Casting alpha-beta corundum brick and preparation method thereof
The fused cast α-β corundum bricks prepared using specific raw materials and processes solve the structural porosity problem caused by the β phase transformation, achieving high density and high temperature stability, and improving corrosion resistance. They are suitable for float glass and photovoltaic glass furnaces.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHENGZHOU SUNRISE ADVANCED MATERIALS CO LTD
- Filing Date
- 2026-01-30
- Publication Date
- 2026-04-28
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of refractory material production technology, specifically relating to a cast α-β corundum brick and its preparation method. Background Technology
[0002] Melting and casting α β-corundum bricks are mainly composed of α-corundum. Al2O3 and β Al2O3 (generally Na2O·xAl2O3, where x is usually 5-11) is composed of two phases with a glass phase content of less than 1%. It has the advantages of not contaminating the glass melt and resisting alkaline vapor erosion. It is widely used in the refining section and upper structure of float glass and photovoltaic glass furnaces.
[0003] With the development of the glass industry, the daily melting capacity of furnaces is constantly increasing, and the melting temperature is also rising accordingly. This leads to a greater degree of erosion of the molten glass on the cast bricks, thus placing higher demands on the erosion resistance, high-temperature structural stability, and service life of refractory materials. The static resistance rate to molten glass erosion needs to be further reduced to meet the requirements of higher daily melting capacities and melting temperatures; at high temperatures, β... Corundum exchange towards α The corundum phase transformation, accompanied by volume changes, may lead to a loose brick structure and the formation of microcracks, which in turn accelerates erosion and spalling. There is still room for improvement in the density and mechanical strength of the products to resist stronger mechanical erosion and thermal stress.
[0004] Therefore, it is necessary to develop a melt-cast α-type polymer with higher erosion resistance, high-temperature phase stability, and high density. β-corundum bricks and their preparation process have significant industrial application value. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fused casting α with excellent erosion resistance, high-temperature phase stability and high density. β-corundum bricks and their preparation methods.
[0006] This invention is achieved through the following technical solution:
[0007] A cast α-β corundum brick comprises the following raw materials in parts by weight: 94-97 parts alumina, 0.3-1.2 parts spinel powder, 4-6 parts alkali powder, and 0.2-0.8 parts ytterbium oxide; wherein, The alumina raw material contains Al2O3 ≥ 99.5 wt%, Na2O < 0.35 wt%, SiO2 ≤ 0.15 wt%, Fe2O3 ≤ 0.05 wt%, and loss on ignition < 1.05 wt%. The alkali powder raw material contains Na2CO3 ≥ 99.5 wt% and Fe2O3 ≤ 0.05 wt%. The spinel micro powder raw material contains MgAl2O4 ≥ 99 wt%; The ytterbium oxide raw material contains Yb2O3 ≥ 98.5 wt%.
[0008] Furthermore, the cast α-β corundum brick is composed of the following chemical components: Na2O 2.5-3.5%, Yb2O3 0.2-0.8%, MgO 0.1-0.3%, SiO2+Fe2O3+TiO2+CaO≤0.3%, and Al2O3 balance, with the sum of each chemical component being 100%.
[0009] Furthermore, the D50 of the alumina raw material is 40-70 μm.
[0010] Furthermore, the particle size of the alkali powder raw material is ≤180um.
[0011] In this invention, the alkali powder provides Na2O as a crystal form regulator to stabilize β. The formation of the corundum phase regulates the α / β phase ratio; ytterbium oxide segregates at grain boundaries, inhibiting the transformation of the β phase to the α phase; spinel powder and ytterbium oxide act as heterogeneous nucleation cores, refining the grains of α and β corundum and achieving fine-grain strengthening. The particle size of the raw materials ensures the uniformity of mixing and reaction, reducing component segregation. SiO2, Fe2O3, TiO2, and CaO are impurities; high-purity raw materials can reduce the formation of the glassy phase.
