High-entropy rare earth silicate ceramic powder, preparation method and application thereof

Abstract

The application discloses a high-entropy rare earth silicate ceramic powder and a preparation method and application thereof. The preparation method of the high-entropy rare earth silicate ceramic powder comprises the following steps: 1) mixing rare earth oxide powder, SiO2 powder, LiCl and KCl and grinding to obtain a mixed powder; and 2) calcining the mixed powder under the condition that the temperature is 700 DEG C to 900 DEG C, and then performing water washing and drying to obtain the high-entropy rare earth silicate ceramic powder. The high-entropy rare earth silicate ceramic powder has the excellent characteristics of high purity, small particle size, uniform element distribution and large component space, and the preparation method has the advantages of short preparation period, low synthesis temperature, small energy consumption and high efficiency, 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] This invention relates to the field of high-entropy ceramics technology, specifically to a high-entropy rare-earth silicate ceramic powder, its preparation method, and its application. Background Technology

[0002] High-entropy oxides refer to oxides with a single structure prepared by mutual solid solution of multiple metal or non-metal oxides in equimolar or near-molar ratios. They offer limitless possibilities for compositional design and performance control, attracting widespread attention from researchers. To date, various high-entropy oxide systems, including high-entropy rock salt oxides, high-entropy spinel oxides, high-entropy perovskite oxides, and high-entropy rare-earth silicate oxides, have been developed. High-entropy rare-earth silicates possess excellent physicochemical compatibility with silicon-based ceramics, good high-temperature phase stability, and excellent corrosion resistance, making them considered the best candidate materials for next-generation environmental barrier coatings and showing broad application prospects in hot-end components of aerospace engines.

[0003] Currently, there are few reports on the synthesis methods of high-entropy rare-earth silicate ceramic powders. The main synthesis methods include solid-state reaction and sol-gel methods. Solid-state reaction has advantages such as low cost, high yield, and simple preparation process, making it the most commonly used method for synthesizing high-entropy rare-earth silicate ceramic powders. However, it also has problems such as long synthesis cycle (3-4 days), high synthesis temperature (1550℃-1700℃), high energy consumption, and low efficiency. Furthermore, the synthesized powders also suffer from quality issues such as large particle size (30μm-40μm), uneven element distribution, small component space, and the presence of impurities (e.g., Synthesis, microstructures, and corrosion behaviors of multi-components rare-earthsilicates, Wei Liao, Yongqiang Tan, Chaowen Zhu, Zhen Teng, Peng Jia, Haibin Zhang. Ceramics International, 47(2021):32641-32647; (Er 0.25 Tm 0.25 Yb 0.25 Lu 0.25The environmental barrier coating material of 2Si2O7 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 Zhanga, Jingyang Wang. Corrosion Science, 175(2020):108881), ultimately greatly limited the practical application of high-entropy rare earth silicate ceramics.

[0004] Therefore, there is an urgent need to develop a rapid, low-temperature, and low-cost method for preparing high-entropy rare-earth silicate ceramic powders, and to produce high-purity, fine-particle-size, uniformly distributed elemental powders with large component space. Summary of the Invention

[0005] The purpose of this invention is to provide a high-entropy rare-earth silicate ceramic powder, 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 powder includes the following steps:

[0008] 1) Mix and grind rare earth oxide powder, SiO2 powder, LiCl and KCl. The rare earth oxide powder is composed of at least four of the following: Sc2O3 powder, Y2O3 powder, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder and Lu2O3 powder, to obtain a mixed powder.

[0009] 2) The mixed powder is calcined at a temperature of 700℃~900℃, then washed with water and dried to obtain high entropy rare earth silicate ceramic powder.

[0010] 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, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder, and Lu2O3 powder.

[0011] Preferably, the rare earth oxide powder in step 1) has a particle size of 1μm to 3μm and a purity of ≥99.9%.

[0012] Preferably, the SiO2 powder in step 1) has a particle size of 1μm to 3μm and a purity of ≥99.9%.

