A performance simulation method and system based on the phase change process of silicon nitride ceramics

Abstract

The present invention belongs to the technical field of ceramic material properties, and provides a performance simulation method and system based on the phase transition process of silicon nitride ceramics, which are divided into a simulation part and an application part. During the simulation process, in view of the phenomenon that silicon nitride will change from the α phase to the β phase as the pressure and temperature increase during the experiment, the simulation is used to calculate the pressure and temperature of the phase transition. According to the basis that the Gibbs free energy G is equal when the phase transition occurs in the two-phase materials, the intersection point is found, and the conditions at this point are the phase transition points; the changes in the mechanical properties and thermodynamic properties of the two-phase materials with the increase of pressure and temperature and the occurrence of phase transition are studied.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic material properties, and particularly relates to a method and system for simulating the properties based on the phase transformation process of silicon nitride ceramics. Background Art

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Due to the characteristics of silicon nitride materials such as high chemical stability, high temperature resistance, thermal shock resistance, high hardness, and good mechanical properties. Therefore, it has a wide range of applications in the microelectronics industry, mechanical industry, automotive industry, solar cells, ceramic cutting tools, etc.

[0004] The excellent properties of silicon nitride ceramics have special application values for working environments with high temperature, high speed, and strong corrosive media. At normal temperature and pressure, there are two polymorphs, namely α-Si3N4 and β-Si3N4. In nature, α-Si3N4 exists in a rare mineral (nitrite) and meteorites. During the sintering process of silicon nitride-based ceramic materials such as ceramic cutting tools, α-phase silicon nitride will transform into β-phase silicon nitride with the increase of pressure and temperature.

[0005] The existing technology for the research of the above materials is still limited to macroscopic or microscopic analysis, and it is impossible to directly combine macroscopic and microscopic analysis of the relationship between the changes in structure, mechanical properties, and thermodynamic properties during the phase transformation process. Therefore, it is impossible to determine the optimal sintering pressure and temperature of the best ceramic materials, avoiding the blind sintering of ceramic materials. Summary of the Invention

[0006] In order to solve at least one of the technical problems existing in the above background art, the present invention provides a method and system for simulating the properties based on the phase transformation process of silicon nitride ceramics, which uses molecular simulation technology to study the changes in structure, mechanical properties, and thermodynamic properties during the phase transformation process from α-Si3N4 to β-Si3N4 from a simulation perspective.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides a method for simulating the properties based on the phase transformation process of silicon nitride ceramics, including the following steps:

[0009] Including the following steps:

[0010] Obtain the lattice information of different phases of silicon nitride, and respectively construct the monomer unit cell structures of the corresponding phases of silicon nitride;

[0011] Respectively perform conformational optimization on all phase silicon nitride monomer unit cell structures under different pressure conditions;

[0012] Thermodynamic calculations and kinetic calculations are respectively carried out on all phases of silicon nitride after conformational optimization under different temperature conditions;

[0013] Thermodynamic performance analysis and kinetic performance analysis are respectively carried out on all phases of silicon nitride after kinetic calculation;

[0014] Based on the results of thermodynamic performance analysis and kinetic performance analysis, the optimal sintering pressure and temperature for the phase transformation of different phases of silicon nitride are determined, providing a theoretical basis for guiding the sintering of ceramic materials.

[0015] The second aspect of the present invention provides a performance simulation system based on the phase transformation process of silicon nitride ceramics, including:

[0016] A monomer unit cell structure construction module, configured to: obtain the lattice information of different phases of silicon nitride and respectively construct the monomer unit cell structures of the corresponding phases of silicon nitride;

[0017] A conformational optimization module, configured to: respectively carry out conformational optimization on the monomer unit cell structures of all phases of silicon nitride under different pressure conditions;

[0018] A thermodynamic and kinetic calculation module, configured to: respectively carry out thermodynamic calculations and kinetic calculations on all phases of silicon nitride after conformational optimization under different temperature conditions;

[0019] A ceramic sintering guidance module, configured to: respectively carry out thermodynamic performance analysis and kinetic performance analysis on all phases of silicon nitride after kinetic calculation;

[0020] Based on the results of thermodynamic performance analysis and kinetic performance analysis, the optimal sintering pressure and temperature for the phase transformation of different phases of silicon nitride are determined, providing a theoretical basis for guiding the sintering of ceramic materials.

