A high-density, high-temperature-resistant, corrosion-resistant rare earth tantalate ceramic material and a preparation method thereof

Abstract

The application discloses a kind of high density, high temperature resistant, corrosion resistant rare earth tantalate RETaO4 Ceramic material and preparation method thereof, belong to thermal barrier coating ceramic material technical field.The application is generated by pre-sintering preferentially even RETaO4 Powder, combined secondary ball milling makes powder particle more even refinement;Compared with only dry pressing forming, green density can be increased by 10-15 percentage points by cold isostatic pressing, and the final ceramic relative density is greater than or equal to 95%.The rare earth tantalate ceramic material of the application has low thermal conductivity, matched thermal expansion coefficient, low oxygen ion conductivity and wide temperature range CMAS corrosion resistance, can meet the harsh requirements of new generation high thrust-to-weight ratio aero-engine on environmental barrier coating material, has important engineering application value and industrialization prospect.

Description

Technical Field

[0001] This invention belongs to the field of anti-corrosion ceramic materials technology, specifically relating to a high-density, high-temperature resistant, and corrosion-resistant rare earth tantalate ceramic material and its preparation method. Background Technology

[0002] The continuous improvement in aero-engine performance is directly reflected in breakthroughs in core indicators such as thrust-to-weight ratio and flight time, which largely depend on the surge in turbine inlet temperature. This leads to critical hot-section components of the engine, especially turbine blades made of high-temperature alloys, operating at temperatures approaching or even exceeding the melting points of the materials themselves, posing a severe challenge to the limits of existing material systems. Against this backdrop, thermal barrier coatings have evolved from an auxiliary technology into an indispensable core technology for ensuring the safe and reliable operation of high thrust-to-weight ratio engines. Thermal barrier coatings are thin layers, typically composed of ceramic materials, successfully applied to the surfaces of hot-section engine components. Their core function is to utilize the excellent thermal insulation properties of ceramic materials to establish a physical barrier between the high-temperature combustion gases and the metal substrate, enabling the substrate alloy to operate stably in harsh environments far exceeding its own temperature limits, thus providing a crucial guarantee for achieving higher engine efficiency.

[0003] Currently, the most widely used and technologically mature thermal barrier coating material in engineering applications is 7-8 wt.% yttrium oxide-stabilized zirconium oxide. The success of YSZ is attributed to its excellent balance of comprehensive properties: its fracture toughness at room temperature can reach 3-5 MPa·m¹. / ², enabling it to withstand certain mechanical impacts and stresses; its coefficient of thermal expansion (~10⁻¹¹ × 10⁻¹²) -6 K -1 (room temperature to 1000℃) and nickel-based superalloy matrix (~14-16 × 10⁻⁶) -6 K -1 The relative matching helps reduce interfacial stress during thermal cycling; at the same time, its low thermal conductivity (typically below 2.5 W·m for bulk materials at 1000°C) helps reduce interfacial stress. -1 ·K -1This ensures effective basic thermal insulation. However, the YSZ system has a key inherent defect that limits its application prospects in next-generation engines—insufficient high-temperature phase stability. When the long-term operating temperature exceeds 1200°C, the metastable non-equilibrium tetragonal phase (t′ phase, Y₂O₃ supersaturated) in YSZ undergoes Y₂O₃ decomposition, transforming into a lower yttrium content equilibrium tetragonal phase (t phase) and a higher yttrium content cubic phase (c phase). Even more detrimental is that during subsequent cooling, the metastable t phase further transforms into a highly crack-sensitive monoclinic phase (m phase). This t→m phase transformation is typically accompanied by approximately 3-5% volume expansion, generating significant internal stress within the coating. This is a major cause of cracking, warping, and eventual peeling failure during thermal cycling. Therefore, the upper limit of the long-term operating temperature of YSZ is insufficient to meet the requirements of next-generation high thrust-to-weight ratio engines. Meanwhile, in higher-temperature service environments, calcium magnesium aluminum silicate (CMAS) corrosion, formed by the melting of environmental deposits such as inhaled dust and volcanic ash at high temperatures, has become another key factor leading to premature failure of advanced thermal barrier coatings. CMAS melts into a glassy substance with extremely low viscosity at temperatures of approximately 1200–1400°C. The molten CMAS glass has extremely low viscosity and good wettability, enabling it to rapidly wet and penetrate into the micron-sized pores and crack networks of typical plasma-sprayed thermal barrier coatings through capillary forces. On the one hand, the filling capacity of CMAS (its thermal conductivity is approximately 1.0–1.5 W·m) is limited. -1 ·K -1 It will significantly replace the static air in the pores (thermal conductivity ~0.03 W·m). -1 ·K -1 This drastically increases the effective thermal conductivity of the coating, reducing its insulation effect and leading to a runaway increase in substrate temperature, i.e., "thermal runaway." On the other hand, during the cooling process, the infiltrated CMAS glass solidifies and undergoes complex chemical reactions with the coating material, generating new phases. Simultaneously, due to the significant difference in thermal expansion coefficients between CMAS and the coating material, enormous thermal stress is generated, leading to blistering, cracking, and peeling of the coating. Currently, thermal barrier / environmental barrier coatings have evolved into an integrated protection system. Thermal barrier coatings are mainly deposited on the surface of high-temperature alloys, providing core insulation functions. Combined with internal cooling technology, they can significantly reduce substrate temperature. Environmental barrier coatings were initially developed primarily to protect SiC and other ceramic matrix composites from the volatile corrosion of high-temperature water and oxygen vapors, and have also been proven to effectively block the erosion of molten oxides such as CMAS. With the rapid development of materials science, many new-generation ceramic materials possess both good thermal insulation properties and excellent resistance to environmental corrosion, making the functional boundaries between traditionally defined thermal barrier coatings (focusing on insulation) and environmental barrier coatings (focusing on corrosion protection) increasingly blurred.

