Preparation method of multi-ceramic combined light magnesium carbonaceous composite material

Abstract

The application belongs to the technical field of light weight refractory material, and discloses a preparation method of a multi-ceramic combined light weight magnesium-carbon composite material; a precursor solution is prepared by mixing aluminum powder and deionized water under microwave hydration conditions, then a composite binder is prepared by stirring phenolic resin, the precursor solution and a catalyst under water bath conditions; after processes such as batching, mixing, molding, drying and microwave nitrogenization sintering, the low-carbonized multi-ceramic combined light weight magnesium-carbon composite material is prepared; the application has less raw materials, simple process, low preparation cost, and the prepared light weight magnesium-carbon composite material has superior performance and realizes low carbonization and light weight in a true sense.

Description

Technical Field

[0001] This invention belongs to the field of lightweight composite materials technology, specifically relating to a method for preparing a multi-ceramic bonded lightweight magnesium-carbon composite material. Background Technology

[0002] Magnesia-carbon composites play a crucial role in the slag line section of steel ladles due to their excellent mechanical strength and chemical stability. However, the high carbon content of traditional magnesia-carbon refractories leads to increased energy consumption during the smelting process and causes uneven temperature distribution in the molten steel due to heat loss. With the increasing demand for clean steel and energy-saving, emission-reducing modern production, research on magnesia-carbon refractories is inevitably moving towards low-carbon and energy-saving directions, making lightweight magnesia-carbon refractories a necessary development trend.

[0003] Among them, the patent document "A Lightweight Periacriticite-Silicon Carbide-Carbon Refractory Material and Its Preparation Method" (CN112811928A) discloses a method using modified porous periclase ceramic particles I, II, and III as aggregates, and modified porous periclase ceramic fine powder, elemental silicon powder, ultrafine graphite powder, and silicon carbide fine powder as matrices. After adding a catalyst and phenolic resin, the mixture is stirred, machine-pressed, dried, and calcined in a carbon-buried atmosphere to obtain a lightweight periclase-silicon carbide-carbon refractory material. This method requires preparing porous magnesium oxide agglomerate fine powder and porous alumina agglomerate fine powder with different modifications using magnesite and aluminum hydroxide micropowder. These are then mixed together to prepare a mixture, which is then calcined at a high temperature above 1630℃ to obtain porous periclase ceramics. The obtained periclase ceramic fine powder was added to a modification solution and a catalyst, and then crushed to prepare modified porous periclase ceramic fine powder. The modified porous raw material obtained above, along with other raw materials, was then used to prepare a lightweight periclase-silicon carbide-carbon refractory material. The preparation process involves four calcinations and vacuum preparation of the modification solution, making it complex.

[0004] "The Influence of Hollow Aggregates on the Mechanical Properties of Lightweight MgO-MgAl2O4-C Refractory Materials" (Huang Ke, Yin Chaofan, Wang Li, et al., The Influence of Hollow Aggregates on the Mechanical Properties of Lightweight MgO-MgAl2O4-C Refractory Materials [J]. Refractory Materials, 2025, 59(1):38-44.) MgO-MgAl2O4-C refractory materials were prepared using high-purity fused magnesia, self-made magnesia-alumina spinel hollow aggregate, α-Al2O3 micro powder, magnesia-alumina spinel powder, Si powder, Al powder, and flake graphite as main raw materials, and thermosetting phenolic resin as a binder, after carbon embedding heat treatment at 1200℃ and 1400℃. This preparation method involves preparing hollow magnesia-alumina spinel spheres and introducing them into MgO-C refractory materials, which, under carbon embedding conditions, form SiC and AlN ceramic phases in situ, thus improving the mechanical properties of the material.

