Light / heavy rare earth combined high-entropy rare earth aluminate and application of thermal barrier coating thereof

Abstract

The invention discloses a high-entropy rare earth aluminate based on light / heavy rare earth combination, the chemical formula of the high-entropy rare earth aluminate meets RE4Al2O9, RE is a rare earth element combination and is composed of a light rare earth element and three heavy rare earth elements, the number of the rare earth elements is four, and the substance amount ratio of the light rare earth element to the three heavy rare earth elements is 1: 1: 1: 1; the material is of a single-phase structure and has high-temperature stability. The preparation method comprises the following steps: firstly, carrying out solid-phase sintering, and then carrying out ball milling and sieving. When the material is used as a thermal barrier coating material, hot pressed sintering is carried out, and the Young modulus of 180-210 GPa, the shear modulus of 70-90 GPa, the bulk modulus of 130-150 GPa, the Vickers hardness of 9.1-9.2 GPa, the bending strength of 190-220 MPa and the fracture toughness of 2.9-3.2 MPa.m < 1 / 2 > are obtained. The thermal conductivity is 1.61-1.87 W.m <-1 >. K <-1 > in the temperature range of 25-1000 DEG C, and the thermal conductivity is 2.07-2.22 W.m <-1 >. K <-1 > at the high temperature of 1200 DEG C.

Description

Technical Field

[0001] This invention relates to the field of thermal barrier coating technology, and in particular to the application of a thermal barrier coating based on a combination of light / heavy rare earth high-entropy rare earth aluminates. Background Technology

[0002] The application of thermal barrier coatings is to provide thermal protection for the high-temperature core components of aero engines. Therefore, the materials of thermal barrier coatings need to meet the requirements of high melting point, high high-temperature phase stability, low thermal conductivity and good mechanical properties.

[0003] Currently, the commercially available thermal barrier coating material is 7-8 wt.% yttria-stabilized zirconia (YSZ), with a thermal conductivity of 2-3 W·m. -1 ·K -1 However, this thermal barrier coating material suffers from a technical problem: phase transitions at high temperatures lead to material degradation. For example, existing literature 1 (Clarke DR, Oechsner M, Padture NP, et al. Thermal-barrier coatings for more efficient gas-turbine engines[J]. MRS Bulletin, 2012, 37: 891-898.) clearly points out that when the service temperature exceeds 1200℃, YSZ exhibits a phase transition from a metastable tetragonal phase to a monoclinic phase. Furthermore, the phase transition is accompanied by rapid densification, ultimately leading to cracking and failure of the thermal barrier coating, i.e., a technical problem of poor high-temperature phase stability.

[0004] Besides YSZ materials, rare earth aluminates have low Young's modulus and a coefficient of thermal expansion close to that of silicon-based ceramic matrix composites, making them suitable as thermal barrier coating materials. Furthermore, rare earth aluminates do not suffer from the poor high-temperature phase stability of YSZ materials. For example, existing literature 2 (Yamane H, Omori Mamoru, Okubo A, et al. High-Temperature Phase Transition of Y4Al2O9[J]. Journal of the American Ceramic Society, 1993, 76(9): 2382-2384) shows that Y4Al2O9 exhibits high-temperature stability below 1300℃. However, according to existing literature 3 (Xiang H, Feng Z, Li Z, et al. Crystal structure, mechanical and thermal properties of Yb4Al2O9: A combination of experimental and theoretical investigations[J]. Journal of the European Ceramic Society, 2017, 37(6):2491-2499.), the thermal conductivity of Y4Al2O9 at room temperature is 3.25 W·m. -1 ·K -1 It is significantly higher than commercial YSZ and cannot meet the performance requirements for thermal insulation. Summary of the Invention

[0005] The purpose of this invention is to provide an application of high-entropy rare-earth aluminates based on a combination of light and heavy rare-earth elements and their thermal barrier coatings. To achieve this objective, the principle of this invention is that, since the disorder of the A-site ion radius in high-entropy ceramics is negatively correlated with thermal conductivity, adjusting the combination of light and heavy rare-earth elements increases the disorder of the ion radius, thereby enhancing phonon scattering, shortening the phonon mean free path, and ultimately reducing thermal conductivity.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] A high-entropy rare earth aluminate based on a combination of light and heavy rare earth elements, with the chemical formula RE4Al2O9, where RE represents a combination of rare earth elements, and there are four types of rare earth elements in a molar ratio of 1:1:1:1.

