A powder containing zirconium oxide granules and its preparation method

Abstract

This invention discloses a zirconia-containing powder and its preparation method, relating to the field of ceramic materials technology. The composite ceramic powder consists of 75 parts of silane coupling agent-modified zirconia particles, 20 parts of alumina-coated silica composite particles, and 5 parts of lithium borate-modified yttrium oxide stabilizer. The silane coupling agent-modified zirconia particles have an average particle size of 0.3 μm and a zirconia purity ≥99.9%; the alumina-coated silica composite particles have an average particle size of 0.1 μm and a theoretical alumina mass fraction of 30%; and the lithium borate-modified yttrium oxide stabilizer has an average particle size of 0.02 μm and a yttrium oxide to lithium borate mass ratio of 9:1. Testing shows that after sintering at 1350℃ for 2 hours, the composite ceramic powder of this invention achieves a relative density of 99.6%, a flexural strength of 1450 MPa, and a fracture toughness of 7.2 MPa. m1 / 2 After aging in a 134℃, 0.2MPa water vapor environment for 20 hours, the monoclinic phase content is only 2.1%, and the flexural strength retention rate is 92.5%; the powder Hall flow rate is 32s / 50g, making it suitable for high-performance structural ceramics fields such as mechanical cutting tools, bearings, and biomedical implants.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, specifically to a zirconia-containing powder suitable for high-performance structural ceramics and its preparation method. It is particularly suitable for industrial applications that require high strength, high toughness, and excellent thermal stability (such as mechanical cutting tools, bearings, and biomedical implants). It can fully leverage the phase transformation toughening advantages of zirconia while solving the problems of high sintering temperature and poor hydrothermal aging resistance of traditional zirconia ceramics. Background Technology

[0002] Zirconia ceramics are widely used in machinery, electronics, and biomedicine due to their high hardness, high strength, good wear resistance, and biocompatibility. However, traditional zirconia ceramics have three major drawbacks: first, the sintering temperature is high (usually above 1500℃), resulting in high energy consumption and an increased risk of abnormal grain growth; second, they have poor resistance to hydrothermal aging, easily undergoing a tetragonal-to-monoclinic phase transformation in humid and hot environments, leading to a sharp decline in mechanical properties; and third, their toughness still needs improvement, making them unable to withstand severe impact loads.

[0003] Existing technologies for modifying zirconia ceramics primarily focus on single-element doping or simple physical mixing, failing to achieve a synergistic design of the "matrix-toughening phase-stabilizer" relationship. For example, while simply adding alumina can improve strength, it reduces toughness; similarly, increasing yttrium oxide content can stabilize the tetragonal phase, but it lowers mechanical properties. Furthermore, zirconia particles in existing technologies tend to agglomerate, leading to internal defects in the ceramic and further affecting its performance. Therefore, developing a composite ceramic powder containing modified zirconia particles that exhibits low sintering temperature, good resistance to hydrothermal aging, and both high strength and high toughness is of great significance. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a zirconia granule powder and its preparation method, overcoming the shortcomings of existing zirconia ceramics such as high sintering temperature, poor resistance to hydrothermal aging, and insufficient toughness.

[0005] Technical solution: A zirconia granule powder, comprising the following components by weight: 75 parts of silane coupling agent modified zirconia granules, 20 parts of alumina-coated silica composite particles, and 5 parts of lithium borate-modified yttrium oxide stabilizer; the silane coupling agent modified zirconia granules have an average particle size of 0.3 μm, a zirconia purity ≥99.9%, an initial crystal form of pure tetragonal phase, and a tetragonal phase content ≥99.5% (quantitatively analyzed by X-ray diffraction), and are made from yttrium oxide pre-stabilized zirconia powder prepared by co-precipitation method, wherein the yttrium oxide pre-doping amount is 2.0 mol%; the alumina-coated silica composite particles have an average particle size of 0.1 μm, wherein the theoretical mass fraction of alumina is 30%; the lithium borate-modified yttrium oxide stabilizer has an average particle size of 0.02 μm and is prepared by mixing yttrium oxide and lithium borate at a mass ratio of 9:1.

[0006] Preferably, the silane coupling agent modified zirconia granules are prepared by the following steps: adding zirconia granules to a 5% (w / w) 3-aminopropyltriethoxysilane ethanol aqueous solution at a solid-liquid ratio of 4:1, stirring and reacting at 75°C for 2.5 h, filtering, drying at 90°C for 4 h, cooling to room temperature, and passing through a 300-mesh sieve; the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 95:5.

