Studies on anticorrosive properties of thermally sprayable EVA and EVAl coating

Application of polymeric coatings is one of the methods for protection of mild steel against corrosion. In the present work, blends of different grades of ethylene vinyl acetate (EVA) with varying vinyl acetate (VAc) content viz. 18%, 28%, 40% and hydrolyzed EVA i.e., ethylene vinyl alcohol (EVAl) with low density polyethylene (PE) have been used as binder for development of anticorrosive coating. The blend compositions were characterized using differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and melt flow index (MFI) techniques for determination of melting point, degradation temperature and flow behavior respectively. The blend compositions were applied on grit blasted mild steel specimens by flame spray technique and the coated specimens were evaluated for their resistance to corrosion in salt spray, humidity and seawater. EVA/PE based compositions showed superior resistance to corrosion compared to EVAl/PE based compositions in all exposure conditions after 8 weeks. The corrosion resistance of blend compositions was also studied by electrochemical impedance spectroscopy (EIS) technique. The results indicate that EVA/PE coatings have better resistance to corrosion than EVAl/PE coatings.