Preparation method and application of a strong and tough ZTA ceramic with a rod-like A2B2O7 pyrochlore structure

Abstract

The application discloses a preparation method and application of a rod-shaped A2B2O7 pyrochlore structure toughened ZTA ceramic and belongs to the technical field of zirconia toughened alumina. Raw material powders containing alumina, zirconia, an A element donor, a B element donor and a sintering aid are mixed, ball milled and sieved to obtain mixed powders; the mixed powders are granulated by adding water to obtain granulated powders; then, the granulated powders are pressed into a ceramic body which is heated and sintered, and after sintering, the ceramic body is cooled to room temperature to obtain the rod-shaped A2B2O7 pyrochlore structure toughened ZTA ceramic. According to the method, the rod-shaped pyrochlore structure phase A2B2O7 is generated in situ through the inducing effect of a specific sintering aid, so that the ZTA ceramic is toughened, the ZTA ceramic has high hardness and high fracture toughness at the same time, and can be widely applied to the fields of cutting tools, wear-resistant components and high-temperature structural parts.

Description

Technical Field

[0001] This invention relates to the field of zirconia-toughened alumina technology, specifically to a method for preparing and applying rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramics. Background Technology

[0002] Zirconia-toughened alumina (ZTA) ceramics are a class of structural ceramic materials that combine high strength, high hardness, and excellent wear resistance, and are widely used in cutting tools, seals, bearing balls, and medical implants. ZTA ceramics significantly improve fracture toughness by dispersing zirconia particles within an alumina matrix, achieving stress-induced phase transformation toughening and crack deflection mechanisms. However, zirconia particles are prone to coarsening and agglomeration during high-temperature sintering, limiting their phase transformation toughening effect; simultaneously, the interfacial bonding between alumina and zirconia is relatively weak, making it difficult to further improve the overall toughness and reliability of the ceramic.

[0003] To address these issues, researchers have attempted to regulate the microstructure of ZTA ceramics by introducing a second phase or sintering aids. For example, adding rare earth oxides can promote sintering densification and form stable grain boundary phases; introducing transition metal oxides (such as TiO2) can generate composite oxides during high-temperature sintering, thereby improving interfacial bonding strength; in addition, using co-precipitation to prepare precursor powders also helps improve particle dispersion and compositional uniformity. However, these methods generally suffer from limited toughening effects, insufficient phase stability, or complex preparation processes. Furthermore, the formed second phase is often equiaxed or randomly distributed, making it difficult to effectively deflect or bridge crack propagation, thus limiting further improvements in the toughness of ZTA ceramics.

[0004] The existing toughening mechanisms of ZTA ceramics still mainly rely on the phase transformation toughening of zirconia and the passivation effect of a small amount of second phase, resulting in limited room for overall toughness improvement. How to significantly improve the strength and toughness of materials by designing novel second-phase morphologies or constructing controllable microstructures, while ensuring high strength, has become a key technical problem urgently needing to be solved in this field. Summary of the Invention

[0005] To address the aforementioned limitations of existing technologies, the present invention aims to provide a method for preparing and applying rod-shaped A2B2O7 pyrochlore-structured, toughened ZTA ceramics. This method introduces Group A and Group B oxides (A being rare earth or alkali metal elements, and B being transition metal elements) capable of forming a pyrochlore structure. Under appropriate sintering conditions, rod-shaped (or needle-shaped) pyrochlore phases (A2B2O7) are generated in situ through the induction of specific sintering aids, forming a reinforcing phase network within the ZTA matrix. This pyrochlore phase possesses both excellent thermal stability and interfacial bonding, inducing crack deflection, bridging, and bifurcation during crack propagation, thereby achieving synergistic toughening through multiple mechanisms. Furthermore, the introduction of rare earth and alkaline earth oxide sintering aids into the system significantly improves densification and inhibits abnormal grain growth. This method is simple to prepare, widely applicable, and compatible with solid-state and co-precipitation methods. The resulting ceramic material exhibits high strength, high toughness, and excellent microstructural stability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a rod-shaped A2B2O7 pyrochlore structure-strengthened ZTA ceramic, comprising a rod-shaped A2B2O7 pyrochlore structure; the composition of the A2B2O7 pyrochlore structure is Y2Sn2O7 or Y2Ti2O7.

