ZTA composite ceramic grading wheel and preparation method thereof

Abstract

The invention belongs to the technical field of ceramic products, and particularly relates to a ZTA composite ceramic grading wheel and a preparation method thereof. The preparation method of the ZTA composite ceramic grading wheel comprises the following steps: firstly, mixing and grinding aluminum oxide, zirconium oxide, a sintering aid, a dispersing agent and a lubricating agent, and carrying out spray granulation; then sequentially carrying out dry pressing molding, cold isostatic pressing molding and hot pressing molding, and treating to obtain a near-net-size green body; and finally, the ZTA composite ceramic grading wheel is obtained through sintering and surface treatment. The dry pressing pressure is 50-200MPa, and pressing to obtain a green body with the density of 50-60%; and the cold isostatic pressing molding is to pressurize the sheath to 100-300MPa. The hot press molding is pressing at the temperature of 1300-1500 DEG C and the pressure of 20-50 MPa. The ZTA composite ceramic grading wheel provided by the invention is high in fracture toughness, high in hardness and high in dynamic balance precision, and the invention further provides a preparation method of the ZTA composite ceramic grading wheel.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic products, and particularly relates to a ZTA composite ceramic classifying wheel and a preparation method thereof. Background Art

[0002] As a core component of airflow classifying equipment, the performance of ceramic classifying wheels directly impacts the particle size distribution accuracy and production efficiency of powder materials. While traditional alumina ceramic classifying wheels offer advantages such as high hardness and wear resistance, they suffer from low fracture toughness. They are prone to brittle fracture under high-speed rotation (linear speed ≥50 m / s) and impact loads, leading to equipment downtime. Zirconia-toughened alumina (ZTA) ceramics significantly improve material toughness by incorporating a ZrO2 phase transformation toughening mechanism.

[0003] However, grading wheels typically feature an integrated hub and radial blades. Traditional dry pressing methods are prone to density unevenness, delamination, and microcracks, resulting in post-sintering deformations as high as 0.5-1.0%, making them difficult to meet precision grading requirements (diameter tolerances must be ≤±0.1mm). Furthermore, ZrO2 phase transformation toughening requires precise control of tetragonal phase stability, but high-temperature sintering can easily induce abnormal ZrO2 grain growth, reducing the toughening effect. While low-temperature sintering can inhibit grain growth, it lacks density, leading to reduced hardness and wear resistance. The high hardness of the sintered body makes diamond machining inefficient and costly, while electrospark machining (EDM) can easily introduce surface microcracks. High-speed dynamic balancing accuracy is difficult to maintain, and traditional counterweight correction can damage the ceramic's structural integrity. Inhomogeneous raw material mixing or poor granulation powder flowability can lead to Al2O3 / ZrO2 agglomeration in the microstructure, resulting in large localized toughness fluctuations. Improper cooling rates can induce uncontrolled ZrO2 phase transformations, creating microcrack networks and reducing thermal shock resistance.

[0004] Although current improved processes (such as cold isostatic pressing or hot pressing sintering) can partially improve density, they cannot take into account the molding accuracy of complex structures, the controllability of ZrO2 phase transformation and the cost of large-scale production.

[0005] CN119430969A discloses a warm-sintering method for preparing zirconia-toughened alumina (ZTA) ceramics and their products. The method involves mixing alumina powder, yttrium-stabilized zirconia powder, and ZTA ceramic sintering aids (boric acid, sodium carbonate, potassium carbonate, calcium fluoride, bismuth trioxide, ammonium dihydrogen phosphate, antimony trioxide, and silicon dioxide), adding a binder, and dry-pressing the mixture. The mixture is then placed in a mold and sintered at 1200-1300°C to produce the ZTA ceramic product. This method employs traditional dry-pressing, which is highly susceptible to density unevenness, delamination, and microcracks in grading wheels with complex geometries (such as an integrated hub and radial blade structure). Furthermore, direct sintering after pressing can lead to severe edge and ceramic chipping during green body processing, resulting in a high scrap rate.

