamine, paraformaldehyde, toluene, and N,N-dimethylformamide were added to a three-necked flask equipped with a reflux condenser and a thermometer. Nitrogen gas was introduced for protection, and the mixture was refluxed at 100-105℃ for 4-5 hours. The mixture was then cooled to 24-26℃, washed three times with sodium hydroxide solution, and then washed three times with deionized water. The organic phase was collected by separation, and toluene and N,N-dimethylformamide were removed by rotary evaporation. The mixture was then placed in a drying oven and vacuum dried at 40℃ for 16 hours to obtain dienyl dibenzoxazine.

[0009]

[0010] Step A2: Add diethylamine and methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 5-10 min, add diene dibenzoxazine, transfer to an oil bath and stir to react at 25-35℃ for 24 h, and distill under reduced pressure at 60℃ to obtain intermediate product 1.

[0011] Step A3: Add intermediate product 1 and methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 5-10 min, add ethyl acrylate dropwise, controlling the dropwise addition time to 30 min, add ethylenediamine-methanol solution, controlling the dropwise addition time to 30 min, transfer to an oil bath and stir the reaction at 25-35℃ for 24 h, distill under reduced pressure at 60℃, wash with ethyl acetate 3-5 times, distill under reduced pressure for 3 h to obtain benzoxazine-PAMAM copolymer.

[0012] As a further embodiment of the present invention: the ratio of eugenol, p-phenylenediamine, paraformaldehyde, toluene and N,N-dimethylformamide used in step A1 is 0.1-0.2 mol: 0.1-0.2 mol: 57.66-119.31 g: 160-320 mL: 40-80 mL.

[0013] As a further aspect of the present invention: the molar concentration of the sodium hydroxide solution in step A1 is 0.5 mol / L.

[0014] As a further aspect of the present invention: the CAS number of the paraformaldehyde mentioned in step A1 is 30525-89-4.

[0015] As a further embodiment of the present invention: the ratio of diethylamine, methanol and diene dibenzoxazine used in step A2 is 0.015-0.045 mol: 100-300 mL: 0.05-0.15 mol.

[0016] As a further aspect of the present invention: the ratio of intermediate product 1, methanol, ethyl acrylate and ethylenediamine-methanol solution in step A3 is 47.2-94.4 mmol: 80-160 mL: 0.189-0.378 mol: 40-80 mL.

[0017] As a further aspect of the present invention: the ratio of ethylenediamine to methanol in the ethylenediamine-methanol solution in step A3 is 0.7-1.4 mol: 40-80 mL.

[0018] Secondly, this application provides a preparation process for mullite-modified high-strength refractory castables, including the following steps:

[0019] Step 1: Weigh out 15-25 parts by weight of mullite, 5-10 parts by weight of zirconium oxide fiber, 15-25 parts by weight of silicon carbide, 30-40 parts by weight of mullite fiber, 5-10 parts by weight of aluminum dihydrogen phosphate, 5-10 parts by weight of benzoxazine-PAMAM copolymer, 10-20 parts by weight of silica powder, 3-5 parts by weight of niobium-zirconium alloy powder, and 20-30 parts by weight of alumina powder, and set aside. The zirconium oxide fiber has a length of 2.1-3.0 mm and a diameter of 0.003-0.008 mm; the mullite fiber has a length of 3-5 mm and a diameter of 0.005-0.015 mm; the niobium-zirconium alloy powder has a particle size of 0.015-0.053 mm; and the zirconium content in the niobium-zirconium alloy powder is 25%.

[0020] Step 2: Mix mullite, zirconium oxide fiber, silicon carbide, mullite fiber, aluminum dihydrogen phosphate, benzoxazine-PAMAM copolymer, silica powder, niobium-zirconium alloy powder and alumina powder to obtain a high-strength refractory castable based on mullite modification.

