Enhanced corrosion protection of the ionic liquid doped-polypyrrole/ MWCNT composite coating on stainless steel

Composite coatings were deposited on type of 430 stainless steel (SS) by one-step electrochemical process by adding Tetra Butyl Phosphonium Bromide (TBPB) ionic liquid and Multi-Walled Carbon Nanotube (MWCNT) to the sulfuric acid-polypyrrole medium. The coating conditions were optimised by changing potential range, scan rate and number of cycles. The protectivity of all polypyrrole/TBPB and polypyrrole/TBPB-MWCNT composite coatings was investigated in NaCl (3.5%) and 0.5 M sulfuric acid solution. The composite electrode prepared in 0.02 M TBPB and 5.0 mg MWCNT medium was found to be the best protective coating. Electrochemical measurements were performed by using potentiodynamic polarization (PDP) and electrochemical-impedancespectroscopy (EIS) techniques. Althougt the corrosion protection efficiency of the coating was higher than its initial value in both media during long-term immersion until 504 h, the steel coated with the polypyrrole/TBPB/ MWCNT composite was represented more protective efficiency in H2SO4 compared to NaCl solution.