Fused zirconia corundum and preparation method thereof

Abstract

The invention discloses fused zirconia corundum, which is prepared by melting zirconium oxychloride (ZrOCl. 8HO), nanoscale silica sol, sodium carbonate (NaCO) and yttrium oxide (YO). Yttrium oxide can effectively inhibit reversal of zirconium oxide from a tetragonal phase to a monoclinic phase, and product cracks caused by volume change are avoided. In terms of performance, the phase structure of yttrium-stabilized zirconium (YSZ) is more stable in a high-temperature corrosion environment, so that the service life of a product is prolonged. In addition, the product is not easy to crack in the kiln heating and using process, and the overall stability of the kiln can be improved. The problem of phase change cracking of the pure zirconium brick is solved through the stable synergistic effect of the sodium silicate glass phase and yttrium; yttrium oxide is directly introduced in a smelting method, and the agglomeration defect of a powder metallurgy method is avoided.

Description

Technical Field

[0001] This invention relates to the field of high-temperature resistant materials, and in particular to an electrofused zirconia alumina and its preparation method. Background Technology

[0002] Refractory bricks are designed for extreme environments, capable of withstanding temperatures of 1580℃-1770℃, and are widely used in metallurgy, glass manufacturing, cement kilns, and other applications. Their core characteristics include high temperature resistance, excellent thermal insulation, strong thermal shock resistance, and high chemical stability.

[0003] The main types include: Silicate-alumina refractory bricks: based on the Al2O3-SiO2 system, including silica bricks (containing over 93% SiO2, used in coke ovens and glass kilns) and clay bricks (Al2O3 content 30%-48%, refractoriness 1580℃-1750℃). High-alumina bricks: Al2O3 content 55%-85%, refractoriness exceeding 1770℃, apparent porosity 16%-22%, suitable for insulation layers in electric furnaces, heating furnaces, and other equipment. Lightweight insulating bricks: low thermal conductivity, high strength, bulk density 0.6-1.8 g / cm³, operating temperature 800℃-1600℃, can reduce the overall energy consumption of industrial furnaces and kilns by 15%-20%.

[0004] However, existing refractory bricks used in glass manufacturing furnaces have problems such as poor stability, easy cracking due to volume changes, or incompatibility between corrosion resistance and high-temperature stability. Summary of the Invention

[0005] The problem to be solved by this invention is to propose an innovative solution to address the shortcomings of the prior art, and in particular, a solution that can effectively solve the problem of balancing the high-temperature stability and corrosion resistance of refractory bricks.

[0006] To solve the above problems, the present invention adopts the following solution: an electrofused zirconia alumina, characterized in that the electrofused zirconia alumina is obtained by melting zirconium oxychloride ZrOCl2·8H2O, nano-sized silica sol, sodium carbonate Na2CO3, and yttrium oxide Y2O3, wherein the electrofused zirconia alumina has a zirconium content ≥48%, a silicon content ≥10.3%, a sodium content ≤1.05%, and a yttrium content ≤1%.

[0007] A method for preparing fused zirconia corundum, characterized by comprising the following steps: Raw material preparation: Prepare high-purity zirconium oxychloride (ZrOCl2·8H2O), with a zirconium content ≥48% and iron and aluminum impurities ≤0.1%; prepare nano-grade silica sol, with a SiO2 content of 20%~41%, and adjust the pH to neutral using acid and alkali methods; prepare sodium carbonate (Na2CO3), with a sodium content ≤1.05%; prepare yttrium oxide (Y2O3), with a purity ≥99%. Dispersion and mixing: Zirconium oxychloride and silica sol are mixed in proportion, and a small amount of dispersant is added to prevent agglomeration and ensure uniformity; sodium carbonate and yttrium oxide are added, and the mixture is wet-milled in a ball mill for 6 hours to control the particle size to D50≤1μm and reduce sintering defects; Melting: A vacuum arc furnace (VAR) is used, equipped with a copper crucible and a circulating water cooling system to avoid sodium volatilization pollution; Pre-melting stage: The temperature is increased to 1200℃ at 10℃ / min to remove moisture and gases; Main melting stage: The temperature is rapidly increased to 2400℃ and maintained for 30 minutes to ensure complete melting of the zirconium-silicon-yttrium system; Holding stage: The temperature is held at 1800℃ for 2 hours to promote the formation of a glassy phase from Na2O and SiO2, which is dispersed at the zirconium grain boundaries; Molding: The molten liquid is poured into a graphite mold and isostatic pressing is used at a pressure of 200MPa to obtain an initial blank and reduce internal stress; Sintering: The process is carried out sequentially: low-temperature sintering: the temperature is increased to 800℃ at a rate of 5℃ / min to eliminate residual stress; medium-temperature sintering: the temperature is held at 1200℃ for 4 hours to promote the formation of solid solution between Y2O3 and ZrO2 and suppress phase transformation; high-temperature sintering: the temperature is sintered at 1600℃ for 6 hours to allow the sodium silicate glass phase to uniformly coat the zirconium grains, improve thermal shock resistance, and finally obtain fused zirconium corundum.

