A high-entropy rare earth silicate ceramic coating material and preparation method thereof

Abstract

The present invention relates to a high entropy rare earth silicate ceramic coating material and a preparation method thereof, belonging to the technical field of high entropy ceramic materials. The phase composition of the coating material is A2Si2O7, A is Yb 0.1 Lu 0.1 Ho x Y 0.1 Sc 0.7‑x or Yb 0.2 Lu 0.2 Ho 0.2 Y 0.2 Sc 0.2 , x=0.1 or 0.6. The preparation method forms a slurry by wet ball milling the raw material powders and mixing them evenly; then drying, heating to 1400℃~1500℃ and calcining at a constant temperature for 6h~10h to obtain the coating material. The coating material can achieve the purpose of regulating the thermal expansion coefficient by controlling different values ​​of x. The five rare earth elements have equal molar ratios and are evenly distributed. The coating material has extremely low thermal conductivity and a thermal expansion coefficient that matches that of the silicon carbide substrate. It can achieve effective regulation of the thermal expansion coefficient, increase the service temperature of ultra-high temperature ceramics, and improve the service life of the coating.

Description

Technical Field

[0001] The invention relates to a high-entropy rare earth silicate ceramic coating material and a preparation method thereof, belonging to the technical field of high-entropy ceramic materials. Background Art

[0002] During their service, high-temperature components face a series of harsh conditions such as ultra-high temperatures, corrosion, and thermal shock. Therefore, a thermal protective coating needs to be applied to the surface to improve the service environment of high-temperature components and increase their service life. Thermal protective coating materials must have a low thermal conductivity to effectively hinder heat transfer and reduce the temperature of core components. In addition, the thermal expansion coefficient is one of the most important factors affecting the service life of the coating. Matching the thermal expansion coefficient with the substrate can effectively prevent the coating from cracking and failure. Therefore, it is of great significance to prepare a coating material with controllable thermal expansion coefficient and thermal conductivity.

[0003] Rare earth disilicates possess a thermal expansion coefficient matching that of silicon carbide (SiC), excellent high-temperature thermal stability, and oxidation resistance, making them promising thermal protection materials for ultra-high-temperature ceramic components. Rare earth disilicates have seven types of crystal structures, which can be determined by the ionic radius of the rare earth elements. Among them, β-RE2Si2O7 has a more stable structure and a lower thermal expansion coefficient. Density functional theory (DFT) studies of the atomic vibration modes of different crystal structures indicate that low-frequency phonons are contributed by the translation of the RE atoms in β-RE2Si2O7 combined with the intertetrahedral rotations of the SiO4 tetrahedrons. This suggests that the thermal properties of rare earth disilicates can be manipulated by varying the type of rare earth atoms. Therefore, exploring the correlation between the thermal properties of disilicates and the crystal structure differences caused by changes in the type and amount of ions provides a new approach to improving the thermal properties of disilicates.

[0004] High entropy rare earth silicates exhibit low thermal conductivity and have the potential to adjust the thermal expansion coefficient. The performance superposition and lattice distortion caused by atomic differences have attracted widespread attention. 0.2 Y 0.2 Lu 0.2 Sc 0.2 Gd 0.2 )2Si2O7、(Yb 0.2 Y 0.2 Lu 0.2 Ho 0.2 Er 0.2 )2Si2O7、(Lu 0.2 Yb 0.2 Er 0.2 Tm 0.2 Sc 0.2)2Si2O7 and other high-entropy rare earth silicates have shown that their lattice distortion will enhance the anharmonic vibration of the lattice, thereby reducing the thermal conductivity and changing the volume thermal expansion coefficient. However, the influence of its atomic species on the lattice thermal expansion coefficient and its enhancement mechanism are still unclear. Therefore, the prepared rare earth high-entropy silicates have a fixed thermal expansion coefficient and can only match a single matrix, which cannot effectively solve the fundamental problem of matching the thermal expansion coefficient with the matrix. Summary of the Invention

[0005] In order to overcome the problem that the thermal expansion coefficient is fixed and can only be matched with a single substrate, thereby limiting the application range of the coating, the purpose of the present invention is to provide a high-entropy rare earth silicate ceramic coating material and a preparation method thereof, wherein the coating material has extremely low thermal conductivity and a controllable thermal expansion coefficient.

[0006] To achieve the purpose of the present invention, the following technical solutions are provided.

