High-entropy rare earth silicate ceramic nanopowder, method for preparing same and use thereof

Abstract

The application discloses high-entropy rare earth silicate ceramic nano powder and a preparation method and application thereof. The preparation method of the high-entropy rare earth silicate ceramic nano powder comprises the following steps: 1) dissolving rare earth oxide powder in an acid solution to prepare a rare earth salt solution; 2) mixing the rare earth salt solution and a sodium silicate solution, adding ammonia water to perform chemical co-precipitation, then performing standing and aging, and then taking the precipitate to perform drying to obtain a precursor powder; and 3) placing the precursor powder under the condition that the temperature is 1100 DEG C to 1200 DEG C to perform calcination. The high-entropy rare earth silicate ceramic nano powder has excellent characteristics such as small particle size, uniform element distribution, large component space and no impurity phase, and the preparation method has the advantages of low synthesis temperature, simple equipment, simple and controllable process, low industrialization cost and the like, is suitable for being used on a hot end part of an aerospace engine and has a very wide application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of high-entropy ceramics, in particular to a high-entropy rare earth disilicate ceramic nano powder and a preparation method and application thereof. BACKGROUND

[0002] High-entropy oxides are considered to be inorganic compound solid solutions, one or more Wyckoff sites of which are occupied by four or more elements, and the proportion of each element is 5 at.% to 35 at.%. Due to the unlimited possibilities of composition design and performance control, high-entropy oxides have attracted extensive attention from researchers. So far, various high-entropy oxide systems including high-entropy rock salt type oxides, high-entropy spinel type oxides, high-entropy perovskite type oxides, high-entropy rare earth disilicate oxides and the like have been developed.

[0003] High-entropy rare earth disilicates have excellent compatibility with silicon-based ceramics, good high-temperature phase stability and excellent corrosion resistance, and are considered to be the best candidate material for the next generation of environmental barrier coatings, and have a very broad application prospect in the hot end parts of aerospace engines. At present, there are few reports on the synthesis method of high-entropy rare earth disilicate ceramic powder, and the synthesis methods thereof mainly include solid phase reaction method and sol-gel method. The solid phase reaction method (for example: (Er 0.25 Tm 0.25 Yb 0.25 Lu 0.25 )2Si2O7 environmental barrier coating material subjected to water vapor and molten calcium-magnesium-aluminosilicate(CMAS), Luchao Sun, Yixiu Luo, Zhilin Tian, Tiefeng Du, Xiaomin Ren, Jialin Li, Wanpeng Hu, Jie Zhang, Jingyang Wang. Corrosion Science, 175 (2020): 108881) has the advantages of low cost, large output and simple preparation process, and is the most commonly used method for synthesizing high-entropy rare earth disilicate ceramic powder at present. However, this method has problems such as high synthesis temperature (≥1550℃), coarse powder particle size (30-40 microns), uneven element distribution, impurity phase, small component space and the like, which seriously limit the development and application of high-performance high-entropy rare earth disilicate ceramics. The sol-gel method (for example: Preparation and corrosion resistance of high-entropy disilicate(Y 0.25 Yb0.25 Er 0.25 Sc 0.25 )2Si2O7ceramics,Xu Wang,Minghao Cheng,Guozheng Xiao,Chao Wang,Ruiqing Qiao,FanZhang,Yu Bai,Yizhuo Li,Yusheng Wu,Zhanjie Wang.Corrosion Science,192(2021):109786)Tetraethyl orthosilicate (TEOS) is usually chosen as the silicon source. However, TEOS has a certain degree of toxicity and cannot be completely and uniformly mixed with the raw materials. The resulting powder has a large particle size (5μm~30μm). Furthermore, the sol-gel method cannot prepare high-entropy rare earth monosilicate powders, which are difficult to synthesize, thus greatly limiting its application.

[0004] Therefore, it is of great significance to develop a method for preparing high-entropy rare-earth silicate ceramic powder with low synthesis temperature, simple equipment, simple and controllable process, and low industrialization cost, 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 a high-entropy rare-earth silicate ceramic nanopowder, its preparation method, and its application.

