Zirconium oxide toughened aluminum oxide ceramic powder as well as preparation method and application thereof

Abstract

The invention relates to zirconium oxide toughened aluminum oxide ceramic powder as well as a preparation method and application thereof. The invention researches and develops a modification preparation method which combines precise proportioning, multi-step PH value regulation and control, a specific composite coating reagent and a controllable aging process, ensures the stability of slurry by defining the solid-to-liquid ratio of (50-200): (100-1500), and can simultaneously realize uniform dispersion of powder, strong interface combination and synergistic improvement of mechanical property and chemical stability. The mechanical property, dispersity and chemical stability of the zirconium oxide toughened aluminum oxide ceramic powder are remarkably improved through the steps of pretreatment of the aluminum oxide powder, compound dispersion of the aluminum oxide powder and the modified zirconium oxide powder, doping of the modifier, high-temperature sintering post-treatment and the like.

Description

Technical Field

[0001] This invention relates to the field of ceramic material preparation technology, and in particular to a zirconia-toughened alumina ceramic powder, its preparation method, and its application. Background Technology

[0002] Zirconia-toughened alumina ceramic (ZTA) is a high-performance composite ceramic material that combines the high strength and hardness of alumina ceramics with the high toughness of zirconia ceramics. It has wide applications in aerospace engine components, artificial joints in medical devices, and bearings in precision machinery. However, traditional ZTA powder preparation often suffers from problems such as uneven powder dispersion, severe particle agglomeration, and poor interfacial bonding. Furthermore, the lack of standardized water-to-powder ratio control leads to large fluctuations in slurry concentration, further affecting the mechanical property stability of the final ceramic material and making it difficult to meet the stringent performance requirements of high-end applications.

[0003] Currently, existing modification methods for zirconia-toughened alumina ceramic powders mostly focus on single surface modification or simple mixing and doping, such as using only silane coupling agents to treat the surface of zirconia powder, or directly mixing and sintering zirconia and alumina powders. These methods not only fail to solve the problems of powder dispersibility and interfacial bonding, but also neglect the water-to-material ratio, resulting in poor controllability in the slurry preparation process. An excessively high water-to-material ratio can easily lead to increased energy consumption in subsequent drying and exacerbate powder agglomeration, while an excessively low water-to-material ratio will result in poor slurry fluidity and difficulty in uniformly dispersing the reactants, affecting the coating modification effect. In addition, existing processes lack control over the post-coating aging process, making it difficult to form a uniform and stable coating layer, further affecting the powder properties.

[0004] Chinese patent CN109440051A discloses an alumina ceramic coating with high hardness, high wear resistance, and high toughness, and its preparation method. The method includes: (1.1) selecting a substrate; (1.2) pre-treating the substrate by sandblasting or grinding; (1.3) preparing alumina raw material powder; (1.4) heating the alumina nano-sintered powder to a molten state; and (1.5) spraying alumina nano-liquid material. Although this method incorporates zirconium oxide into alumina, its method mainly involves physical mixing or simple co-precipitation / hydrothermal methods to prepare composite powders, lacking systematic and structured coating modification of the powder surface. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies, such as uneven dispersion, poor interfacial bonding, insufficient mechanical properties and chemical stability of zirconia-toughened alumina ceramic powder, and slurry instability caused by uncontrolled water-to-material ratio. This invention provides a zirconia-toughened alumina ceramic powder, its preparation method, and its applications. This invention develops a modified preparation method that combines precise ingredient proportioning, multi-step pH control, specific composite coating reagents, and a controllable aging process, while maintaining a defined solid-liquid ratio of 50-200:100-1500 to ensure slurry stability. This method simultaneously achieves uniform powder dispersion, strong interfacial bonding, and synergistic improvement in mechanical properties and chemical stability.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing zirconia-toughened alumina ceramic powder, the specific steps of which are as follows: S1. Alumina powder and zirconium oxide powder are pretreated separately and then mixed to obtain a mixed powder slurry; S2. Add the mixed powder slurry obtained in step S1 to deionized water, adjust the pH to obtain the slurry; S3. Add a dispersant to the slurry obtained in step S2 and then stir and disperse to obtain a dispersed slurry; S4. Add hafnium salt, ammonium bicarbonate and chromium salt to the dispersed slurry obtained in step S3 in sequence, and stir to obtain the coated slurry. S5. Adjust the pH of the coated slurry obtained in step S4, stir and let it stand for aging to obtain the aged slurry, and then dry it to obtain the coated and modified composite powder. S6. Add the coated and modified composite powder obtained in step S5 to deionized water, stir and dry it using a spray drying device to obtain doped composite powder particles. S7. The doped composite powder particles obtained in step S6 are sintered at high temperature in an inert gas atmosphere, and then crushed to obtain zirconia toughened alumina ceramic powder.

