LIMITATIONS OF COPPER NITRATE ELECTROLYTE FOR FAST ELECTROCHEMICAL 3D-PRINTING

Abstract

To date, technologies based on local sintering of metal powder have become widespread for forming a metal product by 3D-printing. The disadvantage of additive manufacturing technologies based on local melting is high energy consumption, as well as the need to obtain metal powder or wire before making a product from it. The electrochemical technology of additive manufacturing, which is based on the local electrochemical deposition of metal from an electrolyte, does not have such disadvantages. An investigation of local electrodeposition of metallic copper from a nitrate electrolyte was conducted in order to determine the possibility of using this electrolyte in electrochemical 3D printing technology. Deposition was carried out using a platinum insoluble anode placed in a polypropylene capillary with a diameter of 4 mm. Cylinder-shaped coatings with a height of 100 μm and 500 μm were grown at different current densities in stationary and pulsed modes. Experimentally deposited samples were analyzed using 3D-profilometry, the surface profile was compared with the computer model and the desired coating profile. It has been established that the highest printing accuracy is achieved at a deposition current density of 20 A/dm² when a deposition thickness is below 100 μm. In these conditions, the highest deposition accuracy is observed - 87% of the coating is deposited within the expected borders, and only 9% - outside these borders. The deposited metal is densely packed and has a finely crystalline structure. An increase in the deposition thickness and the deposition current density and the use of a pulse mode led to a decrease in the accuracy of the deposition and the quality of the coating due to the appearance of diffusion limitations and the formation of dendrites. Thus, the nitrate electrolyte allows for high-quality local electrodeposition of copper of a small thickness (up to 100 μm) at a current density of up to 20 A/dm². Further studies of electrochemical 3D printing processes should be directed to the search for an electrolyte and deposition conditions that allow metal local electrodeposition with an accuracy no worse than that obtained in this work, but for thicknesses of up to 1 mm and more.