A boron-based antioxidant-containing carbon-containing refractory material and a method for producing the same

Abstract

The application belongs to the technical field of refractory materials, and particularly relates to a carbon-containing refractory material based on a boron-based antioxidant and a preparation method thereof. The carbon-containing refractory material based on the boron-based antioxidant comprises the following components in parts by weight: magnesia particles 60-70 parts, graphite 10-15 parts, a boron-based antioxidant 5-10 parts, silicon powder 1-2 parts, and a binding agent 5-8 parts. The preparation method comprises the following steps: S21, raw material pretreatment: screening the magnesia particles and drying the graphite; S22, batching: putting the magnesia particles, the graphite, the boron-based antioxidant, the silicon powder and the binding agent into a mixer and mixing for 30-60 minutes; S23, forming: forming the mixed material under a pressure of 100-200 MPa; and S24, heat treatment: drying the formed body, and then sintering at 800-1600 DEG C for 3-5 hours to obtain the carbon-containing refractory material based on the boron-based antioxidant. The prepared product has good performances of compressive strength, strength retention rate after thermal shock, 1800 DEG C oxidation weight loss rate and slag erosion resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of refractory materials, and particularly relates to a carbon-containing refractory material based on a boron-based antioxidant and a preparation method thereof. BACKGROUND

[0002] Carbon-containing refractory materials have been widely used in the high-temperature industries such as steel and non-ferrous metallurgy due to their good thermal shock resistance and slag corrosion resistance. Carbon-containing refractory materials are widely used in key parts of steelmaking equipment such as converters, electric furnaces, ladles and refining furnaces. The graphite introduced in these refractory materials not only improves the thermal shock resistance of the products, but also improves the anti-spalling property and slag corrosion resistance of the refractory materials. Common carbon-containing refractory materials mainly include MgO-C, Al2O3-C and MgO-CaO-C, etc. The emergence of these carbon-containing refractory materials plays an important role in the production and development of the steel industry. However, the carbon in carbon-containing refractory materials is easily oxidized at high temperatures, which leads to the destruction of the structure and the decline of the performance of the materials, thereby shortening the service life of the refractory materials and increasing the production cost.

[0003] Traditional antioxidants such as metal aluminum powder and silicon powder can improve the oxidation resistance of carbon-containing refractory materials to some extent, but they have some shortcomings. For example, metal aluminum powder is easily reacted with water vapor to generate hydrogen at high temperatures, which leads to the swelling and cracking of the material; the oxidation resistance effect of silicon powder is limited, and it is easy to form low-melting silicate phases at high temperatures, which reduces the high-temperature strength of the material.

[0004] Boron-based compounds have unique physical and chemical properties, and can form stable borate protective films at high temperatures to prevent the diffusion of oxygen to the inside of the material, thereby improving the oxidation resistance of the material. In addition, boron-based compounds can also improve the sintering performance and high-temperature strength of the material.

[0005] CN115745638B discloses a mullite and boron carbide light weight refractory material and a preparation method thereof. The technical solution is: the raw materials and their contents of the mullite-boron carbide light weight refractory material are: 45-77wt% of light weight mullite aggregate, 14-33wt% of boron carbide powder, 4-10wt% of hydrated alumina, and 5-12wt% of polystyrene balls; 0.1-0.5wt% of sodium tripolyphosphate and 5-10wt% of water are added to the raw materials. The preparation method of the mullite and boron carbide light weight refractory material is: first, the boron carbide, hydrated alumina and sodium tripolyphosphate are ball milled, dried to obtain a mixed powder. Then, the mixed powder, polystyrene balls, light weight mullite aggregate and water are stirred uniformly, cast into a shape, cured, dried, and then heated to 1300-1650℃ at a rate of 5-20℃ / min in a carbon-embedded atmosphere, and kept for 2-6h to obtain the mullite and boron carbide light weight refractory material. The process is simple, the cost is low, and the industrial production is easy. The product has small density, high strength and long service life. However, the performance of the prepared product still needs to be improved.