[0021] The third aspect of the present invention provides a computer-readable storage medium.

[0022] A computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, it realizes the steps in a performance simulation method based on the phase transformation process of silicon nitride ceramics as described above.

[0023] The fourth aspect of the present invention provides a computer device.

[0024] A computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, it realizes the steps in a performance simulation method based on the phase transformation process of silicon nitride ceramics as described above.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] The present invention is divided into a simulation part and an application part. During the simulation process, in view of the phenomenon that silicon nitride will undergo a phase transformation from the α-phase to the β-phase as the pressure and temperature increase during the experiment, simulation is used to calculate the pressure and temperature of the phase transformation. According to the basis that the Gibbs free energy G is equal when the phase transformation occurs in the two-phase materials, the intersection point is found, and the conditions at this point are the phase transformation points; the changes in the mechanical properties and thermodynamic properties of the two-phase materials with the increase of pressure and temperature and the occurrence of phase transformation are studied.

[0027] In the application part, based on the changes in the mechanical properties and thermodynamic properties of the two-phase materials with the increase of pressure and temperature and the occurrence of phase transformation, the blind sintering of ceramic materials is avoided. Compared with the silicon nitride sintering experiment prepared under the same experimental conditions, a large amount of manpower and material resources are saved, the prediction of various properties during the sintering process of silicon nitride materials is realized, and a guiding basis is provided for the actual phase transformation sintering of silicon nitride.

[0028] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0029] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0030] Figure 1 It is a flow block diagram of the silicon nitride ceramic phase transformation simulation method in Embodiment 1 of the present invention;

[0031] Figures 2(a) - 2(b) It is the initial structure model of α-phase silicon nitride and β-phase silicon nitride in Embodiment 1 of the present invention;

[0032] Figures 3(a) - 3(b) It is the final structure model of α-phase silicon nitride and β-phase silicon nitride in Embodiment 1 of the present invention;

[0033] Figures 4(a) - 4(g) It is the analysis result of the thermodynamic properties under different temperature conditions at a pressure of 0 MPa in Embodiment 1 of the present invention;

[0034] Figures 5(a) - 5(b) It is the analysis result of the mechanical properties under different temperature conditions at a pressure of 0 MPa in Embodiment 1 of the present invention;

[0035] Figures 6(a) - 6(g) It is the analysis result of the thermodynamic properties under different temperature conditions at a pressure of 16 MPa in Embodiment 1 of the present invention;

[0036] Figures 7(a) - 7(b)It is the mechanical property analysis results under different temperature conditions at a pressure of 16 MPa in the first embodiment of the present invention;

[0037] Figures 8(a) - 8(g) It is the thermodynamic property analysis results under different temperature conditions at a pressure of 32 MPa in the first embodiment of the present invention;

[0038] Figures 9(a) - 9(b) It is the mechanical property analysis results under different temperature conditions at a pressure of 32 MPa in the first embodiment of the present invention. Detailed implementation manners

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further descriptions of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0041] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] Embodiment 1

[0043] As Figure 1 shown, this embodiment provides a performance simulation method based on the phase transition process of silicon nitride ceramics, including the following steps:

[0044] S101: Obtain the lattice information of silicon nitride in different phases, and respectively construct the monomer unit cell structures of silicon nitride corresponding to the respective phases;

[0045] S102: Respectively perform conformational optimizations on all the monomer unit cell structures of silicon nitride in different phases under different pressure conditions;

[0046] S103: Based on all the silicon nitride in different phases after conformational optimization, perform thermodynamic calculations and kinetic calculations under different temperature conditions;

[0047] S104: Respectively perform thermodynamic property analysis and kinetic property analysis on all the silicon nitride after kinetic calculations;

[0048] S105: Based on the results of thermodynamic property analysis and kinetic property analysis, determine the optimal sintering pressure and temperature for the phase transition of silicon nitride in different phases, providing a theoretical basis for guiding the sintering of ceramic materials.

[0049] The above process studied the effects of various pressures and temperatures on the changes in the structure, mechanical properties, and thermodynamic properties of silicon nitride, achieving a theoretical analysis of the phase transformation and mechanical properties of silicon nitride from a microscopic perspective and avoiding the blind sintering of ceramic materials.

