High-entropy ceramic phase change reinforced silver-based electric contact material component screening method

Abstract

The invention relates to the technical field of computational material science, in particular to a high-entropy ceramic phase change strengthened silver-based electric contact material component screening method, which comprises the following steps of: firstly, based on first principle calculation and Monte Carlo molecular dynamics simulation, combining experimental data correction, and screening out a (MgCoNiCuZn) O component proportion of which the phase change temperature is close to a silver melting point and the single-phase enthalpy value is high; secondly, dynamically simulating wetting behaviors of liquid silver and O with different component proportions (MgCoNiCuZn) through molecular dynamics, and selecting a component proportion with the best wettability with the liquid silver in combination with phase boundary energy calculation and wetting angle experimental verification; and finally, preparing a sample based on spark plasma sintering, actually measuring a wetting angle by using a seat drop method, and feeding back and correcting simulation parameters to form closed-loop optimization. The method is suitable for wettability collaborative optimization screening of a rare earth element doped high-entropy oxide system and liquid metal, proper components can be efficiently and accurately screened out, and the performance of the silver-based electric contact material is improved.

Description

Technical Field

[0001] The invention relates to the field of computational material science and technology, and in particular to a method for screening components of a high-entropy ceramic phase change-reinforced silver-based electrical contact material. Background Art

[0002] In modern electrical systems, electrical contact materials are vital components, widely used in high and low voltage electrical appliances, electronic equipment, power transmission and distribution, and other fields, and undertake the key tasks of conducting and 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 long been widely used due to their excellent electrical conductivity, thermal conductivity and arc erosion resistance. However, as electrical equipment develops towards high voltage, high current, high frequency and miniaturization, higher requirements are placed on the performance of electrical contact materials, and traditional silver-based electrical contact materials have gradually exposed some shortcomings.

[0004] Problems faced by traditional silver-based electrical contact materials: Insufficient hardness and wear resistance: During frequent electrical contact, friction and wear between contacts will cause the material surface to become rough, increase contact resistance, and generate excessive heat, accelerate material damage, and reduce the reliability of electrical contact; Poor resistance to welding: When a short circuit or overload occurs in the circuit, the arc generated by the large current will cause the contact surface to partially melt, which can easily cause the contacts to weld together, making it impossible to cut off the circuit normally, causing serious safety accidents; Limited resistance to arc erosion: The high temperature and high energy of the arc will cause erosion on the surface of the electrical contact material, causing changes in the composition and structure of the material, thus affecting the stability of its performance and service life; Limitations of existing screening methods: Insufficiency of single simulation method: Some studies use single simulation method, such as molecular dynamics simulation or first principle calculation. Although it can predict certain properties of materials to a certain extent, it ignores the multi-scale characteristics of materials and the complex situations in practical applications. There is a large deviation between the simulation results and the actual situation. The selected component ratio often cannot achieve the expected performance improvement effect in practical applications. 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.

[0005] 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

[0006] 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.

[0007] To achieve the above object, the present invention provides the following technical solutions: A method for screening components of high entropy ceramic phase change strengthened silver-based electrical contact materials, comprising the following steps: 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; 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; 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.

[0008] As a preferred solution, the specific technical path of step S1 includes: Crystal model construction and modification: Monte Carlo method is used 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 were corrected by least squares fitting to ensure that the lattice error between the model and the experimental one was less than 0.5%; First principles calculations: Based on density functional theory DFT, plane wave pseudopotential and generalized gradient approximation GGA are used to calculate the free energy, electronic state density and phonon spectrum of different component ratios; Multi-objective optimization algorithm: The component ratio is optimized by an improved genetic algorithm, and the objective function is: ,in, is the component ratio vector, expressed in atomic percentage, including ; The component ratio is The free energy change of the material when The component ratio is The phase transition temperature of the material; is the melting point of silver, which is 960°C; The component ratio is The predicted wetting angle between liquid silver and the material; is the target wetting angle that you want to achieve; , , is the dynamic weight coefficient, which is determined by sensitivity analysis; Screening criteria: Output candidate ratios with phase transition temperatures in the range of 900°C-1000°C and single-phase enthalpy values ​​higher than 200 kJ / mol.

