High-zirconium brick suitable for TFT (Thin Film Transistor) glass channel and preparation process thereof

Abstract

The invention belongs to the technical field of refractory materials, and particularly relates to a high-zirconium brick suitable for a TFT glass channel and a preparation process of the high-zirconium brick. The tin oxide and the yttrium oxide are added into a casting system to serve as modifiers, the tin oxide is introduced into the system in a partial pre-doping mode, the pre-doped tin oxide can be evenly distributed in a zirconium oxide system, the microcosmic uniformity of the tin oxide in the casting high-zirconium brick is improved, and the thermal conductivity of the high-zirconium brick is improved. Furthermore, the grain size and distribution consistency of the system are reduced by utilizing the performance of tin oxide, so that the strength, hardness and fracture toughness of the high-zirconium brick are improved. In addition, tin oxide which is not doped in the system generates oxygen under the action of a reducing atmosphere in the contact process of casting liquid and a graphite casting mold, and the oxygen can gather and take away tiny bubbles which are difficult to remove, so that the density of the cast high-zirconium brick is improved to a certain extent, and the erosion resistance of the cast high-zirconium brick is remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of refractory materials, and particularly relates to a high-zirconia brick suitable for a TFT glass channel and a preparation process thereof. BACKGROUND

[0002] In the flat panel display industry, especially in the TFT-LCD field, the quality requirements for glass substrates are extremely strict, and the glass substrates are required to have high flatness, low defects, high chemical stability and excellent internal quality. These glasses are usually melted at high temperature and then transported and formed through specific channels (such as a molten tin tank, a refining and homogenizing channel, a feeding channel and the like). The lining refractory material of the channel directly contacts with the high-temperature and high-chemical-activity glass liquid, and the performance of the lining refractory material directly determines the quality of the final glass product and the operation efficiency and cost of the production line.

[0003] The TFT glass is usually alkali-free or low-alkali aluminosilicate glass, and the melting temperature of the glass is high, usually higher than 1650℃, and the chemical corrosion is strong, which puts extremely high challenges on the corrosion resistance, penetration resistance and high-temperature stability of the refractory material. At the key parts of the channel, such as the side wall and the bottom directly contacting with the glass liquid, once the refractory material is eroded, the glass liquid will be contaminated and bubbles will be formed.

[0004] To fundamentally solve the above problems, the industry has turned its attention to high zirconia content cast high zirconia bricks. High zirconia bricks significantly reduce the glass phase content by significantly increasing the ZrO2 content to more than 80%, thereby theoretically having the huge potential of stronger resistance to corrosion and less pollution to glass liquid. However, the development and application of high zirconia cast bricks itself also faces a series of severe technical challenges: such as the stability problem of zirconia phase transition: zirconia will undergo reversible transformation between monoclinic, tetragonal and cubic crystal forms during heating and cooling, accompanied by significant volume change (about 3%-5%). This volume effect is extremely easy to produce huge internal stress in the brick body, resulting in cracking, pulverization or even structural collapse of the brick body during sintering or use. The existing technology usually uses the addition of stabilizers (such as CaO, MgO, Y2O3) to inhibit the phase transition, such as the prior art CN112979292 A discloses a preparation method of a low-leaching electrically fused zirconia corundum brick with yttrium oxide added. The invention fully retains the original advantages of the electrically fused zirconia corundum brick, has a simple process, and can produce products with good performance. The invention innovatively introduces yttrium oxide into the electrically fused zirconia corundum brick, not only in the raw material, but also in the surface of the finished product, and industrial alumina and magnesium oxide are added to the raw material composition, and the purity and content of zirconia are improved, which greatly improves the initial precipitation temperature of the glass phase, and the glass phase produced in the production of high borosilicate glass is extremely little, which increases the clarity of the produced high borosilicate glass, solves the problems of easy cracking, corrosion and glass pollution in production, and is more beneficial to the production of medium and high borosilicate glass. However, on the one hand, the anti-erosion performance of the high zirconia brick prepared by the prior art needs to be further improved, and on the other hand, the introduction of bubbles in the whole process from raw material to melting and casting in the existing casting process will significantly reduce the density of the brick body, becoming a weak link of resistance to glass liquid erosion, seriously affecting the service life and safety in the TFT glass channel.

