Method for obtaining hydrogen solubility in slag through molecular dynamics simulation

Abstract

The invention discloses a method for obtaining hydrogen solubility in slag based on microstructure analysis, and belongs to the field of high-temperature melt physical property characterization. The method comprises the following steps: determining initial components of a simulation system; establishing an initial structure model of the water molecule-containing slag system; determining a potential function for describing the simulation system; simulation calculation parameters are set, LAMMPS software is operated for simulation calculation, and simulation result data such as an atomic coordinate file and free energy of a simulation system are obtained; the atomic coordinate file is imported into visual software for statistical analysis and visual processing, and microstructure information of the slag is obtained; and calculating the hydrogen solubility of the slag according to simulation result data such as free energy. According to the method, the microstructure information of the atomic scale of the slag and the hydrogen solubility of the slag are calculated by adopting a molecular dynamics simulation method, so that the blank of experimental data can be filled, theoretical guidance is provided for controlling the hydrogen content of the slag, and a theoretical foundation is laid for controlling the hydrogen content of the molten steel.

Description

Technical Field

[0001] The invention relates to the field of high-temperature melt physical property characterization, and in particular to a method for obtaining hydrogen solubility of slag. Background Art

[0002] Hydrogen solubility is one of the important physical properties of slag, which reflects the ability of hydrogen to dissolve in slag under specific conditions. In the metallurgical process, the properties of slag have an important influence on the quality and production efficiency of metals. The solubility of hydrogen in slag is a key parameter, which is directly related to the hydrogen content in metal products, and thus affects the mechanical properties and corrosion resistance of metals. The traditional method of determining the hydrogen solubility of slag usually requires complex experiments, which is time-consuming and labor-intensive, and the experimental conditions are difficult to accurately control. In addition, due to the complexity of the slag system, there are often certain errors and uncertainties in the experimental results. Continuous casting is the last process of hydrogen-contaminated steel and the most likely link to increase hydrogen in the steelmaking process. Hydrogen in slag is the most important source of hydrogen in steel. In the continuous casting process, hydrogen is mainly transferred into steel through protective slag. The higher the hydrogen solubility in slag, the higher the hydrogen content in steel. Excessive hydrogen content can cause defects such as white spots, cracks, and bubbles in steel, leading to hydrogen embrittlement, stress corrosion, and hydrogen-induced fracture, and also reduce the yield strength, plasticity and other mechanical properties of steel. Therefore, accurately obtaining the solubility of hydrogen in the slag is of great significance for guiding the design and development of mold protection slag, optimizing the smelting process, improving steel quality, and improving production efficiency.

[0003] At present, hydrogen solubility is mainly obtained through experimental measurement methods, and commonly used methods include thermal analysis, electrochemical method and gas chromatography. There are many factors that affect the hydrogen solubility of slag, mainly including slag composition, temperature and pressure. For slag, the temperature is usually above 1800K. On the one hand, it is difficult to obtain stable high-temperature conditions, that is, it is difficult to accurately control the temperature, which affects the measurement accuracy of hydrogen solubility. On the other hand, high-temperature slag is very easy to react with the contact medium, that is, the slag composition is difficult to stably control, and the measured hydrogen solubility is easy to deviate from the true value; furthermore, the real slag components are complex, and the interactive effects of each component on hydrogen solubility are difficult to fully separate; in addition, the high-temperature determination of slag hydrogen solubility also has the disadvantages of complex process and high cost.

[0004] In recent years, with the rapid development of computer hardware and computer numerical simulation technology, molecular dynamics (MD) is a powerful method that uses Newton's laws of motion to simulate atomic or molecular systems. It can analyze physical and chemical processes at a microscopic scale. It has become an effective method for studying the microstructure and properties of materials, and its application in the field of high-temperature metallurgical melts is gradually expanding. Summary of the invention

[0005] (I) Purpose of the invention

[0006] In view of the shortcomings of the existing hydrogen solubility acquisition technology, the present invention provides a method for obtaining the hydrogen solubility of slag by simulation, that is, using the molecular dynamics simulation method to calculate the thermodynamic information and microstructural information of the slag, and on this basis obtain the hydrogen solubility of the slag under different composition conditions. This method can effectively avoid the problems of large data fluctuations, difficulty in separating influencing factors and high costs in traditional high-temperature experimental measurement methods; in addition, this method obtains hydrogen solubility based on the thermodynamic information and microstructural information of the slag, which can deepen the understanding of the essence of solubility and the analysis of influencing factors, and can provide clear guidance for the control of slag hydrogen solubility.