[0009] As a preferred solution, the specific technical path of step S2 includes: Interface model construction: A (MgCoNiCuZn)O surface model with a fixed underlying lattice was constructed, with the shortest side length of the surface being greater than twice the diameter of the liquid silver sphere, and the geometry was optimized to allow the atoms to relax to the lowest energy state; Molecular dynamics simulation: In Material Studio software, the Compass force field is used to simulate the wetting behavior of liquid silver and high entropy ceramics. The specific steps include: High-temperature disordering: Ag is heated to 1200 °C in the NVT ensemble to simulate the liquid state; Relaxation process: long-term relaxation of more than 100ps at the target temperature (960℃±50℃); Quantification of Wettability: Extraction via trajectory file Droplet morphology, calculation of wetting angle ; Calculation of phase boundary energy : ,in, is the free energy of the composite system consisting 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 interface area between high entropy ceramic and liquid silver; Adaptive correction of force field parameters: If the elastic modulus of simulation and experiment deviates , adjust the force field parameters according to the following formula: ,in, is the corrected force field parameter; is the initial force field parameter; is the deviation between the elastic modulus obtained by simulation and the elastic modulus measured experimentally, expressed as a percentage; is the allowable elastic modulus deviation threshold, and the initial setting value is 5%.

[0010] As a preferred solution, the specific technical path of step S3 includes: Sample preparation: Spark plasma sintering (SPS) technology was used to prepare (MgCoNiCuZn)O ceramic sheets with different component ratios at a temperature of 50°C / min to 1500°C and a pressure of 50MPa in a vacuum environment. Wettability test: The wetting angle of liquid silver on the surface of ceramic wafer was tested under argon protection using the sessile drop method, and the experimental temperature range was 900℃-1000℃; Parameter closed loop correction: The measured wetting angle was compared with the simulation result. If the deviation was >5%, the temperature control method, step size and thickness of the interface diffusion layer in the molecular dynamics simulation were adjusted.

[0011] As a preferred solution, the screening target of the high entropy ceramic component ratio is: The deviation between the phase transition temperature and 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 Less than 0.8J / m²; The component ratio range is limited to: Mg:Co:Ni:Cu:Zn=(5-20):(10-25):(15-30):(10-20):(5-15).

[0012] As a preferred solution, in the Monte Carlo molecular dynamics simulation, the initial proportion of virtual atoms is generated by uniform distribution, and the atomic replacement is accepted or rejected by the Metropolis criterion, and the energy convergence threshold is 0.01 eV / atom.

[0013] As a preferred solution, the dynamic weight coefficient , , The adjustment rules are: When the free energy change When the sensitivity is higher than other parameters, Improved to 0.8; When the phase change temperature deviation When the temperature exceeds 30℃, Increased to 0.6; When the wetting angle deviation exceeds 10°, Improved to 1.0.

[0014] As a preferred solution, the allowable elastic modulus deviation threshold Dynamic adjustment based on the complexity of the material system: For five-element high entropy oxides, Set to 5%; For high entropy systems with rare earth elements added, Relaxed to 8%.

[0015] It can be seen from the technical solution provided by the present invention that the method for screening components of a high entropy ceramic phase change strengthened silver-based electrical contact material provided by the present invention has the following beneficial effects: Efficient and accurate screening: The present invention combines a variety of advanced computing methods such as first-principles calculations and Monte Carlo molecular dynamics simulations to deeply study the structure, performance and interaction of materials at the atomic scale, and accurately predict key performance parameters such as phase transition temperature, free energy, and wettability of materials. Through a multi-objective optimization algorithm, multiple performance indicators are comprehensively considered and weight coefficients are dynamically adjusted, which greatly improves the efficiency and accuracy of screening and can quickly screen out the most potential combination from a large number of possible component ratios. A closed-loop optimization process of "calculation-experiment-correction" has been formed; the simulation results provide theoretical guidance for the experiment, and the experimental data are fed back to correct the simulation parameters, so that the screening process is continuously optimized to ensure that the final selected component ratio has good performance in practical applications; this method avoids the blindness and inefficiency of traditional screening methods and saves a lot of time and experimental costs; Enhanced electrical contact performance: The selected high-entropy ceramic components can significantly improve the hardness and wear resistance of silver-based electrical contact materials after being combined with silver-based materials. The unique multi-principal component structure and high-entropy effect of high-entropy ceramics give them high hardness. Dispersed in the silver matrix, they can effectively resist friction and wear, reduce material loss during electrical contact, and extend the service life of electrical contact materials. The material's resistance to welding is optimized. During the electrical contact process, an arc is generated when current passes through the contacts, which may cause the contacts to weld together. Suitable 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 and improving the reliability and stability of the electrical contact. Improved arc erosion resistance of materials; high entropy ceramics have good chemical stability and high temperature performance, can remain stable under high temperature of arc, reduce the degree of arc erosion of silver-based materials, and ensure the stability of performance of electrical contact materials during long-term use; Improve conductivity: Although high-entropy ceramics themselves have relatively poor conductivity, by accurately screening the proportion of components, high-entropy ceramics can exist in silver-based materials in a suitable form and distribution, while enhancing other properties and minimizing the impact on conductivity; and the good interface bonding between high-entropy ceramics and silver base helps the transmission of electrons, and to a certain extent may even improve the conductive uniformity of the material and improve the overall conductive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention 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. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is 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 intended to limit the present invention.