[0021] The beneficial effects of this invention are:

[0022] This invention relates to a mullite-modified high-strength refractory castable, which uses a synthesized benzoxazine-PAMAM copolymer as a binder. The benzoxazine-PAMAM copolymer combines the heat resistance of benzoxazine resin with the dendritic structure of PAMAM to enhance adhesion. The addition of niobium-zirconium alloy powder improves the strength of the refractory castable. Through synergistic effects, a high-strength, high-wear-resistant refractory castable is formed, suitable for industries such as steel, building materials, and petrochemicals.

[0023] To prepare a high-strength refractory castable based on mullite modification, a benzoxazine-PAMAM copolymer was first synthesized. Dienyl dibenzoxazine was synthesized using eugenol, p-phenylenediamine, and paraformaldehyde. Then, a Michael addition reaction was performed between the amino group of ethylenediamine and the alkenyl group of the dienyl dibenzoxazine to synthesize an amino-containing intermediate, intermediate 1. Intermediate 1 was reacted with ethyl acrylate to introduce ester groups. These ester groups then underwent an amidation reaction with the amino group of ethylenediamine to form amide bonds, generating the benzoxazine-PAMAM copolymer. Its three-dimensional topological structure allows for stronger physical entanglement with the matrix, encapsulating the matrix within a three-dimensional network structure. This enhances adhesion, and after sintering, a carbon layer is formed between the matrix particles, improving the overall density of the material. Benzoxazine has high heat resistance and, under heating conditions, it will open the ring to form a three-dimensional cross-linked network structure, forming a double-layer coating with PAMAM. After sintering, a dense carbon layer is formed, further enhancing the adhesion effect. The excellent chemical stability of niobium-zirconium alloy can reduce the erosion of the castable matrix by high-temperature liquid, avoid the sudden drop in strength of the matrix due to dissolution, and indirectly maintain long-term high-temperature strength. This allows the overall refractory castable to maintain good structural integrity and mechanical properties under high-temperature conditions, effectively meeting the requirements of various harsh industrial environments. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1:

[0025] This embodiment describes the preparation process of mullite-modified high-strength refractory castable, including the following steps:

[0026] Step A1: 0.1 mol eugenol, 0.1 mol p-phenylenediamine, 57.66 g paraformaldehyde, 160 mL toluene, and 40 mL N,N-dimethylformamide were added to a three-necked flask equipped with a reflux condenser and a thermometer. Nitrogen gas was introduced for protection, and the mixture was refluxed at 100 °C for 4 h. After cooling to 24 °C, the mixture was washed three times with sodium hydroxide solution and then three times with deionized water. The organic phase was collected by separation, and toluene and N,N-dimethylformamide were removed by rotary evaporation. The mixture was then placed in a drying oven and vacuum dried at 40 °C for 16 h to obtain dienyl dibenzoxazine.

[0027] Step A2: Add 0.015 mol of diethylamine and 100 mL of methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 5 min, add 0.05 mol of dienyl dibenzoxazine, transfer to an oil bath and stir at 25 °C for 24 h, then distill under reduced pressure at 60 °C to obtain intermediate product 1;

[0028] Step A3: Add 47.2 mmol of intermediate 1 and 80 mL of methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 5-10 min, add 0.189 mol of ethyl acrylate dropwise, controlling the addition time to 30 min, add 40 mL of ethylenediamine-methanol solution, controlling the addition time to 30 min, transfer to an oil bath and stir at 25 °C for 24 h, distill under reduced pressure at 60 °C, wash three times with ethyl acetate, and distill under reduced pressure for 3 h to obtain benzoxazine-PAMAM copolymer;

