Preparation method of alkaline earth metal tantalate AETa2O6 ceramic material

Abstract

The invention discloses a preparation method of an alkaline earth metal tantalate AETa2O6 ceramic material, and relates to ceramic material preparation, and the preparation method comprises the following steps: drying Ta2O5 and oxide powder, mixing, and carrying out ball milling to obtain mixed powder; performing constant-temperature drying and sieving on the mixed powder, pre-sintering the sieved powder to obtain pre-sintered powder, and grinding and sieving the pre-sintered powder; carrying out secondary ball milling on the sieved pre-sintered powder and then carrying out constant-temperature drying to obtain mixed powder; tabletting the mixed powder, then carrying out hot-pressing calcination, and after the hot-pressing calcination is finished, cooling to room temperature to obtain a ceramic chip; and carrying out high-temperature annealing on the ceramic wafer to obtain the compact AETa2O6 ceramic wafer. According to the invention, the rare earth tantalate ceramic material is directly prepared by a solid phase method, and the rare earth tantalate ceramic material has the advantages of simple synthesis, convenient operation and easy further processing, so that the rare earth tantalate ceramic material has the properties of high density, high temperature resistance, corrosion resistance and the like, and a new direction is provided for expanding the application of high-density rare earth tantalate.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic material preparation, and particularly relates to a preparation method of alkaline earth metal tantalate AETa2O6 ceramic material. Background Art

[0002] With the leapfrog evolution of the fourth-generation aero-engine and heavy-duty gas turbine towards the "dual high" (high thrust-to-weight ratio and high temperature rise) technical indicators, the service temperature of hot-end components has exceeded the critical threshold of 1500 °C. Under this ultra-high temperature-high stress coupling working condition, the nickel-based single-crystal alloy substrate faces a triple failure mechanism of high-temperature oxidation, molten salt hot corrosion, and cyclic thermo-mechanical load, posing dual technical requirements for the multi-field coupling protection performance of the thermal barrier-environmental barrier integrated coating: it is necessary to have both the thermal insulation function of traditional thermal barrier coatings (TBCs) and the anti-medium erosion characteristics of environmental barrier coatings (EBCs).

[0003] Although the thermal barrier materials represented by rare earth tantalate AETaO4 partially meet the basic performance requirements, there are significant technical bottlenecks in the synergistic optimization of "high thermal insulation - anti-corrosion - high-temperature phase stability". First, when treated by conventional solid-phase sintering at 1500 - 1600 °C, the formation of Ta2O5 metastable phase leads to grain boundary impurity segregation, resulting in insufficient material density (<95%) and a more than 15% decrease in Vickers hardness. Secondly, there is an imbalance between thermal and mechanical properties. The high elastic modulus (>200 GPa) limits the thermal stress release ability, leading to the generation of microcracks at the coating / substrate interface and causing delamination failure (the thermal cycle life is reduced by 30% - 40%); thirdly, the structure regulation is rigid, and it is difficult to achieve the synergistic optimization of thermal conductivity (κ < 2.5 W·m -1 ·K -1 ) and coefficient of thermal expansion (CTE ≈ 9.8×10 -6 K -1 ) through chemical bond regulation in a single fluorite-type structure.

[0004] The new AETa2O6 system shows unique advantages through crystal engineering regulation. One is the low-dimensional heat conduction inhibition mechanism: constructing a layered oxygen vacancy ordered structure and Ta-O octahedron distortion, combined with the blocking effect of the six-coordination network on oxygen ion migration, to achieve ultra-low thermal conductivity (κ < 1.5 W·m -1 ·K -1 , with a decrease of >25%); the other is the thermal-mechanical property synergy: using the rare earth ion radius gradient to regulate the lattice distortion degree and achieve precise CTE matching (10.5 - 12.5×10 -6 K -1)Optimization of elastic modulus (E≈180GPa, with a decrease of >10%); thirdly, a significant improvement in corrosion resistance: the dense grain boundaries and chemically inert surface reduce the molten salt penetration rate to 0.2μm / h, which is two orders of magnitude higher than that of the YSZ system; fourthly, enhanced interfacial thermal matching: the average CTE in the range of RT-1200°C reaches 11.2×10 -6 K -1 , and the mismatch with the nickel-based alloy substrate (12.5×10 -6 K -1 ) is 58% lower than that of YSZ.

