Highly porous FeNi 3D foams produced by one-step electrodeposition: Electrochemical stability and mechanical properties
P. Arévalo-Cid, M. Fátima Vaz, M.F. Montemor
Abstract
Highly porous iron‑nickel foams, including the first-ever reported pure iron foam, were prepared by the dynamic hydrogen bubble template electrodeposition method and studied regarding their electrochemical stability and mechanical properties. Changes on the morphology, microstructure, and electrochemical resistance of the foams were investigated as a function of the Fe:Ni ratio by scanning electron microscopy (SEM), d.c. polarization and electrochemical impedance spectroscopy (EIS). Tensile and bending tests were carried out to evaluate the mechanical behavior of the prepared foams. Both crystalline structure and morphology are affected by the increase of Ni content, evolving from a highly porous foam with a body-centered cubic (bcc) structure to a denser material with open pores and face-centered cubic (fcc) structure. Polarization curves reveal an ennoblement of the corrosion potential as the nickel content increases. The impedance response revealed a dependence on the foam porosity. An increased number of pores was found more detrimental to the mechanical properties of the foams, as fractures seem to propagate, preferentially by cracks due to connecting pores. As result, foams with higher Ni contents displayed better mechanical performance for both tensile and bending assays. Results show that this innovative and powerfull technique enables to design iron foams with the adequate properties required for industrial applications.