[0050] In this embodiment, α-phase silicon nitride and β-phase silicon nitride are used as the research objects for illustration.

[0051] As Figures 2(a) - 2(b) shown, in S101, the obtaining of the lattice information of different-phase silicon nitrides and the construction of the monomer unit cell structures of the corresponding-phase silicon nitrides specifically include:

[0052] According to the lattice information of α-phase silicon nitride: α = β = 90°, γ = 120°, construct the monomer unit cell structure of α-phase silicon nitride;

[0053] According to the lattice information of β-phase silicon nitride: α = β = 90°, γ = 120°, construct the monomer unit cell structure of β-phase silicon nitride;

[0054] The above construction of each monomer unit cell structure can be achieved by software construction or by using corresponding construction algorithms, and can be specifically selected according to the actual situation. In this embodiment, the Visualizer interface of Materials Studio is selected for construction.

[0055] A unit cell is a parallelepiped unit that can completely reflect the chemical-structural characteristics of the atoms or ions inside a crystal in three-dimensional space. Among them, the one that can maintain the symmetry of the crystal structure and has the smallest volume is specifically called the "unit cell", but it is also often simply called the unit cell, and its specific shape and size are characterized by its three sets of edge lengths a, b, c and the inter-edge angles α, β, γ (collectively called the "unit cell parameters"), corresponding to the unit parallelepiped in the space lattice.

[0056] In S102, under different pressure conditions, the conformational optimization of all-phase silicon nitride monomer unit cell structures respectively includes:

[0057] Under different pressures, select the simulation method or software, set the accuracy, exchange-correlation functional, corresponding algorithms, Brillouin zone k-point sampling, and cut-off energy, etc., and perform conformational optimization on α-phase silicon nitride and β-phase silicon nitride respectively.

[0058] In specific embodiments, the pressures are set to 0, 16, and 32 MPa respectively. Using the CASTEP module in Materials Studio, the precision is selected as Ultrafine, the exchange-correlation functional is selected as the generalized gradient approximation PW91, the Algorithm is selected as BFGS, the Energy is selected as 5.0e-6 eV / atom, and the Force is selected as The Stress is selected as 0, 0.016, and 0.032 GPa, and the Maxdisplacement is selected as The Max iterations is selected as 1000; the SCF is selected as Ultrafine, the Brillouin zone k-point is selected as Fine, the cutoff energy is selected as 280 eV, and ultrasoft pseudopotentials are used to replace the interaction between the ionic core and valence electrons.

[0059] CASTEP is a set of advanced computational programs based on quantum mechanics. It uses the plane-wave ultrasoft pseudopotential method of density functional theory to perform first-principles quantum mechanics calculations and can be used to simulate the properties of solids, interfaces, and surfaces.

[0060] Energy specifies the convergence threshold for the maximum energy change during the geometry optimization process; Force specifies the convergence threshold for the maximum force; Stress specifies the convergence threshold for the maximum stress during the geometry optimization; Max displacement specifies the convergence threshold for the maximum displacement during the geometry optimization; Max iterations specifies the maximum number of geometry optimization cycles.

[0061] After the conformational optimization is completed, the lattice parameter information of α-phase silicon nitride and β-phase silicon nitride crystals has changed.

[0062] In S103, based on all phases of silicon nitride after conformational optimization, dynamic calculations are performed under different temperature conditions, including:

[0063] At different temperatures, analyzing from the elastic constants of silicon nitride, the performance change laws of α-phase silicon nitride in the temperature range of 873 K, 1073 K, 1273 K, and 1473 K and β-phase silicon nitride in the temperature range of 1273 K, 1473 K, 1673 K, 1873 K, and 2073 K are obtained.

[0064] At different temperatures, select the simulation algorithm or software, set the precision, exchange-correlation functional, Algorithm, ensemble, time step, total simulation time, SCF, Brillouin zone k-point sampling, and cutoff energy, etc., and perform dynamic calculations on α-phase silicon nitride and β-phase silicon nitride respectively.

[0065] In specific embodiments,

[0066] When performing kinetic calculations on α-phase silicon nitride, the CASTEP module in Materials Studio is used. The accuracy is selected as Ultrafine, the exchange-correlation functional is selected as PW91 in the generalized gradient approximation, the Algorithm is selected as BFGS, the ensemble is selected as NPT, the temperatures are selected as 873K, 1073K, 1273K, and 1473K respectively, the time step is 1 fs, and the total simulation time is 5 ps; the SCF is selected as Ultrafine, the k-point in the Brillouin zone is selected as Fine, the cutoff energy is selected as 280 eV, and ultrasoft pseudopotentials are used to replace the interaction between the ionic core and valence electrons.

