Nitrogen-containing silicon-magnesium-based low-carbon refractory with strong interfacial bonding and method for preparing same

Abstract

The application relates to a strong-interface-bonding low-carbon refractory material based on nitrogen-containing silicon magnesium nitride and a preparation method thereof. The technical scheme is as follows: aluminum powder, silicon magnesium nitride powder and fused white corundum fine powder are mixed, polyvinyl butyral is added, stirring is conducted, the mixture is placed in a tube furnace, heat preservation is conducted under the condition of a nitrogen atmosphere and 600-700 DEG C, and a composite powder is prepared. Phenolic resin is added into alcohol and stirred to obtain a mixture I, the composite powder is added into the mixture I in 1-4 times, ultrasonic dispersion is conducted, and a mixture II is obtained. Then, under stirring, fused white corundum particles, the mixture II, flake graphite and aluminum powder are sequentially added, stirring is conducted, compression molding is conducted, and solidification is conducted; after solidification, the product is placed in a high-temperature tube furnace, heat preservation is conducted at 1200-1500 DEG C under a nitrogen atmosphere, cooling is conducted to 800-1100 DEG C, heat preservation is conducted, and the strong-interface-bonding low-carbon refractory material based on nitrogen-containing silicon magnesium nitride is prepared. The application has the advantages of simple process, short production period and low synthesis temperature, and the prepared product has the advantages of uniform ceramic phase distribution, high interface bonding strength and excellent mechanical properties.

Description

Technical Field

[0001] This invention belongs to the technical field of low-carbon refractory materials. Specifically, it relates to low-carbon refractory materials with strong interfacial bonding based on magnesium silicon nitride and their preparation methods. Background Technology

[0002] In recent years, the urgent requirements of clean steelmaking and a low-carbon economy have led to an increased demand for low / ultra-low carbon refractories. The reduction in carbon content prevents carbon-bonded refractories from forming a carbon network, inevitably weakening their properties. Replacing carbon bonding with ceramic bonding in the microstructure design of refractory materials can effectively solve the problem of decreased mechanical properties caused by low carbon content. However, in-situ generation of ceramic bonding in low-carbon refractories suffers from low bonding strength, uneven distribution, and difficulty in industrial production, thus limiting the application areas of low-carbon refractories.

[0003] Liu et al. (ZLLiu, CJDeng, C.Yu, et al. Improving the anti-oxidation and water wettability of graphite through the design of coating structure for the preparation of Al2O3–SiC–C castables[J], Ceram.Int.49(2023)29104–29113) pointed out in their research that the use of metal additives (Al, Si, Mg, Al-Si, Al-Mg) during heat treatment to react with resin pyrolysis gases and the ambient gas phase to generate in-situ ceramic phases with different morphologies enhances the performance of the material. However, the metal additives are affected by the temperature gradient of the material during heat treatment and transform into Al. (l) Mg (g) Si (l) SiO (g) The change in phases leads to inhomogeneity of the in-situ ceramic phase, which affects the mechanical properties of low-carbon refractory materials.

[0004] The patented technology, "Low-carbon magnesium-carbon refractory material with added silicon-magnesium nitride powder and its preparation method" (CN 110143808A), describes a technology that incorporates silicon-magnesium nitride into low-carbon magnesium-carbon refractory materials, resulting in excellent oxidation resistance and thermal shock resistance. However, the low-carbon refractory materials prepared by this technology do not form a strongly interfacially bonded ceramic phase, therefore the mechanical properties of the low-carbon refractory materials are not improved.

[0005] Liu et al. (GF. Liu, N. Liao, M. Nath, et al. Optimized mechanical properties and oxidation resistance of low carbon Al2O3–C refractories through Ti3AlC2 addition[J], J. Eur. Ceram. Soc. 41(2021) 2948–2957.) pointed out in their research that Ti3AlC2 helps to reconstruct the ceramic phase of low carbon refractories, thereby improving the mechanical properties of low carbon refractories. However, this technology requires high temperatures, involves complicated processes, has a long production cycle, and requires large equipment investment, making it difficult to industrialize the production of low carbon refractories. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of existing technologies and provides a method for preparing a strong interfacial bond low-carbon refractory material based on magnesium nitride silicon, which is simple to process, has a short production cycle, low synthesis temperature, and is easy to industrialize. The prepared product has a uniform ceramic phase distribution, high interfacial bond strength, and excellent mechanical properties.

