GdZrO-based ceramics and ultrafast sintering method based on non-stoichiometric control

Abstract

The application discloses a gadolinium zirconate ceramic based on non-stoichiometric ratio regulation and an ultrafast sintering method, and has a chemical formula of Gd 2‑ x Zr 2+x O 7+x / 2 , wherein 0.5 >= x >= -0.5, and x is not equal to 0; the gadolinium zirconate ceramic has a single fluorite phase structure; and the microstructure of the gadolinium zirconate ceramic has no obvious holes, and the growth degree of crystal grains increases with the increase of the deviation degree of the stoichiometric ratio. The gadolinium zirconate ceramic based on the non-stoichiometric ratio regulation is prepared by using the ultrafast sintering method; the ceramic is prepared by performing ball milling, granulation, tabletting and glue removal treatment on mixed powders of Gd2O3 and ZrO2, and then performing ultrafast sintering at a temperature increasing rate of 500-1000 DEG C / s and a sintering time of less than 180 s. The application introduces structural defect states by deviating the ratio of Gd and Zr, and cooperates with the diffusion / activation behavior under the induction of a strong external heat field formed by the ultrafast sintering to realize performance optimization.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ceramic material preparation, in particular to a high-temperature structural material gadolinium zirconate ceramic, and more particularly to a gadolinium zirconate ceramic based on non-stoichiometric ratio regulation and an ultrafast sintering method. BACKGROUND

[0002] With the increasing demand for high-temperature structural materials and functional materials, rare earth zirconate ceramics have shown great potential for application in aerospace, nuclear energy and high-temperature protection due to their excellent thermodynamic stability, high melting point, low thermal conductivity and good corrosion resistance. These materials not only maintain excellent physical and chemical properties in extreme environments, but also have good designability to meet the special needs of different application scenarios. Among the family of rare earth zirconate ceramics, gadolinium zirconate (Gd2Zr2O7) ceramic has become a research hotspot due to its low sintering temperature and adjustable thermal expansion coefficient.

[0003] Traditional ceramic sintering methods, such as conventional sintering and hot-press sintering, usually require long-time high-temperature treatment to promote the densification between ceramic particles. However, these methods have significant limitations. First, the high temperature and long-time sintering process results in high energy consumption, which does not meet the current industry trend of energy saving and emission reduction. Second, long-time high-temperature treatment easily causes grain coarsening, which significantly reduces the mechanical properties and functional characteristics of the material. In addition, traditional sintering methods are difficult to achieve precise control of the microstructure, limiting the further improvement of the performance of ceramic materials.

[0004] In recent years, ultrafast sintering technology has attracted widespread attention as a new ceramic preparation method, with the advantages of significantly shortening the sintering time and reducing energy consumption. Compared with traditional sintering technology, ultrafast sintering can complete the densification process of ceramics in a few minutes or even seconds, greatly improving production efficiency. The core of this technology is to induce rapid diffusion and sintering on the surface of ceramic particles through rapid heating and precise temperature control.

[0005] Non-stoichiometric ratio regulation is a method of optimizing the performance of a material by changing its composition ratio. The present application attempts to adjust the ratio of Gd to Zr in gadolinium zirconate ceramic to explore its influence on the crystal structure, phase composition and sintering behavior. For example, materials deviating from stoichiometric ratio may form additional defects or second phases, thereby changing the diffusion mechanism and densification path of the material. In addition, non-stoichiometric ratio regulation may also optimize the thermal expansion coefficient, thermal conductivity and thermal shock resistance of the ceramic, providing more possibilities for its application in high-temperature complex environments. SUMMARY

[0006] The present application aims to overcome the deficiencies of long sintering cycle, high energy consumption, low density and single performance control means in the existing gadolinium zirconate ceramic preparation technology, and proposes a gadolinium zirconate ceramic with a non-stoichiometric composition design, and the non-stoichiometric gadolinium zirconate ceramic material is prepared by a method based on ultrafast ceramic sintering. The material has the characteristics of dense structure, controllable defects and excellent performance, and can be applied to high-temperature structural materials, thermal barrier coatings, solid electrolytes, nuclear waste coating and other frontier application fields.