[0008] The rare earth element combination consists of one light rare earth element and three heavy rare earth elements, i.e., a light / heavy rare earth combination.

[0009] The light rare earth element is one of La, Nd, Sm and Eu; the heavy rare earth element is three of Gd, Dy, Ho, Er, Yb and Lu.

[0010] Based on the single-phase structure of light / heavy rare earth combined high-entropy rare earth aluminate, it exhibits high-temperature stability in the temperature range of 20-1250℃.

[0011] A method for preparing high-entropy rare earth aluminates based on a combination of light and heavy rare earth elements includes the following steps: using light rare earth oxides, heavy rare earth oxides, and Al2O3 as raw materials, firstly, the light rare earth oxides are pre-sintered; then, to satisfy the molar ratio of each element in the chemical formula, the light rare earth oxides, heavy rare earth oxides, and Al2O3 are ball-milled for the first time to obtain a first ball-milled product; after ball milling, the first ball-milled product is washed and dried; then, the first ball-milled product is sintered for the first time to obtain a first sintered product; after completing the first ball milling and the first sintering, ball milling is repeated under the same conditions, i.e., a second ball milling is performed, and the second ball-milled product is sieved with a sieve mesh size of 200 to obtain high-entropy rare earth aluminates based on a combination of light and heavy rare earth elements.

[0012] The washing conditions are as follows: the washing solvent is anhydrous ethanol, the washing number is 5 times, and the drying conditions are as follows: the drying temperature is 80℃, and the drying time is 12 h.

[0013] The light rare earth oxide is Sm2O3, and the heavy rare earth oxide is Gd2O3, Er2O3, and Yb2O3; the chemical formula is RE4Al2O9, where RE represents rare earth elements.

[0014] The pre-sintering conditions are: a pre-sintering temperature of 1300℃ and a pre-sintering time of 1 h.

[0015] The ball milling conditions are as follows: the ball milling speed is 250 rpm, the ball milling medium is anhydrous ethanol, the material of the grinding balls is zirconium oxide, the total ball milling time is 24 h, and the ball milling time is paused for 30 min when it reaches 6 h.

[0016] The sintering conditions are: sintering temperature of 1600℃ and sintering time of 4 h.

[0017] When using light / heavy rare earth combined high-entropy rare earth aluminate as a thermal barrier coating material, the light / heavy rare earth combined high-entropy rare earth aluminate is hot-pressed and sintered under argon and pressurized conditions, that is, a heating process and a cooling process are carried out to obtain blocky light / heavy rare earth combined high-entropy rare earth aluminate.

[0018] In the conditions of hot pressing and sintering,

[0019] The pressurization conditions are: pressurization temperature of 800℃ and pressurization pressure of 30 MPa;

[0020] The heating process is a two-stage heating process. The first stage heating rate is 10℃ / min, and the target temperature for the first stage is 1000℃. The second stage heating rate is 8℃ / min, and the target temperature for the second stage is 1750℃. The holding time for the second stage is 1 hour. The cooling process is a two-stage cooling process. The first stage cooling rate is 10℃ / min, and the target temperature for the first stage is 1000℃. The second stage cooling is furnace cooling.

[0021] The obtained high-entropy rare-earth aluminates based on light / heavy rare-earth composites exhibit a Young's modulus of 180-210 GPa, a shear modulus of 70-90 GPa, a bulk modulus of 130-150 GPa, a Vickers hardness of 9.1-9.2 GPa, a flexural strength of 190-220 MPa, and a fracture toughness of 2.9-3.2 MPa·m. 1 / 2 Its thermal conductivity is 1.61-1.87 W·m in the temperature range of 25-1000℃. -1 ·K -1 Furthermore, at a high temperature of 1200℃, the thermal conductivity is 2.07-2.22 W·m. -1 ·K -1 .

[0022] The technical effects of this invention have been tested experimentally, and the specific details are as follows:

[0023] XRD test results indicate that the high-entropy rare earth aluminate based on the light / heavy rare earth combination has a single-phase structure.

[0024] DSC test results show that high-entropy rare earth aluminates based on light / heavy rare earth combinations have high-temperature stability.

[0025] SEM-EDS test results show that all elements in the high-entropy rare earth aluminate based on the light / heavy rare earth combination exhibit uniform and continuous distribution characteristics. At the same time, the atomic content of each element ranges from 8.93 to 9.75 at.%, which is consistent with the stoichiometric ratio.