[0008] Furthermore, the rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic has a relative density of not less than 98.9%, a hardness of not less than 15.97 GPa, and a toughness of not less than 6.11 MPa·m. 1 / 2 .

[0009] A second aspect of the present invention provides a method for preparing the rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic, comprising the following steps:

[0010] (1) After mixing the raw material powder containing alumina, zirconium oxide, element A donor, element B donor and sintering aid, the mixture is ball-milled and sieved to obtain mixed powder; the element A donor is yttrium oxide, the element B donor is titanium oxide or tin oxide, and the sintering aid is lanthanum oxide and magnesium oxide.

[0011] (2) The mixed powder is granulated by adding water to obtain granulated powder;

[0012] (3) Press the granulated powder into a ceramic body;

[0013] (4) The ceramic blank is heated and sintered. After sintering, it is cooled to room temperature to obtain rod-shaped A2B2O7 pyrochlore structure toughened ZTA ceramic.

[0014] Sintering tools include, but are not limited to, muffle furnaces, tube furnaces, roller furnaces, and vacuum furnaces.

[0015] Furthermore, in step (1), the raw material powder is prepared by solid-phase method, co-precipitation method or sol-gel method.

[0016] Furthermore, in step (1), the mass ratio of alumina, zirconium oxide, element A donor, element B donor, and sintering aid is (81-90):(10-19):(0.1-1):(0.5-2):(0.1-1); the zirconium oxide is one or more of partially stabilized zirconium oxide, tetragonal zirconium oxide, monoclinic zirconium oxide, and fully stabilized zirconium oxide; the sieve used for ball milling is 100 mesh.

[0017] Furthermore, in step (2), the particle size of the granulation is 75±25 μm.

[0018] Furthermore, in step (3), the pressing molding method is any one of dry pressing, isostatic pressing, slurry molding, casting molding or hot pressing molding, and the pressure is 40-100MPa.

[0019] Furthermore, in step (4), during heating and sintering, the ceramic blank is heated to 1300-1650℃ at a rate of 1-100 ℃ / min and held for 1-7 hours.

[0020] The cooling process can be set to 1-100 ℃ / min, or it can cool naturally as the furnace cools.

[0021] A third aspect of the present invention provides the application of the preparation method described herein in the production of high-density, high-hardness, and high-toughness ceramics.

[0022] The preparation method provided by this invention is applicable not only to ZTA ceramics, but also to other oxide and carbide ceramics.

[0023] The rod-shaped A2B2O7 pyrochlore-reinforced ZTA ceramic prepared according to this invention contains rod-shaped A2B2O7 as a toughening phase. The in-situ generated rod-shaped A2B2O7 pyrochlore reinforcing phase is fundamentally different from the traditional toughening method that relies on externally added reinforcing particles. Externally added reinforcing phases are usually distributed independently in the matrix, and their toughening effect depends on the interfacial bonding effect after sintering, easily constrained by interfacial reactions, uneven agglomeration, and other problems. However, this invention, through the synergistic regulation of sintering aids, enables the A2B2O7 phase to precipitate in situ within the ZTA matrix and grow in a rod-shaped morphology, thus possessing significant structural and energy advantages. The in-situ grown rod-shaped A2B2O7 crystals have a naturally matched interfacial relationship with the surrounding particles, avoiding the common interfacial debonding or weak bonding problems of externally added particles. Their growth location is often at ZTA grain boundaries, particle contact areas, or stress concentration regions, forming a continuous or semi-continuous skeletal reinforcement network in the microstructure. These rod-shaped crystals can achieve multiple synergistic toughening effects: their high aspect ratio structure in the longitudinal direction is conducive to crack deflection, bifurcation, and passivation; the bridging structure across grain boundaries can significantly delay crack propagation; and they can absorb a large amount of fracture energy during pull-out or fracture processes. Furthermore, due to the synchronous densification with the matrix during in-situ crystal growth, their growth direction and distribution can play a role in local "microstructure regulation," making the grain boundary structure more stable and further improving the load transfer path and overall crack resistance. Compared with traditional external particle toughening, the in-situ generated rod-shaped A2B2O7 pyrochlore structure reinforcing phase has a stronger interfacial bond, more prominent morphological advantages, more uniform distribution, and more effective structural effect, which can significantly improve the fracture toughness of ZTA ceramics without sacrificing density and hardness, achieving efficient toughening. This invention, through the controllable induction of this in-situ rod-shaped toughening phase, achieves synergistic regulation of ZTA microstructure and mechanical properties, providing a new technical path for obtaining advanced structural ceramics with both high hardness and high toughness.