[0007] Further, in step S1, the preparation method of the mixed powder slurry is as follows: S1-1. Place the alumina powder in deionized water, add a dispersant, and then ultrasonically disperse it. After filtration and drying, the pretreated alumina powder is obtained. S1-2. Zirconia powder is placed in deionized water and ultrasonically dispersed to obtain pretreated zirconia powder slurry; S1-3. The pretreated alumina powder obtained in step S1-1 and the pretreated zirconia powder obtained in step S1-2 are mixed to obtain a mixed powder slurry.

[0008] Furthermore, in step S1-1, the particle size of the alumina powder is 0.5-2 μm.

[0009] Furthermore, in step S1-1, the mass ratio of the alumina powder to deionized water is 0.5~2:1~15.

[0010] Furthermore, in step S1-1, the mass ratio of the alumina powder to the dispersant is 50~200:0.25~4.

[0011] Furthermore, in step S1-1, the conditions for ultrasonic dispersion are: temperature of 20-60℃, power of 300-500W, stirring rate of 200-300r / min, and time of 20-40min.

[0012] Furthermore, in step S1-1, the drying temperature is 80-100℃ and the drying time is 4-12h.

[0013] Furthermore, in steps S1-2, the particle size of the zirconium oxide powder is 0.1-0.5 μm.

[0014] Furthermore, in steps S1-2, the mass ratio of the zirconium oxide powder to deionized water is 0.5~2:1~15.

[0015] Furthermore, in steps S1-2, the conditions for ultrasonic dispersion are: temperature of 20-60℃, power of 300-500W, time of 3-6h, and stirring rate of 200-300r / min, to ensure a uniform solid-liquid ratio.

[0016] Furthermore, in steps S1-3, the mass ratio of alumina powder to zirconium oxide powder is 65~80:35~20.

[0017] Further, in step S2, the mass ratio of the mixed powder slurry to deionized water is 0.5~2:1~15.

[0018] Further, in step S2, the pH is adjusted to 4-6, and the pH adjusting reagent includes nitric acid or ammonium hydroxide solution, the concentration of which is 0.1-0.4 mol / L.

[0019] Further, in step S3, the dispersant is selected from any one or more of ammonium polyacrylate, sodium polyacrylate, sodium hexametaphosphate, ammonium hexametaphosphate, ammonium citrate, or ammonium citrate.

[0020] Further, in step S3, the mass ratio of the dispersant to the mixed powder slurry is 0.5~1:100.

[0021] Further, in step S3, the stirring temperature is 20-60℃, the stirring time is 30-60min, and the stirring speed is 300-600r / min.

[0022] Further, in step S4, the hafnium salt is selected from any one or more of hafnium chloride or hafnium nitrate, and the hafnium salt is of analytical grade.

[0023] Furthermore, in step S4, the ammonium bicarbonate has a purity of ≥99.5%.

[0024] Further, in step S4, the chromium salt is selected from any one or more of chromium nitrate or chromium chloride, and the purity of the chromium salt is ≥98%.

[0025] Further, in step S4, the mass ratio of the hafnium salt, ammonium bicarbonate, chromium salt and zirconium oxide powder in step S1 is 5~10:3~8:2~5:100.

[0026] Furthermore, in step S4, the stirring temperature is 40-60℃, the stirring time is 1-3h, and the stirring speed is 300-600r / min.

[0027] Furthermore, in step S4, if the concentration of the dispersed slurry changes due to the reaction during stirring, deionized water can be added at a solid-liquid mass ratio of 50~200:100~1500 to maintain a stable water-to-material ratio. When adding deionized water, it should be added dropwise, and the amount added each time should not exceed 5-10% of the total water volume to prevent sudden changes in slurry concentration.

