SPS-based yttrium tantalate ceramic ferroelastic domain width regulation and control method

Abstract

The invention discloses an SPS-based yttrium tantalate ceramic ferroelastic domain width regulation and control method, and mainly solves the problems of high cost, impurity phase introduction and poor precision of an existing regulation and control method. The preparation method comprises the following steps: 1) ball-milling and mixing high-purity Y2O3 and Ta2O5 to obtain turbid liquid; 2) drying the turbid liquid, grinding and sieving, and taking powder with the particle size of 100-200 meshes; (3) the powder is loaded into a graphite mold to be subjected to spark plasma sintering, and the desired ferroelastic domain width is controlled by regulating and controlling temperature parameters of an SPS system; and 4) after the sintering temperature reaches a preset final temperature, stopping heating, and after heat preservation, cooling to room temperature to obtain the YTaO4 ceramic block with the required domain width. According to the method, the ferroelastic domain width can be controlled in a single temperature parameter regulation and control mode, impurities are prevented from being introduced, the process is simple and easy to implement, and the method can be used for optimizing the microstructure of the YTaO4 ceramic material.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-performance ceramic materials, and further relates to a technology for controlling the width of ferroelastic domains. Specifically, it is a method for controlling the width of ferroelastic domains in yttrium tantalate ceramics based on spark plasma sintering (SPS), which can be used to optimize the microstructure of YTaO4 ceramic materials. Background Art

[0002] Ferroelastic domains are regions within a ferroelastic body where the spontaneous strain direction is consistent, and their width has a significant effect on the mechanical and electrical properties of the material. In recent years, yttrium tantalate (YTaO4) ceramics have attracted much attention in the fields of high-temperature structural materials, thermal barrier coatings (TBCs), and functional ceramics due to their excellent high-temperature stability, low thermal conductivity, and ferroelastic properties. The width of the domain directly affects the mechanical properties and high-temperature phase stability of the material. In order to regulate the width of the domain structure so that the material has better performance, domestic and foreign researchers have proposed the following schemes for regulating the domain structure: a) Chemical doping method: By doping ions (such as Sc) into the material system, the domain structure can be controlled. 3+ 、Nb 5+ 、Zr 4+ ) changes the lattice parameters and indirectly regulates the domain structure. For example, adding Zr to YTaO3 4+ , with Zr 4+ With increasing doping concentration, the monoclinic angle β and the magnetic domain rotation angle α decrease, respectively, lowering the ferroelastic domain reversal energy barrier. b) External field induction method: Domain structure is regulated through external stress, electric field, magnetic field, etc. For example, bending deformation can flip and control the domain boundary polarization of SrTiO3, producing ferroelectric-like hysteresis loop behavior; directional grain growth can be induced through temperature gradient fields and external electric fields.

[0003] By regulating the width of ferroelastic domains, the microstructure of ceramic materials can be optimized, enabling them to more effectively disperse stress across domain boundaries when subjected to external forces, thereby improving the material's toughness and crack resistance. Furthermore, a reasonable distribution of domain widths can enhance the fatigue resistance of ceramics, resulting in improved stability under repeated loading conditions. This optimization of mechanical properties holds great potential for ferroelastic ceramics in the field of high-performance ceramic materials, particularly in applications requiring high toughness and fatigue resistance.

[0004] However, chemical doping introduces impurities that reduce material purity, and the doped ions tend to segregate, resulting in a discrete domain width distribution. The external field induction method requires specialized equipment, is costly, and cannot be mass-produced. Furthermore, stress loading can easily induce microcracks. Furthermore, both methods suffer from low control precision. Summary of the Invention

[0005] The present invention aims to address the shortcomings of the prior art by proposing a method for controlling the ferroelastic domain width of yttrium tantalate ceramics using spark plasma sintering (SPS). This method primarily addresses the high cost, introduction of impurities, and poor precision of existing control methods. By directly controlling the grain growth rate and domain wall pinning effect of the yttrium tantalate ceramic through single-parameter manipulation of the spark plasma sintering (SPS) temperature, the present invention establishes a linear relationship between temperature and ferroelastic domain width. This method achieves precise control of domain width without chemical doping, shortening the process cycle, and reducing energy consumption.