[0007] A high entropy rare earth silicate ceramic coating material, the phase composition of the coating material is A2Si2O7, wherein A is Yb 0.1 Lu 0.1 Ho x Y 0.1 Sc 0.7-x or Yb 0.2 Lu 0.2 Ho 0.2 Y 0.2 Sc 0.2 , wherein x = 0.1 or 0.6; that is, the coating material is (Yb 0.1 Lu 0.1 Ho x Y 0.1 Sc 0.7-x )2Si2O7, wherein x=0.1 or 0.6; or the coating material is (Yb 0.2 Lu 0.2 Ho 0.2 Y 0.2 Sc 0.2 )2Si2O7.

[0008] A method for preparing the high entropy rare earth silicate ceramic coating material of the present invention comprises the following steps:

[0009] (1) According to the phase composition of the coating material, the raw material powders are weighed in a stoichiometric ratio and mixed uniformly by wet ball milling to form a slurry;

[0010] In step (1):

[0011] The raw material powders are powders of Yb2O3, Lu2O3, Ho2O3, Y2O3, Sc2O3 and SiO2.

[0012] Preferably, the particle size of the raw material powder is 1 μm to 5 μm, and the purity is ≥99.9%.

[0013] Preferably, the mass ratio of the ball mill to the raw material powder is 5:1.

[0014] Preferably, the ball milling medium is anhydrous ethanol.

[0015] Preferably, the ball milling speed is 250 r / min and the ball milling time is 6 h.

[0016] (2) Drying the slurry obtained in step (1) to obtain a powder, heating the powder to 1400° C. to 1500° C. and calcining the powder at a constant temperature for 6 h to 10 h to obtain a high entropy rare earth silicate ceramic coating material according to the present invention.

[0017] In step (2):

[0018] Preferably, drying is performed by rotary evaporation.

[0019] Preferably, the slurry is dried, ground, sieved, and the sieved powder is obtained, and then heated and calcined.

[0020] Preferably, the powder is heated to 1400°C to 1500°C at a rate of 5°C / min.

[0021] A high-entropy rare earth silicate ceramic coating is prepared on a SiC-based ultrahigh temperature ceramic substrate by using a high-entropy rare earth silicate ceramic coating material as described in the present invention.

[0022] Beneficial effects

[0023] (1) The present invention provides a high entropy rare earth silicate ceramic coating material, when the phase composition of the coating material is (Yb 0.1 Lu 0.1 Ho x Y 0.1 Sc 0.7-x )2Si2O7, where x = 0.1 or 0.6; by changing the value of x, different thermal expansion coefficients can be obtained. Therefore, the thermal expansion coefficient can be controlled by controlling the value of x.

[0024] The coating material achieves the purpose of reducing thermal conductivity and regulating thermal expansion coefficient by changing the ion doping ratio to control the ion radius difference of the system and utilizing the changes in microstructure and electronic structure brought about by the ion radius difference. By controlling the microstructure and electronic structure, the thermal expansion coefficient of the double silicate is achieved within 4.57×10 -6 K -1 ~5.04×10 -6 K -1The effective regulation of the time interval improves the reliability of double silicate as a SiC-based coating; the five rare earth elements are evenly distributed, and the thermal conductivity is only 1.13W / m·K.

[0025] (2) The present invention provides a high entropy rare earth silicate ceramic coating material, when the phase composition of the coating material is (Yb 0.2 Lu 0.2 Ho 0.2 Y 0.2 Sc 0.2 )2Si2O7, the five rare earth elements have equal molar ratios and are evenly distributed. The coating material has extremely low thermal conductivity. The thermal conductivity of the sample measured by a laser thermal conductivity meter between room temperature and 1200°C is 1.14W / m·K; the thermal expansion coefficient is 4.84×10 -6 K -1 , has a thermal expansion coefficient that matches that of silicon carbide (SiC), providing more possibilities for double silicates as silicon carbide-based coating materials.

[0026] (3) The present invention provides a method for preparing a high-entropy rare earth silicate ceramic coating material. The method not only provides a new thermal protection coating material for a silicon carbide-based ultra-high temperature ceramic substrate, but also provides a new technical idea for regulating the thermal expansion coefficient to match different substrates. By exploring the mechanism of the influence of element doping on thermal performance at the electronic scale, the thermal expansion coefficient can be effectively regulated, and ultimately the service temperature of ultra-high temperature ceramics and the service life of the coating are increased. This method is of great significance to the selection of ultra-high temperature silicon carbide-based thermal protection coating materials.

