Method for improving low-temperature aging resistance of zirconia ceramic by utilizing defect engineering

Abstract

The invention relates to a method for improving low-temperature aging resistance of zirconia ceramic by utilizing defect engineering, which comprises the following steps: S1, preparation of zirconia slurry: taking zirconia powder with 3 mol% of yttrium oxide as a stabilizer as a raw material, and weighing the zirconia powder and deionized water according to a mass ratio of (1.5-2.5): 1; citric acid or acetic acid or nitric acid is dropwise added into deionized water, and the pH is adjusted to be 2.5-4; adding zirconium oxide powder into the adjusted aqueous solution step by step, and stirring to obtain zirconium oxide slurry; s2, introduction of powder intragranular defects: pouring the zirconium oxide slurry obtained in the step S1 into a sand mill, carrying out sanding treatment for 8-12 hours by adopting zirconium oxide microbeads as a medium, and introducing blade dislocation and lattice distortion crystal defects into zirconium oxide powder crystals; s3, after the powder containing the intragranular defects obtained in the step S2 is formed, pressureless sintering is conducted at the temperature of 1350-1425 DEG C in the air atmosphere, and the compact 3Y-TZP zirconia ceramic containing the intragranular defects is obtained. The phase transformation of the zirconia ceramic from a tetragonal phase to a monoclinic phase can be effectively inhibited, and the low-temperature aging resistance of the zirconia ceramic is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering ceramic materials, and more particularly to a method for improving the low-temperature aging resistance of zirconia ceramic by defect engineering. BACKGROUND

[0002] In recent years, dental implants have attracted more and more attention. Due to good bone integration, excellent biomechanical properties and white aesthetics, yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic is the only ceramic material suitable for dental implants. The high bending strength and toughness of zirconia are caused by the unique stress-induced tetragonal to monoclinic phase (t→m) transformation. This transformation is accompanied by an increase of about 4% in the unit cell, and generates local compressive stress around the transformed zirconia particles, thereby preventing further crack propagation. In addition to this beneficial effect, tetragonal to monoclinic phase transformation can also occur naturally in a humid environment, such as in the human body. Zirconia ceramic is subjected to unit cell expansion, which initiates microcracks leading to premature failure of zirconia implants, a phenomenon known as low-temperature aging, which endangers the long-term biological safety of zirconia implants.

[0003] Although the scientific mechanism of low-temperature aging of zirconia ceramic is not fully clear, a large number of studies have confirmed that the low-temperature aging of zirconia ceramic is nucleated and grown on the surface of zirconia ceramic through tetragonal to monoclinic phase (t→m) transformation in a humid environment. Humid environment is a necessary condition for low-temperature aging, so from the perspective of material preparation, zirconia ceramic first needs to be densified to be less than the invasion of water molecules. In addition, grain size control and chemical composition control are two means to improve the performance of zirconia ceramic. The reduction of zirconia ceramic grain size is beneficial to increase the surface energy of the system, the smaller the grain size, the more stable the tetragonal phase, and the better the low-temperature aging resistance. The yttria content in the tetragonal phase has a significant effect on the low-temperature aging resistance of zirconia ceramic: the higher the yttria content in the tetragonal phase, the more stable the tetragonal phase, and the better the low-temperature aging resistance of zirconia ceramic. In addition, the low-temperature aging resistance of zirconia ceramic can also be improved by additional addition of chemical components such as alumina, germania, etc. to adjust the sintering temperature, refine the grain size, and improve the low-temperature aging resistance of zirconia ceramic.

[0004] Although there are currently reports of using high-pressure discharge plasma sintering, discharge plasma sintering, hot-press sintering, oscillation sintering, hot isostatic pressing sintering and other pressure-assisted sintering methods to prepare 3Y-TZP ceramics with good low-temperature aging behavior, but zirconia products such as artificial dentures, artificial implants, artificial hip joints, etc. usually have responsible geometric size, and are more suitable for densification under air atmosphere by pressureless sintering. In addition, pressure-assisted sintering methods not only have expensive equipment and low production efficiency, but also use reducing atmosphere, which causes the color of the zirconia product to be black and gray, and cannot meet the aesthetic needs. At present, through the pressureless sintering preparation path, the densification sintering temperature of pure 3Y-TZP ceramic is 1450℃ or above. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a method for improving the low-temperature aging resistance of zirconia ceramics by defect engineering, which can effectively inhibit the phase transition of zirconia ceramics from tetragonal phase to monoclinic phase and improve the low-temperature aging resistance of zirconia ceramics.

