Rapid screening method of medium-high entropy rare earth disilicate material of ytterbium disilicate

Abstract

The invention provides a rapid screening method of a medium-high-entropy rare earth disilicate material of ytterbium disilicate, which comprises the following steps: selecting a rare earth element which can form a monoclinic beta phase after a single rare earth element is equimolar doped with a Yb2Si2O7 material as a doping element to obtain the average bond length of RE-O; classifying the doping elements according to the condition that the average key length is increased or reduced, and sorting according to the doping weight; establishing a periodic table of element orthogonal incremental doping according to the sorting result, wherein the materials of the same period or group have the same incremental doping element relative to the materials of the previous period or group; carrying out material preparation and a thermal-mechanical property experiment; and summarizing experimental results into a periodic table to form a thermal-mechanical property periodic table, and selecting the most suitable material or elements needing to be doped. According to the method disclosed by the invention, the multi-component doped medium-entropy or high-entropy material can be quickly screened, and the benefits of various doped elements on certain properties brought by the medium-entropy or high-entropy material can be found out according to the thermal-mechanical property periodic table.

Description

Technical Field

[0001] The present invention relates to the field of environmental barrier ceramic materials in extremely high temperature environments, and specifically to a rapid screening method for medium- and high-entropy rare earth disilicate materials such as ytterbium disilicate, so as to intuitively display a periodic table of thermo-mechanical properties and realize rapid material screening. Background Art

[0002] With the continuous improvement of thrust-to-weight ratio of new generation aircraft engines, the internal combustion gas temperature has exceeded the tolerance limit of traditional nickel-based high-temperature alloys, and silicon carbide ceramic matrix composites (SiC CMCs) are currently the most promising high-temperature structural materials for hot end components of aircraft engines. Under the high temperature environment of the engine, the SiO2 oxide film formed on the surface of SiC CMCs will react with the water vapor produced by the combustion of aviation kerosene to generate gaseous silicon hydroxide and be carried away. Therefore, environmental barrier coatings (EBCs) are needed for surface protection.

[0003] The surface temperature of the hot end components of the new generation of high thrust-to-weight ratio air-to-ground engines will not be lower than 1500℃. The development of multifunctional integrated thermal and environmental barrier coatings (TEBCs) with excellent comprehensive performance can solve the composite needs of thermal barrier coatings and environmental barrier coatings for ceramic-based composite structural components in the extreme gas environment of aircraft, and greatly improve the thrust-to-weight ratio and long-term service stability of the engine.

[0004] In recent years, ytterbium disilicate (Yb2Si2O7) has been considered as the most promising environmental barrier coating material. However, the high thermal conductivity of Yb2Si2O7 materials needs further optimization. The concept of multi-component modification (or high entropy) brings new opportunities. For multi-component materials, when (nRE 1 / n )2Si2O7 ceramic materials are called medium-entropy or high-entropy disilicate materials when the number of rare earth cation species (n) is n=2-4 or n≥5 (for details, see the literature [L.Sun, et al. Amulticomponentγ-type(Gd 1 / 6 Tb 1 / 6 Dy 1 / 6 Tm 1 / 6 Yb 1 / 6 Lu 1 / 6)2Si2O7disilicate with outstanding thermal stability, Mater. Res. Lett. 8 (11) (2020) 424-430】). Multicomponent systems often have high mixing entropy, slow diffusion kinetics, severe lateral distortion and cocktail effect. Therefore, it has remarkable properties such as high melting point, excellent phase stability, high hardness, amorphous thermal conductivity, and excellent wear resistance and corrosion resistance (see reference [C. Oses, et al. High-entropy ceramics, Nat. Rev. Mater. 5 (4) (2020) 295-309]).

[0005] For (nRE 1 / n )2Si2O7 ceramic materials, studies have shown that when: (1) the average rare earth cation radius is less than and (2) when the average deviation is small enough, a β-type (nRE 1 / n )2Si2O7 ceramic material, and is stable in the high temperature range (see reference [Y.Luo, et al. Phase formation capability and compositional design of beta-phase multiple rare-earth principal component disilicates, Nat. Commun. 14 (1) (2023) 1275]). Previous studies have also shown that relative to Yb2Si2O7 materials, (Y 0.5 Yb 0.5 )2Si2O7 materials can reduce thermal conductivity (see reference [LRTurcer, et al. Low thermal conductivity in high-entropy rare-earth pyrosilicate solid-solutions for thermalenvironmental barrier coatings, Scr. Mater. 191 (2021) 40-45]), (Ho x Yb 1-x )2Si2O7 can affect the water vapor corrosion resistance (see reference [X.Lv, et al. Phase composition and property evolution of (Yb 1-x Ho x)2Si2O7 solid solution as environmental / thermal barrier coating candidates, J.Eur.Ceram.Soc.42(10)(2022)4377-4387】). In addition, some scholars have also studied the intermediate entropy (Sc 0.25 Y 0.25 Er 0.25 Yb 0.25 )2Si2O7 ceramic materials (see reference [X.Wang, et al. Preparation and corrosion resistance of high-entropy disilicate (Y 0.25 Yb 0.25 Er 0.25 Sc 0.25 )2Si2O7ceramics,Corros.Sci.192(2021)】) and high entropy (Sc 0.2 Y 0.2 G 0.2 Yb 0.2 Lu 0.2 )2Si2O7 ceramic materials (see reference [Y.Dong, et al.Interaction of multicomponent disilicate (Yb 0.2 Y 0.2 Lu 0.2 Sc 0.2 G 0.2 )2Si2O7 with molten calcia-magnesia-aluminosilicate, J. Adv. Ceram. 11 (1) (2021) 66-74]) were studied, and they all showed excellent calcium-magnesium-aluminum-silicon molten salt (CMAS) corrosion resistance. In addition, previous first-principles calculation studies on single rare earth element doped Yb2Si2O7 (see reference [K. Li, et al. First-principles calculations and thermal-mechanical experimental studies on middle-entropy rare-earth disilicates, Ceram. Int. 50 (13) (2024) 22290-22305]) showed that the average bond length of RE-O bond after doping is in the order of (Sc 0.5 Yb 0.5 )2Si2O7<(Yb 0.5 Lu0.5 )2Si2O7<(Y 0.5 Yb 0.5 )2Si2O7 <Yb2Si2O7<(Ho 0.5 Yb 0.5 )2Si2O7<(Tm 0.5 Yb 0.5 )2Si2O7<(Er 0.5 Yb 0.5 )2Si2O7. In summary, doping modification of Yb2Si2O7 material with other rare earth elements will change its crystal structure, and thus TEBCs material with excellent comprehensive performance can be obtained.

[0006] Since medium-entropy or high-entropy materials involve many types of rare earth elements, especially the design and experimental verification of 5 or more rare earth elements has become increasingly complicated, and the number of different medium-entropy or high-entropy combinations can even reach tens of thousands, there is an urgent need for a new method for rapid screening of medium-entropy or high-entropy materials and a theoretical basis for its optimization. Summary of the invention

[0007] The purpose of the present invention is to provide a rapid screening method for medium- and high-entropy rare earth disilicate materials of ytterbium disilicate, so as to intuitively display the periodic table of thermo-mechanical properties and realize the rapid screening of medium-entropy or high-entropy materials.