[0024] This invention employs a conventional preparation process route of ball milling, granulation, molding, debinding (which can be omitted), and high-temperature sintering. Under the synergistic effect of sintering aids, the A2B2O7 pyrochlore-structured reinforcing phase is induced to form in situ in the ZTA matrix and grow in a rod-like shape, thereby forming a tight bonding interface between the reinforcing phase and the matrix. This avoids problems such as easy agglomeration of the added reinforcing phase and weak interfacial bonding, ensuring the effective exertion of the reinforcing effect.

[0025] During high-temperature sintering, sintering aids can form a small amount of liquid phase or activate the grain boundary diffusion process, which not only benefits the densification of the ZTA matrix, but also significantly promotes the preferred growth and directional evolution of A2B2O7 pyrochlore structure crystals, enabling the rod-shaped reinforcing phase to form an interleaved reinforcing network structure in the matrix, thereby achieving a synergistic improvement in both strength and toughness.

[0026] Therefore, the rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic obtained by the preparation method provided by the present invention can significantly improve its fracture toughness while maintaining the original high hardness and high wear resistance of ZTA ceramic, thereby achieving a good balance between hardness and toughness, making the material have higher structural stability and longer service life, and suitable for harsh service environments such as cutting tools, wear-resistant components and high-temperature structural parts.

[0027] The beneficial effects of this invention are:

[0028] This invention achieves stable bonding and uniform distribution between the reinforcing phase and the matrix by in-situ inducing the formation of rod-shaped A2B2O7 pyrochlore reinforcing phase in the ZTA system, avoiding the problems of easy agglomeration and weak interfacial bonding of external reinforcing phases. The formed rod-shaped A2B2O7 pyrochlore reinforcing phase can generate multiple energy dissipation mechanisms such as crack deflection, bridging, and pull-out during load-bearing, thereby significantly improving the fracture toughness of ZTA ceramics without significantly sacrificing material hardness. This invention achieves in-situ controllable growth of the rod-shaped reinforcing phase through the synergistic regulation of sintering aids and A2B2O7 pyrochlore precursors, enabling stable strengthening and toughening effects within a wide range of formulations and process windows, with good process stability and high repeatability. The preparation process of this invention is based on conventional ceramic forming and sintering routes, does not rely on complex equipment, has strong raw material adaptability, and good process controllability, showing good prospects for industrial application.

[0029] This invention proposes a technical solution for in-situ construction of a rod-shaped A2B2O7 pyrochlore-structured reinforcing phase. Unlike traditional methods that rely solely on zirconia phase transformation toughening mechanisms or other second-phase toughening, this invention achieves stable generation of the rod-shaped second phase under conventional sintering conditions by adjusting experimental parameters. This method can be implemented without hot pressing or special atmosphere treatment, has a simple process flow, and possesses good feasibility and industrial application prospects. Attached Figure Description

[0030] Figure 1 The image shows the SEM morphology of the ZTA ceramic obtained in Example 1.