[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) Dissolve rare earth oxide powder in an acid 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 to obtain a rare earth salt solution.

[0009] 2) Mix rare earth salt solution and sodium silicate solution, add ammonia water for chemical co-precipitation, let stand and age, and then take the precipitate and dry it to obtain precursor powder.

[0010] 3) The precursor powder is calcined at a temperature of 1100℃~1200℃ 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 Sc2O3 powder, Y2O3 powder, Sm2O3 powder, Eu2O3 powder, Gd2O3 powder, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder, and Lu2O3 powder in an equimolar ratio.

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

[0013] Preferably, the sodium silicate solution in step 2) is prepared by dissolving Na2SiO3·9H2O in deionized water.

[0014] Preferably, the purity of the Na2SiO3·9H2O is analytically pure.

[0015] Preferably, the ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of Si atoms in the sodium silicate solution in step 2) is 1:0.40-0.45 (for preparing high-entropy rare earth monosilicate ceramic nano-powder), or the ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of Si atoms in the sodium silicate solution in step 2) is 1:1.0-1.2 (for preparing high-entropy rare earth disilicate ceramic nano-powder).

[0016] Preferably, the chemical co-precipitation in step 2) is carried out at a pH value of 7-8 (for preparing high-entropy rare earth monosilicate ceramic nano-powder), or the chemical co-precipitation in step 2) is carried out at a pH value of 9-10 (for preparing high-entropy rare earth disilicate ceramic nano-powder).

[0017] Preferably, the mixing mode in step 2) is stirring, and the stirring time is 10-30 min.

[0018] Preferably, the standing and aging time in step 2) is 12-24 h.

[0019] Preferably, the precipitate in step 2) is separated from the reaction solution by suction filtration.

[0020] Preferably, the drying in step 2) is carried out at a temperature of 60-80℃, and the drying time is 6-8 h.

[0021] Preferably, the calcination in step 3) is carried out by first controlling the heating rate to 6-8℃ / min to raise the temperature from room temperature (25℃±5℃) to 1100-1200℃, then maintaining the temperature for 2-4 h, and then cooling the furnace to room temperature.

[0022] A high-entropy rare earth silicate ceramic nano-powder prepared by the above method.

[0023] Preferably, the average particle size of the high-entropy rare earth silicate ceramic nanopowder is 100-200 nm.

[0024] Preferably, the high-entropy rare earth silicate ceramic nanopowder is uniform in element distribution and free of impurity phases.

[0025] An environmental barrier coating layer comprising the high-entropy rare earth silicate ceramic nanopowder.

[0026] An aerospace engine, the surface of the hot end part of which is covered with the environmental barrier coating layer.

[0027] The high-entropy rare earth silicate ceramic nanopowder has the advantages of small particle size (100-200 nm), uniform element distribution, large component space, and absence of impurity phases, and the preparation method has the advantages of low synthesis temperature (1100-1200 °C), simple equipment, simple and controllable process, and low industrialization cost (the silicon source is non-toxic and inexpensive), and is suitable for use on the hot end part of an aerospace engine, thus having a very broad application prospect.

[0028] Specifically:

[0029] 1) The high-entropy rare earth silicate ceramic nanopowder preparation method can realize atomic-level mixing of raw materials, which is conducive to the synthesis of the powder and has the advantages of low synthesis temperature (1100-1200 °C), simple equipment, simple and controllable process, and low industrialization cost;

[0030] 2) The silicon source (sodium silicate) used in the high-entropy rare earth silicate ceramic nanopowder preparation method is non-toxic and inexpensive, and the rare earth source and the silicon source can be uniformly mixed and reacted by the chemical co-precipitation method, thereby realizing the preparation of the nanopowder with uniform composition;

[0031] 3) The high-entropy rare earth silicate ceramic powder preparation method can prepare high-entropy rare earth monosilicate nanopowder (X2-RE2SiO5 structure) and high-entropy rare earth disilicate nanopowder (β-RE2Si2O7 structure) with a large component space, and can prepare the high-entropy rare earth monosilicate nanopowder which is difficult to synthesize by adjusting only the process parameters;

[0032] 4) The high-entropy rare earth silicate ceramic nanopowder has the advantages of small particle size (100-200 nm), uniform element distribution, and absence of impurity phases, and the morphology of the powder is easy to control, which is conducive to subsequent sintering. BRIEF DESCRIPTION OF DRAWINGS

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

[0034] Figure 2 SEM image and STEM-EDS energy spectrum element distribution diagram of the high-entropy rare earth silicate ceramic nanopowder of Example 1.