[0006] Therefore, it is of great practical significance to develop a new antioxidant to improve the antioxidant performance of carbon-containing refractory materials while maintaining other excellent properties of the materials. SUMMARY

[0007] To solve the above technical problems, the application provides a carbon-containing refractory material based on a boron-based antioxidant, which comprises the following components in parts by weight: 60-70 parts of magnesia particles, 10-15 parts of graphite, 5-10 parts of a boron-based antioxidant, 1-2 parts of silicon powder, and 5-8 parts of a binding agent. The silicon powder in the components can react with oxygen to form silicon dioxide at high temperatures, and the silicon dioxide reacts with other components to form a low-melting-point glass phase, filling the pores of the material and improving the density of the material. At the same time, the silicon powder can also improve the sintering performance of the material.

[0008] Further, the boron-based antioxidant is composed of 1-5 parts of nano boron carbide particles coated with boric acid, 1-4 parts of boron nitride-aluminum borate composite reinforcing phase, 1-2 parts of titanium boride, and 0-4 parts of titanium aluminum carbide. Titanium boride generates TiO2-B2O3 phase during sintering, which forms Ti-Si-C interface with Si to improve the corrosion resistance; titanium aluminum carbide introduces layered ceramic Ti3AlC2, which decomposes into TiC X / Al2O3 nanoparticles, repairing micro-cracks, enhancing product strength; boric acid coated nano boron carbide particles, between 250~400℃, boric acid melts to form a glass phase to seal pores, between 800~1200℃, boron carbide is oxidized to form B2O3, forming a dense boron aluminates, between 1400~1600℃, residual B4C in situ generates B2O3-Al2O3-SiC composite ceramic layer. Therefore, boron-based antioxidants can not only inhibit the oxidation of carbon, but also generate liquid phase material to coat carbon and fill pores, making the structure of refractory materials more dense, thereby significantly enhancing the high-temperature service performance and thermal shock resistance of carbon-containing refractory materials.

[0009] Further, the particle size of the magnesia particles is mixed by 3~5mm, 1~3mm and 0~1mm particles in a mass ratio of 1:1:1. Magnesia is a high-melting-point alkaline refractory raw material with good resistance to alkaline slag erosion. Its crystal structure is stable, which can provide the basic framework and high-temperature strength of the material. At the same time, at high temperature, magnesia can react with other components to form a solid solution or a composite mineral phase, further improving the performance of the material.

[0010] Further, the graphite is flake graphite. Graphite has good thermal conductivity and lubricity, which can improve the thermal shock resistance of the material, and as the core of the thermal conduction network, it can reduce the thermal expansion coefficient of the material. At the same time, graphite has high chemical stability and can resist slag erosion to some extent, but graphite is easily oxidized, so an antioxidant needs to be added for protection.

[0011] Further, the binder is boron-modified phenolic resin or phenolic resin. Phenolic resin can bond the components together at room temperature, giving the material certain forming strength. At high temperatures, phenolic resin will carbonize to form a carbon network, further enhancing the strength and oxidation resistance of the material. Boron-modified phenolic resin contains B-O-C bonds, which form B4C after carbonization to enhance the carbon network, making it a better choice.

[0012] Further, in the boron nitride-aluminum borate composite reinforcing phase, the mass ratio of boron nitride to aluminum borate is 1:1, and the two are pre-mixed to form an interwoven network by ball milling. The interwoven network of boron nitride-aluminum borate composite reinforcing phase can reduce cracking and bridge cracks.

[0013] Further, the preparation method of the boric acid coated nano boron carbide particles is:

[0014] S11. Add nano boron carbide to 3 times its mass of ethanol, ultrasonically disperse to obtain a mixed solution A;

[0015] S12. Atomizing and spraying 30wt% boric acid ethanol solution into the mixed solution A obtained in step S11 at a temperature of 58-62℃, the mass of the boric acid is 0.3-1 times of the mass of the boron carbide in step S11, to obtain mixed solution B;

[0016] S13. Vacuum drying the mixed solution B obtained in step S12 to obtain borate-coated nano boron carbide particles.