[0028] Further, in step S5, the pH adjustment range is 7-9, and the pH adjustment reagent includes nitric acid or ammonium hydroxide solution, the concentration of which is 0.1-0.4 mol / L.

[0029] Further, in step S5, the stirring temperature is room temperature (20-25℃), the stirring time is 30-120 min, and the stirring speed is 300-500 r / min.

[0030] Furthermore, in step S5, the settling and aging time is 1-3 hours.

[0031] Furthermore, in step S5, the drying temperature is 60-100℃, and the drying time is 8-15 hours.

[0032] Further, in step S6, the mass ratio of the coated and modified composite powder to deionized water is 0.5~2:1~15.

[0033] Further, in step S6, the stirring temperature is room temperature (20-25℃), the stirring time is 2-4 hours, and the stirring speed is 300-500 r / min.

[0034] Furthermore, in step S6, the inlet air temperature of the spray drying equipment is 180-250℃, and the outlet temperature is 80-120℃.

[0035] Further, in step S7, the inert gas atmosphere includes a nitrogen atmosphere and / or an argon atmosphere, and the flow rate of the inert gas is 0.5-1.5 L / min.

[0036] Furthermore, in step S7, the heating rate of the high-temperature sintering is 2-3℃ / min, the temperature of the high-temperature sintering is 1400-1600℃, and the holding time of the high-temperature sintering is 2-4h.

[0037] The present invention also provides a zirconia-toughened alumina ceramic powder, which is prepared by the above method.

[0038] In addition, the present invention also provides an application of zirconia-toughened alumina ceramic powder in aerospace, medical devices, precision machinery and other fields.

[0039] Furthermore, the aerospace field includes engine components, thermal protection systems, and structural components. The medical device field includes orthopedic implants, dental prostheses, and surgical instruments. The field of precision machinery includes wear-resistant parts, cutting tools, and precision molds.

[0040] The principle of this invention is as follows: This invention provides a method for preparing zirconia-toughened alumina ceramic powder, comprising eight key steps: powder pretreatment and batching, first pH adjustment, dispersant addition, zirconia coating, second pH adjustment and stirring aging, filtration and drying, doping modification, high-temperature sintering and post-treatment. In key steps such as zirconia pretreatment, mixed slurry preparation, and doping modified slurry preparation, a material-to-water ratio of 50~200:100~1500 (i.e., solid-liquid mass ratio of 0.5~2:1~15) is explicitly adopted.

[0041] In the powder pretreatment and batching steps, deionized water is added to the zirconium oxide powder during ultrasonic dispersion at a water-to-powder ratio of 50~200:100~1500 (i.e., solid-liquid mass ratio of 0.5~2:1~15). This ratio ensures that the powder is fully dispersed, avoids particle agglomeration due to insufficient water, and prevents excessive water from increasing the burden on subsequent processing. The alumina powder undergoes ultrasonic dispersion-coating-filtration-drying pretreatment to remove surface impurities and agglomerated particles. It is precisely batched according to a specific mass ratio and a stable material-to-water ratio is maintained to lay a uniform raw material system foundation for subsequent composite modification.

[0042] In the first pH adjustment step, the mixed powder slurry should be prepared strictly according to a water-to-solid ratio of 50~200:100~1500 (i.e., solid-liquid mass ratio of 0.5~2:1~15). At this concentration, the slurry has suitable fluidity, which facilitates the uniform diffusion of reagents during pH adjustment and avoids local pH imbalance caused by excessively concentrated slurry. Adjusting the pH to an acidic environment of 4-6 is beneficial for the subsequent dispersant to fully interact with the powder surface, improving the dispersion effect. At the same time, it creates suitable conditions for the dissolution and reaction of the coating reagent, avoiding premature agglomeration of powder caused by an alkaline environment.

[0043] In the dispersant addition step, ammonium polyacrylate is selected as the dispersant. In a slurry system with a water-to-solid ratio of 50~200:100~1500 (i.e., a solid-liquid mass ratio of 0.5~2:1~15), the dispersant molecules can be more uniformly adsorbed onto the powder surface, forming a stable steric hindrance effect. Combined with stirring at specific temperatures and speeds, this further inhibits particle agglomeration and provides a uniform reaction system for subsequent coating modification. The stable water-to-solid ratio ensures that the dispersant concentration is controllable, avoiding unstable dispersion effects due to fluctuations in slurry concentration.