[0007] (II) Technical solution

[0008] In order to achieve the above object of the present invention, a method for obtaining hydrogen solubility based on microstructure analysis is provided, comprising the following steps:

[0009] S1. Determine the initial composition of the simulation system, calculate the content of each atom in the slag and the density of the slag, establish the initial structural model of the slag system containing water molecules, and determine the potential function and corresponding potential parameters that describe the interaction forces between all atoms contained in the simulation system;

[0010] S2, set simulation calculation parameters, write the in file required for executing the molecular dynamics simulation calculation of LAMMPS software, run the LAMMPS software for molecular dynamics simulation calculation, and obtain the simulation result data such as the atomic coordinate file and free energy of the simulation system;

[0011] S3. Import the atomic coordinate file obtained in S2 into a visualization analysis and processing software to obtain the microstructure information of the slag system and characterize the slag microstructure, and calculate the hydrogen solubility in the slag based on the simulation result data such as the free energy obtained in S2.

[0012] Furthermore, the initial components of the simulation system in step S1 include CaO, SiO 2、 Na2O, CaF2 and H2O.

[0013] Furthermore, the initial structural model of the slag system containing water molecules in step S1 is established in a cubic simulation box, the initial structural model of the slag system containing water molecules is established using Materials Studio software, and the initial structural model of the slag system containing water molecules is converted into a data file recognizable by LAMMPS software using visualization software OVITO.

[0014] Furthermore, the data file of the initial structural model of the slag system containing water molecules includes the number of atoms, the number of atomic types, the mass of each type of atoms, the atom ID and the atom type corresponding to the atom ID and the coordinate values ​​in the three directions of x, y and z.

[0015] Furthermore, the potential functions and corresponding potential parameters of all the interatomic interaction forces in step S1 are obtained through literature retrieval.

[0016] Furthermore, in the in file in step S2, simulation parameters required for calculating the slag microstructure and hydrogen solubility based on molecular dynamics simulation are set, and the simulation parameters include setting the system type, atom type, boundary conditions, ensemble, temperature control method, pressure control method and relaxation time.

[0017] Furthermore, the boundary conditions adopt periodic boundary conditions, the ensemble is an NVT canonical ensemble, the temperature control method is a Nose-Hoover heat bath method, and the pressure control method is a Parrinello-Rahman method.

[0018] Furthermore, the analysis and processing in step S3 uses software such as OVITO, VMD and ISAACS, and the microstructure information of the slag includes radial distribution function, coordination number, bond length between atomic pairs, trajectory graphic information of each atom and slag microstructure diagram.

[0019] Furthermore, the method for calculating the hydrogen solubility in the slag according to the simulation result data such as the free energy obtained in S2 in step S3 is as follows:

[0020] Based on the simulation results such as the free energy obtained in S2, the dissolution free energy, Henry's constant and fugacity are calculated:

[0021] ΔS=-RT(lne -ΔU ) (1)

[0022] Where △S represents the dissolution free energy in kJ / mol, R represents the ideal gas constant, T represents the temperature in K, and △U represents the free energy difference in kJ / mol;

[0023] k1=ρk B Te μΔS (2)

[0024] Where k1 represents Henry's constant, in Pa·m 3 / mol, ρ represents density, the unit is mol / m 3 , k B represents the Boltzmann constant, μ = 1 / (k B T);

[0025]

[0026] Where f1 represents the fugacity, the unit is Pa, P i θ Indicates the saturated vapor pressure of water, in Pa. Represents the fugacity coefficient, with the unit of 1, V i l Indicates molar volume, unit is m 3 / mol, P represents the system pressure, the unit is Pa;

[0027] Calculate the hydrogen solubility in slag:

[0028] x1=f1 / k1 (4)

[0029] Where x1 represents the mole fraction of hydrogen in the slag.