[0013] Preferably, the ratio of the total mass of the rare earth oxide powder and SiO2 powder in step 1) to the total mass of LiCl and KCl is 1:8 to 10.

[0014] Preferably, the mass ratio of LiCl to KCl in step 1) is 1:1.2 to 1.4.

[0015] Preferably, the ratio of the total molar amount of rare earth atoms in the rare earth oxide powder to the molar amount of Si atoms in the SiO2 powder in step 1) is 1:1.7 to 1.9. A small amount of SiO2 (5% to 15%) can be used to synthesize high-entropy rare earth monosilicate ultrafine powder (X2-RE2SiO5 structure).

[0016] Preferably, the ratio of the total molar amount of rare earth atoms in the rare earth oxide powder to the molar amount of Si atoms in the SiO2 powder in step 1) is 1.1 to 1.2:1. With an excess of 10% to 20% SiO2, high-entropy rare earth disilicate ultrafine powder (β-RE2Si2O7 structure) can be synthesized.

[0017] Preferably, the grinding time in step 1) is not less than 30 minutes.

[0018] More preferably, the grinding time in step 1) is 30 min to 40 min.

[0019] Preferably, the specific operation of calcination in step 2) is as follows: control the heating rate to 6℃ / min~8℃ / min to heat from room temperature to 700℃~900℃, then hold for 2h~4h, and then cool with the furnace to room temperature.

[0020] Preferably, the water washing method in step 2) is ultrasonic washing, and the number of washings is not less than 5 times, with each washing time not less than 60 minutes.

[0021] More preferably, the water washing method in step 2) is ultrasonic washing, the number of washing cycles is 5 to 8, and the washing time for each cycle is 60 to 80 minutes.

[0022] Preferably, the drying in step 2) is carried out at a temperature of 60℃~80℃ for a drying time of not less than 6 hours.

[0023] More preferably, the drying in step 2) is carried out at a temperature of 60℃~80℃ for a drying time of 6h~10h.

[0024] A high-entropy rare-earth silicate ceramic powder is prepared by the above-described method.

[0025] Preferably, the high-entropy rare-earth silicate ceramic powder has an average particle size of 1.2 μm to 1.6 μm and the elements are evenly distributed.

[0026] An aero-engine in which an environmental barrier coating on a hot-end component comprises the aforementioned high-entropy rare-earth silicate ceramic powder.

[0027] The beneficial effects of this invention are: the high-entropy rare earth silicate ceramic powder of this invention has excellent characteristics such as high purity, fine particle size (1.2μm~1.6μm), uniform element distribution, and large component space. Moreover, its preparation method has the advantages of short preparation cycle (1 day to 2 days), low synthesis temperature (700℃~900℃), low energy consumption, and high efficiency. It is suitable for use in hot-end components of aerospace engines and has a very broad application prospect.

[0028] Specifically:

[0029] 1) The preparation process of the high-entropy rare earth silicate ceramic powder of the present invention is simple and does not require pretreatment such as ball milling and sieving of the raw material powder, which greatly shortens the preparation cycle of the powder (1 day to 2 days). Moreover, by using a mixed molten salt medium composed of LiCl and KCl, a sufficient liquid phase environment can be provided for the reaction process, which greatly reduces the synthesis temperature (700℃ to 900℃), resulting in low energy consumption and high efficiency. In addition, the molten salt is easy to separate and can be repeatedly recycled, making it suitable for large-scale industrial production and application.

[0030] 2) The high-entropy rare earth silicate ceramic powder of the present invention has a small particle size (1.2μm~1.6μm), which is significantly lower than the average particle size of high-entropy rare earth silicate ceramic powder prepared by the traditional solid-state reaction method. It also has uniform element distribution and no impurity phase. In addition, the morphology and particle size of the powder are controllable. By controlling the reaction temperature and holding time, ultrafine powder with higher sphericity and better flowability can be obtained.

