Low glass phase exudation zirconia corundum brick and preparation method thereof
By introducing core-shell dopants and yttrium oxide and γ-alumina into zirconia-corundum bricks, the problems of glass melt erosion and hydration expansion of AZS products in the furnace flame space were solved, and the preparation of zirconia-corundum bricks with high strength and low glass phase exudation was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XINYI NEW MATERIALS (MAANSHAN) CO LTD
- Filing Date
- 2026-04-20
- Publication Date
- 2026-06-19
AI Technical Summary
Existing general-purpose AZS products have insufficient resistance to molten glass corrosion in the flame space of the melting furnace, and calcium oxide is prone to cracking and pulverization of materials during hydration reactions.
The material employs a core-shell dopant structure with flower-shaped nano-titanium dioxide as the core and calcium oxide as the shell. By generating CaTiO3 at the grain boundary pores, the calcium oxide concentration is reduced, thus avoiding hydration reactions. Yttrium oxide and γ-alumina are added as stabilizers and auxiliary sintering components to improve the mechanical strength and sintering density of the material.
It effectively avoids the hydration reaction of calcium oxide, improves the material's resistance to glass melt erosion and mechanical strength, reduces the amount of glass phase exudation, and enhances the material's heat aging resistance and thermal shock resistance.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of refractory materials technology, specifically to zirconium corundum bricks with low glass phase exudation and their preparation method. Background Technology
[0002] As the glass industry rapidly iterates towards high-end fields such as ultra-white, high borosilicate, and photovoltaics, the continuous optimization of melting furnace structures, the sustained increase in melting temperature, and the increasingly refined forming processes have placed more stringent, personalized, and differentiated demands on the performance of cast refractory materials. Currently, the research focus of cast zirconia-corundum (AZS) series products, which are widely used in glass melting furnaces, is mainly on reducing the overall glass phase content of the material, exploring the impact of oxidation degree on the glass phase properties, and improving the macroscopic distribution of the glass phase in the finished product. The core objective is to improve the material's resistance to molten glass erosion to meet the usage requirements of areas in direct contact with molten glass, such as the furnace walls and bottom. However, existing general-purpose AZS products have significant shortcomings in addressing the specific performance requirements of the flame space within the melting furnace, and have failed to develop targeted technical solutions.
[0003] Chinese patent application CN121651899A discloses a low-glass phase fused zirconia-corundum brick with a special structure and its preparation method. This invention uses zirconium oxide, silica, alumina, calcium oxide, and magnesium oxide as raw materials to give the product excellent properties of high glass phase exudation temperature and low exudation amount. However, in this scheme, the calcium ion radius in calcium oxide is relatively large and cannot be absorbed by oxygen. 2- When fully enclosed, the hydration reaction is quite intense upon contact with water. The hydration process, which generates Ca(OH)2, is accompanied by volume expansion, which can lead to cracking and pulverization of the material. Summary of the Invention
[0004] The purpose of this invention is to provide a zirconium corundum brick with low glass phase exudation and its preparation method. A core-shell dopant is used as a sintering aid. The core-shell dopant has a core-shell structure with flower-shaped nano-titanium dioxide as the core and calcium oxide as the shell. The CaTiO3 generated by the flower-shaped nano-titanium dioxide and calcium oxide at high temperature is located in the grain boundary pores, which reduces the concentration of calcium oxide. CaTiO3 is not easily hydrated, avoiding the hydration reaction of calcium ions with water vapor in the air to form calcium hydroxide, thus eliminating the volume expansion caused by hydration.
[0005] The objective of this invention can be achieved through the following technical solutions:
[0006] Zirconium-corundum bricks with low glass phase exudation, by mass parts, include the following components:
[0007] Zirconia 32-33.5 parts, γ-alumina 30-32 parts, sodium oxide 0.8-1 parts, silicon dioxide 8-10 parts, yttrium oxide 2-3 parts, boron alumina 0.2-0.5 parts, strontium carbonate 0.5-1 parts and core-shell dopant 0.8-1.1 parts.