[0027] (4) The present invention provides a method for preparing a high-entropy rare earth silicate ceramic coating material. In the preparation method, in step (1), the raw material powder is fully and evenly mixed by wet ball milling, so that the high-entropy rare earth silicate ceramic elements synthesized at high temperature are evenly distributed, and there will be no agglomeration and enrichment of a certain rare earth element;

[0028] The raw material powders preferably have a particle size of 1 μm to 5 μm and a purity of ≥99.9%. Uniform raw material powder particle size effectively improves the uniformity of the phase composition of the synthesized product. High purity ensures the synthesis effect while preventing the introduction of impurities, ensuring the uniformity of the phase composition of the product.

[0029] (5) The present invention provides a method for preparing a high-entropy rare earth silicate ceramic coating material. In the preparation method, in step (2), the material is calcined at a constant temperature of 1400°C to 1500°C for 6h to 10h. If the calcination is not satisfied, the final product prepared will contain a second phase such as SiO2 in addition to the coating material of the present invention, which will affect the purity of the material and thus affect the thermophysical properties of the material.

[0030] Preferably, the slurry is dried and then ground and sieved to obtain a sieved powder, so that the calcined powder particles are uniform, and the high entropy rare earth silicate ceramic coating material prepared by the present invention has a uniform particle size distribution and good particle morphology.

[0031] (6) The present invention provides a high-entropy rare earth silicate ceramic coating, which adopts a high-entropy rare earth silicate ceramic coating material described in the present invention; it is suitable for use with a SiC-based ultra-high temperature ceramic substrate; it successfully achieves the purpose of increasing the service temperature of ultra-high temperature ceramics and improving the service life of the coating; and it has a wide range of application scenarios in the field of thermal protection coatings for key high-end equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The X-ray diffraction (XRD) patterns of the powder samples prepared in Examples 1 and 2 are shown.

[0033] Figure 2 Thermal conductivity diagram of the bulk samples prepared in Examples 1 and 2.

[0034] Figure 3 Graphs of thermal expansion coefficients of bulk samples prepared in Examples 1 and 2.

[0035] Figure 4 This is the XRD pattern of the powder sample prepared in Example 3.

[0036] Figure 5 This is the SEM-EDS image of the powder sample prepared in Example 3.

[0037] Figure 6 This is the thermal conductivity diagram of the bulk sample prepared in Example 3.

[0038] Figure 7 This is the thermal expansion rate diagram of the bulk sample prepared in Example 3.

[0039] Figure 8 This is the thermal expansion coefficient diagram of the bulk sample prepared in Example 3. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but this does not limit the present invention.

[0041] In the following embodiments:

[0042] The particle sizes of the raw material powders Yb2O3, Lu2O3, Ho2O3, Y2O3, Sc2O3 and SiO2 are all 1μm to 5μm, and the purity is ≥99.9%.

[0043] The prepared powder samples and block samples were tested as follows:

[0044] (1) X-ray diffraction (XRD)

[0045] Manufacturer: PANalytical, Netherlands, Instrument Model: Empyrean. Tests were conducted using a Cu target, operating voltage 45 kV, current 40 mA, scan speed 10.2 s per step, and step size 0.013.

[0046] (2) Field emission scanning electron microscopy

[0047] Manufacturer: Carl Zeiss, Instrument Model: PANalytical EmpyreanZeiss / Auriga. The sample to be tested was ground and polished to a thickness of less than 0.5 mm, and the surface polished to a mirror finish with no noticeable stains. The surface was then gold-sprayed and tested for surface morphology. Composition analysis of the sample was performed using an energy dispersive spectrometer equipped with a scanning electron microscope.

[0048] (3) Thermal conductivity

[0049] Manufacturer: NETZSCH Instruments, Germany, Instrument Model: LFA-457. A laser thermal conductivity meter was used to test the thermal conductivity of the prepared high-entropy rare earth silicate ceramic blocks between room temperature and 1200°C. The samples were cut into 12.7mm diameter discs, which were then polished to a thickness of less than 3mm and a bright finish.

[0050] (4) Thermal expansion rate and coefficient

[0051] The thermal expansion rate of the sample was measured using a high-temperature thermal expansion instrument, and the thermal expansion coefficient of the sample at different temperatures was obtained using conventional calculation methods.

[0052] Manufacturer: NETZSCH Instruments GmbH, Germany, Instrument Model: DIL402PC. Cut the block to be tested into 3mm × 3mm × 30mm blocks, polish until both ends are parallel, and place it in the instrument for testing.

