Effect of bath temperature on electrodeposition behaviour and corrosion properties of amorphous Fe-P alloys obtained from additive-free chloride baths

Fe-based amorphous alloys are an eco-friendly alternative to Ni- and Co-based amorphous alloys, which are not sustainable. Herein, amorphous Fe-P alloys were electrodeposited from an eco-friendly aqueous electrolyte. The influence of bath temperature on the electrochemical behaviour during Fe-P alloy deposition was investigated using linear-sweep voltammetry, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The morphology, P content and phase structure were characterized via scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and differential scanning calorimetry. The electrochemical corrosion behaviour in 3.5 wt% NaCl solution was studied using potentiodynamic polarization curves and EIS spectra. The results showed that an increase in bath temperature leads to a positive shift in the inductive co-deposition potential and increases the reaction rate. At bath temperatures of 20-60°C, the P content in deposits varied in the range of 17.07-21.13 wt% and the phase structure was amorphous. Although the amorphous alloys lacked crystalline defects, the P content had a marginal effect on the corrosion properties, whereas the surface morphology significantly influenced the corrosion properties. The amorphous Fe-P alloys fabricated in this study exhibit superior corrosion properties to almost all electrodeposited amorphous alloys reported in the literature, demonstrating their potential for corrosion protection. (author)