[0008] Furthermore, the core-shell dopant is prepared through the following steps:
[0009] Step 1: Using tetrabutyl titanate as the titanium source, flower-shaped nano-titanium dioxide is produced by hydrothermal crystallization.
[0010] Step 2: Using flower-shaped nano-titanium dioxide as the core, calcium nitrate is uniformly adsorbed and deposited on its surface under stirring. At high temperature, calcium nitrate thermally decomposes to generate calcium oxide, which is then coated in situ on the surface of the flower-shaped nano-titanium dioxide to obtain a core-shell dopant.
[0011] Furthermore, the specific preparation steps for flower-shaped nano-titanium dioxide are as follows:
[0012] Tetrabutyl titanate and ethanol were added to a polytetrafluoroethylene hydrothermal reactor and stirred for 20-30 min at 20-25℃ and 500-600 r / min. Then, 0.1 mol / L NaOH solution was added to adjust the pH to 8-9. The mixture was then heated to 180-190℃ and reacted for 30-32 h. After centrifugation at 10000-12000 r / min for 4-6 min, the mixture was filtered. The product was washed 2-4 times with deionized water and dried under vacuum at 60-70℃ for 1-2 h to obtain flower-shaped nano-titanium dioxide.
[0013] Furthermore, the volume ratio of tetrabutyl titanate to ethanol is 20-40:700-800.
[0014] Furthermore, the specific preparation steps for core-shell dopants are as follows:
[0015] Flower-shaped nano-titanium dioxide and a 30-35% (w / w) calcium nitrate solution were added to a reaction vessel and stirred at 20-25℃ and 500-600 r / min for 3-4 h. After filtration, the product was washed 2-4 times with deionized water, dried under vacuum at 60-70℃ for 1-2 h, transferred to a muffle furnace, and heated to 600-620℃ at a heating rate of 5-7℃ / min for 1-2 h to obtain a core-shell dopant.
[0016] Furthermore, the ratio of flower-shaped nano-titanium dioxide to calcium nitrate solution is 2-3g: 30-40mL.
[0017] Furthermore, the specific preparation steps for zirconium-corundum bricks with low glass phase exudation are as follows:
[0018] The mixed molten liquid is poured into a mold and centrifuged at 80-100 r / min to remove air pores. Then, it is cooled to 1370-1380℃ at a rate of 20-30℃ / h and held for 85-90 min. It is then cooled to 1015-1020℃ at a rate of 40-50℃ / h and then to 460-470℃ at a rate of 20-30℃ / h. Finally, it is allowed to cool naturally to room temperature to obtain a zirconia-corundum brick with low glass phase exudation.
[0019] Furthermore, the specific steps for preparing the mixed molten liquid are as follows:
[0020] Zirconia, γ-alumina, sodium oxide, silicon dioxide, yttrium oxide, strontium carbonate, and core-shell dopants are stirred and mixed, ground and sieved to an average particle size of 80 μm, placed in a muffle furnace, and lightly sintered at 600-700℃ for 30-40 min. Then, it is transferred to a three-phase electric arc furnace and heated to 1890-1910℃ at a rate of 5-8℃ / min to melt, while simultaneously undergoing oxygen blowing treatment at 1.4-1.6 MPa to remove carbon and oxidize, resulting in a mixed molten liquid.
[0021] The beneficial effects of this invention are:
[0022] 1. The present invention relates to a low glass phase exudation zirconium corundum brick, which uses a core-shell dopant as a sintering aid. The core-shell dopant has a core-shell structure with flower-shaped nano-titanium dioxide as the core and calcium oxide as the shell. At high temperature, the flower-shaped nano-titanium dioxide reacts with calcium oxide to form CaTiO3, which is located in the grain boundary pores, reducing the concentration of calcium oxide. CaTiO3 is not easily hydrated, thus avoiding the hydration reaction of calcium ions with water vapor in the air to form calcium hydroxide, and eliminating the volume expansion caused by hydration.
[0023] 2. The flower-shaped nano-titanium dioxide of the present invention possesses a large specific surface area and a flower-like structure, enabling it to exert a template effect and guide CaAl... 12 O 19 Lamellar crystals grow in a directional manner to avoid disordered growth, CaAl 12 O 19 Lamellar crystals can synergistically improve the mechanical strength and toughness of zirconium corundum bricks through crack deflection and bridging.
