Preparation Of Poly 3,4-ethylene Dioxythiophene (PEDOT) Coating And Its Corrosion Resistance

Metals and their alloys are prone to react with the environment and undergo degraded corrosion.Inhibiting the corrosion of metals and their alloys has always been the subject of material research and is of great significance for many applications.The conductive polymer poly3,4-ethylenedioxythiophene（PEDOT）has become an attractive anticorrosive coating for metals and its alloys due to its high electrical conductivity,high stability,and good environmental compatibility.In this paper,PEDOT coatings were prepared on the surface of active metal alloys（2024 aluminum alloy and Q235steel）by electrochemical methods.The corrosion protection properties of the substrates were studied,and the anti-corrosion and bacteriostatic mechanisms were discussed.In three different dielectrics,lithium perchlorate（LiClO4）,sodium hydrogen phthalate,and tetrabutylamine hexafluorophosphate（TBAPF6）,cyclic voltammetry and constant current method were used to prepare PEDOT coatings on 2024 aluminum alloy.The PEDOT coating was prepared on Q235 steel by constant current method.The scanning electron microscope（SEM）,Fourier infrared spectroscopy（FTIR）,and scanning vibrating electrode（SVET）analysis techniques were used to characterize the PEDOT coating.Tested by galvanic corrosion,cyclic polarization,electrochemical impedance（EIS）,and open circuit potential（OCP）,etc.2024 aluminum alloy covered with PEDOT coating in Harrison’s solution（DHS）,Q235 steel at 3.5 wt%sodium chloride Inhibition effect in（NaCl）solution.In a sulfate-reducing bacteria（SRB）solution,the electrochemical interaction between the PEDOT coating and the substrate and its ability to inhibit the corrosion of the substrate were investigated.The redox state of the PEDOT coating was electrochemically controlled,and the effect of the redox state of the coating surface on the formation of SRB biofilm was studied by laser confocal microscopy（LSCM）.The results show that TBAPF₆ on 2024 aluminum alloy,LiClO₄ can passivate Q235 steel to slow down the corrosion of the substrate.Compared with the cyclic voltammetry,the constant current method has shorter preparation time and complete and dense coating.The non-reduction process effectively increases the thickness of the PEDOT coating and enhances the corrosion protection ability of the substrate.The coating has good electrochemical stability and significantly improves the corrosion resistance of the substrate.The anti-corrosion performance of the PEDOT coating is due to the effective isolation of the intrusion of corrosive media on the metal surface,and the formation of a passivation film on the surface,which promotes the delocalization of surface charges and prevents the formation of local anode or cathode regions.PEDOT has a significant effect on the corrosion inhibition of SRB.On the one hand,it is because the surface of the PEDOT coating is dense,which promotes the passivation of the substrate and reduces the charge concentration;Removal,the continuous accumulation of electrons leads to limited late breathing.