[0007] To achieve the above-mentioned application purposes, the present application adopts the following technical solutions.

[0008] The present application first provides a gadolinium zirconate ceramic based on non-stoichiometric regulation, and the chemical formula of the gadolinium zirconate ceramic is Gd 2-x Zr 2+x O 7+x / 2 , wherein 0.5≥x≥-0.5, and x≠0.

[0009] Further, the gadolinium zirconate ceramic based on non-stoichiometric regulation has a single fluorite structure.

[0010] Further, compared with the gadolinium zirconate ceramic Gd2Zr2O7 satisfying the stoichiometric ratio, the XRD pattern peak position of the gadolinium zirconate ceramic based on non-stoichiometric regulation is shifted; by deviating the ratio of Gd and Zr, the gadolinium zirconate ceramic based on non-stoichiometric regulation introduces crystal structure defect states.

[0011] Further, the gadolinium zirconate ceramic based on non-stoichiometric regulation has high density and no obvious pores; the grain is small and uniform, and the average grain size is 2.7~7.8μm, and as the deviation degree of the stoichiometric ratio increases, the grain growth degree becomes larger.

[0012] Compared with the traditional gadolinium zirconate ceramic Gd2Zr2O7 satisfying the stoichiometric ratio, the present application adopts a novel composition design, introduces structural defect states by deviating the ratio of Gd and Zr, and realizes performance optimization. The present application obtains a gadolinium zirconate ceramic with a unique crystal structure, for example, the gadolinium zirconate ceramic prepared in each embodiment of the present application has lattice constant changes, peak position shifts and different crystal structure parameters in XRD characterization, which are different from the traditional Gd2Zr2O7 ceramic. Due to the non-stoichiometric gadolinium zirconate ceramic material, by controlling the deviation degree of A / B site cations, i.e. Gd and Zr ions, a large number of adjustable anti-site defects and oxygen vacancies are introduced, which effectively widens the structural regulation dimension of the material and enhances the ion migration performance, thermal stability and corrosion resistance of the material. By adjusting the deviation degree of Gd 2-x Zr 2+x O 7+x / 2The middle x value obtains the gadolinium zirconate ceramic material system with different lattice parameters, defect state density and microstructure, which provides a new way for structure-performance regulation.

[0013] Secondly, the application also provides a kind of above-mentioned non-stoichiometric gadolinium zirconate ceramic ultrafast sintering technology, which has the characteristics of very short sintering time (usually ≤5 minutes), can effectively promote the densification of ceramic material and inhibit grain coarsening, etc., and reduce energy consumption and improve efficiency. The non-stoichiometric ceramic prepared by the method has the advantages of uniform structure, controllable microdefects and no obvious pores. The non-stoichiometric gadolinium zirconate ceramic prepared by the ultrafast sintering technology has the following characteristics: (1) fast and energy-saving sintering process: break through the technical bottleneck of traditional high temperature and long time sintering, significantly reduce energy consumption and cost; (2) the prepared ceramic material has excellent microstructure, such as the non-stoichiometric gadolinium zirconate ceramic prepared in each embodiment shows the characteristics of small and uniform grain size and high density. The non-stoichiometric gadolinium zirconate ceramic material and its ultrafast sintering preparation method provided by the application can provide a new functional ceramic solution for related fields.

[0014] Specifically, the ultrafast sintering method of the non-stoichiometric gadolinium zirconate ceramic provided by the application comprises the following steps:

[0015] Step one, according to the chemical formula Gd 2-x Zr 2+x O 7+x / 2 (0.5≥x≥-0.5, and x≠0) of the stoichiometric proportion of Gd2O3 and ZrO2 mixed powder.

[0016] Step two, the mixed powder is ball milled in a planetary ball mill, and the obtained slurry is dried in an oven after ball milling.

[0017] Step three, the dried powder is hand ground, and then powder granulation treatment is carried out.