[0031] 3) The high-entropy rare earth silicate ceramic powder preparation method of the present invention can prepare high-entropy rare earth monosilicate ultrafine powder (X2-RE2SiO5 structure) and high-entropy rare earth disilicate ultrafine powder (β-RE2Si2O7 structure) with a huge component space. Attached Figure Description

[0032] Figure 1 The images show the XRD patterns of the high-entropy rare-earth silicate ceramic powders from Examples 1-3.

[0033] Figure 2 The images show the XRD patterns of the high-entropy rare-earth silicate ceramic powders from Examples 4 to 6.

[0034] Figure 3The images show the SEM image and STEM-EDS elemental distribution diagram of the high-entropy rare-earth silicate ceramic powder in Example 6.

[0035] Figure 4 The images show the XRD patterns of high-entropy rare-earth silicate ceramic powders from Comparative Example 1 and Comparative Example 2.

[0036] Figure 5 The image shows the SEM image of the high-entropy rare-earth silicate ceramic powder in Comparative Example 4. 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, Dy2O3 powder, Ho2O3 powder, Er2O3 powder, Tm2O3 powder, Yb2O3 powder and Lu2O3 powder in Examples 1-6 and Comparative Examples 1-4 are all 1μm to 3μm, and the purity is ≥99.9%.

[0039] The SiO2 powder in Examples 1-6 and Comparative Examples 1-4 had a particle size of 1 μm to 3 μm and a purity of ≥99.99%.

[0040] The CaCl2, NaCl, LiCl, and KCl in Examples 1-6 and Comparative Examples 1-4 were all of analytical grade.

[0041] Example 1:

[0042] A high-entropy rare-earth silicate ceramic powder is prepared by the following steps:

[0043] 1) Add 0.1976g of Sc2O3 powder, 0.3235g of Y2O3 powder, 0.5646g of Yb2O3 powder, 0.5701g of Lu2O3 powder, 0.2927g of SiO2 powder (i.e., a small amount of SiO2, 15%), 8.7681g of LiCl and 10.7154g of KCl to an agate mortar and grind by hand for 30 minutes to obtain a mixed powder;

[0044] 2) After pouring the mixed powder into a crucible, place it in a muffle furnace and raise the temperature from room temperature to 800℃ at a rate of 8℃ / min. Hold the temperature for 3 hours, then cool it to room temperature with the furnace. Ultrasonically wash the powder five times with deionized water, each time for 60 minutes. Then dry it in an oven at 70℃ for 6 hours to obtain high-entropy rare-earth silicate ceramic powder (quaternary high-entropy rare-earth monosilicate (Sc)). 1 / 4 Y 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 powder (4-HEREM) in this embodiment is shown below. Figure 1 As shown.

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

[0048] Furthermore, elemental distribution tests using scanning electron microscopy (SEM) and STEM-EDS revealed that the microstructure of the high-entropy rare-earth silicate ceramic powder in this embodiment is mainly composed of spherical particles with an average particle size of approximately 1.5 μm. The distribution of each metal element is uniform, with no obvious segregation.

[0049] Example 2:

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

[0051] 1) Add 0.1891g of Ho2O3 powder, 0.3203g of Er2O3 powder, 0.3231g of Tm2O3 powder, 0.3300g of Yb2O3 powder, 0.3332g of Lu2O3 powder, 0.3396g of SiO2 powder (i.e., a small amount of SiO2, 10%), 8.2586g of LiCl and 10.0928g of KCl to an agate mortar and grind by hand for 35 minutes to obtain a mixed powder;

[0052] 2) After pouring the mixed powder into a crucible, place it in a muffle furnace and raise the temperature from room temperature to 900℃ at a rate of 7℃ / min. Hold the temperature for 3 hours, then cool it to room temperature with the furnace. Ultrasonically wash the powder 6 times with deionized water, each time for 70 minutes. Then dry it in an oven at 80℃ for 8 hours to obtain high-entropy rare-earth silicate ceramic powder (pentabyte high-entropy rare-earth monosilicate (Ho)). 1 / 5 Er 1 / 5 Tm 1 / 5 Yb 1 / 5 Lu 1 / 5 )2SiO5, denoted as 5-HEREM).