[0006] CN116352057A discloses a ZTA ceramic particle composite wear-resistant part and a preparation method thereof. Alumina micropowder, zirconium oxide micropowder, flux (yttrium oxide, titanium oxide, calcium oxide, magnesium oxide), dispersant (ammonium polymethacrylate, ammonium polyacrylate, ammonium citrate, polyacrylic acid), and forming agent (polyvinyl alcohol, carboxymethyl cellulose) are first ball-milled with water and pressed into a granular body. The body is then mixed with a binder and added to a powder capable of undergoing an exothermic reaction to form a granular body with a coating layer. The granular body with the coating layer is then fabricated into a prefabricated block with a preset porosity. The prefabricated block is then placed in a wear-resistant part mold, and high-temperature molten metal is poured into the prefabricated block. After solidification, the ZTA ceramic particle-metal composite wear-resistant part is obtained. The ZTA ceramic particles are coated with a metal matrix. This method of casting the prefabricated block with molten metal does not allow for precise control of the complex geometric shape and strict dimensional tolerances of the grading wheel. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a ZTA composite ceramic grading wheel with strong fracture toughness, high hardness and high dynamic balancing accuracy. The present invention also provides a preparation method thereof.

[0008] The preparation method of the ZTA composite ceramic classifying wheel of the present invention comprises the following steps: firstly, alumina, zirconia, a sintering aid, a dispersant, and a lubricant are mixed and ground, and then spray granulated; then, dry pressing, cold isostatic pressing, and hot pressing are sequentially performed to obtain a near-net-size green body; finally, sintering and surface treatment are performed to obtain the ZTA composite ceramic classifying wheel; The dry pressing pressure is 50-200 MPa, and the green body is pressed into a density of 50-60%; Cold isostatic pressing is to pressurize the package to 100-300MPa to improve the overall density uniformity, and the holding time is 5-30s.

[0009] Hot pressing is carried out at a temperature of 1300-1500°C and a pressure of 20-50MPa, which promotes particle rearrangement and plastic deformation and is suitable for high density requirements (relative density ≥95%).

[0010] The prepared ZTA granulated powder is pressed and processed into green compacts. The classifying wheel has a complex structure (typically an integrated hub and radial blades), requiring a high-density, low-defect green compact to avoid sintering deformation. Classifying wheels typically range in diameter from 50 to 500 mm. The pressed green compacts undergo lathing, milling, and other processes, followed by fine finishing to ensure defect-free and dimensional stability, laying the foundation for a high-performance classifying wheel after sintering.

[0011] The raw materials are prepared according to the following mass percentages: 60-80% alumina, 15-35% zirconium oxide, 0.5-2% sintering aid, 0.3-1.5% dispersant, and 0.3-1.5% lubricant.

[0012] The grinding process is first ball milling with the raw material, balls, and water in a ratio of 1:2-3:1-2 for 5-8 hours, followed by sand milling to a fineness D50 < 0.9 μm, and finally stirring milling. 0.3-0.5% of the total weight of the raw material binder is added to the stirred mill. The binder is polyvinyl chloride (PVA).

[0013] The spray granulation equipment is a centrifugal drying tower, the nozzle frequency is controlled at 20-22Hz, the control temperature of the spray granulation is 250-270℃ inlet temperature, 85-95℃ outlet temperature, and the granulation particle size is 20μm-150μm.

[0014] The sintering atmosphere is nitrogen or argon to prevent Al2O3 from being reduced.