[0029] Step A4: Weigh out 15 parts by weight of mullite, 5 parts by weight of zirconium oxide fiber, 15 parts by weight of silicon carbide, 30 parts by weight of mullite fiber, 5 parts by weight of aluminum dihydrogen phosphate, 5 parts by weight of benzoxazine-PAMAM copolymer, 10 parts by weight of silica powder, 3 parts by weight of niobium-zirconium alloy powder, and 20 parts by weight of alumina powder, and set aside for later use; wherein, the zirconium oxide fiber has a length of 2.1-3.0 mm and a diameter of 0.003-0.008 mm; the mullite fiber has a length of 3-5 mm and a diameter of 0.005-0.015 mm; the niobium-zirconium alloy powder has a particle size of 0.015-0.053 mm; and the zirconium content in the niobium-zirconium alloy powder is 25%;

[0030] Step A5: Mix mullite, zirconium oxide fiber, silicon carbide, mullite fiber, aluminum dihydrogen phosphate, benzoxazine-PAMAM copolymer, silica powder, niobium-zirconium alloy powder and alumina powder to obtain a high-strength refractory castable based on mullite modification. Example 2:

[0031] This embodiment describes the preparation process of mullite-modified high-strength refractory castable, including the following steps:

[0032] Step A1: 0.15 mol eugenol, 0.15 mol p-phenylenediamine, 88.485 g paraformaldehyde, 240 mL toluene, and 60 mL N,N-dimethylformamide were added to a three-necked flask equipped with a reflux condenser and a thermometer. Nitrogen gas was introduced for protection, and the mixture was refluxed at 103 °C for 4.5 h. After cooling to 25 °C, the mixture was washed three times with sodium hydroxide solution and then three times with deionized water. The organic phase was collected by separation, and toluene and N,N-dimethylformamide were removed by rotary evaporation. The mixture was then placed in a drying oven and vacuum dried at 40 °C for 16 h to obtain dienyl dibenzoxazine.

[0033] Step A2: Add 0.03 mol of diethylamine and 200 mL of methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 7 min, add 0.1 mol of dienyl dibenzoxazine, transfer to an oil bath and stir at 30 °C for 24 h, then distill under reduced pressure at 60 °C to obtain intermediate product 1;

[0034] Step A3: Add 70.8 mmol of intermediate 1 and 120 mL of methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 5-10 min, add 0.284 mol of ethyl acrylate dropwise, controlling the dropwise addition time to 30 min, add 60 mL of ethylenediamine-methanol solution, controlling the dropwise addition time to 30 min, transfer to an oil bath and stir the reaction at 30 °C for 24 h, distill under reduced pressure at 60 °C, wash with ethyl acetate 4 times, distill under reduced pressure for 3 h to obtain benzoxazine-PAMAM copolymer;

[0035] Step A4: Weigh out 20 parts by weight of mullite, 7.5 parts by weight of zirconium oxide fiber, 20 parts by weight of silicon carbide, 35 parts by weight of mullite fiber, 7.5 parts by weight of aluminum dihydrogen phosphate, 7.5 parts by weight of benzoxazine-PAMAM copolymer, 15 parts by weight of silica powder, 4 parts by weight of niobium-zirconium alloy powder, and 25 parts by weight of alumina powder, and set aside for later use; wherein, the zirconium oxide fiber has a length of 2.1-3.0 mm and a diameter of 0.003-0.008 mm; the mullite fiber has a length of 3-5 mm and a diameter of 0.005-0.015 mm; the niobium-zirconium alloy powder has a particle size of 0.015-0.053 mm; and the zirconium content in the niobium-zirconium alloy powder is 25%;

[0036] Step A5: Mix mullite, zirconium oxide fiber, silicon carbide, mullite fiber, aluminum dihydrogen phosphate, benzoxazine-PAMAM copolymer, silica powder, niobium-zirconium alloy powder and alumina powder to obtain a high-strength refractory castable based on mullite modification. Example 3:

[0037] This embodiment describes the preparation process of mullite-modified high-strength refractory castable, including the following steps:

[0038] Step A1: 0.2 mol eugenol, 0.2 mol p-phenylenediamine, 119.31 g paraformaldehyde, 320 mL toluene, and 80 mL N,N-dimethylformamide were added to a three-necked flask equipped with a reflux condenser and a thermometer. Nitrogen gas was introduced for protection, and the mixture was refluxed at 105 °C for 5 h. After cooling to 26 °C, the mixture was washed three times with sodium hydroxide solution and then three times with deionized water. The organic phase was collected by separation, and toluene and N,N-dimethylformamide were removed by rotary evaporation. The mixture was then placed in a drying oven and vacuum dried at 40 °C for 16 h to obtain dienyl dibenzoxazine.