[0018] Step four, the granulated powder is put into a tablet press mold, the tablet press mold is put on a tablet press for pressing and pressure holding for a period of time, and the pressed body is put into a muffle furnace for degassing treatment.

[0019] Step five: the degassed body is put into an ultrafast sintering furnace for ultrafast sintering. The non-stoichiometric gadolinium zirconate ceramic based on the non-stoichiometric ratio is prepared.

[0020] Preferably, in step one, the particle size of the Gd2O3 and ZrO2 powders is 500 nm-1500 nm.

[0021] Preferably, in step two, the rotation speed of the ball mill is 300-500 r / min, and the ball milling time is 8-12 h.

[0022] Preferably, in step two, the temperature of the oven is 90-100℃, and the drying time is 8-12 h.

[0023] Preferably, in step three, the manual grinding time is 5-10 min.

[0024] Preferably, in step three, 3-10% PVA is added during granulation.

[0025] Preferably, in step four, the pressure is 200-400 MPa, and the pressure time is 2-5 min.

[0026] Preferably, in step four, the temperature during the glue removal is 500-650℃, and the glue removal time is 4-6 h.

[0027] Preferably, in step five, the heating rate of the ultrafast sintering furnace is 500-1000℃ / s. The sintering temperature is 1600-1650℃. The sintering time is 60-180 s, and the sample is naturally cooled after sintering.

[0028] The gadolinium zirconate ceramic based on non-stoichiometric ratio control and the ultrafast sintering method have the following advantages:

[0029] (1) The gadolinium zirconate ceramic composition ratio of the application adopts a non-stoichiometric ratio method. When the composition deviates from the stoichiometric ratio, additional interstitial or vacancy defects are generated in the sample, which can significantly reduce the thermal conductivity.

[0030] (2) The synthesized ceramic has a single fluorite structure and excellent thermophysical properties.

[0031] (3) The application uses an ultrafast sintering method to prepare the material, and the heating rate is much higher than that of the conventional sintering method, which greatly improves the preparation efficiency.

[0032] (4) The ceramic is prepared without adding any sintering aid, and single phase is achieved, and formation of the second phase is effectively controlled. In addition, the defect regulation mechanism caused by the non-stoichiometric structure design and the diffusion / activation behavior under the induction of the strong thermal field play a synergistic role in the present application, which significantly reduces the energy barrier of the ceramic phase formation, strengthens the ion migration rate, and realizes rapid crystallization and uniform single phase formation in a very short time. The exploration of the present application proves that by regulating the non-stoichiometric ratio of gadolinium zirconate ceramic, not only the sintering behavior can be optimized, but also the mechanical properties and functional characteristics can be significantly improved, thereby providing a new technical approach for efficient and low-cost ceramic preparation.

[0033] (5) By changing the stoichiometric ratio, the grain size of the final gadolinium zirconate sample can be regulated.

[0034] (6) The preparation method of the gadolinium zirconate ceramic of the present application is simple, short in preparation time, and low in energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The XRD patterns of gadolinium zirconate ceramics with different components prepared in the present application and comparative example 1 are shown.

[0036] Figure 2 The SEM image of the surface of the x=-0.5 component (Gd2Zr5O12) gadolinium zirconate ceramic prepared in example 1 of the present application based on non-stoichiometric ratio regulation. 2.5 Zr 1.5 O 6.75 The SEM image of the surface of the x=-0.5 component (Gd2Zr5O12) gadolinium zirconate ceramic prepared in example 1 of the present application based on non-stoichiometric ratio regulation.

[0037] Figure 3 The SEM image of the surface of the x=0 component (Gd2Zr2O7) gadolinium zirconate ceramic prepared in comparative example 1 of the present application based on non-stoichiometric ratio regulation.

[0038] Figure 4 The SEM image of the surface of the x=0.3 component (Gd2Zr5O12) gadolinium zirconate ceramic prepared in example 2 of the present application based on non-stoichiometric ratio regulation. 1.7 Zr 2.3 O 7.15 The SEM image of the surface of the x=0.3 component (Gd2Zr5O12) gadolinium zirconate ceramic prepared in example 2 of the present application based on non-stoichiometric ratio regulation.