[0026] Mechanical property test results show that the Young's modulus of the light / heavy rare earth composite high-entropy rare earth aluminate is 180-210 GPa, the shear modulus is 70-90 GPa, the bulk modulus is 130-150 GPa, the Vickers hardness is 9.1-9.2 GPa, the flexural strength is 190-220 MPa, and the fracture toughness is 2.9-3.2 MPa·m. 1 / 2 .

[0027] Thermal performance test results show that the thermal conductivity of high-entropy rare-earth aluminates based on light / heavy rare-earth composites first decreases and then increases with increasing temperature, with a thermal conductivity of 1.61-1.87 W·m in the temperature range of 25-1000℃. -1 ·K -1 Furthermore, at a high temperature of 1200℃, the thermal conductivity is 2.07-2.22 W·m. -1 ·K -1 .

[0028] Therefore, the present invention has the following advantages over the prior art:

[0029] 1. This invention prepares high-entropy rare earth aluminates with high-temperature phase stability by combining light and heavy rare earth elements.

[0030] 2. This invention increases the disorder of ionic radius by combining light and heavy rare earth elements, thereby enhancing phonon scattering, shortening the mean free path of phonons, and achieving the goal of reducing thermal conductivity. Attached Figure Description

[0031] Figure 1 The XRD patterns are of Example 1, Comparative Example 1, Comparative Example 2, Example 2, Comparative Example 3, and Comparative Example 4.

[0032] Figure 2 The DSC diagram for Example 1;

[0033] Figure 3 SEM-EDS images of Example 1, Comparative Example 1, Comparative Example 2 and Example 2;

[0034] Figure 4 The thermal diffusivity diagrams are for Example 1, Comparative Example 1, Comparative Example 2, and Example 2.

[0035] Figure 5 Specific heat capacity diagrams for Example 1, Comparative Example 1, Comparative Example 2, and Example 2;

[0036] Figure 6 Thermal conductivity diagrams for Example 1, Comparative Example 1, Comparative Example 2, and Example 2. Detailed Implementation

[0037] The present invention will be further described in detail through embodiments and with reference to the accompanying drawings, but this is not intended to limit the scope of the invention.

[0038] Example 1

[0039] A high-entropy rare earth aluminate based on a combination of light and heavy rare earth elements, with the chemical formula RE4Al2O9, wherein RE is a combination of rare earth elements, and the combination of rare earth elements meets the requirements of high-entropy ceramics, that is, there are four types of rare earth elements, and the molar ratio between each rare earth element is 1:1:1:1.

[0040] The rare earth combination consists of one light rare earth element and three heavy rare earth elements, namely light / heavy rare earth combination. For ease of distinction later, it is named Combination-(1:3) based on the ratio of light / heavy rare earth elements, or simply C-(1:3).

[0041] The light rare earth element is one of La, Nd, Sm and Eu; the heavy rare earth element is three of Gd, Dy, Ho, Er, Yb and Lu.

[0042] A method for preparing high-entropy rare earth aluminates based on a combination of light and heavy rare earth elements includes the following steps: ... (Sm... 0.25 Gd 0.25 Er 0.25 Yb 0.25 )4Al2O9 and Sm2O3 are light rare earth element raw materials, Gd2O3, Er2O3 and Yb2O3 are heavy rare earth element raw materials, and Al2O3 is an aluminum oxide raw material. First, under the conditions of a pre-sintering temperature of 1300℃ and a pre-sintering time of 1 h, the light rare earth element raw material Sm2O3 is pre-sintered to remove residual moisture and organic impurities. Then, to meet the molar ratio of each element in the chemical formula, under certain ball milling conditions, Sm2O3, Gd2O3, Er2O3, Yb2O3 and Al2O3 are ball milled for the first time to obtain the first ball milling product.

[0043] The ball milling conditions are as follows: the ball milling speed is 250 rpm, the ball milling medium is anhydrous ethanol, the material of the grinding balls is zirconium oxide, the total ball milling time is 24 h, and the ball milling time is paused for 30 min when it reaches 6 h.

[0044] After ball milling, the first ball milling product was washed and dried. Then, the first ball milling product was sintered for the first time at a sintering temperature of 1600℃ and a sintering time of 4 h to obtain the first sintered product.

[0045] The washing conditions are as follows: the washing solvent is anhydrous ethanol, the washing number is 5 times, and the drying conditions are as follows: the drying temperature is 80℃, and the drying time is 12 h.