[0035] Figure 3 XRD diagram of the high-entropy rare earth silicate ceramic nanopowder of Examples 4-6.

[0036] Figure 4 XRD diagram of the high-entropy rare earth silicate ceramic nanopowder of Comparative Examples 1-3. DETAILED DESCRIPTION

[0037] The application will be further explained and described with reference to specific examples.

[0038] The particle size of the 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 1-4 is 1-3 μm, and the purity is ≥99.9%.

[0039] The purity of Na2SiO3·9H2O in Examples 1-6 and Comparative Examples 1-3 is analytically pure.

[0040] Example 1:

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

[0042] 1) 1.9126 g of Er2O3 powder, 1.9293 g of Ho2O3 powder, 1.9705 g of Yb2O3 powder and 1.9897 g of Lu2O3 powder are dissolved in 80 mL of boiling dilute nitric acid solution (mass fraction 32%) to obtain a rare earth nitrate solution; 5.1155 g of Na2SiO3·9H2O is dissolved in 50 mL of deionized water to obtain a sodium silicate solution;

[0043] 2) The rare earth nitrate solution and the sodium silicate solution are mixed (the ratio of the total molar amount of rare earth atoms in the rare earth nitrate solution to the molar amount of Si atoms in the sodium silicate solution is 1:0.45), stirred for 10 min to form a clear transparent uniform solution, then ammonia water (mass fraction 25%) is slowly added to adjust the pH value of the reaction solution to 7-8 for chemical co-precipitation, then left to stand for 12 h, then filtered and washed with water for 3 times, then the precipitate is dried at a temperature of 60°C to obtain a precursor powder;

[0044] 3) Place the precursor powder in a muffle furnace, first control the heating rate to rise from room temperature to 1100℃ 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 monosilicate (Er)). 1 / 4 Ho 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 and the STEM-EDS energy dispersive spectroscopy (EDS) elemental distribution map are as follows: Figure 2 As shown.

[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 2 It can be seen that the average particle size of the high-entropy rare earth silicate ceramic nanopowder in this embodiment is about 150 nm, and the distribution of each metal element is uniform with no obvious segregation.

[0049] Example 2:

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

[0051] 1) Dissolve 0.9032g of Y2O3 powder, 1.3949g of Sm2O3 powder, 1.5301g of Er2O3 powder, 1.5434g of Tm2O3 powder, and 1.5764g of Yb2O3 powder in 80mL of boiled dilute hydrochloric acid solution (mass fraction 20%) to obtain a rare earth chloride solution; dissolve 4.5472g of Na2SiO3·9H2O in 50mL of deionized water to obtain a sodium silicate solution;

[0052] 2) Mix the rare earth chloride solution and sodium silicate solution (the ratio of the total molar amount of rare earth atoms in the rare earth chloride solution to the molar amount of Si atoms in the sodium silicate solution is 1:0.40), stir for 20 min to form a clear and transparent homogeneous solution, then slowly add ammonia water (mass fraction of 25%) to adjust the pH value of the reaction solution to 7-8 for chemical coprecipitation, then let it stand for 18 h, then filter and wash with water 4 times, then take the precipitate and dry it at a temperature of 70℃ 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 1200℃ at 8℃ / min, then hold for 3 hours, and then cool with the furnace to room temperature to obtain high-entropy rare earth silicate ceramic nanopowder (pentabyte high-entropy rare earth monosilicate (Y)). 1 / 5 Sm 1 / 5 Er 1 / 5 Tm 1 / 5 Yb 1 / 5 )2SiO5, denoted as 5-HEREM).

