High-temperature anti-erosion cast high-zirconium brick and application thereof

Abstract

The invention relates to a high-temperature anti-erosion cast high-zirconium brick and application thereof, and belongs to the technical field of refractory materials. The high-zirconium brick is prepared from the following components in percentage by mass: 96.4 to 97.6 percent of ZrO2, 1.18 to 1.70 percent of SiO2, 0.15 to 0.80 percent of Al2O3, 0.04 to 0.08 percent of Na2O, 0.02 to 0.06 percent of K2O, 0.20 to 0.30 percent of La2O3, 0.20 to 0.30 percent of SnO2 and less than 0.10 percent of other impurities. The method is characterized in that La2Sn2O7 is adopted as a raw material, La2O2 generated through decomposition in the high-temperature casting process serves as a heterogeneous nucleation core refined grain structure, and the high-temperature strength and toughness are improved; meanwhile, SnO2 is decomposed in a reducing atmosphere to release oxygen, bubbles are promoted to merge and escape, the porosity is remarkably reduced, and the density is improved. The data of the embodiment shows that the volume density of the brick body reaches 5.59-5.68 g / cm < 3 >, the porosity is lower than 0.61%, the anti-erosion rate in 1500 DEG C molten glass is as low as 0.28-0.34 mm / 24 h, and the brick shows excellent anti-erosion performance and high-temperature stability and is suitable for severe industrial environments such as a glass kiln.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a high-temperature erosion-resistant cast high-zirconium brick and its application. Background Technology

[0002] Fused cast refractory materials, especially fused cast high zirconium bricks, are widely used in key parts of high-temperature industrial furnaces such as glass melting furnaces and metallurgical furnaces due to their dense crystal structure, high mechanical strength, and excellent erosion resistance. These parts include the pool walls, feeding ports, and flow channels of glass melting furnaces. Their performance directly determines the service life and production efficiency of the furnace.

[0003] The main component of cast high-zirconium bricks is zirconium oxide (ZrO2), typically exceeding 90%. However, pure zirconium oxide undergoes a crystal transformation between monoclinic (m), tetragonal (t), and cubic (c) phases during cooling. The tetragonal-to-monoclinic (t→m) transformation, occurring around 1000℃, is accompanied by approximately 3-5% volume expansion, leading to significant internal stress and cracking within the brick. To address this issue, existing technologies typically add appropriate stabilizers to ZrO2, such as calcium oxide (CaO), yttrium oxide (Y2O3), or magnesium oxide (MgO). These stabilizers form a stable cubic or metastable tetragonal phase at room temperature, thus preventing destructive phase transformations.

[0004] While the application of the aforementioned stabilizers has addressed the phase transformation cracking problem of zirconia to some extent, existing cast high-zirconia bricks still suffer from insufficient phase stability at long-term high temperatures and a bottleneck in erosion resistance caused by the grain boundary glass phase when facing increasingly demanding high-temperature conditions. Furthermore, in pursuit of high erosion resistance, it is generally desirable for the brick body to have the highest possible density and zirconia content, but this often leads to a decrease in material toughness and a deterioration in thermal shock resistance. How to maintain extremely high erosion resistance while also ensuring good thermal shock resistance remains a challenge in current technologies.

[0005] Therefore, there is an urgent need in this field to develop a new type of fused cast high zirconium brick that not only needs to have high strength at both room temperature and high temperature, but more importantly, it needs to have excellent long-term phase stability and strong resistance to erosion in harsh chemical environments, thereby significantly extending its service life in high-temperature industrial kilns. Summary of the Invention

[0006] In order to solve the technical problems existing in the background art, the present invention uses La2Sn2O7 to stabilize cast high zirconium bricks, which can significantly improve the erosion resistance of cast high zirconium bricks while taking into account a certain degree of thermal stability.

[0007] One object of the present invention is to provide a high-temperature erosion-resistant cast high-zirconium brick, characterized in that, by mass fraction, it comprises the following components: ZrO2: 96.4-97.6%, SiO2: 1.18-1.70%, Al2O3: 0.15-0.80%, Na2O: 0.04-0.08%, K2O: 0.02-0.06%, La2O3: 0.20-0.30%, SnO2: 0.20-0.30%, and other impurities less than 0.10%.

