Abstract
This study examines the use of polypyrrole and polypyrrole/multi-walled carbon nanotubes composite coatings for corrosion protection of 304 stainless steel in 3% NaCl solution. Polypyrrole and polypyrrole/multi-walled carbon nanotubes composite coatings were electropolymerised on 304 stainless steel surfaces by the potentiodynamic method in aqueous sulphuric acid solutions. The coatings were characterised via cyclic voltammetry, Fourier transform infrared spectroscopy and scanning electron microscopy. The corrosion behaviour of the polymer-coated stainless steel electrodes was investigated in a 3% NaCl solution by open-circuit potential measurements, Tafel polarisation and electrochemical impedance spectroscopy. Potentiodynamic polarisation, impedance measurements and open-circuit potential data revealed that the polypyrrole and polypyrrole/multi-walled carbon nanotubes composite coatings effectively protected the stainless steel substrates from corrosion in chloride solution. However, the corrosion resistance of the substrates was reduced after longer immersion times.