[0053] Performance testing:

[0054] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (5-HEREM) in this embodiment is shown below. Figure 1 As shown.

[0055] Depend on Figure 1It can be seen that the high-entropy rare earth silicate ceramic powder in this embodiment has a single X2-RE2SiO5 structure, and no other impurity phases were found.

[0056] Furthermore, SEM and STEM-EDS energy dispersive spectroscopy elemental distribution tests revealed that the microstructure of the high-entropy rare earth silicate ceramic powder in this embodiment is mainly composed of spherical particles with an average particle size of approximately 1.5 μm. The distribution of each metal element is uniform, with no obvious segregation.

[0057] Example 3:

[0058] A high-entropy rare-earth silicate ceramic powder is prepared by the following steps:

[0059] 1) Add 0.1138g of Sc2O3 powder, 0.3078g of Dy2O3 powder, 0.3118g of Ho2O3 powder, 0.3156g of Er2O3 powder, 0.3252g of Yb2O3 powder, 0.3284g of Lu2O3 powder, 0.2826g of SiO2 powder (i.e., a small amount of SiO2, 5%), 8.9336g of LiCl and 10.9177g of KCl to an agate mortar and grind by hand for 40 minutes to obtain a mixed powder;

[0060] 2) After pouring the mixed powder into a crucible, place it in a muffle furnace and raise the temperature from room temperature to 900℃ at a rate of 6℃ / min. Hold the temperature for 4 hours, then cool it to room temperature with the furnace. Ultrasonically wash the powder 8 times with deionized water, each wash lasting 80 minutes. Then dry it in an oven at 80℃ for 10 hours to obtain high-entropy rare-earth silicate ceramic powder (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).

[0061] Performance testing:

[0062] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (6-HEREM) in this embodiment is shown below. Figure 1 As shown.

[0063] Depend on Figure 1 It can be seen that the high-entropy rare earth silicate ceramic powder in this embodiment has a single X2-RE2SiO5 structure, and no other impurity phases were found.

[0064] Furthermore, SEM and STEM-EDS energy dispersive spectroscopy elemental distribution tests revealed that the microstructure of the high-entropy rare earth silicate ceramic powder in this embodiment is mainly composed of spherical particles with an average particle size of approximately 1.6 μm. The distribution of each metal element is uniform, with no obvious segregation.

[0065] Example 4:

[0066] A high-entropy rare-earth silicate ceramic powder is prepared by the following steps:

[0067] 1) Add 0.3748g of Er2O3 powder, 0.3781g of Tm2O3 powder, 0.3862g of Yb2O3 powder, 0.3899g of Lu2O3 powder, 0.5652g of SiO2 powder (i.e., SiO2 in excess of 10%), 9.4244g of LiCl and 11.5715g of KCl to an agate mortar and grind by hand for 30 minutes to obtain a mixed powder;

[0068] 2) After pouring the mixed powder into a crucible, place it in a muffle furnace and raise the temperature from room temperature to 700℃ at a rate of 8℃ / min. Hold the temperature for 2 hours, then cool it to room temperature with the furnace. Ultrasonically wash the powder five times with deionized water, each time for 60 minutes. Then dry it in an oven at 80℃ for 6 hours to obtain high-entropy rare-earth silicate ceramic powder (quaternary high-entropy rare-earth disilicate (Er...)). 1 / 4 Tm 1 / 4 Yb 1 / 4 Lu 1 / 4 )2Si2O7, denoted as 4-HERED).

[0069] Performance testing:

[0070] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (4-HERED) in this embodiment is as follows: Figure 2 As shown.

