Research On One-Step Forming Printing Technology Of Electrohydrodynamics

Micro-scale 3D printing technology based on electrohydrodynamics(EHD)(current body power printing or electro-jet printing)is a new micro-nano scale 3D printing technology that has emerged in recent years.The basic structure is simple,the printing resolution is high,and the applicable materials are extremely wide,and a high viscosity solution can be printed.Generally,the electrohydrodynamic printing needs to cure the solution printed on the substrate by additional sintering means such as hot pressing sintering,laser sintering,etc.after printing,and the one-step forming electrohydrodynamic printing produces Joule through the printing solution itself.The sintering process is completed by heat,which simplifies the sintering process and improves the printing efficiency and resolution of electrohydrodynamic printing.This paper firstly combines the basic theoretical knowledge of electrodynamics and fluid mechanics to systematically expound the theory of electrohydrodynamic printing,and theoretically analyzes the situation of two different conductive properties of conductors and dielectrics as electrohydrodynamic printing materials.The general print mode and voltage control mode of electrohydrodynamic printing are summarized.The theoretical stress analysis of the Taylor cone which is the steady state of jet flow during electrohydrodynamic printing is carried out,and the effects of solution dynamic viscosity,surface tension and electric field force on Taylor cone state are summarized.We made Multi-physics model to simulate the formation of cone jet,and we studyed the influents of process characteristics(voltage,inlet pressure)and material properties(surface tension of solution,viscosity of solution,Newtonian and non-Newtonian solution,the height of nozzle,the wettability of nozzle)on shape of Talor cone.Resuls is basically consistent with the theoretical analysis.The theoretical analysis of one-step forming electrohydrodynamic printing and sintering process is carried out.According to the objective facts that the melting point of nanoparticles is low and the nanoparticles carry a large amount of electric charge,the speculation of Joule heat self-sintering is proposed.Combined with the experimental data in the relevant literature,the Joule thermal modeling simulation of the one-step electrokinetic printing of polymer Ag nanoparticle solution was carried out.The simulation results show that:1.When a voltage of 1.8kv is applied and the height of the sintered cylinder is 30 um,the contact area of the Ag nanoparticle and the sintered cylinder is 0.1nm,the contact temperature is as high as 808?,and it is enough to Ag with a melting point of about 150?.The nanoparticles melt.As the thickness of the contact area between the nanoparticles and the sintered cylinder increases,the sintering temperature begins to decrease,and the sintering of the nanoparticles is completed when the melting point is reached.2.When the thickness of the bonded area of the nanoparticle and the column is constant and the height of the sintered cylinder is the same,the higher the voltage,the higher the sintering temperature;the sintered cylinder is increased and the sintering temperature is increased;3.For different nanoparticles,the higher the conductivity,the greater the contact resistance,and the higher the sintering temperature,the higher the sintering temperature of silver,copper,gold and aluminum nanoparticles.