Zirconium-aluminum composite ceramic gate brick and preparation method thereof

Abstract

The invention relates to a zirconium-aluminum composite ceramic gate brick and a preparation method thereof, raw material powder of the zirconium-aluminum composite ceramic gate brick comprises the following chemical components in percentage by weight of oxide: 37 to 57 weight percent of Al2O3, 40 to 60 weight percent of ZrO2, 0.1 to 1.0 weight percent of MgO, 0.5 to 3.0 weight percent of SiO2 and 0.2 to 2.0 weight percent of Y2O3, wherein the raw material of the ZrO2 is 3Y-TZP powder. The zirconium-aluminum composite ceramic gate brick is high in thermal shock resistance and erosion resistance, longer in service life, higher in operation stability, capable of adapting to high-temperature harsh working conditions and capable of meeting the requirements of the modern glass industry, especially special glass manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature inorganic new materials, and in particular relates to a zirconium-aluminum composite ceramic gate brick and its preparation method. Background Technology

[0002] Gate bricks in glass furnaces are key components installed in the feed channel or flow channel of the glass melting furnace, used to precisely control the flow rate and liquid level of molten glass and isolate slag. Their working environment is extremely harsh, requiring them to withstand high temperatures of 1400-1600℃, chemical erosion by molten glass, mechanical scouring, and rapid heating and cooling. The mainstream materials are mainly divided into the following categories: 1) Sintered AZS (fused zirconia corundum brick): Its main components are Al2O3, ZrO2, and SiO2, produced by sintering. It is currently the most widely used and technologically mature material, widely used due to its excellent resistance to molten glass erosion (especially against soda-lime glass and borosilicate glass) and high high-temperature strength. Its characteristics include high hardness, good wear resistance, and moderate to high corrosion resistance. Its disadvantages include poor thermal shock resistance and susceptibility to breakage, posing a risk. 2) Fused AZS (Electrofused Zirconia Corundum Brick): Similar in composition to sintered AZS, but fused in an electric arc furnace and cast, resulting in a denser structure. It is used in critical areas requiring high resistance to erosion, such as flow channels and kiln walls. While more expensive as a gate brick, its performance is superior. Its characteristics include a dense structure, extremely low porosity, and excellent erosion resistance, making it a representative of high-end applications. Its disadvantages include poor thermal shock resistance and susceptibility to breakage, posing a risk. 3) Quartz Ceramic (Fused Quartz) Brick: Primarily composed of amorphous SiO2, it is used in the field of specialty glass where high levels of glass melt contamination are required, such as electronic glass, optical glass, and high borosilicate glass. Its advantages include an extremely low coefficient of thermal expansion, excellent thermal shock resistance, resistance to rapid heating and cooling without cracking, and poor wettability with molten glass, preventing glass contamination. Its disadvantages include crystallization (quartzization) at high temperatures, leading to decreased strength, poor erosion resistance at temperatures above 1100℃, and susceptibility to wear and perforation.

[0003] Currently, gate bricks face the following problems: 1. The contradiction between corrosion resistance and thermal shock resistance. Although AZS material has good corrosion resistance, its thermal shock resistance is poor. Due to the phase transformation characteristics of zirconia, microcracks will form inside when subjected to frequent temperature rises and falls (such as fire changes, shutdown maintenance, and material level fluctuations). Long-term accumulation leads to cracking, spalling, and eventual failure. Quartz ceramics have excellent thermal shock resistance, but insufficient high-temperature corrosion resistance, especially in highly corrosive environments such as soda-lime glass. Their service life is short, and they are prone to thinning due to corrosion, affecting adjustment accuracy or even breaking. 2. Structural spalling and contamination of molten glass. Cast AZS will exude a glassy phase at high temperatures. These glassy phases are washed into the molten glass, forming defects such as stones and streaks, affecting the quality of the finished glass product. This is an inherent characteristic and difficult to completely avoid. Moreover, all materials will experience surface spalling under long-term corrosion and thermal shock. The spalled material enters the molten glass and becomes a solid defect. 3. High-temperature strength and creep issues. Under prolonged high temperature and load (the weight of the gate brick and the pressure from above), the material will undergo high-temperature creep, leading to deformation. Once deformed, the gap between the gate and the brick groove changes, either causing it to jam or not close tightly, resulting in adjustment failure and material leakage. 4. Unstable service life and high cost.