[0005] In summary, the high zirconia brick in the prior art cannot meet the ultra-high requirements of the TFT glass channel due to the glass phase exudation, inherent phase change problem and insufficient corrosion resistance. Therefore, there is an urgent need in the art for a new type of high zirconia cast brick with scientific component design, stable phase structure and controllable preparation process, to overcome the above technical barriers and provide a high-performance channel refractory solution for the TFT glass industry. SUMMARY

[0006] To solve the technical problems in the background art, the present application provides a high zirconia brick suitable for TFT glass channel and its preparation process, which can give the high zirconia cast brick more excellent corrosion resistance by adding tin oxide in the casting system and cooperating with a specific addition method of tin oxide.

[0007] An object of the present application is to provide a high-zirconia brick suitable for TFT glass channel, characterized in that the high-zirconia brick comprises the following components in mass fraction: 96.3-97.7% of ZrO2, 1.18-1.94% of SiO2, 0.15-0.98% of Al2O3, 0.04-0.08% of Na2O, 0.02-0.06% of K2O, 0.21-0.29% of Y2O3, 0.68-0.92% of SnO2, and the content of other components is less than 0.13%.

[0008] Further, the mass ratio of Y2O3 to SnO2 is 1:3-5.

[0009] The present application simultaneously uses Y2O3 and SnO2 in the fused cast high-zirconia brick, Y2O3 is solid-solved into the ZrO2 crystal lattice, inhibits the destructive phase transition from tetragonal phase to monoclinic phase during cooling process, ensures that the product body is stable tetragonal phase and cubic phase, thereby obtaining excellent thermal shock stability and volume stability. SnO2 is limitedly solid-solved with ZrO2 at high temperature, can balance the structural stability and sintering densification power, and maximally improves the comprehensive performance of the fused cast high-zirconia brick.

[0010] Another object of the present application is to provide a preparation method of the high-zirconia brick suitable for TFT glass channel, characterized in that the method comprises the following steps: S1: taking desiliconized zircon, SiO2, Al2O3, Na2O, K2O, Y2O3 and SnO2 according to the above high-zirconia brick ratio; taking part of SnO2, pre-doping the SnO2 with the desiliconized zircon to obtain SnO2 pre-doped desiliconized zircon.

[0011] S2: uniformly mixing the SnO2 pre-doped desiliconized zircon in step S1 with the remaining components to obtain a mixture; heating and melting the mixture in an electric arc furnace to obtain a molten liquid; S3: casting the molten liquid into a mold to solidify, annealing and processing to obtain the high-zirconia brick.

[0012] Further, the tin oxide used for doping the desiliconized zircon in step S1 accounts for 60-80% of the total amount of tin oxide.

[0013] Further, the casting temperature in step S3 is ≥1950°C, and the casting rate is 10-50 kg / s.

[0014] Further, the specific process of doping the desiliconized zircon with tin oxide in step S1 is as follows: a. mixing the desiliconized zircon and tin oxide according to the above ratio, and placing the mixed raw materials, zirconia grinding balls and anhydrous ethanol in a ball mill tank for ball milling.

[0015] b, after drying, placed in a high-temperature sintering furnace, heated to 1450-1550 DEG C in air atmosphere, heat preservation, and then with the furnace cooling to room temperature, namely the tin oxide doped desilicon zirconium oxide is obtained.

[0016] Further, the ball-to-material ratio (5-10):1 in the ball milling process in step a.

[0017] Further, the ball milling time in step a is 12-48 hours, and the D50 particle size of the mixed powder is less than 0.8 microns after ball milling.

[0018] This step effectively breaks the agglomeration of zirconium oxide particles by high-energy mechanical force, and makes SnO2 nanoparticles uniformly adhere to the surface of ZrO2 particles, achieving uniform mixing at the molecular level. Refining the powder D50 to submicron level can greatly increase the sintering activity of the powder, reduce the subsequent sintering temperature, and lay the foundation for obtaining a fine-grained microstructure.

[0019] Further, the heating rate in step b is 3-5 DEG C / min.

[0020] Further, the holding time in step b is 2-6 hours.

[0021] At a temperature close to the melting point of ZrO2, uniformly distributed SnO2 partially dissolves with the ZrO2 matrix, and forms a trace amount of transient liquid phase at the grain boundary. This liquid phase greatly promotes the diffusion mass transfer and grain rearrangement, thereby achieving rapid densification at a temperature much lower than the densification temperature of pure ZrO2. The subsequent holding process makes the liquid phase disappear due to continuous solid solution, and finally an almost glass-free, clean grain boundary fully solid solution structure is obtained after cooling, which makes the material have high density and excellent high temperature performance.