[0039] Figure 5 The SEM image of the surface of the x=0.5 component (Gd2Zr5O12) gadolinium zirconate ceramic prepared in example 3 of the present application based on non-stoichiometric ratio regulation. 1.5 Zr 2.5 O 7.25 The SEM image of the surface of the x=0.5 component (Gd2Zr5O12) gadolinium zirconate ceramic prepared in example 3 of the present application based on non-stoichiometric ratio regulation. DETAILED DESCRIPTION

[0040] The present application will be further described below by the following embodiments, and it should be understood that the following embodiments are only used to illustrate the present application, but not to limit the present application.

[0041] Example 1

[0042] Step one: According to the chemical formula Gd 2-x Zr 2+x O 7+x / 2 (x=-0.5) of Gd2O3 and ZrO2 mixed powder. The average particle size of Gd2O3 and ZrO2 used in this embodiment is 1 μm.

[0043] Step two: 40 g of the mixed powder is placed into a zirconium oxide ball mill jar, 80 g of grinding balls with a diameter of 2 mm are added, and finally 120 g of anhydrous ethanol is added as a grinding medium; the ball mill jar is placed in a planetary ball mill for ball milling and mixing. The rotation speed of the ball mill in this embodiment is selected to be 400 r / min, and the ball milling is carried out at this rotation speed for 12 h. After the ball milling is completed, the obtained slurry and grinding balls are separated by using a screen, and the separated slurry is placed in an oven at 90°C for drying. In order to ensure complete drying, the drying time is 10 h.

[0044] Step three: The dried powder is ground in a mortar for 8 minutes, and the grinding direction is changed every 1 min during the grinding. The ground powder is added with PVA with a mass fraction of 5% for granulation treatment.

[0045] Step four: 1.5 g of the granulated powder is weighed and then placed into a tablet press die, the tablet press die is placed on a tablet press machine to apply a pressure of 300 MPa and keep the pressure for 3 min, then the die is removed after the pressure relief of the tablet press machine and the green body is taken out; the green body is placed in a muffle furnace for degassing treatment, the degassing treatment temperature is 600°C, and the holding time is 4 h.

[0046] Step five: The degassed green body is placed into an ultrafast sintering furnace, the heating rate during sintering is 600°C / s, the sintering temperature is 1600°C, and the sintering time is 100 s, and after the sintering is completed, the natural cooling is carried out to room temperature to obtain a gadolinium zirconate ceramic with the chemical formula Gd 2-x Zr 2+ x O 7+x / 2 (x=-0.5).

[0047] Example 2

[0048] Step one: According to the chemical formula Gd 2-x Zr 2+x O 7+x / 2 (x=0.3) of Gd2O3 and ZrO2 mixed powder with an average particle size of 1 μm is weighed.

[0049] Step two: 40g of the mixed powder was put into a zirconia ball mill jar, 80g of grinding balls with a diameter of 2mm was added, and finally 120g of anhydrous ethanol was added as a grinding medium. The ball mill jar was put into a planetary ball mill for ball milling and mixing. The rotation speed of the ball mill was selected to be 350r / min, and the ball milling was carried out at this rotation speed for 10h. After the ball milling was completed, the obtained slurry and grinding balls were separated by using a screen, and the separated slurry was put into an oven at 95°C for drying. In order to ensure complete drying, the drying time was 8h.

[0050] Step three: The dried powder was ground in a mortar for 10 minutes, and the grinding direction was changed every 1min. The ground powder was added with PVA with a mass fraction of 7% for granulation treatment.

[0051] Step four: 2g of the granulated powder was weighed and put into a tablet press mold. The tablet press mold was put on a tablet press to apply a pressure of 350MPa and keep the pressure for 3min. Then the mold was taken off after the pressure relief of the tablet press, and the green body was taken out. The pressed green body was put into a muffle furnace for degassing treatment, and the degassing temperature was 650°C with a holding time of 5h.

[0052] Step five: The degassed green body was put into an ultrafast sintering furnace, the heating rate was 800°C / s, the sintering temperature was 1620°C, and the sintering time was 120s. Then the sample was taken out after sintering.