[0005] "The Influence of Lightweight Corundum Aggregate on the Erosion Mechanism of Aluminum Magnesium Carbon Refractory Materials Used in the Impact Zone of Ladle Bottom" (Gao Jie, Chen Qilong, Liu Cheng, et al. The Influence of Lightweight Corundum Aggregate on the Erosion Mechanism of Aluminum Magnesium Carbon Refractory Materials Used in the Impact Zone of Ladle Bottom [J]. Journal of the Chinese Ceramic Society, 2024, 43(11): 4224-4231.) Introducing lightweight corundum aggregate into aluminum magnesium carbon refractory materials, with its high surface roughness and abundant micron-sized pores, can not only strengthen the bonding interface of the aggregate matrix, but also absorb thermal stress through micropores, significantly improving the erosion resistance and thermal shock stability of aluminum magnesium carbon refractory materials; at the same time, it can promote the formation of a dense and thick calcium hexaaluminate-spinel composite isolation layer on the hot surface, hindering the erosion and penetration of slag, and effectively inhibiting the oxidation of internal carbon. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing a lightweight magnesium-carbon composite material with multiple ceramic bonds. A precursor solution is prepared by mixing aluminum powder and deionized water under microwave hydration conditions. Then, a composite binder is prepared by mixing phenolic resin, the precursor solution, and a catalyst under stirring conditions in a water bath. Finally, a low-carbon, lightweight magnesium-carbon refractory material with multiple ceramic bonds is prepared through processes such as batching, mixing, molding, drying, and microwave nitriding calcination. This invention uses fewer raw materials, has a simple process, low preparation cost, and produces a lightweight magnesium-carbon composite material with superior performance, truly achieving low carbonization and lightweighting.

[0007] The technical solution adopted in this invention is: a method for preparing a multi-ceramic bonded lightweight magnesium-carbon composite material is as follows:

[0008] Step 1: Preparation of the composite binder;

[0009] The components are in parts by weight: 10-22 parts of metallic aluminum powder and 44-80 parts of deionized water are mixed and treated under microwave hydration conditions at 80-100℃ for 10-30 minutes to obtain a precursor solution with a concentration of 0.1-0.5 g / ml. Under the action of a water bath at 80℃ and a magnetic stirrer, the precursor solution and phenolic resin are mixed at a mass ratio of 0.2-1:1. Then, 0.2-1% of catalyst is added and stirred for 20-60 minutes to obtain a composite binder.

[0010] Step 2: The premixed material is composed of the following components by weight: 2-6 parts flake graphite, 32-52 parts sintered magnesia fine powder, and 36-60 parts activated alumina micro powder. The above raw materials are mixed in a ball mill for 0.5-2.5 hours to obtain the premixed material.

[0011] Step 3: Drying, curing, and calcination treatment;

[0012] Add 60-72 parts of magnesium-carbon composite aggregate and 1-5 parts of magnesium-aluminum spinel hollow spheres to a mixer. Slowly add 2-6 parts of composite binder. After the aggregate is uniformly coated with composite binder, add 30-38 parts of premix to the mixer and continue mixing for 20-60 minutes. After mixing evenly, press, dry and cure to obtain magnesium-carbon composite green body. Under microwave nitriding conditions, heat treat at 800℃-1200℃ for 20-60 minutes to obtain multi-ceramic bonded lightweight magnesium-carbon composite material.

[0013] The aluminum powder has a purity > 99% and a particle size ≤ 0.044 mm.

[0014] The phenolic resin is a thermosetting phenolic resin with a solid content of 20-40%.

[0015] The catalyst is one or two of analytical grade CeO2, FeMo alloy and La2O3.

[0016] The sintered magnesia in the premix has a purity >97% and a particle size ≤0.044mm.

[0017] The purity of the activated alumina micro powder in the premix is ​​>99%, and the particle size is ≤0.044mm.

[0018] The purity of the magnesium aluminum spinel hollow spheres in the premix is ​​>99%, and the particle size is ≤1mm.

[0019] This invention is applied to lightweight design in the field of magnesium-carbon refractory materials.

[0020] The microwave hydration in step one can promote the hydration of aluminum powder. By controlling the hydration time, the degree to which aluminum powder and water form a boehmite solution can be precisely controlled, thereby controlling the particle size and activity of the final alumina crystals.

[0021] In step three, the aggregate surface is first uniformly coated with a composite binder, and a secondary carbon conversion reaction occurs under microwave nitriding conditions; it reacts with trace amounts of oxygen in the environment to form a partial pressure of CO; providing sufficient partial pressure of CO for the in-situ formation of various ceramics in the environment.

[0022] In step three, microwave nitriding ensures uniform heating of the product using microwaves. Simultaneously, the introduction of lightweight materials leads to the enrichment of the gas phase within the ceramic pores, thereby providing impetus for the rapid nucleation and development of the ceramic phase inside the material. This method avoids the energy waste and long production cycles associated with traditional carbon material heating methods. This invention employs microwave nitriding, which, to a certain extent, reduces the reaction potential energy and formation temperature of AlN, MgAl2O4, and MgAlON by controlling the partial pressure of nitrogen.

