A method for preparing yttria powder and a method for preparing ceramic material based on the same

Abstract

The application discloses a preparation method of yttrium oxide powder and a preparation method of ceramic materials based on the same. The preparation of the yttrium oxide powder comprises the following steps: mixing deionized water and glycerol to obtain a mixed solvent, adding soluble yttrium salt, a dispersing agent and a mineralizer, adjusting the pH value to 7-12 to form a precursor mixture; transferring the precursor mixture into a high-pressure reaction kettle with a polytetrafluoroethylene lining, keeping the temperature at 180-200 DEG C for 24-48 hours, centrifuging and washing the precipitate after cooling, and pre-sintering at 700-1000 DEG C to obtain the yttrium oxide powder. The preparation of the ceramic material comprises the following steps: preparing the powder into a slurry with a solid content of 40%-60%, adding a dispersing agent and a binder to spray granulation, forming by die pressing and cold isostatic pressing, and sintering at 1300-1600 DEG C to obtain the ceramic material. The hydrothermal method is combined with the mixed pressing forming process, the prepared yttrium oxide powder has high purity, uniform particle size and good dispersity, the ceramic material has a density greater than 99% and excellent light transmission, the process is simple, the energy consumption is low, and the application is suitable for the fields of transparent ceramics, laser media and the like.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic material preparation technology, specifically to a method for preparing yttrium oxide powder, and also to a method for preparing ceramic materials using the yttrium oxide powder as raw material. Background Technology

[0002] Yttrium oxide, as an important rare earth oxide, possesses excellent high-temperature resistance, chemical stability, optical transparency, and unique electrical and catalytic properties, making it irreplaceable in high-end fields such as transparent ceramics, laser media, electronic ceramics, and catalytic materials. With the continuous development of materials science, when the size of yttrium oxide enters the nanoscale range of 1-100 nanometers, it exhibits even more prominent performance advantages due to surface effects, small size effects, and quantum effects. Its specific surface area increases significantly, its chemical activity is greatly enhanced, and its sintering temperature is significantly reduced. As a ceramic raw material, it can achieve densification at temperatures far lower than micron-sized powders, and the reduced light scattering at the nanoscale results in superior light transmittance. These unique properties greatly expand the application scenarios of yttrium oxide materials and promote the rapid development of yttrium oxide nanopowder preparation technology.

[0003] Currently, high-energy ball milling is one of the most widely used traditional techniques for preparing yttrium oxide powder. This method is a top-down physical preparation process that uses mechanical force to break large yttrium oxide materials into fine particles. It holds a significant position in industrial production due to its advantages such as simple equipment, convenient operation, low cost, large processing capacity, and suitability for large-scale production. A typical process usually includes: adding powdered yttrium oxide, a dispersant, and a mineralizer to deionized water in a specific ratio and stirring to form a slurry; then transferring the slurry to a PTFE-lined stainless steel ball mill jar and ball milling at 200-300 rpm for 2-3 hours; after confirming the slurry particle size meets the requirements using a Malvern test; finally, transferring the slurry to a granulation tower for spray granulation; and finally sintering in a Malvern furnace at 1300-1500℃ for 2-4 hours to obtain the yttrium oxide product.

[0004] However, in high-end applications where the purity, morphological precision, and nanoscale size requirements of yttrium oxide powder are becoming increasingly stringent, the inherent defects of traditional ball milling methods are becoming more and more prominent, becoming a key bottleneck restricting its application expansion.

[0005] The introduction of impurities is a significant problem: During ball milling, the grinding media (such as zirconia balls, alumina balls, agate balls, etc.) and the inner wall of the milling jar undergo wear due to high-speed impact and friction. Wear products are directly mixed into the powder, and even with the hardest zirconia balls, zirconium impurities are introduced. Simultaneously, wear on the milling jar material (such as stainless steel, hardened steel, polyurethane, etc.) also introduces additional impurities. For products requiring extremely high purity, such as optical ceramics and electronic ceramics, trace impurities can create structural defects, severely scatter light, or damage electrical properties, leading to a sharp decline in product performance.

[0006] Powders are susceptible to contamination: The ball milling process is usually carried out in the air, where moisture and oxygen can easily react with the newly formed active surfaces of the powder, causing atmospheric contamination. If wet ball milling is used, grinding media (such as alcohol and hexane) may remain or decompose, and the addition and subsequent removal of ball milling aids (such as dispersants and binders) are complicated, further increasing the risk of powder contamination.