[0008] Furthermore, the specific contents of each component in the high-temperature erosion-resistant cast high-zirconium brick are as follows: 97.13% ZrO2, 1.60% SiO2, 0.60% Al2O3, 0.06% Na2O, 0.04% K2O, 0.25% La2O3, 0.25% SnO2, and the contents of other components are less than 0.10%.

[0009] Furthermore, the mass ratio of tin oxide to lanthanum oxide in the high-temperature corrosion-resistant cast high-zirconium brick is 1-1.1:1.

[0010] Another object of the present invention is to provide a method for preparing high-temperature erosion-resistant cast high-zirconium bricks, characterized by comprising the following steps: S1: Take the corresponding raw materials according to the above high zirconium brick ratio, the raw materials include desilication zircon, silica source, sodium oxide source and La2Sn2O7; S2: The uniformly mixed raw materials are melted in an electric arc furnace to form a molten liquid; S3: The molten liquid is poured into a mold and solidified, then heat-treated and annealed to obtain the high-zirconium brick.

[0011] Furthermore, in step S3, the casting temperature is ≥1950 degrees Celsius, and the casting rate is 10–50 kg / s.

[0012] Furthermore, the preparation method of La2Sn2O7 in S1 is as follows: a. Dissolve the lanthanum and tin precursors in deionized water in stoichiometric ratio; b. Add a complexing agent, heat and stir to form a uniform sol, and heat to 300 degrees Celsius to obtain the precursor powder; c. Calcine the precursor powder to obtain La2Sn2O7; Furthermore, in step a, the precursor of lanthanum is either lanthanum nitrate or lanthanum citrate, the precursor of tin is tin chloride, and the molar ratio of lanthanum to tin is 1:1.

[0013] Furthermore, the complexing agent in step b is citric acid, and the molar ratio of citric acid to metal ions is 1-2:1; Furthermore, the specific calcination conditions in step c are: calcination at 600-800 degrees Celsius for 2-4 hours.

[0014] Another objective of this invention is to provide the application of high-temperature erosion-resistant cast high-zirconium bricks in the field of glass furnaces. Beneficial effects

[0015] This invention utilizes La2Sn2O7 as one of the raw materials for cast high-zirconium bricks. At high temperatures, La2Sn2O7 decomposes to produce lanthanum oxide and tin oxide. The resulting lanthanum oxide acts as a heterogeneous nucleation core, inhibiting the growth of ZrO2 grains and forming a fine, uniform microstructure, thereby improving the material's fracture toughness and high-temperature strength. Furthermore, during the preparation of cast high-zirconium bricks, as the system temperature decreases, the viscosity of the casting liquid significantly increases, making it difficult to effectively remove gases formed during the smelting stage and those entrained during casting. The presence of these residual pores significantly reduces the material's density. In this invention, the tin oxide generated, under the condition that the casting liquid is in contact with the graphite mold, creates a reducing atmosphere, promoting the reduction reaction of tin oxide and releasing oxygen. The generated oxygen bubbles combine with surrounding small bubbles. According to the principle of bubble merging, small bubbles merge into larger bubbles. These larger bubbles, under buoyancy, more easily rise from the melt and escape, reducing the number of internal bubbles and thus significantly improving the density of the cast high-zirconium bricks and effectively enhancing their corrosion resistance. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] It should be noted that the preparation methods of the cast high-zirconium bricks in the following embodiments and comparative examples are as follows: According to the corresponding proportion of high zirconium bricks, desilicationized zircon, silica source, sodium oxide source and La2Sn2O7 are taken; heated and melted in an electric arc furnace to obtain molten liquid; the molten liquid is poured into a mold at a casting temperature ≥1950 degrees Celsius and a casting rate of 10-50 kg / s to solidify, held for annealing, and processed to obtain the high zirconium bricks.

[0018] The preparation method of La2Sn2O7 is as follows: Lanthanum nitrate La(NO3)3·6H2O and SnCl4·5H2O were dissolved in deionized water at a stoichiometric ratio of 1:1. Citric acid was added, with a molar ratio of citric acid to metal ions of 2:1. The mixture was heated and stirred to form a homogeneous sol. Heating continued to evaporate the water, and the viscosity of the solution gradually increased, eventually forming a transparent gel. The gel was transferred to a heating plate and heated to 300°C. The gel underwent self-propagating combustion, producing a large amount of gas and yielding a fluffy black precursor powder. The powder obtained from the combustion was calcined at 600°C–800°C for 2–4 hours to obtain well-crystallized La2Sn2O7 powder. Example

[0019] ZrO2: 97.60%; SiO2: 1.58%; Al2O3: 0.35%; Na2O: 0.04%; K2O: 0.02%; La2O3: 0.20%; SnO2: 0.20%; and the contents of other components are less than 0.10%.