[0054] Performance testing:

[0055] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (5-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 180 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 0.4597g of Sc2O3 powder, 1.2433g of Dy2O3 powder, 1.2595g of Ho2O3 powder, 1.2751g of Er2O3 powder, 1.3137g of Yb2O3 powder, and 1.3265g of Lu2O3 powder in 80mL of boiling dilute nitric acid solution (mass fraction 32%) to obtain a rare earth nitrate solution; dissolve 4.5472g of Na2SiO3·9H2O in 50mL of deionized water to obtain a sodium silicate solution;

[0061] 2) Mix rare earth nitrate solution and sodium silicate solution (the ratio of the total molar amount of rare earth atoms in rare earth nitrate solution to the molar amount of Si atoms in sodium silicate solution is 1:0.40), stir for 30 min to form a clear and transparent homogeneous solution, then slowly add ammonia water (mass fraction of 25%) to adjust the pH value of the reaction solution to 7-8 for chemical coprecipitation, then let it stand for 12 h, then filter and wash with water 5 times, then take the precipitate and dry it at a temperature of 80℃ to obtain precursor powder;

[0062] 3) Place the precursor powder in a muffle furnace, first control the heating rate to rise from room temperature to 1200℃ at 8℃ / min, then hold for 4 hours, 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 Dy 1 / 6 Ho 1 / 6 Er 1 / 6 Yb 1 / 6 Lu 1 / 6 )2SiO5, denoted as 6-HEREM).

[0063] Performance testing:

[0064] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (6-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 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 150 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 1.7436g of Sm2O3 powder, 1.8125g of Gd2O3 powder, 1.9126g of Er2O3 powder and 1.9897g of Lu2O3 powder in 120mL of boiling dilute nitric acid solution (mass fraction 32%) to obtain a rare earth nitrate solution; dissolve 11.3679g of Na2SiO3·9H2O in 75mL of deionized water to obtain a sodium silicate solution;

[0070] 2) Mix the rare earth nitrate solution and sodium silicate solution (the ratio of the total molar amount of rare earth atoms in the rare earth nitrate solution to the molar amount of Si atoms in the sodium silicate solution is 1:1.0), stir for 10 min to form a clear and transparent homogeneous solution, then slowly add ammonia water (mass fraction of 32%) to adjust the pH value of the reaction solution to 9-10 for chemical coprecipitation, then let it stand for 12 h, then filter and wash with water 3 times, then take the precipitate and dry it at a temperature of 60℃ to obtain the precursor powder;

[0071] 3) Put the precursor powder into a muffle furnace, control the heating rate at 8℃ / min from room temperature to 1100℃, then keep the temperature for 2h, and then cool down to room temperature with the furnace, to obtain the high-entropy rare earth silicate ceramic nano-powder (quaternary high-entropy rare earth double-silicate (Sm 1 / 4 Gd 1 / 4 Er 1 / 4 Lu 1 / 4 )2Si2O7, denoted as 4-HERED).

[0072] Performance test:

[0073] The XRD pattern of the high-entropy rare earth silicate ceramic nano-powder (4-HERED) of the present example is shown in FIG. 1. Figure 3

[0074] As can be seen from FIG. 1, the high-entropy rare earth silicate ceramic nano-powder of the present example is of a single β-RE2Si2O7structure, and no other impurity phase is found. Figure 3 In addition, it is found through SEM and STEM-EDS energy spectrum element distribution test that the particle morphology of the high-entropy rare earth silicate ceramic nano-powder of the present example is irregular, the average particle size is about 120nm, and each metal element is uniformly distributed without obvious segregation.

[0075] Example 5:

[0076] A high-entropy rare earth silicate ceramic nano-powder is prepared by the following method:

[0077] 1) Dissolve 0.9032g of Y2O3 powder, 1.4077g of Eu2O3 powder, 1.4920g of Dy2O3 powder, 1.5114g of Ho2O3 powder and 1.5917g of Lu2O3 powder in 120mL of boiling dilute hydrochloric acid solution (mass fraction of 20%), to obtain a rare earth chloride solution; dissolve 12.5047g of Na2SiO3·9H2O in 75mL of deionized water, to obtain a sodium silicate solution;

