Self-healing Anticorrosion Coatings for Gas Pipelines and Storage Tanks

Abstract

In the present study, chitosan based self-healing anticorrosion coatings were prepared by layer by layer(lbl) addition of chitosan (Ch) and polyvinyl butyral ({PVB}) on mild carbon steel substrate. Chitosan coatingsexhibited enhanced coating stability and corrosion resistance in aggressive environments by the applicationof a {PVB} top layer. Chitosan layer in the lbl coatings have been modified by using glutaraldehyde (Glu)and silica ({SiO}2). Performance of different coatings was tested using electrochemical impedance spectroscopyand immersion test. The best anticorrosion performance was observed in case of 10 \% Ch\_SiO2\_PVB coatings,which withstand immersion test over 25 days in 0.5 M salt solution without visible corrosion. 10 \% Ch\_SiO2 coatings without the {PVB} top layer didn’t last more than 3days. Application of {PVB} top layer sealedthe defects in the chitosan pre-layer and improved its hydrophobic nature as well. Raman spectra and {SEMof} steel surfaces after corrosion study and removal of {PVB}\_Ch/Glu\_PVB coatings showed a passive layerof iron oxide, attributing to the self-healing nature of these coatings. Conducting particle like graphenereinforcement of chitosan in the lbl coatings enhanced corrosion resistance of chitosan coatings.