[0007] Poor controllability of powder morphology and structure: Ball milling is essentially a violent crushing process, resulting in powder particles with sharp edges and irregular shapes, poor flowability, and the need for additional classification, which increases the complexity of the process. At the same time, the mechanical stress generated by high-energy ball milling can cause a large number of dislocations, lattice distortions, and even amorphization inside yttrium oxide particles, destroying the integrity of the crystal structure.

[0008] It is difficult to obtain high-quality nanoscale powders: When the particle size is reduced to a certain extent, van der Waals forces and other effects will cause the particles to agglomerate, making further crushing extremely difficult. It is difficult to prepare nanoscale powders with a particle size of less than 100nm and uniform dispersion by simply relying on ordinary ball milling, which cannot meet the requirements of high-end fields for powder size and dispersibility.

[0009] High energy consumption and low efficiency: To achieve fine or ultrafine grinding, the ball milling process usually takes tens or even hundreds of hours, resulting in high energy consumption. Moreover, most of the energy is consumed in the collision, friction and heat generation between the grinding balls and the grinding jar, and the effective energy utilization rate for powder crushing is extremely low, which does not conform to the industrial development trend of energy conservation and consumption reduction. Summary of the Invention

[0010] The purpose of this invention is to provide a method for preparing yttrium oxide powder, so as to solve the technical problems existing in the background art.

[0011] The present invention provides a method for preparing yttrium oxide powder, comprising the following steps:

[0012] S1, Solvent preparation: Deionized water and glycerol are mixed at a mass ratio of 85%-95%:5%-15% to obtain a mixed solvent;

[0013] S2, Precursor preparation: Add soluble yttrium salt, dispersant and mineralizer to the mixed solvent, stir to form precursor reaction mixture, adjust the pH of the mixture to 7-12, and continue stirring for 3-5 min;

[0014] S3, Reactor filling: The precursor reaction mixture is transferred to a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and the filling degree is 70%-80% of the liner volume. After sealing, it is placed in an oven and heated to 180℃-200℃ for 24h-48h.

[0015] S4, Cooling and centrifugal washing: After the reaction is complete, the reaction vessel is naturally cooled to room temperature. The precipitate is removed and repeatedly centrifuged and washed with deionized water and ethanol to remove impurities and unreacted substances.

[0016] S5, Powder pre-sintering: The washed precipitate is dried and placed in a Marfie furnace and calcined at 700℃-1000℃ for 3-6 hours to obtain yttrium oxide powder.

[0017] In a preferred embodiment, in S2, the soluble yttrium salt is at least one of yttrium nitrate, yttrium chloride, yttrium acetate, yttrium sulfate, or yttrium perchlorate.

[0018] In a preferred embodiment, in S2, the dispersant is one or a combination of polyethylene glycol (PEG) and CE-64, wherein the molecular weight of the polyethylene glycol is 1000-2000.

[0019] In a preferred embodiment, in S2, the mineralizing agent is ammonia or ammonium bicarbonate, and the pH of the precursor reaction mixture is adjusted to 9-10.

[0020] In a preferred embodiment, in step S3, the reaction temperature is 180℃-200℃, the holding time is 24h-48h, and the filling degree of the reaction vessel is 75%-80%.

[0021] In a preferred embodiment, in S5, the pre-sintering temperature is 850℃-950℃ and the calcination time is 4h.

[0022] A method for preparing a ceramic material, comprising the following steps, using yttrium oxide powder prepared by the above method:

[0023] A1, Slurry preparation: Mix the yttrium oxide powder with deionized water to prepare a yttrium oxide slurry with a solid content of 40%-60%. Add dispersant and binder to the slurry and stir with an electric mixer for 0.5-1h until uniformly dispersed.

[0024] A2, Spray granulation: The uniformly dispersed slurry is sprayed and granulated through a granulation tower. The peristaltic pump feed rate is 23-28 ml / min, the atomizing disc operating frequency is 35-55 Hz, and the granulated powder is naturally cooled to room temperature after spraying to obtain yttrium oxide granulated powder.

[0025] A3, Mixed pressing molding: The yttrium oxide granulated powder is placed in a mold for green body molding, with a molding pressure of 0.1-0.3 MPa. Then it is sealed and packaged and placed in a cold isostatic press with a pressing pressure of 195-205 MPa to obtain a ceramic green body.

[0026] A4, Sintering: The ceramic blank is calcined at 1300℃-1600℃ for 2.5-4.5h at a heating rate of 1-4℃ / min, and then cooled in the furnace to obtain yttrium oxide ceramic material.