[0006] To achieve the above objectives, the technical solutions of the present invention include the following:

[0007] (1) High-purity Y2O3 and Ta2O5 were added to anhydrous ethanol in a molar ratio of 1:1 and ball-milled to obtain a suspension;

[0008] (2) drying the suspension obtained in step (1) in an oven, then grinding and sieving to obtain a powder with a particle size between 100 and 200 meshes;

[0009] (3) The powder obtained in step (2) is loaded into a graphite mold and placed in a spark plasma sintering (SPS) system, and the relevant parameters of the SPS system are set, including vacuum degree, axial pressure and heating rate, and the final temperature is set to any temperature value within the range of 1350° C. to 1600° C., and spark plasma sintering is performed;

[0010] (4) After the sintering temperature reaches the final temperature, stop heating, keep the temperature at the final temperature, and then cool to room temperature;

[0011] (5) The ceramic block obtained in step (4) is taken out to obtain YTaO4 ceramic blocks with different domain widths.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] First, since the present invention controls the domain width only through a single temperature parameter and does not require doping or post-processing, the process operation is simple and easy to implement, which can effectively shorten the process cycle and reduce energy consumption.

[0014] Second, the present invention regulates the temperature parameters so that the width of the ferroelastic domain changes linearly with temperature. Compared with the traditional chemical doping method, there is no situation where the material purity is reduced due to the introduction of impurity phases. In addition, the traditional regulation method is prone to segregation of doped ions. The single temperature parameter regulation method proposed in the present invention can avoid the introduction of impurities and does not cause the domain width distribution to be discrete.

[0015] Third, the domain width control method proposed in the present invention can effectively achieve precise control of domain width in the range of 0.02μm-0.43μm, has industrial potential and is repeatable, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart for realizing the method of the present invention;

[0017] Figure 2 is a scanning electron microscope image of a YTaO4 ceramic block at different sintering temperatures in the present invention;

[0018] Figure 3 This is a statistical diagram of the domain structure width of the YTaO4 ceramic block at different sintering temperatures in the present invention;

[0019] Figure 4 This is a curve diagram showing the relationship between the domain width of the YTaO4 ceramic block in the present invention and the sintering temperature of the SPS system. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] Example 1: Refer to the attached Figure 1 and 4 The present invention proposes a method for controlling the width of ferroelastic domains of yttrium tantalate ceramics based on SPS, which specifically includes the following steps:

[0022] Step 1) High-purity Y2O3 and Ta2O5 (i.e., purity ≥99.99%) are added to anhydrous ethanol in a molar ratio of 1:1 and ball-milled for at least 12 hours to obtain a suspension;

[0023] Step 2) drying the suspension obtained in step 1) in an oven, then grinding and sieving to obtain a powder with a particle size between 100 and 200 meshes; in this embodiment, the suspension is preferably placed in an oven at 80° C. for 12 hours to achieve drying;

[0024] Step 3) The powder obtained in step 2) is put into a graphite mold and placed in a spark plasma sintering (SPS) system. The parameters of the SPS system are set, including vacuum, axial pressure and heating rate. In this embodiment, the vacuum is preferably set to ≤10 -3 Pa, applying an axial pressure of 40-70 MPa and a heating rate of 50°C / min; setting the final temperature to any temperature value within the range of 1350°C to 1600°C for spark plasma sintering;

[0025] Step 4) After the sintering temperature reaches the final temperature, the temperature is stopped and kept at the final temperature. In this embodiment, the holding time is set to 10-60 minutes, preferably 10 minutes, and then the temperature is reduced to room temperature at 50-100°C / min;

[0026] Step 5) The ceramic block obtained in step 4) is taken out to obtain YTaO4 ceramic blocks with different domain widths; the domain width of the ceramic block is in the range of 0.02μm--0.43μm, and the specific width value is linearly related to the sintering temperature change of the SPS system, such as Figure 4 As shown; specifically: the domain width of the YTaO4 ceramic block increases with increasing temperature, that is, the higher the temperature, the wider the average width of the ferroelastic domain of the obtained ceramic block; when the final temperature is set to 1350℃, the corresponding YTaO4 ceramic block with an average domain width of 0.02μm is obtained; when the final temperature is set to 1600℃, the corresponding YTaO4 ceramic block with an average domain width of 0.43μm is obtained.

