A Component Screening Method for High-Entropy Ceramic Phase-Transformation Strengthened Silver-Based Electrical Contact Materials

Abstract

The present invention relates to the field of computational materials science and technology, and in particular to a method for screening components of a high-entropy ceramic phase-transition strengthened silver-based electrical contact material. First, based on first-principles calculations and Monte Carlo molecular dynamics simulations, combined with experimental data correction, the component ratio of (MgCoNiCuZn)O with a phase-transition temperature close to the melting point of silver and a high single-phase enthalpy value is screened out; then, the wetting behavior of liquid silver and (MgCoNiCuZn)O with different component ratios is dynamically simulated by molecular dynamics, combined with phase boundary energy calculation and wetting angle experimental verification, and the component ratio with the best wettability to liquid silver is selected; finally, samples are prepared based on spark plasma sintering, the wetting angle is measured by the sessile drop method, and the simulation parameters are feedback corrected to form a closed-loop optimization. The present invention is applicable to the collaborative optimization screening of the wettability between a high-entropy oxide system containing rare earth element doping and a liquid metal, can efficiently and accurately screen out suitable components, and improve the performance of silver-based electrical contact materials.

Description

Technical Field

[0001] The present invention relates to the technical field of computational materials science, and specifically to a method for screening components of a high-entropy ceramic phase transformation strengthened silver-based electrical contact material. Background Art

[0002] In modern electrical systems, electrical contact materials are crucial components, widely used in high- and low-voltage electrical appliances, electronic devices, power transmission and distribution, etc., undertaking the key tasks of conducting, cutting off circuits, and transmitting current. The quality of their performance directly affects the operating efficiency, reliability, and service life of electrical equipment.

[0003] Traditional silver-based electrical contact materials have been widely used for a long time due to the excellent electrical conductivity, thermal conductivity, and arc erosion resistance of silver. However, with the development of electrical equipment towards high voltage, large current, high frequency, and miniaturization, higher requirements are put forward for the performance of electrical contact materials, and some deficiencies of traditional silver-based electrical contact materials have gradually emerged.

[0004] Problems faced by traditional silver-based electrical contact materials:

[0005] Insufficient hardness and wear resistance: During frequent electrical contact processes, the friction and wear between contacts will cause the surface of the material to become rough, increasing the contact resistance, further generating excessive heat, accelerating the damage of the material, and reducing the reliability of electrical contact;

[0006] Poor anti-welding property: When short circuits or overloads occur in the circuit, the arc generated by the large current will locally melt the surface of the contacts, easily causing the contacts to weld together, making the circuit unable to be cut off normally and triggering serious safety accidents;

[0007] Limited arc erosion resistance: The high temperature and high energy of the arc will erode the surface of the electrical contact material, changing the composition and structure of the material, thus affecting the stability of its performance and service life;

[0008] Limitations of existing screening methods:

[0009] Deficiencies of single simulation methods: Some studies use single simulation methods, such as molecular dynamics simulation or first-principles calculation. Although they can predict certain properties of materials to a certain extent, due to ignoring the multi-scale characteristics of materials and the complex situations in practical applications, there are large deviations between the simulation results and the actual situations, and the component ratios screened out often cannot achieve the expected performance improvement effect in practical applications;

[0010] Disadvantages of a single experimental method: Relying solely on experiments for component screening requires a large amount of sample preparation and performance testing, which consumes a lot of time, manpower and material resources. In addition, the experimental process is affected by many factors, making it difficult to accurately control variables. The repeatability and reliability of the experimental results are poor, and it is impossible to quickly and efficiently find the optimal component ratio.

[0011] Therefore, a method for screening components of high entropy ceramic phase change strengthened silver-based electrical contact materials was proposed to address the above problems. Summary of the invention

[0012] The object of the present invention is to provide a method for screening components of high entropy ceramic phase change strengthened silver-based electrical contact materials to solve the problems raised in the above background technology.

[0013] To achieve the above object, the present invention provides the following technical solutions:

[0014] A method for screening components of high entropy ceramic phase change strengthened silver-based electrical contact materials, comprising the following steps:

[0015] S1. Preliminary screening of phase thermophysical properties: Based on first-principles calculations and Monte Carlo molecular dynamics simulations, combined with experimental data correction, the proportion of (MgCoNiCuZn)O components with a phase transition temperature close to the melting point of silver and a high single-phase enthalpy value were screened out;

[0016] S2. Further screening of interface characteristics: The wetting behavior of liquid silver and different component ratios (MgCoNiCuZn)O was simulated by molecular dynamics, and the component ratio with the best wettability with liquid silver was screened out by combining phase boundary energy calculation and wetting angle experimental verification;

[0017] S3. Collaborative optimization of experiments and simulations: Prepare samples based on spark plasma sintering, measure the wetting angle by the sessile drop method, and use feedback to correct simulation parameters to form a closed-loop optimization process.