[0006] The technical solution adopted by the present application to solve its technical problem is: a method for improving the low-temperature aging resistance of zirconia ceramics by defect engineering, comprising the following steps:

[0007] S1, zirconia slurry preparation: taking 3mol% yttrium oxide as a stabilizer, zirconia powder is used as raw material, and the zirconia powder and deionized water are weighed according to a mass ratio of 1.5-2.5:1; citric acid or acetic acid or nitric acid is added dropwise in the deionized water, and adjusted to pH=2.5-4; the zirconia powder is gradually added to the adjusted aqueous solution and stirred to obtain a zirconia slurry;

[0008] S2, introduction of intracrystalline defects of the powder: the zirconia slurry obtained in step S1 is poured into a sand mill, and zirconia microbeads are used as a medium for sand milling for 8-12h, so as to introduce edge dislocations and lattice distortion crystal defects into the interior of the zirconia powder crystals;

[0009] S3, after the powder containing intracrystalline defects obtained in step S2 is formed, pressureless sintering is carried out at 1300-1425℃ in an air atmosphere to obtain dense 3Y-TZP zirconia ceramics containing intracrystalline defects.

[0010] According to the above scheme, after the zirconia ceramic is accelerated to age in deionized water at 134℃ for 100h, the transformation of monoclinic phase in the zirconia ceramic is not higher than 3%.

[0011] According to the above scheme, the zirconia ceramic is a zirconia ceramic with 3mol% yttrium oxide as a stabilizer, and the zirconia ceramic does not contain aluminum oxide and germanium oxide.

[0012] According to the above scheme, the crystal structure of the zirconia ceramic is tetragonal or a mixed crystal of tetragonal and cubic.

[0013] According to the above scheme, the relative density of the zirconia ceramic is not less than 99%.

[0014] According to the above scheme, the sintering temperature in step S3 is 1350°C.

[0015] According to the above scheme, the sintering temperature in step S3 is 1400°C.

[0016] According to the above scheme, the sintering temperature in step S3 is 1425°C.

[0017] The method for improving the low-temperature aging resistance of zirconia ceramic by defect engineering according to the present application has the following beneficial effects:

[0018] Zirconia ceramic is a crystalline material, which is composed of atoms bonded by chemical bonds in a certain order. The essence of the low-temperature aging of zirconia ceramic is the crystal structure transition from tetragonal phase to monoclinic phase. This transition has been confirmed to be a martensitic phase transition, which is characterized by no thermal diffusion and involves simultaneous cooperative slip movement of atoms at a distance less than the atomic diameter. When the structural order of the crystalline material is destroyed, the energy barrier of the simultaneous cooperative movement of atoms will increase, and the difficulty of the simultaneous cooperative movement will also increase. Specifically for zirconia ceramic, introducing defects into the zirconia crystal will destroy the order of the zirconia crystal structure, making it difficult for atoms to undergo simultaneous cooperative movement, and thus making the crystal structure transition from tetragonal phase to monoclinic phase more difficult, thereby improving the low-temperature aging resistance of zirconia ceramic. The preparation method of the present application is simple, easy to operate, suitable for large-scale batch production, and can effectively improve the low-temperature aging resistance of zirconia ceramic. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present application will be further described below in conjunction with the drawings and examples, in which:

[0020] Figure 1 is the X-ray diffraction (XRD) pattern of the zirconia ceramic sintered at different temperatures according to the present application;

[0021] Figure 2 is the scanning electron microscope (SEM) photo of the sanding treated 3Y-TZP zirconia ceramic sintered at 1325-1450°C according to the present application;

[0022] Figure 3 is the high-resolution transmission electron microscope (HRTEM) photo of the zirconia powder raw material before sanding treatment according to the present application;

[0023] Figure 4This is a HRTEM photograph of the sand-milled zirconium oxide powder of the present invention;

[0024] Figure 5 This is a HRTEM image of the 3Y-TZP zirconia ceramic prepared at a sintering temperature of 1350° C. in Example 1 of the present invention;

[0025] Figure 6 This is a HRTEM photograph of the zirconia ceramic prepared at a sintering temperature of 1450° C. in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0026] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0027] like Figure 1 As shown, the method of the present invention for improving the low-temperature aging resistance of 3Y-TZP zirconia ceramics by defect engineering comprises the following steps:

[0028] (1) Preparation of zirconia slurry. Zirconia powder stabilized with 3 mol% yttrium oxide is used as the raw material. The raw material does not contain aluminum oxide or germanium oxide. The zirconia powder and deionized water are weighed in a mass ratio of 1.5 to 2.5:1. Citric acid, acetic acid, or nitric acid is added dropwise to the deionized water to adjust the pH to 2.5 to 4. The zirconia powder is gradually added to the adjusted aqueous solution and stirred to obtain a zirconia slurry.