[0004] Due to the aforementioned problems, the service life of gate bricks fluctuates greatly, ranging from a few months to one or two years. Frequent replacements not only increase spare parts costs but also lead to significant production losses due to kiln shutdowns for maintenance. While cast AZS exhibits good performance, its manufacturing cost is high. Therefore, there is an urgent need in this field for a gate brick that combines excellent thermal shock resistance and superior erosion resistance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a zirconium-aluminum composite ceramic gate brick with high thermal shock and corrosion resistance and its preparation method. The gate brick has a longer service life, higher operational stability, and can adapt to high temperature and harsh working conditions, meeting the needs of the modern glass industry, especially the manufacturing of special glass.

[0006] This invention is achieved through the following technical solution:

[0007] A zirconium-aluminum composite ceramic gate brick, the raw material powder of which is 100% by weight of oxides, has the following chemical composition: Al2O3 37-57wt%, ZrO2 40-60wt%, MgO 0.1-1.0wt%, SiO2 0.5-3.0wt%, Y2O3 0.2-2.0wt%; wherein the raw material of ZrO2 is 3Y-TZP powder.

[0008] Specifically, 3Y-TZP powder is 3 mol% Y2O3-stabilized ZrO2.

[0009] Furthermore, the D50 value of the 3Y-TZP powder is 0.3 μm.

[0010] Furthermore, the D50 value of the Al2O3 raw material powder is 0.8 μm.

[0011] Furthermore, during the high-temperature sintering process, the SiO2 forms a small amount of mullite phase with Al2O3 (3Al2O3·2SiO2).

[0012] Al₂O₃ powder serves as the main matrix phase, providing the material with high hardness, high strength, and excellent corrosion resistance. ZrO₂ powder acts as the key toughening phase, with stabilized tetragonal zirconium oxide (such as ZrO₂ stabilized with 3 mol% Y₂O₃) accounting for over 90% of the total ZrO₂ content. This toughening effect is achieved through stress-induced phase transformation, significantly improving the material's fracture toughness. MgO promotes sintering, inhibits abnormal Al₂O₃ grain growth, and increases the material's density. SiO₂ forms a small amount of mullite phase with Al₂O₃ during high-temperature sintering, which helps improve thermal shock resistance.

[0013] A method for preparing the zirconium-aluminum composite ceramic gate brick as described above includes the following steps:

[0014] S1. Wet ball mill each raw material powder according to the above weight percentages to obtain a mixed slurry;

[0015] S2. Spray dry the obtained mixed slurry to granulate it, and then sieve it to obtain granules;

[0016] S3. Fill the obtained granular material into the gate brick mold and use cold isostatic pressing to form a molded blank;

[0017] S4. The obtained molded blank is placed in a high-temperature sintering furnace and subjected to debinding, high-temperature sintering and cooling treatment in sequence to obtain gate brick blank;

[0018] S5. After machining and non-destructive testing of the obtained gate brick blank, the desired result is obtained.

[0019] Furthermore, in S1, the wet ball milling process involves placing each raw material powder in a ball mill, using zirconia balls as the grinding medium, and adding anhydrous ethanol for ball milling and mixing.

[0020] Furthermore, the mass ratio of the raw material powder, zirconium oxide balls, and anhydrous ethanol is 1:2:0.8.

[0021] Furthermore, in S2, the inlet temperature of the granulation process is 180-220°C, and the outlet temperature is 80-100°C.

[0022] Furthermore, in S3, the static pressure molding pressure is 150-250 MPa, and the time is 2-5 min.

[0023] Furthermore, dry pressing followed by cold isostatic pressing may be employed.

