Low-thermal-conductivity multilayer composite magnesium-iron-aluminum spinel brick and preparation method thereof

Abstract

The application relates to the technical field of spinel brick preparation, and discloses a low-thermal-conductivity multilayer composite magnesium-iron-aluminum spinel brick, which comprises multiple layers of materials, each layer is composed of a layer of low-thermal-conductivity magnesium-iron-aluminum spinel material and a protective layer attached to the magnesium-iron-aluminum spinel material, the protective layer is made of ceramic material, the low-thermal-conductivity magnesium-iron-aluminum spinel material is composed of magnesium-iron-aluminum oxides, the thermal conductivity coefficient of the low-thermal-conductivity magnesium-iron-aluminum spinel material is less than 0.5 W / mK, and the magnesium-iron-aluminum oxides have the following chemical composition: MgO:Fe2O3:Al2O3. By using the low-thermal-conductivity magnesium-iron-aluminum spinel material and the attached protective layer, the composite material has a low thermal conductivity coefficient, so that the material has a wide application potential in the fields of heat insulation and energy saving, can effectively reduce heat conduction and energy loss, and solves the problem that harmful substances in raw materials can cause environmental pollution after use, protects the environment and reduces the environmental pollution.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of spinel brick preparation, in particular to a low-thermal-conductivity multi-layer composite magnesium-iron-aluminum spinel brick and a preparation method thereof. BACKGROUND

[0002] The refractory material for the high-temperature zone of a cement kiln has developed from the earliest clay brick and magnesia-chrome brick to the current magnesium-aluminum spinel brick, magnesium-zirconia brick and magnesium-dolomite brick. The magnesia-chrome brick has good load softening temperature, high-temperature strength, corrosion resistance and thermal shock stability, but it leaves Cr6+ after use, which pollutes the environment. The magnesium-aluminum spinel brick has good corrosion resistance, but it has poor kiln skin hanging performance. The magnesium-zirconia brick has good thermal shock stability and good alkali corrosion resistance, but it has high cost and complex process. The magnesium-calcium dolomite brick has good kiln skin hanging performance and high-temperature performance, but it is easy to hydrate and is inconvenient to store and transport. Although the magnesia-chrome refractory material pollutes the environment, it is still widely used in the cement kiln due to its excellent performance.

[0003] The patent No. CN200710189925.5 discloses a magnesium-aluminum-chromium composite spinel brick, which is made of synthetic magnesium-aluminum-chromium spinel, synthetic magnesium-aluminum spinel, magnesia, chromium concentrate and chromium oxide, and is formed by pressing, dried and then fired at high temperature. The invention uses the magnesium-aluminum-chromium composite spinel raw material to solve the problem of the lack of chromium resources in China and reduce the production cost. However, the product contains chromium, which pollutes the environment after use, and the performance of the product cannot meet the requirements of the high-temperature zone refractory brick of the existing cement kiln. SUMMARY

[0004] In view of the defects of the prior art, the present application provides a low-thermal-conductivity multi-layer composite magnesium-iron-aluminum spinel brick and a preparation method thereof, which solves the problem that the harmful substances in the raw material pollute the environment after use.

[0005] To achieve the above object, the present application is implemented by the following technical scheme: a low-thermal-conductivity multi-layer composite magnesium-iron-aluminum spinel brick, which comprises multiple layers of materials, each layer being composed of a layer of magnesium-iron-aluminum spinel material with low thermal conductivity and a layer of protective layer attached thereto, and the protective layer being composed of ceramic material.

[0006] Preferably, the magnesium-iron-aluminum spinel material with low thermal conductivity is composed of magnesium-iron-aluminum oxide, and the thermal conductivity coefficient is less than 0.5 W / mK.

[0007] Preferably, the magnesium-iron-aluminum oxide has the following chemical composition: MgO: Fe2O3: Al2O3, wherein the molar ratio of MgO is 0.4-0.6, the molar ratio of Fe2O3 is 0.2-0.4, and the molar ratio of Al2O3 is 0.1-0.3.

[0008] Preferably, the ceramic material is selected from silicon nitride, aluminum nitride or aluminum oxide.

[0009] Preferably, the thickness of the ceramic material is 5-50 microns.

