Development of Electrodeposition Process Based on Chloride Electrolytes for Bulk Pure Fe with Plastic Deformability

Abstract

Contamination with sulfur causes deterioration of the mechanical properties of electrodeposited nanocrystalline iron (Fe) and its alloys. However, it is difficult to avoid this contamination for electrodeposition from a sulfate bath. In this study, we explored the processing parameters required to produce thick plates of electrodeposited Fe from a chloride bath containing no sulfur and examined the resulting mechanical properties. In a simple bath consisting only of iron chloride, the long electrodeposition required to produce bulk samples could not be performed due to the precipitation of hydroxide, which caused the voltage to increase beyond the limits of the equipment. The addition of ammonium chloride inhibited the generation of hydroxide and stabilized the voltage during the electrodeposition. In addition, a higher bath temperature suppressed the formation of micro-cracks on the surface of the electrodeposits. Furthermore, the appearance of voids on the surface was reduced by increasing the concentration of the iron source and decreasing the current density. On the basis of these results, we prepared a bulk sample of electrodeposited Fe with a body-centered cubic structure and average grain size of ∼5 µm. The electrodeposited bulk Fe exhibited a tensile strength of 649 MPa and good elongation of 13.9%.