[0078] 2) Mix the rare earth chloride solution and the sodium silicate solution (the ratio of the total molar amount of rare earth atoms in the rare earth chloride solution to the molar amount of Si atoms in the sodium silicate solution is 1:1.1), stir for 20min to form a clear and transparent uniform solution, then slowly add ammonia water (mass fraction of 25%) to adjust the pH value of the reaction solution to 9-10 for chemical co-precipitation, then stand for aging for 18h, then extract and wash with water for 4 times, then take the precipitate to be dried at a temperature of 70℃, to obtain a precursor powder;

[0079]

[0080] ​​3) Put the precursor powder into a muffle furnace, control the heating rate at 8℃ / min from room temperature to 1200℃, then keep the temperature for 3h, and then cool down to room temperature with the furnace, to obtain the high-entropy rare earth silicate ceramic nano-powder (a five-element high-entropy rare earth double-silicate (Y 1 / 5 Eu 1 / 5 Dy 1 / 5 Ho 1 / 5 Lu 1 / 5 )2Si2O7, denoted as 5-HERED.

[0081] Performance test:

[0082] The XRD pattern of the high-entropy rare earth silicate ceramic nano-powder (5-HERED) of the present example is shown in FIG. 1. Figure 3

[0083] As can be seen from FIG. 1, the high-entropy rare earth silicate ceramic nano-powder of the present example is of a single β-RE2Si2O7structure, and no other impurity phase is found. Figure 3 In addition, it is found through SEM and STEM-EDS energy spectrum element distribution test that the particle morphology of the high-entropy rare earth silicate ceramic nano-powder of the present example is irregular, the average particle size is about 160nm, and each metal element is uniformly distributed without segregation and enrichment phenomenon.

[0084] Example 6:

[0085] A high-entropy rare earth silicate ceramic nano-powder is prepared by the following method:

[0086] 1) Dissolve 0.4597g of Sc2O3powder, 1.1731g of Eu2O3powder, 1.2083g of Gd2O3powder, 1.2433g of Dy2O3powder, 1.3137g of Yb2O3powder and 1.3265g of Lu2O3powder in 120mL of boiling dilute nitric acid solution (mass fraction of 32%) to obtain a rare earth nitrate solution; dissolve 13.6415g of Na2SiO3·9H2O in 75mL of deionized water to obtain a sodium silicate solution;

[0087] 2) Mix the rare earth nitrate solution and the sodium silicate solution (the ratio of the total molar amount of rare earth atoms in the rare earth nitrate solution to the molar amount of Si atoms in the sodium silicate solution is 1:1.2), stir for 30min to form a clear and transparent uniform solution, then slowly add ammonia water (mass fraction of 25%) to adjust the pH value of the reaction solution to 9-10 for chemical co-precipitation, then stand for aging for 12h, then extract and wash with water for 5 times, then take the precipitate to be dried at a temperature of 80℃, to obtain a precursor powder;

[0088]

[0089] ​​3) Place the precursor powder in a muffle furnace, first control the heating rate to rise from room temperature to 1200℃ at 8℃ / min, then hold at that temperature for 4 hours, and then cool with the furnace to room temperature to obtain high-entropy rare earth silicate ceramic nanopowder (hexa-membered high-entropy rare earth bis-silicate (Sc)). 1 / 6 Eu 1 / 6 Gd 1 / 6 Dy 1 / 6 Yb 1 / 6 Lu 1 / 6 )2Si2O7, denoted as 6-HERED).

[0090] Performance testing:

[0091] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (6-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 180 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 is prepared in exactly the same way as in Example 1, except that the "5.1155g of Na2SiO3·9H2O" in step 1) is adjusted to "5.6839g of Na2SiO3·9H2O" (that is, the ratio of the total molar amount of rare earth atoms in the rare earth nitrate solution to the molar amount of Si atoms in the sodium silicate solution is adjusted to 1:0.50). The high-entropy rare-earth silicate ceramic nanopowder prepared is referred to as Sample-1.

[0096] Performance testing:

[0097] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (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 nitrate solution to the molar amount of Si atoms in the sodium silicate solution is 1:0.50, the prepared powder 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. An appropriate amount of Na2SiO3 can inhibit the formation of the disilicate phase.