[0053] Unless otherwise specified, the experimental materials described in the present invention can be obtained from commercial channels, and the experimental methods described are conventional methods unless otherwise specified.

[0054] Example 1

[0055] (1) According to the phase composition of the coating material (Yb 0.1 Lu 0.1 Ho 0.1 Y 0.1 Sc 0.6 )2Si2O7, weigh each raw material powder using the stoichiometric ratio:

[0056] Weigh Yb2O3, Lu2O3, Ho2O3, Y2O3, Sc2O3 and SiO2 in a molar ratio of 1:1:1:1:6:20;

[0057] The weighed raw material powder and zirconia grinding balls are placed in a ball mill at a mass ratio of 1:5. Anhydrous ethanol is added to cover the grinding balls and raw material powder as the ball milling medium for wet grinding and mixing. The mixture is ball milled on a planetary ball mill at a speed of 250 r / min for 6 hours to form a slurry.

[0058] (2) The slurry obtained in step (1) was dried at 55°C using a rotary evaporator, and the dried powder was ground using an agate mortar and passed through 100-mesh and 300-mesh sieves respectively to obtain a sieved powder; the sieved powder was placed in an alumina crucible, placed in a pressureless box sintering furnace, heated to 1400°C at a rate of 5°C / min, and calcined at a constant temperature for 10 hours to prepare a final product powder; then the temperature was cooled to room temperature with the furnace, and the powder was taken out and ground using a mortar until no obvious particles were found, as a powder sample for testing.

[0059] In order to perform scanning electron microscope observation, thermal conductivity and thermal expansion coefficient testing, the powder sieved in step (2) of this embodiment needs to be made into a bulk sample for testing. The specific method is as follows:

[0060] The sieved powder was initially compressed using a manual tablet press, using a 20 mm diameter circular mold and a 5 mm × 5 mm × 50 mm bar mold, at a pressure of 8 MPa and a holding time of 1 min. A secondary compression was then performed using cold isostatic pressing at a pressure of 250 MPa and a holding time of 5 min to obtain a green body.

[0061] The green body was placed in an alumina crucible, placed in a pressureless box sintering furnace, heated to 1400°C at a rate of 5°C / min and calcined at a constant temperature for 10 hours to prepare a block sample for testing; and cooled to room temperature along with the furnace.

[0062] The powder samples and block samples prepared in this example were tested as follows:

[0063] (1) X-ray diffraction (XRD)

[0064] The test results are as follows Figure 1 As shown, it can be seen that the powder sample has a typical double silicate structure without impurity peaks, proving that the final product is a single-phase high-entropy double silicate.

[0065] (2) Scanning electron microscopy-energy dispersive spectrometry (SEM-EDS)

[0066] The microstructure and element distribution of the powder sample were observed using SEM-EDS. The results showed that all elements were evenly distributed without obvious segregation.

[0067] In summary, it can be seen that the final product prepared in this embodiment is a high entropy rare earth silicate ceramic coating material (Yb 0.1 Lu 0.1 Ho 0.1 Y 0.1 Sc 0.6 )2Si2O7.

[0068] (3) Thermal conductivity

[0069] The thermal conductivity test results of the cooled bulk sample are as follows: Figure 2 As shown, the thermal conductivity is as low as 1.13 W / m·K, which indicates good thermal insulation performance.

[0070] (4) Thermal expansion coefficient

[0071] The thermal expansion coefficient test results of the cooled block sample are as follows: Figure 3 As shown, the thermal expansion coefficient is 5.04×10 -6 K -1 .

[0072] Example 2

[0073] (1) According to the phase composition of the coating material (Yb 0.1 Lu 0.1 Ho 0.6 Y 0.1 Sc 0.1 )2Si2O7, weigh each raw material powder using the stoichiometric ratio:

[0074] Weigh Yb2O3, Lu2O3, Ho2O3, Y2O3, Sc2O3 and SiO2 in a molar ratio of 1:1:6:1:1:20;

[0075] The weighed raw material powder and zirconia grinding balls are placed in a ball mill at a mass ratio of 1:5. Anhydrous ethanol is added to cover the grinding balls and raw material powder as the ball milling medium for wet grinding and mixing. The mixture is ball milled on a planetary ball mill at a speed of 250 r / min for 6 hours to form a slurry.

[0076] (2) The temperature was raised to 1500° C. and calcined at a constant temperature for 6 h. The rest was the same as step (2) of Example 1.

