| dc.description.abstract | Corrosion is a persistent problem faced by manmade structures made up of metal alloys. Aluminum 2024-T3 is high strength, light weight alloy used in aerospace applications. It suffers from the problem of corrosion due to its composition. Cold rolled steel is employed in structural applications but undergoes severe corrosion when exposed to corrosive conditions. Coatings are one of the best avenues to protect metal alloys from the corrosion. Traditional coating systems such as barrier type coatings, metal rich coatings, and inhibitor containing coatings have their own drawbacks. Conducting polymers (CPs), such as polypyrrole (PPy) can be used for the corrosion protection of the metals. Redox activity in conjunction with corrosion inhibiting ion release ability make CPs as a promising candidate for the replacement for hexavalent chromates. However CPs porous nature, inherent insolubility, stiff chains, and poor mechanical properties pose significant hindrance towards their implementation in coatings. In order to overcome the problems associated with the CPs and to extract maximum functionality out of them, conducting polymer containing composites (CPCC) were developed. CPCC combines CPs with inorganic pigments in unique ways and pave for excellent properties. In this work, series of composites of PPy/Inorganic pigments (aluminum flakes, iron oxide, micaceous iron oxide, and titanium dioxide) were synthesized by ecofriendly, facile chemical oxidative polymerization. Core and shell morphologies of PPy with titanium dioxide and iron oxide were synthesized and employed for the corrosion protection of cold rolled steel substrate. Various dopants such as phosphate, nitrate, molybdate, vanadate, and tungstate were incorporated in the backbone of PPy. These composites were characterized for morphology, elemental composition, and conductivity by various techniques. Furthermore coatings based on these composite pigments were formulated on Aluminum 2024-T3 and cold rolled steel substrates. These coatings were exposed to salt spray and prohesion test conditions and electrochemically evaluated against corrosion by Electrochemical Impedance Spectroscopy (EIS), DC Polarization, galvanic coupling and Scanning Vibrating Electrode Technique (SVET). Effect of solvent in the composite synthesis and PPy morphology in the final composite on the protective properties of coating was investigated. Effect of corrosion inhibiting anions on the final performance properties was also evaluated. | en_US |