[0005] However, the key factor restricting the practical application of the AETa2O6 system currently lies in the bottleneck of the preparation process. The existing preparation technologies severely restrict the performance improvement. Firstly, there is the problem of high-temperature densification: traditional solid-state sintering requires high-temperature treatment above 1750°C, but the density is only 92%-95%, and the residual porosity (>3%) becomes the preferential path for molten salt penetration; secondly, the control of element segregation. The diffusion kinetic differences between AE and Ta during the high-temperature synthesis process lead to grain boundary segregation, exacerbating the interfacial stress concentration.

[0006] Therefore, reducing the sintering temperature, improving the density, suppressing element segregation, and enhancing the corrosion resistance through external field assistance have become the key technical paths for realizing the engineering application of ultra-high-temperature thermal barrier coatings. Summary of the Invention

[0007] The purpose of the present invention is to provide a preparation method for an alkaline earth metal tantalate AETa2O6 ceramic material with high density, high temperature resistance, and corrosion resistance to solve the above problems existing in the prior art.

[0008] To achieve the above purpose, a preparation method for an alkaline earth metal tantalate AETa2O6 ceramic material provided by the present invention is characterized by including the following steps:

[0009] (1) Dry the Ta2O5 and AEO oxide powders and set aside; drying is carried out to remove trace moisture and other impurities adsorbed in the air, ensuring the purity of the raw materials and facilitating accurate later proportioning;

[0010] (2) Mix the Ta2O5 and oxide powders and then carry out ball milling to obtain mixed powders;

[0011] (3) Carry out constant-temperature drying on the mixed powders, then sieve them, pre-sinter the sieved powder bodies to obtain pre-sintered powder bodies, grind the pre-sintered powder bodies and then sieve them;

[0012] (4) Carry out secondary ball milling on the sieved pre-sintered powder bodies and then carry out constant-temperature drying. After drying, sieve them twice to obtain mixed powder bodies;

[0013] (5) Press the mixed powder into tablets and then perform hot-pressing calcination. After the hot-pressing calcination is completed and cooled to room temperature, a ceramic sheet is obtained;

[0014] (6) Anneal the ceramic sheet at high temperature, and a dense AETa2O6 ceramic sheet is obtained.

[0015] The chemical equation of this method is: Ta2O5 + AEO = AETa2O6

[0016] Specifically, the drying in steps (1), (3), and (4) is carried out at 60 - 80 °C for 12 - 24 h.

[0017] Specifically, AE in the AEO oxide powder in step (1) is one of Ca, Mg, Sr, and Ba.

[0018] Specifically, the molar ratio of Ta2O5 to the oxide powder in step (2) is 1:1 - 1.5.

[0019] Specifically, in step (2), the ball milling is carried out at a ball milling speed of 200 - 500 r / min, with a forward and reverse rotation time of 15 - 30 min, no pause, and a ball milling time of 12 - 24 h.

[0020] Specifically, the grinding time in step (3) is 5 - 10 min, and the sieving mesh number is 100 - 300 meshes;

[0021] Specifically, in step (4), the secondary ball milling speed is 200 - 400 r / min, the forward and reverse rotation time is 15 - 30 min, no pause, the secondary sieving mesh number is 200 - 400 meshes, and the secondary ball milling time is 6 - 12 h.

[0022] Specifically, the pre-calcination in step (3) is carried out at 1200 - 1400 °C for 1 - 4 hours; when pre-calcining, the heating rate at 50 - 1000 °C is 8 - 12 °C / min, the heating rate at 1000 - 1400 °C is 4 - 8 °C / min, with insulation for 20 - 30 min at 1000 °C and insulation for 20 - 30 min at 1200 °C.

[0023] Specifically, the hot-pressing calcination in step (5) is carried out at a pressure of 80 - 120 MPa and a temperature of 1550 - 1650 °C for 1 - 2 h; when hot-pressing calcining, the heating rate at 50 - 1400 °C is 8 - 10 °C / min, the heating rate at 1400 - 1550 °C is 6 - 10 °C / min, and the pressure changes with temperature in a parabolic shape, with the maximum pressure at the highest temperature.

[0024] Specifically, the high-temperature annealing in step (6) is carried out at 1250 - 1400 °C for 4 - 8 h; when performing high-temperature annealing, the heating rate from 50 - 1000 °C is 8 - 12 °C / min, and the heating rate from 1000 - 1400 °C is 4 - 8 °C / min, with insulation for 10 - 30 min at 1000 °C and insulation for 10 - 30 min at 1200 °C.