[0015] The sintering temperature and curve are: Heating stage: heating at 5-10℃ / min, from room temperature to 600℃, to remove the adsorbed water and organic additives from the green body and avoid cracking of the green body; Holding stage: 600℃ → sintering temperature, sintering temperature is 1000-1300℃, holding for 1-3h, using sintering aids to promote solid phase diffusion and liquid phase generation; High temperature sintering stage: sintering temperature → target temperature, the target temperature is 1450-1550℃, keep warm for 4-5h, make the relative density ≥99%; Cooling stage: Cooling to room temperature at a rate of 5-10°C / min prevents thermal stress-induced ZrO phase transformation (tetragonal to monoclinic) that can lead to microcracks. Sintering is the core step in developing the properties of ZTA ceramics, requiring control of temperature, atmosphere, and time to achieve sufficient densification of the Al₂O₃ and ZrO₂ phases and phase toughening. After sintering, some ZrO₂ (tetragonal phase, t-ZrO₂) remains stable at room temperature. When microcracks are generated by external forces, the stress at the crack tip induces the transformation of t-ZrO₂ to the monoclinic phase (m-ZrO₂), resulting in a volume expansion of approximately 4%, counteracting crack propagation and achieving toughening.

[0016] The surface treatment is one or more of rough machining, fine machining and special machining.

[0017] Rough machining: Use a diamond grinding wheel to turn or mill to remove the blank allowance and control the dimensional tolerance (such as diameter ±0.1mm); Finishing: Grinding with a cubic boron nitride (CBN) grinding wheel to ensure surface roughness (Ra ≤ 0.8 μm) and avoid increased wear caused by embedding of powder particles; Special machining: If high-precision holes or slots are required (such as mounting shaft holes), electrical discharge machining (EDM) or laser cutting can be used.

[0018] Dynamic balancing: The grading wheel must rotate at high speed (typically 50-150 m / s), and the dynamic balancing accuracy must meet G2.5 (ISO 1940 standard). Imbalance is detected using a dynamic balancing machine, and corrections are performed by drilling or welding counterweights at the corresponding locations.

[0019] Surface strengthening (optional): For high wear scenarios (such as graded carbide powder), surface coating (such as WC-Co, CrN) or ion implantation (such as N + 、C + ), improve surface hardness and corrosion resistance.

[0020] Alumina is α-Al2O3 micropowder with a purity of ≥99.9% and a particle size of 1-1.5μm. It is the matrix phase. If it is too fine, it will easily agglomerate, and if it is too coarse, it will affect sintering densification.

[0021] The zirconia is yttrium-stabilized zirconia with a Y2O3 content of 5%-6%, which is a toughening phase to inhibit the phase transformation of ZrO2 to monoclinic phase at room temperature (the key to phase transformation toughening).

[0022] Sintering aids are one or more of CaO, MgO, SiO2, and Suzhou clay. They lower the sintering temperature (promote liquid-phase sintering) and reduce grain boundary impurities. CaO promotes liquid-phase sintering or inhibits grain growth.

[0023] The dispersant is ammonium polyacrylate, which improves the uniformity of raw material mixing.

[0024] The lubricant is stearic acid, which reduces friction resistance during molding.

[0025] A ZTA composite ceramic classifying wheel is prepared by the preparation method.

[0026] Specifically, the preparation method of the ZTA composite ceramic classifying wheel comprises the following steps: (1) 60-80% alumina, 15-35% zirconia, 0.5-2% sintering aids (CaO, MgO, SiO2, Suzhou soil), 0.3-1.5% ammonium polyacrylate, and 0.3-1.5% stearic acid were mixed, and ball milled for 5-8 hours according to the mass ratio of raw materials, balls, and water of 1:2-3:1-2, and then sand milled to a fineness of D50 < 0.9 μm. Finally, stirred milling was performed, and 0.3-0.5% PVA of the total mass of the raw materials was added to the stirred mill.

[0027] (2) Spray granulation: A centrifugal drying tower is used, and the nozzle frequency is controlled at 20-22 Hz. The control temperature of the spray granulation is an inlet temperature of 250-270 ° C, an outlet temperature of 85-95 ° C, and the granulation particle size is 20 μm-150 μm to obtain ZTA granulated powder.