[0007] To achieve the above objectives, the specific steps of the technical solution adopted by the present invention are as follows:

[0008] Step 1: Mass fraction of raw materials and coating agent in the strong interfacial bond low-carbon refractory material:

[0009] The raw materials are 40-55 wt% fused white corundum particles, 25-50 wt% fused white corundum fine powder, 2-4 wt% flake graphite, 4-6 wt% phenolic resin, 3-5 wt% aluminum powder and 1-5 wt% magnesium silicon nitride powder, and 3-6 wt% polyvinyl butyral is added as a coating agent. The raw materials and the coating agent are weighed and mixed according to their respective mass fractions.

[0010] Step 2: The preparation method of the strong interfacial bond low-carbon refractory material is carried out according to the mass fraction described in Step 1, following these steps:

[0011] Step 2.1: First, mix the aluminum powder, the silicon nitride magnesium powder and the fused white corundum fine powder, stir for 1-4 hours, then add the polyvinyl butyral and stir for 2-5 hours; then place it in a high-temperature tube furnace and keep it at 600-700℃ for 2-5 hours under a nitrogen atmosphere to obtain the composite powder.

[0012] Step 2.2: Add the phenolic resin to alcohol, stir and dilute to obtain mixture I; then add the composite powder to mixture I in 1 to 4 portions, and disperse by ultrasonication to obtain mixture II.

[0013] Step 2.3: Stir the fused white corundum particles in a mixer for 20-30 minutes, then add mixture II to the mixer and stir for 1-4 hours. Then add the flake graphite and the aluminum powder and stir for 3-6 hours to obtain mixture III.

[0014] Step 2.4: The mixture III is pressed into shape under 170-200 MPa and cured at 200-220°C for 24-48 hours. Then it is placed in a high-temperature tube furnace and heated to 1200-1500°C under a nitrogen atmosphere for 2-5 hours. Then it is cooled to 800-1100°C and held for 1-4 hours. The furnace is then cooled to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride.

[0015] The fused white fused alumina particles have an Al2O3 content ≥ 98 wt% and a particle size of 1–3 mm.

[0016] The Al2O3 content of the fused white corundum fine powder is ≥98wt%; the particle size of the fused white corundum fine powder is ≥0.045mm.

[0017] The carbon content of the flake graphite is ≥98wt%; the particle size of the flake graphite is ≥0.045mm.

[0018] The MgSiN2 content of the silicon magnesium nitride powder is ≥98wt%; the particle size of the silicon magnesium nitride powder is ≥100nm.

[0019] The aluminum powder has an Al content ≥ 98 wt% and a particle size ≥ 0.045 mm.

[0020] The resin is a thermosetting phenolic resin or a thermoplastic phenolic resin.

[0021] The polyvinyl butyral content in the polyvinyl alcohol is 10-15 wt%.

[0022] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0023] This invention involves mixing aluminum powder, magnesium silicon nitride powder, and fine fused white corundum powder, adding polyvinyl butyral, and holding the mixture at 600–700°C under a nitrogen atmosphere to obtain a composite powder. The composite powder is then added to a solution of phenolic resin and alcohol. Under stirring, fused white corundum particles, mixture II, flake graphite, and aluminum powder are added sequentially, stirred, pressed into shape, and cured. The mixture is then placed in a high-temperature tube furnace under a nitrogen atmosphere, heated to 1200–1500°C and held, then cooled to 800–1100°C and held, to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride. This invention features a simple process, short production cycle, low synthesis temperature, and ease of industrial production.