[0039] Step A2: Add 0.045 mol of diethylamine and 300 mL of methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 10 min, add 0.15 mol of diene dibenzoxazine, transfer to an oil bath and stir at 35 °C for 24 h, then distill under reduced pressure at 60 °C to obtain intermediate product 1;

[0040] Step A3: Add 94.4 mmol of intermediate 1 and 160 mL of methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 10 min, add 0.378 mol of ethyl acrylate dropwise, controlling the dropwise addition time to 30 min, add 80 mL of ethylenediamine-methanol solution, controlling the dropwise addition time to 30 min, transfer to an oil bath and stir the reaction at 35 °C for 24 h, distill under reduced pressure at 60 °C, wash with ethyl acetate 5 times, distill under reduced pressure for 3 h to obtain benzoxazine-PAMAM copolymer;

[0041] Step A4: Weigh out 25 parts by weight of mullite, 10 parts by weight of zirconium oxide fiber, 25 parts by weight of silicon carbide, 40 parts by weight of mullite fiber, 10 parts by weight of aluminum dihydrogen phosphate, 10 parts by weight of benzoxazine-PAMAM copolymer, 20 parts by weight of silica powder, 5 parts by weight of niobium-zirconium alloy powder, and 30 parts by weight of alumina powder, and set aside for later use; wherein, the zirconium oxide fiber has a length of 2.1-3.0 mm and a diameter of 0.003-0.008 mm; the mullite fiber has a length of 3-5 mm and a diameter of 0.005-0.015 mm; the niobium-zirconium alloy powder has a particle size of 0.015-0.053 mm; and the zirconium content in the niobium-zirconium alloy powder is 25%;

[0042] Step A5: Mix mullite, zirconium oxide fiber, silicon carbide, mullite fiber, aluminum dihydrogen phosphate, benzoxazine-PAMAM copolymer, silica powder, niobium-zirconium alloy powder and alumina powder to obtain a high-strength refractory castable based on mullite modification.

[0043] Comparative Example 1:

[0044] This comparative example illustrates the preparation process of mullite-modified high-strength refractory castable, including the following steps:

[0045] Step A1: 0.2 mol eugenol, 0.2 mol p-phenylenediamine, 119.31 g paraformaldehyde, 320 mL toluene, and 80 mL N,N-dimethylformamide were added to a three-necked flask equipped with a reflux condenser and a thermometer. Nitrogen gas was introduced for protection, and the mixture was refluxed at 105 °C for 5 h. After cooling to 26 °C, the mixture was washed three times with sodium hydroxide solution and then three times with deionized water. The organic phase was collected by separation, and toluene and N,N-dimethylformamide were removed by rotary evaporation. The mixture was then placed in a drying oven and vacuum dried at 40 °C for 16 h to obtain dienyl dibenzoxazine.

[0046] Step A2: Add 0.045 mol of diethylamine and 300 mL of methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 10 min, add 0.15 mol of diene dibenzoxazine, transfer to an oil bath and stir at 35 °C for 24 h, then distill under reduced pressure at 60 °C to obtain intermediate product 1;

[0047] Step A3: Add 94.4 mmol of intermediate 1 and 160 mL of methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 10 min, add 0.378 mol of ethyl acrylate dropwise, controlling the dropwise addition time to 30 min, add 80 mL of ethylenediamine-methanol solution, controlling the dropwise addition time to 30 min, transfer to an oil bath and stir the reaction at 35 °C for 24 h, distill under reduced pressure at 60 °C, wash with ethyl acetate 5 times, distill under reduced pressure for 3 h to obtain benzoxazine-PAMAM copolymer;