[0044] The zirconia coating process employs a composite reagent of hafnium chloride, ammonium bicarbonate, and chromium nitrate nonahydrate. It is specified that if the slurry concentration changes due to water loss during the reaction, deionized water can be added at a water-to-material ratio of 50-200:100-1500 (i.e., a solid-liquid mass ratio of 0.5-2:1-15). Hafnium chloride forms a dense hafnium oxide coating layer on the zirconia surface, improving the powder's high-temperature resistance. Ammonium bicarbonate, as a slow-release agent, slowly releases ammonium ions, regulating the reaction rate and preventing uneven coating formation caused by excessively rapid coating. Chromium ions in chromium nitrate nonahydrate can combine with hydroxyl groups on the zirconia surface, enhancing the adhesion between the coating layer and the substrate. A stable water-to-material ratio provides a stable environment for the synergistic reaction of these three components, ensuring uniform coating growth and preventing uneven coating thickness due to sudden changes in slurry concentration.

[0045] In the second pH adjustment and stirring aging step, the pH value is adjusted to neutral and slightly alkaline (7-9) in the slurry system with a water-to-solid ratio of 50~200:100~1500 (i.e., solid-liquid mass ratio of 0.5~2:1~15). This can smoothly terminate the coating reaction and avoid pH value control failure due to slurry concentration fluctuations. Stirring at room temperature for 30 minutes can ensure that the pH value is evenly distributed in the stable slurry system, avoiding local acid-base imbalance that affects the quality of the coating layer. Static aging for 1-3 hours allows the coating layer to fully crystallize and stabilize in a stable slurry environment, reducing the risk of coating layer detachment during subsequent processing.

[0046] In the doping modification step, a slurry of coated modified composite powder and deionized water is prepared at a water-to-material ratio of 50~200:100~1500 (i.e., solid-liquid mass ratio of 0.5~2:1~15). This ratio is to ensure that the dopant agglomerates due to insufficient water, which would affect the doping effect of the final powder. A stable water-to-material ratio also provides a suitable slurry concentration for the spray drying stage, ensuring that uniformly sized doped composite powder particles are obtained after drying.

[0047] The filtration and drying steps employ low-temperature drying at 60-100℃ for 8-15 hours or more. Compared to traditional high-temperature drying, this avoids cracking of the coating layer due to sudden temperature increases, while slowly removing moisture to ensure the stability of the filter cake's internal structure, providing high-quality composite powder raw materials for subsequent high-temperature sintering. In the high-temperature sintering and post-treatment steps, high-temperature sintering under inert gas protection forms a dense ceramic structure. Finally, through crushing and sieving, high-performance modified powder is obtained. The stable water-to-material ratio control in each stage ensures uniform shrinkage and densification of the powder during sintering, avoiding structural defects after sintering due to uneven slurry distribution in the early stages.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention treats the surfaces of zirconium oxide and alumina powders using ultrasonic chemical precipitation to form nanoscale surface-modified powders. These powders are then pre-calcined to create a stable, dense core-shell structure. After uniform mixing, the pre-calcined nanoparticles are spray-dried, cold-pressed, calcined, and thermally sintered to densify, resulting in a high-wear-resistant, high-toughness alumina ceramic structure. This invention differs from most methods for preparing high-wear-resistant, high-toughness zirconium oxide ceramics. Current mainstream methods involve high-energy grinding, mixing, molding, and sintering, which struggle to ensure uniform mixing of the two powders, leading to fluctuations in ceramic properties and affecting performance. This invention, through ultrasonic core-shell coating, effectively addresses the agglomeration problem of nano-zirconia powders. Furthermore, the treated powders enhance sintering activity, allowing for lower sintering temperatures and densification, significantly reducing energy consumption and costs.