[0018] As a preferred solution, the specific technical path of step S1 includes:

[0019] Crystal model construction and modification:

[0020] Monte Carlo method is used to randomly generate high entropy oxide crystal models with different component ratios;

[0021] Combined with the measured XRD full spectrum data, the lattice constant, atomic occupancy and defect concentration were corrected by least squares fitting to ensure that the lattice error between the model and the experimental one was less than 0.5%;

[0022] First principles calculations:

[0023] Based on density functional theory (DFT), using plane-wave pseudopotentials and the generalized gradient approximation (GGA), calculate the free energy, electronic density of states, and phonon spectra for different component ratios;

[0024] Multi-objective optimization algorithm: Optimize the component ratios through an improved genetic algorithm, and the objective function is:

[0025] , where is the component ratio vector, expressed in atomic percentage, including ; is the change in free energy of the material when the component ratio is ; is the phase transition temperature of the material when the component ratio is ; is the melting point of silver, with a value of 960 °C; is the predicted wetting angle between liquid silver and the material when the component ratio is ; is the target wetting angle to be achieved; , , are dynamic weight coefficients, determined through sensitivity analysis;

[0026] Screening criteria: Output candidate ratios with a phase transition temperature in the range of 900 °C - 1000 °C and a single-phase enthalpy value higher than 200 kJ / mol.

[0027] As a preferred solution, the specific technical path of step S2 includes:

[0028] Interface model construction:

[0029] Construct a surface model of (MgCoNiCuZn)O with a fixed bottom lattice, where the shortest side length of the surface is greater than twice the diameter of the liquid silver sphere, and perform geometric optimization to relax the atoms to the lowest energy state;

[0030] Molecular dynamics simulation:

[0031] In the Material Studio software, use the Compass force field to simulate the wetting behavior of liquid silver and high-entropy ceramics. The specific steps include:

[0032] High-temperature disordering: Heat Ag to 1200 °C in the NVT ensemble to simulate the liquid state;

[0033] Relaxation process: Perform a long relaxation of more than 100 ps at the target temperature (960 °C ± 50 °C);

[0034] Wettability quantification:

[0035] Extract through the trajectory file Droplet morphology, calculate the wetting angle ;

[0036] Calculate the interfacial energy :

[0037] where is the free energy of the composite system composed of high-entropy ceramic and liquid silver; is the free energy of the high-entropy ceramic surface model; is the free energy of liquid silver; is the interfacial area between high-entropy ceramic and liquid silver;

[0038] Adaptive correction of force field parameters:

[0039] If the deviation of the simulated elastic modulus from the experimental one adjust the force field parameters according to the following formula:

[0040] where is the corrected force field parameter; is the initial force field parameter; is the deviation value of the elastic modulus obtained from simulation from the elastic modulus measured experimentally, expressed as a percentage; is the allowable elastic modulus deviation threshold, with an initial set value of 5%.

[0041] As a preferred solution, the specific technical path of step S3 includes:

[0042] Sample preparation:

[0043] Use spark plasma sintering (SPS) technology to heat up to 1500 °C at a rate of 50 °C / min in a vacuum environment under a pressure of 50 MPa to prepare (MgCoNiCuZn)O ceramic wafers with different component ratios;

[0044] Wettability experiment:

[0045] Use the sessile drop method to measure the wetting angle of liquid silver on the surface of the ceramic wafer under argon protection, and the experimental temperature range is 900 °C - 1000 °C;

[0046] Parameter closed-loop correction:

[0047] Compare the measured wetting angle with the simulation result. If the deviation > 5%, adjust the temperature control method, step size and interfacial diffusion layer thickness in the molecular dynamics simulation.

[0048] As a preferred solution, the screening target for the component ratio of high-entropy ceramic is:

[0049] The deviation of the phase transition temperature from the melting point of silver does not exceed ±50 °C;

[0050] The wetting angle of liquid silver is less than 35°, and the phase boundary energy is lower than 0.8 J / m²;

[0051] The range of component ratios is limited to: Mg:Co:Ni:Cu:Zn = (5 - 20):(10 - 25):(15 - 30):(10 - 20):(5 - 15).

[0052] As a preferred solution, in the Monte Carlo molecular dynamics simulation, the initial ratio of virtual atoms is generated by a uniform distribution, and atom replacement is accepted or rejected through the Metropolis criterion, with an energy convergence threshold of 0.01 eV / atom.

[0053] As a preferred solution, the dynamic weight coefficients , , are adjusted according to the following rules:

[0054] When the sensitivity of the free energy change is higher than other parameters, it is increased to 0.8;

[0055] When the deviation of the phase transition temperature exceeds 30 °C, it is increased to 0.6;

[0056] When the deviation of the wetting angle exceeds 10 °, it is increased to 1.0.

[0057] As a preferred solution, the allowable elastic modulus deviation threshold is dynamically adjusted according to the complexity of the material system:

[0058] For the five - element high - entropy oxide, it is set to 5%;

[0059] For the high - entropy system with rare earth elements added, it is relaxed to 8%.

[0060] It can be seen from the technical solutions provided by the present invention above that for a method for screening components of a high - entropy ceramic phase - change - strengthened silver - based electrical contact material provided by the present invention, the beneficial effects are:

[0061] Efficient and accurate screening:

[0062] The present invention combines various advanced calculation methods such as first-principles calculation and Monte Carlo molecular dynamics simulation, which can deeply study the structure, properties and interactions of materials at the atomic scale, and accurately predict key performance parameters such as the phase transition temperature, free energy, and wettability of materials; through a multi-objective optimization algorithm, considering multiple performance indicators comprehensively and dynamically adjusting the weight coefficients, the efficiency and accuracy of screening are greatly improved, and the most potential combination can be quickly screened out from numerous possible component ratios;