[0024] In this invention, the essence of MgSiN2 promoting the growth of ceramic phases in low-carbon refractory materials lies in utilizing its phase remodeling characteristics. With the increase of Mg in the system... (g) The gradual accumulation of Mg leads to an increase in its partial pressure, which then diffuses outward into the product under high temperature and concentration gradient. This process... (g) The outward diffusion of gas inhibits the entry of N2, thus significantly reducing the N2 partial pressure inside the sample. This decrease in N2 partial pressure promotes the complete phase reconstruction of MgSiN2, forming Mg. (g) Mg formed with Si3N4 (g) The ceramic phase diffuses into the matrix inside the sample through cracks or pores. At this point, the phase transformation of the ceramic phase is only affected by Mg. (g) The control of this process promotes the uniform distribution of the in-situ ceramic phase inside the low-carbon refractory material with strong interfacial bonding based on magnesium nitride-containing silicon.

[0025] This invention utilizes Mg ions with small ionic radii to enter tetrahedral or octahedral sites in the AlN polymorphism, enabling Mg to... 2+ Replace Al 3+ Mg-containing AlN polymorphs can be formed. These polymorphs begin to form at 1200–1300 °C, then react with Si3N4 and Al2O3 to generate plate-like Mg-Sialon and Mg-Sialon / Al2O3. This growth method enhances the interfacial bonding strength between Mg-Sialon and Al2O3.

[0026] This invention utilizes a uniformly distributed, strongly interfacially bonded Mg-Sialon / Al2O3 ceramic phase to enhance the connection between aggregate and matrix within low-carbon refractory materials, thereby effectively improving the mechanical properties of the finished product. The prepared low-carbon refractory material based on magnesium silicon nitride with a strong interfacial bond was tested and found to have a room-temperature compressive strength of 160–177 MPa and a room-temperature flexural strength of 30–35 MPa.

[0027] Therefore, the present invention has the characteristics of simple process, short production cycle, low synthesis temperature and easy industrial production. The ceramic phase of the prepared low carbon refractory material based on silicon magnesium nitride with strong interfacial bonding is uniformly distributed, has high interfacial bonding strength and excellent mechanical properties. Attached Figure Description

[0028] Figure 1 The XRD pattern of a low-carbon refractory material with strong interfacial bonding based on magnesium nitride silicon was prepared according to the present invention.

[0029] Figure 2 for Figure 1 The image shown is a SEM image of a low-carbon refractory material with strong interfacial bonding based on magnesium nitride-containing silicon. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of protection thereof.

[0031] A low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride and its preparation method. The preparation method described in this specific embodiment is as follows:

[0032] Step 1: Mass fraction of raw materials and coating agent in the strong interfacial bond low-carbon refractory material:

[0033] The raw materials are 40-55 wt% fused white corundum particles, 25-50 wt% fused white corundum fine powder, 2-4 wt% flake graphite, 4-6 wt% phenolic resin, 3-5 wt% aluminum powder and 1-5 wt% magnesium silicon nitride powder, and 3-6 wt% polyvinyl butyral is added as a coating agent. The raw materials and the coating agent are weighed and mixed according to their respective mass fractions.

[0034] Step 2: The preparation method of the strong interfacial bond low-carbon refractory material is carried out according to the mass fraction described in Step 1, following these steps:

[0035] Step 2.1: First, mix the aluminum powder, the silicon nitride magnesium powder and the fused white corundum fine powder, stir for 1-4 hours, then add the polyvinyl butyral and stir for 2-5 hours; then place it in a high-temperature tube furnace and keep it at 600-700℃ for 2-5 hours under a nitrogen atmosphere to obtain the composite powder.

[0036] Step 2.2: Add the phenolic resin to alcohol, stir and dilute to obtain mixture I; then add the composite powder to mixture I in 1 to 4 portions, and disperse by ultrasonication to obtain mixture II.

[0037] Step 2.3: Stir the fused white corundum particles in a mixer for 20-30 minutes, then add mixture II to the mixer and stir for 1-4 hours. Then add the flake graphite and the aluminum powder and stir for 3-6 hours to obtain mixture III.

[0038] Step 2.4: The mixture III is pressed into shape under 170-200 MPa and cured at 200-220°C for 24-48 hours. Then it is placed in a high-temperature tube furnace and heated to 1200-1500°C under a nitrogen atmosphere for 2-5 hours. Then it is cooled to 800-1100°C and held for 1-4 hours. The furnace is then cooled to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride.

[0039] The polyvinyl butyral content in the polyvinyl alcohol is 10-15 wt%.