[0012] The present invention also provides a method for preparing the above-mentioned cast α-β corundum brick, comprising the following steps: S1. Mix alumina and alkali powder raw materials, put them into a three-phase electric arc furnace for melting, melt at high temperature for 120 minutes, then add spinel powder and ytterbium oxide raw materials, adjust the electrodes to be close to the liquid surface and melt for 10-20 minutes, and then clarify. S2. Place the brick mold into the insulation box, fill the insulation box with insulation medium, then gently tap it to compact it, and finally set a casting riser on the top of the brick mold; S3. Pour the clarified molten liquid from step S1 into a brick mold and cover it with a thermal insulation medium at least 250mm thick. S4. Allow the brick to cool naturally until the temperature drops to 60°C. Demold and clean the sand. After grinding and cutting, the fused cast α-β corundum brick is obtained.
[0013] Furthermore, the heat-insulating medium is calcined alumina, and the calcined alumina contains Al2O3 ≥ 99wt%.
[0014] Furthermore, the brick casting mold is a sand mold made of graphite plate; the graphite plate has a bulk density of 1.63 g / cm³, a thermal conductivity of 120 W / m·K, and a coefficient of thermal expansion of 4 × 10⁻⁶. -6 / k.
[0015] Further, in step S1, the melting process includes first performing open arc melting at a current of 4000-5000A for 45-60 minutes, and then performing submerged arc melting at a current of 3800-4500A.
[0016] Furthermore, in step S3, the casting temperature is 1920-2060℃, and the casting speed is 50kg / s.
[0017] Furthermore, the α-phase conversion rate of the alumina raw material is ≥92%.
[0018] This invention uses calcined alumina as the insulation medium, which is the same as the main component of the brick blank. This prevents the surface of the brick blank from being contaminated or undergoing compositional changes, ensuring product purity and performance. It also provides uniform mechanical support, reducing cracking and deformation of the brick blank during the high-temperature softening stage. The graphite casting material has a low coefficient of thermal expansion, reducing the risk of cracking in the casting, and rapid cooling helps to form a fine α / β two-phase eutectic structure.
[0019] The beneficial effects of this invention are: The fused cast α-β corundum bricks prepared by this invention have a bulk density of up to 3.58 g / cm³, an apparent porosity of less than 3.1%, a room temperature compressive strength of up to 288 MPa, and excellent erosion resistance and high temperature phase stability.
[0020] In this invention, alkali powder stabilizes β The formation of the corundum phase and the segregation of ytterbium oxide at the grain boundaries inhibit the transformation from the β phase to the α phase; spinel powder and ytterbium oxide refine the grains of α and β corundum; under the combined action of the raw materials, the density of the product is improved, thereby improving its corrosion resistance.
[0021] This invention, by selecting raw materials with specific specifications and combining them with a special casting process, produces cast α-polymer with excellent corrosion resistance, high-temperature phase stability, and high density. β-corundum bricks ensure stability in the production process and product performance, resulting in a high pass rate. Detailed Implementation
[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0023] In the following embodiments, Alumina: purity 99.8wt%, SiO2 0.08wt%, Fe2O3 0.03wt%, Na2O 0.25wt%, loss on ignition 0.8wt%, D50 55μm, α The phase conversion rate was 95%; Alkali powder: purity 99.7wt%, Fe2O3 0.03wt%, particle size ≤150μm; Spinel micro powder: purity 99.3 wt%; Ytterbium oxide: purity 99.0 wt%.
[0024] Example 1 A cast α-β corundum brick comprises the following raw materials in parts by weight: 95.5 parts alumina, 0.7 parts spinel powder, 5.0 parts alkali powder, and 0.5 parts ytterbium oxide.
[0025] The method for preparing the cast α-β corundum brick includes the following steps: Alumina and alkali powder were mixed evenly and put into a three-phase electric arc furnace. First, open arc melting was carried out at a current of 4500A for 50 minutes, and then the current was switched to 4000A for submerged arc melting. 85 minutes after the start of submerged arc melting, spinel powder and ytterbium oxide were added, and the electrodes were adjusted to be close to the liquid surface. Melting was carried out at a current of 3800A for 15 minutes. Then, clarification was carried out at a current of 3200A for 10 minutes.
