Investigation On Electrochemical Deposition Technology Based On Liquid Confinement

Based on the principle of layered manufacturing,additive manufacturing technology breaks through the limitations of traditional part forming and processing,and can directly manufacture complex three-dimensional structures that cannot be achieved by traditional processing technology.Electrochemical deposition processing technology is a micro-additive manufacturing technology that manufactures metal-based parts in an atomic-level layer-by-layer stacking method.It has a wide range of applicable materials,low implementation temperature(generally below 70°C),flexible application form,and easy controllability.Control shape,not limited by size and so on.Compared with other metal additive manufacturing technologies,such as laser additive manufacturing,electron beam additive manufacturing and arc additive manufacturing,it does not require subsequent annealing and homogenization heat treatment,and has no residual stress,so it is very suitable for the manufacture of complex micro-metal structures.However,the current electrochemical deposition method still has certain limitations,such as the poor flexibility of mask deposition,the need for many high-precision masks in the processing process,and the complex processing technology;maskless deposition has low processing precision,poor processing localization,Problems such as slow processing speed.In this thesis,a new method of electrochemical deposition based on liquid confinement is proposed,which utilizes the characteristics of high density,water insolubility and high resistivity of methylene chloride to confine the electroforming liquid in a tiny area(deposition zone)under the nozzle,thereby The stray deposition caused by the spreading of the electroforming solution on the surface of the substrate is avoided,and the localization of the microstructure deposition is improved.Moreover,with the change of the nozzle movement trajectory,the deposition area will always be constrained by dichloromethane,so that localized deposition of microstructures with different shapes can be achieved.The main research contents of this thesis are as follows:(1)A liquid-confined electrochemical deposition method is proposed,which utilizes the high density of methylene chloride(1.325 g/cm~2),slightly soluble in water(solubility at25°C is less than 1%),and electrical insulation(resistivity of 2.3×10¹⁰?·m),which was chosen as the confinement liquid.A liquid confinement electrochemical deposition test platform was built,and the design and development of the motion control system,online observation system and electrochemical deposition system were completed.(2)A two-phase flow simulation model of the liquid-confined electrochemical deposition method was established,and the flow pattern of the electroforming liquid under the confinement of dichloromethane was simulated and analyzed.The simulation results were compared with the actual observations,and the flow characteristics were explored and studied.The effect of different machining gaps on the flow range of electroforming fluids was investigated.Based on the fluid simulation analysis,an electric field simulation model was established to study the influence of different machining gaps on the current density distribution on the cathode substrate.(3)The experimental study of dichloromethane confinement electrochemical deposition was carried out,and the microstructure size and outline of the deposition without liquid confinement and liquid confinement were compared,which showed that the process localization of electrodeposition was significantly improved under dichloromethane confinement.The effects of key process parameters such as initial machining gap,machining current and nozzle moving speed on current efficiency and machining surface quality were explored.Under the optimal parameters of machining gap of 100?m,current of 0.0015 A,and nozzle reciprocating speed of 300?m/s,linear microstructures with high surface quality and good size consistency were deposited,showing the flexibility of liquid-confined electrochemical deposition method.and high locality.