[0027] Example 2: The overall implementation steps of the ferroelastic domain width control method proposed in this example are the same as those in Example 1. Figure 1-4 The average width of the ferroelastic domain of the YTaO4 ceramic block is controlled to be 0.15 μm. The parameter settings are given and the implementation process of the present invention is further described in detail with a specific example:

[0028] Step 1: Add high-purity Y2O3 and Ta2O5 in a molar ratio of 1:1 to anhydrous ethanol and perform ball milling for 15 hours to obtain a suspension;

[0029] Step 2: drying the suspension obtained in step 1) in an oven, then grinding and sieving to obtain a powder with a particle size between 100 and 200 meshes; in this embodiment, the suspension is preferably placed in an oven at 80° C. for 12 hours to achieve drying;

[0030] Step 3: The powder obtained in step 2 is loaded into a graphite mold and placed in a spark plasma sintering (SPS) system. The parameters of the SPS system are set, including vacuum, axial pressure, and heating rate. In this embodiment, the vacuum is preferably set to ≤10 -3 Pa, applied axial pressure of 50 MPa, heating rate of 50 ° C / min; set the final temperature to 1400 ° C for spark plasma sintering;

[0031] Step 4: After the sintering temperature reaches the final temperature, stop heating and keep it at the final temperature for 15 minutes, then cool it down to room temperature at 60℃ / min;

[0032] Step 5: Take out the ceramic block obtained in step 4 to obtain a YTaO4 ceramic block with an average domain width of 0.15 μm.

[0033] Example 3: The overall implementation steps of the ferroelastic domain width control method proposed in this example are the same as those in Example 1. Figure 1-4 The average width of the ferroelastic domain of the YTaO4 ceramic block is controlled to be 0.27 μm. The parameter settings are given and the implementation process of the present invention is further described in detail with a specific example:

[0034] Step A: High-purity Y2O3 and Ta2O5 were added to anhydrous ethanol in a molar ratio of 1:1 and ball-milled for 20 hours to obtain a suspension;

[0035] Step B: drying the suspension obtained in step 1) in an oven, then grinding and sieving to obtain a powder with a particle size between 100 and 200 meshes; in this embodiment, the suspension is preferably placed in an oven at 80° C. for 12 hours to achieve drying;

[0036] Step C: The powder obtained in step B is loaded into a graphite mold and placed in a spark plasma sintering (SPS) system. The relevant parameters of the SPS system are set, including vacuum degree, axial pressure and heating rate. In this embodiment, the vacuum degree is preferably set to ≤10 -3 Pa, applied axial pressure of 70 MPa, heating rate of 50 ° C / min; set the final temperature to 1550 ° C for spark plasma sintering;

[0037] Step D: After the sintering temperature reaches the final temperature, the temperature is stopped and kept at the final temperature for 15 minutes, and then the temperature is reduced to room temperature at a rate of 100°C / min;

[0038] Step E: Take out the ceramic block obtained in step D to obtain a YTaO4 ceramic block with an average domain width of 0.27 μm.

[0039] Figure 2 These are scanning electron microscope images of YTaO4 ceramic blocks at different sintering temperatures of the present invention. From the first figure, it can be seen that when the sintering temperature is 1350°C, the obtained ceramic block is incompletely sintered, the ferroelastic domain content is very small, and the width is narrow; from the second figure, it can be seen that when the sintering temperature is 1400°C, the sintering of the obtained ceramic block is basically completed, the ferroelastic domain content increases, but the width is uneven, and the content of narrow domains is relatively high; from the third figure, it can be seen that when the sintering temperature is 1550°C, the sintering of the obtained ceramic block is complete, the ferroelastic domains are evenly distributed, and the width is also relatively uniform; from the fourth figure, it can be seen that when the sintering temperature is 1600°C, the obtained ceramic block is completely sintered, the ferroelastic domains are evenly distributed, the width is uniform, and the width is larger than the ferroelastic domains obtained at 1550°C.

[0040] Figure 3 This is a statistical diagram of the domain width of ceramic blocks at different sintering temperatures of the present invention. It can be seen that the average domain width corresponding to the sintering temperature of 1350°C is 0.02μm, the average domain width corresponding to the sintering temperature of 1400°C is 0.15μm, the average domain width corresponding to the sintering temperature of 1550°C is 0.27μm, and the average domain width corresponding to the sintering temperature of 1600°C is 0.43μm. It can be seen that with the increase of the sintering temperature, the ferroelastic domain not only increases in width, but also the width distribution becomes uniform.