[0040] In this specific implementation:

[0041] The fused white fused alumina particles have an Al2O3 content ≥ 98 wt% and a particle size of 1–3 mm.

[0042] The Al2O3 content of the fused white corundum fine powder is ≥98wt%; the particle size of the fused white corundum fine powder is ≥0.045mm.

[0043] The carbon content of the flake graphite is ≥98wt%; the particle size of the flake graphite is ≥0.045mm.

[0044] The MgSiN2 content of the silicon magnesium nitride powder is ≥98wt%; the particle size of the silicon magnesium nitride powder is ≥100nm.

[0045] The aluminum powder has an Al content ≥ 98 wt% and a particle size ≥ 0.045 mm.

[0046] The resin is a thermosetting phenolic resin or a thermoplastic phenolic resin.

[0047] The details will not be repeated in the examples.

[0048] Example 1

[0049] A low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride and its preparation method. The preparation method described in this embodiment is as follows:

[0050] Step 1: Mass fraction of raw materials and coating agent in the strong interfacial bond low-carbon refractory material:

[0051] The raw materials are 40 wt% fused white corundum particles, 50 wt% fused white corundum fine powder, 2 wt% flake graphite, 4 wt% phenolic resin, 3 wt% aluminum powder and 1 wt% magnesium silicon nitride powder, and 3 wt% polyvinyl butyral is added as a coating agent. The raw materials and the coating agent are weighed and mixed according to their respective mass fractions.

[0052] Step 2: The preparation method of the strong interfacial bond low-carbon refractory material is carried out according to the mass fraction described in Step 1, following these steps:

[0053] Step 2.1: First, mix the aluminum powder, the silicon nitride magnesium powder and the fused white corundum fine powder, stir for 1 hour, then add the polyvinyl butyral and stir for 2 hours; then place it in a high-temperature tube furnace and keep it at 600°C for 2 hours under a nitrogen atmosphere to obtain the composite powder.

[0054] Step 2.2: Add the phenolic resin to alcohol, stir and dilute to obtain mixture I; then add the composite powder to mixture I in one step, and disperse by ultrasonication to obtain mixture II.

[0055] Step 2.3: Stir the fused white corundum particles in a mixer for 20 minutes, then add mixture II to the mixer and stir for 1 hour. Then add the flake graphite and the aluminum powder and stir for 3 hours to obtain mixture III.

[0056] Step 2.4: The mixture III is pressed into shape at 170 MPa and cured at 200°C for 24 hours. Then it is placed in a high-temperature tube furnace and heated to 1200°C under a nitrogen atmosphere. The temperature is held for 2 hours, then cooled to 800°C and held for 1 hour. The mixture is then cooled with the furnace to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride.

[0057] The polyvinyl butyral content in the polyvinyl alcohol is 10-15 wt%.

[0058] The low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride prepared in this embodiment was tested and found to have a compressive strength of 160 MPa at room temperature and a flexural strength of 30 MPa at room temperature.

[0059] Example 2

[0060] A low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride and its preparation method. The preparation method described in this embodiment is as follows:

[0061] Step 1: Mass fraction of raw materials and coating agent in the strong interfacial bond low-carbon refractory material:

[0062] The raw materials are 45 wt% fused white corundum particles, 41.9 wt% fused white corundum fine powder, 2.7 wt% flake graphite, 4.7 wt% phenolic resin, 3.7 wt% aluminum powder and 2 wt% magnesium silicon nitride powder, and 4 wt% polyvinyl butyral is added as a coating agent. The raw materials and the coating agent are weighed and mixed according to their respective mass fractions.

[0063] Step 2: The preparation method of the strong interfacial bond low-carbon refractory material is carried out according to the mass fraction described in Step 1, following these steps:

[0064] Step 2.1: First, mix the aluminum powder, the silicon nitride magnesium powder and the fused white corundum fine powder, stir for 2 hours, then add the polyvinyl butyral and stir for 3 hours; then place it in a high-temperature tube furnace and keep it at 630°C for 3 hours under a nitrogen atmosphere to obtain the composite powder.

[0065] Step 2.2: Add the phenolic resin to alcohol, stir and dilute to obtain mixture I; then add the composite powder to mixture I in two portions, and disperse by ultrasonication to obtain mixture II.