[0024] 3. This invention incorporates yttrium oxide as a stabilizer to maintain the tetragonal phase of zirconia. However, the uneven distribution of yttrium oxide in the crystal easily leads to yttrium ion segregation. Under the corrosive action of an aqueous environment, the yttrium ion segregation caused by oxygen vacancies triggers a phase transition from the tetragonal to the monoclinic phase on the surface of the zirconia material. This phase transition causes volume expansion and generates microcracks. Water molecules further penetrate into the material through these microcracks, increasing the stress on the material. Meanwhile, γ-alumina, as an auxiliary sintering component, causes aluminum ions to segregate at the grain boundaries, forming a strongly bonded and stable complex with the oxygen vacancies of yttrium oxide. This restricts the migration of oxygen vacancies and simultaneously prevents yttrium ion segregation at grain boundaries.
[0025] 4. This invention uses γ-alumina as an auxiliary sintering component and a core-shell dopant as a sintering aid. Metastable γ-alumina can transform to a stable state during sintering, reducing its free energy and acting as an additional driving force for sintering. Aluminum ions dissolve in the zirconium oxide lattice to form vacancy defects, which can serve as a fast channel for atomic diffusion, thereby further reducing the sintering temperature of the powder and increasing the sintering density. Detailed Implementation
[0026] 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. 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.
[0027] Example 1: A method for preparing zirconium-corundum bricks with low glass phase exudation, comprising the following steps:
[0028] S1: Add 20 mL of tetrabutyl titanate and 700 mL of ethanol to a polytetrafluoroethylene hydrothermal reactor. Stir for 20 min at 20 °C and 500 r / min. Then add 0.1 mol / L NaOH solution to adjust the pH to 8. Heat to 180 °C and continue the reaction for 30 h. Centrifuge at 10000 r / min for 4 min, filter, wash the product twice with deionized water, and vacuum dry at 60 °C for 1 h to obtain flower-shaped nano-titanium dioxide with an average particle size of 500 nm.
[0029] S2: Add 2g of flower-shaped nano-titanium dioxide and 30mL of 30% calcium nitrate solution to the reactor, stir for 3h at 20℃ and 500r / min, filter, wash the product twice with deionized water, vacuum dry at 60℃ for 1h, transfer to a muffle furnace, heat to 600℃ at a heating rate of 5℃ / min, and hold for 1h to obtain the core-shell dopant.
[0030] S3: Mix 32g zirconium oxide, 30g γ-alumina, 0.8g sodium oxide, 8g silicon dioxide, 2g yttrium oxide, 0.2g boron alumina, 0.5g strontium carbonate, and 0.8g core-shell dopant. Grind and sieve to an average particle size of 80μm. Place the mixture in a muffle furnace and lightly sinter at 600℃ for 30min. Then transfer it to a three-phase electric arc furnace and heat it to 1890℃ at a rate of 5℃ / min to melt it. Simultaneously, perform oxygen blowing treatment at 1.4MPa to remove carbon and oxidize the mixture, resulting in a mixed molten liquid.
[0031] S4: Pour the mixed molten liquid into a mold, centrifuge it at 80 r / min to remove air pores, then cool it to 1370℃ at a rate of 20℃ / h, hold it at that temperature for 85 min, cool it to 1015℃ at a rate of 40℃ / h, and then cool it to 460℃ at a rate of 20℃ / h. Allow it to cool naturally to room temperature to obtain a zirconia-corundum brick with low glass phase exudation.
[0032] Example 2: A method for preparing zirconium-corundum bricks with low glass phase exudation, comprising the following steps:
[0033] S1: Add 30 mL of tetrabutyl titanate and 750 mL of ethanol to a polytetrafluoroethylene hydrothermal reactor. Stir for 25 min at 22.5 °C and 550 r / min. Then add 0.1 mol / L NaOH solution to adjust the pH to 8.5. Heat to 185 °C and continue the reaction for 31 h. Centrifuge at 11000 r / min for 5 min, filter, wash the product three times with deionized water, and vacuum dry at 65 °C for 1.5 h to obtain flower-shaped nano-titanium dioxide with an average particle size of 500 nm.