[0004] To overcome the temperature barrier and effectively inhibit CMAS corrosion, researchers worldwide have proposed various innovative solutions from two dimensions: new material design and surface engineering technology. These solutions aim to fundamentally improve the overall performance and lifespan of coatings in extreme environments. Among numerous candidate materials, rare earth tantalates (RETaO4) have attracted attention due to their potential high-temperature stability. However, current preparation methods for RETaO4 ceramics primarily employ conventional solid-state reaction methods. This process requires repeated calcination and grinding, is cumbersome, and easily introduces impurities, resulting in uneven powder particle size. Consequently, the sintered ceramics have low density (typically below 90%), and residual open holes and microcracks provide rapid penetration channels for CMAS melts, severely weakening the material's corrosion resistance. While hot pressing can improve density, its production cost is prohibitively high.

[0005] Therefore, the present invention aims to provide a low-cost preparation method for rare earth tantalate (RETaO4) ceramic materials that are highly dense, have uniform composition, and are resistant to CMAS corrosion over a wide temperature range. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a high-density, high-temperature resistant, and corrosion-resistant rare earth tantalate ceramic material and its preparation method.

[0007] The primary objective of this invention is achieved by providing a method for preparing a highly dense, high-temperature resistant, and corrosion-resistant rare-earth tantalate ceramic material, which is accomplished through the following steps: 1) Mix Ta2O5, Lu2O3, Yb2O3 and Tm2O3 oxide powders and then ball mill them to obtain mixed powder; the molar ratio of Ta2O5, Lu2O3, Yb2O3 and Tm2O3 is 3:1:1:1; 2) After drying the mixed powder at a constant temperature, sieve it, then pre-calcine it, grind the pre-calcineed powder and sieve it again; the drying temperature is 60-80℃ and the drying time is 12-24h. 3) The pre-calcined powder after sieving is ball-milled a second time and dried at a constant temperature. After drying, it is sieved a second time to obtain a mixed powder. 4) The mixed powder is pressed into tablets and then subjected to cold isostatic pressing, followed by high-temperature calcination to obtain a dense rare-earth tantalate ceramic material with the chemical formula (Lu). 1 / 3 Yb 1 / 3 Tm 1 / 3 )TaO4.

[0008] The second objective of this invention is achieved by providing a rare-earth tantalate ceramic material prepared based on the method, the chemical composition of which is (Lu... 1 / 3 Yb 1 / 3 Tm 1 / 3 TaO4 has a monoclinic phase structure and a density ≥95%.