[0022] The present application has the following beneficial effects: 1. In the present application, tin oxide and yttrium oxide are used to modify the melting and casting high zirconia brick. Yttrium oxide can be solid-solved into the ZrO2 lattice, inhibit the destructive phase transition from tetragonal to monoclinic during cooling process, ensure that the product is stable tetragonal and cubic phase, thereby obtaining excellent thermal shock stability and volume stability. SnO2 can be limited to solid solution with ZrO2 at high temperature, which can balance the structural stability and sintering densification power, and maximize the comprehensive performance of the melting and casting high zirconia brick.

[0023] 2. In the present application, part of the tin oxide is introduced into the system by pre-doping. The pre-doped tin oxide can be uniformly distributed in the zirconia system, improve the micro-uniformity of tin oxide in the melting and casting high zirconia brick, reduce the grain size and distribution consistency of the system by using the performance of tin oxide, and further improve the strength, hardness and fracture toughness of the high zirconia brick.

[0024] 3. In cast high-zirconium bricks, pre-doped tin oxide preferentially reacts with SiO2 to form SnSiO4. This process consumes the invading SiO2, preventing it from reacting with the main ZrO2 matrix, thus protecting the ZrO2 matrix from silicification and hindering zircon crystal formation. The generated SnSiO4 is thermodynamically very stable and does not introduce internal stress due to phase transformation volume effects. Furthermore, it is distributed in the form of small, isolated crystals at grain boundaries or in the matrix, acting as grain boundary pinning agents and inhibiting excessive grain growth, which is beneficial for refining the microstructure. In addition, the glass phase has an open structure and high ion mobility. Sodium and potassium ions mainly migrate through the glass phase at high temperatures. As SiO2 is consumed, the amount of glass phase in the system decreases accordingly, further reducing the migration channels for sodium and potassium ions and mitigating the problem of glass melt contamination caused by ion diffusion to some extent.

[0025] 4. During the casting process, as the temperature decreases, the viscosity of the casting liquid continuously increases. The gases generated during the melting and casting stage and those entrained during the casting process are difficult to expel. The presence of these gases significantly affects the density of the cast high-zirconium bricks. By directly adding a certain amount of tin oxide to the system, the tin oxide in the system generates oxygen under the action of a reducing atmosphere during the contact between the casting liquid and the graphite mold. This oxygen can gather and carry away these difficult-to-remove microbubbles, thereby improving the density of the cast high-zirconium bricks to a certain extent and significantly improving their corrosion resistance. Attached Figure Description

[0026] Figure 1 The diagram shows a comparison of the bulk density of cast high-zirconium bricks used in the examples and comparative examples. Figure 2 Comparison of porosity between the examples and comparative examples of cast high-zirconium bricks; Figure 3 The graph shows a comparison of the glass melt erosion rates of the fused high zirconium bricks used in the examples and comparative examples. Detailed Implementation

[0027] 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.

[0028] It should be noted that the specific process of tin oxide doping desiliconized zircon in the following embodiments and comparative examples is as follows. The specific difference lies in the different doping amounts of tin oxide in the different embodiments and comparative examples. For details, please refer to each embodiment and comparative example, which will not be repeated here.

[0029] According to the corresponding proportion, the desilicated zircon and tin oxide are mixed, the mixed raw materials, grinding balls and anhydrous ethanol are placed in a ball mill tank for ball milling, the ball-to-material ratio is 8:1, and the ball milling is performed for 24 hours until the D50 particle size of the mixed powder is less than 0.8 μm; after drying, the mixture is placed in a high-temperature sintering furnace, heated to 1500 ℃ at a temperature rising rate of 5 ℃ / min in an air atmosphere, and kept for 4 hours, and then cooled to room temperature in the furnace to obtain the desilicated zircon doped with tin oxide. Example 1

[0030] 96.63% of ZrO2, 1.94% of SiO2, 0.15% of Al2O3, 0.08% of Na2O, 0.02% of K2O, 0.21% of Y2O3, 0.88% of SnO2, and the content of other components is less than 0.13%.

[0031] According to the above high-zirconia brick, the desilicated zircon, SiO2, Al2O3, Na2O, K2O, Y2O3 and SnO2 are taken; 60% of the total amount of SnO2 is taken as tin oxide, which is pre-doped with desilicated zircon to obtain SnO2 pre-doped desilicated zircon. The SnO2 pre-doped desilicated zircon and the remaining components are mixed uniformly to obtain a mixture; the mixture is heated and melted in an electric arc furnace to obtain a molten liquid; the molten liquid is cast into a mold at a casting temperature of ≥1950 ℃ and a casting rate of 10-50 kg / s, solidified, annealed, and processed to obtain the high-zirconia brick. Example 2

[0032] 96.63% of ZrO2, 1.94% of SiO2, 0.15% of Al2O3, 0.08% of Na2O, 0.02% of K2O, 0.21% of Y2O3, 0.88% of SnO2, and the content of other components is less than 0.13%.