[0018] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0019] like Figure 1 As 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, comprising the following steps: 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; 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; 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.

[0020] In this embodiment, step S1 aims to preliminarily screen out the component ratios with phase transition temperature close to the silver melting point and high single-phase enthalpy value from many possible (MgCoNiCuZn)O component ratios through theoretical calculation and simulation combined with experimental data correction; this helps to narrow the scope of subsequent screening, improve screening efficiency, and lay the foundation for obtaining high-entropy ceramic phase change strengthened silver-based electrical contact materials with excellent performance; As the starting step of the entire component screening method, it provides potential candidate component ratios for subsequent interface feature screening and experimental and simulation coordinated optimization; through the preliminary control of the phase thermophysical properties, it ensures that the components of subsequent research match the application requirements of silver-based electrical contact materials in terms of thermodynamics and phase change properties; Step S1 uses a method combining first-principles calculation and Monte Carlo molecular dynamics simulation, and makes corrections based on experimental data. This comprehensive application of multiple scales and methods can more accurately predict the phase thermal physical properties of materials and improve the accuracy of screening. At the same time, a multi-objective optimization algorithm is introduced to comprehensively consider multiple factors such as free energy, phase transition temperature and predicted wetting angle, dynamically adjust the weight coefficient, and achieve more scientific and efficient screening of component ratios. The detailed steps of step S1 include: S1-1: Crystal model construction and modification: S1-1-1: Model generation: The Monte Carlo method is used to randomly generate high entropy oxide crystal models with different component ratios. The Monte Carlo method is based on the principle of probability statistics and can explore the possibility of crystal structures under different component ratios in a large number of random attempts, providing a variety of initial models for subsequent precise calculations. S1-1-2: Model correction: Combined with the measured XRD full spectrum data, the lattice constant, atomic occupancy and defect concentration are corrected by least squares fitting. The least squares method is a mathematical optimization technique that finds the best function match for the data by minimizing the sum of squares of errors. In this way, the error between the model and the experimental lattice is ensured to be less than 0.5%, making the constructed crystal model closer to the structure of the actual material. S1-2: First principles calculations: Based on density functional theory (DFT), plane wave pseudopotential and generalized gradient approximation (GGA) are used to calculate the free energy, electronic state density and phonon spectrum of different component ratios; Density functional theory is a quantum mechanical method to study the electronic structure of multi-electron systems, and plane wave pseudopotential and generalized gradient approximation are its common implementation methods; through these calculations, we can deeply understand the thermodynamic properties and electronic structure of materials under different component ratios, providing a theoretical basis for subsequent optimization; S1-3: Multi-objective optimization algorithm: S1-3-1: Objective function setting: Optimize the component ratio through the improved genetic algorithm, and the objective function is: ,in, is the component ratio vector, expressed in atomic percentage, (e.g. ); The component ratio is The free energy change of the material when The component ratio is The phase transition temperature of the material; is the melting point of silver, which is 960°C; The component ratio is The predicted wetting angle between liquid silver and the material; is the target wetting angle that you want to achieve; , , is the dynamic weight coefficient, which is determined by sensitivity analysis. The objective function comprehensively considers three key factors: free energy, phase transition temperature and predicted wetting angle to achieve multi-objective optimization of component ratio. S1-3-2: Dynamic weight adjustment: Dynamically adjust the weight coefficient according to the sensitivity and deviation of different parameters , , ; When the free energy change When the sensitivity of is higher than other parameters (i.e., phase change temperature deviation and wetting angle deviation), Increase to 0.8; when the phase change temperature deviation When the temperature exceeds 30℃, Increase to 0.6; when the wetting angle deviation exceeds 10°, Improved to 1.0; this dynamic adjustment mechanism can highlight key factors according to actual conditions and improve the pertinence and accuracy of optimization; S1-4: Determination of screening criteria: Output candidate ratios with phase transition temperatures in the range of 900°C-1000°C and single-phase enthalpy values ​​higher than 200 kJ / mol; this screening criterion ensures that the component ratios initially screened out are close to the melting point of silver in terms of phase transition temperature and have a higher single-phase enthalpy value, which is conducive to the subsequent formation of a good composite system with silver-based materials and improves the performance of electrical contact materials.