[0077] In order to perform scanning electron microscope observation, thermal conductivity and thermal expansion coefficient testing, the powder sieved in step (2) of this embodiment needs to be made into a bulk sample for testing. The specific method is as follows:

[0078] The sieved powder was initially compressed using a manual tablet press, using a 20 mm diameter circular mold and a 5 mm × 5 mm × 50 mm bar mold, at a pressure of 8 MPa and a holding time of 1 min. A secondary compression was then performed using cold isostatic pressing at a pressure of 250 MPa and a holding time of 5 min to obtain a green body.

[0079] The green body was placed in an alumina crucible, placed in a pressureless box sintering furnace, heated to 1500°C at a rate of 5°C / min and calcined at a constant temperature for 6 hours to prepare a block sample for testing; and cooled to room temperature along with the furnace.

[0080] The powder samples and block samples prepared in this example were tested as follows:

[0081] (1) X-ray diffraction (XRD)

[0082] The test results are as follows Figure 1 As shown, it can be seen that the powder sample has a typical double silicate structure without impurity peaks, proving that the final product is a single-phase high-entropy double silicate.

[0083] (2) Scanning electron microscopy-energy dispersive spectrometry (SEM-EDS)

[0084] The microstructure and element distribution of the powder sample were observed using SEM-EDS. The results showed that all elements were evenly distributed without obvious segregation.

[0085] In summary, it can be seen that the final product prepared in this embodiment is a high entropy rare earth silicate ceramic coating material (Yb 0.1 Lu 0.1 Ho 0.6 Y 0.1 Sc 0.1 )2Si2O7.

[0086] (3) Thermal conductivity

[0087] The thermal conductivity test results of the cooled bulk sample are as follows: Figure 2 As shown, the thermal conductivity is as low as 1.59 W / m·K, which indicates good thermal insulation performance.

[0088] (4) Thermal expansion coefficient

[0089] The thermal expansion coefficient test results of the cooled block sample are as follows: Figure 3 As shown, the thermal expansion coefficient is 4.08×10 -6 K -1 .

[0090] The thermal expansion coefficient test results of Examples 1 and 2 show that the thermal expansion coefficient of the high entropy rare earth silicate ceramic coating material of the present invention can be effectively achieved in the range of 4.08×10 -6 K -1 ~5.04×10 -6 K -1 Regulation between.

[0091] Example 3

[0092] (1) According to the phase composition of the coating material (Yb 0.2 Lu 0.2 Ho 0.2 Y 0.2 Sc 0.2 )2Si2O7, weigh each raw material powder using the stoichiometric ratio:

[0093] Weigh Yb2O3, Lu2O3, Ho2O3, Y2O3, Sc2O3 and SiO2 in a molar ratio of 1:1:1:1:1:10;

[0094] The weighed raw material powder and zirconia grinding balls are placed in a ball mill at a mass ratio of 1:5. Anhydrous ethanol is added to cover the grinding balls and raw material powder as the ball milling medium for wet grinding and mixing. The mixture is ball milled on a planetary ball mill at a speed of 250 r / min for 6 hours to form a slurry.

[0095] (2) The slurry obtained in step (1) was dried at 65°C using a rotary evaporator, and the dried powder was ground using an agate mortar and passed through 100-mesh and 300-mesh sieves respectively to obtain a sieved powder; the sieved powder was placed in an alumina crucible, placed in a pressureless box sintering furnace, and heated to 1450°C at a rate of 5°C / min and calcined at a constant temperature for 8h to prepare a final product powder; then the temperature was cooled to room temperature with the furnace, and the powder was taken out and ground using a mortar until no obvious particles were present, as a powder sample for testing.

[0096] In order to perform scanning electron microscope observation, thermal conductivity and thermal expansion coefficient testing, the powder sieved in step (2) of this embodiment needs to be made into a bulk sample for testing. The specific method is as follows:

[0097] The sieved powder was initially compressed using a manual tablet press, using a 20 mm diameter circular mold and a 5 mm × 5 mm × 50 mm bar mold, at a pressure of 8 MPa and a holding time of 1 min. A secondary compression was then performed using cold isostatic pressing at a pressure of 250 MPa and a holding time of 5 min to obtain a green body.

[0098] The green body was placed in an alumina crucible, placed in a pressureless box sintering furnace, heated to 1450°C at a rate of 5°C / min, and calcined at a constant temperature for 8 hours to prepare a bulk sample for testing; and then cooled to room temperature along with the furnace.