[0031] Figure 2 The image shows the EDS elemental distribution of the ZTA ceramic obtained in Example 1. Figure 2 Image 'a' in the figure represents the overall morphology of the test sample. Figure 2 In the middle, b is the total distribution spectrum. Figure 2 c represents the distribution of O elements. Figure 2 In the diagram, d represents the distribution of Al elements. Figure 2 In the diagram, e represents the distribution of Zr elements. Figure 2 f is the distribution map of element Y. Figure 2 In the diagram, g represents the distribution of La elements. Figure 2 In the diagram, h represents the distribution of Mg element. Figure 2 In the diagram, i represents the distribution of Ti elements.

[0032] Figure 3 The image shows the XRD pattern of the ZTA ceramic obtained in Example 1.

[0033] Figure 4 The image shows the SEM morphology of the ZTA ceramic obtained in Example 2.

[0034] Figure 5 The image shows the SEM morphology of the sintered and cooled product obtained in Comparative Example 1.

[0035] Figure 6 The image shows the SEM morphology of the sintered and cooled product obtained in Comparative Example 2. Detailed Implementation

[0036] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0037] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments.

[0038] This invention relates to a rod-shaped A2B2O7 pyrochlore structure-strengthened ZTA ceramic involving a multi-mechanism synergistic effect, primarily composed of a zirconia phase transformation toughening mechanism, the structural toughening effect of the rod-shaped A2B2O7 pyrochlore structure second phase, and the effect of stabilizer content regulation. Taking Y2Ti2O7 as an example, firstly, zirconia stabilized with Y2O3 is used as the toughening phase source. Under external load, tetragonal zirconia undergoes stress-induced phase transformation, resulting in volume expansion and the formation of a compressive stress field at the crack tip, thus achieving phase transformation toughening. Secondly, during sintering, TiO2 reacts with the Y component in a solid-state reaction, generating a rod-shaped A2B2O7 pyrochlore structure second phase in situ. This rod-shaped structure forms an oriented reinforcing phase in the matrix, which can change the crack path during crack propagation, producing crack deflection, bridging, or pinning effects, thus helping to increase crack propagation resistance. In addition, some Y component participates in the formation of the pyrochlore structure, correspondingly reducing the effective stabilizer content in the local zirconia. Changes in stabilizer content may affect the phase stability of tetragonal zirconia, making it more susceptible to phase transformation under external stress, thereby enhancing the toughening contribution of phase transformation to some extent.

[0039] The experimental materials used in the embodiments of this invention, unless otherwise specified, are all conventional experimental materials in the art and can be purchased through commercial channels. The raw materials used in this invention were purchased from Sinopharm Group. Among them, the CAS number of lanthanum oxide (La2O3) is 1312-81-8, and the zirconium oxide used was purchased from Shanghai MCC New Material Technology Co., Ltd. The product number of zirconium oxide 0Y without stabilizer (yttrium oxide) is ZY-ZrO2-6(0Y), and the structure is monoclinic phase (m-ZrO2); the product number of yttrium oxide stabilized zirconium oxide (3 mol.% Y2O3 stabilized ZrO2), i.e., 3YSZ, is ZY-ZrO2-6(3Y).

[0040] Example 1

[0041] Rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramics are prepared by the following steps:

[0042] Step 1: Using a mixture of 81g alumina and 19g zirconium oxide powder (3mol.% Y2O3 stabilized ZrO2) as the matrix, add 1g TiO2 powder, 0.4g La2O3 as a sintering aid, and 0.1g MgO as a sintering aid. Then, ball mill with water to obtain a mixed powder.

[0043] Step 2: Allow the mixed powder to dry naturally and pass it through a 100-mesh sieve; add 5g of PVA binder and 10g of water to the sieved mixed powder, mix well and granulate to obtain granulated powder with a particle size of 75±25 μm.

[0044] Step 3: Dry press the granulated powder under a pressure of 100MPa to obtain a ceramic green body.

[0045] Step 4: Heat the ceramic body at 600 ℃ for 2 hours to remove the adhesive.

[0046] Step 5: Place the debinding ceramic blank in a muffle furnace and heat it to 1550 ℃ at a rate of 2 ℃ / min, hold it for 2 h, and sintering is completed; then cool it down to room temperature with the furnace to obtain Y2Ti2O7 / ZTA ceramic as the product after sintering and cooling.

