A novel environmentally friendly mixed complex bath for electrodeposition of a thin film of crack-free FeCrNi stainless steel-like

Stainless steel codeposition on a low-cost substrate is crucial because of economic factors. In this work, codeposition of FeCrNi thin film was successfully prepared galvanostatically from a novel environmentally friendly mixed complex (glycine-formate) bath on a steel surface. The novel bath is characterized by using environmentally benign Cr(III) rather than Cr(IV), at pH 7, applying low current density (i_d) at 25 °C, and finally producing crack-free nanostructured FeCrNi films with up to 18% Cr. The obtained FeCrNi thin film has a composition resembling that of stainless steel 304 (Ni 8% and Cr ~ 18%). The study was carried out using potentiodynamic polarization curves, chronoamperometric analysis, and anodic linear stripping voltammetry (ALSV), complemented by a scanning electron microscope and X-ray diffraction analysis. The atomic absorption test showed an acceptable range of Cr content (from 13.76 to 18.75 At. %) depending on the practical circumstances. The Cr% is enhanced slightly by decreasing the i_d and pH or raising the temperature. At deposition times of 20 and 60 min, the Cr content slightly decreased with increasing i_d. For example, the Cr content decreased from 17.88% (at 0.48 mA cm⁻²) to 13.98% (at 2.41 mA cm⁻²) and decreased from 17.14% (at 0.48 mA cm⁻²) to 13.94% (at 2.41 mA cm⁻²) respectively. The deposition of FeCrNi films has been characterized by instantaneous nucleation followed by 3D growth under charge transfer control. The phases were polycrystalline, and their grain size value was 8.93 nm. At a relatively high current density (2.41 mA cm⁻²), the coatings’ surface morphology became uniform, extremely smooth, and nearly devoid of micro-cracks. However, a low bath pH of 4.0 results in observed multiple pits of varying sizes.