[0028] (3) According to the integrated design of hub + radial blade, the grading wheel has a diameter of 50-500mm. The ZTA granulated powder is pressed into a green body with a density of 50-60% by dry pressing at 50-200MPa; the green body is cold isostatically pressed at a pressure of 100-300MPa, and the holding time is 5-30s; the green body is pressed at a temperature of 1300-1500℃ and a pressure of 20-50MPa. The pressed green body is turned, engraved and milled, and then finely trimmed to obtain a green body with a near-net size.

[0029] (4) Sintering is carried out in a nitrogen or argon atmosphere according to the following sintering temperature curve: Heating stage: heating at 5-10℃ / min, room temperature → 600℃; Holding stage: 600℃→sintering temperature, sintering temperature is 1000-1300℃, holding for 1-3h; High temperature sintering stage: sintering temperature → target temperature, the target temperature is 1450-1550℃, keep warm for 4-5h, make the relative density ≥99%; Cooling stage: cool to room temperature at 5-10℃ / min; (5) Use diamond grinding wheel for rough turning or milling to remove the blank allowance and control the dimensional tolerance. Use cubic boron nitride (CBN) grinding wheel for fine grinding to ensure the surface roughness (Ra≤0.8μm). The grading wheel rotates at high speed (linear speed 50-150m / s). The dynamic balance accuracy must reach G2.5 level (ISO 1940 standard) to obtain ZTA composite ceramic grading wheel.

[0030] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method of the ZTA composite ceramic grading wheel of the present invention adopts cold isostatic pressing to eliminate density gradient and hot pressing to promote particle rearrangement, thereby obtaining a highly dense green body, reducing sintering shrinkage stress, and avoiding deformation and cracking; sintering and slow cooling inhibit ZrO2 phase transformation microcracks, tetragonal zirconia stress-induced phase transformation toughening, and synergistically improving toughness.

[0031] (2) The preparation method of the ZTA composite ceramic grading wheel of the present invention adopts a three-stage forming process to ensure the uniformity of the green body, and the green body is close to the net size after sintering, with a small finishing allowance, and the dynamic balance correction drilling / counterweight requirement is reduced, achieving G2.5 level accuracy.

[0032] (3) The preparation method of the ZTA composite ceramic classifying wheel of the present invention optimizes the powder fluidity by spray granulation parameters, and the sintering aid reduces the densification temperature and energy consumption, which is in line with the trend of green manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the ZTA composite ceramic classifying wheel of the present invention.

[0034] Figure 2 Schematic diagram of the internal structure of the ZTA composite ceramic classifying wheel of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to specific embodiments.

[0036] The aluminum oxide used in the following examples and comparative examples is α-Al2O3 fine powder with a purity of ≥99.9% and a particle size of 1-1.5 μm. The zirconium oxide is yttrium-stabilized zirconium oxide with a Y2O3 content of 5%-6%.

[0037] Example 1 The preparation method of the ZTA composite ceramic classifying wheel comprises the following steps: (1) 70% alumina, 25% zirconia, 1.5% sintering aid CaO, 0.5% sintering aid Suzhou soil, 1.5% ammonium polyacrylate, and 1.5% stearic acid were mixed and ball milled for 6 h in a mass ratio of raw materials, balls, and water of 1:2:1. The mixture was then sand milled to a fineness of D50 < 0.9 μm and stirred milled. 0.4% PVA based on the total mass of the raw materials was added to the stirred mill.

[0038] (2) Spray granulation: A centrifugal drying tower is used, and the nozzle frequency is controlled at 21 Hz. The control temperature of the spray granulation is 260 ° C inlet temperature and 90 ° C outlet temperature. The granulation particle size is 20 μm-150 μm, and ZTA granulation powder is obtained.