[0041] The present invention can effectively control the formation and evolution process of ferroelastic domains in yttrium tantalate ceramics by precisely controlling the spark plasma sintering temperature, thereby achieving precise control of the ferroelastic domain width. By regulating the ferroelastic domain width, the microstructure of the ceramic material can be optimized so that when it is subjected to external forces, the domain boundaries can more effectively disperse stress, thereby improving the toughness and crack resistance of the material. In addition, a reasonable domain width distribution can also enhance the fatigue resistance of the ceramic, so that it exhibits better stability under repeated loading conditions. This optimization of mechanical properties enables ferroelastic ceramics to show great application potential in the field of high-performance ceramic materials, especially in applications requiring high toughness and high fatigue resistance. For ferroelastic ceramic materials, regulating the domain width can significantly improve their electrical properties. By controlling the size and distribution of the domains, the coercive field of the ceramic can be effectively reduced, and its dielectric and piezoelectric properties can be improved, thereby improving the comprehensive performance of the ceramic material in practical applications.

[0042] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It is apparent that, after understanding the content and principles of the present invention, those skilled in the art may make various modifications and alterations in form and detail without departing from the principles and structure of the present invention. However, such modifications and alterations based on the concepts of the present invention remain within the scope of protection of the claims of the present invention. Furthermore, portions of the present invention not described in detail are common knowledge among those skilled in the art.

Claims

1. A method for controlling the width of ferroelastic domains in yttrium tantalate ceramics based on SPS, characterized in that: The steps include: (1) High-purity Y2O3 and Ta2O5 were added to anhydrous ethanol in a molar ratio of 1:1 and ball-milled to obtain a suspension; (2) drying the suspension obtained in step (1) in an oven, then grinding and sieving to obtain a powder with a particle size between 100 and 200 meshes; (3) The powder obtained in step (2) is loaded into a graphite mold and placed in a spark plasma sintering (SPS) system, and the relevant parameters of the SPS system are set, including vacuum degree, axial pressure and heating rate, and the final temperature is set to any temperature value within the range of 1350° C. to 1600° C., and spark plasma sintering is performed; (4) After the sintering temperature reaches the final temperature, stop heating, keep the temperature at the final temperature, and then cool to room temperature; (5) The ceramic block obtained in step (4) is taken out to obtain YTaO4 ceramic blocks with different domain widths.

2. The method according to claim 1, wherein: The high-purity Y2O3 and Ta2O5 in step (1) refer to Y2O3 with a purity of ≥99.99% and Ta2O5 with a purity of ≥99.99%.

3. The method according to claim 1, wherein: The ball milling mixing time in step (1) is not less than 12 hours.

4. The method according to claim 1, wherein: The step (2) is to use an oven to dry the suspension obtained in the step (1), specifically by placing the suspension in an oven at 80° C. for 12 hours.

5. The method according to claim 1, wherein: The SPS system parameters in step (3) include vacuum degree ≤ 10 -3 Pa, the applied axial pressure is 40-70 MPa, and the heating rate is 50°C / min.

6. The method according to claim 1, wherein: The insulation time in step (4) is 10-60 minutes.

7. The method according to claim 1, wherein: The step (4) of cooling to room temperature is to cool to room temperature at a rate of 50-100°C / min after the insulation time is over.

8. The method according to claim 1, wherein: The domain width of the YTaO4 ceramic block in step (5) is in the range of 0.02 μm to 0.43 μm, and is linearly related to the sintering temperature change of the SPS system.

9. The method according to claim 8, characterized in that: The domain width of the YTaO4 ceramic block shows a linear relationship with the sintering temperature change of the SPS system. Specifically, the domain width of the YTaO4 ceramic block increases with increasing temperature, that is, the higher the temperature, the wider the average width of the ferroelastic domain of the obtained ceramic block; when the final temperature is set to 1350°C, the corresponding YTaO4 ceramic block has an average domain width of 0.02μm; when the final temperature is set to 1600°C, the corresponding YTaO4 ceramic block has an average domain width of 0.43μm.

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