[0067] When performing kinetic calculations on β-phase silicon nitride, the CASTEP module in Materials Studio is used. The accuracy is selected as Ultrafine, the exchange-correlation functional is selected as PW91 in the generalized gradient approximation, the Algorithm is selected as BFGS, the ensemble is selected as NPT, the temperatures are selected as 1273K, 1473K, 1673K, 1873K, and 2073K respectively, the time step is 1 fs, and the total simulation time is 5 ps; the SCF is selected as Ultrafine, the k-point in the Brillouin zone is selected as Fine, the cutoff energy is selected as 280 eV, and ultrasoft pseudopotentials are used to replace the interaction between the ionic core and valence electrons.

[0068] In S103, the thermodynamic calculations include:

[0069] The CASTEP module in Materials Studio is used. The accuracy is selected as Ultrafine, the exchange-correlation functional is selected as the generalized gradient approximation PW91, the SCF is selected as Ultra-fine, the k-point in the Brillouin zone is selected as Fine, the cutoff energy is selected as 770 eV, and norm-conserving pseudopotentials are used to replace the interaction between the ionic core and valence electrons.

[0070] In S104, the thermodynamic performance analysis includes: analyzing from the Debye temperature, entropy, enthalpy, and phonon spectrum curve respectively to obtain the free energies of α-phase silicon nitride and β-phase silicon nitride. The free energies at each pressure are respectively fitted to obtain the pressure and temperature at the phase transition point.

[0071] The kinetic performance analysis includes:

[0072] Calculate the mechanical properties of α-phase silicon nitride from the first temperature threshold of 873K to the phase transition point, and calculate the mechanical properties of β-phase silicon nitride from the phase transition point to the second temperature threshold of 2073K.

[0073] In this embodiment, the CASTEP module in Materials Studio is used. The precision is selected as Ultrafine, the exchange-correlation functional is selected as the generalized gradient approximation PW91, the SCF is selected as Ultra-fine, the Brillouin zone k-point is selected as Fine, the cut-off energy is selected as 250 eV, and ultrasoft pseudopotentials are used to replace the interaction between the ionic core and valence electrons.

[0074] The simulation results under different conditions are as follows:

[0075] (1) When simulating under different temperature conditions at a pressure of 0 MPa, the specific process is as follows:

[0076] After the conformational optimization is completed, the lattice parameter information of α-phase silicon nitride and β-phase silicon nitride crystals is as follows:

[0077] α-phase silicon nitride: α = β = 90°, γ = 120°

[0078] β-phase silicon nitride: α = β = 90°, γ = 120°

[0079] Thermodynamic performance analysis is carried out on α-phase silicon nitride and β-phase silicon nitride after the kinetic calculation respectively:

[0080] As shown in Figure 4(a), at a pressure of 0 MPa, there is no intersection point of the free energy of α-phase silicon nitride and β-phase silicon nitride, that is, there is no phase change under this pressure.

[0081] As Figures 4(b) - 4(d) shown, first analyze the thermodynamic performance of α-phase silicon nitride. Analyze from aspects such as Debye temperature, entropy, enthalpy, and heat capacity. The Debye temperature of α-phase silicon nitride first rises sharply with the increase of temperature. At 25 K, the Debye temperature is 929 K, then it decreases, starts to rise at 105 K, and then slowly rises with the increase of temperature to 1216 K. Both entropy and enthalpy are positive values and increase with the increase of temperature, while the free energy is a negative value and decreases with the increase of temperature. The heat capacity gradually increases with the increase of temperature and finally gradually tends to a horizontal line, with a value of about 163 cal / cell.K.

[0082] As Figures 4(e) - 4(g)As shown in the figure, the thermodynamic properties of β-phase silicon nitride are further analyzed, which are analyzed from aspects such as Debye temperature, entropy, enthalpy, and heat capacity. When the pressure is 0 MPa, the Debye temperature of β-phase silicon nitride first decreases rapidly with the increase of temperature. At 25 K, the Debye temperature is 815 K, then it decreases, starts to rise at 45 K, and then slowly rises with the increase of temperature to 1211 K. The entropy and enthalpy are both positive values and increase with the increase of temperature, while the free energy is a negative value and decreases with the increase of temperature. The heat capacity gradually increases with the increase of temperature and finally gradually tends to a horizontal line, with a value of about 81 cal / cell.K.