[0007] Preferably, the alumina-coated silica composite particles are prepared by the following steps: silica particles with an average particle size of 0.05 μm are added to deionized water to prepare a 10% (w / w) suspension, which is then ultrasonically dispersed for 30 min; based on the theoretical alumina mass fraction of 30% in the final alumina-coated silica composite particles, 2101 g of a 15% (w / w) aluminum nitrate nonahydrate solution is added dropwise per 100 g of silica particles, while simultaneously adjusting the pH value to 8.2 ± 0.1 with 10% (w / w) ammonia water. The pH value is selected based on the following: This invention has systematically studied the effect of pH value on silica... Effects of silica solubility and aluminum hydroxide precipitation uniformity: (1) When pH < 8.0, the precipitation rate of aluminum hydroxide is too fast, easily forming agglomerates, and cannot uniformly coat the silica surface; (2) When pH = 8.2 ± 0.1, the precipitation rate of aluminum hydroxide is moderate, and a uniform continuous coating layer can be formed on the silica surface, and the silica solubility is only 0.7% (as measured by inductively coupled plasma emission spectroscopy); (3) When pH > 8.5, the silica solubility rises sharply to more than 5%, causing the silica core to be severely corroded and unable to form a complete "core-shell" structure. Therefore, pH = 8.2 ± 0.1 is selected as the optimal coating pH value. After the addition is completed, continue stirring for 2 hours; transfer the mixture to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene, control the filling degree to 60%, and hydrothermally react at 180℃ for 12 hours; after the reaction is completed, cool to room temperature, filter, wash until neutral, and dry at 100℃ for 6 hours.

[0008] Preferably, the lithium borate-modified yttrium oxide stabilizer is prepared by the following steps: yttrium oxide and lithium borate are mixed at a mass ratio of 9:1, added to deionized water to prepare a suspension with a mass fraction of 20%, and ball-milled for 24 hours using zirconia balls as the ball milling medium at a ball-to-material ratio of 6:1; the ball-milled suspension is spray-dried at an inlet temperature of 220°C and an outlet temperature of 110°C; the dried powder is calcined at 900°C for 2 hours, cooled to room temperature, and then passed through a 400-mesh sieve.

[0009] A method for preparing zirconium oxide granules into powder includes the following steps: S1. Preparation of silane coupling agent modified zirconia granules: Zirconia granules are added to a 5% (w / w) 3-aminopropyltriethoxysilane ethanol aqueous solution at a solid-liquid ratio of 4:1. The mixture is stirred in a closed container at 75°C for 2.5 h, filtered, dried at 90°C for 4 h, cooled to room temperature, and then passed through a 300-mesh sieve. The volume ratio of ethanol to deionized water in the ethanol aqueous solution is 95:5. S2. Preparation of alumina-coated silica composite particles: Silica particles with an average particle size of 0.05 μm were added to deionized water to prepare a 10% (w / w) suspension, which was ultrasonically dispersed for 30 min. Based on the theoretical alumina content of 30% in the final alumina-coated silica composite particles, 2101 g of 15% (w / w) aluminum nitrate nonahydrate solution was added dropwise per 100 g of silica particles. Simultaneously, the pH value was adjusted to 8.2 ± 0.1 with 10% (w / w) ammonia water. After the addition was complete, stirring was continued for 2 h. The mixture was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene, with the filling degree controlled at 60%, and the reaction was carried out at 180℃ for 12 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed until neutral, and dried at 100℃ for 6 h. S3. Preparation of lithium borate-modified yttrium oxide stabilizer: Yttrium oxide and lithium borate were mixed at a mass ratio of 9:1 and added to deionized water to prepare a suspension with a mass fraction of 20%. Zirconia balls were used as the ball milling medium, with a ball-to-material ratio of 6:1, and the mixture was ball-milled for 24 hours. The ball-milled suspension was spray-dried at an inlet temperature of 220°C and an outlet temperature of 110°C. The dried powder was calcined at 900°C for 2 hours, cooled to room temperature, and then passed through a 400-mesh sieve. S4. Stepwise ball milling: 75 parts of silane coupling agent modified zirconia granules, 20 parts of alumina-coated silica composite particles, and 5 parts of lithium borate modified yttrium oxide stabilizer were added to a ball mill. 0.3% of ammonium polyacrylate dispersant and 0.3% of stearic acid grinding aid were added relative to the mass fraction of the mixed powder. The mixture was first ball-milled at 200 r / min for 1 hour, and then at 400 r / min for 3 hours. The ball-to-material ratio was 5:1, and the ball milling media was zirconia balls. S5. Spray granulation: Add the ball-milled mixed powder to deionized water to prepare a slurry with a mass fraction of 40%. Add 2% polyvinyl alcohol binder and 0.5% polyacrylic acid dispersant relative to the mass fraction of the mixed powder, and stir evenly. Spray granulate the slurry with an atomization pressure of 0.3 MPa, an inlet temperature of 250℃, and an outlet temperature of 120℃ to obtain composite ceramic powder with an average particle size of 50 μm.

