| It is of great significance to improve the accuracy of gun firing by mixing the rifling of winding degree.Magnetic field assisted electrochemical machining is an effective method to solve its machining problems.However,the way and mechanism of magnetic field's effect on machining accuracy and efficiency are still not clear,which limits the popularization and application of this technology to a certain extent.Therefore,this paper adopts molecular dynamics simulation method to study the influence of magnetic field on the micro-diffusion characteristics of electrolyte in electrochemical machining,so as to reveal the micro-behavior mechanism of magnetic field on electrolyte in electrochemical machining and provide theoretical basis for the technology of magnetic field-assisted electrochemical machining.In order to study the influence of magnetic field on the micro-diffusion characteristics and structure of electrolyte in electrochemical machining,the kinetic model of pure water under magnetic field was constructed,and the rigid SPCE water molecular model closest to the experimental data was selected.The simulation results show that the diffusion coefficient of water molecule decreases with the increase of magnetic field intensity.This is because the combination of external magnetic field and electric field makes many water molecules combine together through hydrogen bond to form different forms of water molecular chain or ring,thus forming a hydrogen bond grid formed by many water molecules,making the structure of water molecules more compact.Therefore,the diffusion coefficient of water molecules in pure water solution decreases with the increase of magnetic field intensity.Further,the mass fraction of 3.5%NaCl solution under the effect of magnetic field of microscopic diffusion characteristics are simulated,the simulation results,points out that in the solution of the diffusion coefficient of water molecules and ions are increased with the increase of magnetic field intensity.Contrary to the simulation results of the pure water solution,this is because in NaCl solution is the presence of sodium and chloride ions,it is under the effect of magnetic lorentz force,increases the probability of collision between ion and ion,ion around of the hydration number is reduced,and the interaction between water molecules is abate,reduce the number of hydrogen bonds formed between water molecules and the water molecules by a qualitative stability of damage,so the solution of the diffusion coefficient of water molecules with the strength of the magnetic field increases.In order to study the direction of the applied magnetic field and concentration of electrolyte electrolyte microscopic diffusion characteristics impact study,along the x,y,z three direction magnetic field and three kinds of concentration of water molecules in NaCl solution,sodium and chloride ion diffusion characteristics of the molecular dynamics simulation,the simulation results found that different concentration of electrolyte and magnetic field direction of the diffusion of water molecules and ions in the electrolyte present different effect.In order to verify the correctness of molecular simulation results,the infrared spectra of NaCl solution and pure water solution with a mass fraction of 24%under the action of magnetic field were tested.The results show that the strongest peaks of pure aqueous solution before and after magnetic field action are at 3354cm-1and the corresponding absorbance are 0.285 and 0.281,respectively.Before and after the magnetic field,the mass fraction of 24%NaCl solution is the highest peak at 3375cm-1,and the corresponding absorbances are 0.29 and 0.28 respectively.Based on the principle of solution infrared spectroscopy,the mass fraction before and after the magnetic field is calculated is 3.5%.The number of hydrated ions in the NaCl solution was 7.228 and 6.449,respectively;it was basically consistent with the simulation results,which verified the correctness of the molecular simulation model and process. |
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