[0066] Step 2.3: Stir the fused white corundum particles in a mixer for 23 minutes, then add mixture II to the mixer and stir for 2 hours. Then add the flake graphite and the aluminum powder and stir for 4 hours to obtain mixture III.

[0067] Step 2.4: The mixture III is pressed into shape at 180 MPa and cured at 205°C for 32 hours. Then it is placed in a high-temperature tube furnace and heated to 1300°C under a nitrogen atmosphere. The temperature is held for 3 hours, then cooled to 900°C and held for 2 hours. The mixture is then cooled with the furnace to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride.

[0068] The polyvinyl butyral content in the polyvinyl alcohol is 10-15 wt%.

[0069] The low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride prepared in this embodiment was tested and found to have a compressive strength of 168 MPa at room temperature and a flexural strength of 32 MPa at room temperature.

[0070] Example 3

[0071] A low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride and its preparation method. The preparation method described in this embodiment is as follows:

[0072] Step 1: Mass fraction of raw materials and coating agent in the strong interfacial bond low-carbon refractory material:

[0073] The raw materials are 50 wt% fused white corundum particles, 33.8 wt% fused white corundum fine powder, 3.4 wt% flake graphite, 5.4 wt% phenolic resin, 4.4 wt% aluminum powder and 3 wt% magnesium silicon nitride powder, and 5 wt% polyvinyl butyral is added as a coating agent. The raw materials and the coating agent are weighed and mixed according to their respective mass fractions.

[0074] Step 2: The preparation method of the strong interfacial bond low-carbon refractory material is carried out according to the mass fraction described in Step 1, following these steps:

[0075] Step 2.1: First, mix the aluminum powder, the silicon nitride magnesium powder and the fused white corundum fine powder, stir for 3 hours, then add the polyvinyl butyral and stir for 4 hours; then place it in a high-temperature tube furnace and keep it at 660°C for 4 hours under a nitrogen atmosphere to obtain the composite powder.

[0076] Step 2.2: Add the phenolic resin to alcohol, stir and dilute to obtain mixture I; then add the composite powder to mixture I in 3 portions, and disperse by ultrasonication to obtain mixture II.

[0077] Step 2.3: Stir the fused white corundum particles in a mixer for 26 minutes, then add mixture II to the mixer and stir for 3 hours. Then add the flake graphite and the aluminum powder and stir for 5 hours to obtain mixture III.

[0078] Step 2.4: The mixture III is pressed into shape at 190 MPa and cured at 210°C for 40 h. Then it is placed in a high-temperature tube furnace and heated to 1400°C under a nitrogen atmosphere. The temperature is held for 4 h, then cooled to 1000°C and held for 3 h. The mixture is then cooled with the furnace to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride.

[0079] The polyvinyl butyral content in the polyvinyl alcohol is 10-15 wt%.

[0080] The low-carbon refractory material with strong interfacial bonding based on magnesium nitride prepared in this embodiment was tested and found to have a compressive strength of 170 MPa at room temperature and a flexural strength of 33 MPa at room temperature.

[0081] Example 4

[0082] A low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride and its preparation method. The preparation method described in this embodiment is as follows:

[0083] Step 1: Mass fraction of raw materials and coating agent in the strong interfacial bond low-carbon refractory material:

[0084] The raw materials are 55 wt% fused white corundum particles, 25 wt% fused white corundum fine powder, 4 wt% flake graphite, 6 wt% phenolic resin, 5 wt% aluminum powder and 5 wt% magnesium silicon nitride powder, and 6 wt% polyvinyl butyral is added as a coating agent. The raw materials and the coating agent are weighed and mixed according to their respective mass fractions.

[0085] Step 2: The preparation method of the strong interfacial bond low-carbon refractory material is carried out according to the mass fraction described in Step 1, following these steps:

[0086] Step 2.1: First, mix the aluminum powder, the silicon nitride magnesium powder and the fused white corundum fine powder, stir for 4 hours, then add the polyvinyl butyral and stir for 5 hours; then place it in a high-temperature tube furnace and keep it at 700°C for 5 hours under a nitrogen atmosphere to obtain the composite powder.