[0099] The powder samples and block samples prepared in this example were tested as follows:

[0100] (1) X-ray diffraction (XRD)

[0101] The test results are as follows Figure 4 As shown, it can be seen that the powder sample has a typical double silicate structure without impurity peaks, proving that the final product is a single-phase high-entropy double silicate.

[0102] (2) Scanning electron microscopy-energy dispersive spectrometry (SEM-EDS)

[0103] The powder sample was observed using SEM-EDS to observe its microstructure and element distribution. The results are as follows: Figure 5 As shown, all elements are evenly distributed without obvious segregation.

[0104] In summary, it can be seen that the final product prepared in this embodiment is a high entropy rare earth silicate ceramic coating material (Yb 0.2 Lu 0.2 Ho 0.2 Y 0.2 Sc 0.2 )2Si2O7.

[0105] (3) Thermal conductivity

[0106] The thermal conductivity test results of the cooled bulk sample are as follows: Figure 6 As shown, it can be seen that the coating material has an extremely low thermal conductivity of only 1.14 W / m·K.

[0107] (4) Thermal expansion rate and coefficient

[0108] The thermal expansion rate of the cooled bulk sample is as follows: Figure 7 As shown, it shows typical linear thermal expansion, indicating that the coating material has good thermal stability.

[0109] The thermal expansion coefficient of the cooled bulk sample is as follows: Figure 8 As shown, the thermal expansion coefficient of the coating material is 4.84×10 -6 K -1 , close to silicon carbide.

Claims

1. A high-entropy rare earth silicate ceramic coating material, characterized by: The phase composition of the coating material is A2Si2O7, wherein A is Yb 0.1 Lu 0.1 Ho x Y 0.1 Sc 0.7-x , x=0.1 or 0.

6.

2. A method for preparing the high-entropy rare earth silicate ceramic coating material according to claim 1, characterized in that: The method steps are as follows: (1) According to the phase composition of the coating material, the raw material powders are weighed in a stoichiometric ratio and mixed uniformly by wet ball milling to form a slurry; The raw material powder is powder of Yb2O3, Lu2O3, Ho2O3, Y2O3, Sc2O3 and SiO2; (2) The slurry is dried to obtain a powder, and the powder is heated to 1400°C to 1500°C and calcined at a constant temperature for 6h to 10h to prepare a high entropy rare earth silicate ceramic coating material.

3. The method for preparing a high entropy rare earth silicate ceramic coating material according to claim 2, characterized in that: In step (1), the particle size of the raw material powder is 1 μm to 5 μm, and the purity is ≥99.9%.

4. The method for preparing a high-entropy rare earth silicate ceramic coating material according to claim 2 or 3, characterized in that: In step (1), the mass ratio of the grinding balls to the raw material powder is 5:1; the ball milling medium is anhydrous ethanol; the ball milling speed is 250 r / min, and the ball milling time is 6 h.

5. The method for preparing a high entropy rare earth silicate ceramic coating material according to claim 2, characterized in that: In step (2), rotary evaporation is used for drying.

6. The method for preparing a high entropy rare earth silicate ceramic coating material according to claim 2, characterized in that: In step (2), the slurry is dried and then ground and sieved to obtain the sieved powder, which is then heated and calcined.

7. The method for preparing a high entropy rare earth silicate ceramic coating material according to claim 2, characterized in that: In step (2), the powder is heated at a rate of 5°C / min.

8. The method for preparing a high entropy rare earth silicate ceramic coating material according to claim 2, characterized in that: In step (2), rotary evaporation is used for drying; after the slurry is dried, it is ground and sieved to obtain a sieved powder, which is then heated and calcined; the powder is heated at a rate of 5°C / min.

9. The method for preparing a high-entropy rare earth silicate ceramic coating material according to claim 2, wherein: In step (1), the particle size of the raw material powder is 1 μm to 5 μm, and the purity is ≥99.9%; the mass ratio of the grinding balls to the raw material powder is 5:1; the ball milling medium is anhydrous ethanol; the ball milling speed is 250 r / min, and the ball milling time is 6 h; In step (2), rotary evaporation is used for drying; after the slurry is dried, it is ground and sieved to obtain a sieved powder, which is then heated and calcined; the powder is heated at a rate of 5°C / min.

10. A high-entropy rare earth silicate ceramic coating, characterized in that: The coating is prepared on a SiC-based ultrahigh temperature ceramic substrate using a high entropy rare earth silicate ceramic coating material as described in claim 1.

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