[0030] (III) Beneficial effects

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) Since the slag is under high-temperature melting conditions, it is difficult to directly study the thermodynamic information of the slag and the microstructure information at the atomic scale in experiments. Therefore, the present invention adopts the method of molecular dynamics simulation to calculate the thermodynamic information and the microstructure information of the slag at the atomic scale, and combines the visualization method to obtain the particle trajectory graphic information and the slag microstructure diagram that cannot be obtained in the experiment. The radial distribution function, bond length, coordination relationship and cluster of different atomic pairs (especially hydrogen and oxygen) in the slag are analyzed. The microstructure information of the slag under different composition conditions can be obtained, which is of great significance for the microstructure analysis of the slag.

[0033] (2) Based on the relationship between Henry's constant, fugacity and hydrogen solubility, the present invention provides a method for predicting and calculating the hydrogen solubility of slag from the atomic scale, which can obtain the hydrogen solubility of slag under different composition conditions, effectively avoid the problems of difficult separation of influencing factors, complex process and high cost in traditional high-temperature experimental determination, and can be used to fill the gaps in experimental data; combined with the microstructural information of the slag, the microstructural analysis of the hydrogen solubility of the slag can be performed, thereby providing theoretical guidance for the control of the hydrogen content in the slag, and further laying a theoretical foundation for the control of the hydrogen content in the molten steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention is described with the aid of the following drawings:

[0035] Figure 1 A flow chart of a method for obtaining hydrogen dissolution of slag by using molecular dynamics simulation according to the present invention;

[0036] Figure 2The atomic configuration diagram of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Example 1 of the present invention (CaF2 content is 20%);

[0037] Figure 3 A schematic diagram of the microstructure of the simulation system before and after data collection required for calculating hydrogen solubility in Example 1 of the present invention;

[0038] Figure 4 The calculation result of the radial distribution function of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Example 1 of the present invention;

[0039] Figure 5 The atomic configuration diagram of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Example 2 of the present invention (basicity is 2.5);

[0040] Figure 6 A schematic diagram of the microstructure of the simulation system before and after data collection required for calculating hydrogen solubility in Example 2 of the present invention;

[0041] Figure 7 The calculation result of the radial distribution function of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Example 2 of the present invention;

[0042] Figure 8 The atomic configuration diagram of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Example 3 of the present invention (Na2O content is 20%);

[0043] Fig. 9 A schematic diagram of the microstructure of the simulation system before and after data collection required for calculating hydrogen solubility in Example 3 of the present invention;

[0044] Fig.10 This is the calculation result of the radial distribution function of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Example 3 of the present invention. DETAILED DESCRIPTION

[0045] In order to better understand the technical solution of the present invention, the content of the present invention includes but is not limited to the specific implementation methods described below, and similar technologies and methods should be considered to be within the scope of protection of the present invention. In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0046] It should be clear that the embodiments described in the present invention are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "an" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0048] The present invention provides a method for calculating the hydrogen solubility of slag using molecular dynamics simulation. The flow chart of the method is as follows: Figure 1 As shown, the following steps are included:

[0049] S1. Determine the initial composition of the simulation system, calculate the content of each atom in the slag and the density of the slag, establish the initial structural model of the slag system containing water molecules, and determine the potential function and corresponding potential parameters that describe the interaction forces between all atoms contained in the simulation system;

[0050] S2, set simulation calculation parameters, write the in file required for executing the molecular dynamics simulation calculation of LAMMPS software, run the LAMMPS software for molecular dynamics simulation calculation, and obtain the simulation result data such as the atomic coordinate file and free energy of the simulation system;

[0051] S3. Import the atomic coordinate file obtained in S2 into a visualization analysis and processing software to obtain the microstructure information of the slag system and characterize the slag microstructure, and calculate the hydrogen solubility in the slag based on the simulation result data such as the free energy obtained in S2.

[0052] The method for calculating the hydrogen solubility in the slag according to the simulation result data such as the free energy obtained in S2 is as follows:

[0053] Based on the simulation results such as the free energy obtained in S2, the dissolution free energy, Henry's constant and fugacity are calculated:

[0054] ΔS=-RT(lne -ΔU ) (1)

[0055] Where △S represents the dissolution free energy in kJ / mol, R represents the ideal gas constant, T represents the temperature in K, and △U represents the free energy difference in kJ / mol;

[0056] k1=ρk B Te μΔS (2)

[0057] Where k1 represents Henry's constant, in Pa·m 3 / mol, ρ represents density, the unit is mol / m 3 , k B represents the Boltzmann constant, μ = 1 / (kB T);

[0058]

[0059] Where f1 represents the fugacity, the unit is Pa, P i θ Indicates the saturated vapor pressure of water, in Pa. Represents the fugacity coefficient, with the unit of 1, V i l Indicates molar volume, unit is m 3 / mol, P represents the system pressure, the unit is Pa;

[0060] Calculate the hydrogen solubility in slag:

[0061] x1=f1 / k1 (4)

[0062] Where x1 represents the mole fraction of hydrogen in the slag.

