Effects of NaH₂PO₂ concentration and deposition potential on microstructural characteristics and corrosion properties of electrodeposited amorphous Fe-P coatings

This study reports the influence of NaH(2)PO(2 )concentration and deposition potential on the microstructural characteristics and corrosion properties of fully amorphous electrodeposited Fe-P coatings. The morphology and P content of the coatings were observed and the effect of the processing parameters on the surface roughness, deposition rate, and current efficiency were investigated. The morphology and P content of the coating varied significantly with the NaH2PO2 concentration, but the deposition potential did not significantly influence these properties. As the P content and morphology determine electrochemical corrosion properties, the deposited Fe-P film with the best anti-corrosion properties was determined by analysing the corrosion properties of the coatings in 3.5 wt.% NaCl solution through potentiodynamic polarisation and electrochemical impedance spectroscopy; the corrosion morphology and corrosion products were also characterised. This study can provide new insights into the corrosion behaviour of amorphous Fe-P coatings and provide guidelines for industrial production.