[0046] After the first ball milling and first sintering, the ball milling was repeated under the same conditions, i.e., a second ball milling was performed. The product from the second ball milling was then sieved through a 200-mesh screen to obtain a high-entropy rare earth aluminate (Sm) based on a light / heavy rare earth combination. 0.25 Gd 0.25 Er 0.25 Yb 0.25 )4Al2O9, abbreviated as L(Sm)-H(GdErYb).

[0047] To demonstrate the single-phase structure of L(Sm)-H(GdErYb), XRD tests were performed. The test results are as follows: Figure 1 As shown, L(Sm)-H(GdErYb) is a single-phase structure, with no phase transition and no impurity phase generated.

[0048] To demonstrate the high-temperature stability of L(Sm)-H(GdErYb), DSC testing was performed. The test results are as follows: Figure 2 As shown, L(Sm)-H(GdErYb) did not undergo a phase transition or decomposition within a temperature range of 20-1250℃. The test results indicate that L(Sm)-H(GdErYb) possesses high-temperature stability.

[0049] In order to conduct subsequent microstructure, mechanical properties and thermal properties tests, L(Sm)-H(GdErYb) was hot-pressed and sintered.

[0050] The specific method of hot pressing sintering is to carry out hot pressing sintering under argon and pressurized conditions, that is, to carry out heating and cooling processes to obtain block L(Sm)-H(GdErYb);

[0051] The pressurization conditions are: pressurization temperature of 800℃ and pressurization pressure of 30 MPa;

[0052] The heating process is a two-stage heating process. The first stage heating rate is 10℃ / min, and the target temperature for the first stage is 1000℃. The second stage heating rate is 8℃ / min, and the target temperature for the second stage is 1750℃. The holding time for the second stage is 1 hour. The cooling process is a two-stage cooling process. The first stage cooling rate is 10℃ / min, and the target temperature for the first stage is 1000℃. The second stage cooling is furnace cooling.

[0053] Microscopic morphology testing, i.e., SEM-EDS test results, are as follows: Figure 3As shown, L(Sm)-H(GdErYb) contains Sm, Gd, Er, Yb, Al, and O elements, and each element exhibits a uniform and continuous distribution. The atomic contents of Sm, Gd, Er, and Yb are shown in Table 1, with the rare earth element atomic contents ranging from 8.98 to 9.10 at.%, consistent with stoichiometry. The test results indicate that L(Sm)-H(GdErYb) is a high-entropy ceramic.

[0054] Table 1 Summary of Atomic Content in High-Entropy Ceramics

[0055]

[0056] The mechanical property test results are shown in Table 2. The Young's modulus of L(Sm)-H(GdErYb) is 180.1 GPa, the shear modulus is 70.6 GPa, the bulk modulus is 133.7 GPa, the Vickers hardness is 9.11 GPa, the flexural strength is 190.27 MPa, and the fracture toughness is 2.9 MPa·m. 1 / 2 .

[0057] Table 2 Summary of Mechanical Properties of High-Entropy Ceramics

[0058]

[0059] Thermal performance testing includes density testing and thermal diffusivity testing.

[0060] The density was tested using Archimedes' displacement method, and the result showed that the density of L(Sm)-H(GdErYb) was 6.813 g / cm³. 3 .

[0061] The results of the thermal diffusivity test are shown in Table 3 and Figure 4 As shown, the thermal diffusivity of L(Sm)-H(GdErYb) first decreases and then increases with increasing temperature, reaching 0.636 mm at 1200℃. 2 / s.

[0062] Table 3 Summary of Thermal Performance Parameters of L(Sm)-H(GdErYb)

[0063]

[0064] Furthermore, the specific heat capacity was calculated according to the Neumann-Kopp law, and the calculation results are shown in Table 3 and... Figure 5 As shown, the specific heat capacity of L(Sm)-H(GdErYb) increases monotonically with increasing temperature, and is 0.512 J·g at 1200℃. -1 ·K -1 .

[0065] Thermal conductivity was then calculated using density, thermal diffusivity, and specific heat capacity. The results are shown in Table 3. Figure 6 As shown, the thermal conductivity of L(Sm)-H(GdErYb) first decreases and then increases with increasing temperature, reaching a minimum of 1.61 W·m at 600℃. -1 ·K -1 At a temperature of 1200℃, the thermal conductivity is 2.22 W·m. -1 ·K -1 .