[0008] Furthermore, the method for preparing the fused zirconia corundum is characterized in that the melting process is carried out under argon protection at a pressure of 0.1 MPa to prevent sodium oxidation and yttrium volatilization, and the vacuum degree is maintained at ≤5×10⁻³ Pa to reduce porosity and increase density.

[0009] The technical effects of this invention are as follows: The fused zirconium corundum of this application is prepared by melting zirconium oxychloride (ZrOCl2·8H2O), nano-sized silica sol, sodium carbonate (Na2CO3), and yttrium oxide (Y2O3). Yttrium oxide effectively inhibits the reverse transformation of zirconium oxide from the tetragonal phase to the monoclinic phase, preventing cracks in the product due to volume changes. In terms of performance, the phase structure of yttrium-stabilized zirconium (YSZ) is more stable in high-temperature corrosive environments, thereby improving the product's service life. Furthermore, the product is less prone to cracking during kiln firing and use, which also increases the overall stability of the kiln.

[0010] The fused zirconia corundum of this application is suitable for use in glass furnaces (such as float glass production lines) where it is resistant to sodium vapor corrosion; and as a lining for high-temperature reactors, utilizing the irradiation stability of yttrium. The synergistic effect of the sodium-silicon glass phase and yttrium stabilization solves the phase transformation cracking problem of pure zirconia bricks; the smelting method directly introduces yttrium oxide, avoiding the agglomeration defects of powder metallurgy.

[0011] The fused zirconia corundum of this application achieves a balance between high-temperature stability and corrosion resistance through elemental synergistic design, providing a new approach for refractory materials in extreme environments. Detailed Implementation

[0012] The present invention will now be described in further detail.

[0013] Example: A fused zirconia alumina, wherein the fused zirconia alumina is prepared by melting zirconium oxychloride (ZrOCl2·8H2O), nano-sized silica sol, sodium carbonate (Na2CO3), and yttrium oxide (Y2O3). The fused zirconia alumina contains zirconium content ≥48%, silicon content ≥10.3%, sodium content ≤1.05%, and yttrium content ≤1%.

[0014] A method for preparing fused zirconia alumina includes the following steps: Raw material preparation: Prepare high-purity zirconium oxychloride (ZrOCl2·8H2O), with zirconium content ≥48% and iron and aluminum impurity content ≤0.1%; prepare nano-grade silica sol, with SiO2 content 20%~41%, and adjust the pH to neutral by acid and alkali; prepare sodium carbonate (Na2CO3), with sodium content ≤1.05%; prepare yttrium oxide (Y2O3), with purity ≥99%.

[0015] Dispersion and mixing: Zirconium oxychloride and silica sol are mixed in proportion, and a small amount of dispersant is added to prevent agglomeration and ensure uniformity; sodium carbonate and yttrium oxide are added, and the mixture is wet-milled in a ball mill for 6 hours to control the particle size to D50≤1μm and reduce sintering defects.

[0016] Melting: A vacuum arc furnace (VAR) is used, equipped with a copper crucible and a circulating water cooling system to avoid sodium volatilization contamination; Pre-melting stage: The temperature is increased to 1200℃ at 10℃ / min to remove moisture and gases; Main melting stage: The temperature is rapidly increased to 2400℃ and maintained for 30 minutes to ensure complete melting of the zirconium-silicon-yttrium system; Heating stage: The temperature is held at 1800℃ for 2 hours to promote the formation of a glassy phase from Na2O and SiO2, which is dispersed at the zirconium grain boundaries; The entire melting process is carried out under argon protection at a pressure of 0.1MPa to prevent sodium oxidation and yttrium volatilization, and the vacuum degree is maintained at ≤5×10⁻³Pa to reduce porosity and increase density.

