A comprehensive study on the jet electrodeposition method for fabricating 3D structures with overhangs

Electrochemical additive manufacturing (ECAM) is gaining increasing attention in the fabrication of micro/nano-scale metal structures due to its advantages, such as high forming accuracy, low porosity, absence of thermal stress, etc. Among various ECAM techniques, interest is increasingly enhanced in jet electrochemical deposition (Jet ECD) approach due to its ultra-high deposition rate. Despite its inherent advantages as a high-efficiency ECAM process, Jet ECD still faces challenges for automated fabrication of complex 3D structures due to suitable control of the jetted flow. In the present study, a step-delay method based on Jet ECD is proposed. This approach allows for the automation of the fabrication process using commonly employed stepper motor translational stages, seamlessly integrating it into the current 3D printing framework. By adjusting the moving time of the stages and the delay time between two successive steps, agreement between the movement of the stages and the temporally nonlinear electrodeposition rate can be achieved. Consequently, complex 3D copper structures with overhangs, such as 3D helical structures, are successfully obtained. It is found the deposition rate can be as high as similar to 25 mu m/min, and the maximum overhanging angle that can be achieved by the automated step-delay method is similar to 60 degrees. The mechanical properties of the deposited copper using the proposed approach have been thoroughly characterized by various techniques. The average grain size of the deposited copper can be as small as 0.5 mu m without preferred orientation. It also shows that highly dense structures with porosity of less than 0.1% can be obtained, and the elastic modulus of the deposited copper ranges from 3 - 20 GPa. In future studies, it is anticipated that larger overhanging angles can be achieved by incorporating image recognition techniques in the step-delay method.