[0024] Furthermore, in S4,

[0025] The conditions for degreasing are: the temperature rises from room temperature to 600℃ at a rate of 2-5℃ / min;

[0026] The conditions for high-temperature sintering are: temperature rises to 1550-1600℃, and the heating rate is 4-10℃ / min;

[0027] The cooling conditions are as follows: the temperature is cooled to room temperature along with the furnace, and the cooling rate is controlled at 2-4℃ / min;

[0028] The heat preservation time for debinding is 1-2 hours, and the heat preservation time for high-temperature sintering is 2-4 hours.

[0029] The above-mentioned zirconium-aluminum composite ceramic gate brick is used in the feed channel or flow channel of a glass melting furnace.

[0030] The beneficial effects of this invention are:

[0031] 1. The gate brick of this invention possesses extremely high thermal shock resistance, erosion resistance, and scour resistance. The phase transformation toughening effect and low thermal conductivity of zirconia, combined with the optimized microstructure, enable the material to withstand the severe thermal shock caused by the start-up and shutdown of glass furnaces and fluctuations in operating conditions, without the risk of cracking. The alumina matrix itself has extremely high chemical stability and hardness, exhibiting strong resistance to the erosion and scour of high-temperature molten glass (especially alkaline molten glass), far surpassing that of quartz materials.

[0032] 2. The service life of the gate brick of the present invention is significantly extended. The improvement in overall performance allows the gate brick of the present invention to have an expected service life of more than 18 months in harsh environments above 1300°C, compared to several months for existing quartz bricks, greatly reducing the number of downtime replacements and improving production efficiency.

[0033] 3. The gate bricks of this invention exhibit high product consistency. Through optimized preparation processes (such as cold isostatic pressing and stepwise temperature-controlled sintering), the products have high density (>98% of theoretical density), uniform microstructure, and stable and reliable performance.

[0034] 4. Thermal shock resistance test results: No cracks after more than 30 water cooling cycles at 1100℃; resistance to glass melt erosion is superior to traditional AZS bricks and fused silica ceramic bricks; no glass phase precipitation occurs at high temperatures, thus avoiding contamination of the glass melt and defects such as stone formation and bubbles; expected service life is more than 18 months, which is more than 30% longer than existing products; it can achieve domestic substitution and reduce the dependence of high-end products on imported materials. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the gate brick structure;

[0036] Figure 2 This is a trend chart of the linear expansion rate test data of the zirconium-aluminum composite ceramic gate brick prepared in Example 1 of the present invention;

[0037] Figure 3 Comparison of Z60-A zirconium-aluminum composite ceramic gate brick prepared in Example 1 of the present invention and AZS-41#, ZM16, and αβ samples cut along the centerline after etching.

[0038] Figure 4 The images show a comparison of the Z60-A zirconium-aluminum composite ceramic gate brick and AZS-41#, ZM16, and αβ static corrosion resistance samples prepared in Example 1 of this invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the following embodiments,

[0041] The raw material for ZrO2 is 3Y-TZP powder with a D50 value of 0.3μm.

[0042] The D50 value of the Al2O3 raw material powder is 0.8 μm.

[0043] The preparation method of the zirconium-aluminum composite ceramic gate brick includes the following steps:

[0044] Weigh each raw material powder according to the weight percentage, use zirconia balls as the grinding medium, add anhydrous ethanol and wet ball mill for 4-12 hours. The mass ratio of raw material powder: zirconia balls: anhydrous ethanol is 1:2:0.8 to obtain a mixed slurry.

[0045] The mixed slurry is spray-dried and granulated, with the inlet temperature controlled at 180-220℃ and the outlet temperature at 80-100℃, and then passed through a 40-100 mesh sieve to obtain granules.

[0046] The obtained granules are filled into the gate brick mold and cold isostatic pressing is used for molding. The molding pressure is 150-250MPa, or dry pressing is used followed by cold isostatic pressing and holding pressure for 2-5 minutes to obtain the molded blank.

[0047] The shaped blank is placed in a high-temperature sintering furnace for sequential debinding, high-temperature sintering, and cooling.