[0025] The advantages or beneficial effects in the above technical solutions at least include:

[0026] (1) Through pre-sintering, AETa2O6 ceramic powder with uniform reaction can be preferentially generated. By performing secondary ball milling on the pre-sintered powder, the ceramic powder particles can be made more uniform and refined. Then, using a hot press furnace for sintering the ceramic sheet, compared with traditional muffle furnace sintering, hot press sintering, under the action of hot isostatic pressing, makes the ceramic sheet more dense, reduces the generation of pores on the microscopic surface, and ultimately can effectively improve its hardness and density, enhancing the ability to resist CMAS corrosion.

[0027] (2) The high-density, high-temperature-resistant, and corrosion-resistant rare-earth tantalate AETa2O6 ceramic material of the present invention has a thermal expansion coefficient (at 1200 °C, 10.8×10 –6 K -1 ) higher than that of YSZ (at 1200 °C, 10.2 -6 k -1 ), and is closer to the thermal expansion coefficient of the substrate (nickel-based, 13 - 16×10 –6 K -1 ), reducing the cracking and peeling of the coating caused by the mismatch of thermal expansion coefficients.

[0028] (3) The high-density, high-temperature-resistant, and corrosion-resistant rare-earth tantalate AETa2O6 ceramic material of the present invention has an oxygen ion conductivity (at 600 - 900 °C, 0.1 - 2.1×10 -5 S·cm -1 ) much smaller than that of YSZ (at 1000 °C, 0.01 S·cm -1 ). The low conductivity means low oxygen ion transport and high oxygen insulation, thus effectively inhibiting the excessive growth of TGO, contributing to suppressing the growth of TGO and reducing the peeling probability between the coating and TGO. In addition, its activation energy of 1.473 eV is higher than that of 8YSZ (1.125 eV). The higher the activation energy, the higher the energy required for a chemical reaction to occur, and the more stable the system. The higher activation energy makes the system more stable.

[0029] (4) The conductivity of the high-density, high-temperature-resistant, and corrosion-resistant rare-earth tantalate AETa2O6 ceramic material of the present invention at high temperature (at 200 - 900 °C, 1.75 - 2.23 W·m -1 ·K -1)Far lower than 7 - 8YSZ (2.83 - 3.15 W·m -1 ·K -1 ) and AETaO4 (AE = Nd, Eu, Gd, Dy, Er, Yb, Lu) (1.4 - 3.5 W·m -1 ·K -1 ), the main reason is that the constructed layered oxygen vacancy ordered structure and Ta - O octahedron distortion, combined with the blocking effect of the six - coordinate network on oxygen ion migration, thus achieving ultra - low thermal conductivity.

[0030] (5) The conductivity of the high - density, high - temperature - resistant, and corrosion - resistant rare - earth tantalate AETa2O6 ceramic material of the present invention is significantly improved by two orders of magnitude in corrosion resistance compared to the YSZ system, mainly due to its preparation process, which makes the AETa2O6 material have a high density, and the denser its structure, the better its corrosion resistance, reducing the penetration path of molten salt. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the flow chart of the preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material of the present invention;

[0032] Figure 2 is the XRD pattern of the high - density, high - temperature - resistant, and corrosion - resistant strontium tantalate SrTa2O6 high - temperature ceramic prepared in Example 1 of the present invention;

[0033] Figure 3 is the SEM comparison diagram of the high - density, high - temperature - resistant, and corrosion - resistant strontium tantalate SrTa2O6 prepared in Example 1 of the present invention and the SrTa2O6 ceramic prepared conventionally;

[0034] Figure 4 is the anti - CMAS corrosion comparison diagram of the high - density, high - temperature - resistant, and corrosion - resistant strontium tantalate SrTa2O6 prepared in Example 1 of the present invention and the SrTa2O6 ceramic prepared conventionally;

[0035] Figure 5 is the EDS diagram of the element distribution comparison of the high - density, high - temperature - resistant, and corrosion - resistant strontium tantalate SrTa2O6 prepared in Example 1 of the present invention and the SrTa2O6 ceramic prepared conventionally. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention. In the description of the present invention, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0037] Example 1

[0038] This example provides a preparation method for an alkaline earth metal tantalate SrTa2O6 ceramic material with high density, high temperature resistance, and corrosion resistance, including the following steps:

