| Surface micro-texture has shown great application value in many engineering projects,such as automobile,microelectronic chip and solar cells.Using electrolytic machining technology to produce fine pits and dents with a certain size and arrangement,on the surface of the workpiece,is called micro electrolytic machining technology.It is a hot research point in the projects of electrolytic machining technology.Because the influence of various physical and chemical fields involved in the micro electrolytic processing on workpiece is different from that of traditional electrochemical processing.When molding cathode is used to process microstructure,due to the small machining gap,the power supply is mostly pulse power supply,and the electrolyte flow mode is still liquid?or low flow rate?,so there is always electric double layer,concentration difference and gas not discharged from the processing area in the micro-electrolytic machining,et al.Accordingly,in order to obtain high-quality surface micro-texture,it is necessary to study various influencing factors.However,it is difficult to directly detect and analyze the current density,gas shape and double-layer voltage of each position in the processing system by means of detection in the actual processing process.In this paper,the main influencing factors such as double layer and gas-liquid two-phase flow in micro-texture processing are studied by computer simulation technology.?1?The Gouy-Chapman-Stern electric double layer physical model was used at the surface of the anode.When the ion concentration in the electrolyte is 1500 moles m-3,the double layer region near the anode is simulated under different applied potentials.The results show that the double layer voltage and the ion concentration on the surface of the double layer under different potential are better predicted.Secondly,When the double layer capacitance is 50?F·cm-2 and the electrolyte resistivity is 100?·mm,according to the mathematical expression,the relationship between of the electrode polarization potential,the electrolyte current density and the electric double layer charging time,the applied power pulse frequency,the machining gap and the like are simulated.Third,the influence of the double layer on the polarization of the electrodes was applied to the simulation of 2-D and 3-D micro-texture processing.The results predicted the etching of the anode boundary profile at different frequencies and the edge effect of the micro-texture in the steady-state electrical processing.?2?The electrochemical drilling experiment was carried out according to the"half-alignment"processing device of cathode and anode proposed in this paper.The formation of hydrogen bubbles on the cathode surface and oxygen bubbles on the anode surface were observed by high-speed photography.in the next place,observation of flow field in electrochemical micro-texture machining of stainless steel and conductive glass with a movable mask with a diameter of 200?m and a spacing of 700?m.Fluorescence microscopy was used to observe the process of gas nucleation,growth,coalescence and release from the front of array holes.?3?The relationship between gas-liquid two-phase flow and electric field in the electrolyte is couple simulated directly by finite element method.The results well show the dynamic process of the effect of gas-liquid two-phase flow on the electric field line during the release of hydrogen bubbles between 0 s and 0.22 s.The distance relationship between bubbles and boundary is quantitatively analyzed.The bear fruit show that the closer the bubble is to the anode boundary,the smaller the current density is.The bubble is farther and farther from the anode boundary and the current density is higher and higher.the effects of oxygen bubbles on the anode boundary current density in the micro-textured gap flow field were simulated when the inlet velocities of electrolyte were 0?m·s-1,400?m·s-1,800?m·s-1and 1200?m·s-1.In this paper,the related research on concentration,electric field and flow field is an extension of special micro machining technology,aiming to provide new analytical method and technical research methods,and applying it to the fabrication of micro-texture will play an important role in promoting the development of micro electrolytic machining. |
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