[0048] Conditions for debinding: Increase the temperature from room temperature to 600℃ at a rate of 2-5℃ / min, and hold at that temperature for 1-2 hours.

[0049] High-temperature sintering conditions: Heat to 1550-1600℃ at a rate of 4-10℃ / min, hold for 2-4 hours.

[0050] Cooling conditions: Cool to room temperature with the furnace, with the cooling rate controlled at 2-4℃ / min.

[0051] Machining and inspection: The sintered gate brick blanks are precision ground, and the dimensional accuracy and surface finish are checked. Non-destructive testing is also performed to obtain the final product.

[0052] Example 1

[0053] A zirconium-aluminum composite ceramic gate brick, wherein the raw material powder comprises 100% oxides by weight, has the following chemical composition:

[0054] Al2O3 37wt%;

[0055] 3Y-TZP 60wt%;

[0056] MgO 0.5wt%;

[0057] SiO2 1.5wt%;

[0058] Y2O3 1.0 wt%.

[0059] The preparation method of the zirconium-aluminum composite ceramic gate brick includes the following steps:

[0060] Weigh the raw material powders according to their weight percentages. Using zirconia balls as the grinding medium, add anhydrous ethanol and perform wet ball milling for 8 hours. The mass ratio of raw material powder:zirconia balls:anhydrous ethanol is 1:2:0.8 to obtain a mixed slurry. Spray dry the mixed slurry to granulate it, controlling the inlet temperature at 200℃ and the outlet temperature at 90℃, and pass it through a 70-mesh sieve to obtain granules. Fill the obtained granules into a gate brick mold and cold isostatically press it at a molding pressure of 200MPa for 3 minutes to obtain a molded green body. Place the molded green body in a high-temperature sintering furnace, sequentially heating it from room temperature to 600℃ at a rate of 2℃ / min, holding it at that temperature for 1.5 hours to remove the binder, then heating it to 1600℃ at a rate of 4℃ / min, holding it at that temperature for 3 hours for high-temperature sintering, followed by cooling at a rate of 3℃ / min. Grind the sintered gate brick green body, check its dimensional accuracy and surface finish, and perform non-destructive testing to obtain the final product.

[0061] Example 2

[0062] A zirconium-aluminum composite ceramic gate brick, wherein the raw material powder comprises 100% oxides by weight, has the following chemical composition:

[0063] Al2O3 57wt%;

[0064] 3Y-TZP 40wt%;

[0065] MgO 0.8wt%;

[0066] SiO2 2.0wt%;

[0067] Y2O3 0.2wt%.

[0068] The preparation method of the zirconium-aluminum composite ceramic gate brick includes the following steps:

[0069] Weigh each raw material powder according to weight percentage, use zirconia balls as grinding media, add anhydrous ethanol and wet ball mill for 10 hours. The mass ratio of raw material powder:zirconia balls:anhydrous ethanol is 1:2:0.8 to obtain a mixed slurry. Spray dry the mixed slurry to granulate, control the inlet temperature to 190℃ and the outlet temperature to 90℃, and pass it through a 70-mesh sieve to obtain granules. Fill the obtained granules into a gate brick mold, dry press at 180MPa, and then cold isostatic press at 220MPa for 3 minutes to obtain a shaped green body. Place the shaped green body in a high-temperature sintering furnace and heat it sequentially from room temperature to 600℃ at 2.5℃ / min, hold for 2 hours to remove the binder, then heat it to 1600℃ at 4℃ / min, hold for 2.5 hours for high-temperature sintering, and then cool at 2.5℃ / min. The sintered gate brick blanks are ground, and the dimensional accuracy and surface finish are checked. Non-destructive testing is then performed to obtain the final product.

[0070] Example 3

[0071] A zirconium-aluminum composite ceramic gate brick, wherein the raw material powder comprises 100% oxides by weight, has the following chemical composition:

[0072] Al2O3 47wt%;

[0073] 3Y-TZP 50wt%;

[0074] MgO 0.2wt%;

[0075] SiO2 1.0wt%;

[0076] Y2O3 1.8wt%.