[0087] Step 2.2: Add the phenolic resin to alcohol, stir and dilute to obtain mixture I; then add the composite powder to mixture I in 4 portions, and disperse by ultrasonication to obtain mixture II.

[0088] Step 2.3: Stir the fused white corundum particles in a mixer for 30 minutes, then add mixture II to the mixer and stir for 4 hours. Then add the flake graphite and the aluminum powder and stir for 6 hours to obtain mixture III.

[0089] Step 2.4: The mixture III is pressed into shape under 200 MPa and cured at 220°C for 48 hours. Then it is placed in a high-temperature tube furnace and heated to 1500°C under a nitrogen atmosphere for 5 hours. Then it is cooled to 1100°C and held for 4 hours. The furnace is then cooled to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride.

[0090] The polyvinyl butyral content in the polyvinyl alcohol is 10-15 wt%.

[0091] The low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride prepared in this embodiment was tested and found to have a compressive strength of 177 MPa at room temperature and a flexural strength of 35 MPa at room temperature.

[0092] Compared with the prior art, the specific implementation method has the following positive effects:

[0093] This invention involves mixing aluminum powder, magnesium silicon nitride powder, and fine fused white corundum powder, adding polyvinyl butyral, and holding the mixture at 600–700°C under a nitrogen atmosphere to obtain a composite powder. The composite powder is then added to a solution of phenolic resin and alcohol. Under stirring, fused white corundum particles, mixture II, flake graphite, and aluminum powder are added sequentially, stirred, pressed into shape, and cured. The mixture is then placed in a high-temperature tube furnace under a nitrogen atmosphere, heated to 1200–1500°C and held, then cooled to 800–1100°C and held, to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride. This invention features a simple process, short production cycle, low synthesis temperature, and ease of industrial production.

[0094] In this invention, the essence of MgSiN2 promoting the growth of ceramic phases in low-carbon refractory materials lies in utilizing its phase remodeling characteristics. With the increase of Mg in the system... (g) The gradual accumulation of Mg leads to an increase in its partial pressure, which then diffuses outward into the product under high temperature and concentration gradient. This process... (g) The outward diffusion of gas inhibits the entry of N2, thus significantly reducing the N2 partial pressure inside the sample. This decrease in N2 partial pressure promotes the complete phase reconstruction of MgSiN2, forming Mg. (g) Mg formed with Si3N4 (g) The ceramic phase diffuses into the matrix inside the sample through cracks or pores. At this point, the phase transformation of the ceramic phase is only affected by Mg. (g) The control of this process promotes the uniform distribution of the in-situ ceramic phase within the low-carbon refractory material based on strong interfacial bonding of silicon-magnesium nitride.

[0095] This invention utilizes Mg ions with small ionic radii to enter tetrahedral or octahedral sites in the AlN polymorphism, enabling Mg to... 2+ Replace Al 3+ Mg-containing AlN polymorphs can be formed. The Mg-containing AlN polymorphs begin to form at 1200–1300℃, and then react with Si3N4 and Al2O3 to generate plate-like Mg-Sialon and Mg-Sialon / Al2O3. This growth method improves the interfacial bonding strength between Mg-Sialon and Al2O3. The low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride prepared by this invention is shown in the attached figure. Figure 1 This is a SEM image of the low-carbon refractory material with strong interfacial bonding based on magnesium nitride-containing silicon nitride prepared in Example 4 of this paper. Figure 2 for Figure 1 The image shown is a SEM image of a low-carbon refractory material with strong interfacial bonding based on magnesium nitride-containing silicon. From... Figure 1 It can be seen that magnesium silicon nitride underwent phase reconstruction in low-carbon refractory materials, generating Mg-Sialon and MgAl2O4; from Figure 2It can be seen that lamellar Mg-Sialon and granular MgAl2O4 are formed on the surface of Al2O3 aggregate and in the matrix; this indicates that nano-MgSiN2 helps promote the growth of lamellar Mg-Sialon and granular MgAl2O4 in the aggregate and matrix. This ceramic phase growth mode changes the surface roughness of Al2O3 aggregate and increases the friction between aggregates; at the same time, the interlocking structure of the ceramic phase enhances the inter-matrix bonding strength. This synergistic effect of the ceramic phase folding structure is beneficial to the improvement of material performance.