[0023] This invention innovatively uses a composite binder, which is a combination of inorganic and organic components. The inorganic component is boehmite solution, AlOOH. The addition of boehmite solution provides more active alumina to the system, and a catalyst is added during the mixing process. On the one hand, it acts as a catalyst, and on the other hand, it helps to form magnesium aluminum spinel under high temperature.

[0024] According to thermodynamic conditions, the formation of AlN requires partial pressures of CO and N2. AlOOH readily dehydrates under microwave nitriding conditions to form highly reactive alumina, which reacts with CO in the environment to form an AlO gas phase. This gas phase readily reacts with N2 to form the AlN ceramic phase. AlN is a columnar whisker-like crystal and belongs to the category of ceramic reinforcing phases.

[0025] This invention innovatively reduces the amount of graphite added to 2-6 parts. Usually, when the carbon content is less than 10 parts, the carbon cannot form a continuous phase, resulting in a significant decrease in the final product's resistance to peeling and corrosion. This invention, however, compensates for this technical defect by forming a multi-ceramic crystalline phase, thereby achieving true low-carbonization.

[0026] The multi-ceramic phases of this invention are AlN, MgAl2O4, and MgAlON. These ceramic phases exist in the matrix and particle pores. Within the material, these ceramic phases enhance the bonding force between particles through whisker bridging, pull-out, and pinning effects, effectively alleviating stress at crack tips. Simultaneously, based on the excellent chemical stability and mechanical strength of the ceramic phases themselves, this not only overcomes the technical shortcomings of low carbon content, such as significantly reduced resistance to spalling and erosion, but also effectively resolves the contradiction between lightweight porous materials and mechanical properties, improving the overall performance of the material.

[0027] The beneficial effects of this invention are as follows: This invention prepares a boehmite solution by controlling the hydration of metallic aluminum powder through microwave hydration; a composite binder is prepared by combining the prepared boehmite solution and phenolic resin solution in a certain proportion; this binder has the characteristics of both organic and inorganic binders, and during the high-temperature process, it promotes the secondary carbon conversion of phenolic resin and promotes the formation of AlN, MgAl2O4 and MgAlON together with the boehmite solution; this invention pre-mixes and ball-mills flake graphite, magnesia fine powder and activated alumina micro powder, reducing the particle size of each raw material, increasing the contact probability of magnesia fine powder and activated alumina micro powder, and lowering the nucleation temperature of MgAl2O4 and MgAlON; thus truly achieving low carbonization and lightweighting.

[0028] This invention uses inexpensive and readily available raw materials, and features low cost and simple preparation process. The prepared multi-ceramic bonded lightweight magnesium-carbon composite material has excellent high temperature resistance, anti-stripping properties, and anti-corrosion performance. Attached Figure Description

[0029] Figure 1 The image shows a micro-area SEM image of the lightweight magnesium-carbon composite material prepared in Example 1 after heat treatment. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments. The embodiments of the present invention provide a multi-ceramic bonded lightweight magnesium-carbon composite material and its preparation method, wherein the purity of the aluminum powder is >99% and the particle size is ≤0.044mm; the phenolic resin is a thermosetting phenolic resin with a solid content of 20-40%; the purity of the sintered magnesia in the premix is ​​>97% and the particle size is ≤0.044mm; the purity of the activated alumina micropowder in the premix is ​​>99% and the particle size is ≤0.044mm; and the purity of the magnesium-aluminum spinel hollow spheres in the premix is ​​>99% and the particle size is ≤1mm.

[0031] Example 1

[0032] Step 1: Preparation of the composite binder;

[0033] The components are in parts by weight: 10 parts of metallic aluminum powder and 80 parts of deionized water are mixed and treated under microwave hydration conditions at 80~100℃ for 10~30 min to obtain a precursor solution with a concentration of 0.1 g / ml. Under the action of a water bath at 80℃ and a magnetic stirrer, the precursor solution and phenolic resin are mixed at a mass ratio of 0.2:1. Then, 1% of catalyst is added and stirred for 20~60 min to obtain the composite binder.

[0034] Step 2: The premixed material is composed of the following components by weight: 2 parts flake graphite, 52 parts sintered magnesia fine powder, and 46 parts activated alumina micro powder. The above raw materials are mixed in a ball mill for 1 hour to obtain the premixed material.