[0039] (3) According to the integrated design of hub + radial blade, the grading wheel has a diameter of 100 mm. The ZTA granulated powder is pressed into a green body with a density of 55% by dry pressing at 150 MPa; the green body is cold isostatically pressed at a pressure of 200 MPa with a holding time of 10 s; the green body is pressed at a temperature of 1400 ° C and a pressure of 30 MPa. The pressed green body is turned, engraved and milled, and then finely trimmed to obtain a green body with a near-net size.

[0040] (4) Sintering is carried out under nitrogen atmosphere according to the following sintering temperature curve: Heating stage: heating at 7°C / min, room temperature → 600°C; Holding stage: 600℃→1100℃, holding for 2h; High temperature sintering stage: 1100℃→1500℃, keep warm for 5h, make relative density ≥99%; Cooling stage: cool down to room temperature at 7°C / min.

[0041] (5) Use diamond grinding wheel for rough turning to remove blank allowance and control dimensional tolerance, and use cubic boron nitride (CBN) grinding wheel for fine grinding to ensure surface roughness (Ra≤0.8μm) to obtain ZTA composite ceramic grading wheel. Figure 1-2 shown.

[0042] Example 2 The preparation method of the ZTA composite ceramic classifying wheel comprises the following steps: (1) 60% alumina, 35% zirconia, 1.5% sintering aid MgO, 0.5% sintering aid Suzhou soil, 1.5% ammonium polyacrylate, and 1.5% stearic acid were mixed and ball milled for 8 h in a mass ratio of raw materials, balls, and water of 1:3:2. The mixture was then sand milled to a fineness of D50 < 0.9 μm and stirred milled. 0.5% PVA based on the total mass of the raw materials was added to the stirred mill.

[0043] (2) Spray granulation: A centrifugal drying tower is used, and the nozzle frequency is controlled at 20 Hz. The control temperature of the spray granulation is 250 ° C inlet temperature and 85 ° C outlet temperature. The granulation particle size is 20 μm-150 μm, and ZTA granulation powder is obtained.

[0044] (3) According to the integrated design of hub + radial blade, the grading wheel has a diameter of 50 mm. The ZTA granulated powder is pressed into a green body with a density of 60% by dry pressing at 200 MPa; the green body is cold isostatically pressed at a pressure of 300 MPa with a holding time of 30 s; the green body is pressed at a temperature of 1500 ° C and a pressure of 50 MPa. The pressed green body is turned, engraved and milled, and then finely trimmed to obtain a green body with a near-net size.

[0045] (4) Sintering is carried out under nitrogen atmosphere according to the following sintering temperature curve: Heating stage: heating at 10℃ / min, room temperature → 600℃; Holding stage: 600℃→1300℃, holding for 1h; High temperature sintering stage: 1300℃→1550℃, keep warm for 4h, make the relative density ≥99%; Cooling stage: cool down to room temperature at 10℃ / min.

[0046] (5) Rough turning is performed using a diamond grinding wheel to remove the blank allowance and control the dimensional tolerance, and fine grinding is performed using a cubic boron nitride (CBN) grinding wheel to ensure the surface roughness (Ra≤0.8μm) to obtain a ZTA composite ceramic grading wheel.

[0047] Example 3 The preparation method of the ZTA composite ceramic classifying wheel comprises the following steps: (1) 80% alumina, 18.9% zirconia, 0.5% sintering aid SiO2, 0.3% ammonium polyacrylate, and 0.3% stearic acid were mixed and ball milled for 5 h in a mass ratio of raw materials, balls, and water of 1:2:1. The mixture was then sand milled to a fineness of D50 < 0.9 μm and stirred milled. 0.3% PVA based on the total mass of the raw materials was added to the stirred mill.

[0048] (2) Spray granulation: A centrifugal drying tower is used, and the nozzle frequency is controlled at 22 Hz. The control temperature of the spray granulation is 270 ° C inlet temperature and 95 ° C outlet temperature. The granulation particle size is 20 μm-150 μm, and ZTA granulation powder is obtained.