[0048] Step A4: Weigh out 25 parts by weight of mullite, 10 parts by weight of zirconia fiber, 25 parts by weight of silicon carbide, 40 parts by weight of mullite fiber, 10 parts by weight of aluminum dihydrogen phosphate, 10 parts by weight of benzoxazine-PAMAM copolymer, 20 parts by weight of silica powder, and 30 parts by weight of alumina powder, and set aside; wherein the zirconia fiber has a length of 2.1-3.0 mm and a diameter of 0.003-0.008 mm; the mullite fiber has a length of 3-5 mm and a diameter of 0.005-0.015 mm;

[0049] Step A5: Mix mullite, zirconium oxide fiber, silicon carbide, mullite fiber, aluminum dihydrogen phosphate, benzoxazine-PAMAM copolymer, silica powder, niobium-zirconium alloy powder and alumina powder to obtain a high-strength refractory castable based on mullite modification.

[0050] Comparative Example 2:

[0051] This comparative example illustrates the preparation process of mullite-modified high-strength refractory castable, including the following steps:

[0052] Step A1: 0.2 mol eugenol, 0.2 mol p-phenylenediamine, 119.31 g paraformaldehyde, 320 mL toluene, and 80 mL N,N-dimethylformamide were added to a three-necked flask equipped with a reflux condenser and a thermometer. Nitrogen gas was introduced for protection, and the mixture was refluxed at 105 °C for 5 h. After cooling to 26 °C, the mixture was washed three times with sodium hydroxide solution and then three times with deionized water. The organic phase was collected by separation, and toluene and N,N-dimethylformamide were removed by rotary evaporation. The mixture was then placed in a drying oven and vacuum dried at 40 °C for 16 h to obtain dienyl dibenzoxazine.

[0053] Step A2: Weigh out 25 parts by weight of mullite, 10 parts by weight of zirconium oxide fiber, 25 parts by weight of silicon carbide, 40 parts by weight of mullite fiber, 10 parts by weight of aluminum dihydrogen phosphate, 10 parts by weight of diene dibenzoxazine, 20 parts by weight of silica powder, 5 parts by weight of niobium-zirconium alloy powder, and 30 parts by weight of alumina powder, and set aside for later use; wherein, the zirconium oxide fiber has a length of 2.1-3.0 mm and a diameter of 0.003-0.008 mm; the mullite fiber has a length of 3-5 mm and a diameter of 0.005-0.015 mm; the niobium-zirconium alloy powder has a particle size of 0.015-0.053 mm; and the zirconium content in the niobium-zirconium alloy powder is 25%;

[0054] Step A3: Mix mullite, zirconium oxide fiber, silicon carbide, mullite fiber, aluminum dihydrogen phosphate, diene dibenzoxazine, silica powder, niobium zirconium alloy powder and alumina powder to obtain a high-strength refractory castable based on mullite modification.

[0055] Comparative Example 3:

[0056] This comparative example illustrates the preparation process of mullite-modified high-strength refractory castable, including the following steps:

[0057] Step A1: Add 0.045 mol N-methylpropyneamine and 300 mL methanol to a three-necked flask equipped with a thermometer, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically for 10 min, add 0.378 mol ethyl acrylate dropwise, controlling the dropwise addition time to 30 min, transfer to an oil bath and stir the reaction at 35 °C for 24 h, then distill under reduced pressure at 60 °C to obtain intermediate product 1;

[0058] Step A2: 94.4 mmol of intermediate 1 and 160 mL of methanol were added to a three-necked flask equipped with a thermometer. Nitrogen gas was introduced for protection. The mixture was then transferred to an ice-water bath and magnetically stirred for 10 min. 0.378 mol of ethyl acrylate was added dropwise over a time of 30 min. 80 mL of ethylenediamine-methanol solution was added over a time of 30 min. The mixture was then transferred to an oil bath and stirred at 35 °C for 24 h. The mixture was then distilled under reduced pressure at 60 °C. The product was washed five times with ethyl acetate and then distilled under reduced pressure for 3 h to obtain the propargylamine-PAMAM copolymer.

