Protection of mild steel against corrosion by polynitroaniline films

Electrochemical polymerization of o-nitroaniline was carried out using graphite electrode in hydrochloric acid medium. The electrochemically synthesized polynitroaniline (PNA) was used to modify the surface of mild steel against corrosion by chemical method. The corrosion behavior of the modified steel surface was tested by weight-loss, potentiodynamic polarization and electrochemical impedance spectroscopic technique in 1N solutions of H2SO4, HCl and NaCl at 303 K. The results indicated that the surface modification of steel specimens enhanced the resistance to corrosion in the above corrosive media. The corrosion protection offered by PNA was due to the formation of its stable layer on the surface of steel. Ecorr of the modified steel specimen was in the passive region and thus inhibits the corrosion process. The surface of the steel specimen before and after treatment with PNA was studied by SEM images. The FTIR spectra of the polymer and the compound collected from the modified samples after polarization were recorded. The process of corrosion inhibition and protection of PNA film on steel was established.