High-entropy rare-earth silicate ceramic nanopowder, method of making and applications thereof

Abstract

This invention discloses high-entropy rare-earth silicate ceramic nanopowders, their preparation methods, and applications. The preparation method of the high-entropy rare-earth silicate ceramic nanopowders of this invention includes the following steps: 1) dissolving rare-earth oxide powder in an acid solution to prepare a rare-earth salt solution, then adding urea and silica powder and performing a gelation reaction to obtain a gel; 2) igniting the gel for combustion synthesis, grinding, and obtaining a precursor powder; 3) calcining the precursor powder to obtain the high-entropy rare-earth silicate ceramic nanopowders. The high-entropy rare-earth silicate ceramic nanopowders of this invention possess excellent characteristics such as fine particle size, uniform elemental distribution, large component space, and absence of impurities. Furthermore, its preparation method has advantages such as fast synthesis speed, simple equipment, simple and controllable process, and low industrialization cost, making it suitable for application in hot-end components of aerospace engines and possessing very broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of high-entropy ceramics technology, specifically to high-entropy rare-earth silicate ceramic nanopowders, their preparation methods, and applications. Background Technology

[0002] High-entropy rare-earth silicates (belonging to the high-entropy oxide system) have excellent properties such as good high-temperature phase stability, excellent corrosion resistance, and excellent physicochemical compatibility with silicon-based ceramic matrices. They are considered to be the best candidate materials for the next generation of environmental barrier coatings and have a very broad application prospect in the hot-end components of aerospace engines.

[0003] Currently, the main methods for preparing high-entropy rare-earth silicate ceramic powders include solid-state reaction and sol-gel methods. Solid-state reaction methods have advantages such as low cost, high yield, and simple preparation processes, making them the most commonly used method for synthesizing high-entropy rare-earth silicate ceramic powders (e.g., Equiatomic quaternary (Y) 1 / 4 Ho 1 / 4 Er 1 / 4 Yb 1 / 4 (2SiO5 silicate: Aperspective multifunctional thermal and environmental barrier coating material, Xiaomin Ren, Zhilin Tian, ​​Jie Zhang, Jingyang Wang. Scripta Materialia, 2019, 168: 47-50). However, this method has problems such as high synthesis temperature (≥1550℃), large powder particle size (30μm~40μm), uneven element distribution, impurity phase, and small component space, which seriously limit the development and application of high-performance high-entropy rare earth silicate ceramics. The sol-gel method (e.g., High-entropy environmental barrier coating for the ceramic matrix composites, Yu Dong, Ke Ren, Yonghong Lu, Qiankun Wang, Jia Liu, Yiguang Wang. Journal of the European Ceramic Society, 2019, 39: 2574-2579) has problems such as complex preparation process, high environmental pollution, and many influencing factors that are difficult to control. In addition, the prepared powder particles have a large size (5μm to 30μm). Furthermore, the sol-gel method cannot prepare high-entropy rare earth monosilicate powders (the preparation is difficult), which greatly limits its application.

[0004] Therefore, it is of great significance to develop a method for preparing high-entropy rare earth silicate ceramic powder that is simple to use, has a simple and controllable process, low industrialization cost, and is convenient and fast, and to prepare high-entropy rare earth silicate ceramic nanopowder with fine particle size, uniform element distribution, high purity, and large component space. Summary of the Invention

[0005] The purpose of this invention is to provide high-entropy rare-earth silicate ceramic nanopowders, their preparation methods, and applications.

[0006] The technical solution adopted in this invention is:

[0007] A method for preparing high-entropy rare-earth silicate ceramic nanopowder includes the following steps:

[0008] 1) A rare earth oxide powder is dissolved in an acid solution to prepare a rare earth salt solution. The rare earth oxide powder is composed of at least four of the following: Sc2O3 powder, Y2O3 powder, Sm2O3 powder, Eu2O3 powder, Gd2O3 powder, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder, and Lu2O3 powder. Urea and silica powder are then added, and a gelation reaction is carried out to obtain a gel.

[0009] 2) The gel is ignited for combustion synthesis, then ground to obtain precursor powder;

[0010] 3) The precursor powder is calcined to obtain high-entropy rare earth silicate ceramic nanopowder.

[0011] Preferably, the rare earth oxide powder in step 1) is composed of at least four of the following powders in equimolar ratio: Sc2O3 powder, Y2O3 powder, Sm2O3 powder, Eu2O3 powder, Gd2O3 powder, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder, and Lu2O3 powder.