[0029] Citric acid, acetic acid, or nitric acid acts as a slurry dispersant, and the choice can be flexibly adjusted based on the commercial zirconia powder. Zirconia powder and deionized water are weighed at a mass ratio of 1.5 to 2.5:1 to adjust the slurry dispersion: a low zirconia powder ratio results in a low slurry solids content, which facilitates dispersion but reduces production efficiency; a high zirconia powder ratio results in a high solids content, which hinders dispersion. The pH value is designed to achieve optimal dispersion; excessively high or low pH values ​​will reduce dispersion.

[0030] (2) Introducing defects into the powder crystals: The zirconium oxide slurry obtained in step (1) is sand-milled for 8 to 12 hours to introduce crystal defects into the zirconium oxide powder crystals.

[0031] The sand grinding process introduces crystal defects such as edge dislocations and lattice distortion into the zirconia powder through the extrusion and collision of the sand grinding medium and the zirconia powder.

[0032] (3) The zirconia powder with intracrystalline defects obtained in step (2) is densified by a conventional pressureless sintering process in an air atmosphere at a sintering temperature of 1350-1425°C, and through selection of a proper sintering temperature, a dense 3Y-TZP zirconia ceramic is obtained, and meanwhile, the crystal defects can be retained in the grains of the dense 3Y-TZP zirconia ceramic.

[0033] The conventional pressureless sintering process is as follows: first, the ceramic powder is formed in a mold, then the formed ceramic green body is subjected to cold isostatic pressing at a pressure of 200-250 MPa, and finally, the cold isostatic pressed ceramic green body is sintered in an air atmosphere without external auxiliary pressure.

[0034] (4) The obtained dense zirconia is subjected to an accelerated aging test to characterize its low-temperature aging resistance. The obtained 3Y-TZP zirconia ceramic is a zirconia ceramic with 3 mol% yttria as a stabilizer, and the crystal structure is tetragonal or a mixture of tetragonal and cubic; the relative density is not less than 99%. After the zirconia ceramic is subjected to accelerated aging in deionized water at 134°C for 100 h, the transformation of monoclinic phase in the zirconia ceramic is not higher than 3%.

[0035] The related test and detection methods involved in the present application are as follows:

[0036] The density (ρ 测 ) of the zirconia ceramic is determined by the Archimedes method;

[0037] The relative density R (%) of the zirconia ceramic is calculated as follows: R = ρ 测 / ρ 理 × 100%, wherein ρ 理 is the theoretical density of zirconia, and the value is 6.08 g / cm 3 ;

[0038] The average grain size of the zirconia ceramic is statistically determined based on a scanning electron microscope (SEM) photo by a screenshot method;

[0039] The phase crystal structure and composition in the zirconia ceramic are calculated by a Rietveld refinement method based on the results of an X-ray diffractometer (XRD) method;

[0040] The intracrystalline defects of the zirconia ceramic are observed by a high-resolution transmission electron microscope (HRTEM), and are quantitatively characterized by a statistical value of the density of edge dislocations based on the results of the HRTEM photo;

[0041] The statistical method of the density of edge dislocations in the grains of the zirconia ceramic (unit: m -2 ) is: the number of edge dislocations / field of view area;

[0042] The low-temperature aging of the zirconia ceramic is carried out by referring to ISO standard 13356:2015, specifically, the sintered zirconia sample is placed in a polytetrafluoroethylene tank containing deionized water, and then the sealed polytetrafluoroethylene tank is placed at 134 DEG C for 100 h of accelerated aging.

[0043] The low-temperature aging behavior of the zirconia ceramic is calculated based on the X-ray diffraction results of the sample after aging, and the calculation formula is: wherein X m is the monoclinic phase content after aging, I is the X-ray diffraction peak intensity of different crystal faces, and the numbers in the brackets are the Miller indices of the related crystal faces, and the monitoring is performed once every 25 h.