[0047] Example 2

[0048] Rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramics are prepared by the following steps:

[0049] Step 1: Preparing the powder using a co-precipitation method: 589g of aluminum nitrate, 49g of zirconium oxychloride, 3.6g of yttrium nitrate, 0.64g of magnesium nitrate, and 1.07g of lanthanum nitrate were dissolved in deionized water. The pH was then adjusted to 8 using ammonia water to obtain a precipitate. After drying, the precipitate was calcined at 1200°C for 2 hours to convert it into a mixed oxide. The mixed oxide contained 80g of aluminum oxide, 20g of zirconium oxide powder (3mol.% Y₂O₃ stabilized ZrO₂), 0.4g of La₂O₃ as a sintering aid, and 0.1g of MgO. Then, 1g of TiO₂ powder was added and ball-milled to obtain the mixed powder.

[0050] Step 2: Allow the mixed powder to dry naturally, pass it through a 100-mesh sieve, add 5g of PVA binder and 10g of water to the sieved mixed powder, mix well and granulate to obtain granulated powder with a particle size of 75±25 μm.

[0051] Step 3: Dry press the granulated powder under a pressure of 100MPa to obtain a ceramic green body;

[0052] Step 4: Hold the ceramic body at 600 ℃ for 2 hours to remove the adhesive;

[0053] Step 5: The ceramic green body after debinding is heated to 1550 ℃ in a muffle furnace at a rate of 2 ℃ / min and held for 2 h. After sintering is completed, it is cooled to room temperature in the furnace to obtain Y2Ti2O7 / ZTA ceramic as the product after sintering and cooling.

[0054] Example 3

[0055] A method for preparing rod-shaped A2B2O7 pyrochlore-structured and toughened ZTA ceramics, comprising the following steps:

[0056] Step 1: Using a mixed powder of 90g alumina and 10g zirconium oxide powder (3mol.% Y2O3 stabilized ZrO2) as the matrix, add 1g TiO2 powder, 0.4g La2O3 and 0.1g MgO sintering aid, and ball mill to obtain the mixed powder.

[0057] Step 2: Fill the dried and sieved mixed powder into the mold of the rapid hot press furnace.

[0058] Step 3: The ceramic blank is heated to 1500℃ at a rate of 100℃ / min under a pressure of 40MPa and held for 20min. After sintering, it is cooled to room temperature in the furnace to obtain ZTA ceramic.

[0059] Example 4

[0060] Rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramics are prepared by the following steps:

[0061] Step 1: Using a mixed powder of 80g alumina and 20g zirconium oxide powder (3mol.% Y2O3 stabilized ZrO2) as the matrix, add 1g SnO2 powder, 0.4g La2O3 and 0.1g MgO sintering aid, and ball mill to obtain the mixed powder.

[0062] Step 2: Mix the dried and sieved powder, 5g of PVA binder, and 10g of water together, and granulate to obtain granulated powder;

[0063] Step 3: Dry press the granulated powder under a pressure of 80 MPa to obtain a ceramic green body;

[0064] Step 4: Keep the ceramic body at 600 ℃ for 2 h to remove the adhesive;

[0065] Step 5: The ceramic green body is heated to 1550 ℃ in a muffle furnace at a rate of 10 ℃ / min and held for 2 h. After sintering is completed, it is cooled to room temperature in the furnace to obtain Y2Sn2O7 / ZTA ceramic.

[0066] Example 5

[0067] Rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramics are prepared by the following steps:

[0068] Step 1: Using a mixed powder of 80g alumina (123g aluminum hydroxide was prepared from 589g aluminum nitrate raw material via co-precipitation, and then calcined to obtain 80g alumina) and 20g zirconium oxide powder (3mol.% Y2O3 stabilized ZrO2) as the matrix, 1g TiO2 powder, 0.4g La2O3 and 0.1g MgO sintering aid were added, and the mixture was ball-milled to obtain the mixed powder.