[0039] S1 Raw material drying: Put the raw materials Ta2O5 and SrO powder into a drying oven and dry at 70 °C for 18 h to remove trace moisture and other impurities adsorbed in the air, ensure the purity of the raw materials, and facilitate accurate later proportioning;

[0040] S2 Weighing and ball milling: Weigh 22.095 g of Ta2O5 and 5.181 g of SrO powder respectively. Its chemical equation is: Ta2O5 + SrO = SrTa2O6, and carry out ball milling for 16 h under the conditions of a rotation speed of 400 r / min, a forward and reverse rotation time of 20 min, and 0 stay.

[0041] S3 Preliminary pre-sintering: Place the mixed powder in a drying oven for constant temperature drying at a drying temperature of 70 °C for 18 h; after drying, pass it through a 200-mesh sieve, place the sieved powder in a ceramic boat, and place it in a muffle furnace for pre-sintering at 1250 °C for 4 hours. Among them, the heating rate of the muffle furnace from 50 - 1000 °C is 10 °C / min, and the heating rate from 1000 - 1250 °C is 6 °C / min. Among them, keep the temperature constant for 25 min at 1000 °C and 25 min at 1250 °C.

[0042] S4 Grinding and granulation: Grind the pre-sintered powder for 8 min and then pass it through a 200-mesh sieve. Carry out secondary ball milling on the sieved powder for 8 h under the conditions of a rotation speed of 300 r / min, a forward and reverse rotation time of 25 min, and 0 stay. Place the mixed powder in a drying oven for constant temperature drying at a drying temperature of 70 °C for 20 h; after drying, pass it through a 200-mesh sieve for the second time.

[0043] S5 Hot pressing and sheet sintering: Weigh an appropriate amount of the sieved powder and place it in a graphite sheet pressing mold. Place the mold in a hot pressing furnace and calcine at 90 MPa pressure and 1580 °C for 1 h. During calcination, the heating rate from 50 - 1400 °C is 8 - 10 °C / min, and the heating rate from 1400 - 1580 °C is 6 - 10 °C / min. The pressure changes with temperature as a parabola, and the pressure is the largest at the highest temperature.

[0044] S6 High-temperature annealing: After the hot pressing furnace cools down, take out the sintered ceramic sheet, place it in a muffle furnace for annealing at 1280 °C for 6 h to obtain a dense SrTa2O6 ceramic sheet. Among them, the heating rate of the muffle furnace from 50 - 1000 °C is 8 - 12 °C / min, and the heating rate from 1000 - 1280 °C is 4 - 8 °C / min. Among them, keep the temperature constant for 10 - 30 min at 1000 °C and 10 - 30 min at 1280 °C.

[0045] The prepared hot-pressed sintered SrTa2O6 ceramic sheet was subjected to XRD testing. The scanning speed was set at 5° / min, and the scanning range was 10 - 70. The scanning results were refined to obtain Figure 2 the XRD refined pattern shown in (a). It can be seen from the figure that the crystallinity of the prepared sample is very good, and through its results, Figure 2 the molecular structure diagram shown in (b) was obtained.

[0046] Comparative Example 1

[0047] Weigh 22.095 g of Ta2O5 and 5.181 g of SrO powders respectively, and carry out ball milling for 16 h. The mixed powder was placed in a drying oven for constant-temperature drying. The drying temperature was 70 °C and the duration was 18 h. After drying, it was sieved through a 200-mesh sieve. Then it was pressed into tablets by a tablet press mold, and the obtained tablets were put into a muffle furnace and calcined at 1580 °C for 1 h to obtain non-dense SrTa2O6 ceramic sheets.

[0048] The ceramic sheets prepared in Example 1 and Comparative Example 1 were observed for their microtopography by scanning electron microscopy. The SEM image of the SrTa2O6 ceramic sheet prepared in Example 1 is as shown in Figure 3 (a), and the SEM image of the ceramic sheet prepared in Comparative Example 1 is as shown in Figure 3 (b). It can be seen from Figure 3 (a) that the cell size of the ceramic sheet obtained by the preparation method of the present invention is uniform, there are no obvious pores on the surface, and the density is good; Figure 3 (b) The cell sizes of the ceramic sheets prepared by the conventional process are not uniform, and there are a large number of pores on the surface, and the density is poor.