[0034] S2: 2.5g of flower-shaped nano-titanium dioxide and 35mL of 32.5% calcium nitrate solution were added to the reactor and stirred at 22.5℃ and 550r / min for 3.5h. After filtration, the product was washed three times with deionized water, dried under vacuum at 65℃ for 1.5h, transferred to a muffle furnace, heated to 610℃ at a heating rate of 6℃ / min, and held for 1.5h to obtain the core-shell dopant.
[0035] S3: Mix 32.75g zirconium oxide, 31g γ-alumina, 0.9g sodium oxide, 9g silicon dioxide, 2.5g yttrium oxide, 0.35g boron alumina, 0.75g strontium carbonate and 0.95g core-shell dopant, grind and sieve to an average particle size of 80μm, place in a muffle furnace, lightly sinter at 650℃ for 35min, then transfer to a three-phase electric arc furnace, heat to 1900℃ at a rate of 7℃ / min to melt, and simultaneously perform oxygen blowing treatment at 1.5MPa to remove carbon and oxidize, to obtain a mixed molten liquid.
[0036] S4: Pour the mixed molten liquid into a mold, centrifuge it at 90 r / min to remove air pores, then cool it to 1375℃ at a rate of 25℃ / h, hold it at that temperature for 87.5 min, cool it to 1017.5℃ at a rate of 45℃ / h, and then cool it to 465℃ at a rate of 25℃ / h. Allow it to cool naturally to room temperature to obtain a zirconia-corundum brick with low glass phase exudation.
[0037] Example 3: A method for preparing zirconium-corundum bricks with low glass phase exudation, comprising the following steps:
[0038] S1: Add 40 mL of tetrabutyl titanate and 800 mL of ethanol to a polytetrafluoroethylene hydrothermal reactor. Stir for 30 min at 25 °C and 600 r / min. Then add 0.1 mol / L NaOH solution to adjust the pH to 9. Heat to 190 °C and continue the reaction for 32 h. Centrifuge at 12000 r / min for 6 min, filter, wash the product 4 times with deionized water, and vacuum dry at 70 °C for 2 h to obtain flower-shaped nano-titanium dioxide with an average particle size of 500 nm.
[0039] S2: Add 3g of flower-shaped nano-titanium dioxide and 40mL of 35% calcium nitrate solution to the reactor, stir at 25℃ and 600r / min for 4h, filter, wash the product with deionized water 4 times, vacuum dry at 70℃ for 2h, transfer to muffle furnace, heat to 620℃ at a heating rate of 7℃ / min, hold for 2h to obtain core-shell dopant.
[0040] S3: Mix 33.5g zirconium oxide, 32g γ-alumina, 1g sodium oxide, 10g silicon dioxide, 3g yttrium oxide, 0.5g alumina boron, 1g strontium carbonate, and 1.1g core-shell dopant, grind and sieve to an average particle size of 80μm, place in a muffle furnace, and lightly sinter at 700℃ for 40min. Then transfer to a three-phase electric arc furnace and heat to 1910℃ at a rate of 8℃ / min to melt, while simultaneously performing oxygen blowing treatment at 1.6MPa to remove carbon and oxidize, to obtain a mixed molten liquid.
[0041] S4: Pour the mixed molten liquid into a mold, centrifuge it at 100 r / min to remove air pores, then cool it to 1380℃ at a rate of 30℃ / h, hold it at that temperature for 90 min, cool it to 1020℃ at a rate of 50℃ / h, and then cool it to 470℃ at a rate of 30℃ / h. Allow it to cool naturally to room temperature to obtain a zirconia-corundum brick with low glass phase exudation.
[0042] Comparative Example 1: Based on Example 3, the core-shell dopant in step S3 was replaced with an equal mass of calcium oxide, while the other steps remained unchanged, to prepare a zirconium corundum brick with low glass phase exudation.