[0069] Step 2: Mix the dried and sieved powder, 5g of PVA binder, and 10g of water together, and granulate to obtain granulated powder;

[0070] Step 3: Dry press the granulated powder under a pressure of 100MPa to obtain a ceramic green body;

[0071] Step 4: Keep the ceramic body at 600 ℃ for 2 h to remove the adhesive;

[0072] Step 5: The ceramic green body is heated to 1500 ℃ in a muffle furnace at a rate of 5 ℃ / min and held for 4 h. After sintering is completed, it is cooled to room temperature in the furnace to obtain Y2Ti2O7 / ZTA ceramic.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that TiO2 powder is not added to the raw materials. The specific steps are as follows:

[0075] Step 1: Using a mixture of 81g alumina and 19g zirconium oxide powder (3mol.% Y2O3 stabilized ZrO2) as the matrix, add a mixture of 0.4g La2O3 and 0.1g MgO as sintering aids, and then ball mill with water to obtain the mixed powder.

[0076] Step 2: Allow the mixed powder to dry naturally and pass it through a 100-mesh sieve; add 5g of PVA binder and 10g of water to the sieved mixed powder, mix well and granulate to obtain granulated powder with a particle size of 75±25 μm.

[0077] Step 3: Dry press the granulated powder under a pressure of 100MPa to obtain a ceramic green body.

[0078] Step 4: Heat the ceramic body at 600 ℃ for 2 hours to remove the adhesive.

[0079] Step 5: Place the debinding ceramic blank in a muffle furnace and heat it to 1550 ℃ at a rate of 2 ℃ / min, hold it for 2 h, and sintering is complete; then cool it down to room temperature with the furnace to obtain the sintered and cooled product.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 1 is that the raw materials do not contain Y2O3. The specific steps are as follows:

[0082] Step 1: Using a mixture of 81g alumina and 19g zirconia powder as the matrix, add 1g TiO2 powder, 0.4g La2O3 and 0.1g MgO as sintering aids, and ball mill with water to obtain a mixed powder.

[0083] Step 2: Allow the mixed powder to dry naturally and pass it through a 100-mesh sieve; add 5g of PVA binder and 10g of water to the sieved mixed powder, mix well and granulate to obtain granulated powder with a particle size of 75±25 μm.

[0084] Step 3: Dry press the granulated powder under a pressure of 100MPa to obtain a ceramic green body.

[0085] Step 4: Heat the ceramic body at 600 ℃ for 2 hours to remove the adhesive.

[0086] Step 5: Place the debinding ceramic blank in a muffle furnace and heat it to 1550 ℃ at a rate of 2 ℃ / min, hold it for 2 h, and sintering is complete; then cool it down to room temperature with the furnace to obtain the sintered and cooled product.

[0087] Comparative Example 3

[0088] The difference between this comparative example and Example 1 is that no sintering aids (La2O3 and MgO) are used in the raw materials. The specific steps are as follows:

[0089] Step 1: Using a mixture of 81g alumina and 19g zirconium oxide powder (3mol.% Y2O3 stabilized ZrO2) as the matrix, add 1g TiO2 powder and ball mill with water to obtain the mixed powder.

[0090] Step 2: Allow the mixed powder to dry naturally and pass it through a 100-mesh sieve; add 5g of PVA binder and 10g of water to the sieved mixed powder, mix well and granulate to obtain granulated powder with a particle size of 75±25 μm.

[0091] Step 3: Dry press the granulated powder under a pressure of 100MPa to obtain a ceramic green body.

[0092] Step 4: Heat the ceramic body at 600 ℃ for 2 hours to remove the adhesive.

[0093] Step 5: Place the debinding ceramic blank in a muffle furnace and heat it to 1550 ℃ at a rate of 2 ℃ / min, hold it for 2 h, and sintering is complete; then cool it down to room temperature with the furnace to obtain the sintered and cooled product.

[0094] Comparative Example 4

[0095] The difference between this comparative example and Example 1 is that TiO2 powder is not added to the raw materials, Y2O3 is not contained, and sintering aids (La2O3 and MgO) are not used.