[0063] A closed-loop optimization process of "calculation - experiment - correction" is formed; the simulation results provide theoretical guidance for experiments, and the experimental data in turn feedback and correct the simulation parameters, continuously optimizing the screening process to ensure that the finally screened component ratios have good performance in practical applications; this method avoids the blindness and inefficiency of traditional screening methods, saving a large amount of time and experimental costs;

[0064] Enhance electrical contact performance:

[0065] After the selected high-entropy ceramic components are combined with the silver-based material, the hardness and wear resistance of the silver-based electrical contact material can be significantly improved; the unique multi-principal element structure and high-entropy effect of the high-entropy ceramic endow it with high hardness, and the dispersion in the silver matrix can effectively resist friction and wear, reduce material loss during the electrical contact process, and extend the service life of the electrical contact material;

[0066] Optimize the anti-welding property of the material; during the electrical contact process, when current passes through the contact, an arc will be generated, which may cause the contacts to be welded together; appropriate high-entropy ceramic components can reduce the temperature distribution on the surface of the silver-based material, inhibit the generation and development of the arc, thereby reducing the occurrence of welding phenomena and improving the reliability and stability of electrical contact;

[0067] Improve the arc erosion resistance of the material; the high-entropy ceramic has good chemical stability and high-temperature performance, can remain stable under the action of arc high temperature, reduce the degree of arc erosion of the silver-based material, and ensure the stability of the performance of the electrical contact material during long-term use;

[0068] Improve electrical conductivity: Although the high-entropy ceramic itself has relatively poor electrical conductivity, by precisely screening the component ratios, the high-entropy ceramic can exist in a suitable form and distribution in the silver-based material, minimizing the impact on electrical conductivity while enhancing other properties; moreover, the good interfacial bonding between the high-entropy ceramic and the silver-based material is conducive to electron transport, and may even improve the electrical conductivity uniformity of the material to a certain extent and enhance the overall electrical conductivity. Brief Description of the Drawings

[0069] Figure 1 It is a schematic flow chart of the steps of a method for screening components of a high-entropy ceramic phase change strengthened silver-based electrical contact material of the present invention. Detailed implementation mode

[0070] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0071] To better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the specification drawings and specific implementation modes.

[0072] As Figure 1 shown, an embodiment of the present invention provides a method for screening components of a high-entropy ceramic phase-change strengthened silver-based electrical contact material, including the following steps:

[0073] S1. Preliminary screening of phase thermophysical properties: Based on first-principles calculations and Monte Carlo molecular dynamics simulations, combined with experimental data correction, screen out the component ratio of (MgCoNiCuZn)O with a phase change temperature close to the melting point of silver and a high single-phase enthalpy value;

[0074] S2. Further screening of interface characteristics: By molecular dynamics dynamic simulation of the wetting behavior of liquid silver and (MgCoNiCuZn)O with different component ratios, combined with phase boundary energy calculation and wetting angle experimental verification, screen out the component ratio with the best wettability with liquid silver;

[0075] S3. Experimental and simulation collaborative optimization: Based on the preparation of samples by spark plasma sintering, measure the wetting angle by the sessile drop method, and feedback and correct the simulation parameters to form a closed-loop optimization process.

[0076] In this embodiment, step S1 aims to preliminarily screen out the component ratio with a phase change temperature close to the melting point of silver and a high single-phase enthalpy value from among numerous possible component ratios of (MgCoNiCuZn)O through theoretical calculations and simulations, combined with experimental data correction; this helps to narrow the scope of subsequent screening, improve the screening efficiency, and lay a foundation for obtaining a high-entropy ceramic phase-change strengthened silver-based electrical contact material with excellent performance;

[0077] As the starting step of the entire component screening method, it provides potential candidate component ratios for subsequent interface characteristic screening and experimental and simulation collaborative optimization; by initially controlling the phase thermophysical properties, it ensures that the components studied subsequently match the application requirements of silver-based electrical contact materials in terms of thermodynamics and phase change characteristics;

[0078] Step S1 adopts a method that combines first-principles calculations with Monte Carlo molecular dynamics simulations and is corrected by combining experimental data. The comprehensive application of such multi-scale and multi-methods can more accurately predict the phase thermophysical properties of materials and improve the accuracy of screening. At the same time, a multi-objective optimization algorithm is introduced, considering multiple factors such as free energy, phase transition temperature, and predicted wetting angle, dynamically adjusting the weight coefficients, and realizing a more scientific and efficient screening of component ratios;

[0079] The detailed steps of step S1 include:

[0080] S1-1: Crystal model construction and correction:

[0081] S1-1-1: Model generation: Use the Monte Carlo method to randomly generate high-entropy oxide crystal models with different component ratios; the Monte Carlo method is based on the principle of probability and statistics, and can explore the crystal structure possibilities under different component ratios in a large number of random attempts, providing diverse initial models for subsequent accurate calculations;

[0082] S1-1-2: Model correction: Combine the measured XRD full-spectrum data and correct the lattice constant, atomic occupancy, and defect concentration by least-squares fitting; the least-squares method is a mathematical optimization technique that finds the best function match for data by minimizing the sum of the squares of errors; in this way, ensure that the model lattice error from the experiment is less than 0.5%, making the constructed crystal model closer to the structure of the actual material;

[0083] S1-2: First-principles calculation: Based on density functional theory (DFT), use plane-wave pseudopotentials and the generalized gradient approximation (GGA) to calculate the free energy, electronic density of states, and phonon spectrum of different component ratios; density functional theory is a quantum mechanics method for studying the electronic structure of many-electron systems, and plane-wave pseudopotentials and the generalized gradient approximation are its commonly used implementation methods; through these calculations, the thermodynamic properties and electronic structure of materials under different component ratios can be deeply understood, providing a theoretical basis for subsequent optimization;