[0049] The ceramic sheets prepared in Example 1 and Comparative Example 1 were subjected to surface anti-CMAS corrosion testing. The testing method was to mix a certain proportion of CMAS powder with absolute ethanol into a slurry state, evenly apply it on the surface of the ceramic sheet, and after it dried, put the ceramic sheet into a muffle furnace and keep it at 1300 °C for 2 hours. After it cooled, a cross-section was cut, and the cross-section was polished smoothly. The corrosion cross-section as shown in Figure 4 was obtained through backscattered imaging of the scanning electron microscope. Figure 4 (a) and 4(b) are the corrosion cross-section diagrams of the ceramic sheets of Example 1 and Comparative Example 1 respectively. By comparison, it can be seen that the ceramic sheet prepared in Example 1 has good corrosion resistance. The CMAS powder did not melt into the ceramic sheet at high temperature, and there is an obvious interface on the surface of the ceramic sheet; while the ceramic sheet of Comparative Example 1 has poor corrosion resistance.

[0050] The ceramic wafers prepared in Example 1 and Comparative Example 1 were subjected to EDS surface scanning. The EDS diagrams comparing the elemental distributions of highly dense, high-temperature resistant, and corrosion-resistant strontium tantalate SrTa2O6 and conventionally prepared SrTa2O6 ceramics are as Figure 5 shown. Figure 5 (a) and (b) are the ceramic wafers prepared in Example 1 and Comparative Example 1, respectively. It can be seen that the elemental distribution of the sample prepared in Example 1 is uniform, indicating that the reaction is complete and there are no segregation phenomena. However, segregation exists in the conventionally sintered ceramic wafer.

[0051] Example 2

[0052] This example provides a method for preparing a highly dense, high-temperature resistant, and corrosion-resistant alkaline earth metal tantalate CaTa2O6 ceramic material, which includes the following steps:

[0053] S1 Raw material drying: Put the raw material Ta2O5 and CaO oxide powders into a drying oven and dry them at 80°C for 12 h to remove trace moisture and other impurities adsorbed in the air, ensure the purity of the raw materials, and facilitate accurate later mixing.

[0054] S2 Weighing and ball milling: Weigh 22.095 g of Ta2O5 and 2.804 g of CaO powders respectively. The chemical equation is: Ta2O5 + CaO = CaTa2O6, and carry out ball milling for 24 h under the conditions of a rotation speed of 500 r / min, a forward and reverse rotation time of 15 min, and no pause.

[0055] S3 Preliminary pre-sintering: Place the mixed powder in a drying oven for constant-temperature drying at a temperature of 80°C for 12 h; after drying, pass it through a 400-mesh sieve, place the sieved powder in a ceramic boat, and place it in a muffle furnace for pre-sintering at 1400°C for 3 hours. The heating rate of the muffle furnace from 50 to 1000°C is 10°C / min, and the heating rate from 1000 to 1400°C is 6°C / min. Keep the temperature at 1000°C for 25 min and at 1400°C for 25 min.

[0056] S4 Grinding and granulation: Grind the pre-sintered powder for 10 min and then pass it through a 400-mesh sieve. Carry out secondary ball milling on the sieved powder for 12 h under the conditions of a rotation speed of 400 r / min, a forward and reverse rotation time of 30 min, and no pause. Place the mixed powder in a drying oven for constant-temperature drying at a drying temperature of 80°C for 12 h; after drying, pass it through a 400-mesh sieve for the second time.

[0057] S5 Hot Pressing and Sintering: Weigh an appropriate amount of the sieved powder and place it in a graphite pressing die. Put the die in a hot press furnace and calcine it at 100 MPa pressure and 1650 °C for 2 h. During the calcination, the heating rate is 8 - 10 °C / min from 50 - 1400 °C and 6 - 10 °C / min from 1400 - 1650 °C. The pressure changes with temperature in a parabolic shape, and the pressure is the maximum at the highest temperature.

[0058] S6 High - temperature Annealing: After the hot press furnace cools down, take out the sintered ceramic sheet and place it in a muffle furnace for annealing at 1400 °C for 8 h to obtain a dense CaTa2O6 ceramic sheet. Among them, the heating rate of the muffle furnace is 8 - 12 °C / min from 50 - 1000 °C and 4 - 8 °C / min from 1000 - 1400 °C. Keep it at 1000 °C for 10 - 30 min and at 1400 °C for 10 - 30 min.