[0043] Comparative Example 2: Based on Example 3, γ-alumina in step S3 was replaced with α-alumina, while the other steps remained unchanged, to prepare zirconia-corundum bricks with low glass phase exudation.
[0044] Comparative Example 3: Based on Example 3, the flower-shaped nano-titanium dioxide in step S2 was replaced with commercially available titanium dioxide microspheres with a particle size of 500 nm, while the other steps remained unchanged, to prepare a zirconium corundum brick with low glass phase exudation.
[0045] Performance tests were conducted on the low glass phase exudation zirconia-corundum bricks prepared in Examples 1-3 and Comparative Examples 1-3. The glass phase exudation was tested according to JC / T 493-2015 "Fused Cast Zirconia-Corundum Refractory Products for Glass Melting Furnaces"; the compressive strength was tested according to GB / T 5072-2023 "Test Method for Compressive Strength of Refractory Materials at Room Temperature". The samples were then placed at 60℃ and 90%RH for 500 hours, and the compressive strength was tested again to reflect heat aging resistance. Thermal shock resistance was tested by placing the samples in a resistance furnace and holding them at 1100℃ for 20 minutes, then rapidly cooling them in cold water for 5 minutes, placing them in air for 5 minutes, and then placing them back in the resistance furnace for 5 minutes. This process was repeated 10 times. The results are shown in Table 1.
[0046] Table 1 Performance Test Table for Zirconium-Corundum Bricks with Low Glass Phase Emission
[0047]
[0048] As shown in Table 1, the free calcium oxide in Comparative Example 1 is in an unconstrained free state. During the melting process, it preferentially reacts with silicon dioxide and sodium oxide in the system to generate a large amount of low-melting-point sodium-calcium-silicon glass phase, which significantly reduces the initial precipitation temperature and high-temperature viscosity of the glass phase. The free calcium oxide is randomly distributed and locally enriched in the system, and cannot achieve uniform dispersion of calcium ions. The lamellar crystals generated in situ at high temperature are uneven in size and severely agglomerated, and cannot play a uniform crack deflection and bridging toughening role. At the same time, without the support of titanium oxide core, it cannot generate CaTiO3 to fill the grain boundary pores. The free calcium oxide is very easy to react with water vapor in the air to generate calcium hydroxide, accompanied by significant volume expansion, generating a large number of microcracks inside the material, causing irreversible structural deterioration.
[0049] In Comparative Example 2, α-alumina is a thermodynamically stable crystalline phase. During sintering, there is no free energy drop from the γ-α phase transformation to provide additional sintering driving force. Furthermore, the lack of rapid atomic diffusion channels due to lattice defects in metastable γ-alumina significantly reduces the sintering activity of the powder, leading to increased grain boundary porosity and the formation of numerous interconnected channels for glassy phase exudation. The absence of aluminum ion grain boundary segregation due to lattice distortion in α-alumina prevents the formation of a strongly bonded stable complex with oxygen vacancies in yttrium oxide, thus failing to limit oxygen vacancy migration and yttrium ion grain boundary segregation. Under humid and hot conditions, yttrium ion segregation triggers a phase transformation from tetragonal to monoclinic in zirconia, generating numerous microcracks within the material.
[0050] In Comparative Example 3, the commercially available titanium dioxide microspheres have a solid, dense structure with a surface area far lower than that of hierarchical porous flower-shaped nano-titanium dioxide. During the impregnation process with calcium nitrate solution, they cannot provide sufficient active sites to adsorb calcium ions, resulting in insufficient calcium salt loading, uneven coating, and the inability to form a complete and continuous calcium oxide shell, leading to complete failure of the core-shell structure. Due to the uneven coating of the core-shell structure, the calcium hexaaluminate lamellars generated in situ at high temperatures are unevenly distributed and locally agglomerated, failing to exert uniform crack deflection and bridging toughening effects. The calcium oxide shell coating is incomplete, with a large number of calcium ions existing in a free state, which easily undergoes hydration reactions with water vapor, causing volume expansion and microcracks.
[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.