[0010] Preferably, the zirconium oxide granule powder is dry-pressed, heated to 1200℃ at 5℃ / min and held for 1 hour, then heated to 1350℃ at 3℃ / min and held for 2 hours for sintering, resulting in a relative density ≥99.5%, flexural strength ≥1400MPa, and fracture toughness ≥7.0MPa·m. 1 / 2 .

[0011] Preferably, after the sintered sample containing zirconia granules is aged in a 134°C, 0.2MPa water vapor environment for 20 hours, the monoclinic phase content is ≤2.5% and the flexural strength retention rate is ≥90%.

[0012] Preferably, the loose packing density of the zirconium oxide granule-containing powder is ≥1.7 g / cm³. 3 Tap density ≥ 2.5 g / cm³ 3 Hall flow rate ≤35s / 50g Beneficial effects: 1. Significantly reduced sintering temperature and energy savings: The sintering temperature of traditional zirconia ceramics is usually above 1500℃. In this solution, lithium borate in the lithium borate-modified yttrium oxide stabilizer can form a low-melting-point liquid phase, promoting material diffusion during sintering. Combined with a 1200℃ pre-diffusion step, the ceramic can achieve a relative density of over 99.5% after holding at 1350℃ for 2 hours. The sintering temperature is reduced by 150℃, and energy consumption is reduced by about 20%. At the same time, the lower sintering temperature can effectively inhibit abnormal grain growth, keeping the ceramic grain size below 0.5μm, which is beneficial to improving mechanical properties.

[0013] 2. Significantly improved resistance to hydrothermal aging and extended service life: Traditional yttrium oxide-stabilized zirconia ceramics, after aging in a 134℃, 0.2MPa water vapor environment for 20 hours, typically exhibit a monoclinic phase content exceeding 10%, resulting in a flexural strength decrease of over 30%. In this solution, lithium borate in the lithium borate-modified yttrium oxide stabilizer can enter the zirconia lattice, forming a more stable solid solution. Simultaneously, alumina-coated silica composite particles can form a continuous barrier layer at the grain boundaries, inhibiting water molecule penetration. Testing shows that, under the same aging conditions, the ceramic of this invention has a monoclinic phase content of only 2.1%, a flexural strength retention rate of 92.5%, and a hydrothermal aging resistance improvement of more than 3 times.

[0014] 3. Synergistic reinforcement and toughening, balancing strength and toughness: The flexural strength of traditional zirconia ceramics is typically 800-1000 MPa, and the fracture toughness is 4-5 MPa·m. 1 / 2 In this scheme, silane molecules on the surface of silane coupling agent-modified zirconia granules can form chemical bonds with alumina-coated silica composite particles, improving interfacial bonding strength. The "core-shell" structure of the alumina-coated silica composite particles can absorb energy through mechanisms such as crack deflection and pull-out, while the phase transformation toughening effect of zirconia can further improve toughness. Testing showed that the ceramic of this invention has a flexural strength of 1450 MPa and a fracture toughness of 7.2 MPa·m. 1 / 2 These figures represent improvements of 45% and 44% respectively compared to traditional zirconia ceramics.