[0012] Preferably, the rare earth oxide powder in step 1) has a particle size of 1μm to 3μm and a purity of ≥99.9%.

[0013] Preferably, the acid solution in step 1) is at least one of nitric acid solution and hydrochloric acid solution.

[0014] Preferably, the urea (CO(NH2)2) in step 1) is of analytical grade.

[0015] Preferably, the silica powder in step 1) has a particle size of 40 nm to 60 nm and a purity of ≥99.9%.

[0016] Preferably, the ratio of the total molar amount of rare earth oxide powder to the molar amount of urea in step 1) is 1:2.50 to 2.75.

[0017] Preferably, the ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of silicon atoms in the silica powder in step 1) is 1:0.4 to 0.5 (for synthesizing high-entropy rare earth monosilicate powder), or the ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of silicon atoms in the silica powder in step 1) is 1:1.05 to 1.15 (for synthesizing high-entropy rare earth disilicate powder).

[0018] Preferably, the gelation reaction in step 1) is carried out at a temperature of 80℃ to 120℃ for a reaction time of 3h to 5h.

[0019] Preferably, the gelation reaction in step 1) is carried out under stirring.

[0020] Preferably, the ignition temperature for combustion synthesis in step 2) is 400℃~600℃, and the synthesis time is 3min~10min.

[0021] Preferably, the grinding time in step 2) is 20 min to 30 min.

[0022] Preferably, the specific operation of calcination in step 3) is as follows: first, control the heating rate to 6℃ / min~8℃ / min to raise the temperature from room temperature to 1250℃~1350℃, then keep it at that temperature for 0.5h~3h, and then cool it down to room temperature with the furnace.

[0023] A high-entropy rare-earth silicate ceramic nanopowder is prepared by the above-described method.

[0024] Preferably, the average particle size of the high-entropy rare-earth silicate ceramic nanopowder is 60 nm to 80 nm.

[0025] Preferably, the high-entropy rare-earth silicate ceramic nanopowder has a uniform distribution of elements and is free of impurity phases.

[0026] An environmental barrier coating comprising the aforementioned high-entropy rare-earth silicate ceramic nanoparticles.

[0027] An aerospace engine in which the surface of a hot-end component is covered with the aforementioned environmental barrier coating.

[0028] The beneficial effects of this invention are: the high-entropy rare earth silicate ceramic nanopowder of this invention has excellent characteristics such as small particle size, uniform element distribution, large component space, and no impurities. Moreover, its preparation method has the advantages of fast synthesis speed, simple equipment, simple and controllable process, and low industrialization cost. It is suitable for application in hot-end components of aerospace engines and has a very broad application prospect.

[0029] Specifically:

[0030] 1) The method for preparing high-entropy rare-earth silicate ceramic nanopowder of the present invention has the advantages of simple equipment, simple and controllable process, low industrialization cost, and convenience and speed.

[0031] 2) The high-entropy rare earth silicate ceramic powder preparation method of the present invention can prepare high-entropy rare earth monosilicate nanopowders (X2-RE2SiO5 structure) and high-entropy rare earth disilicate nanopowders (β-RE2Si2O7 structure) with huge component space, and can easily synthesize high-entropy rare earth monosilicate nanopowders that are more difficult to prepare.

[0032] 3) The high-entropy rare earth silicate ceramic nanopowder of the present invention has excellent characteristics such as small particle size (60nm~80nm), uniform element distribution, large component space, and no impurity phase. Moreover, the morphology of the powder is easy to control, which is beneficial to subsequent sintering and is suitable for application in hot end components of aerospace engines. Attached Figure Description

[0033] Figure 1 The images show the XRD patterns of the high-entropy rare-earth silicate ceramic nanopowders from Examples 1-3.

[0034] Figure 2 The images shown are SEM, SEM-EDS, TEM, SAED, HRTEM, and STEM-EDS images of the high-entropy rare-earth silicate ceramic nanopowder from Example 1.

[0035] Figure 3 The images show the XRD patterns of the high-entropy rare-earth silicate ceramic nanopowders from Examples 4-6.

[0036] Figure 4 The images show the XRD patterns of high-entropy rare-earth silicate ceramic powders from Comparative Examples 1 and 2. Detailed Implementation

[0037] The present invention will be further explained and described below with reference to specific embodiments.