[0009] This invention utilizes pre-firing to preferentially generate uniformly reacted RETaO4 powder, combined with secondary ball milling to further refine and homogenize the powder particles. Compared to dry pressing alone, cold isostatic pressing increases the green body density by 10-15 percentage points, resulting in a final ceramic relative density ≥95%. The chemical inertness of small ionic radius rare earth elements (Lu, Yb, Tm) synergistically works with the high-density (≥95%) process of this invention (pre-firing + secondary ball milling + cold isostatic pressing + high-temperature sintering) to ensure that RETaO4 ceramics exhibit near-zero resistance to CMAS corrosion reaction at 1350~1700℃.

[0010] The beneficial effects of this invention are as follows: 1. The rare earth tantalate ceramic material prepared by this invention has a coefficient of thermal expansion of 5.75 × 10⁻⁶ at high temperatures. -6 K -1 ), and the coefficient of thermal expansion of the matrix (silicon-based 5~6×10 ohms). -6 K -1 The closer the coefficients of thermal expansion, the less the coating cracks and peels due to mismatched coefficients of thermal expansion.

[0011] 2. The rare earth tantalate ceramic material prepared by this invention has an oxygen ion conductivity of 0.17~3.15×10⁻⁶ at high temperatures of 600-900°C. -5 S·cm -1 This is far lower than the oxygen ion conductivity (0.001~0.1 S·cm) of YSZ at this temperature. -1 The lower electrical conductivity means lower oxygen ion transport and higher oxygen insulation, which can effectively suppress the excessive growth of thermally grown oxides (TGO), help inhibit TGO growth, and reduce the chance of coating peeling off from TGO.

[0012] 3. The rare earth tantalate ceramic material prepared by this invention has a thermal conductivity of only 2.05 W·m at a high temperature of 900℃. -1 ·K -1 Excellent thermal insulation performance can effectively reduce the working temperature of the substrate, thereby extending the service life of heat-end components and improving service efficiency.

[0013] 4. The rare earth tantalate ceramic material prepared by this invention has near-zero resistance to CMAS corrosion reaction at 1350~1700℃.

[0014] In summary, the rare earth tantalate ceramic material of this invention combines low thermal conductivity, a matched coefficient of thermal expansion, low oxygen ion conductivity, and wide-temperature-range resistance to CMAS corrosion. It can meet the stringent requirements of next-generation high thrust-to-weight ratio aero-engines for environmental barrier coating materials, and has significant engineering application value and industrialization prospects. Attached Figure Description

[0015] Figure 1 This is a flowchart of the preparation method of the rare earth tantalate ceramic material of the present invention; Figure 2 The following are the performance characterization results of the rare earth tantalate ceramic material prepared in Example 1 of the present invention; wherein, (a) is the XRD pattern; (b) is the surface morphology diagram; and (c) is the elemental distribution diagram of electron dispersive energy dispersive spectroscopy (EDS). Figure 3 The images show the XRD patterns of the rare earth tantalate ceramic material prepared in Example 1 of this invention after CMAS etching at different temperatures and times. Figure 4 The image shows the EDS elemental distribution of the rare earth tantalate ceramic material prepared in Example 1 of this invention after CMAS corrosion at different temperatures and times. The backscattered phase shows no contrast change and the CMAS elements do not diffuse significantly into the substrate.

[0016] Figure 5 (Tm) prepared in Example 1 of this invention 1 / 3 Yb 1 / 3 Lu 1 / 3 Thermophysical and electrochemical properties of TaO4 ceramic materials; where (a) is the curve of thermal conductivity as a function of temperature, (b) is the curve of thermal expansion coefficient as a function of temperature, and (c) is the curve of oxygen ion conductivity as a function of temperature. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but this does not limit the present invention in any way. Any modifications or improvements made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0018] This invention discloses a method for preparing a high-density, high-temperature resistant, and corrosion-resistant rare-earth tantalate ceramic material, which is achieved through the following steps: 1) Mix Ta2O5 with Lu2O3, Yb2O3 and Tm2O3 oxide powders and then ball mill to obtain mixed powder; the molar ratio of Ta2O5, Lu2O3, Yb2O3 and Tm2O3 is 3:1:1:1, that is, the molar ratio of Ta to total rare earth elements is 1:1; 2) After drying the mixed powder at a constant temperature, sieve it, then pre-calcine it, grind the pre-calcineed powder and sieve it again; the drying temperature is 60-80℃ and the drying time is 12-24h. 3) The pre-calcined powder after sieving is ball-milled a second time and dried at a constant temperature. After drying, it is sieved a second time to obtain a mixed powder. 4) The mixed powder is pressed into tablets and then subjected to cold isostatic pressing, followed by high-temperature calcination to obtain a dense rare-earth tantalate ceramic material with the chemical composition (Lu). 1 / 3 Yb 1 / 3 Tm1 / 3 )TaO4.