[0027] In a preferred embodiment, in A1, the amount of dispersant added is 0.5% of the mass of yttrium oxide powder, the binder is polyvinyl alcohol, and the amount added is 0.1% of the mass of yttrium oxide powder; the solid content of the slurry is 40%-50%.

[0028] In a preferred embodiment, in A3, the molding pressure of the raw preform is 0.2 MPa, and the cold isostatic pressing pressure is 200 MPa;

[0029] In a preferred embodiment, in A4, the heating rate is 2-3℃ / min, the sintering temperature is 1400℃-1500℃, and the calcination time is 3h.

[0030] The beneficial effects of the technical solution of this invention are:

[0031] This invention prepares yttrium oxide powder via a hydrothermal method, and combines it with a specific mixing, pressing, molding, and sintering process. This solves the problems of impurity introduction, coarse particle size, uneven distribution, low ceramic density, and poor light transmittance that exist in traditional ball milling methods. The prepared yttrium oxide powder and ceramic materials have excellent comprehensive properties and are more suitable for high-end fields such as transparent ceramics and laser media. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the preparation process of yttrium oxide powder and ceramics according to the present invention.

[0033] Figure 2 This is a scanning electron microscope image of a comparative example of the present invention.

[0034] Figure 3 This is a scanning electron microscope image of Embodiment 1 of the present invention. Detailed Implementation

[0035] The present invention will now be described in further detail. The embodiments of the invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0036] The preparation process of yttrium oxide powder and ceramics according to the technical solution of this invention is as follows: Figure 1 As shown.

[0037] Example 1

[0038] I. Preparation of Yttrium Oxide Powder

[0039] S1, Solvent preparation: Deionized water and glycerol are mixed at a mass ratio of 95%:5% and stirred evenly to obtain a mixed solvent. Glycerol can dissolve potential hard agglomerates and organic impurities in the powder and enhance the efficiency of subsequent hydrothermal reactions.

[0040] S2, Precursor preparation: Weigh a self-made yttrium nitrate solution with a concentration of 0.5 mol / L as a soluble yttrium salt, add polyethylene glycol (PEG-2000) as a dispersant and ammonia as a mineralizer in proportion, and stir slowly to form a precursor reaction mixture; manually add ammonia dropwise to adjust the pH of the solution to 10, stop titration, and continue stirring with a stirrer for 5 minutes to ensure that the solution composition is uniform.

[0041] S3, Reactor filling: Transfer the above precursor reaction mixture to a stainless steel high-pressure reactor lined with polytetrafluoroethylene, filling it to 75% of the liner volume; after sealing the reactor, place it in an oven at 180°C and keep it at that temperature for 24 hours to allow the yttrium salt precursor to be fully separated and hydrolyzed, thus completing the nucleation, growth, and maturation of the crystals.

[0042] S4, Cooling and Centrifugal Washing: After the reaction is complete, close the oven and allow the reactor to cool naturally to room temperature; remove the precipitate from the reactor and wash it repeatedly by centrifugation with deionized water and ethanol five times to remove impurities and unreacted raw materials.

[0043] S5, Powder pre-sintering: The washed precipitate was dried in a 60℃ oven for 12 hours, then transferred to a Marfie furnace and calcined at 850℃ for 4 hours. After natural cooling, white yttrium oxide powder was obtained.

[0044] II. Preparation of ceramic materials:

[0045] A1, Slurry preparation: Mix the above yttrium oxide powder with deionized water to prepare a yttrium oxide slurry with a solid content of 40%. Add 0.5% by weight of the yttrium oxide powder dispersant polyethylene glycol (PEG-1000) and 0.1% by weight of the binder polyvinyl alcohol to the slurry and stir with an electric mixer for 40 minutes until uniformly dispersed.

[0046] A2, Spray granulation: The uniformly dispersed slurry is sprayed and granulated through a granulation tower. The peristaltic pump feed rate is set to 25 ml / min and the atomizing disc operating frequency is 40 Hz. After spraying, the granulated powder is allowed to cool naturally to room temperature in the tower, and yttrium oxide granulated powder is collected.

[0047] A3, Mixed pressing molding: Weigh an appropriate amount of yttrium oxide granulated powder, place it in a 0.5-inch mold, and press the green body with a pressure of 0.2 MPa; after sealing and packaging the green body, place it in a cold isostatic press and press it with a pressure of 200 MPa to obtain a ceramic body.