[0021] Further, step S2 uses molecular dynamics simulation and phase boundary energy calculation, combined with wetting angle experimental verification, to deeply explore the interface interaction between liquid silver and different component ratios (MgCoNiCuZn)O, and accurately screen out the component ratio with the best wettability with liquid silver; good wettability helps to improve the bonding strength and interface stability between high entropy ceramics and silver-based materials, thereby improving the overall performance of silver-based electrical contact materials, such as conductivity, arc erosion resistance, etc.; Based on the preliminary screening of the component ratio with suitable phase thermophysical properties in step S1, step S2 focuses on the interface characteristics of the material; the interface 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 change strengthened silver-based electrical contact materials, and further optimizes the microstructure and performance of the material; The molecular dynamics simulation technology can be used to observe the wetting behavior of liquid silver and high entropy ceramics in real time at the atomic scale. Combined with the precise calculation and experimental verification of the phase boundary energy, a complete set of interface performance evaluation methods has been formed. At the same time, the 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, which effectively improves the accuracy of the simulation and makes the screening results more in line with the actual situation. The detailed steps of step S2 include: S2-1: Interface model construction: S2-1-1: Model design: Construct a (MgCoNiCuZn)O surface model with a fixed underlying lattice, and the shortest side length of the surface is greater than twice the diameter of the liquid silver ball (≥20nm); this design is to ensure that during the simulation process, the liquid silver ball and the high-entropy ceramic surface have enough interaction space to avoid the influence of boundary effects, so that the simulation results can better reflect the real interface conditions; S2-1-2: Geometry optimization: Optimize the geometry of the constructed surface model to relax the atoms to the lowest energy state. In this process, the atoms will adjust their positions according to the mutual forces, and finally reach a relatively stable energy state, thus obtaining a more realistic interface model structure. S2-2: Molecular dynamics simulation: S2-2-1: High-temperature disordering: In MaterialStudio software, the Compass force field is used to simulate the wetting behavior of liquid silver and high-entropy ceramics. First, Ag is heated 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 a liquid state, which provides a basis for the subsequent simulation of the interaction between liquid silver and high-entropy ceramics. S2-2-2: Relaxation process: adjust the temperature to the target temperature (960℃±50℃) and perform a long relaxation of more than 100ps; during this process, the system will gradually reach a state of equilibrium, so that the simulation results can better reflect the real thermodynamic and kinetic properties; long-term relaxation can ensure that the movement and distribution of atoms are stable, thereby more accurately simulating the wetting behavior of liquid silver on the surface of high-entropy ceramics; S2-3: Wettability Quantification: S2-3-1: Wetting angle calculation: Extract the Ag droplet morphology through the trajectory file and calculate the wetting angle ; The wetting angle is an important indicator for measuring wettability, which reflects the degree of spreading of liquid silver on the surface of high entropy ceramics; by analyzing the atomic trajectories recorded during the simulation process, the shape and contact angle of the droplet can be determined, thereby obtaining the value of the wetting angle; S2-3-2: Calculation of phase boundary energy: Calculation of phase boundary energy , the formula is: ,in, is the free energy of the composite system consisting 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 interface area between high entropy ceramics and liquid silver; the interfacial energy reflects the stability of the interface. A lower interfacial energy indicates a tighter interface, which is beneficial to improving the performance of the material. S2-4: Adaptive correction of force field parameters: S2-4-1: Deviation judgment: Compare the elastic modulus obtained by simulation with the elastic modulus measured experimentally and calculate the deviation ,like , indicating that there is a large difference between the simulation results and the experimental results, and the force field parameters need to be corrected; S2-4-2: Parameter adjustment: Adjust the force field parameters according to the following formula: ,in, is the corrected force field parameter; is the initial force field parameter; is the deviation between the elastic modulus obtained by simulation and the elastic modulus measured experimentally, expressed as a percentage; is the allowable elastic modulus deviation threshold, and the initial setting value is 5%. Through this adaptive correction mechanism, the simulation results can be made closer to the experimental values, thereby 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.