[0035] Step 3: Drying, curing, and calcination treatment;

[0036] Sixty parts of magnesium-carbon composite aggregate and five parts of magnesium-aluminum spinel hollow spheres were mixed in a mixer. Six parts of composite binder were slowly added. After the aggregate was uniformly coated with composite binder, 30 parts of premix were added to the mixer and the mixture was stirred for another 20 minutes. After being mixed evenly, the mixture was pressed, dried and cured to obtain a magnesium-carbon composite green body. Under microwave nitriding conditions, the green body was heat-treated at 800℃~1200℃ for 40 minutes to obtain a multi-ceramic bonded lightweight magnesium-carbon composite material.

[0037] The catalyst described in this embodiment is analytical grade CeO2.

[0038] Example 2

[0039] Step 1: Preparation of the composite binder;

[0040] The components are in parts by weight: 13 parts of metallic aluminum powder and 75 parts of deionized water are mixed and treated under microwave hydration conditions at 80~100℃ for 10~30 min to obtain a precursor solution with a concentration of 0.2 g / ml. Under the action of a water bath at 80℃ and a magnetic stirrer, the precursor solution and phenolic resin are mixed at a mass ratio of 1:1. Then, 0.2% of catalyst is added and stirred for 20 min to obtain the composite binder.

[0041] Step 2: The premixed material is composed of the following components by weight: 4 parts flake graphite, 36 parts sintered magnesia fine powder, and 60 parts activated alumina micro powder. The above raw materials are mixed in a ball mill for 0.5 hours to obtain the premixed material.

[0042] Step 3: Drying, curing, and calcination treatment;

[0043] 72 parts of magnesium-carbon composite aggregate and 1 part of magnesium-aluminum spinel hollow spheres were mixed in a mixer, and 6 parts of composite binder were slowly added. After the aggregate surface was uniformly coated with composite binder, 38 parts of premix were added to the mixer and the mixture was stirred for 60 minutes. After being mixed evenly, the mixture was pressed, dried and cured to obtain a magnesium-carbon composite green body. Under microwave nitriding conditions, it was heat-treated at 800℃~1200℃ for 60 minutes to obtain a multi-ceramic bonded lightweight magnesium-carbon composite material.

[0044] The catalyst described in this embodiment is an FeMo alloy.

[0045] Example 3

[0046] Step 1: Preparation of the composite binder;

[0047] The components are in parts by weight: 20 parts of metallic aluminum powder and 75 parts of deionized water are mixed and treated under microwave hydration conditions at 80~100℃ for 30 min to obtain a precursor solution with a concentration of 0.3 g / ml. Under the action of a water bath at 80℃ and a magnetic stirrer, the precursor solution and phenolic resin are mixed at a mass ratio of 0.8:1. Then, 0.5% of catalyst is added and stirred for 20~60 min to obtain the composite binder.

[0048] Step 2: The premixed material is composed of the following components by weight: 6 parts flake graphite, 40 parts sintered magnesia fine powder, and 54 parts activated alumina micro powder. The above raw materials are mixed in a ball mill for 2 hours to obtain the premixed material.

[0049] Step 3: Drying, curing, and calcination treatment;

[0050] 70 parts of magnesium-carbon composite aggregate and 4 parts of magnesium-aluminum spinel hollow spheres were mixed in a mixer. 5 parts of composite binder were slowly added. After the aggregate surface was uniformly coated with the composite binder, 35 parts of premix were added to the mixer and the mixture was stirred for another 30 minutes. After uniform mixing, the mixture was pressed, dried, and cured to obtain a magnesium-carbon composite green body. Under microwave nitriding conditions, it was heat-treated at 800℃~1200℃ for 50 minutes to obtain a multi-ceramic bonded lightweight magnesium-carbon composite material.

[0051] The catalyst described in this embodiment is La2O3.

[0052] Example 4

[0053] Step 1: Preparation of the composite binder;

[0054] The components are in parts by weight: 22 parts of metallic aluminum powder and 44 parts of deionized water are mixed and treated under microwave hydration conditions at 80~100℃ for 10~30 min to obtain a precursor solution with a concentration of 0.5 g / ml. Under the action of a water bath at 80℃ and a magnetic stirrer, the precursor solution and phenolic resin are mixed at a mass ratio of 0.9:1. Then, 0.5% of catalyst is added and stirred for 20~60 min to obtain the composite binder.