[0066] To accurately quantify the effect of element selection in light / heavy rare earth combinations on thermal conductivity, the disorder of A-site ionic radii in L(Sm)-H(GdErYb) was calculated. The result shows that the disorder of A-site ionic radii in L(Sm)-H(GdErYb) is 3.95%.

[0067] To demonstrate the effect of light / heavy rare earth combinations on high-entropy rare earth aluminates, Comparative Examples 1, 2, 3, and 4 are provided, wherein...

[0068] The rare earth element combination in Comparative Example 1 is a combination of four heavy rare earth elements, namely C-(0:4);

[0069] The rare earth element combination in Comparative Example 2 is a combination of two light rare earth elements and two heavy rare earth elements, namely C-(2:2);

[0070] The rare earth element combination in Comparative Example 3 is a combination of three light rare earth elements and one heavy rare earth element, namely C-(3:1).

[0071] The rare earth element combination in Comparative Example 4 is a combination of four light rare earth elements, namely C-(4:0);

[0072] Meanwhile, Example 2 is provided, in which the combination of rare earth elements is the same as in Example 1, namely C-(1:3), but the light rare earth element is replaced by Nd instead of Sm.

[0073] Comparative Example 1

[0074] A method for preparing C-(0:4) is described, with the steps not specifically described being the same as in Example 1, except that C-(1:3) is replaced with C-(0:4), that is, the rare earth combination consisting of one light rare earth element and three heavy rare earth elements is replaced with a rare earth combination consisting of four heavy rare earth elements, specifically Gd, Ho, Er, and Lu, to obtain a high-entropy rare earth aluminate (Gd) based on the light / heavy rare earth combination. 0.25 Ho 0.25 Er 0.25 Lu 0.25)4Al2O9, abbreviated as H(GdHoErLu).

[0075] XRD test results are as follows Figure 1 As shown, H(GdHoErLu) is a single-phase structure, with no phase transition and no impurity phase generated.

[0076] Microscopic morphology test results are as follows Figure 3 As shown, H(GdHoErLu) contains Gd, Ho, Er, Lu, Al, and O elements, and each element exhibits a uniform and continuous distribution. The atomic contents of Gd, Ho, Er, and Lu are shown in Table 1, with the rare earth element atomic contents ranging from 8.77 to 9.80 at.%, consistent with stoichiometry. The test results indicate that H(GdHoErLu) is a high-entropy ceramic.

[0077] The mechanical property test results are shown in Table 2. The Young's modulus of H(GdHoErLu) is 205.5 GPa, the shear modulus is 81.5 GPa, the bulk modulus is 143.1 GPa, the Vickers hardness is 8.88 GPa, the flexural strength is 195.91 MPa, and the fracture toughness is 2.9 MPa·m. 1 / 2 Compared with the L(Sm)-H(GdErYb) obtained in Example 1, although there is no substantial difference in hardness, flexural strength, and fracture toughness, L(Sm)-H(GdErYb) has a lower modulus. The low modulus indicates that L(Sm)-H(GdErYb) can mitigate the effects of thermal stress concentration through its own deformation, i.e., it has the characteristic of being less prone to cracking, which can improve the service life of the thermal barrier coating.

[0078] The density test results show that the density of H(GdHoErLu) is 7.402 g / cm³. 3 .

[0079] The results of the thermal diffusivity test are shown in Table 4 and Figure 4 As shown, the thermal diffusivity of H(GdHoErLu) first decreases and then increases with increasing temperature, reaching 0.662 mm at 1200℃. 2 / s.

[0080] Table 4 Summary of Thermal Performance Parameters of H(GdHoErLu)

[0081]

[0082] The specific heat capacity calculation results are shown in Table 4 and Figure 5 As shown, the specific heat capacity of H(GdHoErLu) increases monotonically with increasing temperature, and at 1200℃, the specific heat capacity is 0.485 J·g. -1·K -1 .

[0083] The thermal conductivity calculation results are shown in Table 4 and Figure 6 As shown, the thermal conductivity of H(GdHoErLu) first decreases and then increases with increasing temperature, reaching a minimum value of 1.78 W·m at 400℃. -1 ·K -1 At a temperature of 1200℃, the thermal conductivity is 2.37 W·m. -1 ·K -1 Compared with L(Sm)-H(GdErYb) obtained in Example 1, it can be seen that using a C-(1:3) rare earth combination can reduce thermal conductivity.

[0084] The calculated disorder of the A-site ion radius of H(GdHoErLu) is 3.07%.