[0019] In step 1), the ball mill speed is 200-500 r / min. During the ball milling process, the forward and reverse rotations alternate without interruption. The forward and reverse rotation times are both 15-30 min, and the total ball milling time is 12-24 h.

[0020] In step 2), the pre-firing process is as follows: the temperature is raised from room temperature to 1600℃, and pre-fired at 1600℃ for 4 hours; The heating program during the preheating process is as follows: the heating rate is 8-12℃ / min for 50-1000℃, 4-8℃ / min for 1000-1400℃, and 2℃ / min for 1400-1600℃; during the heating process, the temperature is held at 1000℃ for 10-30min, at 1200℃ for 10-30min, and at 1400℃ for 20-30min.

[0021] In step 2), the grinding time is 5-10 minutes, and the sieve mesh size is 100-300 mesh.

[0022] In step 3), the secondary ball milling speed is 200-400 r / min. During the ball milling process, the ball milling process alternates between forward and reverse rotation without interruption. The forward and reverse rotation times are both 15-30 minutes. The total time for the second ball milling is 6-12 hours, and the second sieve mesh size is 200-400 mesh.

[0023] In step 4), the high-temperature calcination process is as follows: the temperature is raised from room temperature to 1700℃ according to the following heating procedure, and then held at 1700℃ for 4-8 hours; The heating program is as follows: the heating rate is 8-12℃ / min for 50-1000℃, 4-8℃ / min for 1000-1400℃, and 2℃ / min for 1400℃-1700℃; during the heating process, the temperature is held at 1000℃ for 10-30 min, at 1200℃ for 10-30 min, and at 1400℃ for 20-30 min.

[0024] In step 4), cold isostatic pressing is performed by holding the pressure at 600-800MPa for 1-5 minutes.

[0025] This invention further provides a rare earth tantalate ceramic material prepared based on the method, the chemical composition of which is (Lu 1 / 3 Yb 1 / 3 Tm 1 / 3 TaO4 has a monoclinic phase structure and a density ≥95%.

[0026] Example 1 A method for preparing a high-density, high-temperature resistant, and corrosion-resistant rare-earth tantalate RETaO4 ceramic material includes the following steps: S1. Place the raw materials Ta2O5, Yb2O3, Lu2O3 and Tm2O3 powders into a drying oven and dry them at a constant temperature of 70℃ for 18 hours to remove trace amounts of moisture and other impurities adsorbed from the air, ensuring the purity of the raw materials and facilitating accurate proportioning in the later stages. S2. Weigh 5.295g of Ta2O5, 1.574g of Yb2O3, 1.589g of Lu2O3 and 1.541g of Tm2O3 respectively, and ball mill them at 400r / min for 16h with anhydrous ethanol as the dispersant to obtain a mixed powder. The alternation time between forward and reverse rotation is 20min, and there is no interruption when switching.

[0027] S3. Place the mixed powder in an 80℃ drying oven and dry at a constant temperature for 24 hours. After drying, pass it through a 300-mesh sieve. Place the sieved powder in a ceramic boat and pre-fire it in a muffle furnace at 1600℃ for 4 hours. The heating rate of the muffle furnace is 10℃ / min for 50-1000℃, 6℃ / min for 1000-1400℃, and 2℃ / min for 1400℃-1600℃. Hold at 1000℃ for 25 minutes, at 1200℃ for 25 minutes, and at 1400℃ for 25 minutes.

[0028] S4. Grind the pre-calcined powder for 5-10 minutes and then pass it through a 200-mesh sieve. Then, ball mill the sieved powder again for 8 hours at a speed of 300 r / min, a forward and reverse rotation time of 25 minutes, and 0 dwell time. Place the mixed powder in a drying oven for constant temperature drying at 70℃ for 20 hours. After drying, pass it through a 300-mesh sieve again.