Claims
1. A zirconium-corundum brick with low glass phase exudation, characterized in that, By mass parts, it includes the following components: Zirconia 32-33.5 parts, γ-alumina 30-32 parts, sodium oxide 0.8-1 parts, silicon dioxide 8-10 parts, yttrium oxide 2-3 parts, boron alumina 0.2-0.5 parts, strontium carbonate 0.5-1 parts, and core-shell dopant 0.8-1.1 parts; The core-shell dopant is prepared through the following steps: Using flower-shaped nano-titanium dioxide as the core, calcium nitrate is uniformly adsorbed and deposited on its surface under stirring. At high temperature, calcium nitrate thermally decomposes to generate calcium oxide, which is then coated in situ onto the surface of the flower-shaped nano-titanium dioxide, thus obtaining a core-shell dopant.
2. The low glass phase exudation zirconium-corundum brick according to claim 1, characterized in that, The specific preparation steps for the flower-shaped nano-titanium dioxide are as follows: Tetrabutyl titanate and ethanol were added to a polytetrafluoroethylene hydrothermal reactor and stirred for 20-30 min at 20-25℃ and 500-600 r / min. Then, 0.1 mol / L NaOH solution was added to adjust the pH to 8-9. The mixture was then heated to 180-190℃ and reacted for 30-32 h. After centrifugation at 10000-12000 r / min for 4-6 min, the mixture was filtered. The product was washed 2-4 times with deionized water and dried under vacuum at 60-70℃ for 1-2 h to obtain flower-shaped nano-titanium dioxide.
3. The low glass phase exudation zirconium-corundum brick according to claim 2, characterized in that, The volume ratio of tetrabutyl titanate to ethanol is 20-40:700-800.
4. The low glass phase exudation zirconium-corundum brick according to claim 1, characterized in that, The specific preparation steps for the core-shell dopant are as follows: Flower-shaped nano-titanium dioxide and calcium nitrate solution were added to a reaction vessel and stirred for 3-4 hours at 20-25℃ and 500-600 r / min. After filtration, the product was washed 2-4 times with deionized water, dried under vacuum at 60-70℃ for 1-2 hours, transferred to a muffle furnace, heated to 600-620℃ at a heating rate of 5-7℃ / min, and held for 1-2 hours to obtain a core-shell dopant.
5. The low glass phase exudation zirconium-corundum brick according to claim 4, characterized in that, The calcium nitrate solution has a mass fraction of 30-35%.
6. The low glass phase exudation zirconium-corundum brick according to claim 4, characterized in that, The ratio of the flower-shaped nano-titanium dioxide to the calcium nitrate solution is 2-3g:30-40mL.
7. A method for preparing zirconium-corundum bricks with low glass phase exudation, characterized in that, The specific preparation steps for the low glass phase exudation zirconium-corundum brick are as follows: The mixed molten liquid is poured into a mold and centrifuged at 80-100 r / min to remove air pores. Then, it is cooled to 1370-1380℃ at a rate of 20-30℃ / h and held for 85-90 min. It is then cooled to 1015-1020℃ at a rate of 40-50℃ / h and then to 460-470℃ at a rate of 20-30℃ / h. Finally, it is allowed to cool naturally to room temperature to obtain a zirconia-corundum brick with low glass phase exudation.
8. The method for preparing zirconium-corundum bricks with low glass phase exudation according to claim 7, characterized in that, The specific preparation steps of the mixed molten liquid are as follows: Zirconia, γ-alumina, sodium oxide, silicon dioxide, yttrium oxide, strontium carbonate, and core-shell dopants were stirred and mixed, ground and sieved to an average particle size of 80 μm, placed in a muffle furnace, and lightly sintered at 600-700℃ for 30-40 min. Then, the mixture was transferred to a three-phase electric arc furnace, heated to 1890-1910℃ to melt, and simultaneously subjected to oxygen blowing treatment to remove carbon and oxidize, resulting in a mixed molten liquid.
9. The method for preparing zirconium-corundum bricks with low glass phase exudation according to claim 8, characterized in that, The heating rate is 5-8°C / min.
10. The method for preparing zirconium-corundum bricks with low glass phase exudation according to claim 8, characterized in that, The oxygen pressure for the oxygen blowing treatment is 1.4-1.6 MPa.