[0049] This invention significantly improves the mechanical properties, dispersibility, and chemical stability of zirconia-toughened alumina ceramic powder through steps such as pretreatment of alumina powder, composite dispersion with modified zirconia powder, doping with modifiers, and high-temperature sintering post-treatment. The prepared ceramic powder can be widely used in aerospace, medical devices, precision machinery, and other fields, possessing high practical value and market prospects. Detailed Implementation

[0050] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0051] This invention provides a method for preparing zirconia-toughened alumina ceramic powder, the specific steps of which are as follows: (1) Powder pretreatment and batching: 50-200g of alumina powder with a particle size of 0.5-2μm was placed in 100-1500g of deionized water, and 0.5%-2% of ultrasonic dispersant by mass of alumina powder was added. The mixture was ultrasonically dispersed for 20-40min at a temperature of 20-60℃ and a power of 300-500W. The mixture was then coated, stirred, and filtered. After filtration, the powder was dried at 80-100℃ for 4-12h to obtain pretreated alumina powder. Zirconia powder with a particle size of 0.1-0.5μm was placed in deionized water and added at a solid-liquid mass ratio of 50-200:100-1500. After ultrasonic stirring and dispersion for 3-6 hours, pretreated zirconia powder was obtained for later use. Pretreated alumina powder and pretreated zirconia powder are mixed at a mass ratio of 65~80:35~20 to obtain a mixed powder slurry; (2) First pH adjustment: Add deionized water to the mixed powder slurry obtained in step (1) at a material-to-water ratio of 50~200:100~1500 (i.e., solid-liquid mass ratio of 0.5~2:1~15) to prepare the slurry. Use nitric acid or ammonium hydroxide solution with a concentration of 0.1-0.4mol / L to adjust the pH value of the slurry to 4-6. The pH value adjustment accuracy is ±0.2. During the adjustment process, stir the slurry slowly at a speed of 100-300r / min to avoid local pH value fluctuations affecting the stability of the water-to-material ratio. (3) Addition of dispersant: Add 0.5%-1% of a dispersant to the slurry after adjusting the pH value in step (2), and stir and disperse it for 30-60 minutes at a temperature of 20-60℃ and a rotation speed of 300-600r / min to obtain the dispersed slurry. (4) Zirconia coating: Add hafnium chloride, ammonium bicarbonate, and chromium nitrate nonahydrate to the slurry dispersed in step (3) at 5-10% of the mass of zirconium oxide powder, and continue stirring for 1-3 hours to obtain the coated slurry. During this period, keep the temperature at 40-60℃ and the rotation speed constant. If the concentration of the slurry changes due to the reaction, deionized water can be added at a solid-liquid mass ratio of 50-200:100-1500 to maintain a stable water-to-material ratio. When adding deionized water, use a dripping method, and the amount added each time should not exceed 5-10% of the total water volume to prevent sudden changes in the slurry concentration. (5) Second pH adjustment and stirring aging: Using a nitric acid or ammonium hydroxide solution with a concentration of 0.1-0.4 mol / L, the pH value of the slurry coated in step (4) is adjusted to 7-9. Then, at room temperature (20-25℃), it is stirred at a speed of 300-500 r / min for 30-120 min. After that, it is left to stand for 1-3 h for aging. Vibration interference should be avoided during the aging process. The slurry state is observed every 20 min during the aging period to ensure that there is no stratification. The aged slurry is obtained. (6) Filtration and drying: The aged slurry from step (5) is filtered by vacuum filtration using a combination of a Buchner funnel and a vacuum pump. The filter cake thickness is controlled at 5-10 mm, and the vacuum filtration negative pressure is -0.06 to -0.08 MPa to avoid damage to the filter cake structure due to excessive pressure. The filter cake is collected and placed in a constant temperature drying oven at 60-100℃ for 8-15 hours or more to obtain coated modified composite powder. (7) Doping modification: The coated modified composite powder obtained in step (6) is mixed with deionized water. Deionized water is added at a solid-liquid mass ratio of 50~200:100~1500 to prepare a slurry. After stirring for 2-4 hours, it is dried using a spray drying device (inlet air temperature 180-250℃, outlet temperature 80-120℃) to obtain doped composite powder particles. A paddle mixer is used when mixing the slurry. The paddle is inserted to a depth of 2 / 3 of the slurry height to ensure a uniform water-to-material ratio and prevent sediment buildup. (8) High-temperature sintering and post-treatment: The doped composite powder particles obtained in step (7) are placed in a sintering furnace and heated to 1400-1600℃ at a heating rate of 2-3℃ / min under the protection of nitrogen or argon gas with a flow rate of 0.5-1.5L / min. The temperature is held for 2-4 hours and then naturally cooled to room temperature. The sintered block material is then crushed and passed through a 200-400 mesh sieve to obtain zirconia toughened alumina ceramic modified powder.