[0008] In order to achieve the above object, the present invention provides a method for rapid screening of medium-high entropy rare earth disilicate materials of ytterbium disilicate, and the specific steps are as follows:

[0009] S1: Select a rare earth element that can form a monoclinic β phase after equimolar doping of a single rare earth element in Yb2Si2O7 material as the doping element RE*, and calculate the average bond length of RE-O, where RE-O includes the bond between the Yb element and the O element and the bond between the doping element and the O element;

[0010] S2: The doping elements are divided into two categories according to whether they increase or decrease the average Yb-O bond length of the Yb2Si2O7 material, and are sorted according to the size of the doping weight;

[0011] S3: establishing a periodic table of orthogonally increasing doping of elements according to the sorting results, wherein each unit of the periodic table corresponds to a material, and materials in the same period or group have the same increasing doping element relative to materials in the previous period or group;

[0012] S4: For each material in the periodic table, perform material preparation and thermo-mechanical properties experiments to obtain experimental results;

[0013] S5: Summarize the experimental results into the periodic table to form a periodic table of thermo-mechanical properties of medium-high entropy rare earth disilicate ceramic materials, and select the most suitable material or element to be doped according to the needs.

[0014] In step S1 , the selected doping elements include at least two rare earth elements with a larger atomic radius than Yb and at least two rare earth elements with a smaller atomic radius than Yb, and the selected doping elements include Sc, Y, Ho, Er, Tm and Lu at most.

[0015] In step S1, the average bond length of RE-O is calculated, specifically comprising: using the first principle, calculating the average bond length of RE-O of the doping material obtained by equimolar doping of the doping element in the Yb2Si2O7 material; in step S2, if the average bond length of RE-O is less than the average bond length of Yb-O of the Yb2Si2O7 material, the doping element causes the average bond length of Yb-O of the Yb2Si2O7 material to decrease; otherwise, the doping element causes the average bond length of Yb-O of the Yb2Si2O7 material to increase.

[0016] Preferably, the calculation formula of the doping weight W is:

[0017]

[0018] Where W represents the doping weight, and Represent the ionic radius of the doping element RE* and the ytterbium element Yb, M RE* and M Yb represent the relative atomic masses of the doping element RE* and the ytterbium element Yb, and They respectively represent the average bond length of RE-O bonds of the material obtained by doping the doping element RE* in equal moles into the Yb2Si2O7 material and the average bond length of Yb-O of the Yb2Si2O7 material.

[0019] The step S3 specifically comprises the following steps:

[0020] S31: establishing a periodic table of m×n units, where m is one of the number of doping elements that increase the bond length and the number of doping elements that decrease the bond length, and n is the other of the number of doping elements that increase the bond length and the number of doping elements that decrease the bond length;

[0021] S32: setting the unit of the first period and the first group of the periodic table to be a Yb2Si2O7 material;

[0022] S33: In the first period of the periodic table, using one of the classified doping elements, doping the Yb2Si2O7 material in order from large to small according to the doping weight of the doping element, and the material obtained by each incremental doping occupies a unit of a group of the periodic table, so as to obtain materials corresponding to units of different groups of the first period of the periodic table;

[0023] S34: In Group I of the periodic table, using another classification of doping elements, doping is performed on the Yb2Si2O7 material in descending order according to the doping weight of the doping elements, and the material obtained by each incremental doping occupies a unit of a period of the periodic table, so as to obtain materials corresponding to units of different periods of Group I of the periodic table;

[0024] S35: Doping is performed according to the orthogonal increasing doping rule that materials of the same period of the periodic table have the same increasing doping elements relative to materials of the previous period, and materials of the same group period of the periodic table have the same increasing doping elements relative to materials of the previous group, until the m×n units of the entire periodic table are filled.

[0025] In step S4, the experimental results of the thermal-mechanical properties experiment include: experimental data of the physical properties, thermal properties, mechanical properties of the material and the thermal mismatch stress value generated when used as a coating on a SiC substrate; wherein the physical properties include at least one of density, average cation radius, relative atomic mass, and doping element type; the thermal properties include at least one of thermal expansion coefficient and thermal conductivity; and the mechanical properties include at least one of Young's modulus, microhardness, and fracture toughness.

[0026] In step S4, the material in the periodic table is a bulk ceramic material prepared by an in-situ solid phase reaction method, the molar ratio of RE to Si in the raw material of the bulk ceramic material is 1:1.1, and RE represents the Yb element, or a combination of one or more doping elements and the Yb element.

[0027] In step S4, the specific steps of preparing the material by in-situ solid phase reaction method are as follows:

[0028] S411: Using one or more rare earth oxides and silicon dioxide powder as raw powders, the molar ratio of RE:Si is 1:1.1 to determine the preparation (nRE 1 / n )2Si2O7 ceramic material required for rare earth oxide and silicon dioxide powder and weighing, wherein RE represents Yb element, or a combination of one or more doping elements and Yb element; when RE represents multiple elements, the proportion of each element is equal;

[0029] S412: Using ethanol as a medium and adding silicon nitride grinding balls into a stainless steel ball mill, the original powder, ethanol and grinding balls are mixed in a mass ratio of 1:1:1 or 1:1:2 and ball-milled for 6 to 24 hours to form a slurry. The mixed powder obtained after drying and sieving the slurry is cold isostatically pressed to obtain a blank, and then the blank is placed in a muffle furnace for pressureless sintering synthesis. The heating rate is 3 to 10°C / min, the synthesis temperature is 1500 to 1650°C, and the synthesis time is 10 to 20 hours. Finally, a ceramic block material of medium-high entropy rare earth disilicate is obtained.

[0030] The thermo-mechanical properties experiment includes:

[0031] S421: The lattice constant, density, and unit cell volume of the theoretical disilicate phase of the material are obtained through XRD patterns, and the relative atomic mass and average cation radius of the material are calculated and determined;

[0032] S422: using the Archimedean drainage method to measure the density of the prepared material, and calculating and determining the theoretical content of each phase of the material according to the proportion of the original powder used in the preparation of the material, and then calculating and determining the density and porosity of the prepared material according to the density of the theoretical disilicate phase;

[0033] S423: using a laser flash method to measure the thermal diffusivity of the prepared material using a laser thermal conductivity measuring instrument, calculating the specific heat capacity of the prepared material using the Neumann-Kopp rule, and then calculating and determining the theoretical thermal conductivity based on the thermal diffusivity, density, specific heat capacity and porosity of the prepared material;

[0034] S424: measuring the thermal expansion coefficient of the prepared material by a thermal expansion instrument using a linear expansion method;

[0035] S425: The crack length and Young's modulus of the prepared material were measured by nanoindentation using the Oliver-Pharr method;

[0036] S426: The microhardness of the prepared material is measured by a microhardness tester using an indentation method;

[0037] S427: Calculate and determine the fracture toughness of the prepared material based on the crack length and Young's modulus of the indentation;

[0038] S428: The thermal mismatch stress value generated when the prepared material is used as a SiC substrate coating is calculated based on the thermal expansion coefficient, elastic modulus and Poisson's ratio, wherein due to the presence of pores, the elastic modulus when used as a coating is 40% of the elastic modulus of the prepared material.