[0059] Example 3

[0060] This example provides a preparation method for an alkaline earth metal tantalate MgTa2O6 ceramic material with high density, high temperature resistance, and corrosion resistance, including the following steps:

[0061] S1 Raw Material Drying: Put the raw materials Ta2O5 and MgO powders into a drying oven and dry them at 60 °C for 12 h to remove trace moisture and other impurities adsorbed in the air, ensure the purity of the raw materials, and facilitate accurate later proportioning;

[0062] S2 Weighing and Ball Milling: Weigh 22.095 g of Ta2O5 and 2.015 g of MgO powders respectively. The chemical equation is: Ta2O5 + MgO = MgTa2O6, and carry out ball milling for 6 h under the conditions of a rotation speed of 200 r / min, a forward - reverse rotation time of 15 min, and no stop.

[0063] S3 Preliminary Pre - sintering: Place the mixed powder in a drying oven for constant - temperature drying. The drying temperature is 60 °C and the duration is 12 h; after drying, sieve it through a 300 - mesh sieve, place the sieved powder in a ceramic boat, and put it in a muffle furnace for pre - sintering at 1200 °C for 4 hours. Among them, the heating rate of the muffle furnace is 10 °C / min from 50 - 1000 °C and 6 °C / min from 1000 - 1200 °C. Keep it at 1000 °C for 25 min and at 1200 °C for 20 min.

[0064] S4 Grinding and Granulation: Grind the pre - sintered powder for 5 min and then sieve it through a 300 - mesh sieve. Carry out secondary ball milling for 6 h on the sieved powder under the conditions of a rotation speed of 200 r / min, a forward - reverse rotation time of 15 min, and no stop. Place the mixed powder in a drying oven for constant - temperature drying. The drying temperature is 60 °C and the duration is 12 h; after drying, sieve it through a 300 - mesh sieve again.

[0065] S5 Hot pressing and sintering: Weigh an appropriate amount of sieved powder and place it in a graphite pressing die. Place the die in a hot pressing furnace and calcine it at 120 MPa pressure and 1550 °C for 1 h. During calcination, the heating rate from 50 - 1400 °C is 8 - 10 °C / min, and the heating rate from 1400 - 1550 °C is 6 - 10 °C / min. The pressure changes with temperature in a parabolic shape, with the maximum pressure at the highest temperature.

[0066] S6 High - temperature annealing: After the hot pressing furnace cools down, take out the sintered ceramic sheet and place it in a muffle furnace for annealing at 1250 °C for 4 h to obtain a dense MgTa2O6 ceramic sheet. Among them, the heating rate of the muffle furnace from 50 - 1000 °C is 8 - 12 °C / min, and the heating rate from 1000 - 1250 °C is 4 - 8 °C / min. Keep it at 1000 °C for 10 - 30 min and at 1250 °C for 10 - 30 min.

[0067] Example 4

[0068] This example provides a preparation method of an alkaline earth metal tantalate BaTa2O6 ceramic material with high density, high temperature resistance, and corrosion resistance, including the following steps:

[0069] S1 Raw material drying: Put the raw material Ta2O5 and BaO oxide powders into a drying oven and dry them at 80 °C for 12 h to remove trace moisture and other impurities adsorbed in the air, ensure the purity of the raw materials, and facilitate accurate later proportioning;

[0070] S2 Weighing and ball milling: Weigh 22.095 g of Ta2O5 and 7.666 g of BaO powders respectively. The chemical equation is: Ta2O5 + BaO = BaTa2O6, and carry out ball milling for 12 h.

[0071] S3 Preliminary pre - sintering: Place the mixed powder in a drying oven for constant - temperature drying. The drying temperature is 70 °C and the duration is 18 h; after drying, sieve it through a 200 - mesh sieve. Place the sieved powder in a ceramic boat and put it in a muffle furnace for pre - sintering at 1300 °C for 3 hours. Among them, the heating rate of the muffle furnace from 50 - 1000 °C is 10 °C / min, and the heating rate from 1000 - 1300 °C is 6 °C / min. Keep it at 1000 °C for 20 min and at 1300 °C for 25 min.

[0072] S4 Grinding and granulation: Grind and sieve the pre - sintered powder, carry out secondary ball milling on the sieved powder for 10 h, place the mixed powder in a drying oven for constant - temperature drying, the temperature is 80 °C and the duration is 12 h; after drying, sieve it again.