[0096] This invention utilizes a uniformly distributed, strongly interfacially bonded Mg-Sialon / Al2O3 ceramic phase to enhance the connection between the aggregate and matrix within the low-carbon refractory material, thereby effectively improving the mechanical properties of the material. The prepared low-carbon refractory material based on magnesium silicon nitride with a strong interfacial bond was tested and found to have a room-temperature compressive strength of 160–177 MPa and a room-temperature flexural strength of 30–35 MPa.

[0097] Therefore, the present invention has the characteristics of simple process, short production cycle, low synthesis temperature and easy industrial production. The prepared products have uniform ceramic phase distribution, high interfacial bonding strength and excellent mechanical properties.

Claims

1. A method for preparing a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride, characterized in that... The preparation method of the strong interfacial bonded low-carbon refractory material is as follows: Step 1: Mass fraction of raw materials and coating agent in the strong interfacial bond low-carbon refractory material: The raw materials are 40-55 wt% fused white corundum particles, 25-50 wt% fused white corundum fine powder, 2-4 wt% flake graphite, 4-6 wt% phenolic resin, 3-5 wt% aluminum powder and 1-5 wt% magnesium silicon nitride powder, and 3-6 wt% polyvinyl butyral is added as a coating agent. The raw materials and the coating agent are weighed and mixed according to their mass fractions. Step 2: The preparation method of the strong interfacial bond low-carbon refractory material is carried out according to the mass fraction mentioned in Step 1, following these steps: Step 2.1: First, mix the aluminum powder, the silicon nitride magnesium powder and the fused white corundum fine powder, stir for 1-4 hours, then add the polyvinyl butyral and stir for 2-5 hours; then place it in a high-temperature tube furnace and keep it at 600-700℃ for 2-5 hours under a nitrogen atmosphere to obtain the composite powder. Step 2.2: Add the phenolic resin to alcohol, stir and dilute to obtain mixture I; then add the composite powder to mixture I in 1 to 4 portions, and disperse by ultrasonication to obtain mixture II; Step 2.3: Stir the fused white corundum particles in a mixer for 20-30 minutes, then add the mixture II to the mixer and stir for 1-4 hours. Then add the flake graphite and the aluminum powder and stir for 3-6 hours to obtain mixture III. Step 2.4: The mixture III is pressed into shape under 170~200MPa and cured at 200~220℃ for 24~48h. Then it is placed in a high-temperature tube furnace and heated to 1200~1500℃ under nitrogen atmosphere, held for 2~5h, then cooled to 800~1100℃ and held for 1~4h. The furnace is then cooled to obtain a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride.

2. The preparation method of the low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride according to claim 1, characterized in that... The fused white fused alumina particles have an Al2O3 content ≥ 98wt% and a particle size of 1~3mm.

3. The preparation method of the low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride according to claim 1, characterized in that... The Al2O3 content of the fused white corundum fine powder is ≥98wt%; the particle size of the fused white corundum fine powder is ≥0.045mm.

4. The method for preparing a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride according to claim 1, characterized in that... The carbon content of the flake graphite is ≥98wt%; the particle size of the flake graphite is ≥0.045mm.

5. The method for preparing a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride according to claim 1, characterized in that... The MgSiN2 content of the silicon magnesium nitride powder is ≥98wt%; the particle size of the silicon magnesium nitride powder is ≥100nm.

6. The method for preparing a low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride according to claim 1, characterized in that... The aluminum powder has an Al content ≥ 98 wt% and a particle size ≥ 0.045 mm.

7. The preparation method of the low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride according to claim 1, characterized in that... The resin is a thermosetting phenolic resin or a thermoplastic phenolic resin.

8. A low-carbon refractory material with strong interfacial bonding based on magnesium silicon nitride, characterized in that... The strongly interfacially bonded low-carbon refractory material containing silicon-magnesium nitride is a strongly interfacially bonded low-carbon refractory material prepared by the preparation method of the strongly interfacially bonded low-carbon refractory material containing silicon-magnesium nitride according to any one of claims 1 to 7.

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