[0015] 4. Crystal Stability Control: This invention uses pure tetragonal zirconium oxide pre-stabilized with 2.0 mol% yttrium oxide as raw material, avoiding cracking caused by volume expansion during sintering of monoclinic zirconium oxide. Throughout the preparation process, the silane coupling agent modification temperature (75℃), hydrothermal reaction temperature (180℃), and calcination temperature (900℃) are all lower than the transformation temperature from tetragonal to monoclinic (approximately 1100℃). Furthermore, the lithium borate-modified yttrium oxide stabilizer further supplements stabilizing elements during sintering, ensuring that the tetragonal phase content in the sintered ceramic is ≥95%, providing a sufficient phase composition basis for phase transformation toughening. X-ray diffraction testing shows that the monoclinic phase content of the sintered ceramic of this invention is only 3.2%, far lower than the 8%-10% of traditional zirconium oxide ceramics.

[0016] 5. Improved powder flowability and enhanced molding quality: The composite ceramic powder after spray granulation is spherical, has good flowability, and a loose packing density of 1.8 g / cm³. 3 The tap density reaches 2.6 g / cm³. 3 It is beneficial for dry pressing and isostatic pressing, which can significantly improve the uniformity and density of the green body and reduce molding defects. Attached Figure Description

[0017] Figure 1 These are the performance test results comparing the examples and the comparative examples; Figure 2 This is a comparison of the coating effect at different pH values. Detailed Implementation

[0018] To make the technical solution of the present invention clearer, the following is combined with Figure 1 and Figure 2 The present invention will be further described in detail with reference to specific embodiments.

[0019] Example 1 S1. Preparation of silane coupling agent modified zirconia granules: Zirconia granules with an average particle size of 0.3 μm and a zirconia purity of 99.9% were added to a 5% (w / w) 3-aminopropyltriethoxysilane ethanol aqueous solution (ethanol to deionized water volume ratio 95:5) at a solid-liquid ratio of 4:1. The mixture was stirred in a closed container at 75°C for 2.5 h. After filtration, the mixture was dried at 90°C for 4 h. After cooling to room temperature, the mixture was passed through a 300-mesh sieve to obtain silane coupling agent modified zirconia granules. S2. Preparation of alumina-coated silica composite particles: Silica particles with an average particle size of 0.05 μm were added to deionized water to prepare a 10% (w / w) suspension, which was ultrasonically dispersed for 30 min. Based on the theoretical alumina content of 30% in the final alumina-coated silica composite particles, 2101 g of 15% (w / w) aluminum nitrate nonahydrate solution was added dropwise per 100 g of silica particles. Simultaneously, the pH value was adjusted to 8.2 ± 0.1 with 10% (w / w) ammonia water. After the addition was complete, stirring was continued for 2 h. The mixture was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene, with the filling degree controlled at 60%, and the reaction was carried out at 180℃ for 12 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed until neutral, and dried at 100℃ for 6 h to obtain alumina-coated silica composite particles. S3. Preparation of lithium borate-modified yttrium oxide stabilizer: Yttrium oxide and lithium borate were mixed at a mass ratio of 9:1 and added to deionized water to prepare a suspension with a mass fraction of 20%. Zirconia balls were used as the ball milling medium, with a ball-to-material ratio of 6:1, and the mixture was ball-milled for 24 hours. The ball-milled suspension was spray-dried at an inlet temperature of 220°C and an outlet temperature of 110°C. The dried powder was calcined at 900°C for 2 hours, cooled to room temperature, and then passed through a 400-mesh sieve to obtain the lithium borate-modified yttrium oxide stabilizer. S4. Stepwise ball milling: 75 parts of silane coupling agent modified zirconia granules, 20 parts of alumina-coated silica composite particles, and 5 parts of lithium borate modified yttrium oxide stabilizer were added to a ball mill. 0.3% of ammonium polyacrylate dispersant and 0.3% of stearic acid grinding aid were added relative to the mass fraction of the mixed powder. The mixture was first ball-milled at 200 r / min for 1 hour, and then at 400 r / min for 3 hours. The ball-to-material ratio was 5:1, and the ball milling media was zirconia balls. S5. Spray granulation: Add the ball-milled mixed powder to deionized water to prepare a slurry with a mass fraction of 40%. Add 2% polyvinyl alcohol binder (degree of polymerization 1750±50) and 0.5% polyacrylic acid dispersant (molecular weight 5000) relative to the mass fraction of the mixed powder, and stir evenly. Spray granulate the slurry with an atomization pressure of 0.3MPa, an inlet air temperature of 250℃, and an outlet air temperature of 120℃ to obtain composite ceramic powder with an average particle size of 50μm.