[0038] The particle sizes of Sc2O3 powder, Y2O3 powder, Sm2O3 powder, Eu2O3 powder, Gd2O3 powder, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder, and Lu2O3 powder in Examples 1-6 and Comparative Examples 1-2 were all 1μm to 3μm, and their purity was ≥99.9%. The particle size of silica powder was 40nm to 60nm, and its purity was ≥99.9%. The purity of urea was analytical grade.

[0039] The silica powder in Comparative Example 3 has a particle size of 1 μm to 3 μm and a purity of ≥99.9%.

[0040] Example 1:

[0041] A high-entropy rare-earth silicate ceramic nanopowder is prepared by the following method:

[0042] 1) Dissolve 0.9563g of Er2O3 powder, 0.9646g of Tm2O3 powder, 0.9852g of Yb2O3 powder and 0.9948g of Lu2O3 powder in 40mL of boiling dilute nitric acid solution (mass fraction of 32%) to prepare a rare earth salt solution. Then add 1.5734g of urea and 0.5708g of silica powder, and stir at 80℃ (3h~5h) until a homogeneous and viscous gel is formed.

[0043] 2) After loading the gel into a crucible, place it in a muffle furnace and ignite it at 400°C for 5 minutes to obtain a loosely structured foam-like precursor. Grind it for 20 minutes to obtain the precursor powder.

[0044] 3) Place the precursor powder in a muffle furnace, first control the heating rate to rise from room temperature to 1250℃ at 8℃ / min, then hold at that temperature for 0.5h, and then cool with the furnace to room temperature to obtain high-entropy rare earth silicate ceramic nanopowder (quaternary high-entropy rare earth monosilicate (Er)). 1 / 4 Tm 1 / 4 Yb 1 / 4 Lu 1 / 4 )2SiO5, denoted as 4-HEREM).

[0045] Performance testing:

[0046] The X-ray diffraction (XRD) pattern of the high-entropy rare-earth silicate ceramic nanopowder (4-HEREM) in this embodiment is shown below. Figure 1 As shown, the scanning electron microscope (SEM) image, the corresponding energy dispersive spectroscopy (SEM-EDS) image, the transmission electron microscope (TEM) image, the selected area electron diffraction (SAED) image, the high-resolution transmission electron microscope (HRTEM) image, and the corresponding energy dispersive spectroscopy (STEM-EDS) image are as follows: Figure 2 (a is a SEM image, b is a SEM-EDS image, c is a TEM image, d is a SAED image, and e is an HRTEM image and a STEM-EDS image.)

[0047] Depend on Figure 1 It can be seen that the high-entropy rare earth silicate ceramic nanopowder in this embodiment has a single X2-RE2SiO5 structure and no other impurity phases were found.

[0048] Depend on Figure 2It can be seen that the morphology of the high-entropy rare earth silicate ceramic nanopowder in this embodiment is mainly spherical particles, with some particles connected to each other and necking, and an average particle size of about 60 nm. The rare earth elements are evenly distributed and there is no obvious segregation.

[0049] Example 2:

[0050] A high-entropy rare-earth silicate ceramic nanopowder is prepared by the following method:

[0051] 1) Dissolve 0.2298g of Sc2O3 powder, 0.5812g of Sm2O3 powder, 0.5865g of Eu2O3 powder, 0.6298g of Ho2O3 powder, 0.6375g of Er2O3 powder and 0.6632g of Lu2O3 powder in 50mL of boiling dilute nitric acid solution (mass fraction of 32%) to prepare a rare earth salt solution. Then add 1.6339g of urea and 0.5528g of silica powder, and stir at 90℃ (3h~5h) until a homogeneous viscous gel is formed.

[0052] 2) After loading the gel into a crucible, place it in a muffle furnace and ignite it at 500°C for 8 minutes to obtain a loosely structured foam-like precursor. Grind it for 25 minutes to obtain the precursor powder.

[0053] 3) Place the precursor powder in a muffle furnace, first control the heating rate to rise from room temperature to 1300℃ at 7℃ / min, then hold at that temperature for 1 hour, and then cool with the furnace to room temperature to obtain high-entropy rare earth silicate ceramic nanopowder (hexa-membered high-entropy rare earth monosilicate (Sc)). 1 / 6 Sm 1 / 6 Eu 1 / 6 Ho 1 / 6 Er 1 / 6 Lu 1 / 6 )2SiO5, denoted as 6-HEREM).

[0054] Performance testing:

[0055] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (6-HEREM) in this embodiment is shown below. Figure 1 As shown.