[0053] Example 3

[0054] Step one: According to the chemical formula Gd 2-x Zr 2+x O 7+x / 2 (x=0.5), the mixed powder of Gd2O3 and ZrO2 was weighed. The average particle size of Gd2O3 and ZrO2 used in this example was 1μm.

[0055] Step two: 40g of the mixed powder was put into a zirconia ball mill jar, 80g of grinding balls with a diameter of 2mm was added, and finally 120g of anhydrous ethanol was added as a grinding medium. The ball mill jar was put into a planetary ball mill for ball milling and mixing. The rotation speed of the ball mill was selected to be 350r / min, and the ball milling was carried out at this rotation speed for 10h. After the ball milling was completed, the obtained slurry and grinding balls were separated by using a screen, and the separated slurry was put into an oven at 95°C for drying. In order to ensure complete drying, the drying time was 8h.

[0056] Step three: The dried powder was ground in a mortar for 10 minutes, and the grinding direction was changed every 1min. The ground powder was added with PVA with a mass fraction of 7% for granulation treatment.

[0057] Step four: 1.5 g of the granulated powder was weighed and put into a tabletting die, the tabletting die was put into a tabletting machine to apply a pressure of 350 MPa and keep the pressure for 2 min, then the die was taken out after the pressure relief of the tabletting machine and the green body was taken out; the green body was put into a muffle furnace for degassing treatment, the degassing treatment temperature was 600 ℃ and the holding time was 5 h.

[0058] Step five: the degassed green body was put into an ultrafast sintering furnace, the heating rate was 600 ℃ / s, the sintering temperature was 1610 ℃, the sintering time was 110 s, and the sample was taken out after natural cooling to room temperature. 2-x Zr 2+ x O 7+x / 2 (x=0.5) gadolinium zirconate ceramic.

[0059] Example 4

[0060] Step one: according to the chemical formula Gd 2-x Zr 2+x O 7+x / 2 (x=0.1), Gd2O3 and ZrO2 mixed powders with an average particle size of 1 μm were weighed respectively.

[0061] Step two: 40 g of the mixed powder was put into a zirconia ball mill jar, 80 g of grinding balls with a diameter of 2 mm was added, and finally 120 g of anhydrous ethanol was added as a grinding medium. The grinding jar was put into a planetary ball mill for ball milling and mixing. The rotation speed of the ball mill was selected to be 300 r / min, and the ball milling was carried out at this rotation speed for 12 h. After the ball milling was completed, the obtained slurry and grinding balls were separated by a screen, and the separated slurry was put into an oven at 95 ℃ for drying. In order to ensure complete drying, the drying time was 8 h.

[0062] Step three: the dried powder was ground in a mortar for 10 minutes, and the grinding direction was changed every 1 min during the grinding. The ground powder was granulated by adding 7% PVA by mass fraction.

[0063] Step four: 2 g of the granulated powder was weighed and put into a tabletting die, the tabletting die was put into a tabletting machine to apply a pressure of 350 MPa and keep the pressure for 3 min, then the die was taken out after the pressure relief of the tabletting machine and the green body was taken out, and the pressed green body was put into a muffle furnace for degassing treatment, the degassing temperature was 650 ℃ and the holding time was 5 h.

[0064] Step five: the degassed green body was put into an ultrafast sintering furnace, the heating rate was 800 ℃ / s, the sintering temperature was 1620 ℃, the sintering time was 120 s, and the sample was taken out after sintering.

[0065] Example 5

[0066] Step one: according to the chemical formula Gd2-x Zr 2+x O 7+x / 2 (x=-0.1) of Gd2O3 and ZrO2 mixed powders were weighed respectively. The average particle size of Gd2O3 and ZrO2 used in this embodiment was 1.5 μm.