[0049] (3) According to the integrated design of hub + radial blade, the grading wheel has a diameter of 200 mm. The ZTA granulated powder is pressed into a green body with a density of 50% by dry pressing at 50 MPa; the green body is cold isostatically pressed at a pressure of 100 MPa with a holding time of 5 s; the green body is pressed at a temperature of 1300 ° C and a pressure of 20 MPa. The pressed green body is turned, engraved and milled, and then finely trimmed to obtain a green body with a near-net size.

[0050] (4) Sintering is carried out under argon atmosphere according to the following sintering temperature curve: Heating stage: heating at 5°C / min, room temperature → 600°C; Holding stage: 600℃→1000℃, holding for 3h; High temperature sintering stage: 1100℃→1450℃, keep warm for 5h, make relative density ≥99%; Cooling stage: cool down to room temperature at 5°C / min.

[0051] (5) Use diamond grinding wheel for rough milling to remove blank allowance and control dimensional tolerance, and use cubic boron nitride (CBN) grinding wheel for fine grinding to ensure surface roughness (Ra≤0.8μm) to obtain ZTA composite ceramic grading wheel.

[0052] Example 4 The preparation method of the ZTA composite ceramic classifying wheel comprises the following steps: (1) 75% alumina, 22.6% zirconia, 1.2% sintering aid Suzhou soil, 0.6% ammonium polyacrylate, and 0.6% stearic acid were mixed and ball milled for 6 h in a mass ratio of raw materials, balls, and water of 1:2:1. The mixture was then sand milled to a fineness of D50 < 0.9 μm and stirred milled. 0.4% PVA of the total mass of the raw materials was added to the stirred mill.

[0053] (2) Spray granulation: A centrifugal drying tower is used, and the nozzle frequency is controlled at 21 Hz. The control temperature of the spray granulation is 260 ° C inlet temperature and 95 ° C outlet temperature. The granulation particle size is 20 μm-150 μm, and ZTA granulation powder is obtained.

[0054] (3) According to the integrated design of hub + radial blade, the grading wheel has a diameter of 200 mm. The ZTA granulated powder is pressed into a green body with a density of 55% by dry pressing at 70 MPa; the green body is cold isostatically pressed at a pressure of 120 MPa with a holding time of 12 s; the green body is pressed at a temperature of 1450 ° C and a pressure of 25 MPa. The pressed green body is turned, engraved and milled, and then finely trimmed to obtain a green body with a near-net size.

[0055] (4) Sintering is carried out under nitrogen atmosphere according to the following sintering temperature curve: Heating stage: heating at 6°C / min, room temperature → 600°C; Holding stage: 600℃→1100℃, holding for 2h; High temperature sintering stage: 1100℃→1500℃, keep warm for 5h, make relative density ≥99%; Cooling stage: cool down to room temperature at 6°C / min.

[0056] (5) Rough turning is performed using a diamond grinding wheel to remove the blank allowance and control the dimensional tolerance, and fine grinding is performed using a cubic boron nitride (CBN) grinding wheel to ensure the surface roughness (Ra≤0.8μm) to obtain a ZTA composite ceramic grading wheel.

[0057] Comparative Example 1 This comparative example is the same as Example 1, except that CaO in step (1) is replaced by ZnO, and the other preparations are the same.

[0058] Comparative Example 2 This comparative example is the same as Example 2, except that the step (1) is further sand-ground to a fineness of D50 < 0.9 μm and removed, and the other preparations are the same.

[0059] Comparative Example 3 This comparative example is the same as Example 3, except that the sheath in step (3) is pressurized to 100 MPa for cold isostatic pressing and removed, and the other preparations are the same.