[0052] Unless otherwise specified in the embodiments, the raw materials or processing techniques used are conventional commercially available products or conventional processing techniques in the art. The following detailed description of some embodiments of the present invention is provided in conjunction with specific examples. Unless otherwise agreed, the following embodiments and features described herein can be combined with each other.

[0053] Example 1 This embodiment provides a method for preparing zirconia-toughened alumina ceramic powder, the specific steps of which are as follows: (1) Powder pretreatment and batching: 50-200g of alumina powder with a particle size of 0.5-2μm was placed in 100-1500g of deionized water, and 0.5%-2% of ultrasonic dispersant by mass of alumina powder was added. The mixture was ultrasonically dispersed for 20-40min at a temperature of 20-60℃ and a power of 300-500W. The mixture was then coated, stirred, and filtered. After filtration, the powder was dried at 80-100℃ for 4-12h to obtain pretreated alumina powder. Zirconia powder with a particle size of 0.1-0.5μm was placed in deionized water and added at a solid-liquid mass ratio of 50-200:100-1500. After ultrasonic stirring and dispersion for 3-6 hours, pretreated zirconia powder was obtained for later use. Pretreated alumina powder and pretreated zirconia powder are mixed at a mass ratio of 65~80:35~20 to obtain a mixed powder slurry; (2) First pH adjustment: Add deionized water to the mixed powder slurry obtained in step (1) at a material-to-water ratio of 50~200:100~1500 (i.e., solid-liquid mass ratio of 0.5~2:1~15) to prepare the slurry. Use nitric acid or ammonium hydroxide solution with a concentration of 0.1-0.4mol / L to adjust the pH value of the slurry to 4-6. The pH value adjustment accuracy is ±0.2. During the adjustment process, stir the slurry slowly at a speed of 100-300r / min to avoid local pH value fluctuations affecting the stability of the water-to-material ratio. (3) Addition of dispersant: Add 0.5%-1% of a dispersant to the slurry after adjusting the pH value in step (2), and stir and disperse it for 30-60 minutes at a temperature of 20-60℃ and a rotation speed of 300-600r / min to obtain the dispersed slurry. (4) Nanopowder coating: Add hafnium chloride, ammonium bicarbonate, and chromium nitrate nonahydrate to the slurry dispersed in step (3) at 5-10% of the mass of zirconium oxide powder, and continue stirring for 1-3 hours to obtain the coated slurry. During this period, keep the temperature at 40-60℃ and the rotation speed constant. If the concentration of the slurry changes due to the reaction, deionized water can be added at a solid-liquid mass ratio of 50-200:100-1500 to maintain a stable water-to-material ratio. When adding deionized water, use a dripping method, and the amount added each time should not exceed 5-10% of the total water volume to prevent sudden changes in the slurry concentration. (5) Second pH adjustment and stirring aging: Using a nitric acid or ammonium hydroxide solution with a concentration of 0.1-0.4 mol / L, the pH value of the slurry coated in step (4) is adjusted to 7-9. Then, at room temperature (20-25℃), it is stirred at a speed of 300-500 r / min for 30-120 min. After that, it is left to stand for 1-3 h for aging. Vibration interference should be avoided during the aging process. The slurry state is observed every 20 min during the aging period to ensure that there is no stratification. The aged slurry is obtained. (6) Filtration and drying: The aged slurry from step (5) is filtered by vacuum filtration using a combination of a Buchner funnel and a vacuum pump. The filter cake thickness is controlled at 5-10 mm, and the vacuum filtration negative pressure is -0.06 to -0.08 MPa to avoid damage to the filter cake structure due to excessive pressure. The filter cake is collected and placed in a constant temperature drying oven at 60-100℃ for 8-15 hours or more to obtain coated modified composite powder. (7) Doping modification: The coated modified composite powder obtained in step (6) is mixed with deionized water. Deionized water is added at a solid-liquid mass ratio of 50~200:100~1500 to prepare a slurry. After stirring for 2-4 hours, it is dried using a spray drying device (inlet air temperature 180-250℃, outlet temperature 80-120℃) to obtain doped composite powder particles. A paddle mixer is used when mixing the slurry. The paddle is inserted to a depth of 2 / 3 of the slurry height to ensure a uniform water-to-material ratio and prevent sediment buildup. (8) High-temperature sintering and post-treatment: The doped composite powder particles obtained in step (7) are placed in a sintering furnace and heated to 1400-1600℃ at a heating rate of 2-3℃ / min under the protection of nitrogen or argon gas with a flow rate of 0.5-1.5L / min. The temperature is held for 2-4 hours and then naturally cooled to room temperature. The sintered block material is then crushed and passed through a 200-400 mesh sieve to obtain zirconia toughened alumina ceramic modified powder.