[0083] As Figures 5(a) - 5(b) shown, the kinetic properties of α-phase silicon nitride and β-phase silicon nitride after kinetic calculation are analyzed respectively. In this example, the changes in elastic constants are analyzed.

[0084] With the increase of temperature and the occurrence of phase transformation, the elastic constants of α-phase silicon nitride and β-phase silicon nitride change accordingly. For α-phase silicon nitride, C 11 , C 22 and C 33 all decrease with the increase of temperature, while for β-phase silicon nitride, C 11 , C 22 and C 33 all fluctuate greatly with the increase of temperature; for α-phase silicon nitride, C 44 , C 55 and C 66 first increase and then decrease with the increase of temperature, while for β-phase silicon nitride, C 44 , C 55 and C 66 all gradually increase with the increase of temperature.

[0085] (2) When simulations are carried out under different temperature conditions at a pressure of 16 MPa, the specific process is as follows:

[0086] After the conformational optimization is completed, the lattice parameter information of α-phase silicon nitride and β-phase silicon nitride crystals is as follows:

[0087] α-phase silicon nitride: α = β = 90°, γ = 120°

[0088] β-phase silicon nitride: α = β = 90°, γ = 120°

[0089] The thermodynamic properties of α-phase silicon nitride and β-phase silicon nitride after kinetic calculation are analyzed respectively:

[0090] As shown in Figure 6(a), when the pressure is 16 MPa, there is no intersection point in the free energy of α-phase silicon nitride and β-phase silicon nitride, that is, no phase transformation occurs under this pressure.

[0091] AsFigures 6(b) - 6(d) As shown in the figure, first analyze the thermodynamic properties of α-phase silicon nitride, and analyze them from aspects such as Debye temperature, entropy, enthalpy, and heat capacity. The Debye temperature of α-phase silicon nitride first rises sharply with the increase of temperature. At 25K, the Debye temperature is 972K, then it decreases, starts to rise at 105K, and then slowly rises with the increase of temperature to 1188K. Both entropy and enthalpy are positive values and increase with the increase of temperature, while the free energy is a negative value and decreases with the increase of temperature. The heat capacity gradually increases with the increase of temperature and finally gradually tends to a horizontal line, with a value of about 163 cal / cell.K.

[0092] As Figures 6(e) - 6(g) shown, then analyze the thermodynamic properties of β-phase silicon nitride, and analyze them from aspects such as Debye temperature, entropy, enthalpy, and heat capacity. When the pressure is 16MPa, the Debye temperature of β-phase silicon nitride first decreases rapidly with the increase of temperature. At 25K, the Debye temperature is 1075K, then it decreases, starts to rise at 45K, and then slowly rises with the increase of temperature to 1211K. Both entropy and enthalpy are positive values and increase with the increase of temperature, while the free energy is a negative value and decreases with the increase of temperature. The heat capacity gradually increases with the increase of temperature and finally gradually tends to a horizontal line, with a value of about 81 cal / cell.K.

[0093] As Figures 7(a) - 7(b) shown, respectively conduct mechanical property analysis on α-phase silicon nitride and β-phase silicon nitride after kinetic calculation. In this example, the change of elastic constants is analyzed.

[0094] With the increase of temperature and the occurrence of phase transformation, the elastic constants of α-phase silicon nitride and β-phase silicon nitride change accordingly. The C 11 , C 22 and C 33 of both α-phase silicon nitride and β-phase silicon nitride first decrease, then increase, and then decrease with the increase of temperature; the C 44 , C 55 and C 66 of α-phase silicon nitride first decrease and then increase with the increase of temperature, while the C 44 , C 55 and C 66 of β-phase silicon nitride gradually increase with the increase of temperature.