[0099] Comparative Example 2:

[0100] A high-entropy rare-earth silicate ceramic nanopowder is prepared in the same way as in Example 1, except that the step 2) is changed from "adjusting the pH of the reaction solution to 7-8" to "adjusting the pH of the reaction solution to 9-10". (The high-entropy rare-earth silicate ceramic nanopowder prepared is referred to as Sample-2).

[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 pH of the reaction solution is adjusted to 9-10, the prepared powder still contains a silicate impurity phase, and the product purity is not high. The reason is that lowering the pH value increases the OH- ions in the solution. - The content of [a certain substance] decreases accordingly, which can also inhibit the formation of the disilicate phase.

[0104] Based on Comparative Examples 1 and 2, it can be seen that the SiO3 in the reaction solution... 2- Ion concentration and OH - Ion concentration affects the phase composition of the synthesized powder, with bissilicates having a greater impact on the SiO3 content in the reaction solution. 2- Ion concentration and OH - Ion concentration is quite sensitive, reducing SiO3 2- and OH - The content of all of them can inhibit the formation of the disilicate phase.

[0105] Comparative Example 3:

[0106] A high-entropy rare-earth silicate ceramic nanopowder is prepared in exactly the same way as in Example 1, except that the calcination temperature in step 3) is adjusted from "1100℃" to "1000℃". (The high-entropy rare-earth silicate ceramic nanopowder prepared is referred to as Sample-3).

[0107] Performance testing:

[0108] The XRD pattern of the high-entropy rare-earth silicate ceramic nanopowder (Sample-3) in this comparative example is shown below. Figure 4 As shown.

[0109] Depend on Figure 4It can be seen that when the calcination temperature is 1000℃, the prepared powder is mainly X1-RE2SiO5 phase, which indicates that the provided temperature is not enough to provide sufficient energy for the formation of X2-RE2SiO5 phase, and increasing the temperature can make the X1 phase transform into the X2 phase.

[0110] Comparative Example 4:

[0111] A high-entropy rare earth silicate ceramic nano powder, except that "5.1155g of Na2SiO3·9H2O" in step 1) is replaced by "30mL of TEOS solution with a concentration of 4mol / L" during preparation, the rest is exactly the same as Example 1 (the prepared high-entropy rare earth silicate ceramic nano powder is recorded as Sample-4).

[0112] After testing (XRD, SEM and STEM-EDS), when the silicon source is replaced by TEOS, the prepared powder contains more double silicate impurities, the product particle size is coarse, the composition is not uniform, and there is serious composition segregation, because: TEOS cannot be fully and uniformly mixed with the solution, and using Na2SiO3 as the silicon source is beneficial to prepare a nano powder with uniform composition.

[0113] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for preparing high-entropy rare-earth silicate ceramic nanopowder, characterized in that, Includes the following steps: 1) Dissolve rare earth oxide powder in an acid solution. 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, to obtain a rare earth salt solution. 2) Mix rare earth salt solution and sodium silicate solution, add ammonia water for chemical co-precipitation, let stand and age, and then take the precipitate and dry it to obtain precursor powder; 3) The precursor powder is calcined at a temperature of 1100℃~1200℃ to obtain high-entropy rare earth silicate ceramic nanopowder. In step 2), the ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of Si atoms in the sodium silicate solution is 1:0.40~0.45; in step 2), the chemical coprecipitation is carried out under the condition that the pH value of the reaction solution is 7~8. In step 2), the ratio of the total molar amount of rare earth atoms in the rare earth salt solution to the molar amount of Si atoms in the sodium silicate solution is 1:1.0~1.2; the chemical coprecipitation in step 2) is carried out under the condition that the pH value of the reaction solution is 9~10.

2. The preparation method according to claim 1, characterized in that: Step 1) The rare earth oxide powder has a particle size of 1μm~3μm and a purity of ≥99.9%.

3. The preparation method according to claim 1, characterized in that: 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 1100℃~1200℃, then keep it at that temperature for 2h~4h, and then cool it down to room temperature with the furnace.

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 100nm~200nm.

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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