[0022] Furthermore, step S3 forms a closed-loop optimization process by combining simulation with experiment; on the one hand, actual samples are prepared by spark plasma sintering, and accurate wetting angle experimental data are obtained by 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 high-entropy ceramic component ratio with better comprehensive performance can be screened out, providing a solid guarantee for the preparation of high-performance high-entropy ceramic phase change strengthened silver-based electrical contact materials; based on the preliminary screening of suitable phase thermophysical property component ratios in step S1 and the further screening of component ratios 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, so that subsequent simulations can more accurately predict material properties, providing an important basis for the final determination of the optimal component ratio, and ensuring the scientificity and effectiveness of the entire screening method; 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 synergy of simulation and experiment is achieved, greatly improving the screening efficiency and accuracy; at the same time, this closed-loop optimization process has good versatility and scalability, and is suitable for material screening and performance optimization of different systems; The specific operation steps of step S3 are as follows: S3-1: Sample preparation: S3-1-1: Raw material preparation: Prepare the corresponding (MgCoNiCuZn)O raw material powder according to the proportions of different components screened out in steps S1 and S2; ensure that the purity and particle size of the raw materials meet the requirements of spark plasma sintering to ensure uniform quality of the prepared ceramic sheets; S3-1-2: Mold filling: The prepared raw material powder is loaded into a specific mold. The choice of the mold should be determined according to the size and shape of the required ceramic piece. During the mold filling process, attention should be paid to the uniform distribution of the powder to avoid local density differences. S3-1-3: Spark plasma sintering (SPS): Sintering is performed in a vacuum environment using spark plasma sintering technology; the temperature is raised to 1500°C at a heating rate of 50°C / min, while a pressure of 50MPa is applied; during the sintering process, the high temperature and high pressure generated by the discharge plasma can promote the rapid sintering and densification of the powder particles, thereby preparing (MgCoNiCuZn)O ceramic sheets with good performance; after sintering, the ceramic sheets are cooled to room temperature with the furnace and taken out for use; S3-2: Wettability test: S3-2-1: Sample pretreatment: Surface treatment of the prepared ceramic sheet, such as grinding and polishing, is performed to obtain a flat and clean surface to ensure the accuracy of the experimental results; at the same time, the silver block is processed into a suitable size as a source of liquid silver; S3-2-2: Sessile drop method experiment: Use the sessile drop method to test the wetting angle of liquid silver on the surface of the ceramic sheet under argon protection; place the ceramic sheet in a high-temperature furnace and heat it to the experimental temperature range (900℃-1000℃), then place a silver block on the surface of the ceramic sheet to melt it to form liquid silver droplets; use a high-speed camera and other equipment to record the spreading process of the liquid silver droplets on the surface of the ceramic sheet until it reaches a state of equilibrium; finally, 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 sheet; S3-3: Parameter closed loop correction: S3-3-1: Result comparison: Compare the wetting angle measured by the sessile drop method with the predicted wetting angle obtained by molecular dynamics simulation, and calculate the deviation between the two. If the deviation exceeds 5%, it means that there is a large difference between the simulation result and the actual situation, and the simulation parameters need to be adjusted. S3-3-2: Parameter adjustment: According to the deviation, adjust the relevant parameters in the molecular dynamics simulation; specifically, change the temperature control method from Berendsen to Nose-Hoover. The Nose-Hoover temperature control method can more accurately simulate the temperature fluctuation of the system and improve the accuracy of temperature control; adjust the step size from 1fs to 0.5fs. Reducing the step size can improve the accuracy of the simulation, but it will increase the calculation time; increase the thickness of the interface diffusion layer to 2nm to more accurately simulate the interface diffusion behavior between liquid silver and high entropy ceramics; 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 results and the experimental data is within an acceptable range; through this closed-loop correction mechanism, the simulation parameters are continuously optimized to improve the accuracy and reliability of the simulation, thereby screening out a high-entropy ceramic component ratio that better meets actual needs.