[0084] S1-3: Multi-objective optimization algorithm:

[0085] S1-3-1: Objective function setting: Optimize the component ratio through an improved genetic algorithm, and the objective function is:

[0086] , where, is the component ratio vector, expressed in atomic percentages, (such as ); is the change in free energy of the material when the component ratio is ; is the phase transition temperature of the material when the component ratio is ; is the melting point of silver, with a value of 960 °C; is the component ratio of is the predicted wetting angle between liquid silver and the material when is the target wetting angle to be achieved; , , are dynamic weight coefficients, determined through sensitivity analysis; this objective function comprehensively considers three key factors: free energy, phase change temperature, and predicted wetting angle, to achieve multi-objective optimization of the component ratio;

[0087] S1-3-2: Dynamic weight adjustment: Dynamically adjust the weight coefficients according to the sensitivity and deviation of different parameters , , ; when the sensitivity of the free energy change amount is higher than other parameters (i.e., phase change temperature deviation and wetting angle deviation), is increased to 0.8; when the phase change temperature deviation exceeds 30 °C, is increased to 0.6; when the wetting angle deviation exceeds 10°, is increased to 1.0; this dynamic adjustment mechanism can highlight key factors according to the actual situation, improving the pertinence and accuracy of optimization;

[0088] S1-4: Determination of screening criteria: Output the candidate ratio with a phase change temperature in the range of 900 °C - 1000 °C and a single-phase enthalpy value higher than 200 kJ / mol; this screening criterion ensures that the initially screened component ratio is close to the melting point of silver in terms of phase change temperature and has a high single-phase enthalpy value, which is beneficial to forming a good composite system with silver-based materials in the subsequent process and improving the performance of the electrical contact material.

[0089] Furthermore, in step S2, through molecular dynamics simulation and phase boundary energy calculation, combined with wetting angle experimental verification, the interfacial interaction between liquid silver and different component ratios (MgCoNiCuZn)O is deeply explored, and the component ratio with the best wettability with liquid silver is accurately screened out; good wettability helps to improve the bonding strength and interfacial stability between the high-entropy ceramic and the silver-based material, thereby enhancing the overall performance of the silver-based electrical contact material, such as electrical conductivity, arc erosion resistance, etc.;

[0090] Based on the component ratio with appropriate thermophysical properties initially screened out in step S1, step S2 focuses on the interfacial characteristics of the material; the interfacial performance plays a key role in the performance of the composite material. By screening out the component ratio with the best wettability, it provides an important guarantee for the subsequent preparation of high-performance high-entropy ceramic phase transformation strengthened silver-based electrical contact materials, and further optimizes the microstructure and performance of the material.

[0091] Using molecular dynamics dynamic simulation technology, the wetting behavior of liquid silver and high-entropy ceramics can be observed in real time at the atomic scale. Combining the accurate calculation and experimental verification of the phase boundary energy, a complete set of interface performance evaluation methods has been formed. At the same time, a force field parameter adaptive correction algorithm is introduced to adjust the force field parameters in real time according to the deviation between the simulated and experimental elastic moduli, effectively improving the accuracy of the simulation and making the screening results more in line with the actual situation.

[0092] The detailed steps of step S2 include:

[0093] S2-1: Interface model construction:

[0094] S2-1-1: Model design: Construct a (MgCoNiCuZn)O surface model with a fixed bottom lattice, and the shortest side length of the surface is greater than 2 times the diameter of the liquid silver sphere (≥20 nm); such a design is to ensure that there is enough interaction space between the liquid silver sphere and the high-entropy ceramic surface during the simulation, avoiding the influence of boundary effects and making the simulation results better reflect the real interface situation.

[0095] S2-1-2: Geometric optimization: Perform geometric optimization on the constructed surface model to relax the atoms to the lowest energy state; during this process, the atoms will adjust their positions according to the forces between each other and finally reach a relatively stable energy state, obtaining a more realistic interface model structure.

[0096] S2-2: Molecular dynamics simulation:

[0097] S2-2-1: High-temperature disordering: In the MaterialStudio software, use the Compass force field to simulate the wetting behavior of liquid silver and high-entropy ceramics; first, heat Ag to 1200 °C in the NVT ensemble (constant number of particles, constant volume, constant temperature) to simulate the liquid state; at high temperatures, the movement of silver atoms becomes more disordered, thus showing the characteristics of the liquid state, providing a basis for subsequent simulation of the interaction between liquid silver and high-entropy ceramics.

[0098] S2-2-2: Relaxation process: Adjust the temperature to the target temperature (960 °C ± 50 °C) and perform a long relaxation of more than 100 ps; during this process, the system will gradually reach an equilibrium state, making the simulation results better reflect the real thermodynamic and kinetic properties; a long relaxation can ensure the stability of the movement and distribution of atoms, thus more accurately simulating the wetting behavior of liquid silver on the high-entropy ceramic surface.

[0099] S2-3: Wettability quantification:

[0100] S2-3-1: Contact angle calculation: Extract the Ag droplet morphology from the trajectory file and calculate the contact angle ; The wetting angle is an important indicator to measure wettability, which reflects the spreading degree of liquid silver on the high-entropy ceramic surface. By analyzing the atomic trajectories recorded during the simulation, the shape and contact angle of the droplet can be determined, and thus the value of the wetting angle can be obtained.

