Preparation And Anticrossion Behavior Of Nanostructured Polyaniline On Stainless Steel

Because of its reversible redox behavior, simple non-redox doping/dedoping property and high conductivity, polyaniline (PANI) has shown great promising applications in many fields such as sensors and actuators, supercapacitors, secondary cells, electrochromic, electromagnetic shielding, membrane separation, anticorrosion, and so on. PANI paints are unique in friendly-environment, anti-scratching and anti-pitting properties. Nanomaterials have a series of unique behaviors including surface effect, optical, thermal, electrical, and magnetic properties.Nanostructured polyaniline membrane was sucessedly prepared from phosphoric acid medium onto 316-stainless steel (SS) electrode by one-step or two-step potentionstatic method. The polymerization parameters, such as addition of hydrogen peroxide (H2O2), polymerization potential, potential application model, and aniline concentration, have significant effects on aniline polymerization process and formed structures. Scanning electron micrograph (SEM) shows that PANI nanofibers can be obtained without addition of H2O2 while PANI nanoparticles obtained with H₂O₂.The anti-crossive performances of PANI membrane for SS in 3.5 % NaCl solution and satured NaCl solution atmosphere have been evaluated by open circuit potential (OCP) measurement, potentiodynamic polarization technique (Tafel) and electrochemical impedance spectroscopy (EIS). A physical model containing two time constants with a Warburg element was established for PANI coated SS electrode,and the experimental data was analyzed by ZSimpWin software. The effects of polymerization condition, SS passivation pre-treatment and flash welding of PANI membrane on the anti-crossive performance of PANI membrane were also explored. Passivation treatment of SS makes the OCP of PANI/SS shift 635 mV more positive compared with that of bare SS. Flash welding improves the compactabilty and anti-crossive performance of PANI membrane. SS modified by polyaniline membrane with macroscopic pore and scratch has no obvious corrosion after exposure in strongly corrosive atmosphere for 60 days. The result clearly shows good anti-scratching and anti-pitting properties of PANI membrane. Passivation of SS by PANI is the main reason for anticorrosion.