[0071] Depend on Figure 2 It can be seen that the high-entropy rare earth silicate ceramic powder in this embodiment has a single β-RE2Si2O7 structure, and no other impurity phases were found.

[0072] Furthermore, SEM and STEM-EDS energy dispersive spectroscopy elemental distribution tests revealed that the microstructure of the high-entropy rare earth silicate ceramic powder in this embodiment is mainly composed of spherical particles with an average particle size of approximately 1.2 μm. The distribution of each metal element is uniform, with no obvious segregation.

[0073] Example 5:

[0074] A high-entropy rare-earth silicate ceramic powder is prepared by the following steps:

[0075] 1) Add 0.1299g of Sc2O3 powder, 0.2127g of Y2O3 powder, 0.3560g of Ho2O3 powder, 0.3604g of Er2O3 powder, 0.3749g of Lu2O3 powder, 0.5661g of SiO2 powder (i.e., SiO2 in excess of 15%), 9.0005g of LiCl and 10.9995g of KCl to an agate mortar and grind by hand for 35 minutes to obtain a mixed powder;

[0076] 2) After pouring the mixed powder into a crucible, place it in a muffle furnace and raise the temperature from room temperature to 800℃ at a rate of 7℃ / min. Hold the temperature for 3 hours, then cool it to room temperature with the furnace. Ultrasonically wash the powder five times with deionized water, each time for 60 minutes. Then dry it in an oven at 70℃ for 8 hours to obtain high-entropy rare-earth silicate ceramic powder (pentabyte high-entropy rare-earth disilicate (Sc)). 1 / 5 Y 1 / 5 Ho 1 / 5 Er 1 / 5 Lu 1 / 5 )2Si2O7, denoted as 5-HERED).

[0077] Performance testing:

[0078] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (5-HERED) in this embodiment is as follows: Figure 2 As shown.

[0079] Depend on Figure 2 It can be seen that the high-entropy rare earth silicate ceramic powder in this embodiment has a single β-RE2Si2O7 structure, and no other impurity phases were found.

[0080] Furthermore, SEM and STEM-EDS energy dispersive spectroscopy elemental distribution tests revealed that the microstructure of the high-entropy rare earth silicate ceramic powder in this embodiment is mainly composed of spherical particles with an average particle size of approximately 1.4 μm. The distribution of each metal element is uniform, and there is no segregation or enrichment phenomenon.

[0081] Example 6:

[0082] A high-entropy rare-earth silicate ceramic powder is prepared by the following steps:

[0083] 1) Add 0.2664g of Y2O3 powder, 0.2597g of Dy2O3 powder, 0.2744g of Ho2O3 powder, 0.2771g of Er2O3 powder, 0.1572g of Yb2O3 powder, 0.2631g of Lu2O3 powder, 0.6025g of SiO2 powder (i.e., SiO2 in excess of 20%), 9.4524g of LiCl and 11.5517g of KCl to an agate mortar and grind by hand for 40 minutes to obtain a mixed powder;

[0084] 2) After pouring the mixed powder into a crucible, place it in a muffle furnace and raise the temperature from room temperature to 900℃ at a rate of 6℃ / min. Hold the temperature for 4 hours, then cool it to room temperature with the furnace. Ultrasonically wash the powder five times with deionized water, each time for 60 minutes. Then dry it in an oven at 80℃ for 10 hours to obtain high-entropy rare-earth silicate ceramic powder (hexa-membered high-entropy rare-earth disilicate (Y)). 1 / 6 Dy 1 / 6 Ho 1 / 6 Er 1 / 6 Yb 1 / 6 Lu 1 / 6 )2Si2O7, denoted as 6-HERED).

[0085] Performance testing:

[0086] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (6-HERED) in this embodiment is as follows: Figure 2 As shown, the SEM image and STEM-EDS energy dispersive spectroscopy elemental distribution map are as follows: Figure 3 As shown.