[0101] S2-3-2: Interfacial energy calculation: Calculate the interfacial energy , and the formula is:

[0102] , where is the free energy of the composite system composed of high-entropy ceramic and liquid silver; is the free energy of the high-entropy ceramic surface model; is the free energy of liquid silver; is the interfacial area between high-entropy ceramic and liquid silver. The interfacial energy reflects the stability of the interface. A lower interfacial energy indicates a closer interface combination, which is beneficial to improving the performance of the material.

[0103] S2-4: Adaptive correction of force field parameters:

[0104] S2-4-1: Deviation judgment: Compare the elastic modulus obtained from the simulation with the experimentally measured elastic modulus and calculate the deviation , if , it indicates that there is a large difference between the simulation result and the experimental result, and the force field parameters need to be corrected;

[0105] S2-4-2: Parameter adjustment: Adjust the force field parameters according to the following formula:

[0106] , where is the corrected force field parameter; is the initial force field parameter; is the deviation value of the elastic modulus obtained from the simulation and the experimentally measured elastic modulus, expressed as a percentage; is the allowable elastic modulus deviation threshold, and the initial set value is 5%. Through this adaptive correction mechanism, the simulation result can be closer to the experimental value, improving the accuracy and reliability of the simulation. The corrected force field parameters can be used for molecular dynamics simulation again to further optimize the screening results.

[0107] Further, in step S3, a closed-loop optimization process is formed by combining simulation with experiments. On the one hand, actual samples are prepared by spark plasma sintering, and accurate wetting angle experimental data are obtained through the sessile drop method. On the other hand, the experimental data are fed back to the simulation process to correct the simulation parameters, thereby improving the accuracy and reliability of the simulation. Ultimately, the component ratio of high-entropy ceramics with better comprehensive performance can be screened out, providing a solid guarantee for the preparation of high-performance high-entropy ceramic phase transformation strengthened silver-based electrical contact materials. Based on the preliminary screening of the appropriate component ratio of phase thermophysical properties in step S1 and the further screening of the component ratio with better wettability in step S2, step S3 plays a key role in verification and optimization. The experimental data can verify the accuracy of the simulation results and at the same time correct the simulation parameters, enabling subsequent simulations to more accurately predict the material properties, providing an important basis for determining the optimal component ratio ultimately, and ensuring the scientificity and effectiveness of the entire screening method.

[0108] Step S3 constructs a closed-loop optimization system of "calculation-experiment-correction", breaking through the limitations of traditional single simulation or experimental screening methods. Through real-time feedback and adjustment, the synergistic effect of simulation and experiment is realized, greatly improving the screening efficiency and accuracy. At the same time, this closed-loop optimization process has good generality and scalability, and is applicable to the material screening and performance optimization of different systems.

[0109] The specific operation steps of step S3 are as follows:

[0110] S3-1: Sample preparation:

[0111] S3-1-1: Raw material preparation: According to the different component ratios screened out in steps S1 and S2, prepare the corresponding (MgCoNiCuZn)O raw material powders. Ensure that the purity and particle size of the raw materials meet the requirements of spark plasma sintering to ensure the uniform quality of the prepared ceramic sheets.

[0112] S3-1-2: Molding: Load the prepared raw material powders into a specific mold, and the mold should be selected according to the size and shape of the required ceramic sheet. During the molding process, pay attention to the uniform distribution of the powders to avoid local density differences.

[0113] S3-1-3: Spark plasma sintering (SPS): Adopt the spark plasma sintering technology to carry out sintering in a vacuum environment. Raise the temperature to 1500°C at a heating rate of 50°C / min, and at the same time apply a pressure of 50 MPa. During the sintering process, the high temperature and high pressure generated by the spark plasma can promote the rapid sintering and densification of the powder particles, thereby preparing (MgCoNiCuZn)O ceramic sheets with good performance. After sintering, cool to room temperature with the furnace and take out the ceramic sheets for standby.

[0114] S3-2: Wettability experiment:

[0115] S3-2-1: Sample Pretreatment: Perform surface treatment on the prepared ceramic chips, such as grinding, polishing, etc., to obtain a flat and clean surface, ensuring the accuracy of experimental results; meanwhile, process the silver block into appropriate dimensions as the source of liquid silver.

[0116] S3-2-2: Sessile Drop Method Experiment: Use the sessile drop method to measure the wetting angle of liquid silver on the surface of the ceramic chip under argon protection; place the ceramic chip in a high-temperature furnace, heat it to the experimental temperature range (900°C - 1000°C), then place the silver block on the surface of the ceramic chip to make it melt and form a liquid silver drop; record the spreading process of the liquid silver drop on the surface of the ceramic chip through equipment such as a high-speed camera until it reaches an equilibrium state; finally, use image processing software to analyze the captured images and calculate the actual wetting angle of liquid silver on the surface of the ceramic chip.

[0117] S3-3: Parameter Closed-Loop Correction:

[0118] S3-3-1: Result Comparison: Compare the wetting angle measured by the sessile drop method with the predicted wetting angle obtained from molecular dynamics simulation, and calculate the deviation between the two; if the deviation exceeds 5%, it indicates that there is a large difference between the simulation result and the actual situation, and the simulation parameters need to be adjusted.