[0010] Preferably, the number of layers of the multiple layers of material is 2-10 layers.

[0011] A low-thermal-conductivity multilayer composite magnesioferrit-spinel brick preparation method, comprising the following steps:

[0012] Step one, preparing magnesioferrit oxide, ceramic material and binder;

[0013] Step two, mixing magnesioferrit oxide, ceramic material and binder in a certain proportion;

[0014] Step three, ball milling to refine the raw material particles;

[0015] Step four, forming the refined raw material;

[0016] Step five, sintering to form a firm bond between the layers

[0017] Preferably, in step one, the binder is selected from organic or inorganic adhesives.

[0018] Preferably, in step three, the ball milling step is 1-10 hours.

[0019] Preferably, in step five, the sintering step is at a temperature of 1200-1600°C and is carried out under inert gas.

[0020] The present application provides a low-thermal-conductivity multilayer composite magnesioferrit-spinel brick and its preparation method. It has the following beneficial effects:

[0021] 1. The present application uses low-thermal-conductivity magnesioferrit-spinel material and attached protective layer, and the composite material achieves a low thermal conductivity, which makes the material have a wide application potential in the field of thermal insulation and energy saving, effectively reduces heat conduction and energy loss, and solves the problem of environmental pollution caused by harmful substances in raw materials after use, protects the environment and reduces environmental pollution.

[0022] 2. The present application controls the chemical composition ratio of magnesioferrit oxide to ensure the optimization of the structure and performance of the composite material. This composition selection makes the material have high stability, strength and durability, and improves the reliability of the material in various application environments.

[0023] 3、The ceramic protective layer attached to the magnesium-iron-aluminum spinel material not only provides additional thermal insulation function, but also protects the material from external environmental erosion and damage, the presence of the protective layer effectively prolongs the service life of the composite material, reduces the maintenance and replacement cost.

[0024] 4、The preparation method combines the steps of raw material preparation, ball milling, molding and sintering, etc., to ensure the formation of the hierarchical structure of the composite material and the firmness of the interlayer combination, at the same time, the sintering process under inert gas can improve the purity and stability of the material, and ensure the consistency and reliability of the material. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] Embodiment one:

[0027] The embodiment of the present application provides a low-thermal-conductivity multi-layer composite magnesium-iron-aluminum spinel brick, which comprises a plurality of layers of materials, the number of layers formed by the plurality of layers of materials is 4, each layer is composed of a layer of low-thermal-conductivity magnesium-iron-aluminum spinel material and a protective layer attached thereto, the protective layer provides additional protection and thermal insulation function, and the protective layer is composed of ceramic material, which can prevent external environment from eroding and damaging the magnesium-iron-aluminum spinel material and provide additional thermal insulation effect, the ceramic material is selected from silicon nitride, the low-thermal-conductivity magnesium-iron-aluminum spinel material is composed of magnesium-iron-aluminum oxide, the magnesium-iron-aluminum oxide has a low thermal conductivity, which can effectively reduce heat conduction and improve thermal insulation performance, the thermal conductivity is less than 0.5 W / mK, the magnesium-iron-aluminum oxide has the following chemical composition: MgO: Fe2O3: Al2O3, wherein the molar ratio of MgO is 0.5, the molar ratio of Fe2O3 is 0.3, and the molar ratio of Al2O3 is 0.2, by controlling the chemical composition ratio, the structure and performance of the material can be optimized, which is more suitable for the preparation of low-thermal-conductivity composite material, and the thickness of the ceramic material is 20 μm, which ensures the effectiveness of the protective layer and does not increase the weight and complexity of the material.

[0028] A low-thermal-conductivity multi-layer composite magnesium-iron-aluminum spinel brick preparation method comprises the following steps:

[0029] Step one, prepare magnesium-iron-aluminum oxide, ceramic material and organic adhesive, the magnesium-iron-aluminum oxide is a compound composed of MgO, Fe2O3 and Al2O3;

[0030] Step two, mix magnesium iron aluminum oxide, ceramic material and binder in a certain proportion;

[0031] Step three, ball milling for 4h, the purpose of ball milling is to refine the particle size of the raw materials, increase their surface area, and facilitate subsequent molding and sintering processes;

[0032] Step four, the ball-milled raw materials are subjected to molding treatment, which can be done by pressing. During the molding process, proper pressure and temperature need to be maintained to ensure that the resulting bricks have good shape and density;

[0033] Step five, sintering at a temperature of 1350℃, during the sintering process, the materials in each layer will react with each other, forming a firm bond between the layers, and the process is carried out in an inert gas, which can prevent oxidation and contamination of the materials.

