Study On The Preparation And Performance Of Conductive Polymer Polyaniline Composite Coating

Metal corrosion has caused enormous economic losses and serious safety hazards to society.Studying green and functional anti-corrosion coatings is the goal in the field of anti-corrosion.Polyaniline(PANI)has the characteristics of easy synthesis,low cost,unique redox mechanism and anti-corrosion performance,and has attracted extensive attention in the field of anti-corrosion.The nano-semiconductor TiO2 or g-C3N4 and PANI are prepared into the composite coating,which can change the electrical and electrochemical properties of PANI,and obtain the PANI coating with a more compact and stable structure.Under illumination,TiO2 and C3N4 have excellent photoelectric effect,which can combine with PANI to form a photocathodic protection on the metal.In order to obtain the advantages of photocathodic protective materials and PANI,the TiO2 and PANI composite coating or g-C3N4 and PANI composite coating were prepared by chemical oxidation polymerization.Using fourier transform infrared spectroscopy(FT-IR),ultraviolet visible diffuse reflectance(UV-Vis DRS),X-ray diffraction(XRD),scanning electron microscopy(SEM)to analyze the molecular structure,absorbance,crystalline state and coating morphology.The corrosion resistance of the coating was determined by using polarization curves,AC impedance and scratch immersion experiments.The results show that:(1)The TiO2-PANI double-layer coating improves the compactness and dispersity of the coating compared to the PANI coating.Anti-corrosion test shows that TiO2-PANI double-layer coating under ultraviolet light showed photocathodic protection effect on the metal.The protection of TiO2-PANI double-layer coating on stainless steel in NaCl solution under U V light is the synergistic result of physical shielding of coating,anti-corrosion effect of PANI and photocathodic protection.(2)The PANI/TiO2 composite coating with TiO2 nanoparticles has improved compactness and the filler has good dispersibility.The anti-corrosion performance of PANI/TiO2 composite coatings at different ratios in NaCl solution showed that the photoelectric response of aniline:TiO2 composite coating with 1:3 ratio is the most obvious,and the photocathodic protection effect is the most significant.The composite coating with aniline:TiO2 ratio of 1:2 in the dark state has the best anticorrosive effect.(3)The corrosion resistance test in hot dilute H2SO4 solutions simulating fuel cell environments shows that the corrosion potential of PANI/TiO2 coating is obviously increased and maintained in the passivation region of metal.And the PANI/TiO2 composite coating under illumination showed photocathodic protection effect on the metal.Under UV illumination,the protection of the PANI/TiO2 composite coating on stainless steel is the synergistic result of physical shielding of the coating,anodic protection of PANI and photocathodic protection.(4)Compared with the PANI/TiO2 composite coating,the PANI/g-C3N4 composite coating broadens the absorption range of the coating.The PANI/g-C3N4 coating under illumination showed photocathodic protection effect on the metal.Under the visible light,the protection of the stainless steel by the PANI/g-G3N4 coating is the synergistic result of physical shielding of coating,anti-corrosion effect of PANI and photocathodic protection.