[0063] The simulation system in S1 consists of slag and water molecules. The initial structural model of the slag system containing water molecules is established in a cubic simulation box. The initial structural model of the slag system is established using Materials Studio software, and the visualization software OVITO is used to convert the initial structural model of the slag system containing water molecules into a data file recognizable by LAMMPS software.

[0064] In some examples, the data file of the initial structure model includes the number of atoms, the number of atomic types, the mass of each type of atoms, the atom ID and the atom type corresponding to the atom ID, and the coordinate values ​​in the three directions of x, y, and z.

[0065] The in file in S2 sets the simulation parameters required for calculating the slag microstructure and hydrogen solubility based on molecular dynamics simulation, and the simulation parameters include setting the system type, atom type, boundary conditions, ensemble, temperature control method, pressure control method and relaxation time.

[0066] In some examples, the atomic type is atomic, the boundary condition adopts a periodic boundary condition, the temperature control method is a Nose-Hoover heat bath method, and the pressure control method is a Parrinello-Rahman method.

[0067] The visualization analysis and processing in S3 uses software such as OVITO, VMD and ISAACS. The microstructure information of the slag includes the radial distribution function, coordination number, bond length between atomic pairs, trajectory graphic information of each atom and the slag microstructure diagram.

[0068] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0069] Example 1

[0070] In this embodiment, a method for obtaining hydrogen solubility in slag based on microstructure analysis of a CaO-SiO2-Na2O-CaF2-H2O quinary system is provided:

[0071] (1) According to the main chemical composition of metallurgical slag, the simulation system in this embodiment is composed of a CaO-SiO2-Na2O-CaF2-H2O quinary system, and the specific composition is CaO: 32.50%, SiO2: 32.50%, Na2O: 15.00%, CaF2: 20.00%.

[0072] (2) The number of atoms in the CaO-SiO2-Na2O-CaF2-H2O quinary system is set to 1118. The number of different atoms can be determined according to the molar ratio of each component in the CaO-SiO2-Na2O-CaF2-H2O quinary system. Then, the side length of the simulation box can be calculated according to the density of the CaO-SiO2-Na2O-CaF2-H2O quinary system under high temperature liquid conditions, as shown in Table 1.

[0073] Table 1 Atomic number, density and box side length of the CaO-SiO2-Na2O-CaF2-H2O quinary system

[0074]

[0075] Based on the atomic types, numbers and densities of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Table 1, the Materials Studio software was used to establish the initial structural model of the CaO-SiO2-Na2O-CaF2-H2O quinary system, and an initial structural data file containing the number of atoms, the number of atomic types, the mass of each type of atoms, the atomic ID and the atomic type corresponding to the atomic ID, and the coordinate values ​​in the x, y, and z directions was obtained.

[0076] (3) The Lennard-Jones potential (LJ potential) is selected as the potential function to describe the interaction forces between all atoms in the CaO-SiO2-Na2O-CaF2-H2O quinary system.

[0077] (4) Set the simulation parameters, write the in file required for executing the LAMMPS software molecular dynamics simulation calculation, and import the initial structure model information of the CaO-SiO2-Na2O-CaF2-H2O quinary system into the LAMMPS software for molecular dynamics simulation calculation. The atom type is set to atomic, and the periodic boundary conditions are used. The canonical ensemble (NVT) is used throughout the simulation process. The number of atoms, volume and temperature remain unchanged during the simulation. The Parrinello-Rahman method and the Nose-Hoover heat bath method are used to control the pressure and temperature. The initial velocity distribution of hydrogen atoms is given according to the Gaussian velocity distribution. The numerical solution of the Newtonian motion equation of the system is solved by the Verlet algorithm, the step size is set to 0.001ps, and a total of 1,350,000 steps are run. First, the conjugate gradient method is used to minimize the energy of the initial structure, and 400,000 steps are run at an initial temperature of 3000K to ensure that the system is fully mixed and energy stable. Next, run 250,000 steps to cool the system to 1823K, and continue to relax at 1823K for 500,000 steps. Then, use the NVE ensemble to run 100,000 steps. During the simulation, the number of atoms, volume, and energy remain unchanged to observe whether the system is stable. After confirming that the system is stable, run 100,000 steps to collect the data required for calculating microstructure information and hydrogen solubility, and finally obtain the atomic coordinate file, free energy and other simulation result data of the simulation system.