[0020] Sintering process: The composite ceramic powder is dry-pressed into a green body at a pressure of 200 MPa and held for 30 seconds. The green body is heated to 1200℃ at a rate of 5℃ / min and held for 1 hour. Then it is heated to 1350℃ at a rate of 3℃ / min and held for 2 hours. It is then cooled in the furnace.

[0021] Example 2 The difference from Example 1 is that the theoretical mass fraction of alumina in the alumina-coated silica composite particles is 35%, which corresponds to the addition of 2692g of aluminum nitrate nonahydrate solution with a mass fraction of 15% per 100g of silica particles; the remaining steps and parameters are the same.

[0022] Example 3 The difference from Example 1 is that the mass ratio of yttrium oxide to lithium borate in the lithium borate-modified yttrium oxide stabilizer is 8.5:1.5; the remaining steps and parameters are the same.

[0023] Comparative Example 1 The difference from Example 1 is that the zirconia granules were not modified with silane coupling agents and the unmodified zirconia granules were used directly; the remaining steps and parameters are the same.

[0024] Comparative Example 2 The difference from Example 1 is that uncoated silica particles and alumina particles are physically mixed at a mass ratio of 7:3 to replace alumina-coated silica composite particles; the remaining steps and parameters are the same.

[0025] Comparative Example 3 The difference from Example 1 is that unmodified yttrium oxide stabilizer is used instead of lithium borate-modified yttrium oxide stabilizer; the remaining steps and parameters are the same.

[0026] Performance testing methods Relative density: According to GB / T25995-2010, the Archimedes displacement method was used for testing, and the theoretical density was calculated by weighting the mass fraction of each component in the composite system. Bending strength: According to GB / T6569-2006, the three-point bending method was used for testing. The sample size was 3mm×4mm×36mm, the span was 30mm, and the loading rate was 0.5mm / min. Fracture toughness: According to GB / T23806-2009, the single-sided notched beam method was used for testing. The sample size was 3mm×4mm×36mm, the notch depth was 2mm, the span was 20mm, and the loading rate was 0.05mm / min. Vickers hardness: Tested according to GB / T4340.1-2009 using a Vickers hardness tester, with a load of 10 kgf and a holding time of 15 s; Hydrothermal aging resistance: According to ISO13356-2015, the sample was aged in a water vapor environment of 134℃ and 0.2MPa for 20h. The monoclinic phase content was analyzed by X-ray diffraction, and the flexural strength after aging was tested and the retention rate was calculated. Powder flowability: Tested using a Hall effect flowmeter according to GB / T1482-2010. Characterization of coating integrity: The microstructure of the composite particles was observed using transmission electron microscopy (TEM) to confirm whether a clear "core-shell" structure was formed; X-ray energy dispersive spectroscopy (EDS) was used for surface scanning analysis to verify whether aluminum elements were uniformly distributed on the surface of the silica particles; inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to test the silicon content in the supernatant after the hydrothermal reaction and to calculate the silica solubility.

[0027] Experimental results: Comparison Example 1 with Example 1: When the zirconia granules were not modified with a silane coupling agent, the relative density of the ceramic decreased by 1.4%, the flexural strength decreased by 380 MPa, and the fracture toughness decreased by 1.6 MPa·m. 1 / 2 The powder flowability deteriorated significantly. This is because unmodified zirconia granules have high surface energy, are prone to agglomeration, and have low interfacial bonding strength with alumina-coated silica composite particles. The silane coupling agent undergoes complete hydrolysis in a 95% ethanol aqueous solution to generate silanol groups, which dehydrate and form covalent bonds with the hydroxyl groups on the zirconia surface. Simultaneously, amino functional groups are introduced to react with the hydroxyl groups on the alumina surface, significantly improving interfacial bonding strength, reducing surface energy, and improving dispersibility and flowability.

[0028] Comparative Example 2 with Example 1: When physically mixed silica and alumina particles were used instead of alumina-coated silica composite particles, the flexural strength of the ceramic decreased by 270 MPa, and the fracture toughness decreased by 1.3 MPa·m. 1 / 2 This is because physically mixed particles are prone to agglomeration, failing to form a uniform "core-shell" structure and resulting in poor toughening effect. However, a hydrothermal coating process with a pH controlled at 8.2±0.1 ensures a silica core dissolution rate of <1% and a uniform alumina coating thickness (approximately 10nm), forming a complete "core-shell" structure. This allows alumina to be evenly distributed on the silica surface, forming a continuous barrier layer at grain boundaries. Simultaneously, it more effectively absorbs energy through mechanisms such as crack deflection and pull-out, thereby improving toughness.

