Protection Performance of Doped and Eigenstate Polyaniline on Stainless Steel

Polyaniline (Pani) doped with phosphoric acid was synthesized on stainless steel by electrochemical method and the eigenstate Pani was prepared by immersing the doped Pani in 1 mol/L NH4OH for 4h.The doped pani and eigenstate Pani were characterized by scanning electron microscopy and fourier transform infrared spectroscopy.Their protection performance on stainless steel in 1 mol/L Na2SO4 solution was investigated through potentiodynamic polarization and potential-time curves.Results indicated that there were holes on both surfaces of the doped and eigenstate Pani.The corrosion potential of both kinds of Pani positively shifted remarkedly.The eigenstate Pani protects stainless steel by mechanical isolation.The doped Pani protects stainless steel by passivation,and its protection time is longer than that of the eigenstate Pani.