[0039] The step S5 also includes: summarizing the chemical properties of the materials into a periodic table.

[0040] The rapid screening method of the present invention is different from the single variable method that requires a large number of experiments. Based on previous simulation and experimental research work, a series of ytterbium disilicate and its medium and high entropy rare earth disilicate bulk ceramic materials with high density and high disilicate phase purity are designed and synthesized by in-situ solid phase reaction method according to the weight of rare earth element addition and the periodic orthogonal incremental doping law. Then, their grain size and phase high temperature stability, density, thermal conductivity, thermal expansion coefficient, microhardness, Young's modulus and fracture toughness and other thermo-mechanical properties are systematically analyzed and measured, and the corresponding thermo-mechanical properties periodic table is creatively drawn for the first time, providing theoretical support for the rapid screening and composition design of medium or high entropy TEBCs materials.

[0041] Different from the conventional single variable method that requires a large number of experiments, the rapid screening method of orthogonal incremental doping between the factors of the present invention according to the element weight can not only make full use of the correlation between the factors to quickly screen the multi-component doped medium-entropy or high-entropy materials, reducing some unnecessary workload, but also can enhance the visualization effect through the presentation of the thermo-mechanical properties periodic table, and can also find out the benefit size of certain properties of each high-entropy material according to the thermo-mechanical properties periodic table. The method of the present invention can provide theoretical support for the rapid screening and composition design of medium-entropy or high-entropy environmental barrier coating materials.

[0042] When the doping element combinations obtained by the rapid screening method of the present invention have a small number of material varieties, some of the physical properties, thermal properties, mechanical properties or chemical properties of these materials may be more extreme (extremely good or extremely poor) than those of other materials with the same number of rare earth elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart comparing a rapid screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate according to an embodiment of the present invention and a conventional screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate based on a single variable method, wherein the comparison shows the required number of selected materials.

[0044] Figure 2 is an embodiment (nRE 1 / n )2Si2O7 ceramic material as prepared XRD spectrum. In the figure, the horizontal axis is the diffraction angle 2θ, and the vertical axis is the relative intensity (arb.unit).

[0045] Figure 3 is an embodiment (nRE 1 / n )2Si2O7 ceramic material XRD spectrum after hot corrosion at 1550℃ for 100 hours. In the figure, the horizontal axis is the diffraction angle 2θ, and the vertical axis is the relative intensity (arb.unit).

[0046] Figure 4 After 100 hours of hot corrosion at 1550℃ (nRE 1 / n )Grain morphology of 2Si2O7 ceramic materials.

[0047] Figure 5 Yes(nRE 1 / n )2Si2O7 ceramic material thermal expansion coefficient versus temperature. In the figure, the horizontal axis is temperature (K) and the vertical axis is thermal expansion coefficient (10 -6 K -1 ).

[0048] Figure 6 Yes(nRE 1 / n )2Si2O7 ceramic material thermal conductivity versus temperature. In the figure, the horizontal axis is temperature (K) and the vertical axis is thermal conductivity (W·m -1 ·K -1 ).

[0049] Figure 7 Yes(nRE 1 / n )2Si2O7 ceramic material elastic modulus changes with the type of doping elements. In the figure, the horizontal axis (nRE 1 / n )2Si2O7 are different disilicate materials, and the ordinate is Young’s modulus (GPa).

[0050] Figure 8 Yes(nRE 1 / n )2Si2O7 ceramic material microhardness changes with the type of doping elements. In the figure, the horizontal axis (nRE 1 / n )2Si2O7 are different disilicate materials, and the vertical axis is microhardness (GPa).

[0051] Fig. 9 Yes(nRE 1 / n )2Si2O7 ceramic material fracture toughness changes with the type of doping elements. In the figure, the horizontal axis (nRE 1 / n )2Si2O7 is different disilicate materials, and the vertical axis is the fracture toughness (MPa·m 1 / 2 ).

[0052] Fig.10 Is drawn 4×4 (nRE 1 / n )2Si2O7 periodic table of thermo-mechanical properties of ceramic materials. DETAILED DESCRIPTION

[0053] A preferred embodiment of the present invention is given below in conjunction with the accompanying drawings and the attached tables, and is described in detail. Obviously, the accompanying drawings described below are only a preferred embodiment of the present invention, and for those skilled in the art, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0054] The rapid screening method of medium-high entropy rare earth disilicate materials of ytterbium disilicate of the present invention is mainly based on the following design ideas:

[0055] 1) From the perspective of material composition design, multiple rare earth elements are introduced into rare earth ytterbium disilicate, and the high entropy effect, that is, the high mixing entropy under high temperature conditions, can effectively reduce the Gibbs free energy of the system and obtain a stably generated single phase;

[0056] 2) From the perspective of material performance design, by selecting various specific rare earth elements, the properties of the material are compounded, and then the different sizes of various rare earth atoms are used to cause serious lattice distortion, thereby bringing physical, chemical, thermal and mechanical properties that are superior to traditional solid solutions.

[0057] 3) Considering the selection of doping elements and rapid screening methods, different from the single variable method that requires a large number of experiments, the present invention utilizes the natural law that extreme crystal structures often have extreme properties. According to literature, simulation or experience, RE1, RE2, ..., REm and REI, REII, ..., REn rare earth elements are doped in Yb2Si2O7 according to the weight of rare earth elements and the law of orthogonal incremental doping, and an m×n periodic table is obtained. The relevant physical properties and thermo-mechanical properties are measured and the thermo-mechanical performance periodic table is drawn, so that not only can the correlation between various factors be fully utilized to quickly screen multi-component doped medium-entropy or high-entropy materials, reducing some unnecessary workload, but also the visualization effect can be enhanced through the display form of the thermo-mechanical performance periodic table. In addition, according to the thermo-mechanical performance periodic table, the benefits of certain properties of each doping element after re-doping on the basis of medium-entropy or high-entropy materials can be found, and then the doping elements are re-screened and iteratively operated. These results can provide theoretical support for the rapid screening and composition design of environmental barrier coating materials.

[0058] like Figure 1 As shown, the rapid screening method of medium-high entropy rare earth disilicate materials of ytterbium disilicate of the present invention comprises the following steps:

[0059] Step S1: selecting a rare earth element that can form a monoclinic β phase after equimolar doping of a single rare earth element into a Yb2Si2O7 material as a doping element RE*, and performing a first-principles calculation to obtain an average bond length of RE-O, where RE-O includes a bond between the Yb element and the O element and a bond between the doping element and the O element;

[0060] Step S2: the doping elements are divided into two categories according to whether they cause an increase or decrease in the average bond length of Yb-O in the Yb2Si2O7 material, and are sorted according to the size of the doping weight;

[0061] In this embodiment, the number of doping elements that cause the bond length to increase is m, and the number of doping elements that cause the bond length to decrease is n. In other embodiments, the number of doping elements that cause the bond length to increase may be n, and the number of doping elements that cause the bond length to decrease may be m.