[0078] (5) The obtained atomic coordinate file was imported into OVITO, VMD and ISAACS software for visualization analysis and calculation of the microstructure information of the simulation system to obtain the microstructure diagram of the simulation system; the atomic configuration diagram of the CaO-SiO2-Na2O-CaF2-H2O quinary system before simulation is shown in Figure 2 The microstructure diagram of the simulation system before and after the data collection required for calculating hydrogen solubility is shown in Figure 3 As shown. Different types of atoms are distinguished, and the radial distribution function between different atomic pairs is calculated; the bond length (nearest neighbor distance) between different atomic pairs is obtained based on the calculated horizontal coordinate value of the first peak of the radial distribution function, and the coordination number between different atomic pairs can be obtained by integrating the first peak of the radial function. The atomic coordinate files of different areas of the simulation box can be exported for microstructure information calculation. The radial distribution function of the CaO-SiO2-Na2O-CaF2-H2O quinary system in this embodiment is as follows Figure 4 As shown, the average bond lengths of Ca-O, Ca-Si, FO, HO, Na-O, OO, and Si-O atomic pairs are If the distance between atoms is less than the corresponding bond length value, it means that the two atoms are connected to each other. According to the number of oxygen atoms connected to the hydrogen atom, the hydrogen atom can be divided into three categories: free hydrogen atoms (no coordination relationship with oxygen atoms), type A hydrogen (only forms a coordination relationship with 1 oxygen atom), and type B hydrogen (forms a coordination relationship with 2 or more oxygen atoms). The coordination mode of hydrogen atoms can be analyzed based on the simulation result data.

[0079] (6) Based on the collected data required for calculating hydrogen solubility, the hydrogen solubility of the CaO-SiO2-Na2O-CaF2-H2O quinary system (CaF2 content is 20%) is calculated using the calculation method of slag hydrogen solubility of the invention. The mole fraction of hydrogen in the CaO-SiO2-Na2O-CaF2-H2O quinary system calculated in this embodiment is calculated to be 46.83. The calculation results of Example 1 are shown in Table 2.

[0080] Table 2 Calculation results of Example 1

[0081]

[0082] Example 2

[0083] In this embodiment, a method for obtaining hydrogen solubility in slag based on microstructure analysis of a CaO-SiO2-Na2O-CaF2-H2O quinary system is provided:

[0084] (1) According to the main chemical composition of metallurgical slag, the simulation system in this embodiment is composed of a CaO-SiO2-Na2O-CaF2-H2O quinary system, and the specific composition is CaO: 53.57%, SiO2: 21.43%, Na2O: 15.00%, CaF2: 10.00%.

[0085] (2) The number of atoms in the CaO-SiO2-Na2O-CaF2-H2O quinary system is set to 1160. The number of different atoms can be determined based on the molar ratio of each component in the CaO-SiO2-Na2O-CaF2-H2O quinary system. Then, the side length of the simulation box can be calculated based on the density of the CaO-SiO2-Na2O-CaF2-H2O quinary system under high temperature liquid conditions, as shown in Table 3.

[0086] Table 3 Number of atoms, density and box side length of the CaO-SiO2-Na2O-CaF2-H2O quinary system

[0087]

[0088] Based on the atomic types, numbers and densities of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Table 3, the Materials Studio software was used to establish the initial structural model of the CaO-SiO2-Na2O-CaF2-H2O quinary system, and an initial structural data file containing the number of atoms, the number of atomic types, the mass of each type of atoms, the atomic ID and the atomic type corresponding to the atomic ID, and the coordinate values ​​in the x, y, and z directions was obtained.