[0044] The sintering temperature regulation is the key of the present application. As described above, the sintered body density, the grain size, the yttria content in the tetragonal phase, and the intracrystalline defect density all affect the low-temperature aging resistance of the 3Y-TZP ceramic, and all of the four factors are closely related to the sintering temperature, and the four factors can be simultaneously regulated by changing the sintering temperature: the higher the sintering temperature, the larger the grain size, the lower the yttria content in the tetragonal phase, and the lower the intracrystalline defect density, which reduces the low-temperature aging resistance of the zirconia ceramic; if the sintering temperature is too low, the density of the zirconia ceramic is reduced, and the penetration of water molecules cannot be effectively resisted, which reduces the low-temperature aging resistance of the zirconia ceramic.

[0045] In the embodiments of the present application, the same zirconia powder is used as the initial raw material, a certain solid content is selected, an acid is used as the dispersant, and a pH value is selected for slurry preparation to illustrate the embodiments, and the purpose is to ensure the consistency of the comparative slurries.

[0046] In the embodiments of the present application, sand milling treatment is used as the introduction method of the intracrystalline defects of the powder. Other physical methods for introducing intracrystalline defects, such as high-energy ball milling, shock wave treatment, and similar physical methods, do not exceed the scope of the present application.

[0047] In the embodiments of the present application, the same sand milling time is used, and the purpose is to regulate the intracrystalline defect density of the 3Y-TZP ceramic by changing the sintering temperature under the condition of the same initial powder intracrystalline defect density, and then to compare the influence of different defect densities on the low-temperature aging performance of the 3Y-TZP ceramic.

[0048] In the comparative example 1 of the present application, the pure 3Y-TZP ceramic prepared from the zirconia powder without sand milling treatment is used.

[0049] In the comparative example 4 and the comparative example 5 of the present application, the 0.25wt% alumina doped 3Y-TZP ceramic is an excellent zirconia ceramic in terms of low-temperature aging resistance.

[0050] Example 1

[0051] The zirconia powder containing intracrystalline defects was sintered in air atmosphere by pressureless sintering process at a sintering temperature of 1350°C.

[0052] Example 2

[0053] The zirconia powder containing intracrystalline defects was sintered in air atmosphere by pressureless sintering process at a sintering temperature of 1400°C.

[0054] Example 3

[0055] The zirconia powder containing intracrystalline defects was sintered in air atmosphere by pressureless sintering process at a sintering temperature of 1425°C.

[0056] Comparative Example 1

[0057] The zirconia powder without sand milling treatment was sintered in air atmosphere by pressureless sintering process at a sintering temperature of 1470°C.

[0058] Comparative Example 2

[0059] The zirconia powder containing intracrystalline defects was sintered in air atmosphere by pressureless sintering process at a sintering temperature of 1325°C.

[0060] Comparative Example 3

[0061] The zirconia powder containing intracrystalline defects was sintered in air atmosphere by pressureless sintering process at a sintering temperature of 1450°C.

[0062] Comparative Example 4

[0063] A commercial zirconia powder with 0.25wt% alumina added was used as the starting material, and sintered in air atmosphere by pressureless sintering process at a sintering temperature of 1350°C.

[0064] Comparative Example 5

[0065] A commercial zirconia powder with 0.25wt% alumina added was used as the starting material, and sintered in air atmosphere by pressureless sintering process at a sintering temperature of 1400°C.

[0066] The sintered zirconia ceramics were characterized for low temperature aging performance and other properties.

[0067] As Figure 1XRD patterns of zirconia ceramics sintered at different temperatures, as shown in Figure 1, it can be seen that the crystal phase of the initial raw material powder of zirconia is a mixture of tetragonal phase and monoclinic phase; when the sintering temperature is 1000°C, the crystal phase of the zirconia ceramic no longer contains monoclinic phase; in the enlarged pattern of the right 72-76° region, when the sintering temperature is not lower than 1400°C, in addition to the tetragonal phase, the existence of the cubic phase is also detected in the zirconia ceramic. As shown in Figure 2, SEM photos of the sand-milling treated 3Y-TZP zirconia ceramic sintered at 1325-1450°C, the average grain size of the zirconia ceramic sintered at different temperatures is counted based on the SEM photos. Figure 2

[0068] Table 1

[0069]

[0070] As can be seen from Table 1, the properties of the 3Y-TZP zirconia ceramic prepared in Examples 1-3 and Comparative Examples 1-5 are counted. The pure 3Y-TZP ceramic in Comparative Example 1 which is not subjected to sand-milling treatment has a density of only 97.32% after sintering at 1470°C, and does not achieve complete densification; the sand-milling treated zirconia ceramic; when the sintering temperature is lower than 1325°C, the relative density of the sand-milling treated zirconia ceramic in Comparative Example 2 is lower than 99%. As described before, the low-temperature aging of the zirconia ceramic occurs in a humid environment, and the zirconia ceramic which is not dense is difficult to effectively resist the erosion of water vapor, therefore the samples obtained in Comparative Example 1 and Comparative Example 2 have relatively low density, and are not subjected to further low-temperature aging performance characterization.