[0095] (3) When performing simulations under different temperature conditions at a pressure of 32MPa, the specific process is as follows:

[0096] After the conformational optimization is completed, the lattice parameter information of α-phase silicon nitride and β-phase silicon nitride crystals is as follows:

[0097] α-phase silicon nitride: α = β = 90°, γ = 120°

[0098] β-phase silicon nitride: α = β = 90°, γ = 120°

[0099] Thermodynamic performance analysis is respectively carried out on α-phase silicon nitride and β-phase silicon nitride after kinetic calculation:

[0100] As shown in Figure 8(a), when the pressure is 32 MPa, there is an intersection point between α-phase silicon nitride and β-phase silicon nitride at 1330 K, that is, a phase transformation occurs under the conditions of 32 MPa and 1330 K.

[0101] As Figures 8(b) - 8(d) shown, first analyze the thermodynamic performance of α-phase silicon nitride, and analyze it respectively from aspects such as Debye temperature, entropy, enthalpy and heat capacity. The Debye temperature of α-phase silicon nitride first rises sharply with the increase of temperature. At 25 K, the Debye temperature is 916 K, then it decreases, starts to rise at 105 K, and then slowly rises with the increase of temperature to 1186 K. Both entropy and enthalpy are positive values and increase with the increase of temperature, while the free energy is a negative value and decreases with the increase of temperature. The heat capacity gradually increases with the increase of temperature and finally gradually tends to a horizontal line, and the value is about 163 cal / cell.K.

[0102] As Figures 8(e) - 8(g) shown, then analyze the thermodynamic performance of β-phase silicon nitride, and analyze it respectively from aspects such as Debye temperature, entropy, enthalpy and heat capacity. When the pressure is 32 MPa, the Debye temperature of β-phase silicon nitride first decreases sharply with the increase of temperature. At 25 K, the Debye temperature is 1083 K, then it decreases, starts to rise at 45 K, and then slowly rises with the increase of temperature to 1209 K. Both entropy and enthalpy are positive values and increase with the increase of temperature, while the free energy is a negative value and decreases with the increase of temperature. The heat capacity gradually increases with the increase of temperature and finally gradually tends to a horizontal line, and the value is about 81 cal / cell.K.

[0103] As Figures 9(a) - 9(b) shown, mechanical performance analysis is respectively carried out on α-phase silicon nitride and β-phase silicon nitride after kinetic calculation, and the change of elastic constants is analyzed in this example.

[0104] With the increase of temperature and the occurrence of phase transformation, the elastic constants of α-phase silicon nitride and β-phase silicon nitride change accordingly. C 11 , C 22 and C 33 of α-phase silicon nitride all decrease with the increase of temperature, while C 11 , C 22 and C 33 of β-phase silicon nitride fluctuate greatly with the increase of temperature; C 44 , C 55 and C 66Both increase first and then decrease with the increase of temperature, while C of β-phase silicon nitride 44 , C 55 and C 66 do not change much with the increase of temperature.

[0105] According to the above thermodynamic performance analysis and kinetic performance analysis results, it can be found that: with the increase of pressure and temperature, silicon nitride will undergo a phase transition from α-phase to β-phase. The pressure and temperature of the phase transition are calculated by simulation. According to the basis that the Gibbs free energy G is equal when the phase transition of the two-phase material occurs, the intersection point is found, and the conditions at this point are the phase transition points.

[0106] Example Two

[0107] This example provides a performance simulation system based on the phase transition process of silicon nitride ceramics, including:

[0108] A monomer unit cell structure construction module, configured to: obtain the lattice information of silicon nitride in different phases, and respectively construct the monomer unit cell structures of silicon nitride in the corresponding phases;

[0109] A conformation optimization module, configured to: respectively perform conformation optimization on the monomer unit cell structures of all phases of silicon nitride under different pressure conditions;

[0110] A thermodynamic and kinetic calculation module, configured to: respectively perform thermodynamic calculations and kinetic calculations on all phases of silicon nitride after conformation optimization under different temperature conditions;

[0111] A ceramic sintering guidance module, configured to: respectively perform thermodynamic performance analysis and kinetic performance analysis on all phases of silicon nitride after kinetic calculation;

[0112] Based on the thermodynamic performance analysis and kinetic performance analysis results, determine the optimal sintering pressure and temperature for the phase transition of silicon nitride in different phases, providing a theoretical basis for guiding the sintering of ceramic materials.

[0113] Example Three

[0114] This example provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, it implements the steps of a performance simulation method based on the phase transition process of silicon nitride ceramics as described above.