[0119] S3-3-2: Parameter Adjustment: Adjust the relevant parameters in the molecular dynamics simulation according to the deviation situation; specifically include: change the temperature control method from Berendsen to Nose-Hoover. The Nose-Hoover temperature control method can more accurately simulate the temperature fluctuations of the system and improve the accuracy of temperature control; adjust the time step from 1 fs to 0.5 fs. Reducing the time step can improve the simulation accuracy but will increase the calculation time; increase the thickness of the interfacial diffusion layer to 2 nm to more accurately simulate the interfacial diffusion behavior between liquid silver and high-entropy ceramics.

[0120] S3-3-3: Re-Simulation and Verification: Use the adjusted simulation parameters to perform molecular dynamics simulation again and compare the new simulation results with the experimental data; if the deviation is still large, repeat the above parameter adjustment process until the deviation between the simulation result and the experimental data is within an acceptable range; through this closed-loop correction mechanism, continuously optimize the simulation parameters, improve the accuracy and reliability of the simulation, and thus screen out the high-entropy ceramic component ratio that better meets the actual requirements.

[0121] In this embodiment, in the Monte Carlo molecular dynamics simulation, the initial ratio of virtual atoms is generated by a uniform distribution, and atom replacement is accepted or rejected through the Metropolis criterion, and the energy convergence threshold is 0.01 eV / atom.

[0122] The present invention will be further described below in conjunction with specific embodiments:

[0123] I. Experimental materials and equipment:

[0124] Materials:

[0125] Magnesium oxide (MgO), cobalt oxide (CoO), nickel oxide (NiO), copper oxide (CuO), and zinc oxide (ZnO) powders with a purity of not less than 99.9% are used to prepare (MgCoNiCuZn)O high-entropy ceramics;

[0126] A silver block with a purity of 99.99% is used for the wettability experiment;

[0127] Equipment:

[0128] Planetary ball mill: used for mixing and refining raw material powders;

[0129] Spark plasma sintering furnace (SPS): used to prepare (MgCoNiCuZn)O ceramic sheets;

[0130] High-temperature furnace: equipped with an argon protection device, used for the sessile drop method wettability experiment;

[0131] Scanning electron microscope (SEM): used to observe the microstructure of samples;

[0132] X-ray diffractometer (XRD): used to analyze the crystal structure of samples;

[0133] Molecular dynamics simulation software: MaterialStudio;

[0134] II. Implementation steps:

[0135] Step S1: Preliminary screening of phase thermophysical properties:

[0136] S1-1: Crystal model construction and correction:

[0137] Model generation: Using the Monte Carlo method, 100 different component ratio (MgCoNiCuZn)O high-entropy oxide crystal models are randomly generated on a computer; the component ratio range is set as Mg:Co:Ni:Cu:Zn = (5 - 20):(10 - 25):(15 - 30):(10 - 20):(5 - 15) (atomic percentage);

[0138] Model correction: Weigh the above 100 kinds of raw material powders according to the corresponding proportions, and ball-mill them in a planetary ball mill at a speed of 300 r / min for 12 h to make the powders fully and evenly mixed; then perform XRD tests to obtain the measured full-spectrum XRD data; use the least-squares method to fit and correct the lattice constants, atomic occupancies, and defect concentrations of the crystal model to ensure that the lattice error between the model and the experiment is less than 0.5%;

[0139] S1-2: First-principles calculation:

[0140] Based on the density functional theory (DFT), using plane-wave pseudopotentials and the generalized gradient approximation (GGA), use the corresponding calculation software to calculate the corrected 100 crystal models to obtain the free energies, electronic density of states, and phonon spectra of different component ratios; during the calculation process, the plane-wave cutoff energy is set to 500 eV, and the k-point mesh of the Brillouin zone is set to 4×4×4;

[0141] S1-3: Multi-objective optimization algorithm:

[0142] Objective function setting: Optimize the component ratios through an improved genetic algorithm, and the objective function is:

[0143] , where, is the component ratio vector, expressed in atomic percentage, (such as ); is the change in free energy of the material when the component ratio is ; is the phase transition temperature of the material when the component ratio is ; is the melting point of silver, with a value of 960 °C; is the predicted wetting angle between liquid silver and the material when the component ratio is ; is the target wetting angle to be achieved; , , are the dynamic weight coefficients, with initial values set to 0.3, 0.3, and 0.4 respectively;

[0144] Dynamic weight adjustment: During the optimization process, monitor the sensitivity and deviation of each parameter in real time; when the sensitivity of the change in free energy is higher than other parameters (i.e., the phase transition temperature deviation and the wetting angle deviation), is increased to 0.8; when the phase transition temperature deviation exceeds 30 °C, is increased to 0.6; when the wetting angle deviation exceeds 10 °, is increased to 1.0;

[0145] Optimized calculation: After 50 generations of iterative calculations using the genetic algorithm, the component ratios that optimize the objective function are screened out.

[0146] S1-4: Determination of screening criteria:

[0147] From the above optimization results, 10 candidate component ratios are output where the phase transition temperature is in the range of 900°C - 1000°C and the single-phase enthalpy value is higher than 200 kJ / mol.

[0148] Step S2: Further screening of interface characteristics:

[0149] S2-1: Construction of interface model:

[0150] Model design: For the above 10 candidate component ratios, a surface model of (MgCoNiCuZn)O with a fixed bottom lattice is constructed, and the shortest side length of the surface is set to 25 nm.