[0077] The preparation method of the zirconium-aluminum composite ceramic gate brick includes the following steps:

[0078] Weigh the raw material powders according to their weight percentages. Using zirconia balls as the grinding medium, add anhydrous ethanol and perform wet ball milling for 8 hours. The mass ratio of raw material powder:zirconia balls:anhydrous ethanol is 1:2:0.8 to obtain a mixed slurry. Spray dry the mixed slurry to granulate it, controlling the inlet temperature at 200℃ and the outlet temperature at 90℃, and pass it through a 70-mesh sieve to obtain granules. Fill the obtained granules into a gate brick mold and cold isostatically press it at a molding pressure of 200MPa for 3 minutes to obtain a molded green body. Place the molded green body in a high-temperature sintering furnace, sequentially heating it from room temperature to 600℃ at a rate of 2℃ / min, holding it at that temperature for 1.5 hours to remove the binder, then heating it to 1600℃ at a rate of 4℃ / min, holding it at that temperature for 3 hours for high-temperature sintering, followed by cooling at a rate of 3℃ / min. Grind the sintered gate brick green body, check its dimensional accuracy and surface finish, and perform non-destructive testing to obtain the final product.

[0079] Effect Example

[0080] 1. Linear thermal expansion coefficient test

[0081] The linear expansion rate of the zirconium-aluminum composite ceramic gate bricks obtained in Examples 1-3 was tested according to GB / T16535. The test results are shown in Table 1 below:

[0082] Table 1 Results of Linear Expansion Rate Detection

[0083]

[0084]

[0085] 2. Thermal shock resistance test

[0086] The thermal shock resistance of the zirconium-aluminum composite ceramic gate bricks obtained in Examples 1-3 and the comparative cast AZS-41# bricks was tested. The test standard was GB / T 30873-2014 (Method 1), and the test conditions were water cooling at 1100℃. The test results are shown in Table 2 below.

[0087] Table 2 Results of thermal shock resistance test

[0088] Sample Name Thermal shock resistance (secondary) Example 1 ＞30 Example 2 ＞30 Example 3 ＞30 Comparison of cast AZS-41# brick 3

[0089] As can be seen from the test results in Tables 1 and 2, the zirconium-aluminum composite ceramic gate brick of the present invention has excellent thermal shock resistance and no cracks after more than 30 water cooling cycles at 1100℃.

[0090] 3. Resistance to molten glass corrosion test

[0091] A comparative test was conducted on the Z60-A zirconium-aluminum composite ceramic gate bricks obtained in Examples 1-3, as well as Comparative Example 1 AZS-41# (fused cast zirconia corundum), Comparative Example 2 ZM16 (zirconia mullite), and Comparative Example 3 αβ (α-β alumina) against glass melt erosion. The eroding medium was ordinary soda-lime glass, the test temperature was 1300℃, and the holding time was 48h. The test results are shown in Table 3 below:

[0092] Table 3 Results of static resistance to glass melt erosion test

[0093]

[0094]

[0095] As shown in Table 3, the static resistance test data and the images of the eroded samples show that the zirconium-aluminum composite ceramic gate brick of the present invention has excellent resistance to glass melt erosion. The erosion rate at the liquid level is 0.02 mm / 24h, which is significantly lower than that of Comparative Example 1 AZS-41# (fused cast zirconia corundum), Comparative Example 2 ZM16 (zirconia mullite), and Comparative Example 3 αβ (α-β alumina). This can extend the service life of the gate brick, greatly reduce the number of downtime replacements, and improve production efficiency.

[0096] 4. Bubble Ejection Rate Detection

[0097] The bubble precipitation rate of the zirconium-aluminum composite ceramic gate bricks obtained in Examples 1-3 and the comparative cast AZS-41# bricks was tested. The test standard was JC / T 639-2013(2017), and the test conditions were 1300℃, 10h, and ordinary soda-lime glass. The test results are shown in Table 4 below.