[0048] A4, Sintering: The ceramic blank is placed in a Marfie furnace and heated to 1400℃ at a heating rate of 2℃ / min. It is then calcined at this temperature for 3 hours. After calcination, it is cooled to room temperature with the furnace to obtain yttrium oxide ceramic material.

[0049] Example 2

[0050] I. Preparation of Yttrium Oxide Powder

[0051] S1, Solvent preparation: Deionized water and glycerol are mixed at a mass ratio of 90%:10% and stirred until homogeneous to obtain a mixed solvent.

[0052] S2, Precursor preparation: Same as in Example 1, i.e., using yttrium nitrate solution, polyethylene glycol (PEG-2000) and ammonia, adjusting the pH to 10, and stirring for 5 min.

[0053] S3, Reactor filling: Same as in Example 1, filling degree 75%, heat preservation at 180℃ for 24h.

[0054] S4, Cooling and centrifugal washing: Same as in Example 1, centrifugal washing 5 times.

[0055] S5, Powder pre-sintering: Same as in Example 1, calcined at 850℃ for 4 hours to obtain yttrium oxide powder.

[0056] 2. Preparation of ceramic materials: Same as in Example 1, i.e., 40% solid content slurry, PEG-1000 dispersant, polyvinyl alcohol binder, 25 ml / min feeding rate, 40 Hz atomizing disc frequency, 0.2 MPa molding pressure, 200 MPa cold isostatic pressing pressure, 2℃ / min heating rate, and calcination at 1400℃ for 3 h.

[0057] Example 3

[0058] I. Preparation of Yttrium Oxide Powder

[0059] S1, Solvent preparation: Deionized water and glycerol are mixed at a mass ratio of 95%:5% and stirred until homogeneous to obtain a mixed solvent.

[0060] S2, Precursor preparation: Weigh a self-made yttrium chloride solution with a concentration of 0.5 mol / L as a soluble yttrium salt, add dispersant polyethylene glycol (PEG-2000) and mineralizer ammonia water, and stir to form a mixture; add ammonia water dropwise to adjust the pH value to 10, and continue stirring for 5 min.

[0061] S3, Reactor filling: Transfer the mixture to a high-pressure reactor with a filling degree of 80%; after sealing, place it in a 200℃ oven and keep it at that temperature for 24 hours.

[0062] S4, Cooling and centrifugal washing: Same as in Example 1, centrifugal washing 5 times.

[0063] S5, Powder pre-sintering: The dried precipitate is calcined at 950℃ for 4 hours to obtain yttrium oxide powder.

[0064] II. Preparation of ceramic materials:

[0065] Slurry preparation: Prepare a yttrium oxide slurry with a solid content of 40%, add 0.5% by weight of yttrium oxide powder dispersant CE-64 and 0.1% by weight of polyvinyl alcohol, and stir with an electric mixer for 60 min.

[0066] Spray granulation: Peristaltic pump feed rate 23ml / min, atomizing disc operating frequency 40Hz, granulated powder collected after cooling.

[0067] Hybrid compression molding: 0.1MPa compression molding, 205MPa cold isostatic pressing.

[0068] Sintering: The temperature is increased to 1500℃ at a heating rate of 2℃ / min, calcined for 3 hours, and then cooled in the furnace to obtain ceramic material.

[0069] Example 4

[0070] I. Preparation of Yttrium Oxide Powder

[0071] Solvent preparation: Deionized water and glycerol were mixed at a mass ratio of 95%:5% and stirred until homogeneous to obtain a mixed solvent.

[0072] Precursor preparation: Weigh a self-made yttrium nitrate solution with a concentration of 0.5 mol / L, add dispersant CE-64 and mineralizer ammonium bicarbonate, and stir to form a mixture; add ammonia water dropwise to adjust the pH value to 9, and continue stirring for 3 min.

[0073] Reactor filling: The mixture is transferred to a high-pressure reactor with a filling degree of 80%; after sealing, it is placed in a 200℃ oven and kept at that temperature for 48 hours.

[0074] Cooling and centrifugal washing: Same as in Example 1, centrifugation washing 5 times.

[0075] Powder pre-sintering: The dried precipitate was calcined at 900℃ for 4 hours to obtain yttrium oxide powder.

[0076] II. Preparation of ceramic materials:

[0077] Slurry preparation: Prepare a yttrium oxide slurry with a solid content of 50%, add 0.5% polyethylene glycol (PEG-1000) and 0.1% polyvinyl alcohol by weight of yttrium oxide powder, and stir with an electric mixer for 50 min.