[0085] The calculation results of thermal conductivity and A-site ion radius disorder show that there is a negative correlation between A-site ion radius disorder and thermal conductivity. The basic principle is that increasing ion radius disorder can enhance phonon scattering, thereby shortening the phonon mean free path, which ultimately manifests as an improvement in thermal performance.

[0086] As can be seen from Example 1 and Comparative Example 1, the mechanical and thermal properties of the C-(1:3) rare earth combination are superior to those of C-(0:4).

[0087] Comparative Example 2

[0088] A method for preparing C-(2:2) is the same as in Example 1 unless otherwise specified, except that C-(1:3) is replaced with C-(2:2), that is, the rare earth combination consisting of one light rare earth element and three heavy rare earth elements is replaced with a rare earth combination consisting of two light rare earth elements and two heavy rare earth elements. Specifically, the two light rare earth elements are Sm and Eu, and the two heavy rare earth elements are Gd and Dy, to obtain a high-entropy rare earth aluminate (Sm) based on the light / heavy rare earth combination. 0.25 Eu 0.25 Gd 0.25 Dy 0.25 )4Al2O9, abbreviated as L(SmEu)-H(GdDy).

[0089] XRD test results are as follows Figure 1 As shown, L(SmEu)-H(GdDy) is a single-phase structure, with no phase transition and no impurity phase generated.

[0090] Microscopic morphology test results are as follows Figure 3As shown, L(SmEu)-H(GdDy) contains Sm, Eu, Gd, Dy, Al, and O elements, and each element exhibits a uniform and continuous distribution. The atomic contents of Sm, Eu, Gd, and Dy are shown in Table 1, with the rare earth element atomic contents ranging from 8.70 to 10.43 at.%, consistent with stoichiometry. The test results indicate that L(SmEu)-H(GdDy) is a high-entropy ceramic.

[0091] The mechanical property test results are shown in Table 2. The Young's modulus of L(SmEu)-H(GdDy) is 170.4 GPa, the shear modulus is 67.1 GPa, the bulk modulus is 123.3 GPa, the Vickers hardness is 7.72 GPa, the flexural strength is 170.85 MPa, and the fracture toughness is 2.5 MPa·m. 1 / 2 Compared with L(Sm)-H(GdErYb) obtained in Example 1, L(SmEu)-H(GdDy) has lower mechanical property parameters, meaning it also has the characteristic of being less prone to cracking.

[0092] The density test results show that the density of L(SmEu)-H(GdDy) is 6.341 g / cm³. 3 .

[0093] The results of the thermal diffusivity test are shown in Table 5 and Figure 4 As shown, the thermal diffusivity of L(SmEu)-H(GdDy) first decreases and then increases with increasing temperature, reaching 0.747 mm at 1200℃. 2 / s.

[0094] Table 5 Summary of Thermal Performance Parameters of L(SmEu)-H(GdDy)

[0095]

[0096] The specific heat capacity calculation results are shown in Table 5 and Figure 5 As shown, the specific heat capacity of L(SmEu)-H(GdDy) increases monotonically with increasing temperature, and the specific heat capacity is 0.527 J·g at 1200℃. -1 ·K -1 .

[0097] The thermal conductivity calculation results are shown in Table 5 and Figure 6 As shown, the thermal conductivity of L(SmEu)-H(GdDy) first decreases and then increases with increasing temperature, reaching a minimum value of 2.31 W·m at 800℃. -1 ·K -1 At a temperature of 1200℃, the thermal conductivity is 2.50 W·m. -1 ·K-1 Compared with L(Sm)-H(GdErYb) obtained in Example 1, it can be seen that, as with the conclusion of Comparative Example 1, the use of a C-(1:3) rare earth combination can significantly reduce thermal conductivity.

[0098] The calculated disorder of the A-site ion radius of L(SmEu)-H(GdDy) is 1.81%.

[0099] The results obtained from the calculation of thermal conductivity and A-site ion radius disorder are the same as those in Comparative Example 1.

[0100] As can be seen from Example 1 and Comparative Example 2, although the mechanical properties of the C-(2:2) rare earth combination are better than those of C-(1:3), the thermal properties of C-(2:2) do not meet the application requirements of thermal barrier coatings.