[0056] Depend on Figure 1 It can be seen that the high-entropy rare earth silicate ceramic nanopowder in this embodiment has a single X2-RE2SiO5 structure and no other impurity phases were found.

[0057] Furthermore, SEM and STEM-EDS energy dispersive spectroscopy elemental distribution tests revealed that the high-entropy rare-earth silicate ceramic nanopowder in this embodiment has an irregular particle morphology with an average particle size of approximately 60 nm. The distribution of each metal element is uniform, with no obvious segregation.

[0058] Example 3:

[0059] A high-entropy rare-earth silicate ceramic nanopowder is prepared by the following method:

[0060] 1) Dissolve 0.1724g of Sm2O3 powder, 0.4531g of Gd2O3 powder, 0.4662g of Dy2O3 powder, 0.4723g of Ho2O3 powder, 0.4781g of Er2O3 powder, 0.4823g of Tm2O3 powder, 0.4926g of Yb2O3 powder and 0.4974g of Lu2O3 powder in 60mL of boiled dilute hydrochloric acid solution (mass fraction of 20%) to prepare a rare earth salt solution. Then add 1.6642g of urea and 0.5407g of silica powder, and stir at 100℃ (3h~5h) until a homogeneous and viscous gel is formed.

[0061] 2) After loading the gel into a crucible, place it in a muffle furnace and ignite it at 600℃ for 10 min to obtain a loosely structured foam-like precursor. Grind it for 30 min to obtain the precursor powder.

[0062] 3) Place the precursor powder in a muffle furnace, first control the heating rate to rise from room temperature to 1350℃ at 6℃ / min, then hold at that temperature for 1 hour, and then cool with the furnace to room temperature to obtain high-entropy rare earth silicate ceramic nanopowder (octagonal high-entropy rare earth monosilicate (Sm)). 1 / 8 Gd 1 / 8 Dy 1 / 8 Ho 1 / 8 Er 1 / 8 Tm 1 / 8 Yb 1 / 8 Lu 1 / 8 )2SiO5, denoted as 8-HEREM).

[0063] Performance testing:

[0064] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (8-HEREM) in this embodiment is shown below. Figure 1 As shown.

[0065] Depend on Figure 1 It can be seen that the high-entropy rare earth silicate ceramic nanopowder in this embodiment has a single X2-RE2SiO5 structure and no other impurity phases were found.

[0066] Furthermore, SEM and STEM-EDS elemental distribution tests revealed that the high-entropy rare-earth silicate ceramic nanopowder in this embodiment has an irregular particle morphology with an average particle size of approximately 80 nm. The distribution of each metal element is uniform, with no obvious segregation.

[0067] Example 4:

[0068] A high-entropy rare-earth silicate ceramic nanopowder is prepared by the following method:

[0069] 1) Dissolve 0.5645g of Y2O3 powder, 0.9325g of Dy2O3 powder, 0.9852g of Yb2O3 powder and 0.9948g of Lu2O3 powder in 60mL of boiling dilute hydrochloric acid solution (mass fraction of 20%) to prepare a rare earth salt solution. Then add 1.5734g of urea and 1.2617g of silica powder, and stir at 80℃ (3h~5h) until a homogeneous and viscous gel is formed.

[0070] 2) After loading the gel into a crucible, place it in a muffle furnace and ignite it at 400°C for 3 minutes to obtain a loosely structured foam-like precursor. Grind it for 20 minutes to obtain the precursor powder.

[0071] 3) Place the precursor powder in a muffle furnace, first control the heating rate to rise from room temperature to 1250℃ at 8℃ / min, then hold for 2 hours, and then cool with the furnace to room temperature to obtain high-entropy rare earth silicate ceramic nanopowder (quaternary high-entropy rare earth bissilicate (Y)). 1 / 4 Dy 1 / 4 Yb 1 / 4 Lu 1 / 4 )2Si2O7, denoted as 4-HERED).

[0072] Performance testing:

[0073] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (4-HERED) in this embodiment is shown below. Figure 3 As shown.

[0074] Depend on Figure 3 It can be seen that the high-entropy rare earth silicate ceramic nanopowder in this embodiment has a single β-RE2Si2O7 structure, and no other impurity phases were found.

[0075] Furthermore, SEM and STEM-EDS elemental distribution tests revealed that the high-entropy rare-earth silicate ceramic nanopowder in this embodiment has an irregular particle morphology with an average particle size of approximately 70 nm. The distribution of each metal element is uniform, with no obvious segregation.