[0060] Comparative Example 4 This comparative example is the same as Example 4, except that the cubic boron nitride (CBN) grinding wheel in step (5) is replaced by a diamond grinding wheel, and the other preparations are the same.

[0061] The ZTA composite ceramic classifying wheels prepared in the above embodiments and comparative examples were tested according to the following standards: fracture toughness GB / T23806-2009; dimensional accuracy GB / T19921-2005; dynamic balance GB / T9239.1-2006; grain size GB / T41949-2022; wear resistance GB / T18301-2012; thermal shock resistance (1000°C to room temperature) ISO10545-9:2013; density GB / T25995-2010; and corrosion resistance GB / T3810.13-2016. The test results are shown in Table 1.

[0062] Table 1 Test results

Claims

1. A method for preparing a ZTA composite ceramic classifying wheel, characterized in that: First, alumina, zirconia, sintering aid, dispersant, and lubricant are mixed and ground, and spray granulated; then dry pressing, cold isostatic pressing, and hot pressing are sequentially performed to obtain a near-net-size green body; finally, sintering and surface treatment are performed to obtain a ZTA composite ceramic classifying wheel; The dry pressing pressure is 50-200 MPa, and the green body is pressed into a density of 50-60%; Cold isostatic pressing is a process of encapsulating the steel sheet under pressure of 100-300 MPa. Hot pressing is performed at a temperature of 1300-1500°C and a pressure of 20-50 MPa.

2. The method for preparing the ZTA composite ceramic classifying wheel according to claim 1, characterized in that: The raw materials are prepared according to the following mass percentages: 60-80% alumina, 15-35% zirconium oxide, 0.5-2% sintering aid, 0.3-1.5% dispersant, and 0.3-1.5% lubricant.

3. The method for preparing the ZTA composite ceramic classifying wheel according to claim 2, characterized in that: The grinding is first ball milling, with the ratio of raw material, small balls and water being 1:2-3:1-2, ball milling for 5-8 hours, then sand milling to a fineness D50 < 0.9 μm, and finally stirring milling, in which 0.3-0.5% binder of the total weight of the raw material is added.

4. The method for preparing the ZTA composite ceramic classifying wheel according to claim 3, characterized in that: The spray granulation equipment is a centrifugal drying tower, the nozzle frequency is controlled at 20-22Hz, the control temperature of the spray granulation is 250-270℃ inlet temperature, 85-95℃ outlet temperature, and the granulation particle size is 20μm-150μm.

5. The method for preparing the ZTA composite ceramic classifying wheel according to claim 1, characterized in that: The sintering atmosphere is nitrogen or argon, and the sintering temperature and curve are: Heating stage: heating at 5-10℃ / min, room temperature → 600℃; Holding stage: 600℃→sintering temperature, sintering temperature is 1000-1300℃, holding for 1-3h; High temperature sintering stage: sintering temperature → target temperature, target temperature is 1450-1550℃, keep warm for 4-5h; Cooling stage: cool down to room temperature at 5-10℃ / min.

6. The method for preparing the ZTA composite ceramic classifying wheel according to claim 1, characterized in that: The surface treatment is one or more of rough machining, fine machining and special machining.

7. The method for preparing the ZTA composite ceramic classifying wheel according to claim 1, characterized in that: Alumina is α-Al2O3 micro powder with a purity of ≥99.9% and a particle size of 1-1.5μm.

8. The method for preparing the ZTA composite ceramic classifying wheel according to claim 7, characterized in that: The zirconium oxide is yttrium-stabilized zirconium oxide with a Y2O3 content of 5%-6%.

9. The method for preparing the ZTA composite ceramic classifying wheel according to claim 8, characterized in that: The sintering aid is one or more of CaO, MgO, SiO2 and Suzhou soil; the dispersant is ammonium polyacrylate and the lubricant is stearic acid.

10. A ZTA composite ceramic classifying wheel, characterized by: The invention is prepared by the preparation method according to any one of claims 1 to 9.

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