[0071] Table 2

[0072]

[0073]

[0074] As shown in Table 2, the content of monoclinic phase in the 3Y-TZP zirconia ceramic prepared during the accelerated aging treatment at 134°C is counted. As can be seen from Table 2, the 3Y-TZP zirconia ceramic prepared in Example 1 exhibits the best low-temperature aging resistance, and no monoclinic phase is formed after 100h of accelerated aging experiment; in addition, within the sintering temperature range of 1350-1425°C, the grain size of the 3Y-TZP zirconia ceramic prepared in Examples 1-3 increases with the increase of the sintering temperature, but the conversion of the monoclinic phase of all the prepared 3Y-TZP zirconia ceramic after 100h of accelerated aging is not higher than 3%. However, when the sintering temperature reaches 1450°C, the content of the monoclinic phase of the sand-milling treated zirconia ceramic in Comparative Example 3 after 100h of accelerated aging is as high as 83%.

[0075] As shown in Figure 3, the SEM photos of the 3Y-TZP zirconia ceramic sintered at different temperatures, as shown in Figure 3, the grain size of the 3Y-TZP zirconia ceramic sintered at different temperatures is counted based on the SEM photos. Figure 3 ​As shown in the figure, the HRTEM image of the zirconia powder raw material before sand grinding is shown. It can be seen that the lattice fringes in the initial powder are continuous, parallel and regular, and almost no defects are observed. Figure 4 As shown in the HRTEM image of the powder after sand grinding, a large number of distortions and fractures can be seen in the lattice fringes, and a large number of dislocations can be observed (marked with the symbol “┴”), indicating that lattice defects have been successfully introduced into the raw powder crystals through sand grinding.

[0076] like Figure 5 As shown in the HRTEM image of the 3Y-TZP zirconia ceramic prepared at a sintering temperature of 1350°C in Example 1, it can be seen that a large number of edge dislocation defects are still retained inside the grains. Figure 6 As shown in the HRTEM image of the zirconia ceramic prepared at a sintering temperature of 1450°C in Comparative Example 3, it can be seen that the defects within the grains have completely disappeared. In the zirconia ceramic with 0.25w% alumina, the density of defects within the grains also decreases with increasing sintering temperature. This indicates that sintering temperature is a key factor in maintaining defects within the grains. This phenomenon can be explained by the fact that increasing sintering temperature increases the atomic diffusion rate. Since defects within the grains have higher energy, atomic diffusion always initiates at high-energy sites within the system. Therefore, the density of defects within the zirconia grains decreases with increasing sintering temperature.

[0077] As mentioned above, the refinement of grain size is beneficial to improving the low-temperature aging resistance of zirconia ceramics. The smaller the grain size, the better the low-temperature aging resistance. In order to further highlight the remarkable excellent effect of the present invention, the present invention selects samples with similar grain sizes for comparison of low-temperature aging behavior. As can be seen from Table 1, the average grain size of the zirconia ceramic in Example 2 is 206±43nm, which is slightly larger than the average grain size of the zirconia ceramic in Comparative Example 4, which is 195±42nm. The average grain size of the zirconia ceramic in Example 3 is 234±49nm, which is slightly larger than the average grain size of the zirconia ceramic in Comparative Example 5, which is 227±51nm. However, as can be seen from Table 2, the monoclinic phase of the 3Y-TZP zirconia ceramics prepared in Examples 2 and 3 after 100h accelerated aging is <1% and 3%, respectively, which is much lower than the 3Y-TZP zirconia ceramics prepared in Comparative Examples 4 (22%) and 5 (73%).

[0078] In addition to the effect of grain size, the existing researches show that the low-temperature aging resistance of zirconia ceramic is also affected by the content of yttria in the tetragonal phase of zirconia ceramic. The higher the content of yttria in the tetragonal phase, the better the low-temperature aging resistance of zirconia. Table 3 lists the content of yttria in the tetragonal phase of the zirconia ceramic prepared in the examples and comparative examples. It can be seen that the content of yttria in the tetragonal phase of the 3Y-TZP zirconia ceramic prepared in Example 2 and Example 3 is 2.3327 mol% and 2.2402 mol%, respectively, which is lower than that of the 3Y-TZP zirconia ceramic prepared in Comparative Example 4 (2.4466 mol%) and Comparative Example 5 (2.3489%).