[0062] Step S3: establishing a periodic table of m×n units of orthogonally increasing doping of elements according to the sorting results, wherein each unit of the periodic table corresponds to a material, and materials in the same period of the periodic table have the same increasing doping element relative to materials in the previous period, and materials in the same group of the periodic table have the same increasing doping element relative to materials in the previous group;

[0063] Step S4: for each material in the periodic table, perform material preparation and thermo-mechanical property experiments to obtain experimental results;

[0064] Step S5: Summarize the experimental results into the periodic table to form a periodic table of thermo-mechanical properties of medium-high entropy rare earth disilicate ceramic materials, and select the most suitable material or element to be doped according to the needs.

[0065] In step S1, a rare earth element that can form a monoclinic β phase after being equimolarly doped into the Yb2Si2O7 material is selected as a doping element. Specifically, a rare earth element that can form a monoclinic β phase crystal structure when being equimolarly doped into the Yb2Si2O7 material is selected as a doping element to ensure the high-temperature stability of the phase of the doped material from room temperature to the melting point, that is, no phase change occurs.

[0066] In this embodiment, for the rare earth disilicate ceramic material with multiple rare earth components, only the average rare earth cation radius is smaller than The β phase can only be formed when the β phase is formed. Therefore, among the fourteen rare earth elements in the IIIB group of the periodic table, only seven rare earth elements, Sc, Y, Ho, Er, Tm, Yb and Lu, meet the requirements. Therefore, the selected doping elements include Sc, Y, Ho, Er, Tm and Lu. In other embodiments, the doping elements generally select no less than 2 rare earth elements with a radius greater than the atomic radius of Yb, and no less than 2 rare earth elements with a radius less than the atomic radius of Yb, and the selected doping elements include at most Sc, Y, Ho, Er, Tm and Lu.

[0067] In step S1, the average bond length of RE-O is calculated, specifically including: using the first principle, the doping material (ie (RE* 0.5 Yb 0.5 )2Si2O7 crystal structure) is used to calculate the average bond length of RE-O, where Yb is ytterbium and RE* is a selected doping element. In this embodiment, the selected doping elements include Sc, Y, Ho, Er, Tm, and Lu elements.

[0068] Among them, the average bond length of RE-O is smaller than the average bond length of Yb-O in Yb2Si2O7 material, indicating that the doping elements cause the average bond length of Yb-O in Yb2Si2O7 material to decrease; conversely, it means that the doping elements cause the average bond length of Yb-O in Yb2Si2O7 material to increase.

[0069] In the step S2, the doping elements are divided into two categories according to whether they cause an increase or decrease in the average Yb-O bond length of the Yb2Si2O7 material. The starting point is actually to use multi-component doping on a single-component material such as ytterbium disilicate. The doping elements will cause the average Yb-O bond length of the Yb2Si2O7 lattice to increase or decrease, thereby improving the ytterbium disilicate material to obtain a medium-high entropy rare earth disilicate material for modification and optimization.

[0070] In step S2, the calculation formula of the doping weight W is as follows:

[0071]

[0072] Where W represents the doping weight, and Represent the ionic radius of the doping element RE* and the ytterbium element Yb, M RE* and M Yb represent the relative atomic masses of the doping element RE* and the ytterbium element Yb, and They respectively represent the average bond length of RE-O bonds of the material obtained by doping the doping element RE* in equal moles into the Yb2Si2O7 material and the average bond length of Yb-O of the Yb2Si2O7 material.

[0073] Therefore, in the present invention, the calculation formula of the doping weight not only takes into account the atomic radius and relative atomic mass of the doping element itself, but also takes into account the influence of the Yb-O average bond length of the Yb2Si2O7 material after doping, which can better reflect the natural law of the degree of change of the crystal structure on the atomic scale by the doping element. In addition, since extreme crystal structures often bring extreme thermo-mechanical properties, the rare earth element combination materials with the best thermo-mechanical properties should often appear in the extreme element doping combination with a larger doping weight, so the order of arrangement of the periods and families of the rare earth element doping combination materials in the periodic table must be arranged from large to small according to the doping weight. In this way, it can be ensured that each rare earth doping combination has extreme properties.

[0074] Wherein, the step S3 specifically includes the following steps:

[0075] Step S31: establishing a periodic table of m×n units, where m is one of the number of doping elements that increase the bond length and the number of doping elements that decrease the bond length, and n is the other of the number of doping elements that increase the bond length and the number of doping elements that decrease the bond length;

[0076] Therefore, the periodic table of m×n units as a whole is composed of m periods 1, 2, 3, 4, ..., m horizontally and n groups I, II, III, IV, ..., n vertically, containing a total of m×n units, and therefore will include m×n types of rare earth disilicate ceramic materials.

[0077] Step S32: setting the unit of the first period and the first group of the periodic table to be Yb2Si2O7 material;

[0078] Step S33: In the first period of the periodic table, using one of the classified doping elements, doping is performed on the basis of the Yb2Si2O7 material in order from large to small according to the doping weight of the doping element, and the material obtained by each incremental doping occupies a unit of a group of the periodic table, so as to obtain materials corresponding to units of different groups of the first period of the periodic table;

[0079] That is to say, in the first period of the periodic table, the unit of the second group represents a material obtained by doping Yb2Si2O7 with RE1 in an equal molar ratio, the unit of the third group represents a material obtained by doping Yb2Si2O7 with two elements RE1 and RE2 in an equal molar ratio, and so on, until the last unit represents a material obtained by doping Yb2Si2O7 with m elements RE1, RE2, ... and REm in an equal molar ratio, wherein RE1, RE2, ... and REm represent doping elements arranged in order from large to small according to the doping weight, and they are all doping elements of the same classification.

[0080] The reason for using equimolar doping here is that, on the one hand, equimolar doping is the definition of traditional medium-entropy or high-entropy materials; on the other hand, the concentration of point defects reaches a maximum value when equimolar doping occurs, which is beneficial to the reduction of thermal conductivity. For details, please refer to the literature [C. Wan, W. Pan, Q. Xu, Y. Qin, J. Wang, Z. Qu, M. Fang, Effect of point defects on the thermal transport properties of (La x G 1-x )2Zr2O7 experiment and theoretical model, Phys.Rev.B 74 (2006) 144109】; In addition, equimolar doping also facilitates comparison of the benefits of different doping elements on thermo-mechanical properties at the same doping content.

[0081] Step S34: In Group I of the periodic table, using another classification of doping elements, doping is performed on the basis of the Yb2Si2O7 material in order from large to small according to the doping weight of the doping elements, and the material obtained by each incremental doping occupies a unit of a period of the periodic table, so as to obtain materials corresponding to units of different periods of Group I of the periodic table;

[0082] That is to say, in Group I of the periodic table, the unit of the second period represents a material obtained by doping one element REI in an equimolar ratio into Yb2Si2O7, the unit of the third period represents a material obtained by doping two elements REI and REII in an equimolar ratio into Yb2Si2O7, and so on, until the last unit represents a material obtained by doping n elements REI, REII, … and REn in an equimolar ratio into Yb2Si2O7, wherein REI, REII, … and REn represent doping elements arranged in order from large to small according to the doping weight, and are all doping elements of another classification.