[0098] Table 4 Results of bubble exudation rate test

[0099] Sample Name Bubble extraction rate (%) Example 1 0.6 Example 2 0.6 Example 3 0.6 Comparison of cast AZS-41# brick 1.2

[0100] The bubble precipitation rate of the above-mentioned gate bricks was tested. As shown in Table 4, the bubble precipitation rate of the zirconium-aluminum composite ceramic gate bricks in Examples 1-3 was 0.6%, and the bubble precipitation rate of the cast AZS-41# bricks was 1.2%. It can be seen that the zirconium-aluminum composite ceramic gate bricks have a good inhibitory effect on the bubble defects caused by glass furnace materials. Because its elements and density are uniform and there are no factors that change the phase structure, it always has extremely low bubble precipitation data and remains stable.

[0101] In summary, the zirconium-aluminum composite ceramic gate brick of the present invention has better thermal shock resistance and glass melt erosion resistance than traditional AZS bricks. It does not precipitate glass phase at high temperatures, does not contaminate glass melt, avoids defects such as stones and bubbles, extends service life, has high product density, uniform microstructure, and stable and reliable performance.

[0102] 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 zirconium-aluminum composite ceramic gate brick, characterized in that, The raw material powder, by weight percentage of oxides, totals 100%, and has the following chemical composition: Al2O3 37-57wt%, ZrO2 40-60wt%, MgO 0.1-1.0wt%, SiO2 0.5-3.0wt%, Y2O3 0.2-2.0wt%; wherein, the raw material of ZrO2 is 3Y-TZP powder.

2. The zirconium-aluminum composite ceramic gate brick according to claim 1, characterized in that, The D50 value of the 3Y-TZP powder is 0.3 μm.

3. The zirconium-aluminum composite ceramic gate brick according to claim 1, characterized in that, The D50 value of the Al2O3 raw material powder is 0.8 μm.

4. A method for preparing zirconium-aluminum composite ceramic gate bricks as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Wet ball mill each raw material powder according to the above weight percentages to obtain a mixed slurry; S2. Spray dry the obtained mixed slurry to granulate it, and then sieve it to obtain granules; S3. Fill the obtained granular material into the gate brick mold and use cold isostatic pressing to form a molded blank; S4. The obtained molded blank is placed in a high-temperature sintering furnace and subjected to debinding, high-temperature sintering and cooling treatment in sequence to obtain gate brick blank; S5. After machining and non-destructive testing of the obtained gate brick blank, the desired result is obtained.

5. The method for preparing zirconium-aluminum composite ceramic gate brick according to claim 4, characterized in that, In S1, the wet ball milling process involves placing the raw material powders in a ball mill, using zirconia balls as the grinding medium, and adding anhydrous ethanol for ball milling and mixing.

6. The method for preparing zirconium-aluminum composite ceramic gate brick according to claim 5, characterized in that, The raw material powder: The mass ratio of zirconia spheres to anhydrous ethanol is 1:2:0.

8.

7. The method for preparing zirconium-aluminum composite ceramic gate brick according to claim 4, characterized in that, In S2, the inlet temperature of the granulation is 180-220℃, and the outlet temperature is 80-100℃.

8. The method for preparing zirconium-aluminum composite ceramic gate brick according to claim 4, characterized in that, In S3, the static pressure molding pressure is 150-250 MPa, and the time is 2-5 min.

9. The method for preparing zirconium-aluminum composite ceramic gate brick according to claim 4, characterized in that, In S4, The conditions for degreasing are: the temperature rises from room temperature to 600℃ at a rate of 2-5℃ / min; The conditions for high-temperature sintering are: temperature rises to 1550-1600℃, and the heating rate is 4-10℃ / min; The cooling conditions are as follows: the temperature is cooled to room temperature along with the furnace, and the cooling rate is controlled at 2-4℃ / min; The heat preservation time for debinding is 1-2 hours, and the heat preservation time for high-temperature sintering is 2-4 hours.

10. The application of the zirconium-aluminum composite ceramic gate brick according to any one of claims 1-3 in the material channel or flow channel of a glass melting furnace.

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