[0026] The brick casting mold is a sand mold made of graphite plate, which is placed in an insulated box beforehand, surrounded by calcined alumina, compacted, and equipped with risers. The clarified molten metal at 2000℃ is poured into the mold at a casting speed of 50 kg / s, and the risers are covered with a layer of calcined alumina approximately 300 mm thick. When the core temperature of the brick drops to approximately 60℃, it is demolded, the sand is removed, and after grinding and cutting, the fused cast α-β corundum brick is obtained.
[0027] Example 2 A cast α-β corundum brick comprises the following raw materials in parts by weight: 96 parts alumina, 0.4 parts spinel powder, 4.5 parts alkali powder, and 0.3 parts ytterbium oxide.
[0028] The method for preparing the cast α-β corundum brick includes the following steps: Alumina and alkali powder were mixed evenly and put into a three-phase electric arc furnace. First, open arc melting was carried out at a current of 4800A for 55 minutes, and then the current was switched to 4200A for submerged arc melting. 80 minutes after the start of submerged arc melting, spinel powder and ytterbium oxide were added, and the electrodes were adjusted to be close to the liquid surface. Melting was carried out at a current of 3700A for 12 minutes. Clarification was then carried out at a current of 3200A for 10 minutes.
[0029] The brick casting mold is a sand mold made of graphite plate, which is placed in an insulated box beforehand, surrounded by calcined alumina, compacted, and equipped with risers. The clarified molten metal at 2050℃ is poured into the mold at a casting speed of 50 kg / s, and the top of the riser is covered with a layer of calcined alumina approximately 300 mm thick. When the center temperature of the brick drops to approximately 60℃, it is demolded, the sand is removed, and after grinding and cutting, the fused cast α-β corundum brick is obtained.
[0030] Example 3 A cast α-β corundum brick comprises the following raw materials in parts by weight: 94.5 parts alumina, 0.4 parts spinel powder, 4.5 parts alkali powder, and 0.3 parts ytterbium oxide.
[0031] The method for preparing the cast α-β corundum brick includes the following steps: Alumina and alkali powder were mixed evenly and put into a three-phase electric arc furnace. First, open arc melting was carried out at a current of 4200A for 50 minutes, and then the current was switched to 3850A for submerged arc melting. 90 minutes after the start of submerged arc melting, spinel powder and ytterbium oxide were added, and the electrodes were adjusted to be close to the liquid surface. Melting was carried out at a current of 3800A for 15 minutes. Clarification was then carried out at a current of 3200A for 10 minutes.
[0032] The brick casting mold is a sand mold made of graphite plate, which is placed in an insulated box beforehand, surrounded by calcined alumina, compacted, and equipped with risers. The clarified molten metal at 1980℃ is poured into the mold at a casting speed of 50 kg / s, and the risers are covered with a layer of calcined alumina approximately 300 mm thick. When the core temperature of the brick drops to approximately 60℃, it is demolded, the sand is removed, and after grinding and cutting, the fused cast α-β corundum brick is obtained.
[0033] Comparative Example 1 A cast α-β corundum brick comprises the following raw materials in parts by weight: 96 parts alumina, 0.7 parts spinel powder, and 5.0 parts alkali powder.
[0034] The method for preparing the cast α-β corundum brick includes the following steps: Alumina and alkali powder were mixed evenly and put into a three-phase electric arc furnace. First, open arc melting was carried out at a current of 4500A for 50 minutes, and then the current was switched to 4000A for submerged arc melting. 85 minutes after the start of submerged arc melting, spinel powder was added, the electrode was adjusted to be close to the liquid surface, and melting was carried out at a current of 3800A for 15 minutes. Then, clarification was carried out at a current of 3200A for 10 minutes.
[0035] The brick casting mold is a sand mold made of graphite plate, which is placed in an insulated box beforehand, surrounded by calcined alumina, compacted, and equipped with risers. The clarified molten metal at 2000℃ is poured into the mold at a casting speed of 50 kg / s, and the risers are covered with a layer of calcined alumina approximately 300 mm thick. When the core temperature of the brick drops to approximately 60℃, it is demolded, the sand is removed, and after grinding and cutting, the fused cast α-β corundum brick is obtained.
[0036] Comparative Example 2 A cast α-β corundum brick comprises the following raw materials in parts by weight: 96.2 parts alumina, 5.0 parts alkali powder, and 0.5 parts ytterbium oxide.