[0067] Step two: 40 g of the mixed powders were put into a zirconium oxide ball mill jar, 80 g of grinding balls with a diameter of 2 mm were added, and finally 120 g of anhydrous ethanol was added as a grinding medium; the ball mill jar was put into a planetary ball mill for ball milling and mixing. The rotation speed of the ball mill in this embodiment was selected to be 400 r / min, and the ball milling was carried out at this rotation speed for 12 h. After the ball milling was completed, the obtained slurry and grinding balls were separated by using a screen, and the separated slurry was put into an oven at 90°C for drying. In order to ensure complete drying, the drying time was 12 h.

[0068] Step three: the dried powders were ground in a mortar for 5 minutes, and the grinding direction was changed every 1 min during the grinding. The ground powders were added with 3% PVA by mass fraction for granulation treatment.

[0069] Step four: 1.5 g of the granulated powders were weighed and then put into a tablet press mold, the tablet press mold was put into a tablet press machine to apply a pressure of 200 MPa and keep the pressure for 5 min, then the tablet press machine was depressurized, the mold was taken out and the green body was taken out; the green body was put into a muffle furnace for degassing treatment, the degassing treatment temperature was 500°C, and the holding time was 6 h.

[0070] Step five: the degassed green body was put into an ultrafast sintering furnace, the heating rate during sintering was 500°C / s, the sintering temperature was 1600°C, the sintering time was 180 s, and after the sintering was completed, the green body was naturally cooled to room temperature to obtain a gadolinium zirconate ceramic with a chemical formula of Gd 2-x Zr 2+ x O 7+x / 2 (x=-0.1).

[0071] Example 6

[0072] Step one: Gd 2-x Zr 2+x O 7+x / 2 (x=-0.3) mixed powders with an average particle size of 0.5 μm were weighed respectively.

[0073] Step two: 40 g of mixed powder was put into a zirconium oxide ball mill tank, 80 g of 2 mm diameter grinding balls were added, and finally 120 g of anhydrous ethanol was added as a grinding medium. The grinding tank was placed in a planetary ball mill for ball milling and mixing. The rotation speed of the ball mill was selected to be 400 r / min, and the ball milling was carried out at this rotation speed for 9 h. After the ball milling was completed, the obtained slurry and grinding balls were separated by using a screen, and the separated slurry was placed in an oven at 100°C for drying. In order to ensure complete drying, the drying time was 10 h.

[0074] Step three: The dried powder was ground in a mortar for 10 minutes, and the grinding direction was changed every 1 min during the grinding. The ground powder was granulated by adding PVA with a mass fraction of 10%.

[0075] Step four: 2 g of the granulated powder was weighed and placed in a tablet press mold. The tablet press mold was placed on a tablet press to apply a pressure of 400 MPa and was kept for 2 min. Then the mold was removed after the pressure relief of the tablet press, and the green body was taken out. The pressed green body was placed in a muffle furnace for degassing treatment at a degassing temperature of 600°C for 5 h.

[0076] Step five: The degassed green body was placed in an ultrafast sintering furnace, the heating rate was 1000°C / s, the sintering temperature was 1650°C, and the sintering time was 60 s. The sample was taken out after sintering.

[0077] Comparative Example 1

[0078] In the preparation of the raw material powder of this comparative example, the stoichiometric ratio of Gd2Zr2O7 was used to prepare the mixed powder of Gd2O3 and ZrO2. The other parameters and process were the same as those of Example 1. 2-x Zr 2+x O 7+x / 2 (x = 0), i.e., the stoichiometric ratio of Gd2Zr2O7 was used to prepare the mixed powder of Gd2O3 and ZrO2. The other parameters and process were the same as those of Example 1.

[0079] Performance test:

[0080] 1) EPMA test: The composition of the sintered sample was tested by electron probe X-ray microanalysis. The test sample was the ceramic sample prepared in each example and comparative example of the application. The test results were calculated, and the theoretical chemical formula of Gd 2-x Zr 2+x O 7+x / 2 (x = -0.5, -0.3, -0.1, 0, 0.1, 0.3, 0.5) was used for material ratioing. The actual value of x after sintering was -0.501, -0.299, -0.100, 0.001, 0.1001, 0.302, 0.499, which was within the allowable range of experimental error and test error, proving that the stoichiometric ratio of the sintered sample was consistent with the raw material ratioing.