[0029] S5. Weigh an appropriate amount of sieved powder and place it in the tableting mold. Press the mold at 10MPa for 2 minutes. Then press the tablets at 800MPa for 4 minutes using a cold isostatic press.

[0030] S6. The cold isostatically pressed green body is sintered in a muffle furnace at 1700℃ for 4 hours to obtain ceramic material. The heating rate is 10℃ / min for 50-1000℃, 6℃ / min for 1000-1400℃, and 2℃ / min for 1400-1700℃. The holding time is 25min at 1000℃, 25min at 1200℃, and 25min at 1400℃.

[0031] The phase composition, morphology, and elemental distribution of the ceramic material were analyzed using XRD and SEM. Figure 2(a) It can be seen that the peak positions and peak intensities of the experimental XRD pattern and the theoretical LuTaO4 pattern in the ICDD / JCPDS card library match well, indicating that the synthesized powder is a pure phase and only the monoclinic phase is detected, indicating that a solid solution (Tm) has been synthesized. 1 / 3 Yb 1 / 3 Lu 1 / 3 TaO4. (e.g.) Figure 2 As shown in (b), significant secondary recrystallization occurred in the observed area, forming abnormally large grains up to tens of micrometers in size, with a small number of cracks but no obvious pores, indicating high density. Furthermore, through... Figure 2 (c) It can be observed that all elements are uniformly distributed within the grains, further confirming the formation of (Tm) 1 / 3 Yb 1 / 3 Lu 1 / 3 It is a single-phase solid solution of TaO4. Finally, the density of the ceramic was measured to be above 95% by Archimedes' displacement method.

[0032] Test Example 1: Resistance to CMAS corrosion of RETaO4 ceramic material prepared in Example 1 Detection method: S1. Take the smooth and flat ceramic discs prepared in Example 1, clean them with anhydrous ethanol using ultrasonic cleaning and dry them, and divide them into 4 groups: 1350℃ group, 1500℃ group, 1600℃ group and 1700℃ group.

[0033] S2, CMAS preparation: Weigh out 39.2% CaO, 5.2% MgO, 4.1% Al2O3 and 51.5% SiO2 by mass percentage, use anhydrous ethanol as dispersant, place in a ball mill jar and ball mill for 16 hours at a speed of 400 r / min, a forward and reverse rotation time of 20 min and 0 dwell time.

[0034] S3. Drying and sieving: The ball-milled slurry is placed in a vacuum drying oven and dried at 80°C for 24 hours to remove ethanol and obtain a mixed powder; the powder is then passed through a 200-mesh sieve to obtain CMAS powder with uniform particle size.

[0035] S4. CMAS Coating and High-Temperature Corrosion: CMAS powder was mixed with ethanol at a mass ratio of 1:2 to prepare a suspension, which was then uniformly coated onto the surface of the ceramic discs prepared in Example 1, with a coating amount of 20–35 mg / cm². 2 Drying was performed to allow the ethanol to evaporate. Then, the samples coated with CMAS were placed in a muffle furnace and heated to 1350℃, 1500℃, 1600℃, and 1700℃, respectively. Group 1350℃: 50-1000℃, heating rate is 10℃ / min; 1000-1350℃, heating rate is 6℃ / min, of which 1000℃ is held for 25min, 1200℃ is held for 25min, and 1350℃ is held for 5h, 20h or 50h, and then cooled with the furnace.

[0036] Group 1500℃: 50-1000℃, heating rate is 10℃ / min; 1000-1400℃, heating rate is 6℃ / min; 1400℃-1500℃, heating rate is 2℃ / min; wherein, hold at 1000℃ for 25min, hold at 1200℃ for 25min, hold at 1400℃ for 25min, hold at 1500℃ for 5h, and then cool with the furnace.

[0037] Group 1600℃: 50-1000℃, heating rate is 10℃ / min; 1000-1400℃, heating rate is 6℃ / min; 1400℃-1600℃, heating rate is 2℃ / min; wherein, hold at 1000℃ for 25min, hold at 1200℃ for 25min, hold at 1400℃ for 25min, hold at 1600℃ for 5h, and then cool with the furnace.

[0038] Group 1700℃: 50-1000℃, heating rate is 10℃ / min; 1000-1400℃, heating rate is 6℃ / min; 1400℃-1700℃, heating rate is 2℃ / min; wherein, hold at 1000℃ for 25min, hold at 1200℃ for 25min, hold at 1400℃ for 25min, hold at 1700℃ for 5h, and then cool with the furnace.