[0089] (3) The Lennard-Jones potential (LJ potential) is selected as the potential function to describe the interaction forces between all atoms in the CaO-SiO2-Na2O-CaF2-H2O quinary system.

[0090] (4) Set the simulation parameters, write the in file required for executing the LAMMPS software molecular dynamics simulation calculation, and import the initial structure model information of the CaO-SiO2-Na2O-CaF2-H2O quinary system into the LAMMPS software for molecular dynamics simulation calculation. The atom type is set to atomic, and the periodic boundary conditions are used. The canonical ensemble (NVT) is used throughout the simulation process. The number of atoms, volume and temperature remain unchanged during the simulation. The Parrinello-Rahman method and the Nose-Hoover heat bath method are used to control the pressure and temperature. The initial velocity distribution of hydrogen atoms is given according to the Gaussian velocity distribution. The numerical solution of the Newtonian motion equation of the system is solved by the Verlet algorithm, the step size is set to 0.001ps, and a total of 1,350,000 steps are run. First, the conjugate gradient method is used to minimize the energy of the initial structure, and 400,000 steps are run at an initial temperature of 3000K to ensure that the system is fully mixed and energy stable. Next, run 250,000 steps to cool the system to 1823K, and continue to relax at 1823K for 500,000 steps. Then, use the NVE ensemble to run 100,000 steps. During the simulation, the number of atoms, volume, and energy remain unchanged to observe whether the system is stable. After confirming that the system is stable, run 100,000 steps to collect the data required for calculating microstructure information and hydrogen solubility, and finally obtain the atomic coordinate file, free energy and other simulation result data of the simulation system.

[0091] (5) The obtained atomic coordinate file was imported into OVITO, VMD and ISAACS software for visualization analysis and calculation of the microstructure information of the simulation system to obtain the microstructure diagram of the simulation system; the atomic configuration diagram of the CaO-SiO2-Na2O-CaF2-H2O quinary system before simulation is shown in Figure 5 The microstructure diagram of the simulation system before and after the data collection required for calculating hydrogen solubility is shown in Figure 6As shown. Different types of atoms are distinguished, and the radial distribution function between different atomic pairs is calculated; the bond length (nearest neighbor distance) between different atomic pairs is obtained based on the calculated horizontal coordinate value of the first peak of the radial distribution function, and the coordination number between different atomic pairs can be obtained by integrating the first peak of the radial function. The atomic coordinate files of different areas of the simulation box can be exported for microstructure information calculation. The radial distribution function of the CaO-SiO2-Na2O-CaF2-H2O quinary system in this embodiment is as follows Figure 7 As shown, the average bond lengths of Ca-O, Ca-Si, FO, HO, Na-O, OO, and Si-O atomic pairs are If the distance between atoms is less than the corresponding bond length value, it means that the two atoms are connected to each other. According to the number of oxygen atoms connected to the hydrogen atom, the hydrogen atom can be divided into three categories: free hydrogen atoms (no coordination relationship with oxygen atoms), type A hydrogen (only forms a coordination relationship with 1 oxygen atom), and type B hydrogen (forms a coordination relationship with 2 or more oxygen atoms). The coordination mode of hydrogen atoms can be analyzed based on the simulation result data.

[0092] (6) Based on the collected data required for calculating hydrogen solubility, the hydrogen solubility of the CaO-SiO2-Na2O-CaF2-H2O quinary system (basicity is 2.5) is calculated using the inventive method for calculating slag hydrogen solubility. The molar fraction of hydrogen in the CaO-SiO2-Na2O-CaF2-H2O quinary system calculated in this embodiment is calculated to be 9.36. The calculation results of Example 2 are shown in Table 4.

[0093] Table 4 Calculation results of Example 2

[0094]

[0095] Example 3

[0096] In this embodiment, a method for obtaining hydrogen solubility in slag based on microstructure analysis of a CaO-SiO2-Na2O-CaF2-H2O quinary system is provided:

[0097] (1) According to the main chemical composition of metallurgical slag, the simulation system in this embodiment is composed of a CaO-SiO2-Na2O-CaF2-H2O quinary system, and the specific composition is CaO: 35.00%, SiO2: 35.00%, Na2O: 20.00%, CaF2: 10.00%.