[0023] In this embodiment, in the Monte Carlo molecular dynamics simulation, the initial proportion of virtual atoms is generated by uniform distribution, and the atomic replacement is accepted or rejected by the Metropolis criterion, and the energy convergence threshold is 0.01 eV / atom.

[0024] The present invention will be further described below in conjunction with specific embodiments: 1. Experimental materials and equipment: Material: 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; Silver blocks with a purity of 99.99% were used for wettability experiments; equipment: Planetary ball mill: used for mixing and refining raw material powders; Spark plasma sintering furnace (SPS): used to prepare (MgCoNiCuZn)O ceramic sheets; High temperature furnace: equipped with argon protection device, used for sessile drop wettability experiment; Scanning electron microscope (SEM): used to observe the microstructure of samples; X-ray diffractometer (XRD): used to analyze the crystal structure of samples; Molecular dynamics simulation software: MaterialStudio; 2. Implementation steps: Step S1: Preliminary screening of phase thermal physical properties: S1-1: Crystal model construction and modification: Model generation: Using the Monte Carlo method, 100 (MgCoNiCuZn)O high entropy oxide crystal models with different component ratios were randomly generated on the computer; the component ratio range was set to Mg:Co:Ni:Cu:Zn=(5-20):(10-25):(15-30):(10-20):(5-15) (atomic percentage); Model correction: The above 100 kinds of raw material powders were weighed in corresponding proportions and ball-milled in a planetary ball mill at a speed of 300 r / min for 12 h to fully mix the powders; then an XRD test was performed to obtain the measured XRD full spectrum data; the lattice constant, atomic occupancy and defect concentration of the crystal model were corrected using the least squares fitting method to ensure that the lattice error between the model and the experimental one was less than 0.5%; S1-2: First principles calculation: Based on density functional theory (DFT), plane wave pseudopotential and generalized gradient approximation (GGA) were used to calculate the 100 modified crystal models using corresponding calculation software to obtain the free energy, electronic state density and phonon spectrum of different component ratios; during the calculation process, the plane wave cutoff energy was set to 500eV, and the Brillouin zone k-point grid was set to 4×4×4; S1-3: Multi-objective optimization algorithm: Objective function setting: The component ratio is optimized by improved genetic algorithm, and the objective function is: ,in, is the component ratio vector, expressed in atomic percentage, (e.g. ); The component ratio is The free energy change of the material when The component ratio is The phase transition temperature of the material; is the melting point of silver, which is 960°C; The component ratio is The predicted wetting angle between liquid silver and the material; is the target wetting angle that you want to achieve; , , is the dynamic weight coefficient, and its initial values ​​are set to 0.3, 0.3, and 0.4 respectively; Dynamic weight adjustment: During the optimization process, the sensitivity and deviation of each parameter are monitored in real time; when the free energy changes When the sensitivity of is higher than other parameters (i.e., phase change temperature deviation and wetting angle deviation), Increase to 0.8; when the phase change temperature deviation When the temperature exceeds 30℃, Increase to 0.6; when the wetting angle deviation exceeds 10°, Improved to 1.0; Optimization calculation: After 50 generations of genetic algorithm iterative calculation, the optimal component ratio that meets the objective function is screened out; S1-4: Screening criteria determination: From the above optimization results, 10 candidate component ratios with phase transition temperatures in the range of 900℃-1000℃ and single-phase enthalpy values ​​higher than 200kJ / mol are output; Step S2: Further screening of interface features: S2-1: Interface model construction: Model design: For the above 10 candidate component ratios, a (MgCoNiCuZn)O surface model with a fixed underlying lattice was constructed, and the shortest side length of the surface was set to 25nm; Geometry optimization: Use the geometry optimization module in MaterialStudio software to optimize the surface model so that the atoms relax to the lowest energy state. During the optimization process, the Smart algorithm is used and the convergence accuracy is set to Fine. S2-2: Molecular dynamics simulation: High-temperature disordering: In MaterialStudio software, the