[0087] Depend on Figure 2 It can be seen that the high-entropy rare earth silicate ceramic powder in this embodiment has a single β-RE2Si2O7 structure, and no other impurity phases were found.

[0088] Depend on Figure 3 It can be seen that the microstructure of the high-entropy rare earth silicate ceramic powder in this embodiment is mainly composed of spherical particles with an average particle size of about 1.3 μm. The metal elements are evenly distributed and there is no segregation or enrichment phenomenon.

[0089] Comparative Example 1:

[0090] A high-entropy rare-earth silicate ceramic powder is prepared in exactly the same way as in Example 6, except that "9.4524g of LiCl and 11.5517g of KCl" is replaced with "21.0041g of CaCl2", "21.0041g of NaCl", "10.5021g of K2CO3 and 10.5021g of KCl" or "10.5021g of NaCl and 10.5021g of KCl" (the high-entropy rare-earth silicate ceramic powders prepared are referred to as Sample-1, Sample-2, Sample-3 and Sample-4 respectively).

[0091] Performance testing:

[0092] The XRD pattern of the high-entropy rare-earth silicate ceramic powder in this comparative example is shown below. Figure 4 As shown.

[0093] Depend on Figure 4It can be known that:

[0094] 1) When CaCl2 is used as the molten salt, the powder obtained is Ca2RE2O2(Si2O7) phase (RE represents lanthanide rare earth elements). The reason is that CaCl2 will adsorb water vapor in the air to form hydrated calcium chloride CaCl2·nH2O. During the heating and dehydration process, a hydrolysis reaction will occur, so the product often contains CaO impurities. CaO impurities will react with SiO2 and rare earth oxides in the raw materials. Since the content of CaCl2 in the raw materials is much greater than the content of SiO2, the final product is mainly Ca2RE2O2(Si2O7) phase.

[0095] 2) When NaCl is used as the molten salt, the powder prepared is still mainly composed of rare earth oxide phase. The reason is that NaCl molten salt has a much higher melting point than the mixed molten salt of LiCl and KCl. It cannot provide a liquid phase environment for the reaction process at 900℃, which leads to the reaction not being able to occur.

[0096] 3) When K2CO3 and KCl are selected as molten salts, the powder prepared is mainly rare earth monosilicate RE2SiO5. The reason is that K2CO3 decomposes into K2O and CO2 gas at high temperature. K2O reacts with SiO2 in the raw material to form potassium silicate K2SiO3. The SiO2 content in the raw material decreases, and it tends to form rare earth monosilicate RE2SiO5. Therefore, the final product will form glass phase K2SiO3 and RE2SiO5.

[0097] 4) When NaCl and KCl are selected as molten salts, the powders prepared contain impurities such as oxygen-containing hydroxyapatite and monosilicates, and the purity of the product is not high. The reason is that although the eutectic point of the mixed molten salt of NaCl and KCl is lower than that of the single molten salt of NaCl, it can provide a certain liquid phase environment, but it is still insufficient to provide the driving force necessary for the reaction, resulting in the inability to synthesize a pure phase.

[0098] In summary, at 900℃, the CaCl2 single molten salt medium, the NaCl single molten salt medium, the mixed molten salt medium of 50% K2CO3 + 50% KCl, and the mixed molten salt medium of 50% NaCl + 50% KCl cannot provide the necessary driving force for the reaction between SiO2 and rare earth oxides. These molten salt systems either have too high a melting point to provide a sufficient liquid phase environment, or they react with the raw materials to generate impurity phases. Therefore, the LiCl + KCl mixed molten salt selected in this invention has unique advantages in the low-temperature synthesis of pure-phase high-entropy rare earth silicate ceramic powders.

[0099] Comparative Example 2:

[0100] A high-entropy rare-earth silicate ceramic powder is exactly the same as in Example 6, except that the "0.6025g of SiO2 powder" is adjusted to "0.5021g of SiO2 powder (i.e., SiO2 is not excessive)" during preparation (the high-entropy rare-earth silicate ceramic powder prepared is denoted as Sample-5).