[0055] Step 2: The premixed material is composed of the following components by weight: 5 parts flake graphite, 40 parts sintered magnesia fine powder, and 55 parts activated alumina micro powder. The above raw materials are mixed in a ball mill for 1.5 hours to obtain the premixed material.

[0056] Step 3: Drying, curing, and calcination treatment;

[0057] 68 parts of magnesium-carbon composite aggregate and 4 parts of magnesium-aluminum spinel hollow spheres were mixed in a mixer, and 5 parts of composite binder were slowly added. After the aggregate surface was uniformly coated with composite binder, 35 parts of premix were added to the mixer and the mixture was stirred for another 35 minutes. After being mixed evenly, the mixture was pressed, dried and cured to obtain a magnesium-carbon composite green body. Under microwave nitriding conditions, it was heat-treated at 800℃~1200℃ for 45 minutes to obtain a multi-ceramic bonded lightweight magnesium-carbon composite material.

[0058] The catalyst described in this embodiment is a La2O3 and FeMo alloy.

[0059] This preparation method has the following advantages: the raw materials are non-toxic, harmless, and readily available, thus requiring lower production costs; the preparation process only requires ball milling, stirring, molding, drying, and firing, so the process is simple.

[0060] The multi-ceramic bonded lightweight magnesium-carbon composite material prepared in Example 1 was analyzed by microstructure. Figure 1The image shows a SEM image of the multi-ceramic bonded lightweight magnesium-carbon composite material prepared in Example 1 after microstructural analysis.

Claims

1. A method for preparing a multi-ceramic bonded lightweight magnesium-carbon composite material, characterized in that: Step 1: Preparation of the composite binder; The components, by weight, are as follows: 10-22 parts of aluminum powder and 44-80 parts of deionized water are mixed and treated under microwave hydration conditions at 80-100℃ for 10-30 minutes to obtain a precursor solution with a concentration of 0.1-0.5 g / ml. Under the action of a water bath at 80℃ and a magnetic stirrer, the precursor solution and phenolic resin are mixed at a mass ratio of 0.2-1:

1. Then, 0.2-1% of catalyst is added and stirred for 20-60 minutes. The composite binder is then prepared. The composite binder in step one is a combination of inorganic and organic components. The inorganic component is boehmite solution. The addition of boehmite solution provides more active alumina to the system, which forms magnesium aluminate spinel under subsequent high temperature. Step two: The premix composition by weight is: 2-6 parts flake graphite, 32-52 parts sintered magnesia fine powder, and 36-60 parts active alumina micro powder. The above raw materials are mixed in a ball mill for 0.5-2.5 hours to obtain the premix. Step three: Drying, curing, and calcination treatment. 60-72 parts of magnesium carbon composite aggregate and 1-5 parts of magnesium aluminate spinel hollow spheres are slowly added to the composite binder under the action of a mixer. After the composite binder is evenly coated on the surface of the aggregate, 30-38 parts of the premix are added to the mixer and stirred for 20-60 minutes. After being mixed evenly, it is pressed into shape, dried, and cured to obtain the magnesium carbon composite green body. Under microwave nitriding conditions, a lightweight magnesium-carbon composite material with multiple ceramic bonds can be obtained by heat treatment at 800℃~1200℃ for 20~60min; the multi-ceramic crystalline phases formed are AlN, MgAl2O4 and MgAlON coexisting.

2. The method for preparing the multi-ceramic bonded lightweight magnesium-carbon composite material according to claim 1, characterized in that: Phenolic resin is a thermosetting phenolic resin with a solid content of 20-40%.

3. The method for preparing the multi-ceramic bonded lightweight magnesium-carbon composite material according to claim 1, characterized in that: The purity of the magnesium aluminum spinel hollow spheres is >99%, and the particle size is ≤1mm.

4. The method for preparing the multi-ceramic bonded lightweight magnesium-carbon composite material according to claim 1, characterized in that: The catalyst is one or two of CeO2, FeMo alloy and La2O3.

5. The method for preparing the multi-ceramic bonded lightweight magnesium-carbon composite material according to claim 1, characterized in that: The purity of sintered magnesia in the premix is ​​>97%, and the particle size is ≤0.044mm.

6. The method for preparing the multi-ceramic bonded lightweight magnesium-carbon composite material according to claim 1, characterized in that: The purity of the activated alumina micro powder in the premix is ​​>99%, and the particle size is ≤0.044mm.

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