[0034] The finished product is prepared according to the above method and raw materials, and the thermal conductivity performance test and other performance tests are carried out, and the data are recorded in Table 1.

[0035] Example two:

[0036] The embodiment of the present application provides a low-thermal-conductivity multi-layer composite magnesioferrite-alumina spinel brick, which comprises a plurality of layers of materials, the number of layers formed by the plurality of layers of materials is 1, and the layer is composed of a layer of low-thermal-conductivity magnesioferrite-alumina spinel material. The low-thermal-conductivity magnesioferrite-alumina spinel material is composed of magnesium iron aluminum oxide, which has a low thermal conductivity and can effectively reduce heat conduction and improve heat insulation performance. The thermal conductivity is less than 0.5 W / mK. The magnesium iron aluminum oxide has the following chemical composition: MgO: Fe2O3: Al2O3, wherein the molar ratio of MgO is 0.5, the molar ratio of Fe2O3 is 0.3, and the molar ratio of Al2O3 is 0.2. By controlling the proportion of the chemical composition, the structure and performance of the material can be optimized, so that it is more suitable for the preparation of low-thermal-conductivity composite materials. This design not only ensures the effectiveness of the protective layer, but also does not increase the weight and complexity of the material.

[0037] A low-thermal-conductivity multi-layer composite magnesioferrite-alumina spinel brick preparation method, comprising the following steps:

[0038] Step one, prepare magnesium iron aluminum oxide and organic adhesive, the magnesium iron aluminum oxide is a compound composed of MgO, Fe2O3 and Al2O3;

[0039] Step two, mix magnesium iron aluminum oxide and binder in a certain proportion;

[0040] Step three, ball milling for 4h to refine the raw material particles, the purpose of ball milling is to refine the raw material particles and increase their surface area, which is beneficial to the subsequent molding and sintering process;

[0041] Step four, the ball-milled raw materials are subjected to molding treatment, which can be done by pressing. During the molding process, proper pressure and temperature need to be maintained to ensure that the resulting bricks have good shape and density;

[0042] Step five, sintering at a temperature of 1350℃, during the sintering process, the materials in each layer will react with each other, forming a firm bond between the layers, and the sintering is carried out in an inert gas, which can prevent the oxidation and contamination of the materials.

[0043] The difference between this embodiment and Example 1 is that it is a single-layer magnesioferrit-spinel brick, which has the same chemical composition as the magnesioferrit-spinel material in Example 1. The brick is subjected to the same ball milling, molding and sintering treatment, but does not have an additional protective layer. The finished product is made according to the above method and subjected to thermal conductivity testing and various performance tests, and the data is recorded in Table 1.

[0044] Example three:

[0045] The embodiment of the present application provides a low-thermal-conductivity multi-layer composite magnesioferrit-spinel brick, which comprises a plurality of layers of material, the number of layers of the plurality of layers of material is 10, each layer is composed of a layer of low-thermal-conductivity magnesioferrit-spinel material and a layer of protective layer attached thereto, the protective layer provides additional protection and thermal insulation function, and the protective layer is composed of ceramic material, which can prevent the erosion and damage of the external environment to the magnesioferrit-spinel material and provide additional thermal insulation effect, the ceramic material is selected from silicon nitride, the low-thermal-conductivity magnesioferrit-spinel material is composed of magnesioferrit-oxide, which has a low thermal conductivity, can effectively reduce heat conduction and improve thermal insulation performance, and has a thermal conductivity of less than 0.5 W / mK, the magnesioferrit-oxide has the following chemical composition: MgO: Fe2O3: Al2O3, wherein the molar ratio of MgO is 0.5, the molar ratio of Fe2O3 is 0.3, and the molar ratio of Al2O3 is 0.2, by controlling the chemical composition ratio, the structure and performance of the material can be optimized, which is more suitable for the preparation of low-thermal-conductivity composite material, and the thickness of the ceramic material is 20μm, which ensures the effectiveness of the protective layer and does not increase the weight and complexity of the material.