[0076] Example 5:

[0077] A high-entropy rare-earth silicate ceramic nanopowder is prepared by the following method:

[0078] 1) Dissolve 0.2298g of Sc2O3 powder, 0.5812g of Sm2O3 powder, 0.6042g of Gd2O3 powder, 0.6217g of Dy2O3 powder, 0.6568g of Yb2O3 powder and 0.6632g of Lu2O3 powder in 80mL of boiling dilute nitric acid solution (mass fraction of 32%) to prepare a rare earth salt solution. Then add 1.6037g of urea and 1.2978g of silica powder, and stir at 100℃ (3h~5h) until a homogeneous viscous gel is formed.

[0079] 2) After loading the gel into a crucible, place it in a muffle furnace and ignite it at 500°C for 5 minutes to obtain a loosely structured foam-like precursor. Grind it for 25 minutes to obtain the precursor powder.

[0080] 3) The precursor powder is placed in a muffle furnace, and the temperature is raised from room temperature to 1300℃ at a rate of 7℃ / min. It is then held at this temperature for 2.5 hours and cooled to room temperature in the furnace to obtain high-entropy rare-earth silicate ceramic nanopowder (hexa-membered high-entropy rare-earth disilicate (Sc)). 1 / 6 Sm 1 / 6 Gd 1 / 6 Dy 1 / 6 Yb 1 / 6 Lu 1 / 6 )2Si2O7, denoted as 6-HERED).

[0081] Performance testing:

[0082] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (6-HERED) in this embodiment is shown below. Figure 3 As shown.

[0083] Depend on Figure 3 It can be seen that the high-entropy rare earth silicate ceramic nanopowder in this embodiment has a single β-RE2Si2O7 structure, and no other impurity phases were found.

[0084] Furthermore, SEM and STEM-EDS energy dispersive spectroscopy elemental distribution tests revealed that the high-entropy rare-earth silicate ceramic nanopowder in this embodiment has an irregular particle morphology with an average particle size of approximately 80 nm. The distribution of each metal element is uniform, and there is no segregation or enrichment phenomenon.

[0085] Example 6:

[0086] A high-entropy rare-earth silicate ceramic nanopowder is prepared by the following method:

[0087] 1) Dissolve 0.2823g of Y2O3 powder, 0.4531g of Gd2O3 powder, 0.4662g of Dy2O3 powder, 0.4723g of Ho2O3 powder, 0.4781g of Er2O3 powder, 0.4823g of Tm2O3 powder, 0.4926g of Yb2O3 powder and 0.4974g of Lu2O3 powder in 100mL of boiled dilute hydrochloric acid solution (mass fraction of 20%) to prepare a rare earth salt solution. Then add 1.6642g of urea and 1.3218g of silica powder, and stir at 120℃ (3h~5h) until a homogeneous viscous gel is formed.

[0088] 2) After loading the gel into a crucible, place it in a muffle furnace and ignite it at 600°C for 6 minutes to obtain a loosely structured foam-like precursor. Grind it for 30 minutes to obtain the precursor powder.

[0089] 3) Place the precursor powder in a muffle furnace, first control the heating rate to rise from room temperature to 1350℃ at 7℃ / min, then hold for 3 hours, and then cool with the furnace to room temperature to obtain high-entropy rare earth silicate ceramic nanopowder (octagonal high-entropy rare earth bissilicate (Y)). 1 / 8 Gd 1 / 8 Dy 1 / 8 Ho 1 / 8 Er 1 / 8 Tm 1 / 8 Yb 1 / 8 Lu 1 / 8 )2Si2O7, denoted as 8-HERED).

[0090] Performance testing:

[0091] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (8-HERED) in this embodiment is shown below. Figure 3 As shown.

[0092] Depend on Figure 3 It can be seen that the high-entropy rare earth silicate ceramic nanopowder in this embodiment has a single β-RE2Si2O7 structure, and no other impurity phases were found.

[0093] Furthermore, SEM and STEM-EDS energy dispersive spectroscopy elemental distribution tests revealed that the high-entropy rare-earth silicate ceramic nanopowder in this embodiment has an irregular particle morphology with an average particle size of approximately 80 nm. The distribution of each metal element is uniform, and there is no segregation or enrichment phenomenon.

[0094] Comparative Example 1:

[0095] A high-entropy rare-earth silicate ceramic nanopowder (denoted as Sample-1) is exactly the same as Example 1, except that the amount of silica powder in step 1) is adjusted from "0.5708g" to "0.6008g" (that is, the ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of silicon atoms in the silica powder is adjusted to 1:0.50).