[0078] Spray granulation: Peristaltic pump feed rate 28ml / min, atomizing disc operating frequency 45Hz, granulated powder collected after cooling.

[0079] Hybrid compression molding: 0.3MPa compression molding, 195MPa cold isostatic pressing.

[0080] Sintering: The temperature is increased to 1500℃ at a heating rate of 3℃ / min, calcined for 3 hours, and then cooled in the furnace to obtain ceramic material.

[0081] Comparative example (traditional ball milling method)

[0082] The specific steps for preparing yttrium oxide powder and ceramic materials using the traditional ball milling method in existing technology are as follows:

[0083] Slurry preparation: Add yttrium oxide powder, polyethylene glycol (PEG-2000) dispersant, and sodium chloride mineralizer to deionized water in a certain proportion, stir evenly, and form a slurry mixture.

[0084] Slurry ball milling: The slurry mixture is transferred to a stainless steel ball mill jar lined with polytetrafluoroethylene. The ball milling speed is set to 250 rpm and the ball milling time is 2.5 h. During the process, samples are taken at regular intervals and tested with a Malvern particle size analyzer to ensure that the slurry particle size reaches the target range.

[0085] Spray granulation and post-treatment: After ball milling, the slurry was transferred to a granulation tower for spray granulation. The spraying conditions were the same as in Example 1 (feed rate of 25 ml / min, atomizing disk frequency of 40 Hz). The granulated powder was taken out and sintered in a Marfie furnace at 1400℃ for 3 h to obtain yttrium oxide powder.

[0086] Ceramic material preparation: Using the same ceramic preparation process as in Example 1 (slurry preparation, mixing and pressing molding, and sintering parameters as in "Ceramic Material Preparation" in Example 1), yttrium oxide ceramic material corresponding to the traditional ball milling method was obtained.

[0087] Performance Testing and Results Analysis

[0088] 1. The yttrium oxide powder and ceramic materials prepared in Examples 1-4 were compared with the products prepared in the comparative examples to perform performance tests. The test items included powder particle size and distribution, powder purity, ceramic density, and ceramic transmittance (wavelength 550nm). The test results are shown in the table below:

[0089] Test Project Example 1 Example 2 Example 3 Example 4 Comparative Example Average particle size of powder (nm) 65 62 58 55 180 Powder particle size distribution range (D90 / D10) 1.8 1.7 1.6 1.5 3.2 Powder purity (%) 99.95 99.96 99.97 99.98 99.52 Ceramic density (%) 99.2 99.3 99.5 99.6 95.8 Ceramic transmittance (550nm, %) 88.5 89.2 90.1 91.3 72.4

[0090] 2. The powder morphology of Example 1 and Comparative Example 1 was observed by scanning electron microscopy (SEM).

[0091] like Figure 2 As shown, the yttrium oxide powder prepared by ball milling in the comparative example has sharp edges and irregular shape, and obvious agglomeration. This corresponds to the data in the table that its particle size is large (180nm) and its distribution range is wide (3.2), which is an inevitable result of the violent crushing characteristics of ball milling. Figure 3 The results show that the powder particles prepared by the method of the present invention are regular spherical, uniformly dispersed, and without obvious agglomeration. This is consistent with the data in the table of particle size of 55-65nm and distribution span of less than 2.0, demonstrating the effect of the present invention on the control of powder morphology and particle size.

[0092] From the above performance test structure, we can see that:

[0093] Regarding particle size: the average particle size of the yttrium oxide powder prepared in Examples 1-4 is between 55-65 nm, which is much smaller than the 180 nm of the comparative example, and the particle size distribution span (D90 / D10) is less than 2.0. This indicates that the powder prepared by the method of the present invention has a finer particle size and a more uniform distribution, which solves the problem that the traditional ball milling method is difficult to obtain nanoscale powder and has a wide particle size distribution.

[0094] Regarding purity: The powder purity of Examples 1-4 all reached over 99.95%, which is significantly higher than the 99.52% of the comparative example. This is because the present invention uses a closed high-pressure reactor for hydrothermal reaction, which avoids the introduction of impurities caused by wear of grinding media and atmosphere pollution in ball milling, thus greatly improving the purity of powder.

[0095] Regarding the performance of ceramic materials: Firstly, the density of the ceramic materials prepared in the first embodiment is all above 99.2%, reaching a maximum of 99.6%, while the comparative example is only 95.8%. This is due to the fact that the powder prepared by this invention has good dispersibility and complete crystallinity, and the mixing and pressing molding process effectively eliminates the density gradient, resulting in uniform shrinkage and higher densification of the green body during sintering.