[0083] Step S35: Doping is performed according to the orthogonal increasing doping rule that materials of the same period of the periodic table have the same increasing doping elements relative to materials of the previous period, and materials of the same group period of the periodic table have the same increasing doping elements relative to materials of the previous group, until the m×n units of the entire periodic table are filled.

[0084] In step S4, the experimental results of the thermo-mechanical properties experiment include: physical properties of the material (such as density, average cation radius, relative atomic mass, type of doping element, etc.), thermal properties (such as thermal expansion coefficient, thermal conductivity, etc.), mechanical properties (such as Young's modulus, microhardness, fracture toughness, etc.) and thermal mismatch stress values ​​generated when used as a coating on a SiC substrate, and other experimental data related to thermo-mechanical properties.

[0085] In step S4, the material in the periodic table (i.e., ytterbium disilicate and its high entropy rare earth disilicate) is a bulk ceramic material prepared by an in-situ solid phase reaction method, wherein the molar ratio of RE and Si in the raw material is 1:1.1, and RE represents the Yb element, or a combination of one or more doping elements and the Yb element (i.e., a combination of two or more rare earth elements of the seven rare earth elements Sc, Y, Ho, Er, Yb and Lu).

[0086] In step S4, the specific steps of preparing the material by in-situ solid phase reaction method are as follows:

[0087] Step S411: Using one or more rare earth oxides and silicon dioxide powder as raw powders, the molar ratio of RE:Si is 1:1.1 to determine the preparation (nRE 1 / n )2Si2O7 ceramic material required for rare earth oxide and silicon dioxide powder and weighing, wherein RE represents Yb element, or a combination of one or more doping elements and Yb element; when RE represents multiple elements, the proportion of each element is equal;

[0088] The initial particle size of the raw material is 1 to 5 μm, and the purity is ≥ 99.9%. In order to ensure that the disilicate block ceramic has both high density and disilicate phase purity, the molar ratio of RE:Si in the raw material is 1:1.1, wherein RE represents the Yb element, or a combination of one or more doping elements and the Yb element. When RE represents multiple elements, the proportion of each rare earth element is equal.

[0089] Step S412: using ethanol as a medium and adding silicon nitride grinding balls into a stainless steel ball mill, the original powder, ethanol and grinding balls are mixed in a mass ratio of 1:1:1 or 1:1:2 and ball-milled for 6 to 24 hours to form a slurry, the mixed powder obtained after drying and sieving the slurry is cold isostatically pressed to obtain a blank, and then the blank is placed in a muffle furnace for pressureless sintering synthesis, the heating rate is 3 to 10°C / min, the synthesis temperature is 1500 to 1650°C, and the synthesis time is 10 to 20 hours, and finally a ceramic block material of medium-high entropy rare earth disilicate is obtained.

[0090] The whole preparation process is simple and easy to prepare in large quantities.

[0091] The thermo-mechanical properties experiment of materials mainly includes 8 aspects, and the experimental steps are as follows:

[0092] Step S421: obtaining the lattice constant, density, and unit cell volume of the theoretical disilicate phase of the material through the XRD spectrum, and calculating and determining the relative atomic mass and average cation radius of the material;

[0093] Step S422: using the Archimedean drainage method to measure the density of the prepared material, and calculating the theoretical content of each phase of the material according to the proportion of the original powder used in the material preparation, and then calculating the density and porosity of the prepared material according to the density of the theoretical disilicate phase;

[0094] Step S423: using a laser flash method to measure the thermal diffusion coefficient of the prepared material using a laser thermal conductivity measuring instrument, calculating the specific heat capacity of the prepared material using the Neumann-Kopp rule, and then calculating and determining the theoretical thermal conductivity based on the thermal diffusion coefficient, density, specific heat capacity and porosity of the prepared material;

[0095] Step S424: using a thermal expansion instrument to measure the thermal expansion coefficient of the prepared material using a linear expansion method;

[0096] Step S425: using the Oliver-Pharr method to measure the crack length and Young's modulus of the prepared material by a nanoindenter;

[0097] Step S426: using an indentation method to measure the microhardness of the prepared material using a microhardness tester;

[0098] Step S427: Calculate and determine the fracture toughness of the prepared material based on the crack length and Young's modulus of the indentation;

[0099] Step S428: Calculate the thermal mismatch stress value generated when the prepared material is used as a SiC substrate coating based on the thermal expansion coefficient, elastic modulus and Poisson's ratio, wherein the elastic modulus when used as a coating is 40% of the elastic modulus of the prepared material due to the presence of pores.

[0100] Therefore, the experimental results include at least the physical properties, thermal properties and mechanical properties of the material.

[0101] The data summarized in the periodic table are not limited to the physical properties, thermal properties, and mechanical properties of the materials. Therefore, step S5 also includes: summarizing the chemical properties of the materials, such as corrosion resistance to molten salts or water vapor, into the periodic table. Thus, the thermo-mechanical properties periodic table of the present invention adds information about the material (such as physical properties, thermal properties, mechanical properties, chemical properties, etc.) at the position around each material.

[0102] In step S5, for each material in the periodic table, the experimental results of the material are filled into the unit corresponding to the material in the periodic table, thereby forming a periodic table of thermo-mechanical properties of medium-high entropy rare earth disilicate ceramic materials. Therefore, the chemical formula of ytterbium disilicate and its medium-high entropy rare earth disilicate in the periodic table is (nRE 1 / n)2Si2O7, wherein n≥1; RE represents Yb element, or a combination of one or more doping elements and Yb element (i.e. a combination of two or more rare earth elements of seven rare earth elements, Sc, Y, Ho, Er, Yb and Lu).

[0103] In step S5, the requirements correspond to information summarized in the periodic table of thermo-mechanical properties, including at least one of the physical properties, thermal properties, mechanical properties, and chemical properties of the material.

[0104] Experimental results:

[0105] In this experiment, we will draw an intuitive 4×4 periodic table of thermo-mechanical properties of ytterbium disilicate and its medium- and high-entropy rare earth disilicate materials as an example to illustrate the rapid screening method for selecting medium- and high-entropy materials with the best thermo-mechanical properties from the table. The general process is as follows: Figure 1 shown.

[0106] Among them, Figure 1 It can be seen that there are 56 material combinations of Sc, Y, Ho, Er, Tm, and Lu doped in ytterbium disilicate using the single variable method (including the ytterbium disilicate control group, the same below), while there are only 16 combinations of doping elements screened by the orthogonal incremental doping method based on weight, and the efficiency is improved by more than 70%. Therefore, the screening method of the orthogonal incremental doping method sorted by weight can greatly improve the screening of medium and high entropy materials in ytterbium disilicate.