[0020] In this embodiment, the raw materials for lanthanum oxide and tin oxide in the fused cast high-zirconium brick are La2Sn2O7, and the specific preparation method is as follows: Lanthanum nitrate La(NO3)3·6H2O and SnCl4·5H2O were dissolved in deionized water at a stoichiometric ratio of 1:1. Citric acid was added, with a molar ratio of citric acid to metal ions of 2:1. The mixture was heated and stirred to form a homogeneous sol. Heating continued to evaporate the water, and the solution viscosity gradually increased, eventually forming a transparent gel. The gel was transferred to a heating plate and heated to 300°C. The gel underwent self-propagating combustion, producing a large amount of gas and yielding a fluffy black precursor powder. The powder obtained from the combustion was calcined at 700°C for 3 hours to obtain well-crystallized La2Sn2O7 powder. Example

[0021] It contains 96.66% ZrO2, 1.70% SiO2, 0.80% Al2O3, 0.08% Na2O, 0.06% K2O, 0.30% La2O3, and 0.30% SnO2, with other components comprising less than 0.10%.

[0022] In this embodiment, the raw materials for lanthanum oxide and tin oxide in the fused cast high-zirconium brick are La2Sn2O7, and the specific preparation method is as follows: Lanthanum nitrate La(NO3)3·6H2O and SnCl4·5H2O were dissolved in deionized water at a stoichiometric ratio of 1:1. Citric acid was added, with a molar ratio of citric acid to metal ions of 2:1. The mixture was heated and stirred to form a homogeneous sol. Heating continued to evaporate the water, and the solution viscosity gradually increased, eventually forming a transparent gel. The gel was transferred to a heating plate and heated to 300°C. The gel underwent self-propagating combustion, producing a large amount of gas and yielding a fluffy black precursor powder. The powder obtained from the combustion was calcined at 700°C for 3 hours to obtain well-crystallized La2Sn2O7 powder. Example

[0023] It contains 97.13% ZrO2, 1.60% SiO2, 0.06% Al2O3, 0.06% Na2O, 0.04% K2O, 0.25% La2O3, and 0.25% SnO2, with other components comprising less than 0.10%.

[0024] In this embodiment, the raw materials for lanthanum oxide and tin oxide in the fused cast high-zirconium brick are La2Sn2O7, and the specific preparation method is as follows: Lanthanum nitrate La(NO3)3·6H2O and SnCl4·5H2O were dissolved in deionized water at a stoichiometric ratio of 1:1. Citric acid was added, with a molar ratio of citric acid to metal ions of 2:1. The mixture was heated and stirred to form a homogeneous sol. Heating continued to evaporate the water, and the solution viscosity gradually increased, eventually forming a transparent gel. The gel was transferred to a heating plate and heated to 300°C. The gel underwent self-propagating combustion, producing a large amount of gas and yielding a fluffy black precursor powder. The powder obtained from the combustion was calcined at 700°C for 3 hours to obtain well-crystallized La2Sn2O7 powder. Example

[0025] It contains 97.00% ZrO2, 1.65% SiO2, 0.70% Al2O3, 0.05% Na2O, 0.03% K2O, 0.28% La2O3, and 0.28% SnO2, with other components comprising less than 0.10%.

[0026] In this embodiment, the raw materials for lanthanum oxide and tin oxide in the fused cast high-zirconium brick are La2Sn2O7, and the specific preparation method is as follows: Lanthanum nitrate La(NO3)3·6H2O and SnCl4·5H2O were dissolved in deionized water at a stoichiometric ratio of 1:1. Citric acid was added, with a molar ratio of citric acid to metal ions of 2:1. The mixture was heated and stirred to form a homogeneous sol. Heating continued to evaporate the water, and the solution viscosity gradually increased, eventually forming a transparent gel. The gel was transferred to a heating plate and heated to 300°C. The gel underwent self-propagating combustion, producing a large amount of gas and yielding a fluffy black precursor powder. The powder obtained from the combustion was calcined at 700°C for 3 hours to obtain well-crystallized La2Sn2O7 powder.