[0037] The method for preparing the cast α-β corundum brick includes the following steps: Alumina and alkali powder were mixed evenly and put into a three-phase electric arc furnace. First, open arc melting was carried out at a current of 4500A for 50 minutes, and then the current was switched to 4000A for submerged arc melting. 85 minutes after the start of submerged arc melting, ytterbium oxide was added, the electrodes were adjusted to be close to the liquid surface, and melting was carried out at a current of 3800A for 15 minutes. Then, clarification was carried out at a current of 3200A for 10 minutes.
[0038] The brick casting mold is a sand mold made of graphite plate, which is placed in an insulated box beforehand, surrounded by calcined alumina, compacted, and equipped with risers. The clarified molten metal at 2000℃ is poured into the mold at a casting speed of 50 kg / s, and the risers are covered with a layer of calcined alumina approximately 300 mm thick. When the core temperature of the brick drops to approximately 60℃, it is demolded, the sand is removed, and after grinding and cutting, the fused cast α-β corundum brick is obtained.
[0039] Comparative Example 3 The traditional formula for α-β corundum bricks is as follows: 96.5 parts alumina, 4.8 parts soda ash, 0.5 parts silica sand, and 0.2 parts limestone.
[0040] The method for preparing the cast α-β corundum brick includes the following steps: Alumina, soda ash, silica sand, and limestone are mixed evenly and then put into a three-phase electric arc furnace. The mixture is melted in an open arc at a constant current for 135 minutes. Clarification is then carried out at a current of 3200A for 10 minutes.
[0041] Ordinary silica sand molds are placed in an insulated box beforehand, surrounded by calcined alumina, compacted, and equipped with risers. The clarified molten metal at 2000℃ is poured into the mold at a casting speed of 50 kg / s, and a layer of calcined alumina approximately 300 mm thick is placed on top of the risers. The bricks are demolded when the center temperature drops to approximately 60℃, the sand is removed, and the bricks are ground, cut, and processed to obtain cast α-β corundum bricks.
[0042] Comparative Example 4 The raw materials are the same as in Example 1; The method for preparing the cast α-β corundum brick includes the following steps: Alumina and alkali powder were mixed evenly and put into a three-phase electric arc furnace. A constant current open arc melting was used. After melting at high temperature for 135 minutes, spinel powder and ytterbium oxide were added, and open arc melting was continued for 15 minutes. Then, clarification was carried out with a clarification current of 3200A for 10 minutes.
[0043] The brick casting mold is a sand mold made of graphite plate, which is placed in an insulated box beforehand, surrounded by calcined alumina, compacted, and equipped with risers. The clarified molten metal at 2000℃ is poured into the mold at a casting speed of 50 kg / s, and the risers are covered with a layer of calcined alumina approximately 300 mm thick. When the core temperature of the brick drops to approximately 60℃, it is demolded, the sand is removed, and after grinding and cutting, the fused cast α-β corundum brick is obtained.
[0044] Effect Example Example 1 above 3 and Comparative Example 1 The physical properties of the prepared fused cast α-β corundum bricks were tested, and the test results are shown in Table 1.
[0045] Testing standards: Bulk density and apparent porosity are tested according to GB / T 2997 standard; The compressive strength test was conducted according to GB / T 5072 standard.
[0046] Table 1 Physical test results of cast α-β corundum bricks
[0047] Example 1 above 3 and Comparative Example 1 The prepared fused cast α-β corundum bricks were subjected to static resistance to glass melt erosion tests according to JC / T 806 standard, and the β-corundum phase change was tested after 1700℃×72h. The results are shown in Table 2.