[0151] Geometric optimization: Using the geometric optimization module in MaterialStudio software, the surface model is optimized to relax the atoms to the lowest energy state; during the optimization process, the Smart algorithm is adopted and the convergence accuracy is set to Fine.

[0152] S2-2: Molecular dynamics simulation:

[0153] High-temperature disordering: In the MaterialStudio software, using the Compass force field, Ag atoms are heated to 1200°C in the NVT ensemble to simulate liquid silver; during the heating process, the heating rate is set to 10 K / ps and the duration is 50 ps.

[0154] Relaxation process: The temperature is adjusted to 960°C and a long relaxation of 150 ps is carried out to bring the system to an equilibrium state; during the relaxation process, the time step is set to 1 fs.

[0155] S2-3: Quantification of wettability:

[0156] Calculation of wetting angle: Through the trajectory file obtained from the simulation, the Ag droplet morphology is extracted using the analysis tool in the software to calculate the wetting angle ;

[0157] Calculation of phase boundary energy: Calculate the phase boundary energy , the formula is:

[0158] , where is the free energy of the composite system composed of high-entropy ceramic and liquid silver; is the free energy of the high-entropy ceramic surface model; is the free energy of liquid silver; is the interfacial area between the high-entropy ceramic and liquid silver;

[0159] S2-4: Adaptive correction of force field parameters:

[0160] Deviation judgment: Compare the elastic modulus obtained from the simulation with the experimental elastic modulus of a similar system in the relevant literature, and calculate the deviation , if , then perform force field parameter correction;

[0161] Parameter adjustment: Adjust the force field parameters according to the following formula:

[0162] , where is the corrected force field parameter; is the initial force field parameter; is the deviation value of the elastic modulus obtained from the simulation and the experimentally measured elastic modulus, expressed as a percentage; is the allowable deviation threshold of the elastic modulus, with an initial setting value of 5%. Perform molecular dynamics simulation again using the corrected force field parameters until the deviation between the simulation and the experimental elastic modulus is within 5%; Finally, screen out the 3 component ratios with the best wettability with liquid silver;

[0163] Step S3: Experimental and simulation collaborative optimization:

[0164] S3-1: Sample preparation:

[0165] Raw material preparation: Accurately weigh the corresponding MgO, CoO, NiO, CuO, and ZnO powders according to the 3 component ratios screened out;

[0166] Molding: Load the weighed powders into a graphite mold, and the powder filling should be uniform;

[0167] Spark plasma sintering (SPS): In a vacuum environment, raise the temperature to 1500 °C at a heating rate of 50 °C / min, while applying a pressure of 50 MPa, keep the temperature and pressure for 10 min, and then cool to room temperature with the furnace to prepare (MgCoNiCuZn)O ceramic sheets with 3 different component ratios;

[0168] S3-2: Wettability experiment:

[0169] Sample pretreatment: Grind and polish the prepared ceramic sheets to make their surface roughness reach Ra ≤ 0.1 μm;

[0170] Sessile drop method experiment: Place the ceramic piece in a high-temperature furnace, introduce argon for protection, and raise the temperature to 950°C at a heating rate of 20°C / min; place the silver block on the surface of the ceramic piece to melt it into a liquid silver drop; use a high-speed camera to record the spreading process of the liquid silver drop on the surface of the ceramic piece for a duration of 10 min; use image processing software to analyze the captured images and calculate the actual wetting angle of the liquid silver on the surface of the ceramic piece.

[0171] S3-3: Parameter closed-loop correction:

[0172] Result comparison: Compare the wetting angle measured by the sessile drop method with the predicted wetting angle obtained from molecular dynamics simulation, and calculate the deviation between the two; if the deviation exceeds 5%, parameter adjustment is carried out.

[0173] Parameter adjustment: Change the temperature control method in the molecular dynamics simulation from Berendsen to Nose-Hoover, adjust the time step from 1 fs to 0.5 fs, and increase the thickness of the interfacial diffusion layer to 2 nm.

[0174] Re-simulation and verification: Conduct molecular dynamics simulation again using the adjusted simulation parameters, and compare the new simulation results with the experimental data; if the deviation is still large, repeat the above parameter adjustment process until the deviation between the simulation results and the experimental data is within 5%; finally, determine the optimal proportion of the high-entropy ceramic component.

[0175] III. Result analysis:

[0176] Microstructure analysis:

[0177] Use a scanning electron microscope (SEM) to observe the microstructure of the high-entropy ceramic phase transformation strengthened silver-based electrical contact material sample finally selected, and analyze the interfacial bonding situation and distribution state between the high-entropy ceramic and the silver-based.

[0178] Performance test:

[0179] Conduct performance tests such as conductivity, hardness, and arc erosion resistance on the sample to evaluate the actual application performance of the material; the results show that the material obtained by the component screening method of the present invention has significant improvements in various performance indicators and meets the usage requirements of the high-entropy ceramic phase transformation strengthened silver-based electrical contact material.