[0039] S5. Performance characterization: After corrosion, the phase change of the sample was tested by XRD and the cross section was observed by scanning electron microscopy (SEM).

[0040] Results analysis: such as Figure 3-4 As shown, the ceramic material prepared in Example 1 showed no corrosion reaction layer after etching at 1350℃ for 5h, 20h, and 50h, respectively, and XRD analysis also revealed no new phase formation. Similarly, after etching at 1500℃, 1600℃, and 1700℃ for 5 hours, no obvious corrosion reaction layer was observed, no new phase formation was detected, the backscattered phase showed no contrast change, and EDS analysis showed that the major elements in the CMAS did not diffuse significantly into the substrate. These results indicate that the ceramic material (Tm) prepared in this invention... 1 / 3 Yb 1 / 3Lu 1 / 3 TaO4 exhibits excellent resistance to CMAS corrosion within a temperature range of 1350–1700℃ and under corrosion conditions lasting up to 50 hours.

[0041] Test Example 2: Thermophysical and electrochemical properties of RETaO4 ceramic material prepared in Example 1 S1. Take the smooth and flat ceramic disc prepared in Example 1, clean it ultrasonically with anhydrous ethanol and dry it. Grind it to prepare a disc sample with a diameter of 6 mm and a thickness of 1.2 mm for testing thermal conductivity; similarly, use diamond wire cutting to cut cuboid samples with length, width and height of 12.0, 3.0 and 1.2 mm respectively for testing thermal expansion coefficient; take a disc with a diameter of 12.7 mm and polish it, coat both sides of the sample with silver paste, sinter it at 800℃, and use it for oxygen ion conductivity testing.

[0042] S2. Thermal conductivity test: The thermal conductivity of the samples was tested using a Netzsch LFA457 thermal conductivity meter (Germany). Before testing, both sides of the samples were carbonized. Test points were set at 25℃ and every 100℃ within the 100℃~900℃ range, with three data points collected at each temperature point, and the average value was taken.

[0043] Result: As Figure 5 As shown in (a), the thermal conductivity of the sample decreases significantly and tends to plateau as the temperature rises to 900℃, with a thermal conductivity of only 2.05 W·m at 900℃. -1 ·K -1 .

[0044] S3. Thermal expansion coefficient test: The thermal expansion coefficient is tested using a dilatometer (Germany Netzsch DIL402), with a test temperature range from room temperature to 1200℃.

[0045] Result: As Figure 5 As shown in (b), the coefficient of thermal expansion of the sample at the highest test temperature of 1200℃ is approximately 5.75 × 10⁻⁶. -6 K -1 This value is similar to the coefficient of thermal expansion of silicon-based substrates such as traditional silicon carbide-based composites (typically between 4.0 and 5.5 × 10⁻⁶). -6 K -1 The properties (between) are very close, indicating good thermal compatibility. This demonstrates that the ceramic material can effectively reduce shear stress caused by thermal mismatch during high-temperature cyclic service, preliminarily confirming its potential as a surface material for novel environmental barrier coatings (EBCs).

[0046] S4. Oxygen Ion Conductivity Test: The AC impedance of the ceramic sample was measured using an SP-300 BioLogic AC impedance spectrometer. The test conditions were: voltage range ±10V, frequency range 1.0Hz~2MHz, and test temperature 600℃~900℃, with tests performed every 50℃. The total resistance of the ceramic sample was obtained by fitting the impedance spectra at each temperature, and the oxygen ion conductivity was calculated.

[0047] Results: As shown in Figure 5(c), the conductivity of the sample increases with increasing temperature, exhibiting typical thermally activated semiconductor conductivity characteristics. At the lowest test temperature of 600℃, the conductivity is only 0.17×10⁻⁶. -5 S·cm -1 Even at a high temperature of 900℃, the conductivity only increased to 3.15×10⁻⁶. -5 S·cm -1 Such low high-temperature conductivity indicates that the ceramic material prepared in Example 1 has excellent oxygen barrier properties, which can effectively inhibit the diffusion of oxygen ions into the internal substrate under high-temperature conditions, thereby delaying the growth of thermally generated oxide (TGO) layers.