[0101] Performance testing:

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

[0103] Depend on Figure 4 It can be seen that the high entropy rare earth silicate ceramic powder in this comparative example contains the Apatite impurity phase, and the product is impure. The reason is that the SiO2 content has a great influence on the synthesis product. Compared with the excess SiO2, the insufficient SiO2 content will cause the rare earth oxide to face the competition between RE2SiO7 and the Apatite phase, resulting in the presence of impurity phases in the reaction product.

[0104] Comparative Example 3:

[0105] A high-entropy rare-earth silicate ceramic powder is prepared in exactly the same way as in Example 6, except that "9.4524g of LiCl and 11.5517g of KCl" is replaced with "7.0014g of LiCl and 14.0027g of KCl" or "14.0027g of LiCl and 7.0014g of KCl" (the high-entropy rare-earth silicate ceramic powders prepared are referred to as Sample-6 and Sample-7 respectively).

[0106] XRD analysis revealed that the powder prepared in this comparative example was still mainly composed of rare earth oxides and SiO2, and high-entropy rare earth disilicate powder was not synthesized. This indicates that when the mass ratio of LiCl to KCl is 1:2 and 2:1 (exceeding the range of 1:1.2 to 1.4), the eutectic point cannot be reached. Therefore, 900℃ cannot provide a sufficient liquid phase environment for the reaction process, thus preventing the reaction from occurring.

[0107] Comparative Example 4:

[0108] A high-entropy rare-earth silicate ceramic powder is exactly the same as in Example 6, except that the synthesis temperature in step 2) is adjusted from "900℃" to "1000℃" during preparation (the high-entropy rare-earth silicate ceramic powder obtained is denoted as Sample-8).

[0109] Performance testing:

[0110] The SEM image of the high-entropy rare-earth silicate ceramic powder in this comparative example is shown below. Figure 5 As shown.

[0111] Depend on Figure 5 It can be seen that: compared with the high entropy rare earth silicate ceramic powder of Example 6, the high entropy rare earth silicate ceramic powder of this comparative example has significantly coarser grains, larger average particle size, and microstructure mainly consists of elongated strips and plate-like structures. The powder has poor flowability, which is not conducive to subsequent sintering, indicating that the synthesis temperature should not be too high.

[0112] 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 powder, characterized in that, Includes the following steps: 1) Add 0.1976g of Sc2O3 powder, 0.3235g of Y2O3 powder, 0.5646g of Yb2O3 powder, 0.5701g of Lu2O3 powder, 0.2927g of SiO2 powder, 8.7681g of LiCl and 10.7154g of KCl to an agate mortar and grind by hand for 30 minutes to obtain a mixed powder; 2) After pouring the mixed powder into the crucible, place it in the muffle furnace and control the heating rate to rise from room temperature to 800℃ at 8℃ / min. Then keep it at that temperature for 3 hours and cool it to room temperature with the furnace. Then ultrasonically wash it 5 times with deionized water for 60 minutes each time. Then put it in the oven and bake it at 70℃ for 6 hours to obtain high entropy rare earth silicate ceramic powder. Alternatively, it may include the following steps: 1) Add 0.3748g of Er2O3 powder, 0.3781g of Tm2O3 powder, 0.3862g of Yb2O3 powder, 0.3899g of Lu2O3 powder, 0.5652g of SiO2 powder, 9.4244g of LiCl and 11.5715g of KCl to an agate mortar and grind by hand for 30 minutes to obtain a mixed powder; 2) After pouring the mixed powder into the crucible, place it in the muffle furnace and control the heating rate to rise from room temperature to 700℃ at 8℃ / min. Then keep it at that temperature for 2 hours and cool it to room temperature with the furnace. Then ultrasonically wash it 5 times with deionized water for 60 minutes each time. Then put it in the oven and bake it at 80℃ for 6 hours to obtain high entropy rare earth silicate ceramic powder.

Images