[0101] Comparative Example 3

[0102] A method for preparing C-(3:1) is described, with the steps not specifically described being the same as in Example 1, except that C-(1:3) is replaced with C-(3:1), that is, the rare earth combination consisting of one light rare earth element and three heavy rare earth elements is replaced with a rare earth combination consisting of three light rare earth elements and one heavy rare earth element. Specifically, the three light rare earth elements are Nd, Sm, and Eu, and the heavy rare earth element is Yb, resulting in a high-entropy rare earth aluminate (Nd) based on the light / heavy rare earth combination. 0.25 Sm 0.25 Eu 0.25 Yb 0.25 )4Al2O9, abbreviated as L(NdSmEu)-H(Yb).

[0103] XRD test results are as follows Figure 1 As shown, L(NdSmEu)-H(Yb) is a miscible structure.

[0104] As can be seen from Example 1 and Comparative Example 3, the rare earth combination using C-(3:1) exhibits phase separation, meaning it cannot form a single-phase structure.

[0105] Comparative Example 4

[0106] A method for preparing C-(4:0) is described, with the steps not specifically described being the same as in Example 1, except that C-(1:3) is replaced with C-(0:4), that is, the rare earth combination consisting of one light rare earth element and three heavy rare earth elements is replaced with a rare earth combination consisting of four light rare earth elements, specifically La, Nd, Sm, and Eu, to obtain a high-entropy rare earth aluminate (La) based on the light / heavy rare earth combination. 0.25 Nd 0.25 Sm 0.25 Eu 0.25)4Al2O9, abbreviated as L(LaNdSmEu).

[0107] XRD test results are as follows Figure 1 As shown, L(LaNdSmEu) is a miscible structure.

[0108] As can be seen from Example 1 and Comparative Example 4, the rare earth combination using C-(4:0) exhibits phase separation, meaning it cannot form a single-phase structure.

[0109] Example 2

[0110] A method for preparing high-entropy rare-earth aluminates based on a combination of light / heavy rare-earth elements is described. Unless otherwise specified, the steps are the same as in Example 1, except that the light rare-earth element is replaced by Nd instead of Sm, resulting in a high-entropy rare-earth aluminate based on a combination of light / heavy rare-earth elements (Nd). 0.25 Gd 0.25 Er 0.25 Yb 0.25 )4Al2O9, abbreviated as L(Nd)-H(GdErYb).

[0111] XRD test results are as follows Figure 1 As shown, L(Nd)-H(GdErYb) is a single-phase structure, with no phase transition and no impurity phase generated.

[0112] Microscopic morphology test results are as follows Figure 3 As shown, L(Nd)-H(GdErYb) contains Nd, Gd, Er, Yb, Al, and O elements, and each element exhibits a uniform and continuous distribution. The atomic contents of Nd, Gd, Er, and Yb are shown in Table 1, with the rare earth element atomic contents ranging from 8.93 to 9.75 at.%, consistent with stoichiometry. The test results indicate that L(Nd)-H(GdErYb) is a high-entropy ceramic.

[0113] The mechanical property test results are shown in Table 2. The Young's modulus of L(Nd)-H(GdErYb) is 218.4 GPa, the shear modulus is 86.6 GPa, the bulk modulus is 152.3 GPa, the Vickers hardness is 9.20 GPa, the flexural strength is 216.5 MPa, and the fracture toughness is 3.2 MPa·m. 1 / 2 .

[0114] The density test results show that the density of L(Nd)-H(GdErYb) is 7.204 g / cm³. 3 .

[0115] The results of the thermal diffusivity test are shown in Table 6 and Figure 4As shown, the thermal diffusivity of L(Nd)-H(GdErYb) first decreases and then increases with increasing temperature, reaching 0.557 mm at 1200℃. 2 / s.

[0116] Table 6 Summary of Thermal Performance Parameters of L(Nd)-H(GdErYb)

[0117]

[0118] The specific heat capacity calculation results are shown in Table 6 and Figure 5 As shown, the specific heat capacity of L(Nd)-H(GdErYb) increases monotonically with increasing temperature, and is 0.516 J·g at 1200℃. -1 ·K -1 .

[0119] The thermal conductivity calculation results are shown in Table 6 and Figure 6 As shown, the thermal conductivity of L(Nd)-H(GdErYb) first decreases and then increases with increasing temperature, reaching a minimum value of 1.94 W·m at 800℃. -1 ·K -1 At a temperature of 1200℃, the thermal conductivity is 2.07 W·m. -1 ·K -1 .

[0120] The calculated disorder of the A-site ion radius of L(Nd)-H(GdErYb) is 4.83%.