[0096] Step 1: Using a mixture of 81g alumina and 19g zirconium oxide powder as a matrix, a mixed powder is obtained by ball milling with water.

[0097] Step 2: Allow the mixed powder to dry naturally and pass it through a 100-mesh sieve; add 5g of PVA binder and 10g of water to the sieved mixed powder, mix well and granulate to obtain granulated powder with a particle size of 75±25 μm.

[0098] Step 3: Dry press the granulated powder under a pressure of 100MPa to obtain a ceramic green body.

[0099] Step 4: Heat the ceramic body at 600 ℃ for 2 hours to remove the adhesive.

[0100] Step 5: Place the debinding ceramic blank in a muffle furnace and heat it to 1550 ℃ at a rate of 2 ℃ / min, hold it for 2 h, and sintering is complete; then cool it down to room temperature with the furnace to obtain the sintered and cooled product.

[0101] Test Example 1:

[0102] The sintered and cooled products obtained in Examples 1-2 and Comparative Examples 1-4 were subjected to performance tests. The performance test standards are as follows: relative density was determined by Archimedes' displacement method, hardness was determined by the standard "GB / T 16534-2009 Hardness Test Method for Fine Ceramics at Room Temperature", and toughness was determined by the standard ISO 21618:2019. The results are shown in Table 1.

[0103] Table 1 Performance Tests of Products After Sintering and Cooling

[0104]

[0105] According to Table 1, the products of Examples 1-2 all exhibit good relative density, hardness, and toughness, indicating that powder particles prepared by direct mixing or co-precipitation methods can be used to prepare the products. The toughness of the product in Example 1 is superior to that in Comparative Examples 1-4. SEM morphology analysis was performed on the Y2Ti2O7 / ZTA ceramics obtained in Examples 1-2, and the results are as follows: Figure 1 , Figure 4 As shown, gray alumina particles and white zirconium oxide particles are uniformly distributed, and white rod-shaped Y2Ti2O7 grains are also distributed; EDS elemental analysis of the ZTA ceramic obtained in Example 1 is shown in [reference needed]. Figure 2 XRD patterns can be found Figure 3 .

[0106] Based on the analysis of the ionic radius matching relationship, the reason for the formation of the A2B2O7 type pyrochlore structure in the products obtained in the examples is due to the presence of Y. 3+ With Ti 4+ The ratio of ionic radii is within the stable range of the pyrochlore structure. 3+ As the A-site ion has a relatively large radius, Ti 4+ As the B-site ion has a relatively small radius, the radius ratio between the two is approximately 1.49, which falls within the stable range of the cubic pyrochlore structure. This size matching relationship makes Ti... 4+ It can stably form B-site TiO6 octahedrons, Y 3+This occupies the A-site coordination environment and is conducive to the orderly arrangement of oxygen vacancies, thereby reducing the system's free energy and improving structural stability. Therefore, the Y–Ti–O system tends to form a stable Y2Ti2O7 pyrochlore phase under high-temperature conditions. From a formation mechanism perspective, under sintering conditions of 1550 ℃, the components within the system exhibit high diffusion activity, and the Y component readily undergoes a solid-state reaction with TiO2 at grain boundaries or local contact regions to form Y2Ti2O7. Furthermore, 1550 ℃ falls within the common formation temperature range of the A2B2O7 type pyrochlore phase, possessing the thermodynamic and kinetic conditions for forming a stable pyrochlore structure. Therefore, it is reasonable to identify the rod-shaped second phase as Y2Ti2O7, belonging to the A2B2O7 type pyrochlore structure. Similar conclusions are drawn for the Y2Sn2O7 ceramic formed in Example 4.

[0107] The Y2Ti2O7 / ZTA ceramic obtained in Comparative Example 1 was subjected to SEM morphology analysis, as shown below. Figure 5 As shown, without the Ti element provided by TiO2, Y2Ti2O7 is difficult to form. Without it, 1550 ℃ is insufficient to sinter the ceramic densely, resulting in a sharp decrease in mechanical properties and hardness.