[0033] According to the above high-zirconia brick, the desilicated zircon, SiO2, Al2O3, Na2O, K2O, Y2O3 and SnO2 are taken; 60% of the total amount of SnO2 is taken as tin oxide, which is pre-doped with desilicated zircon to obtain SnO2 pre-doped desilicated zircon. The SnO2 pre-doped desilicated zircon and the remaining components are mixed uniformly to obtain a mixture; the mixture is heated and melted in an electric arc furnace to obtain a molten liquid; the molten liquid is cast into a mold at a casting temperature of ≥1950 ℃ and a casting rate of 10-50 kg / s, solidified, annealed, and processed to obtain the high-zirconia brick.

[0034] Example 3 97.5% of ZrO2, 1.18% of SiO2, 0.15% of Al2O3, 0.04% of Na2O, 0.03% of K2O, 0.28% of Y2O3, 0.71% of SnO2, and the content of other components is less than 0.13%.

[0035] According to the above high zirconium brick ratio take desiliconized zircon, SiO2, Al2O3, Na2O, K2O, Y2O3 and SnO2; take the total amount of SnO2 60% of tin oxide, which is pre-doped with desiliconized zircon, and SnO2 pre-doped desiliconized zircon is obtained. Mix the SnO2 pre-doped desiliconized zircon with the remaining components to obtain a mixture; heat and melt in an electric arc furnace to obtain a molten liquid; pour the molten liquid into the mold at a pouring temperature ≥ 1950 degrees Celsius, a pouring rate of 10-50 kg / s, solidify, anneal, and process to obtain the high zirconium brick. 97.5% of ZrO2, 1.18% of SiO2, 0.15% of Al2O3, 0.04% of Na2O, 0.03% of K2O, 0.28% of Y2O3, 0.71% of SnO2, and the content of other components is less than 0.13%.

[0036] According to the above high zirconium brick ratio take desiliconized zircon, SiO2, Al2O3, Na2O, K2O, Y2O3 and SnO2; take the total amount of SnO2 60% of tin oxide, which is pre-doped with desiliconized zircon, and SnO2 pre-doped desiliconized zircon is obtained. Mix the SnO2 pre-doped desiliconized zircon with the remaining components to obtain a mixture; heat and melt in an electric arc furnace to obtain a molten liquid; pour the molten liquid into the mold at a pouring temperature ≥ 1950 degrees Celsius, a pouring rate of 10-50 kg / s, solidify, anneal, and process to obtain the high zirconium brick. 97.5% of ZrO2, 1.18% of SiO2, 0.15% of Al2O3, 0.04% of Na2O, 0.03% of K2O, 0.28% of Y2O3, 0.71% of SnO2, and the content of other components is less than 0.13%.

[0037] According to the above high zirconium brick ratio take desiliconized zircon, SiO2, Al2O3, Na2O, K2O, Y2O3 and SnO2; take the total amount of SnO2 60% of tin oxide, which is pre-doped with desiliconized zircon, and SnO2 pre-doped desiliconized zircon is obtained. Mix the SnO2 pre-doped desiliconized zircon with the remaining components to obtain a mixture; heat and melt in an electric arc furnace to obtain a molten liquid; pour the molten liquid into the mold at a pouring temperature ≥ 1950 degrees Celsius, a pouring rate of 10-50 kg / s, solidify, anneal, and process to obtain the high zirconium brick. 97.5% of ZrO2, 1.18% of SiO2, 0.15% of Al2O3, 0.04% of Na2O, 0.03% of K2O, 0.28% of Y2O3, 0.71% of SnO2, and the content of other components is less than 0.13%.

[0038] According to the above-mentioned proportions for high-zirconium bricks, desilicationized zircon, SiO2, Al2O3, Na2O, K2O, Y2O3, and SnO2 are taken; tin oxide accounting for 50% of the total SnO2 is taken and pre-doped with the desilicationized zircon to obtain SnO2-predoped desilicationized zircon. The SnO2-predoped desilicationized zircon is mixed evenly with the remaining components to obtain a mixture; it is heated and melted in an electric arc furnace to obtain a 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 then processed to obtain the high-zirconium bricks. It contains 97.5% ZrO2, 1.18% SiO2, 0.15% Al2O3, 0.04% Na2O, 0.03% K2O, 0.28% Y2O3, and 0.71% SnO2, with other components comprising less than 0.13%.