[0096] Performance testing:

[0097] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (Sample-1) in this comparative example is shown below. Figure 4 As shown.

[0098] Depend on Figure 4 It can be seen that when the ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of silicon atoms in the silica powder is adjusted to 1:0.50, the powder prepared contains a disilicate impurity phase and the product purity is not high. The reason is that the reaction Gibbs free energy of disilicate is lower, and it is easier to form a disilicate phase. Appropriately reducing the amount of silica powder can suppress the formation of the disilicate phase.

[0099] Comparative Example 2:

[0100] A high-entropy rare-earth silicate ceramic nanopowder (denoted as Sample-2) is exactly the same as Example 1, except that the calcination temperature in step 3) is adjusted from "1250℃" to "1200℃".

[0101] Performance testing:

[0102] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (Sample-2) in this comparative example is shown below. Figure 4 As shown.

[0103] Depend on Figure 4 It can be seen that when the calcination temperature is 1200℃, the powder obtained is mainly RE2O3 phase, indicating that the provided temperature is insufficient and cannot provide enough energy for the formation of X2-RE2SiO5 phase. Increasing the temperature can promote the reaction.

[0104] Comparative Example 3:

[0105] A high-entropy rare-earth silicate ceramic nanopowder (denoted as Sample-3) is exactly the same as Example 1, except that the particle size of the silica powder in step 1) is adjusted from "40nm~60nm" to "1μm~3μm" during preparation.

[0106] Performance testing:

[0107] When the particle size of the raw silica powder is adjusted to 1μm to 3μm, the resulting powder has a large particle size with an average particle size of about 2μm. This is because high-entropy silicates mainly grow on the surface of silica powder, and the particle size of the product depends on the initial particle size of the raw silica powder. When the initial particle size of the raw silica powder is large, the particle size of the high-entropy silicate powder will also be relatively large.

[0108] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing high-entropy rare-earth silicate ceramic nanopowder, characterized in that, Includes the following steps: 1) A rare earth oxide powder is dissolved in an acid solution to prepare a rare earth salt solution. The rare earth oxide powder is composed of at least four of the following: Sc2O3 powder, Y2O3 powder, Sm2O3 powder, Eu2O3 powder, Gd2O3 powder, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder, and Lu2O3 powder. Urea and silica powder are then added, and a gelation reaction is carried out to obtain a gel. 2) The gel is ignited for combustion synthesis, then ground to obtain precursor powder; 3) The precursor powder is calcined to obtain high-entropy rare earth silicate ceramic nanopowder. Step 1) The particle size of the silica powder is 40nm to 60nm; Step 1) The ratio of the total molar amount of the rare earth oxide powder to the molar amount of urea is 1:2.50 to 2.75; Step 1) The ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of silicon atoms in the silica powder is 1:0.4-0.5 or 1:1.05-1.15, and is not 1:0.5; Step 1) The gelation reaction is carried out at a temperature of 80℃~120℃ for a reaction time of 3h~5h; Step 2) The ignition temperature for combustion synthesis is 400℃~600℃, and the synthesis time is 3min~10min; Step 3) The specific operation of calcination is as follows: first, control the heating rate to 6℃ / min~8℃ / min to raise the temperature from room temperature to 1250℃~1350℃, then keep it at that temperature for 0.5h~3h, and then cool it down to room temperature with the furnace.

2. The preparation method according to claim 1, characterized in that: Step 1) The rare earth oxide powder is composed of at least four of the following powders in equimolar ratio: Sc2O3 powder, Y2O3 powder, Sm2O3 powder, Eu2O3 powder, Gd2O3 powder, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder, and Lu2O3 powder.

3. The preparation method according to claim 1, characterized in that: The particle size of the rare earth oxide powder in step 1) is 1μm to 3μm and the purity is ≥99.9%; the purity of the urea in step 1) is analytical grade; the purity of the silica powder in step 1) is ≥99.9%.

4. A high-entropy rare-earth silicate ceramic nanopowder, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 3.

5. The high-entropy rare-earth silicate ceramic nanopowder according to claim 4, characterized in that: The average particle size of the high-entropy rare earth silicate ceramic nanopowder is 60 nm to 80 nm.

6. An environmental barrier coating, characterized in that, It includes the high-entropy rare-earth silicate ceramic nanopowder as described in claim 4 or 5.

7. An aerospace engine, characterized in that, The surface of the hot-end component is covered with the environmental barrier coating as described in claim 6.

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