[0115] Example Four

[0116] This example provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the steps in a performance simulation method based on the phase transition process of silicon nitride ceramics as described above.

[0117] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories and optical memories, etc.) that contain computer-usable program code.

[0118] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure One one flow or multiple flows and / or blocks Figure One one block or multiple blocks.

[0119] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing devices to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure One one flow or multiple flows and / or blocks Figure One one block or multiple blocks.

[0120] These computer program instructions can also be loaded onto a computer or other programmable data processing devices, such that a series of operation steps are performed on the computer or other programmable devices to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable devices provide steps for implementing the functions specified in Figure One one flow or multiple flows and / or blocks Figure One one block or multiple blocks.

[0121] Those of ordinary skill in the art can understand that to implement all or part of the processes in the above-described embodiment methods, it can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above-described method embodiments. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0122] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A performance simulation method based on the phase transition process of silicon nitride ceramics, characterized in that, It includes the following steps: Obtain the lattice information of different phases of silicon nitride, and respectively construct the monomer unit cell structures of the corresponding phases of silicon nitride; Under different pressure conditions, respectively perform conformational optimizations on all the monomer unit cell structures of silicon nitride phases; Based on all the silicon nitride phases after conformational optimization, perform thermodynamic calculations and kinetic calculations under different temperature conditions respectively; Perform thermodynamic property analysis and kinetic property analysis on all the silicon nitride phases after kinetic calculations respectively; Based on the results of thermodynamic property analysis and kinetic property analysis, determine the optimal sintering pressure and temperature for the phase transformation of different phases of silicon nitride, providing a theoretical basis for guiding the sintering of ceramic materials; Performing conformational optimizations on all the monomer unit cell structures of silicon nitride phases under different pressure conditions includes: Under different pressures, select simulation methods or software, set the precision, exchange-correlation functional, corresponding algorithms, Brillouin zone k-point sampling, and cut-off energy, and perform conformational optimizations on α-phase silicon nitride and β-phase silicon nitride respectively; The silicon nitride includes α-phase silicon nitride and β-phase silicon nitride; The thermodynamic property analysis includes: respectively analyze from the Debye temperature, entropy, enthalpy, and phonon spectrum curve to obtain the free energies of α-phase silicon nitride and β-phase silicon nitride, and fit the free energies at each pressure to obtain the pressure and temperature at the phase transition point; The kinetic property analysis includes: Analyze the mechanical properties of α-phase silicon nitride from the first temperature threshold to the phase transition point, and the mechanical properties of β-phase silicon nitride from the phase transition point to the second temperature threshold of 2073 K; The CASTEP module in Materials Studio is used for the thermodynamic calculations and kinetic calculations under different temperature conditions; The results of the thermodynamic property analysis and kinetic property analysis include: As the pressure and temperature increase, silicon nitride will undergo a phenomenon of transformation from the α-phase to the β-phase. Use simulation to calculate the pressure and temperature of the phase transition. According to the basis that the Gibbs free energy G is equal when the phase transition of the two-phase material occurs, find the intersection point, which is the phase transition point.

2. A performance simulation system based on the phase change process of silicon nitride ceramics, based on a performance simulation method for the phase change process of silicon nitride ceramics as described in claim 1, characterized in that, It includes: A monomer unit cell structure construction module, configured to: obtain the lattice information of different phases of silicon nitride, and respectively construct the monomer unit cell structures of the corresponding phases of silicon nitride; A conformational optimization module, configured to: under different pressure conditions, respectively perform conformational optimizations on all the monomer unit cell structures of silicon nitride phases; A thermodynamic and kinetic calculation module, configured to: based on all the silicon nitride phases after conformational optimization, perform thermodynamic calculations and kinetic calculations under different temperature conditions respectively; A ceramic sintering guidance module, configured to: perform thermodynamic property analysis and kinetic property analysis on all the silicon nitride phases after kinetic calculations respectively; Based on the results of thermodynamic property analysis and kinetic property analysis, determine the optimal sintering pressure and temperature for the phase transformation of different phases of silicon nitride, providing a theoretical basis for guiding the sintering of ceramic materials.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by a processor, it implements the steps in a performance simulation method based on the phase transformation process of silicon nitride ceramics as described in claim 1.

4. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in a performance simulation method based on the phase transformation process of silicon nitride ceramics as described in claim 1.

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