Study On Interface Reaction Mechanism Of Electrolytic Plasma Polishing For Stainless Steel

Aerospace,biomedicine,nuclear industry,ocean engineering,and other high-end equipment manufacturing fields have emerged continuously irregular shapes of complex curved parts,the requirements for surface quality and performance are increasingly strict.Conventional surface polishing techniques,including mechanical polishing,electrochemical polishing,energy beam polishing,and other techniques have various problems.In recent years,electrolytic plasma polishing technology has attracted wide attention due to its advantages of shape adaptability,high efficiency,high precision,environmental friendliness,and noncontact polishing.However,the related mechanism and model of electrolytic plasma polishing,the process parameter law,and the influence mechanism on the workpiece surface properties have not been studied sufficiently,which restricts its application in practical production.Therefore,the interface reaction mechanism of stainless steel during the electrolytic plasma polishing process was studied by combining theoretical analysis,experimental research,and material characterization.The material removal mechanism of the plasma electrochemical reaction based on the gas layer discharge has been proposed,and the dynamic model of the interfacial reaction has been established.On this basis,the influence law of key parameters on the polishing has been studied,and the influence mechanism of the interfacial reaction on the surface properties of stainless steel has been clarified,which provides a certain reference for the further development and application of electrolytic plasma polishing technology.The main research contents are as follows:On the basis of the evolution process and discharge of the gas layer,the mechanism of gas layer to interface reaction was studied.The thermodynamic conditions of gas layer generation during the electrolytic plasma polishing process of stainless steel were explored by theoretical analysis and experimental research,and the influence law of voltage and electrolyte temperature on the dynamic evolution of gas layer was revealed.The effect and influence of the gas discharge on the generation of strong oxidizing radicals and reactive substances in the polishing process were studied by analyzing the theoretical of gas breakdown discharge.The auxiliary enhancement effect of gas discharge on the interface reaction and the promotion effect of gas evolution on the rapid diffusion of products on the anode surface were revealed.The mechanism of the interfacial plasma electrochemical reaction was revealed by drawing on the principle of electrochemical reaction and discharge plasma theory.The composition of the stainless steel surface passivation layer and the characteristics of the interfacial plasma electrochemical reaction were analyzed using electrochemical property testing methods.The interfacial plasma electrochemical reaction was proposed to be divided into plasma oxidation reaction and plasma dissolution reaction.Based on experimental research and material test characterization,it was proposed that the main material removal methods for electrolytic plasma polishing are the interfacial plasma oxidation reaction and plasma dissolution reaction with the action of gas layer discharge.Based on theoretical analysis,model establishment,and experimental study,it was revealed that the solution rate of the passivation layer in the bulge is higher than that in the sag,which is the main mechanism of microleveling of electrolytic plasma polishing for stainless steel.The physical model of the double electric layer of the interface was established by improving the Gouty-Chapman-Stern model,which includes both the dense layer and the diffusion layer.The kinetic model of the interface reaction was established by combining the Butler-Volmer formula.The main factors that affect the reaction rate of electrode are voltage,electrolyte concentration,and electrolyte temperature by analyzing the key factors affecting the kinetic behavior.Through calculation of kinetic parameters,model verification,and theoretical analysis,the influence mechanism of the electrolyte temperature and electrolyte concentration on the interface reaction rate of electrolytic plasma polishing stainless steel was revealed.On the basis of the interface reaction mechanism and kinetic model,the influence mechanism of key parameters on stainless steel electrolyte plasma polishing was studied with surface roughness and material removal rate as evaluation indexes.The influence laws of voltage,electrolyte temperature,electrolyte concentration,and processing time on surface roughness and material removal rate were revealed by single factor experiments,and the validity of the kinetic model was verified.The composite influence law of voltage,electrolyte temperature,and electrolyte concentration on the polishing effect was revealed by the response surface test method.It was concluded that when the voltage was 238 V,the temperature was72 ℃ and the electrolyte concentration was 3.8 wt%,the lowest roughness and the highest material removal rate could be achieved simultaneously.The optimized parameters of the stainless steel parts with irregular curved surfaces were tested and verified.The average surface roughness Ra decreased from 0.73 μm to 0.078 μm after polishing,which providing a reference for the industrial application of electrolytic plasma polishing stainless steel.The influence of the interface reaction mechanism on the microstructure and properties of electrolytic plasma polished stainless steel surface was revealed by theoretical analysis and material characterization,and the mechanism of the interface reaction was verified.Microstructure,mechanical properties,wettability,and corrosion resistance were characterized by XRD,electron backscatter diffraction,field emission transmission electron microscopy,Xray residual stress analyzer,and electronic tensile testing machine.It is proposed that the dynamic complex energy field of the interfacial plasma electrochemical reaction,high-energy plasma bombardment,and annealing stress in the material leads to microstructure evolution,the improvement of yield strength and tensile strength,and the hydrophobic property of stainless steel.In addition,the passivation film generated by the interface reaction and the transformation of the microstructure are the mechanism of corrosion resistance enhancement,providing a new idea and method for the surface processing and corrosion prevention of stainless steel.