[0029] Comparison Example 3 with Example 1: When using unmodified yttrium oxide stabilizer, the sintering temperature needs to be increased to 1500℃ to achieve a similar relative density, and the hydrothermal aging resistance is significantly reduced. Under the condition of holding at 1350℃ for 2 hours, the relative density of Comparative Example 3 is only 92.1%, which cannot meet the requirements. This is because the solid solubility of unmodified yttrium oxide stabilizer in the zirconia lattice is limited, and it cannot form a low-melting-point liquid phase to promote sintering. After calcination at 900℃, lithium borate reacts fully with yttrium oxide to form a composite stabilizer, which can enter the zirconia lattice to form a more stable solid solution, while simultaneously forming a low-melting-point liquid phase. Combined with the 1200℃ pre-diffusion step, the sintering temperature is significantly reduced, grain growth is inhibited, and the hydrothermal aging resistance is improved.

[0030] Comparison of Examples 1-3: With the increase of alumina content in the alumina-coated silica composite particles, the hardness and strength of the ceramic slightly increased, while the toughness slightly decreased. With the increase of lithium borate content, the sintering temperature of the ceramic further decreased, and the hydrothermal aging resistance further improved, but the strength slightly decreased. This indicates that by adjusting the content of each component, the performance of the ceramic can be optimized according to actual needs.

[0031] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A powder comprising zirconia-oxide-containing granules, characterized in that, It is made from the following components in parts by weight: 75 parts of silane coupling agent modified zirconia granules, 20 parts of alumina-coated silica composite particles, and 5 parts of lithium borate modified yttrium oxide stabilizer; the silane coupling agent modified zirconia granules have an average particle size of 0.3 μm, a zirconia purity ≥99.9%, an initial crystal form of pure tetragonal phase, and a tetragonal phase content ≥99.5%, and are made from yttrium oxide pre-stabilized zirconia powder prepared by co-precipitation method, wherein the yttrium oxide pre-doping amount is 2.0 mol%; the alumina-coated silica composite particles have an average particle size of 0.1 μm, wherein the theoretical mass fraction of alumina is 30%; the lithium borate modified yttrium oxide stabilizer has an average particle size of 0.02 μm and is made by mixing yttrium oxide and lithium borate in a mass ratio of 9:

1.

2. The zirconium oxide-containing pellets powder according to claim 1, characterized in that, The silane coupling agent modified zirconia granules are prepared by the following steps: the zirconia granules are added to a 5% (w / w) 3-aminopropyltriethoxysilane ethanol aqueous solution at a solid-liquid ratio of 4:1, and the mixture is stirred in a closed container at 75°C for 2.5 h. After filtration, the mixture is dried at 90°C for 4 h, cooled to room temperature, and then passed through a 300-mesh sieve. The volume ratio of ethanol to deionized water in the ethanol aqueous solution is 95:

5.

3. The zirconium oxide-containing pellets powder according to claim 1, characterized in that, The alumina-coated silica composite particles were prepared by the following steps: Silica particles with an average particle size of 0.05 μm were added to deionized water to prepare a 10% (w / w) suspension, which was then ultrasonically dispersed for 30 min. Based on a theoretical alumina content of 30% in the final alumina-coated silica composite particles, 2101 g of a 15% (w / w) aluminum nitrate nonahydrate solution was added dropwise per 100 g of silica particles, while simultaneously adjusting the pH to 8.2 ± 0.1 with 10% (w / w) ammonia. After the addition was complete, stirring was continued for 2 h. The mixture was then transferred to a polytetrafluoroethylene-lined stainless steel hydrothermal reactor, with a filling degree controlled at 60%, and hydrothermally reacted at 180℃ for 12 h. After the reaction, the mixture was cooled to room temperature, filtered, washed until neutral, and dried at 100℃ for 6 h.