[0107] The orthogonal incremental doping method obtained by the present invention has only 16 combinations of doping elements, and some of the physical properties, thermal properties, mechanical properties or chemical properties of these 16 materials may be more extreme (excellent or extremely poor) than the properties of other rare earth element materials with the same number. Because these 16 materials are materials with extreme crystal structures under the same number of rare earth elements screened from 56 materials, their performance is often extreme, and some performances may be extremely good, but some performances may also be extremely poor. For example, the average cation radius of the binary disilicate doped with ScYb is the smallest, and the unit cell volume is also the smallest, that is, for the binary doping of REYb, its crystal structure is extremely small, resulting in the maximum microhardness and elastic modulus, and the thermal stability should also be the best. However, ErYb is completely opposite, because under the premise of the β phase, it has the largest unit cell volume / crystal structure. Similarly, in ternary doping, the crystal structure of ScYbLu relative to other ternary dopings such as ScHoYb is also extremely small, resulting in the maximum thermal expansion coefficient. This is the main basis for the screening of the first period and the first group elements. For other combinations of unit elements in the periodic table, an opposite extreme element is doped on the extreme crystal structure, the purpose is to minimize the extremeness of the crystal structure of this material to obtain excellent comprehensive performance. For example, adding Er element to ScYb material can theoretically offset the negative impact of the extreme smallness of the crystal structure better than adding Ho or Tm elements. Here, the quantification of the extreme performance of the element is the weight formula in the present invention.

[0108] In this experiment, the specific implementation steps of the rapid screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate are as follows:

[0109] In step S1, after Yb2Si2O7 is doped with a single rare earth element in equal moles, the average radius of the rare earth element cation is smaller than In order to form the β phase (see [Y.Luo, et al. Phase formation capability and compositional design of beta-phase multiple rare-earth principal component disilicates, Nat. Commun. 14 (1) (2023) 1275] for details), therefore, the rare earth elements that need to be doped are selected, namely Sc, Y, Ho, Er, Tm and Lu. Among them, there are four rare earth elements with a radius larger than the atomic radius of Yb, namely Y, Ho, Er, and Tm; there are two rare earth elements with a radius smaller than the atomic radius of Yb, namely Sc and Lu. Then, the equimolar doped (RE 0.5 Yb 0.5The first-principles calculations of the average bond length of RE-O in the Yb2Si2O7 crystal structure were performed, where RE is Sc, Y, Ho, Er, Tm, Yb or Lu. The first-principles calculation process refers to previous work (for details, see [K. Li, et al. First-principles calculations and thermal-mechanical experimental studies on middle-entropy rare-earth disilicates, Ceram. Int. 50 (13) (2024) 22290-22305]). The calculation results of the average bond length of RE-O show that the average bond length of RE-O in the doped materials of Ho, Er and Tm elements is greater than the average bond length of Yb-O in the Yb2Si2O7 lattice, while the average bond length of RE-O in the doped materials of Sc, Y and Lu elements is less than the average bond length of Yb-O in the Yb2Si2O7 lattice.

[0110] In step S2, six rare earth elements, Sc, Y, Ho, Er, Tm and Lu, are divided into two categories according to whether they cause an increase or decrease in the average Yb-O bond length of the Yb2Si2O7 lattice and are sorted from large to small according to the doping weight.

[0111] The calculation results of the average bond length of RE-O show that the elements Ho, Er and Tm can increase the average bond length of Yb-O in the Yb2Si2O7 lattice, while the elements Sc, Y and Lu can reduce the average bond length of Yb-O in the Yb2Si2O7 lattice. At the same time, since the doping weights of Ho, Er and Tm are 3.66, 4.66 and 2.87 respectively; the doping weights of Sc, Y and Lu are 135.36, 20.19 and 31.76 respectively; the doping weights are ranked as follows: Er>Ho>Tm; Sc>Lu>Y.

[0112] In step S3, a periodic table of 4×4 units of orthogonal incremental doping of elements is established according to the sorting results. The elements RE1, RE2 and RE3 doped incrementally in different periods are selected in sequence as Er, Ho and Tm elements respectively. At the same time, the elements REI, REII and REIII doped incrementally in different groups are selected in sequence as Sc, Lu and Y elements respectively. That is, 16 kinds of disilicate materials in the periodic table are obtained, and their specific rare earth element doping combinations, codes and predicted phases are shown in Table 1.

[0113] Table 1: Doping combinations and codes of rare earth elements

[0114] S4: Prepare bulk ceramic materials of the above 16 medium-high entropy rare earth disilicates and conduct thermo-mechanical property experiments.

[0115] Among them, the specific preparation process of block ceramic materials is: according to the molar ratio of RE:Si in the raw material of 1:1.1, the mass of rare earth oxides and silicon dioxide powder required for each block ceramic material is determined and weighed. Anhydrous ethanol is used as the medium, and silicon nitride grinding balls are added to the stainless steel ball mill, so that the original powder, ethanol and grinding balls are mixed in a mass ratio of 1:1:2 and ball milled for 10 hours to form a slurry. After drying, the mixed oxide slurry is sieved with 80 mesh, and then a cold isostatic press is used to prepare block coin-shaped block blanks with a size of about Φ15mm×2mm. The briquetting process is: dry pressing 6MPa, holding for 5min; oil pressure 300MPa, holding for 30min. Finally, the blank is pressurelessly sintered in a muffle furnace. The sintering process is: heating to 1550℃ at a rate of 3℃ / min, keeping warm for 10 hours, and 16 kinds of (nRE 1 / n )2Si2O7 disilicate ceramic block. The whole preparation process is simple and easy to prepare in large quantities.

[0116] Then, the prepared (nRE 1 / n )2Si2O7 disilicate ceramic blocks are subjected to XRD phase identification to determine the physical properties of the material, such as lattice constant, theoretical density of disilicate phase, bulk ceramic density, average cation radius, relative atomic mass, type of doping elements, etc. Figure 2 Yes(nRE 1 / n )2Si2O7 ceramic material as prepared, it can be seen that the prepared disilicate block is mainly composed of a large amount of disilicate phase and a trace amount of SiO2 phase, and does not contain a monosilicate phase. Figure 2 The lattice constants and theoretical densities of different disilicate phases can be obtained by Rietveld refinement of the XRD patterns. According to the theoretical density of the disilicate phase, the density of the bulk material measured by the Archimedean method and the mass fraction of SiO2 in the raw material, the purity of the disilicate phase in the bulk material can be calculated to be about 97% and the density to be about 98%. This can meet the requirements of subsequent performance tests.