[0059] Step A3: Weigh out 25 parts by weight of mullite, 10 parts by weight of zirconium oxide fiber, 25 parts by weight of silicon carbide, 40 parts by weight of mullite fiber, 10 parts by weight of aluminum dihydrogen phosphate, 10 parts by weight of propargylamine-PAMAM copolymer, 20 parts by weight of silica powder, 5 parts by weight of niobium-zirconium alloy powder, and 30 parts by weight of alumina powder, and set aside for later use; wherein, the zirconium oxide fiber has a length of 2.1-3.0 mm and a diameter of 0.003-0.008 mm; the mullite fiber has a length of 3-5 mm and a diameter of 0.005-0.015 mm; the niobium-zirconium alloy powder has a particle size of 0.015-0.053 mm; and the zirconium content in the niobium-zirconium alloy powder is 25%;

[0060] Step A4: Mix mullite, zirconium oxide fiber, silicon carbide, mullite fiber, aluminum dihydrogen phosphate, propargylamine-PAMAM copolymer, silica powder, niobium-zirconium alloy powder and alumina powder to obtain a high-strength refractory castable based on mullite modification.

[0061] Performance testing

[0062] The refractory castables of Examples 1-3 and Comparative Examples 1-3 were subjected to abrasion tests according to "GB / T 18301-2012 Test Method for Abrasion Resistance of Refractory Materials at Room Temperature" and flexural strength tests according to "GB / T 3002-2017 Test Method for Flexural Strength of Refractory Materials at High Temperature". The test conditions were 110℃×24h, 1100℃×3h and 1350℃×3h, respectively, to obtain the abrasion amount and flexural strength.

[0063]

[0064] Referring to the table above, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the refractory castable prepared from benzoxazine-PAMAM copolymer and niobium-zirconium alloy powder has high flexural strength.

[0065] Based on the comparison between Example 3 and Comparative Example 1, it can be seen that the flexural strength of the refractory castable prepared from benzoxazine-PAMAM copolymer and niobium-zirconium alloy powder is higher than that of the refractory castable prepared from benzoxazine-PAMAM copolymer, indicating that the refractory castable prepared from benzoxazine-PAMAM copolymer and niobium-zirconium alloy powder has excellent flexural strength.

[0066] Based on the comparison between Example 3 and Comparative Example 2, it can be seen that the flexural strength of the refractory castable prepared from benzoxazine-PAMAM copolymer and niobium-zirconium alloy powder is higher than that of the refractory castable prepared from benzoxazine and niobium-zirconium alloy powder, indicating that the refractory castable prepared from benzoxazine-PAMAM copolymer and niobium-zirconium alloy powder has excellent flexural strength.

[0067] Based on the comparison between Example 3 and Comparative Example 3, it can be seen that the refractory castable prepared from benzoxazine-PAMAM copolymer and niobium-zirconium alloy powder has a higher flexural strength than the refractory castable prepared from propargylamine-PAMAM copolymer and niobium-zirconium alloy powder, indicating that the refractory castable prepared from benzoxazine-PAMAM copolymer and niobium-zirconium alloy powder has excellent flexural strength.

