High Efficiency Machining Of Microelectrode With Large Aspect Ratio By Microelectrochemistry Based On Critical Gap

With the rapid development of precision and miniaturization of products,microstructures are widely used in the fields of MEMS,aerospace,electronic communication,micro machinery and micro mold.As the basic unit of microstructure manufacturing,micro-tool electrode has been a key issue and frontier hotspot in the field of microfabrication with its efficient and controllable processing technology.This paper proposes a method for high-efficiency machining of micro-tool electrodes based on the critical gap.It uses Na OH alkaline electrolyte and microsecond power supply to realize the micron-level precision controllable removal of tungsten electrodes by adjusting the machining gap.The problem of long preparation time and complicated process of the micro-tool electrode is solved,which is expected to be applied to actual production.The main research contents of this topic are as follows:（1）By analyzing the change of gap current density under the condition of gap change,the selection range of parameters for controlling material removal based on the critical gap is determined,the mathematical model of the erosion process of the micro tool electrode material is obtained,and the change law of the material erosion amount at different times is obtained.The correctness of the mathematical model is further proved by the experiments of machining at different times.（2）The process experiment research of the method of preparing micro tool electrode by micro electrochemistry based on the critical gap was carried out.A metal tungsten wire with a diameter of 300μm is used as the anode workpiece,and a 0.5mol/L sodium hydroxide alkaline solution is selected as the electrochemical removal processing electrolyte.The influences of various process parameters,such as machining voltage,electrolyte concentration,pulse period and pulse width,on the critical reaction distance and its error as well as the removal rate of micro-tool electrode materials were studied.（3）By precisely controlling the machining gap between the two poles,a fine tool electrode with the designed diameter can be obtained.Using the method of critical gap,the micro-tool electrode with a diameter of 10μm and a aspect ratio of 200:1 was successfully fabricated by taking the processing voltage of 6V,the concentration of electrolyte of 0.5mol/L,the pulse period of 500μs and the pulse width of 250μs,the material removal rate can reach up to 2.7×10^-2mm³/min,and the processing efficiency can reach ten times that of the current commonly used preparation methods for micro-tool electrodes.（4）In order to verify the usability of the prepared microelectrodes,in a weakly acidic environment,a current density model based on the critical gap in micro-slit processing was established,and the selection range of processing parameters was obtained.At the same time,a micro-slit electrochemical cutting process experiment based on the critical gap was carried out.Under the processing conditions of a voltage of 4V,an electrolyte concentration of 0.1mol/L,a pulse period of 10μs,and a pulse width of 4μs,a micro tool electrode with a diameter of 30μm was successfully prepared.The"W"-shaped micro-slit structure with a side gap of 18.75μm proves the method’s ability to control the side gap of the micro-slit in complex trajectory processing.