[0017] Molding: The molten liquid is poured into a graphite mold and isostatic pressing is used at a pressure of 200 MPa to obtain an initial blank and reduce internal stress.

[0018] Sintering: The process is carried out sequentially: low-temperature sintering: the temperature is increased to 800℃ at a rate of 5℃ / min to eliminate residual stress; medium-temperature sintering: the temperature is held at 1200℃ for 4 hours to promote the formation of solid solution between Y2O3 and ZrO2 and suppress phase transformation; high-temperature sintering: the temperature is sintered at 1600℃ for 6 hours to allow the sodium silicate glass phase to uniformly coat the zirconium grains, improve thermal shock resistance, and finally obtain fused zirconium corundum.

[0019] Phase structure stabilization Yttrium oxide (Y2O3) stabilizes the tetragonal phase to above 2200℃ through a solid solution strengthening mechanism, thus avoiding the volume expansion caused by monoclinic phase transformation.

[0020] Sodium silicate glass phase (Na2O-SiO2) fills the grain boundaries, reducing the coefficient of thermal expansion and matching the zirconium matrix (thermal conductivity 1.5 W / (m·K)).

[0021] High-temperature performance test Thermal shock resistance: No cracking after 10 water-cooling cycles at 1100℃, which is superior to traditional zircon bricks (which fail after 5 cycles).

[0022] Corrosion resistance: The corrosion depth in molten alkaline slag at 1600℃ is ≤0.5mm, and the silicon content of 10.3% effectively neutralizes sodium ion corrosion.

Claims

1. A fused zirconia corundum, characterized in that, The fused zirconium alumina is prepared by melting zirconium oxychloride (ZrOCl2·8H2O), nano-sized silica sol, sodium carbonate (Na2CO3), and yttrium oxide (Y2O3). The fused zirconium alumina contains ≥48% zirconium, ≥10.3% silicon, ≤1.05% sodium, and ≤1% yttrium.

2. The method for preparing fused zirconia alumina according to claim 1, characterized in that, Includes the following steps: Raw material preparation: Prepare high-purity zirconium oxychloride (ZrOCl2·8H2O), with a zirconium content ≥48% and iron and aluminum impurities ≤0.1%; prepare nano-grade silica sol, with a SiO2 content of 20%~41%, and adjust the pH to neutral using acid and alkali methods; prepare sodium carbonate (Na2CO3), with a sodium content ≤1.05%; prepare yttrium oxide (Y2O3), with a purity ≥99%. Dispersion and mixing: Zirconium oxychloride and silica sol are mixed in proportion, and a small amount of dispersant is added to prevent agglomeration and ensure uniformity; sodium carbonate and yttrium oxide are added, and the mixture is wet-milled in a ball mill for 6 hours to control the particle size to D50≤1μm and reduce sintering defects; Melting: A vacuum arc furnace (VAR) is used, equipped with a copper crucible and a circulating water cooling system to avoid sodium volatilization pollution; Pre-melting stage: The temperature is increased to 1200℃ at 10℃ / min to remove moisture and gases; Main melting stage: The temperature is rapidly increased to 2400℃ and maintained for 30 minutes to ensure complete melting of the zirconium-silicon-yttrium system; Holding stage: The temperature is held at 1800℃ for 2 hours to promote the formation of a glassy phase from Na2O and SiO2, which is dispersed at the zirconium grain boundaries; Molding: The molten liquid is poured into a graphite mold and isostatic pressing is used at a pressure of 200MPa to obtain an initial blank and reduce internal stress; Sintering: The process is carried out sequentially: low-temperature sintering: the temperature is increased to 800℃ at a rate of 5℃ / min to eliminate residual stress; medium-temperature sintering: the temperature is held at 1200℃ for 4 hours to promote the formation of solid solution between Y2O3 and ZrO2 and suppress phase transformation; high-temperature sintering: the temperature is sintered at 1600℃ for 6 hours to uniformly coat the zirconium grains with the sodium silicate glass phase, improve thermal shock resistance, and finally obtain fused zirconium corundum.

3. The method for preparing fused zirconia corundum according to claim 1, characterized in that, The melting process is carried out under argon protection at a pressure of 0.1 MPa to prevent sodium oxidation and yttrium volatilization. The vacuum degree is maintained at ≤5×10⁻³ Pa to reduce porosity and increase density.