[0017] The application also provides a preparation method of the carbon-containing refractory material based on the boron-based antioxidant, comprising the following steps:

[0018] S21. Raw material pretreatment: screening the magnesia particles and drying the graphite;

[0019] S22. Blending: putting the magnesia particles, graphite, boron-based antioxidant, silicon powder and binder into a mixer and mixing for 30-60 minutes;

[0020] S23. Forming: forming the mixed material under a pressure of 100-200MPa;

[0021] S24. Heat treatment: drying the formed body at a temperature of 180-220℃ for 12-24 hours, and then sintering at a temperature of 800-1600℃ for 3-5 hours to obtain the carbon-containing refractory material based on the boron-based antioxidant.

[0022] Further, the sintering process adopts microwave gradient sintering at a frequency of 2.45GHz, the first stage: passing N2 protection, rapidly heating to 800℃, the binder is carbonized to form a porous carbon skeleton, sintering for 1h, the second stage: passing argon protection, heating to 1400℃ for sintering for 1.5h, promoting interface reaction, the third stage: sintering at 1600℃ for 0.5h, forming a surface densification structure. The microwave-assisted gradient sintering process accelerates the reaction by using microwave energy field to form a dense gradient structure and improve the performance of the product.

[0023] The preparation of the carbon-containing refractory material based on the boron-based antioxidant has the following advantages:

[0024] 1. Excellent antioxidant performance: the boron-based antioxidant can form a stable borate protective film at high temperature, effectively preventing the diffusion of oxygen into the material, significantly improving the antioxidant performance of the carbon-containing refractory material. Compared with traditional carbon-containing refractory materials, the thickness of the oxidation layer of the material of the application is significantly reduced under the same oxidation conditions.

[0025] 2. Good thermal shock resistance: the presence of graphite improves the thermal conductivity and thermal shock resistance of the material, and the synergistic effect of boron-based compounds and other additives further enhances the structural stability of the material, so that the material is not prone to cracking and peeling when the temperature changes sharply.

[0026] 3. Strong slag resistance: The high alkali slag erosion resistance of magnesia and the synergistic effect of boron-based compounds and additives enable the material to effectively resist the erosion of molten slag, prolonging the service life of the material. DETAILED DESCRIPTION

[0027] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clear and explicit, the following will be further described in detail in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0028] Example 1

[0029] A carbon-containing refractory based on boron-based antioxidant includes the following substances in parts by weight: 60 kg of magnesia particles, 12 kg of flake graphite, 6 kg of boron-based antioxidant, 2 kg of silicon powder, and 6 kg of phenolic resin.

[0030] The boron-based antioxidant is composed of 2 kg of boron acid-coated nano boron carbide particles, 3 kg of boron nitride-aluminum borate composite reinforcing phase, and 1 kg of titanium boride. In the boron nitride-aluminum borate composite reinforcing phase, the mass ratio of boron nitride to aluminum borate is 1:1, and the two are pre-mixed by ball milling to form an interwoven network. The preparation method of the boron acid-coated nano boron carbide particles is:

[0031] S11. Add nano boron carbide to 3 times its mass of ethanol and ultrasonically disperse to obtain a mixture A;

[0032] S12. Atomize and spray a 30wt% boric acid ethanol solution into the mixture A obtained in step S11 at a temperature of 58-62℃, the mass of the boric acid being 0.5 times the mass of the boron carbide in step S11, to obtain a mixture B;

[0033] S13. Vacuum dry the mixture B obtained in step S12 to obtain boron acid-coated nano boron carbide particles.

[0034] The particle size of the magnesia particles is composed of 2 kg of each of three specifications of magnesia with particle sizes of 3-5 mm, 1-3 mm, and 0-1 mm.