[0117] Next, the high temperature stability test of grain size and phase is carried out. Environmental barrier coatings are usually used in extreme high temperature environments, and good high temperature stability of grain size and phase is necessary. Figure 3 and Figure 4 After 100 hours of hot corrosion at 1550℃ (nRE 1 / n)XRD spectrum and grain morphology of 2Si2O7 ceramic materials. It can be seen that, except for the Z03 material, the other 15 bulk ceramics containing only β-phase disilicate and trace SiO2 still maintain a small grain size after heat treatment at 1550℃ for 100h, which is basically within 20μm, and have excellent grain size stability. The disilicate phase in the Z03 material has undergone a phase transition from β phase to γ ​​phase, and the internal grain size has been severely coarsened, resulting in a large number of cracks and holes. Therefore, the thermal stability of the Z03 material phase is poor and does not meet application requirements. However, the other 15 bulk ceramics containing only β-phase disilicate and trace SiO2 have an average rare earth cation radius value less than The disilicate phase has a stable β phase, so there is no phase change, which meets the application requirements of environmental barrier coatings in the aviation field for high-temperature stability of grain size and phase.

[0118] Then, other thermal properties (such as thermal expansion coefficient, thermal conductivity) and mechanical properties (such as Young's modulus, microhardness, fracture toughness) were measured and calculated. Figure 5-Figure 9 According to the measured thermal expansion coefficients, elastic moduli of each disilicate bulk material and SiC, and parameters such as Poisson's ratio in the literature (K. Li, et al. First-principles calculations and thermal-mechanical experimental studies on middle-entropy rare-earth disilicates, Ceram. Int. 50 (13) (2024) 22290-22305.), the thermal mismatch stress values ​​generated at 1400K when each disilicate material is used as an environmental barrier coating on a SiC substrate are calculated, thereby combining the thermal-mechanical properties of the material with the practical application of the environmental barrier coating.

[0119] S5: Summarize the above experimental results and draw a 4×4 Ytterbium disilicate and its medium-high entropy rare earth disilicate (nRE 1 / n )2Si2O7 ceramic material thermo-mechanical properties periodic table, such as Fig.10 shown.

[0120] Depend on Fig.10 It can be seen that, on the one hand, from the perspective of thermo-mechanical properties, materials with low thermal conductivity and low thermal stress are suitable for thermal environmental barrier coatings (TEBCs) (TEBCs have both thermal insulation and environmental barrier (generally refers to water vapor corrosion) functions), so Z14-(Sc 0.2 Y 0.2 Er 0.2 Yb 0.2 Lu 0.2)2Si2O7 high entropy rare earth disilicate material is the most ideal choice among these 16 extreme doping combinations. Compared with Yb2Si2O7, it not only has higher compressive stress (i.e., thermal stress is negative, which helps prevent cracks from occurring and expanding), but also has a lower overall thermal conductivity. On the other hand, from the perspective of element doping, we found that doping with Sc element tends to reduce thermal conductivity overall, and it can play a greater role when the molar ratio with Sc element exceeds 14%. Therefore, in order to obtain medium- and high-entropy rare earth disilicate materials with low thermal conductivity, a certain amount of Sc element must be doped. At the same time, it can also be seen that doping with atoms with a smaller relative atomic radius than Yb element, such as Sc element and Lu element, tends to increase thermal stress overall, while doping with Er and Ho elements with a larger relative atomic radius than Yb element tends to reduce thermal stress. Therefore, when designing the composition of medium- and high-entropy rare earth disilicate materials, it is best to dope rare earth elements with a larger and smaller relative atomic radius than Yb element. Of course, we can also analyze the effects of doping elements on fracture toughness, microhardness, etc. and design other suitable medium-entropy or high-entropy environmental barrier coating materials.

[0121] The method for rapid screening of medium-high entropy rare earth disilicate materials of ytterbium disilicate of the present invention has high purity and density of the prepared bulk ceramics, and the grain size of the bulk ceramics with a single β phase has good high temperature stability. The medium-high entropy rare earth disilicate bulk material prepared by the present invention is a material in which a plurality of rare earth elements are in-situ solid-dissolved into the lattice of ytterbium disilicate with a β phase structure. When the average rare earth cation radius value is less than Can form β phase; when the average rare earth cation radius is greater than A dual-phase ceramic material of β phase and γ phase can be formed, and the β phase will gradually transform into the γ phase at high temperature. In order to simultaneously improve the density of the block material, the purity of the disilicate phase and the high-temperature thermal stability, the raw material contains a slightly excess of SiO2. The density of the block material prepared by this method is about 98%. At the same time, the prepared disilicate ceramic block contains a trace amount of SiO2, with a mass fraction of about 3%. The prepared bulk ceramic containing only β phase disilicate and trace SiO2 has excellent grain size stability at room temperature and 1550°C. After heating at 1550°C for 100 hours, it still has a small grain size, which can meet the application requirements of environmental barrier coatings in the aviation field.

[0122] The rapid screening method of the medium-high entropy rare earth disilicate material of ytterbium disilicate of the present invention is to sort from large to small according to the weight of the added elements, and to use a periodic increasing doping method to help quickly obtain a rare earth element doping combination with the best comprehensive performance. The doping of different rare earth elements can bring about changes in thermo-mechanical properties such as density, thermal expansion coefficient, thermal conductivity, Young's modulus, microhardness, fracture toughness, etc. Moreover, extreme rare earth element doping combinations can bring about greater changes in thermo-mechanical properties. The present invention jumps out of the simple single variable method that requires a large number of experiments to find the doping method of the best element combination, but instead sorts from large to small according to the weight (extremeness) of the added elements, and uses a periodic orthogonal increasing doping method to dope other different rare earth elements on the raw materials again, which helps to quickly obtain a rare earth element doping combination with the best comprehensive performance.

[0123] The present invention can obtain an intuitive medium-high entropy rare earth disilicate thermo-mechanical property periodic table. The obtained medium-high entropy rare earth disilicate thermo-mechanical property periodic table can not only intuitively select environmental barrier coating materials that meet the requirements based on thermal and mechanical property parameters, but also reversely select new different rare earth element doping combinations for iterative operations through the laws of thermal and mechanical property changes, and at the same time, find some key elements for non-equiproportional doping component design. Provide theoretical support for the rapid screening and component design of other medium-entropy or high-entropy environmental barrier coating materials.

[0124] In summary, different from the conventional single variable method that requires a large number of experiments, the rapid screening method of orthogonal incremental doping between the factors of the present invention according to the element weight can not only make full use of the correlation between the factors to quickly screen the multi-component doped medium-entropy or high-entropy materials, reducing some unnecessary workload, but also can enhance the visualization effect through the presentation of the thermo-mechanical properties periodic table. In addition, according to the thermo-mechanical properties periodic table, the benefits of certain properties of each doping element after doping on the basis of the medium-entropy or high-entropy material can be found, and then the doping elements are screened again and iteratively operated. The present invention can provide theoretical support for the rapid screening and composition design of medium-entropy or high-entropy environmental barrier coating materials.

[0125] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A rapid screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate, It is characterized in that The specific steps are as follows: S1: Select single rare earth element equimolar doping Yb 2 Si 2 O 7 The rare earth element that can form monoclinic β phase after the material is used as the doping element RE*, and the average bond length of RE-O is calculated. RE-O includes the bond between Yb element and O element and the bond between the doping element and O element; S2: The doping elements lead to Yb 2 Si 2 O 7 The materials are divided into two categories according to whether the average Yb-O bond length increases or decreases, and are sorted by the size of the doping weight; S3: establishing a periodic table of orthogonally increasing doping of elements according to the sorting results, wherein each unit of the periodic table corresponds to a material, and materials in the same period or group have the same increasing doping element relative to materials in the previous period or group; S4: For each material in the periodic table, perform material preparation and thermo-mechanical properties experiments to obtain experimental results; S5: Summarize the experimental results into the periodic table to form a periodic table of thermo-mechanical properties of medium-high entropy rare earth disilicate ceramic materials, and select the most suitable material or element to be doped according to the needs.