Compass force field is used to heat Ag atoms to 1200°C in the NVT ensemble to simulate liquid silver. During the heating process, the heating rate is set to 10K / ps and the duration is 50ps. Relaxation process: The temperature was adjusted to 960°C and a long relaxation of 150 ps was performed to allow the system to reach equilibrium. During the relaxation process, the time step was set to 1 fs. S2-3: Wettability Quantification: Wetting angle calculation: The trajectory file obtained by simulation is used to extract the Ag droplet morphology and calculate the wetting angle using the analysis tools in the software ; Phase boundary energy calculation: Calculate the phase boundary energy , the formula is: ,in, is the free energy of the composite system consisting 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 interface area between high entropy ceramic and liquid silver; S2-4: Adaptive correction of force field parameters: Deviation judgment: Compare the elastic modulus obtained by simulation with the experimental elastic modulus of similar systems in relevant literature and calculate the deviation ,like , then the force field parameters are corrected; Parameter adjustment: Adjust the force field parameters according to the following formula: ,in, is the corrected force field parameter; is the initial force field parameter; is the deviation between the elastic modulus obtained by simulation and the elastic modulus measured experimentally, expressed as a percentage; The initial setting value is 5% for the allowable elastic modulus deviation threshold. The molecular dynamics simulation is performed again using the modified force field parameters until the deviation between the simulated and experimental elastic moduli is within 5%. Finally, the three component ratios with the best wettability with liquid silver are screened out. Step S3: Experimental and simulation collaborative optimization: S3-1: Sample preparation: Raw material preparation: according to the proportion of the three components screened out, accurately weigh the corresponding MgO, CoO, NiO, CuO and ZnO powders; Mold filling: put the weighed powder into the graphite mold, and the powder filling should be uniform; Spark plasma sintering (SPS): In a vacuum environment, the temperature was raised to 1500°C at a heating rate of 50°C / min, and a pressure of 50MPa was applied. After the temperature and pressure were kept for 10 minutes, the (MgCoNiCuZn)O ceramic sheets with three different component ratios were prepared. S3-2: Wettability test: Sample pretreatment: The prepared ceramic sheet was ground and polished to make its surface roughness reach Ra≤0.1μm; Sessile drop method experiment: Place the ceramic sheet in a high-temperature furnace, introduce argon gas for protection, and raise the temperature to 950°C at a heating rate of 20°C / min; Place a silver block on the surface of the ceramic sheet to melt it to form liquid silver droplets; Use a high-speed camera to record the spreading process of the liquid silver droplets on the surface of the ceramic sheet for 10 minutes; 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 sheet; S3-3: Parameter closed loop correction: Result comparison: The wetting angle measured by the sessile drop method is compared with the predicted wetting angle obtained by molecular dynamics simulation, and the deviation between the two is calculated; if the deviation exceeds 5%, the parameters are adjusted; Parameter adjustment: Change the temperature control method in the molecular dynamics simulation from Berendsen to Nose-Hoover, adjust the step size from 1fs to 0.5fs, and increase the thickness of the interface diffusion layer to 2nm; 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 results and the experimental data is within 5%; finally determine the high-entropy ceramic component ratio with the best performance; 3. Result analysis: Microstructure Analysis: The microstructure of the high entropy ceramic phase change strengthened silver-based electrical contact material samples finally selected was observed using a scanning electron microscope (SEM) to analyze the interface bonding and distribution state between the high entropy ceramic and the silver base. Performance Test: The samples were tested for conductivity, hardness, arc erosion resistance and other properties to evaluate the practical application performance of the materials. The results showed that the materials obtained by the component screening method of the present invention have significant improvements in various performance indicators and meet the requirements for the use of high-entropy ceramic phase change strengthened silver-based electrical contact materials.

