| Jet electrodeposition is a kind of high-speed electrodeposition technology without mask that performs selective electrodeposition on a cathode substrate.It has a good application prospect in the field of 3D micro-additive manufacturing because of its fast deposition rate,good selectivity(high localization)and high degree of freedom.To meet the increasingly needs of applications,it is becoming a hot topic and frontier research in the field of 3D metal additive manufacturing to explore high-efficiency additive manufacturing of three-dimensional(3D)metal microstructures and parts.Although jet electrodeposition holds potential advantages in the manufacturing of micro,nano-scale3 D components and structure,the core problem of preparing high-quality jet has not yet been solved,so this technology has been virtually impossible to use for engineered additive manufacturing of 3D metal microstructures and parts.Therefore,it is top priority to develop advanced 3D metal micro-additive manufacturing technology.Our group found that based on the unique working mechanism,Flow Focusing technology can break through limit of the traditional method of jet preparation,which provides support for preparing high-quality jet(long range,large jet velocity,small beam,high uniform flow field,strong localization etc.).Therefore,this study integrates the Flow Focusing into the Jet Electrochemical deposition to replace the conventional open jet(single electrolyte)with the high-quality micro-jet(the outer layer is electrical insulation high-speed fluid and the kernel is the electrolyte),forming a new Jet Electrochemical deposition technology-Focused Jet 3D-electrodeposition technology.This work was financially supported by the National Natural Science Foundation of China(No.51475149),Program for Science & Technology Innovation Team in Universities of Henan Province(No.15IRTSTHN013),Program for Science&Technology Innovation Team in Henan Polytechnic University(No.T2014-1).Details are as follows:(1)The relationship between the structural parameters of the focusing device,the focused jet condition parameters and the focused jet free jet region flow field distribution was investigated and the effects of focused device structure parameters and focused jet fluid dynamics parameters on focused jet flow field distributioncharacteristics was analysed.The results show that: Compared to conventional jets,the focused jet can achieve a longer range,higher flow rate,smaller beam diameter,more uniform flow field,and higher localized jet.With the increase of the focused hole radius r,the focusing effect of the focused device structure becomes better and better,but the stability of the focused jet becomes worse and worse;With the increase of the distance h between the nozzle and the focused hole,the focusing effect of the focused device structure becomes better and better,but the stability of the focused jet increases first and then decreases;With the increase of the focused hole length L,the focusing effect of the focused device structure becomes worse and worse,but the stability of the focused jet increases first and then decreases.Threrfore,we found that when the focused hole radius r is equare 1.2R,the distance h between the nozzle and the focused hole is equare2 R,the focused hole length L is equare R,the focused effect of the focused nozzle is great;(2)The relationship between the focused jet condition parameters and the characteristics of focused jet electrodeposition near stagnation region flow field distribution was investigated and the effects of the focused jet condition parameters on the characteristics of focused jet electrodeposition near stagnation region flow field distribution was analysed.The results show that: Compared to conventional jets electrodeposition,the area of focused jet electrodeposition near stagnation region is smaller.Moreover,this focused Jet electrodeposition high velocity fluids around the jet can reduce the thickness of flow film in the wall jet region,which may benefit for reducing stray currents around the jet;When the electrolyte flow rate is constant,with the increase of the gas pressure difference ΔP,the diameter of the jet and the stagnation region of the focused jet electrodeposition becomes smaller and smaller,and the thickness of the flow film in the wall jet region becomes smaller and smaller.Besides,the field distribution is getting better and better;When the gas pressure difference ΔP is constant,with the increase of the electrolyte flow velocity v,the focused jet electrodeposition not only increases the diameter of the jet,but also increases the thickness of the flow film in the wall jet region and the area of the stagnation region.However,the uniformity of the cross-sectional flow velocity of the focused jet decreases slightly.(3)In the electrodeposition mode(flow field-electric field coupling),the relationship between the focusing jet condition parameters and the electric field distribution characteristics of the focused jet electrodeposition cathode substrate was studied and the influences of focused jet fluid dynamics parameters(gas pressure difference ΔP,electrolyte flow rate v)on the characteristics of the focused jet electrodeposition cathode electric field distribution was analyzed;The results show that:Compared with Jet ECD,the electric field distribution of the focused jet electrodeposition is smaller,and the uniformity of the electric field distribution in the range of the electric field distribution is improved.In addition,the current density at the center of the nozzle and the stray current around the nozzle is increased;When the electrolyte flow rate is constant,with the increase of the gas pressure difference ΔP,the electric field distribution area of the focused jet electrodeposition gradually decreases,and the uniformity of the electric field distribution in the range of the electric field distribution is improved.Moreover,the current density at the center of the nozzle is becoming larger.Besides,stray currents around the nozzle are getting smaller;When the gas pressure difference ΔP is constant,with the increase of the electrolyte flow velocity v,the electric field distribution area of the focused jet electrodeposition gradually increased,and the uniformity of the electric field distribution in the electric field distribution area is reduced.In addition,with the increase of electrolyte flow rate,the current density at the center of the nozzle and the stray current aound the nozzle are increasing.(4)Based on the developed experimental system of Focused Jet Electrodeposition,on the basis of optimizing the jet,the experiment of focused jets electrodeposition was conducted in order to fabricate good localization deposition layer.Besides,the effects of focused jet condition parameters on the three-dimensional profile of the deposition layer and the selective(localization)of the deposition layer was analyzed.The results show that: When the gas pressure difference ΔP=7500Pa and the electrolyte flow velocity v=7.5m/s,the localization(consistency)of the deposited layer is the best;The experimental results are in good agreement with the simulation;Compared with jet electrodeposition,the deposition layer fabricated by focused jet electrodeposition has a greater height and a smaller diameter.Moreover,the consistency of the deposition layerdiameter and the nozzle size is better.(ie,the selectivity(localization)of the deposited layer fabricated by focused electrodeposition deposition is better);When the electrolyte velocity v is constant,with the increase of the gas pressure difference ΔP,the height of the electrodeposition deposition layer fabricated by focused jet electrodeposition is becoming larger,the diameter of the deposition layer fabricated by focused jet electrodeposition is becoming smaller.In addition,with the increase of the gas pressure difference ΔP,the slope of the deposited layer fabricated by focused jet electrodeposition is becoming larger.The consistency of the deposition layer diameter and the nozzle size is better,ie.the localization of the deposited layer fabricated by focused jet electrodeposition is better and better.When the gas pressure difference ΔP is constant,with the increase of the electrolyte flow velocity v,the height and diameter of the deposition layer fabricated by focused jet electrodeposition are becoming larger.In addition,with the increase of the electrolyte flow velocity v,the slope of the deposited layer abricated by focused jet electrodeposition is becomeing larger,ie,the localization of the deposited layer fabricated by focused jet electrodeposition is better and better. |
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