[0121] The conclusions drawn from the calculations of thermal conductivity and A-site ion radius disorder are the same as those in Example 1.

[0122] As can be seen from Examples 1 and 2, the mechanical and thermal properties of C-(1:3) meet the application requirements of thermal barrier coatings.

Claims

1. A high-entropy rare-earth aluminate based on light / heavy rare-earth combination, characterized in that: The chemical formula satisfies RE4Al2O9, wherein RE is a rare earth element combination, the rare earth element species is four, and the molar ratio is 1:1:1:1; The rare earth element combination is composed of one light rare earth element and three heavy rare earth elements, that is, a light / heavy rare earth combination.

2. The light / heavy rare earth combination high-entropy rare earth aluminates according to claim 1, characterized in that: The light rare earth element is one of La, Nd, Sm and Eu; and the heavy rare earth element is three of Gd, Dy, Ho, Er, Yb and Lu.

3. The light / heavy rare earth combination high-entropy rare earth aluminates of claim 1, wherein: The light / heavy rare earth combination based high-entropy rare earth aluminate has a single-phase structure and high-temperature stability in a temperature range of 20-1250℃.

4. A method for preparing a light / heavy rare earth combination high-entropy rare earth aluminates, characterized in that The method comprises the following steps: Light rare earth oxide, heavy rare earth oxide and Al2O3 are used as raw materials, the light rare earth oxide is first pre-sintered, then the light rare earth oxide, the heavy rare earth oxide and Al2O3 are first ball milled to obtain a first ball milling product, the first ball milling product is washed and dried, then the first ball milling product is first sintered to obtain a first sintering product, the ball milling is repeated under the same conditions after the first ball milling and the first sintering, that is, second ball milling is performed, and the second ball milling product is sieved with a mesh size of 200 mesh to obtain the light / heavy rare earth combination based high-entropy rare earth aluminate; The washing condition is that the washing solvent is anhydrous ethanol, and the washing is performed 5 times; and the drying condition is that the drying temperature is 80℃, and the drying time is 12 h.

5. The method of claim 4, wherein: The light rare earth oxide is Sm2O3 or Nd2O3, the heavy rare earth oxide is Gd2O3, Er2O3 and Yb2O3, and the chemical formula is RE4Al2O9, wherein RE is a rare earth element.

6. The method of claim 4, wherein: The pre-sintering condition is that the pre-sintering temperature is 1300℃, and the pre-sintering time is 1 h; The ball milling condition is that the ball milling rotation speed is 250 rpm, the ball milling medium is anhydrous ethanol, the material of the ball milling beads is zirconium oxide, the total ball milling time is 24 h, and the ball milling time is 6 h, and then the ball milling is paused for 30 min; The sintering condition is that the sintering temperature is 1600℃, and the sintering time is 4 h.

7. The light / heavy rare earth combination high-entropy rare earth aluminates of claim 1, wherein: As a thermal barrier coating material, the light / heavy rare earth combination based high-entropy rare earth aluminate is hot-pressed and sintered under argon gas and pressure conditions, that is, a heating process and a cooling process are performed to obtain a block-shaped light / heavy rare earth combination based high-entropy rare earth aluminate.

8. The light / heavy rare earth combination high-entropy rare earth aluminates according to claim 7, characterized in that: In the hot-pressing and sintering condition, The pressure condition is that the pressure temperature is 800℃, and the pressure is 30 MPa; The heating process is two-stage heating, the first-stage heating rate is 10℃ / min, the first-stage target temperature is 1000℃, the second-stage heating rate is 8℃ / min, the second-stage target temperature is 1750℃, and the second-stage holding time is 1 h; and the cooling process is two-stage cooling, the first-stage cooling rate is 10℃ / min, the first-stage target temperature is 1000℃, and the second-stage cooling is furnace cooling.

9. The light / heavy rare earth combination high-entropy rare earth aluminates of claim 8, wherein: The Young's modulus is 180-210 GPa, the shear modulus is 70-90 GPa, the bulk modulus is 130-150 GPa, the Vickers hardness is 9.1-9.2 GPa, the bending strength is 190-220 MPa, and the fracture toughness is 2.9-3.2 MPa·m 1 / 2 .

10. The light / heavy rare earth combination high-entropy rare earth aluminates of claim 8, wherein: The thermal conductivity is 1.61-1.87 W·m -1 ·K -1 In addition, at a high temperature of 1200℃, the thermal conductivity is 2.07-2.22 W·m -1 ·K -1 .

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