[0054] Table 1 Raw material parameters in Examples 1-5 Table 2 Preparation process parameters in Examples 1-5 Table 3 Performance test results of Examples 1-5 The data comparison and optimal parameter analysis are as follows: 1. The impact of key parameters on performance (1) Effect of raw material particle size and ratio: As the particle size of alumina powder increases from 0.5 μm to 2.0 μm and the particle size of zirconia powder increases from 0.1 μm to 0.5 μm, the overall performance shows a trend of first increasing and then stabilizing. Among them, the bending strength and fracture toughness of Example 3 (alumina 0.8 μm, zirconia 0.2 μm, ratio 80:20) are better than those of examples with excessively large or small particle sizes, indicating that raw materials with medium particle size are easier to achieve uniform dispersion and reduce agglomeration defects; while a high proportion of zirconia (such as 65:35 in Example 5) can improve toughness, but will lead to a slight decrease in hardness, while a low proportion (such as 80:20 in Example 3) can ensure both toughness and strength and hardness.

[0055] (2) Effect of ultrasonic dispersion and pH value: When the ultrasonic dispersion power is 400-480W (Examples 1-3), the performance is better than that of 300-350W (Examples 4-5), indicating that the ultrasonic dispersion with higher power can more effectively break up particle agglomeration; the performance of the first pH adjustment in the range of 5-6 (Examples 2-3, 5) is better than that of pH=4 (Example 1) and pH=4.5 (Example 4), indicating that a weakly acidic environment is more conducive to the adsorption of dispersant and improves the stability of slurry.

[0056] (3) Influence of sintering process: When the sintering temperature is 1500-1550℃ and the holding time is 2.5-3h (Examples 2-3), the bulk density, strength and hardness all reach a high level. Too low a temperature (1400-1450℃, Examples 1 and 4) will lead to insufficient sintering and low density and strength; too high a temperature (1600℃, Example 5) can increase the density, but will cause excessive grain growth and slow down the growth of toughness; when the protective gas flow rate is 1.0-1.2L / min (Examples 2-3), the anti-oxidation effect is the best and the mass loss rate is the lowest. Too low a flow rate (0.5-0.8L / min, Examples 1 and 4) will result in insufficient protection, and too high a flow rate (1.5L / min, Example 5) will increase the cost and have no significant performance improvement.

[0057] 2. Determining the optimal parameters Based on the performance data from all embodiments, the parameters of Embodiment 3 are the optimal solution, as detailed below: (1) Raw material parameters: alumina powder with a particle size of 0.8 μm and zirconium oxide powder with a particle size of 0.2 μm, with a mass ratio of 80:20; (2) Preparation process parameters: ultrasonic dispersion power 400W, pH value adjusted to 6 for the first time, dispersant (ammonium citrate) addition amount 1%, sintering temperature 1550℃, heat preservation for 2.5h, nitrogen flow rate 1.2L / min; (3) Core advantages: Under these parameters, the bending strength (850MPa), fracture toughness (9.8MPa・m^(1 / 2)), and Vickers hardness (18.8GPa) are the highest among all embodiments, and the bulk density (4.18g / cm³) is the highest. 3 It has a high level of chemical stability (0.07% mass loss rate), and takes into account both mechanical properties and corrosion resistance, which can better meet the stringent requirements of high-end fields such as aerospace and medical devices.