2. The rapid screening method of medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 1, It is characterized in that In step S1 , the selected doping elements include at least two rare earth elements with a larger atomic radius than Yb and at least two rare earth elements with a smaller atomic radius than Yb, and the selected doping elements include Sc, Y, Ho, Er, Tm and Lu at most.

3. The rapid screening method of medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 1, It is characterized in that In step S1, the average bond length of RE-O is calculated, which specifically includes: using the first principle, the doping element is doped in equal moles in Yb 2 Si 2 O 7 The average bond length of RE-O of the doped material obtained in the material is calculated; In step S2, if the average bond length of RE-O is less than that of Yb 2 Si 2 O 7 The average bond length of Yb-O in the material, then the doping element causes Yb 2 Si 2 O 7 The average Yb-O bond length of the material is reduced; otherwise, the doping element causes the Yb 2 Si 2 O 7 The average Yb-O bond length of the material increases.

4. The rapid screening method of medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 1, It is characterized in that The calculation formula of doping weight W is: Where W represents the doping weight, and Represent the ionic radius of the doping element RE* and the ytterbium element Yb, M RE* and M Yb represent the relative atomic masses of the doping element RE* and the ytterbium element Yb, and Represents the doping elements RE* doped in Yb with equal molar ratios. 2 Si 2 O 7 The average bond length of RE-O bond and Yb 2 Si 2 O 7 The average Yb-O bond length of the material.

5. The rapid screening method of medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 1, It is characterized in that The step S3 specifically comprises the following steps: Step S31: establishing a periodic table of m×n units, where m is one of the number of doping elements that increase the bond length and the number of doping elements that decrease the bond length, and n is the other of the number of doping elements that increase the bond length and the number of doping elements that decrease the bond length; Step S32: Set the unit of the first period and the first group of the periodic table to Yb 2 Si 2 O 7 Material; Step S33: In the first period of the periodic table, using one of the doping elements, in Yb 2 Si 2 O 7 Based on the material, the doping weight of the doping element is increased in sequence from large to small, and the material obtained by each incremental doping occupies a unit of a group in the periodic table, so as to obtain the material corresponding to the unit of different groups in the first period of the periodic table; Step S34: In Group I of the periodic table, using another classification of doping elements, in Yb 2 Si 2 O 7 Based on the material, the doping weight of the doping element is incrementally doped in descending order, and the material obtained by each incremental doping occupies a unit of a period of the periodic table, so as to obtain the material corresponding to the unit of different periods of the first group of the periodic table; Step S35: Doping is performed according to the orthogonal increasing doping rule that materials of the same period of the periodic table have the same increasing doping elements relative to materials of the previous period, and materials of the same group period of the periodic table have the same increasing doping elements relative to materials of the previous group, until the m×n units of the entire periodic table are filled.

6. The rapid screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 1, It is characterized in that In step S4, the experimental results of the thermal-mechanical properties experiment include: experimental data of the physical properties, thermal properties, mechanical properties of the material and the value of thermal mismatch stress generated when used as a coating on a SiC substrate; Among them, the physical properties include at least one of density, average cation radius, relative atomic mass, and type of doping element; the thermal properties include at least one of thermal expansion coefficient and thermal conductivity; and the mechanical properties include at least one of Young's modulus, microhardness, and fracture toughness.

7. The rapid screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 1, It is characterized in that In step S4, the material in the periodic table is a bulk ceramic material prepared by an in-situ solid phase reaction method, the molar ratio of RE to Si in the raw material of the bulk ceramic material is 1:1.1, and RE represents the Yb element, or a combination of one or more doping elements and the Yb element.

8. The rapid screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 7, It is characterized in that In step S4, the specific steps of preparing the material by in-situ solid phase reaction method are as follows: Step S411: Using one or more rare earth oxides and silicon dioxide powder as raw powders, the molar ratio of RE:Si is 1:1.1 to determine the preparation (nRE 1 / n ) 2 Si 2 O 7 The mass of rare earth oxide and silicon dioxide powder required for the ceramic material is weighed, wherein RE represents the Yb element, or a combination of one or more doping elements and the Yb element; when RE represents multiple elements, the proportion of each element is equal; Step S412: using ethanol as a medium and adding silicon nitride grinding balls into a stainless steel ball mill, the original powder, ethanol and grinding balls are mixed in a mass ratio of 1:1:1 or 1:1:2 and ball-milled for 6 to 24 hours to form a slurry, the mixed powder obtained after drying and sieving the slurry is cold isostatically pressed to obtain a blank, and then the blank is placed in a muffle furnace for pressureless sintering synthesis, the heating rate is 3 to 10°C / min, the synthesis temperature is 1500 to 1650°C, and the synthesis time is 10 to 20 hours, and finally a ceramic block material of medium-high entropy rare earth disilicate is obtained.

9. The rapid screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 6, It is characterized in that The thermo-mechanical properties experiment includes: Step S421: obtaining the lattice constant, density, and unit cell volume of the theoretical disilicate phase of the material through the XRD spectrum, and calculating and determining the relative atomic mass and average cation radius of the material; Step S422: using the Archimedean drainage method to measure the density of the prepared material, and calculating the theoretical content of each phase of the material according to the proportion of the original powder used in the material preparation, and then calculating the density and porosity of the prepared material according to the density of the theoretical disilicate phase; Step S423: using a laser flash method to measure the thermal diffusion coefficient of the prepared material using a laser thermal conductivity measuring instrument, calculating the specific heat capacity of the prepared material using the Neumann-Kopp rule, and then calculating and determining the theoretical thermal conductivity based on the thermal diffusion coefficient, density, specific heat capacity and porosity of the prepared material; Step S424: using a thermal expansion instrument to measure the thermal expansion coefficient of the prepared material using a linear expansion method; Step S425: using the Oliver-Pharr method to measure the crack length and Young's modulus of the prepared material by a nanoindenter; Step S426: using an indentation method to measure the microhardness of the prepared material using a microhardness tester; Step S427: Calculate and determine the fracture toughness of the prepared material based on the crack length and Young's modulus of the indentation; Step S428: Calculate the thermal mismatch stress value generated when the prepared material is used as a SiC substrate coating based on the thermal expansion coefficient, elastic modulus and Poisson's ratio, wherein the elastic modulus when used as a coating is 40% of the elastic modulus of the prepared material due to the presence of pores.

10. The rapid screening method for medium-high entropy rare earth disilicate materials of ytterbium disilicate according to claim 1, It is characterized in that The step S5 also includes: summarizing the chemical properties of the materials into a periodic table.

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