[0068] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0069] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. High-strength refractory castable based on mullite modification, characterized in that, Includes the following components by weight: 15-25 parts mullite, 5-10 parts zirconium oxide fiber, 15-25 parts silicon carbide, 30-40 parts mullite fiber, 5-10 parts aluminum dihydrogen phosphate, 5-10 parts benzoxazine-PAMAM copolymer, 10-20 parts silica powder, 3-5 parts niobium-zirconium alloy powder, and 20-30 parts alumina powder. The benzoxazine-PAMAM copolymer is prepared by the following steps: Step A1: Eugenol, p-phenylenediamine, paraformaldehyde, toluene, and N,N-dimethylformamide were added to a three-necked flask, nitrogen gas was introduced for protection, the reaction was refluxed, cooled, washed with sodium hydroxide solution, then washed with deionized water, the organic phase was collected by separation, toluene and N,N-dimethylformamide were removed by rotary evaporation, and dried to obtain dienyl dibenzoxazine; Step A2: Diethylamine and methanol were added to a three-necked flask, nitrogen gas was introduced for protection, the mixture was transferred to an ice-water bath and magnetically stirred, dienyl dibenzoxazine was added, the mixture was transferred to an oil bath and stirred at 25-35°C, and then distilled under reduced pressure at 60°C to obtain intermediate product 1. Step A3: Add intermediate product 1 and methanol to a three-necked flask, purge with nitrogen for protection, transfer to an ice-water bath and stir magnetically, add ethyl acrylate dropwise while controlling the addition time, add ethylenediamine-methanol solution while controlling the addition time, transfer to an oil bath and stir to react, distill under reduced pressure, wash with ethyl acetate, and distill under reduced pressure to obtain benzoxazine-PAMAM copolymer.

2. The mullite-modified high strength refractory castable according to claim 1, characterized in that, The ratio of eugenol, p-phenylenediamine, paraformaldehyde, toluene, and N,N-dimethylformamide used in step A1 is 0.1-0.2 mol: 0.1-0.2 mol: 57.66-119.31 g: 160-320 mL: 40-80 mL.

3. The mullite-modified high strength refractory castable according to claim 1, characterized in that, The molar concentration of the sodium hydroxide solution in step A1 is 0.5 mol / L; the CAS number of the paraformaldehyde is 30525-89-4.

4. The mullite-modified high strength refractory castable according to claim 1, characterized in that, The ratio of diethylamine, methanol, and diene dibenzoxazine used in step A2 is 0.015-0.045 mol: 100-300 mL: 0.05-0.15 mol.

5. The mullite-modified high strength refractory castable according to claim 1, characterized in that, The ratio of intermediate product 1, methanol, ethyl acrylate and ethylenediamine-methanol solution used in step A3 is 47.2-94.4 mmol: 80-160 mL: 0.189-0.378 mol: 40-80 mL.

6. The mullite-modified high strength refractory castable according to claim 1, characterized in that, In step A3, the ratio of ethylenediamine to methanol in the ethylenediamine-methanol solution is 0.7-1.4 mol: 40-80 mL.

7. A process for the preparation of high strength refractory castable based on mullite modification, characterized by, Includes the following steps: Step 1: Weigh out 15-25 parts by weight of mullite, 5-10 parts by weight of zirconium oxide fiber, 15-25 parts by weight of silicon carbide, 30-40 parts by weight of mullite fiber, 5-10 parts by weight of aluminum dihydrogen phosphate, 5-10 parts by weight of benzoxazine-PAMAM copolymer, 10-20 parts by weight of silica powder, 3-5 parts by weight of niobium-zirconium alloy powder, and 20-30 parts by weight of alumina powder, and set aside. The zirconium oxide fiber has a length of 2.1-3.0 mm and a diameter of 0.003-0.008 mm; the mullite fiber has a length of 3-5 mm and a diameter of 0.005-0.015 mm; the niobium-zirconium alloy powder has a particle size of 0.015-0.053 mm; and the zirconium content in the niobium-zirconium alloy powder is 25%. Step 2: Mix mullite, zirconium oxide fiber, silicon carbide, mullite fiber, aluminum dihydrogen phosphate, benzoxazine-PAMAM copolymer, silica powder, niobium-zirconium alloy powder and alumina powder to obtain a high-strength refractory castable based on mullite modification.