Localization of jet electrochemical additive manufacturing with a liquid confinement technique

Abstract

Electrochemical additive manufacturing (ECAM) is a flexible additive manufacturing method to deposit metallic/metallic-alloys microstructures without any thermally induced residual stresses. The conventional ECAM process suffers from stray deposition leading to reduced dimensional accuracy. Therefore, this paper proposes a novel liquid confinement technique to improve the deposition localization in Jet-ECAM process. Dichloromethane was employed as a second liquid phase to confine and control the flow field distribution of electrolyte as well as localize electric field on the substrate. Thus, the stray deposition induced by spreading electrolyte and hence spreading electric field could be avoided, and the deposition localization was improved. Liquid-liquid two-phase flow model was developed to analyze the flow field characteristic of two-phase flow formed by electrolyte and dichloromethane. Both simulation and observation results indicated that the flow region of the electrolyte on the substrate was well confined by the dichloromethane. The experimental results showed that the deposition localization was improved about 43.84 % compared to that in traditional Jet-ECAM. The inter-electrode gap (IEG) had a significant effect on both electrolyte flow region and current density distribution on the substrate, which affected deposition quality. Additionally, high current density leads to coarsened grains and reduces the deposition quality. Moreover, increasing the reciprocating speed of nozzle could refine the grains of microstructure, but the deposition efficiency was reduced. By employing process parameters of IEG of 100 μm, electric current of 0.0015 A, and the reciprocating speed of 300 μm/s, micro-patterns including both lines and curves were well deposited with a width of 500 μm, height of 60 μm, and a radius of 2 mm (letters G and U) and 2.5 mm (letter D).