[0048] In summary, this invention successfully prepared a highly dense, single-phase rare-earth tantalate (RETaO4) ceramic material by combining a simple solid-state reaction method with cold isostatic pressing and high-temperature sintering. This material exhibits a coefficient of thermal expansion matching that of a silicon-based matrix, extremely low oxygen ion conductivity and thermal conductivity, and demonstrates excellent chemical inertness and impermeability to CMAS melts over a wide temperature range of 1350℃ to 1700℃. The preparation method provided by this invention is simple and reproducible, and the prepared ceramic material has broad application prospects in high-temperature protection fields such as thermal barrier coatings for aero-engines and environmental barrier coatings.

[0049] The specific embodiments of the present invention have been described in detail above, but these are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the invention are also within the scope of the present invention. Therefore, all equivalent transformations, modifications, and improvements made without departing from the spirit and principles of the present invention should be covered within the scope of the present invention.

Claims

1. A method for preparing a high-density, high-temperature resistant, and corrosion-resistant rare-earth tantalate ceramic material, characterized in that, Follow these steps to achieve the following: 1) Mix Ta2O5 with Lu2O3, Yb2O3 and Tm2O3 oxide powders and then ball mill to obtain mixed powder; the molar ratio of Ta2O5, Lu2O3, Yb2O3 and Tm2O3 is 3:1:1:1, that is, the molar ratio of Ta to total rare earth elements is 1:1; 2) After drying the mixed powder at a constant temperature, sieve it, then pre-calcine it, grind the pre-calcineed powder and sieve it again; the drying temperature is 60-80℃ and the drying time is 12-24h. 3) The pre-calcined powder after sieving is ball-milled a second time and dried at a constant temperature. After drying, it is sieved a second time to obtain a mixed powder. 4) The mixed powder is pressed into tablets and then subjected to cold isostatic pressing, followed by high-temperature calcination to obtain a dense rare-earth tantalate ceramic material with the chemical composition (Lu). 1 / 3 Yb 1 / 3 Tm 1 / 3 )TaO4.

2. The preparation method according to claim 1, characterized in that, In step 1), the ball mill speed is 200-500 r / min. During the ball milling process, the forward and reverse rotations alternate without interruption. The forward and reverse rotation times are both 15-30 min, and the total ball milling time is 12-24 h.

3. The preparation method according to claim 1, characterized in that, In step 2), the pre-firing process is as follows: the temperature is raised from room temperature to 1600℃, and pre-fired at 1600℃ for 4 hours; The heating program during the preheating process is as follows: the heating rate is 8-12℃ / min for 50-1000℃, 4-8℃ / min for 1000-1400℃, and 2℃ / min for 1400-1600℃; during the heating process, the temperature is held at 1000℃ for 10-30min, at 1200℃ for 10-30min, and at 1400℃ for 20-30min.

4. The preparation method according to claim 1, characterized in that, In step 2), the grinding time is 5-10 minutes, and the sieve mesh size is 100-300 mesh.

5. The preparation method according to claim 1, characterized in that, In step 3), the secondary ball milling speed is 200-400 r / min. During the ball milling process, the ball milling process alternates between forward and reverse rotation without interruption. The forward and reverse rotation times are both 15-30 minutes. The total time for the second ball milling is 6-12 hours, and the second sieve mesh size is 200-400 mesh.

6. The preparation method according to claim 1, characterized in that, In step 4), the high-temperature calcination process is as follows: the temperature is raised from room temperature to 1700℃ according to the following heating procedure, and then held at 1700℃ for 4-8 hours; The heating program is as follows: the heating rate is 8-12℃ / min for 50-1000℃, 4-8℃ / min for 1000-1400℃, and 2℃ / min for 1400℃-1700℃; during the heating process, the temperature is held at 1000℃ for 10-30 min, at 1200℃ for 10-30 min, and at 1400℃ for 20-30 min.

7. The preparation method according to claim 1, characterized in that, In step 4), cold isostatic pressing is performed by holding the pressure at 600-800MPa for 1-5 minutes.

8. A rare earth tantalate ceramic material prepared according to the method of any one of claims 1 to 7, characterized in that, The chemical composition of the rare earth tantalate ceramic material is (Lu 1 / 3 Yb 1 / 3 Tm 1 / 3 TaO4 has a monoclinic phase structure and a density ≥95%.

Images