[0073] S5 Hot Pressing and Sintering: Weigh an appropriate amount of the sieved powder and place it in a graphite pressing die. Put the die in a hot press furnace and sinter it at a pressure of 110 MPa and a temperature of 1600 °C for 2 h.

[0074] S6 High-temperature Annealing: After the hot press furnace cools down, take out the sintered ceramic piece and place it in a muffle furnace for annealing at 1300 °C for 4 h to obtain a dense BaTa2O6 ceramic piece.

[0075] Test the ceramic pieces prepared in Examples 2-4, and they also have the advantages of high density, high temperature resistance, and corrosion resistance.

[0076] In summary, through pre-sintering, the present invention can preferentially generate AETa2O6 ceramic powder with uniform reaction. In S4, the ceramic powder generated in S3 is subjected to secondary ball milling, which can make the ceramic powder particles more uniform and finer. In S5, a hot press furnace is used for sintering the ceramic piece. Compared with traditional muffle furnace sintering, hot press sintering under the action of hot isostatic pressing makes the ceramic piece more dense, reduces the generation of pores on the microscopic surface, and ultimately can effectively improve its hardness and density, and enhance the ability to resist CMAS corrosion.

[0077] What is disclosed above is only some embodiments of the present invention, and the scope of rights of the present invention cannot be limited thereby. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A method for preparing an alkaline earth metal tantalate AETa2O6 ceramic material, characterized in that: It includes the following steps: (1) Dry Ta2O5 and AEO oxide powders and set aside for later use; (2) Mix Ta2O5 with the oxide powders and then carry out ball milling to obtain mixed powders; (3) After the mixed powders are dried at a constant temperature, sieve them. Subject the sieved powder to pre-sintering to obtain the pre-sintered powder, grind the pre-sintered powder and then sieve it; (4) Carry out secondary ball milling on the pre-sintered powder after sieving and then dry it at a constant temperature. After drying, sieve it twice to obtain mixed powders; (5) Press the mixed powders into tablets and then carry out hot-pressing calcination. After the hot-pressing calcination is completed and cooled to room temperature, obtain ceramic wafers; (6) Carry out high-temperature annealing on the ceramic wafers to obtain dense AETa2O6 ceramic wafers.

2. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, The drying in steps (1), (3), and (4) is carried out at 60 - 80°C for 12 - 24 h.

3. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, In the AEO oxide powder in step (1), AE is one of Ca, Mg, Sr, and Ba.

4. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, The molar ratio of Ta2O5 to the oxide powder in step (2) is 1:1 - 1.

5.

5. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, In step (2), the ball milling is carried out at a ball milling speed of 200 - 500 r / min, with a forward and reverse rotation time of 15 - 30 min, no pause, and a ball milling time of 12 - 24 h.

6. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, In step (3), the grinding time is 5 - 10 min, and the sieve mesh numbers for sieving are both 100 - 300 meshes.

7. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, In step (4), the secondary ball milling speed is 200 - 400 r / min, with a forward and reverse rotation time of 15 - 30 min, no pause, the secondary sieve mesh number is 200 - 400 meshes, and the secondary ball milling time is 6 - 12 h.

8. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, The pre-sintering in step (3) is carried out at 1200 - 1400°C for 1 - 4 hours; during pre-sintering, the heating rate from 50 - 1000°C is 8 - 12°C / min, the heating rate from 1000 - 1400°C is 4 - 8°C / min, where it is held at 1000°C for 20 - 30 min and at 1200°C for 20 - 30 min.

9. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, The hot-pressing calcination in step (5) is carried out at a pressure of 80 - 120 MPa and a temperature of 1550 - 1650°C for 1 - 2 h; during hot-pressing calcination, the heating rate from 50 - 1400°C is 8 - 10°C / min, and the heating rate from 1400 - 1550°C is 6 - 10°C / min.

10. The preparation method of the alkaline earth metal tantalate AETa2O6 ceramic material according to claim 1, characterized in that, The high-temperature annealing in step (6) is carried out at 1250 - 1400°C for 4 - 8 h; during high-temperature annealing, the heating rate from 50 - 1000°C is 8 - 12°C / min, the heating rate from 1000 - 1400°C is 4 - 8°C / min, where it is held at 1000°C for 10 - 30 min and at 1200°C for 10 - 30 min.

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