[0081] 2) XRD test: As Figure 1 XRD patterns of gadolinium zirconate ceramics with different compositions were prepared for each embodiment of the present application and Comparative Example 1. As can be seen from the figure, the structure of gadolinium zirconate ceramics with different stoichiometric ratios is a single-phase fluorite structure, without the generation of a second phase and other impurities. With the regulation of non-stoichiometric ratio, the XRD peaks of gadolinium zirconate ceramics with different compositions are obviously shifted, which is mainly because with the change of the ratio of A-site and B-site elements, i.e. zirconium and gadolinium elements, the crystal structure of non-stoichiometric gadolinium zirconate ceramics is distorted relative to Gd2Zr2O7, thereby causing the change of lattice constant.

[0082] 3) SEM micro-morphology: The surface micro-morphology of each component of gadolinium zirconate ceramics prepared in each embodiment and comparative example was observed by SEM, and the gadolinium zirconate ceramics prepared by the ultrafast sintering method of the present application showed the characteristics of small and uniform grain size, high density (no obvious pores), and uniform structure in the scanning electron microscope. For example Figures 2-5 The SEM images of the surfaces of gadolinium zirconate ceramics with x = -0.5, 0, 0.3, 0.5 prepared in Example 1, Comparative Example 1, Example 2 and Example 3 of the present application after heat etching treatment, respectively, from which it can be seen that the grain arrangement of gadolinium zirconate ceramics with different stoichiometric ratios after ultrafast sintering is tight, without obvious pores; the grain size is small and uniformly distributed, and the average grain size is 2.7-7.8 μm; with the deviation of stoichiometric ratio, the degree of grain growth of the sample becomes larger, which is mainly because the deviation of stoichiometric ratio introduces a large number of controllable defects and oxygen vacancies, and enhances the ion migration ability of the material; this also shows that the structure defect regulation mechanism of composition deviation and the diffusion / activation behavior under the induction of strong thermal field in the present application work synergistically, significantly reduces the energy barrier of ceramic phase formation, strengthens the ion migration rate, and realizes rapid crystallization and uniform single-phase formation in a very short time.

[0083] 4) Other physical performance tests

[0084] The physical properties of gadolinium zirconate ceramics prepared in each embodiment and comparative example were tested. The test results showed that, compared with the gadolinium zirconate ceramic prepared in Comparative Example 1 that met the stoichiometric ratio of Gd2Zr2O7, the non-stoichiometric gadolinium zirconate ceramics prepared in each embodiment of the present invention showed improved thermal stability and corrosion resistance. This confirms that the non-stoichiometric component ratio of the gadolinium zirconate ceramics of the present invention introduces a large number of controllable antisite defects and oxygen vacancies, effectively broadening the structural control dimension of the material. At the same time, the use of ultrafast sintering technology, under the strong external thermal field induction of ultrafast sintering, the defect control mechanism caused by the non-stoichiometric structural design and the diffusion / activation behavior induced by the strong external thermal field work together to significantly reduce the energy barrier for ceramic phase formation, enhance the ion migration rate, and achieve rapid crystallization and uniform single-phase formation in a very short time. Thus, gadolinium zirconate ceramics based on non-stoichiometric ratio with enhanced ion migration performance, thermal stability and corrosion resistance are obtained. For example, the gadolinium zirconate ceramic Gd₂Zr₂O₇ prepared in Comparative Example 1 had a relative density of 97.12%, a hardness of 9.43 GPa, a Young's modulus of 205 GPa, and a coefficient of thermal expansion of 9.72 × 10⁻⁶. -6 K -1 The thermal conductivity at 1300℃ is 2.25 W / (m·K). Example 1 shows the preparation of Gd. 2-x Zr 2+x O 7+x / 2 (x=-0.5)(Gd) 2.5 Zr 1.5 O 6.75 The gadolinium zirconate ceramic was measured to have a relative density of 96.56%, a hardness of 10.52 GPa, a Young's modulus of 228 GPa, and a coefficient of thermal expansion of 9.56 × 10⁻⁶. -6 K -1 The thermal conductivity at 1300℃ is 1.93 W / (m·K). Another example is the Gd prepared in Example 2. 1.7 Zr 2.3 O 7.15 Non-stoichiometric rare-earth zirconate ceramics have a relative density of 97.78%, a hardness of 11.03 GPa, a Young's modulus of 230 GPa, and a coefficient of thermal expansion of 9.84 × 10⁻⁶. -6 K -1 Its thermal conductivity at 1300℃ is 1.89 W / (m·K).