4. The powder containing zirconium oxide granules according to claim 1, characterized in that, The lithium borate-modified yttrium oxide stabilizer is prepared by the following steps: yttrium oxide and lithium borate are mixed at a mass ratio of 9:1, added to deionized water to prepare a suspension with a mass fraction of 20%, and milled for 24 hours using zirconia balls as the ball milling medium at a ball-to-material ratio of 6:1; the milled suspension is then spray-dried at an inlet temperature of 220°C and an outlet temperature of 110°C; the dried powder is calcined at 900°C for 2 hours, cooled to room temperature, and then passed through a 400-mesh sieve.

5. A process for the preparation of the powder of zirconium oxide-containing granules according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Preparation of silane coupling agent modified zirconia granules: Zirconia granules are added to a 5% (w / w) 3-aminopropyltriethoxysilane ethanol aqueous solution at a solid-liquid ratio of 4:

1. The mixture is stirred in a closed container at 75°C for 2.5 h, filtered, dried at 90°C for 4 h, cooled to room temperature, and then passed through a 300-mesh sieve. The volume ratio of ethanol to deionized water in the ethanol aqueous solution is 95:

5. S2. Preparation of alumina-coated silica composite particles: Silica particles with an average particle size of 0.05 μm were added to deionized water to prepare a 10% (w / w) suspension, which was ultrasonically dispersed for 30 min. Based on the theoretical alumina content of 30% in the final alumina-coated silica composite particles, 2101 g of 15% (w / w) aluminum nitrate nonahydrate solution was added dropwise per 100 g of silica particles. Simultaneously, the pH value was adjusted to 8.2 ± 0.1 with 10% (w / w) ammonia water. After the addition was complete, stirring was continued for 2 h. The mixture was transferred to a stainless steel hydrothermal reactor lined with polytetrafluoroethylene, with the filling degree controlled at 60%, and the reaction was carried out at 180℃ for 12 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed until neutral, and dried at 100℃ for 6 h. S3. Preparation of lithium borate-modified yttrium oxide stabilizer: Yttrium oxide and lithium borate were mixed at a mass ratio of 9:1 and added to deionized water to prepare a suspension with a mass fraction of 20%. Zirconia balls were used as the ball milling medium, with a ball-to-material ratio of 6:1, and the mixture was ball-milled for 24 hours. The ball-milled suspension was spray-dried at an inlet temperature of 220°C and an outlet temperature of 110°C. The dried powder was calcined at 900°C for 2 hours, cooled to room temperature, and then passed through a 400-mesh sieve. S4. Stepwise ball milling: 75 parts of silane coupling agent modified zirconia granules, 20 parts of alumina-coated silica composite particles, and 5 parts of lithium borate modified yttrium oxide stabilizer were added to a ball mill. 0.3% of ammonium polyacrylate dispersant and 0.3% of stearic acid grinding aid were added relative to the mass fraction of the mixed powder. The mixture was first ball-milled at 200 r / min for 1 hour, and then at 400 r / min for 3 hours. The ball-to-material ratio was 5:1, and the ball milling media was zirconia balls. S5. Spray granulation: Add the ball-milled mixed powder to deionized water to prepare a slurry with a mass fraction of 40%. Add 2% polyvinyl alcohol binder and 0.5% polyacrylic acid dispersant relative to the mass fraction of the mixed powder, and stir evenly. Spray granulate the slurry with an atomization pressure of 0.3 MPa, an inlet temperature of 250℃, and an outlet temperature of 120℃ to obtain composite ceramic powder with an average particle size of 50 μm.

6. The zirconium oxide-containing pellets powder according to claim 1, characterized in that, The zirconium oxide granule powder is dry-pressed, then heated to 1200℃ at a rate of 5℃ / min and held for 1 hour, followed by sintering at 1350℃ at a rate of 3℃ / min and held for 2 hours. The resulting powder has a relative density ≥99.5%, flexural strength ≥1400MPa, and fracture toughness ≥7.0MPa·m. 1 / 2 .

7. The zirconium oxide-containing pellets powder according to claim 1, characterized in that, After the sintered sample containing zirconia granules was aged in a 134°C, 0.2MPa water vapor environment for 20 hours, the monoclinic phase content was ≤2.5% and the flexural strength retention rate was ≥90%.

8. The zirconium oxide-containing pellets powder according to claim 1, characterized in that, The loose bulk density of the zirconium oxide granules in the powder is ≥1.7 g / cm³. 3 Tap density ≥ 2.5 g / cm³ 3 Hall flow rate ≤35s / 50g.

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