[0098] (2) The number of atoms in the CaO-SiO2-Na2O-CaF2-H2O quinary system is set to 1136. The number of different atoms can be determined according to the molar ratio of each component in the CaO-SiO2-Na2O-CaF2-H2O quinary system. Then, the side length of the simulation box can be calculated according to the density of the CaO-SiO2-Na2O-CaF2-H2O quinary system under high temperature liquid conditions, as shown in Table 5.

[0099] Table 5 Atomic number, density and box side length of the CaO-SiO2-Na2O-CaF2-H2O quinary system

[0100]

[0101] Based on the atomic types, numbers and densities of the CaO-SiO2-Na2O-CaF2-H2O quinary system in Table 5, the Materials Studio software was used to establish the initial structural model of the CaO-SiO2-Na2O-CaF2-H2O quinary system, and an initial structural data file containing the number of atoms, the number of atomic types, the mass of each type of atoms, the atomic ID and the atomic type corresponding to the atomic ID, and the coordinate values ​​in the x, y, and z directions was obtained.

[0102] (3) The Lennard-Jones potential (LJ potential) is selected as the potential function to describe the interaction forces between all atoms in the CaO-SiO2-Na2O-CaF2-H2O quinary system.

[0103] (4) Set the simulation parameters, write the in file required for executing the LAMMPS software molecular dynamics simulation calculation, and import the initial structure model information of the CaO-SiO2-Na2O-CaF2-H2O quinary system into the LAMMPS software for molecular dynamics simulation calculation. The atom type is set to atomic, and the periodic boundary conditions are used. The canonical ensemble (NVT) is used throughout the simulation process. The number of atoms, volume and temperature remain unchanged during the simulation. The Parrinello-Rahman method and the Nose-Hoover heat bath method are used to control the pressure and temperature. The initial velocity distribution of hydrogen atoms is given according to the Gaussian velocity distribution. The numerical solution of the Newtonian motion equation of the system is solved by the Verlet algorithm, the step size is set to 0.001ps, and a total of 1,350,000 steps are run. First, the conjugate gradient method is used to minimize the energy of the initial structure, and 400,000 steps are run at an initial temperature of 3000K to ensure that the system is fully mixed and energy stable. Next, run 250,000 steps to cool the system to 1823K, and continue to relax at 1823K for 500,000 steps. Then, use the NVE ensemble to run 100,000 steps. During the simulation, the number of atoms, volume, and energy remain unchanged to observe whether the system is stable. After confirming that the system is stable, run 100,000 steps to collect the data required for calculating microstructure information and hydrogen solubility, and finally obtain the atomic coordinate file, free energy and other simulation result data of the simulation system.

[0104] (5) The obtained atomic coordinate file was imported into OVITO, VMD and ISAACS software for visualization analysis and calculation of the microstructure information of the simulation system to obtain the microstructure diagram of the simulation system; the atomic configuration diagram of the CaO-SiO2-Na2O-CaF2-H2O quinary system before simulation is shown in Figure 8 The microstructure diagram of the simulation system before and after the data collection required for calculating hydrogen solubility is shown in Fig. 9 As shown. Different types of atoms are distinguished, and the radial distribution function between different atomic pairs is calculated; the bond length (nearest neighbor distance) between different atomic pairs is obtained based on the calculated horizontal coordinate value of the first peak of the radial distribution function, and the coordination number between different atomic pairs can be obtained by integrating the first peak of the radial function. The atomic coordinate files of different areas of the simulation box can be exported for microstructure information calculation. The radial distribution function of the CaO-SiO2-Na2O-CaF2-H2O quinary system in this embodiment is as follows Fig.10 As shown, the average bond lengths of Ca-O, Ca-Si, FO, HO, Na-O, OO, and Si-O atomic pairs are If the distance between atoms is less than the corresponding bond length value, it means that the two atoms are connected to each other. According to the number of oxygen atoms connected to the hydrogen atom, the hydrogen atom can be divided into three categories: free hydrogen atoms (no coordination relationship with oxygen atoms), type A hydrogen (only forms a coordination relationship with 1 oxygen atom), and type B hydrogen (forms a coordination relationship with 2 or more oxygen atoms). The coordination mode of hydrogen atoms can be analyzed based on the simulation result data.