Claims

1. A gadolinia ceramic based on non-stoichiometric regulation, characterized in that: The chemical formula of the gadolinium zirconate ceramic is Gd 2-x Zr 2+x O 7+x / 2 , wherein 0.5≥x≥-0.5, and x≠0; the gadolinium zirconate ceramic based on non-stoichiometric ratio regulation has a single fluorite structure; compared with the XRD pattern peak position of the gadolinium zirconate ceramic Gd2Zr2O7, the XRD pattern peak position of the gadolinium zirconate ceramic based on non-stoichiometric ratio regulation is shifted; crystal structure defect states are introduced; the micro-morphology of the gadolinium zirconate ceramic based on non-stoichiometric ratio regulation has no obvious holes, the crystal grains are small and uniform, and the average size of the crystal grains is 2.7~7.8 μm; The gadolinium zirconate ceramic is prepared by an ultrafast sintering method, the ultrafast sintering has a temperature rising rate of 500-1000 ℃ / s, a sintering temperature of 1600-1650 ℃ and a sintering time of 60-180 s.

2. The gadolinium zirconate ceramic based on non-stoichiometric regulation according to claim 1, characterized in that: And with the increase of the deviation degree of the stoichiometric ratio, the degree of grain growth becomes larger.

3. The method for preparing gadolinium zirconate ceramic based on non-stoichiometric control according to any one of claims 1-2, characterized in that, The method comprises the following steps: Step one, according to the chemical formula Gd 2-x Zr 2+x O 7+x / 2 The Gd2O3 and ZrO2 mixed powder is prepared according to the measurement ratio of the chemical formula Gd2-xZrxO4; wherein 0.5≥x≥-0.5, and x≠0. Step two, the weighed mixed powder is ball milled and uniformly mixed, and the obtained slurry is dried in an oven after ball milling; Step three, the dried powder is manually ground, and then the powder is granulated; Step four, the granulated powder is put into a tablet pressing mold, the tablet pressing mold is put on a tablet press for pressing and pressure maintaining for a period of time, and the pressed green body is put into a muffle furnace for degassing treatment; Step five, the degassed green body is put into an ultrafast sintering furnace for ultrafast sintering, and the gadolinium zirconate ceramic based on non-stoichiometric ratio regulation and control is prepared after sintering.

4. The method for preparing gadolinium zirconate ceramic based on non-stoichiometric control according to claim 3, characterized in that: In step one, the particle size of the Gd2O3 and ZrO2 powders is 500 nm-1500 nm.

5. The method for preparing gadolinium zirconate ceramic based on non-stoichiometric control according to claim 3, characterized in that: In step two, the ball milling speed is 300-500 r / min, the ball milling time is 8-12 h, the drying temperature is 90-100 ℃, and the drying time is 8-12 h.

6. The method of claim 3, wherein the method is characterized by: In step three, the manual grinding time is 5-10 min, and 3-10% PVA is added during powder granulation.

7. The method of claim 3, wherein the method is characterized by: In step four, the pressing pressure is 200-400 MPa, the pressing time is 2-5 min, the degassing temperature is 500-650 ℃, and the degassing time is 4-6 h.

8. The method of claim 3, wherein the gadolinium zirconate ceramic is prepared by a non-stoichiometric ratio control method. In step five, the ultrafast sintering furnace has a temperature rising rate of 500-1000 ℃ / s, a sintering temperature of 1600-1650 ℃, and a sintering time of 60-180 s, and the sintering is naturally cooled after sintering.

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