[0108] The ZTA ceramics obtained in Comparative Example 2 were subjected to SEM morphology analysis, such as... Figure 6 As shown, compared to Example 1, without the introduction of Y2O3, the sample did not produce rod-shaped Y2Ti2O7, but mainly consisted of uniformly distributed alumina and zirconium oxide.

[0109] This invention simultaneously constructs a zirconia phase transformation toughening mechanism, a rod-shaped second-phase structure crack-inhibiting mechanism, and a stabilizer regulation mechanism within the same material system, achieving a synergistic effect of multiple toughening mechanisms to improve fracture toughness. Synergistic regulation is achieved through the design of a specific raw material system and its proportions. Taking ZTA-Y2Ti2O7 as an example, alumina is used as the matrix, and zirconia containing Y2O3 is added as a toughening phase source. Simultaneously, TiO2 is introduced as a reactant component. During high-temperature sintering, a solid-state reaction occurs in situ to generate the Y2Ti2O7 pyrochlore structure phase through the induction effect of sintering aids. On the other hand, MgO and La2O3, as sintering aids, participate in grain boundary regulation, promoting material densification while inducing grain growth behavior. The above components interact during sintering: on the one hand, TiO2 reacts with the Y component to form a stable rod-shaped pyrochlore phase; on the other hand, the sintering aids improve interfacial bonding, inhibit abnormal grain growth, and induce the formation of rod-shaped crystals, thereby achieving simultaneous optimization of second-phase generation, grain size regulation, and densification processes within the same sintering system. Therefore, the "synergistic effect" described in this invention is achieved through solid-state reaction and grain boundary regulation behavior involving Y2O3-stabilized zirconium oxide, TiO2 reaction components, and sintering aids, rather than the effect of a single component.

[0110] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A rod-shaped A2B2O7 pyrochlore-structured, toughened ZTA ceramic, characterized in that, It contains a rod-shaped A2B2O7 pyrochlore structure; the composition of the A2B2O7 pyrochlore structure is Y2Sn2O7 or Y2Ti2O7; The preparation method of rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramics includes the following steps: (1) After mixing the raw material powder containing alumina, zirconium oxide, element A donor, element B donor and sintering aid, the mixture is ball-milled and sieved to obtain mixed powder; the element A donor is yttrium oxide, the element B donor is titanium oxide or tin oxide, and the sintering aid is lanthanum oxide and magnesium oxide. (2) The mixed powder is granulated by adding water to obtain granulated powder; (3) Press the granulated powder into a ceramic body; (4) The ceramic blank is heated and sintered. After sintering, it is cooled to room temperature to obtain rod-shaped A2B2O7 pyrochlore structure toughened ZTA ceramic.

2. The rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic according to claim 1, characterized in that, The rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic has a relative density of not less than 98.9%, a hardness of not less than 15.97 GPa, and a toughness of not less than 6.11 MPa·m. 1 / 2 .

3. The rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic according to claim 1, characterized in that, In step (1), the raw material powder is prepared by solid-phase method, co-precipitation method or sol-gel method.

4. The rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic according to claim 1, characterized in that, In step (1), the mass ratio of alumina, zirconium oxide, element A donor, element B donor, and sintering aid is (81-90):(10-19):(0.1-1):(0.5-2):(0.1-1); the zirconium oxide is one or more of partially stabilized zirconium oxide, tetragonal zirconium oxide, monoclinic zirconium oxide, and fully stabilized zirconium oxide; the sieve used for ball milling is 100 mesh.

5. The rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic according to claim 1, characterized in that, In step (2), the particle size of the granulation is 75±25 μm.

6. The rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic according to claim 1, characterized in that, In step (3), the pressing molding method is any one of dry pressing, isostatic pressing, slurry molding, casting molding or hot pressing molding, and the pressure is 40-100MPa.

7. The rod-shaped A2B2O7 pyrochlore-structured toughened ZTA ceramic according to claim 1, characterized in that, In step (4), during heating and sintering, the ceramic blank is heated to 1300-1650℃ at a rate of 1-100 ℃ / min and held for 1-7 hours.

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