[0039] According to the above-mentioned proportions for high-zirconium bricks, desilicationized zircon, SiO2, Al2O3, Na2O, K2O, Y2O3, and SnO2 are taken; tin oxide, accounting for 85% of the total SnO2, is taken and pre-doped with the desilicationized zircon to obtain SnO2-predoped desilicationized zircon. The SnO2-predoped desilicationized zircon is mixed evenly with the remaining components to obtain a mixture; it is heated and melted in an electric arc furnace to obtain a 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 then processed to obtain the high-zirconium bricks. It contains 97.5% ZrO2, 1.18% SiO2, 0.15% Al2O3, 0.04% Na2O, 0.03% K2O, 0.28% Y2O3, and 0.71% SnO2, with other components comprising less than 0.13%.

[0040] According to the above-mentioned proportions for high-zirconium bricks, desilicationized zircon, SiO2, Al2O3, Na2O, K2O, Y2O3 and SnO2 are mixed evenly to obtain a mixture; the mixture is heated and melted in an electric arc furnace to obtain a 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, and then annealed and processed to obtain the high-zirconium bricks. Performance characterization: The apparent porosity and bulk density of six samples taken from each standard brick sample were tested according to GB / T2997-2015. The static resistance to glass melt erosion (mm / 24h) was measured according to standard JC / T806-2013 under ordinary soda-lime glass melt conditions at 1500℃. The relevant properties of the cast high-zirconium bricks in the examples and comparative examples are shown in the table below.

[0041] Examples Bulk density (g / cm -3 ) Porosity (%) Resistance to glass corrosion rate (mm) Example 1 5.66 0.63 0.36 Example 2 5.63 0.61 0.32 Example 3 5.59 0.63 0.36 Example 4 5.72 0.55 0.29 Example 5 5.65 0.59 0.33 Comparative Example 1 5.42 0.71 0.40 Comparative Example 2 5.39 0.75 0.43 Comparative Example 3 5.21 0.81 0.49 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.

[0042] 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-zirconium brick suitable for TFT glass channels, characterized in that, The high-zirconium bricks comprise the following components by mass fraction: It contains 96.3-97.7% ZrO2, 1.18-1.94% SiO2, 0.15-0.98% Al2O3, 0.04-0.08% Na2O, 0.02-0.06% K2O, 0.21-0.29% Y2O3, and 0.68-0.92% SnO2, with other components comprising less than 0.13%.

2. The high-zirconium brick suitable for TFT glass channels as described in claim 1, characterized in that, The mass ratio of Y2O3 to SnO2 is 1:3-5.

3. A method for preparing high-zirconium bricks suitable for TFT glass channels as described in claim 1, characterized in that, Includes the following steps: S1: Take desilication zircon, SiO2, Al2O3, Na2O, K2O, Y2O3 and SnO2 according to the above high zircon brick ratio; take a portion of SnO2 and pre-dope it with desilication zircon to obtain SnO2 pre-doped desilication zircon; S2: Mix the SnO2-predoped desilicationized zircon from step S1 with the remaining components to obtain a mixture; heat the mixture in an electric arc furnace to melt it to obtain 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.

4. The preparation method according to claim 3, characterized in that, In step S1, the tin oxide used for doping desiliconized zircon accounts for 60-80% of the total tin oxide.

5. The preparation method according to claim 3, characterized in that, In step S3, the casting temperature is ≥1950°C and the casting rate is 10–50 kg / s.

6. The preparation method according to claim 3, characterized in that, The specific process for tin oxide-doped desiliconized zircon in step S1 is as follows: a. Mix desilication zircon and tin oxide according to the ratio, and place the mixed raw materials together with grinding balls and anhydrous ethanol in a ball milling jar for ball milling. b. After drying, place it in a high-temperature sintering furnace, heat it to 1450-1550℃ in an air atmosphere, hold it at that temperature, and then cool it to room temperature with the furnace to obtain tin oxide-doped desiliconized zirconium.

7. The preparation method according to claim 6, characterized in that, In step a, the ball-to-material ratio in the ball milling process is (5-10):

1.

8. The preparation method according to claim 6, characterized in that, In step a, the ball milling time is 12-48 hours, and the ball milling is carried out until the D50 particle size of the mixed powder is less than 0.8μm.

9. The preparation method according to claim 6, characterized in that, The heating rate in step b is 3-5℃ / minute.

10. The preparation method according to claim 6, characterized in that, The heat preservation time in step b is 2-6 hours.

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