[0027] Example <![CDATA[Apparent density (g / cm -3 ).]]> Porosity (%) Resistance to molten glass erosion rate (mm) Example 1 5.61 0.61 0.33 Example 2 5.59 0.59 0.32 Example 3 5.63 0.58 0.34 Example 4 5.68 0.60 0.28 .

[0028] Analysis of the relevant properties of the cast high-zirconium bricks in the examples shows that the bulk density of all examples is higher than 5.59 g / cm³, and the porosity is lower than 0.61%. This indicates that the material has extremely high density, and compared with traditional cast high-zirconium bricks (which typically have a porosity of around 1-2%), the porosity of the material of this invention is significantly reduced. This high density mainly originates from the reduction reaction mechanism of SnO2. The oxygen bubbles released by SnO2 merge and escape, reducing internal defects. High density means that the material is more compact and can better resist the penetration and erosion of molten glass.

[0029] Furthermore, the erosion rate of the high-zirconium bricks in all embodiments was below 0.34 mm / 24h, with Example 4 exhibiting the lowest erosion rate (0.28 mm / 24h). This indicates that the material possesses excellent erosion resistance in molten soda-lime glass at 1500℃. The low erosion rate is attributed to two factors: firstly, the high density reduces the intrusion path of the molten glass; secondly, the fine microstructure induced by La2O3 improves grain boundary stability and reduces the formation of the grain boundary glass phase. Traditional high-zirconium bricks are prone to decreased toughness and deteriorated thermal shock resistance due to their high ZrO2 content. This invention, through the introduction of La2Sn2O7, forms a fine and uniform microstructure, which can improve the fracture toughness and thermal shock resistance of the material.

[0030] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0031] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A high-temperature erosion-resistant cast high-zirconium brick, characterized in that... By mass fraction, it includes the following components: ZrO2: 96.4-97.6%, SiO2: 1.18-1.70%, Al2O3: 0.15-0.80%, Na2O: 0.04-0.08%, K2O: 0.02-0.06%, La2O3: 0.20-0.30%, SnO2: 0.20-0.30%, and other impurities less than 0.10%.

2. The high-temperature erosion-resistant cast high-zirconium brick as described in claim 1, characterized in that, The specific contents of each component in the high-temperature erosion-resistant cast high-zirconium brick are as follows: 97.13% ZrO2, 1.60% SiO2, 0.60% Al2O3, 0.06% Na2O, 0.04% K2O, 0.25% La2O3, 0.25% SnO2, and the contents of other components are less than 0.10%.

3. The high-temperature erosion-resistant cast high-zirconium brick as described in claim 1, characterized in that, The mass ratio of tin oxide to lanthanum oxide in the high-temperature corrosion-resistant cast high-zirconium brick is 1-1.1:

1.

4. A method for preparing high-temperature erosion-resistant cast high-zirconium bricks according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Take the corresponding raw materials according to the above high zirconium brick ratio, the raw materials include desilicationized zircon, silica source and La2Sn2O7; S2: The uniformly mixed raw materials are melted in an electric arc furnace to form a molten liquid; S3: The molten liquid is poured into a mold and solidified, then heat-treated and annealed to obtain the high-zirconium brick.

5. The method as described in claim 4, characterized in that: In step S3, the casting temperature is ≥1950 degrees Celsius and the casting rate is 10–50 kg / s.

6. The method as described in claim 4, characterized in that: The preparation method of La2Sn2O7 in step S1 is as follows: a. Dissolve the lanthanum and tin precursors in deionized water in stoichiometric ratio; b. Add a complexing agent, heat and stir to form a uniform sol, and heat to 300 degrees Celsius to obtain the precursor powder; c. Calcine the precursor powder to obtain La2Sn2O7.

7. The method as described in claim 6, characterized in that: In step a, the precursor of lanthanum is either lanthanum nitrate or lanthanum citrate, and the precursor of tin is tin chloride. The molar ratio of lanthanum to tin is 1:

1.

8. The method as described in claim 6, characterized in that: The complexing agent in step b is citric acid, and the molar ratio of citric acid to metal ions is 1-2:

1.

9. The method as described in claim 6, characterized in that: The specific conditions for calcination in step c are: calcination at 600-800 degrees Celsius for 2-4 hours.

10. The application of the high-temperature erosion-resistant cast high-zirconium bricks as described in any one of claims 1-3 in the field of glass furnaces.