Prolong passivation of a novel Fe-based amorphous coating derived from high P pig iron

•The passivation tendency of a novel Fe66.59C11.70P7.58Mn0.37Si2.86Cr1.72Mo0.92B8.26 amorphous coating was studied.•This composition is a derivative from high p containing pig iron.•Corrosion monitoring of a coating was performed for 3 months.•The values of polarization resistance, RP and charge transfer resistance, rct are enhanced by 16 and 107 times, respectively, after 3 months indicating huge corrosion resistance.•Fe-based chromate, borate and phosphate phases are imparting passivation to coatings. Strong passivation tendency and excellent corrosion resistance of amorphous coatings on mild steel prepared from a newly developed novel composition (Fe66.59C11.70P7.58Mn0.37Si2.86Cr1.72Mo0.92B8.26, (atom percent) are reported. The composition is a derivative of high P containing Pig iron, and atmospheric plasma spray technique was used for coating. Current-transient response at passivating potential for each coating and MS was recorded to predict the passive tendency of the coatings. The corrosion monitoring of a coating was executed for about 3 months in a 3.5 (weight /volume%) NaCl solution at free corrosion potential to understand its corrosion immunity. Extensive impedance measurements were carried out to understand the passivation and the nature of passive film on coated samples. The monitoring experiment indicates requirement of prolong duration to achieve the passivation for lean chemistry glass coating. The Fe substituted chromate, borate, and phosphate phases on all the coatings are attributed to the excellent passivation of coatings.