[0096] Secondly, the transmittance of the ceramic materials in the examples all exceeded 88% at a wavelength of 550nm, reaching a maximum of 91.3%, which is much higher than the 72.4% of the comparative example. This is because the powder has high purity, uniform particle size, and few agglomerates, which reduces impurities, defects, and light scattering centers inside the ceramic, thereby significantly improving the light transmittance.

[0097] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art or related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A method for preparing yttrium oxide powder, characterized in that, Includes the following steps: S1, Solvent preparation: Deionized water and glycerol are mixed at a mass ratio of 85%-95%:5%-15% to obtain a mixed solvent; S2, Precursor preparation: Add soluble yttrium salt, dispersant and mineralizer to the mixed solvent, stir to form precursor reaction mixture, adjust the pH of the mixture to 7-12, and continue stirring for 3-5 min; S3, Reactor filling: The precursor reaction mixture is transferred to a stainless steel high-pressure reactor with a polytetrafluoroethylene liner, and the filling degree is 70%-80% of the liner volume. After sealing, it is placed in an oven and heated to 180℃-200℃ for 24h-48h. S4, Cooling and centrifugal washing: After the reaction is complete, the reaction vessel is naturally cooled to room temperature. The precipitate is removed and repeatedly centrifuged and washed with deionized water and ethanol to remove impurities and unreacted substances. S5, Powder pre-sintering: The washed precipitate is dried and placed in a Marfie furnace and calcined at 700℃-1000℃ for 3-6 hours to obtain yttrium oxide powder.

2. The method for preparing yttrium oxide powder according to claim 1, characterized in that, In S2, the soluble yttrium salt is at least one of yttrium nitrate, yttrium chloride, yttrium acetate, yttrium sulfate, or yttrium perchlorate.

3. The method for preparing yttrium oxide powder according to claim 1, characterized in that, In S2, the dispersant is one or a combination of polyethylene glycol (PEG) and CE-64, wherein the molecular weight of the polyethylene glycol is 1000-2000.

4. The method for preparing yttrium oxide powder according to claim 1, characterized in that, In S2, the mineralizing agent is ammonia or ammonium bicarbonate, and the pH of the precursor reaction mixture is adjusted to 9-10.

5. The method for preparing yttrium oxide powder according to claim 1, characterized in that, In step S3, the reaction temperature is 180℃-200℃, the holding time is 24h-48h, and the filling degree of the reactor is 75%-80%.

6. The method for preparing yttrium oxide powder according to claim 1, characterized in that, In S5, the pre-sintering temperature is 850℃-950℃, and the calcination time is 4h.

7. A method for preparing a ceramic material, characterized in that, The yttrium oxide powder prepared by the preparation method according to any one of claims 1-6 includes the following steps: A1, Slurry preparation: Mix the yttrium oxide powder with deionized water to prepare a yttrium oxide slurry with a solid content of 40%-60%. Add dispersant and binder to the slurry and stir with an electric mixer for 0.5-1h until uniformly dispersed. A2, Spray granulation: The uniformly dispersed slurry is sprayed and granulated through a granulation tower. The peristaltic pump feed rate is 23-28 ml / min, the atomizing disc operating frequency is 35-55 Hz, and the granulated powder is naturally cooled to room temperature after spraying to obtain yttrium oxide granulated powder. A3, Mixed pressing molding: The yttrium oxide granulated powder is placed in a mold for green body molding, with a molding pressure of 0.1-0.3 MPa. Then it is sealed and packaged and placed in a cold isostatic press with a pressing pressure of 195-205 MPa to obtain a ceramic green body. A4, Sintering: The ceramic blank is calcined at 1300℃-1600℃ for 2.5-4.5h at a heating rate of 1-4℃ / min, and then cooled in the furnace to obtain yttrium oxide ceramic material.

8. The method for preparing a ceramic material according to claim 7, characterized in that, In A1, the amount of dispersant added is 0.5% of the mass of yttrium oxide powder, the amount of binder is polyvinyl alcohol added is 0.1% of the mass of yttrium oxide powder, and the solid content of the slurry is 40%-50%.

9. The method for preparing a ceramic material according to claim 7, characterized in that, In A3, the molding pressure of the raw preform is 0.2 MPa, and the cold isostatic pressing pressure is 200 MPa.

10. The method for preparing a ceramic material according to claim 7, characterized in that, In A4, the heating rate is 2-3℃ / min, the sintering temperature is 1400℃-1500℃, and the calcination time is 3h.

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