[0105] (6) Based on the collected data required for calculating hydrogen solubility, the hydrogen solubility of the CaO-SiO2-Na2O-CaF2-H2O quinary system (Na2O content is 20%) is calculated using the inventive method for calculating slag hydrogen solubility. The molar fraction of hydrogen in the CaO-SiO2-Na2O-CaF2-H2O quinary system calculated in this embodiment is calculated to be 0.035. The calculation results of Example 3 are shown in Table 6.

[0106] Table 6 Calculation results of Example 3

[0107]

[0108] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not depart from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for obtaining hydrogen solubility in slag using molecular dynamics simulation, characterized in that: The following steps are involved: S1. Determine the initial composition of the simulation system, calculate the content of each atom in the slag and the density of the slag, establish the initial structural model of the slag system containing water molecules, and determine the potential function and corresponding potential parameters that describe the interaction forces between all atoms contained in the simulation system; S2, set simulation calculation parameters, write the in file required for executing the molecular dynamics simulation calculation of LAMMPS software, run the LAMMPS software for molecular dynamics simulation calculation, and obtain the simulation result data such as the atomic coordinate file and free energy of the simulation system; S3. Import the atomic coordinate file obtained in S2 into a visualization analysis and processing software to obtain the microstructure information of the slag system and characterize the slag microstructure, and calculate the hydrogen solubility in the slag based on the simulation result data such as the free energy obtained in S2.

2. The method for obtaining hydrogen solubility in slag by molecular dynamics simulation according to claim 1, characterized in that: The initial components of the simulation system in S1 include CaO, SiO 2、 Na2O, CaF2 and H2O.

3. The method for obtaining hydrogen solubility in slag by molecular dynamics simulation according to claim 1, characterized in that: The initial structural model of the slag system containing water molecules in S1 is established in a cubic simulation box, and the initial structural model of the slag system containing water molecules is established using MaterialsStudio software, and the visualization software OVITO is used to convert the initial structural model of the slag system containing water molecules into a data file recognizable by LAMMPS software.

4. The method for obtaining hydrogen solubility in slag by molecular dynamics simulation according to claim 3, characterized in that: The data file of the initial structure model includes the number of atoms, the number of atomic types, the mass of each type of atoms, the atom ID and the atom type corresponding to the atom ID, and the coordinate values ​​in the x, y, and z directions.

5. The method for obtaining hydrogen solubility in slag by molecular dynamics simulation according to claim 1, characterized in that: The potential functions and corresponding potential parameters of all interatomic interaction forces in S1 were obtained through literature retrieval.

6. The method for obtaining hydrogen solubility in slag by molecular dynamics simulation according to claim 1, characterized in that: The in file in S2 sets the simulation parameters required for calculating the slag microstructure and hydrogen solubility based on molecular dynamics simulation, and the simulation parameters include setting the system type, atom type, boundary conditions, ensemble, temperature control method, pressure control method and relaxation time.

7. The method for obtaining hydrogen solubility in slag by molecular dynamics simulation according to claim 1, characterized in that: The analysis and processing in S3 uses software such as OVITO, VMD and ISAACS. The microstructure information of the slag includes the radial distribution function, coordination number, bond length between atomic pairs, trajectory graphic information of each atom and the slag microstructure diagram.

8. The method for obtaining hydrogen solubility in slag by molecular dynamics simulation according to claim 1, characterized in that: The method for calculating the hydrogen solubility in the slag according to the simulation result data such as the free energy obtained in S2 in S3 is as follows: Based on the simulation results such as the free energy obtained in S2, the dissolution free energy, Henry's constant and fugacity are calculated: ΔS=-RT(lne -ΔU ) (1) Where △S represents the dissolution free energy in kJ / mol, R represents the ideal gas constant, T represents the temperature in K, and △U represents the free energy difference in kJ / mol; k1=ρk B The μΔS (2) Where k1 represents Henry's constant, in Pa·m 3 / mol, ρ represents density, the unit is mol / m 3 , k B represents the Boltzmann constant, μ = 1 / (k B T); Where f1 represents the fugacity, the unit is Pa, P i θ Indicates the saturated vapor pressure of water, in Pa. Represents the fugacity coefficient, with the unit of 1, V i l Indicates molar volume, unit is m 3 / mol, P represents the system pressure, the unit is Pa; Calculate the hydrogen solubility in slag: x1=f1 / k1 (4) Where x1 represents the mole fraction of hydrogen in the slag.

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