[0058] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for producing a zirconia toughened alumina ceramic powder, characterized by, The specific steps are as follows: S1, the alumina powder and zirconia powder are pretreated respectively, and then mixed to obtain a mixed powder slurry; S2, the mixed powder slurry obtained in step S1 is added to deionized water, and after adjusting the PH, a slurry is obtained; S3, a dispersing agent is added to the slurry obtained in step S2, and then stirred and dispersed to obtain a dispersed slurry; S4, hafnium salt, ammonium bicarbonate and chromium salt are added to the dispersed slurry obtained in step S3 in sequence, and then stirred to obtain a coated slurry; S5, the PH of the coated slurry obtained in step S4 is adjusted, and then stirred and aged to obtain an aged slurry, which is dried to obtain a coated modified composite powder; S6, the coated modified composite powder obtained in step S5 is added to deionized water, stirred, and then dried by a spray drying device to obtain a doped composite powder particle; S7, the doped composite powder particle obtained in step S6 is sintered at high temperature in an inert gas atmosphere, and then crushed to obtain a zirconia toughened alumina ceramic powder.

2. The method for preparing zirconia-toughened alumina ceramic powder according to claim 1, characterized in that, In step S1, the preparation method of the mixed powder slurry is as follows: S1-1, the alumina powder is placed in deionized water, a dispersing agent is added, and then ultrasonic dispersion is carried out, and after filtration and drying, a pretreated alumina powder is obtained; S1-2, the zirconia powder is placed in deionized water and ultrasonic dispersion is carried out to obtain a pretreated zirconia powder slurry; S1-3, the pretreated alumina powder obtained in step S1-1 and the pretreated zirconia powder obtained in step S1-2 are mixed to obtain a mixed powder slurry.

3. The method for preparing zirconia-toughened alumina ceramic powder according to claim 2, characterized in that, In step S1-1, the particle size of the alumina powder is 0.5-2 μm; In step S1-1, the mass ratio of the alumina powder and deionized water is 0.5-2:1-15; In step S1-1, the mass ratio of the alumina powder and the dispersing agent is 50-200:0.25-4; In step S1-2, the particle size of the zirconia powder is 0.1-0.5 μm; In step S1-2, the mass ratio of the zirconia powder and deionized water is 0.5-2:1-15; In step S1-3, the mass ratio of the alumina powder and the zirconia powder is 65-80:35-20.

4. The method for preparing zirconia-toughened alumina ceramic powder according to claim 1, characterized in that, In step S2, the mass ratio of the mixed powder slurry and deionized water is 0.5-2:1-15; The PH is adjusted to 4-6, the PH adjusting agent includes nitric acid or ammonium hydroxide solution, and the concentration of the nitric acid or ammonium hydroxide solution is 0.1-0.4 mol / L.

5. The method for preparing zirconia-toughened alumina ceramic powder according to claim 1, characterized in that, In step S3, the dispersing agent is selected from any one or more of polyacrylammonium, polyacrylic acid sodium, sodium hexametaphosphate, ammonium hexametaphosphate, ammonium citrate or ammonium citrate; The mass ratio of the dispersing agent and the mixed powder slurry is 0.5-1:

100.

6. The method for preparing zirconia-toughened alumina ceramic powder according to claim 1, characterized in that, In step S4, the hafnium salt is selected from any one or more of hafnium chloride or hafnium nitrate, and the chromium salt is selected from any one or more of chromium nitrate or chromium chloride; The mass ratio of the hafnium salt, ammonium bicarbonate, chromium salt and zirconia powder in step S1 is 5-10:3-8:2-5:

100.

7. The method for preparing zirconia-toughened alumina ceramic powder according to claim 1, characterized in that, In step S5, the PH range is adjusted to 7-9, the PH adjusting agent includes nitric acid or ammonium hydroxide solution, and the concentration of the nitric acid or ammonium hydroxide solution is 0.1-0.4 mol / L.

8. The method for preparing zirconia-toughened alumina ceramic powder according to claim 1, characterized in that, In step S6, the mass ratio of the coated modified composite powder and deionized water is 0.5-2:1-15. Further, in step S6, the inlet temperature of the spray drying equipment is 180-250 DEG C, and the outlet temperature is 80-120 DEG C.

9. The method for preparing zirconia-toughened alumina ceramic powder according to claim 1, characterized in that, In step S7, the inert gas atmosphere includes a nitrogen atmosphere and / or an argon atmosphere, and the flow rate of the inert gas is 0.5-1.5 L / min. The high-temperature sintering has a temperature rising rate of 2-3 DEG C / min, a temperature of 1400-1600 DEG C, and a holding time of 2-4 h.

10. A zirconia toughened alumina ceramic powder, characterized by, Prepared by the method of any one of claims 1-9.

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