In-situ generation and application of nanocomposites on steel surface for anti-corrosion coating

• In-situ generation of nanoparticles made using polyamic acid (engineered polymer).
• Active–passive behaviour was studied using electrochemical impedance spectroscopy.
• Nano-composite coating as an anti-corrosion system for steel was shown.

Thin organic coatings directly on steel sheets provide excellent barrier protection in saline environment and meet deformability demands, but fail in providing active corrosion protection. We have put an effort to solve this problem by formulating composite coatings using in-situ generation of metal oxide nanoparticles (NPs) in the polymer matrix. Here we present a new synthesis method of high performance polyetherimide composite with TiO2, MgO, and Al2O3 nanoparticles and their application for anti-corrosion coatings in saline environment. We observed that in-situ synthesis of these metal oxide NPs in the polymer curing process leads to evenly distribution and uniform size of nanoparticles. Thermo-mechanical property was analyzed for these three kinds of free-standing composite film to assess elasto-plastic behaviour and compared to mother polymer film. Results indicated that thermal stability and elastic behaviour of composites film are not affected to the great extent by the presence of NPs. The potentiodynamic and the electrochemical impedance studies on these composite coated steel panels were carried out to identify active–passive behaviour. Results showed active corrosion protection from nanocomposite coating based on TiO2 and barrier protection was noticed from nanocomposite coating based on MgO and Al2O3.