[0079] It can be seen from the comparison of Example 2 and Comparative Example 4, Example 3 and Comparative Example 5 that the 3Y-TZP zirconia ceramic prepared in Examples 2 and 3 has a larger grain size, a lower content of yttria in the tetragonal phase, but exhibits better low-temperature aging resistance.

[0080] Table 3

[0081]

[0082]

[0083] Table 4 lists the density of the edge dislocations in the grains of the zirconia ceramic in Examples 2, 3 and Comparative Examples 4, 5. It can be seen that, compared with Examples 2 and 3, although the zirconia ceramic in Comparative Examples 4 and 5 has a smaller average grain size and a higher content of yttria in the tetragonal phase, the zirconia ceramic obtained in Examples 2 and 3 has a high defect density. As described above, the introduction of defects into the zirconia crystal will destroy the order of the structure of the zirconia crystal, making it difficult for atoms to move simultaneously and cooperatively, and thus making it more difficult for the tetragonal phase to transform into the monoclinic phase, thereby improving the low-temperature aging resistance of the zirconia ceramic. Therefore, the higher defect density is the fundamental reason why the 3Y-TZP ceramic prepared in Examples 2 and 3 exhibits better low-temperature aging resistance.

[0084] Table 4

[0085] Example Density of edge dislocations in the crystal grains (m -2 )]]> Example 2 5.12 x 10 16 ]] Example 3 3.34 x 10 16 ]] Comparative Example 4 2.78 x 10 16 ]] Comparative Example 5 0

[0086] The embodiments of the present application are described above with reference to the drawings, but the present application is not limited to the specific embodiments described above, which are merely illustrative and not restrictive. Those skilled in the art can make many modifications to the embodiments of the present application without departing from the spirit and scope of the present application and the claims, and these modifications are also within the scope of protection of the present application.

Claims

1. A method for improving the low-temperature aging resistance of zirconia ceramics by using defect engineering, characterized in that: The following steps are involved: S1. Preparation of zirconium oxide slurry: Using zirconium oxide powder stabilized with 3 mol% yttrium oxide as a raw material, weigh the zirconium oxide powder and deionized water in a mass ratio of 1.5 to 2.5:1; add citric acid, acetic acid, or nitric acid dropwise to the deionized water to adjust the pH to 2.5 to 4; gradually add the zirconium oxide powder to the adjusted aqueous solution and stir to obtain a zirconium oxide slurry; S2. Introducing defects into the powder crystals: Pour the zirconium oxide slurry obtained in step S1 into a sand mill, use zirconium oxide beads with a diameter of 0.1 to 0.3 mm as a medium, and sand mill for 8 to 12 hours to introduce edge dislocations and lattice distortion crystal defects into the zirconium oxide powder crystals; S3. After forming the powder containing intracrystalline defects obtained in step S2, pressureless sintering is performed at 1350-1425° C. in an air atmosphere to obtain dense 3Y-TZP zirconia ceramics containing intracrystalline defects.

2. The method for improving the low-temperature aging resistance of zirconia ceramics by using defect engineering according to claim 1, characterized in that: After the zirconia ceramic is subjected to accelerated aging in deionized water at 134° C. for 100 hours, the monoclinic phase content in the zirconia ceramic is not higher than 3%.

3. The method for improving the low-temperature aging resistance of zirconia ceramics by using defect engineering according to claim 1, characterized in that: The relative density of the zirconia ceramic is not less than 99%.

4. The method for improving the low-temperature aging resistance of zirconia ceramics by using defect engineering according to claim 1, characterized in that: The crystal structure of the zirconium oxide ceramic is a tetragonal crystal or a mixed crystal structure of tetragonal and cubic.

5. The method for improving the low-temperature aging resistance of zirconia ceramics by using defect engineering according to claim 1, characterized in that: The sintering temperature range in step S3 is 1350°C.

6. The method for improving the low-temperature aging resistance of zirconia ceramics by using defect engineering according to claim 1, characterized in that: The sintering temperature in step S3 is 1400°C.

7. The method for improving the low-temperature aging resistance of zirconia ceramics by using defect engineering according to claim 1, characterized in that: The sintering temperature in step S3 is 1425°C.

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