[0048] Table 2. Erosion resistance and high-temperature phase stability of cast α-β corundum bricks
[0049] As shown in Tables 1 and 2, the cast α-β corundum bricks prepared in Examples 1-3 have high bulk density (greater than 3.58 g / cm³), low apparent porosity (less than 3.1%), and compressive strength (greater than 288 MPa), exhibiting high density. Their static resistance to molten glass erosion is ≤0.22 mm / 24h, indicating good resistance to molten glass erosion. Furthermore, the β-corundum phase remains stable at high temperatures without phase transformation. In Comparative Example 1, the β-corundum phase decreased by 8%, and the static resistance to molten glass erosion was 0.25 mm / 24h, indicating decreased high-temperature phase stability and erosion resistance. In Comparative Example 2, the apparent porosity increased to 3.8%, and the compressive strength decreased to 260 MPa, resulting in reduced density and decreased erosion resistance. Comparative Example 3 exhibited high porosity, poor erosion resistance, and unstable high-temperature phase. Therefore, the raw materials of this invention, through their combined action, improve the density of the product, thereby enhancing its erosion resistance.
[0050] The fused cast α-β corundum bricks prepared by this invention have a bulk density of up to 3.58 g / cm³, an apparent porosity of less than 3.1%, a room temperature compressive strength of up to 288 MPa, and excellent erosion resistance and high temperature phase stability.
[0051] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A cast α-β corundum brick, characterized in that, It comprises the following raw materials in parts by weight: 94-97 parts alumina, 0.3-1.2 parts spinel powder, 4-6 parts alkali powder, and 0.2-0.8 parts ytterbium oxide; wherein, The alumina raw material contains Al2O3 ≥ 99.5 wt%, Na2O < 0.35 wt%, SiO2 ≤ 0.15 wt%, Fe2O3 ≤ 0.05 wt%, and loss on ignition < 1.05 wt%. The alkali powder raw material contains Na2CO3 ≥ 99.5 wt% and Fe2O3 ≤ 0.05 wt%. The spinel micro powder raw material contains MgAl2O4 ≥ 99 wt%; The ytterbium oxide raw material contains Yb2O3 ≥ 98.5 wt%.
2. The cast α-β corundum brick according to claim 1, characterized in that, The cast α-β corundum brick is composed of the following chemical components: Na2O 2.5-3.5%, Yb2O3 0.2-0.8%, MgO 0.1-0.3%, SiO2+Fe2O3+TiO2+CaO≤0.3%, and Al2O3 balance, with the sum of all chemical components being 100%.
3. The cast α-β corundum brick according to claim 1, characterized in that, The alumina raw material has a D50 of 40-70 μm.
4. The cast α-β corundum brick according to claim 1, characterized in that, The particle size of the alkali powder raw material is ≤180um.
5. A method for preparing a cast α-β corundum brick according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Mix alumina and alkali powder raw materials, put them into a three-phase electric arc furnace for melting, melt at high temperature for 120 minutes, then add spinel powder and ytterbium oxide raw materials, adjust the electrodes to be close to the liquid surface and melt for 10-20 minutes, and then clarify. S2. Place the brick mold into the insulation box, fill the insulation box with insulation medium, then gently tap it to compact it, and finally set a casting riser on the top of the brick mold; S3. Pour the clarified molten liquid from step S1 into a brick mold and cover it with a thermal insulation medium at least 250mm thick. S4. Allow the brick to cool naturally until the temperature drops to 60°C. Demold and clean the sand. After grinding and cutting, the fused cast α-β corundum brick is obtained.
6. The method for preparing fused cast α-β corundum bricks according to claim 5, characterized in that, The heat-insulating medium is calcined alumina, and the Al2O3 content in the calcined alumina is ≥99wt%.
7. The method for preparing fused cast α-β corundum bricks according to claim 5, characterized in that, The brick casting mold is a sand mold made of graphite plate; the graphite plate has a bulk density of 1.63 g / cm³, a thermal conductivity of 120 W / m·K, and a coefficient of thermal expansion of 4 × 10⁻⁶. -6 / k.
8. The method for preparing fused cast α-β corundum bricks according to claim 5, characterized in that, In step S1, the melting process includes first performing open arc melting at a current of 4000-5000A for 45-60 minutes, and then performing submerged arc melting at a current of 3800-4500A.
9. The method for preparing fused cast α-β corundum bricks according to claim 5, characterized in that, In step S3, the casting temperature is 1920-2060℃, and the casting speed is 50kg / s.
10. The method for preparing fused cast α-β corundum bricks according to claim 5, characterized in that, The α-phase conversion rate of the alumina raw material is ≥92%.