[0035] The above preparation method of the carbon-containing refractory based on boron-based antioxidant includes the following steps:

[0036] S21. Raw material pretreatment: screen the magnesia particles and dry the graphite;

[0037] S22. Batch mixing: put the magnesia particles, graphite, boron-based antioxidant, silicon powder, and binder into a mixer and mix for 40 minutes;

[0038] S23. Forming: the mixed material is formed under a pressure of 120 MPa;

[0039] S24. Heat treatment: the formed body is dried at 190-200℃ for 20 hours, and then sintered at 800-1600℃ for 4 hours to obtain the boron-based antioxidant-based carbon-containing refractory material.

[0040] Example 2

[0041] A boron-based antioxidant-based carbon-containing refractory material, comprising the following substances in parts by weight: magnesia particles 60 kg, flake graphite 12 kg, boron-based antioxidant 6 kg, silicon powder 2 kg, and phenolic resin 6 kg.

[0042] The boron-based antioxidant is composed of boron acid-coated nanometer boron carbide particles 2 kg, boron nitride-aluminum borate composite reinforcing phase 3 kg, titanium boride 1 kg, and titanium aluminum carbide 2 kg. In the boron nitride-aluminum borate composite reinforcing phase, the mass ratio of boron nitride to aluminum borate is 1:1, and the two are pre-mixed by ball milling to form an interwoven network. The preparation method of the boron acid-coated nanometer boron carbide particles is:

[0043] S11. Nanometer boron carbide is added to 3 times its mass of ethanol, and ultrasonic dispersion is performed to obtain a mixed solution A;

[0044] S12. At a temperature of 58-62℃, a 30wt% boric acid ethanol solution is atomized and sprayed into the mixed solution A obtained in step S11, and the mass of the boric acid is 0.5 times the mass of the boron carbide in step S11 to obtain a mixed solution B;

[0045] S13. The mixed solution B obtained in step S12 is vacuum dried to obtain boron acid-coated nanometer boron carbide particles.

[0046] The particle size of the magnesia particles is composed of 2 kg of each of three specifications of magnesia with particle sizes of 3-5 mm, 1-3 mm, and 0-1 mm.

[0047] The above-mentioned preparation method of the boron-based antioxidant-based carbon-containing refractory material comprises the following steps:

[0048] S21. Raw material pretreatment: the magnesia particles are screened, and the graphite is dried;

[0049] S22. Blending: the magnesia particles, graphite, boron-based antioxidant, silicon powder, and binder are placed in a mixer and mixed for 40 minutes;

[0050] S23. Forming: the mixed material is formed under a pressure of 120 MPa;

[0051] S24. Heat treatment: drying the shaped body at 190-200℃ for 20 hours, and then sintering at 800-1600℃ for 4 hours to obtain the carbon-containing refractory material based on the boron-based antioxidant.

[0052] Example 3

[0053] A carbon-containing refractory material based on a boron-based antioxidant, comprising the following substances in parts by weight: magnesia particles 60 kg, flake graphite 12 kg, boron-based antioxidant 6 kg, silicon powder 2 kg, boron-modified phenolic resin 6 kg.

[0054] The boron-based antioxidant is composed of boron acid-coated nanometer boron carbide particles 2 kg, boron nitride-aluminum borate composite reinforcing phase 3 kg, and titanium boride 1 kg. In the boron nitride-aluminum borate composite reinforcing phase, the mass ratio of boron nitride to aluminum borate is 1:1, and the two are pre-mixed by ball milling to form an interwoven network. The preparation method of the boron acid-coated nanometer boron carbide particles is:

[0055] S11. Add nanometer boron carbide to 3 times its mass of ethanol, and ultrasonically disperse to obtain a mixed solution A;

[0056] S12. Atomize and spray a 30wt% boric acid ethanol solution into the mixed solution A obtained in step S11 at a temperature of 58-62℃, the mass of the boric acid being 0.5 times the mass of the boron carbide in step S11, to obtain a mixed solution B;

[0057] S13. Vacuum dry the mixed solution B obtained in step S12 to obtain boron acid-coated nanometer boron carbide particles.