[0180] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for screening components of a high-entropy ceramic phase transformation strengthened silver-based electrical contact material, characterized in that: It includes the following steps: S1. Preliminary screening of thermophysical properties: Based on first-principles calculations and Monte Carlo molecular dynamics simulations, combined with experimental data correction, the component ratio of (MgCoNiCuZn)O with a phase transition temperature close to the melting point of silver and a high single-phase enthalpy value is screened. The specific technical path of step S1 includes: Crystal model construction and correction: Using the Monte Carlo method to randomly generate high-entropy oxide crystal models with different component ratios; Combined with the measured XRD full-spectrum data, the lattice constant, atomic occupancy, and defect concentration are corrected by least-squares fitting to ensure that the lattice error between the model and the experiment is less than 0.5%; First-principles calculation: Based on the density functional theory DFT, using plane-wave pseudopotentials and the generalized gradient approximation GGA, calculate the free energy, electronic density of states, and phonon spectrum of different component ratios; Multi-objective optimization algorithm: Optimize the component ratio through an improved genetic algorithm, and the objective function is: , where is the component ratio vector, expressed in atomic percentage, including ; is the free energy change of the material when the component ratio is ; is the phase transition temperature of the material when the component ratio is ; is the melting point of silver, with a value of 960 °C; is the predicted wetting angle between liquid silver and the material when the component ratio is ; is the target wetting angle to be achieved; , , are the dynamic weight coefficients, determined by sensitivity analysis; Screening criteria: Output candidate ratios with a phase transition temperature in the range of 900°C - 1000°C and a single-phase enthalpy value higher than 200 kJ / mol; S2. Further screening of interface characteristics: By molecular dynamics dynamic simulation of the wetting behavior of liquid silver and (MgCoNiCuZn)O with different component ratios, combined with phase boundary energy calculation and wetting angle experimental verification, screen out the component ratio with the best wettability with liquid silver; S3. Experimental and simulation collaborative optimization: Based on spark plasma sintering to prepare samples, measure the wetting angle by the sessile drop method, and feedback to correct the simulation parameters to form a closed-loop optimization process.

2. A method for screening components of a high-entropy ceramic phase-transition strengthened silver-based electrical contact material according to claim 1, characterized in that: The specific technical path of step S2 includes: Interface model construction: Construct a (MgCoNiCuZn)O surface model with a fixed bottom lattice, where the shortest side length of the surface is greater than 2 times the diameter of the liquid silver sphere, and geometric optimization is performed to relax the atoms to the lowest energy state; Molecular dynamics simulation: In the Material Studio software, use the Compass force field to simulate the wetting behavior of liquid silver and high-entropy ceramics. The specific steps include: High-temperature disordering: Heat Ag to 1200°C in the NVT ensemble to simulate the liquid state; Relaxation process: Perform a long-time relaxation of more than 100 ps at the target temperature of 960°C ± 50°C; Wettability quantification: Extraction through trajectory file Droplet morphology, calculate wetting angle ; Calculating the phase boundary energy : , where is the free energy of the composite system composed of high-entropy ceramics and liquid silver; is the free energy of the high-entropy ceramic surface model; is the free energy of liquid silver; is the interfacial area between high-entropy ceramics and liquid silver; Adaptive correction of force field parameters: If the deviation of the simulated elastic modulus from the experimental value , adjust the force field parameters according to the following formula: , where is the corrected force field parameter; is the initial force field parameter; is the allowable deviation threshold of the elastic modulus, and the initial set value is 5%.

3. A method for screening components of a high-entropy ceramic phase transformation strengthened silver-based electrical contact material according to claim 2, characterized in that: The specific technical path of step S3 includes: Sample preparation: Using the spark plasma sintering SPS technology, heat up to 1500°C at a rate of 50°C / min in a vacuum environment, with a pressure of 50 MPa, to prepare (MgCoNiCuZn)O ceramic sheets with different component ratios; Wettability experiment: Use the sessile drop method to measure the wetting angle of liquid silver on the surface of the ceramic sheet under argon protection, and the experimental temperature range is 900°C - 1000°C; Parameter closed-loop correction: Compare the measured wetting angle with the simulation results. If the deviation > 5%, adjust the temperature control method, step size, and interface diffusion layer thickness in the molecular dynamics simulation.

4. A method for screening components of a high-entropy ceramic phase-transition strengthened silver-based electrical contact material according to claim 3, characterized in that: The screening target for the component ratio of the high-entropy ceramic is: The deviation of the phase transition temperature from the melting point of silver does not exceed ±50°C; The wetting angle of liquid silver is less than 35°, and the phase boundary energy is lower than 0.8 J / m²; The component ratio range is limited to: Mg:Co:Ni:Cu:Zn = (5 - 20):(10 - 25):(15 - 30):(10 - 20):(5 - 15).

5. A method for screening components of a high-entropy ceramic phase-transition strengthened silver-based electrical contact material according to claim 4, characterized in that: In the Monte Carlo molecular dynamics simulation, the initial ratio of virtual atoms is generated by uniform distribution, and atom replacement is accepted or rejected through the Metropolis criterion. The energy convergence threshold is 0.01 eV / atom.

6. A method for screening components of a high-entropy ceramic phase-transition strengthened silver-based electrical contact material according to claim 5, characterized in that: The dynamic weight coefficient , , has the following adjustment rules: When the free energy change has a higher sensitivity than other parameters, increase it to 0.8; When the phase change temperature deviation exceeds 30 °C, it is increased to 0.6; When the wetting angle deviation exceeds 10°, Increase to 1.

0.

7. A method for screening components of a high-entropy ceramic phase transformation strengthened silver-based electrical contact material according to claim 6, characterized in that: The allowable elastic modulus deviation threshold Dynamically adjusted according to the complexity of the material system: For the quinary high-entropy oxide, Set to 5%; For the high-entropy system with the addition of rare-earth elements, It is relaxed to 8%.

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