[0046] A method for preparing a low-thermal-conductivity multi-layer composite magnesioferrit-spinel brick, comprising the following steps:

[0047] Step one, prepare magnesium iron aluminum oxide, ceramic material and organic adhesive, magnesium iron aluminum oxide is a compound composed of MgO, Fe2O3 and Al2O3;

[0048] Step two, mix magnesium iron aluminum oxide, ceramic material and binder according to a certain proportion;

[0049] Step three, ball milling for 4h, so that the raw material particles are refined, the purpose of ball milling is to refine the raw material particles and increase their surface area, which is beneficial to the subsequent forming and sintering process;

[0050] Step four, the raw material after ball milling is subjected to forming treatment, which can be pressed. During the forming process, proper pressure and temperature need to be maintained to ensure that the obtained bricks have good shape and density;

[0051] Step five, sintering temperature is set at 1350℃, during the sintering process, the materials between the layers will react with each other, forming a firm bond between the layers, and it is carried out under inert gas, sintering under the protection of inert gas can avoid oxidation and pollution of the material.

[0052] This example is different from example one, it is a 10-layer structure of magnesium iron aluminum spinel brick, its chemical composition is the same as that of the magnesium iron aluminum spinel material in example one, the brick is subjected to the same ball milling, forming and sintering treatment, but the number of layers is more, according to the above method, the finished product is made, and the heat conductivity performance test and various performance tests are carried out, and the data are recorded in table one.

[0053]

[0054]

[0055] Table one

[0056] In summary, when the number of layers of the multi-layer magnesium iron aluminum spinel brick is four, whether it is the thermal conductivity, compressive strength, load softening temperature, thermal shock stability, etc. The comprehensive performance is excellent, and it shows that the design of multi-layer structure and ceramic protective layer effectively reduces the heat conduction, provides good heat insulation effect, and through the ball milling, forming and sintering steps, the density and bonding of the material can be ensured, so that a firm bond is formed between the layers.

[0057] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A low thermal conductivity multilayer composite magnesium-iron-aluminum spinel brick, comprising multiple layers of material, characterized in that, Each layer consists of a layer of low thermal conductivity magnesium-iron-aluminum spinel material and a protective layer attached thereto, wherein the protective layer is made of ceramic material. The low thermal conductivity magnesium-iron-aluminum spinel material is composed of magnesium-iron-aluminum oxide with a thermal conductivity of less than 0.5 W / mK. The magnesium-iron-aluminum oxide has the following chemical composition: MgO:Fe2O3:Al2O3, wherein the molar proportion of MgO is 0.4-0.6, the molar proportion of Fe2O3 is 0.2-0.4, and the molar proportion of Al2O3 is 0.1-0.

3. The ceramic material is selected from silicon nitride, aluminum nitride, or aluminum oxide. The material consists of 2-10 layers, and the thickness of the protective layer is 5-50 μm.

2. A method for preparing a low thermal conductivity multilayer composite magnesium-iron-aluminum spinel brick, as described in claim 1, characterized in that, Includes the following steps: Step 1: Prepare magnesium iron aluminum oxide, ceramic materials, and binders; Step 2: Mix magnesium iron aluminum oxide, ceramic materials and binder in a certain proportion; Step 3: Perform ball milling to refine the raw material particles; Step 4: Shape the refined raw materials; Step 5: Sintering is performed to form a strong bond between the layers.

3. The method for preparing a low thermal conductivity multilayer composite magnesium-iron-aluminum spinel brick according to claim 2, characterized in that, In step one, the adhesive is selected from organic adhesives or inorganic adhesives.

4. The method for preparing a low thermal conductivity multilayer composite magnesium-iron-aluminum spinel brick according to claim 2, characterized in that, In step three, the ball milling process takes 1 to 10 hours.

5. The method for preparing a low thermal conductivity multilayer composite magnesium-iron-aluminum spinel brick according to claim 2, characterized in that, In step five, the sintering temperature is 1200–1600°C, and the process is carried out under an inert gas atmosphere.

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