[0058] The particle size of the magnesia particles is composed of 2 kg of each of three specifications of magnesia with particle sizes of 3-5 mm, 1-3 mm, and 0-1 mm.

[0059] The above method for preparing a carbon-containing refractory material based on a boron-based antioxidant comprises the following steps:

[0060] S21. Raw material pretreatment: screen the magnesia particles and dry the graphite;

[0061] S22. Blending: place the magnesia particles, graphite, boron-based antioxidant, silicon powder, and binder into a mixer and mix for 40 minutes;

[0062] S23. Shaping: shape the mixed material under a pressure of 120 MPa;

[0063] S24. Heat treatment: dry the shaped body at 190-200℃ for 20 hours, and then sinter at 800-1600℃ for 4 hours to obtain the carbon-containing refractory material based on the boron-based antioxidant.

[0064] Example 4

[0065] A carbon-containing refractory based on boron-based antioxidant, comprising the following substances in parts by weight: magnesia particles 60 kg, flake graphite 12 kg, boron-based antioxidant 6 kg, silicon powder 2 kg, phenolic resin 6 kg.

[0066] The boron-based antioxidant is composed of boron acid-coated nanometer boron carbide particles 2 kg, boron nitride-aluminum borate composite reinforcing phase 3 kg, and titanium boride 1 kg. In the boron nitride-aluminum borate composite reinforcing phase, the mass ratio of boron nitride to aluminum borate is 1:1, and the two are pre-mixed to form an interwoven network by ball milling. The preparation method of the boron acid-coated nanometer boron carbide particles is:

[0067] S11. Add nanometer boron carbide to its mass 3 times of ethanol, ultrasonic dispersion, to obtain a mixed solution A;

[0068] S12. Atomize and spray a 30wt% boric acid ethanol solution into the mixed solution A obtained in step S11 at a temperature of 58-62℃, the mass of boric acid is 0.5 times the mass of boron carbide in step S11, to obtain a mixed solution B;

[0069] S13. Vacuum dry the mixed solution B obtained in step S12 to obtain boron acid-coated nanometer boron carbide particles.

[0070] The particle size of the magnesia particles is composed of 2 kg of each of three specifications of magnesia with particle sizes of 3-5 mm, 1-3 mm, and 0-1 mm.

[0071] The preparation method of the above-mentioned carbon-containing refractory based on boron-based antioxidant, comprising the following steps:

[0072] S21. Raw material pretreatment: screen the magnesia particles and dry the graphite;

[0073] S22. Batch mixing: put the magnesia particles, graphite, boron-based antioxidant, silicon powder, and binder into a mixer and mix for 40 minutes;

[0074] S23. Forming: form the mixed material under a pressure of 120 MPa;

[0075] S24. Heat treatment: dry the formed body at a temperature of 190-200℃ for 20 hours, and then sinter at a temperature of 800-1600℃ for 3 hours to obtain the carbon-containing refractory based on boron-based antioxidant.

[0076] The sintering process adopts microwave gradient sintering at a frequency of 2.45 GHz, the first stage: passing through N2 protection, rapidly heating to 800 DEG C, combining binder carbonization to form a porous carbon skeleton, sintering for 1 h, the second stage: passing through argon protection, heating to 1400 DEG C and sintering for 1.5 h, promoting interface reaction, the third stage: sintering at 1600 DEG C for 0.5 h, forming a surface layer densification structure.

[0077] Comparative Example 1

[0078] In Example 1, replace the boron-based antioxidant 6 kg with aluminum powder 6 kg, and the rest is the same as Example 1, which will not be repeated.

[0079] Comparative Example 2

[0080] In Example 1, remove the boron nitride-aluminum borate composite reinforcing phase component, and the rest is the same as Example 1, which will not be repeated.

[0081] The boron-based antioxidant-based carbon-containing refractory materials prepared in the above examples and comparative examples are shown in Table 1.