[0025] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for screening components of high entropy ceramic phase change strengthened silver-based electrical contact materials, characterized in that: The following steps are involved: 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; 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; 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.

2. The method for selecting components of a high entropy ceramic phase change strengthened silver-based electrical contact material according to claim 1, characterized in that: The specific technical path of step S1 includes: Crystal model construction and modification: Monte Carlo method is used 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 were corrected by least squares fitting to ensure that the lattice error between the model and the experimental one was less than 0.5%; First principles calculations: Based on density functional theory DFT, plane wave pseudopotential and generalized gradient approximation GGA are used to calculate the free energy, electronic state density and phonon spectrum of different component ratios; Multi-objective optimization algorithm: The component ratio is optimized by an improved genetic algorithm, and the objective function is: ,in, is the component ratio vector, expressed in atomic percentage, including ; The component ratio is The free energy change of the material when The component ratio is The phase transition temperature of the material; is the melting point of silver, which is 960°C; The component ratio is The predicted wetting angle between liquid silver and the material; is the target wetting angle that you want to achieve; , , is the dynamic weight coefficient, which is determined by sensitivity analysis; Screening criteria: Output candidate ratios with phase transition temperatures in the range of 900°C-1000°C and single-phase enthalpy values ​​higher than 200 kJ / mol.

3. The method for selecting components of a high entropy ceramic phase change strengthened silver-based electrical contact material according to claim 2, characterized in that: The specific technical path of step S2 includes: Interface model construction: A (MgCoNiCuZn)O surface model with a fixed underlying lattice was constructed, with the shortest side length of the surface being greater than twice the diameter of the liquid silver sphere, and the geometry was optimized to allow the atoms to relax to the lowest energy state; Molecular dynamics simulation: In Material Studio software, the Compass force field is used to simulate the wetting behavior of liquid silver and high entropy ceramics. The specific steps include: High-temperature disordering: Ag is heated to 1200 °C in the NVT ensemble to simulate the liquid state; Relaxation process: long-term relaxation of more than 100ps at the target temperature (960℃±50℃); Quantification of Wettability: Extraction via trajectory file Droplet morphology, calculation of wetting angle ; Calculation of phase boundary energy : ,in, is the free energy of the composite system consisting 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 interface area between high entropy ceramic and liquid silver; Adaptive correction of force field parameters: If the simulated and experimental elastic moduli deviate , adjust the force field parameters according to the following formula: ,in, is the corrected force field parameter; is the initial force field parameter; is the deviation between the elastic modulus obtained by simulation and the elastic modulus measured experimentally, expressed as a percentage; is the allowable elastic modulus deviation threshold, and the initial setting value is 5%.

4. The method for selecting components of high entropy ceramic phase change strengthened silver-based electrical contact materials according to claim 3, characterized in that: The specific technical path of step S3 includes: Sample preparation: Spark plasma sintering (SPS) technology was used to prepare (MgCoNiCuZn)O ceramic sheets with different component ratios at a temperature of 50°C / min to 1500°C and a pressure of 50MPa in a vacuum environment. Wettability test: The wetting angle of liquid silver on the surface of ceramic wafer was tested under argon protection using the sessile drop method, and the experimental temperature range was 900℃-1000℃; Parameter closed loop correction: The measured wetting angle was compared with the simulation result. If the deviation was >5%, the temperature control method, step size and thickness of the interface diffusion layer in the molecular dynamics simulation were adjusted.

5. The method for selecting components of high entropy ceramic phase change strengthened silver-based electrical contact materials according to claim 4, characterized in that: The screening target of the high entropy ceramic component ratio is: The deviation between the phase transition temperature and 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 Less than 0.8J / m²; The component ratio range is limited to: Mg:Co:Ni:Cu:Zn=(5-20):(10-25):(15-30):(10-20):(5-15).

6. A method for selecting components of high entropy ceramic phase change strengthened silver-based electrical contact materials according to claim 5, characterized in that: In the Monte Carlo molecular dynamics simulation, the initial proportion of virtual atoms is generated by uniform distribution, and atomic replacement is accepted or rejected by the Metropolis criterion, with an energy convergence threshold of 0.01 eV / atom.

7. A method for selecting components of high entropy ceramic phase change strengthened silver-based electrical contact materials according to claim 6, characterized in that: The dynamic weight coefficient , , The adjustment rules are: When the free energy change When the sensitivity is higher than other parameters, Improved to 0.8; When the phase change temperature deviation When the temperature exceeds 30℃, Increased to 0.6; When the wetting angle deviation exceeds 10°, Improved to 1.

0.

8. The method for selecting components of high entropy ceramic phase change strengthened silver-based electrical contact materials according to claim 7, characterized in that: The allowable elastic modulus deviation threshold Dynamic adjustment based on the complexity of the material system: For five-element high entropy oxides, Set to 5%; For high entropy systems with rare earth elements added, Relaxed to 8%.

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