[0082] Table 1 test results

[0083] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Compressive strength, MPa 135 136 135 140 120 130 Strength retention rate after thermal shock, % 92.1 92.5 92.1 93.5 88.2 91.3 Oxidation loss rate at 1800°C (24 h), % 0.98 0.96 0.97 0.89 1.85 1.08 Slag resistance rate, % 1.8 1.6 1.7 1.5 3.2 1.9

[0084] As can be seen from the above table data, the boron-based antioxidant-based carbon-containing refractory materials prepared in Examples 1-4 have good performance in compression strength, strength retention rate after thermal shock, oxidation loss rate at 1800 DEG C, and slag erosion resistance. The comparison of data between Example 1 and Example 2 shows that the addition of titanium aluminum carbide significantly improves the overall performance of the product. The comparison of data between Example 1 and Example 4 shows that the product prepared by step sintering has better performance. The data of Comparative Example 1 shows that the boron-based antioxidant prepared by the present application has significant technical advantages and the performance of the prepared product is comprehensively improved. The data of Comparative Example 2 shows that the boron nitride-aluminum borate composite reinforcing phase can improve the performance of the product.

Claims

1. A carbon-containing refractory material based on boron-based antioxidant, characterized in that, The boron-based antioxidant is composed of 1-5 parts of nano boron carbide particles coated with boric acid, 1-4 parts of boron nitride-aluminum borate composite reinforcing phase, 1-2 parts of titanium boride and 0-4 parts of titanium aluminum carbide.

2. The boron-based antioxidant-containing carbon-containing refractory material of claim 1, wherein, The particle size of the magnesia particles is obtained by mixing particles of 3-5 mm, 1-3 mm and 0-1 mm in a mass ratio of 1:1:

1.

3. The boron-based antioxidant-containing carbon-containing refractory material of claim 1, wherein, The graphite is flake graphite.

4. The boron-based antioxidant-containing carbon-containing refractory material of claim 1, wherein, The binder is boron-modified phenolic resin or phenolic resin.

5. The boron-based antioxidant-containing carbon-containing refractory material of claim 1, wherein, In the boron nitride-aluminum borate composite reinforcing phase, the mass ratio of boron nitride to aluminum borate is 1:1, and the two are pre-mixed by ball milling to form an interwoven network.

6. The boron-based antioxidant-containing carbon-containing refractory material of claim 1, wherein, The preparation method of the nano boron carbide particles coated with boric acid is: S11. Add nano boron carbide to 3 times its mass of ethanol and ultrasonically disperse to obtain a mixture A; S12. Atomize and spray 30wt% boric acid ethanol solution into the mixture A obtained in step S11 at a temperature of 58-62℃, the mass of the boric acid being 0.3-1 times the mass of the boron carbide in step S11, to obtain a mixture B; S13. Vacuum dry the mixture B obtained in step S12 to obtain nano boron carbide particles coated with boric acid.

7. A method for producing a boron-based antioxidant-containing carbon-containing refractory material according to any one of claims 1 to 6, characterized by, The method comprises the following steps: S21. Raw material pretreatment: screen the magnesia particles and dry the graphite; S22. Batch mixing: put the magnesia particles, graphite, boron-based antioxidant, silicon powder and binder into a mixer and mix for 30-60 minutes; S23. Forming: form the mixed material under a pressure of 100-200 MPa; S24. Heat treatment: dry the formed body at a temperature of 180-220℃ for 12-24 hours, and then sinter at a temperature of 800-1600℃ for 3-5 hours to obtain boron-based antioxidant-containing carbon-containing refractory material.

8. The method for producing a boron-based antioxidant-containing carbon-containing refractory material according to claim 7, characterized by, The sintering process adopts microwave gradient sintering at a frequency of 2.45 GHz, the first stage: pass N2 protection, rapidly heat to 800℃, the binder is carbonized to form a porous carbon skeleton, sinter for 1h, the second stage: pass argon protection, heat to 1400℃ for 1.5h, promote interface reaction, the third stage: 1600℃ sintering for 0.5h, form a surface densification structure.