Formation and characterization of bi-layer oxide coating on carbon-steel for improving corrosion resistance

Attempts were made to improve the corrosion resistance of carbon steel by developing an additional barrier layer of magnesium ferrite (MgFe2O4) on magnetite (Fe3O4) film formed at high temperature in aqueous medium. The magnetite film was developed by exposing the carbon steel specimen in LiOH solution at 265 degrees C for 10days. Subsequently, the magnesium ferrite (MgFe2O4) film was deposited by pulsed laser deposition (PLD) technique. X-ray diffraction analysis of the film revealed the formation of spinel phase of MgFe2O4. Relative atomic ratio of Mg and Fe estimated from X-ray photoelectron spectroscopy further confirmed the spinel phase of MgFe2O4. Scanning electron microscopy and atomic force microscopy techniques were used to analyze the film surface morphology. The corrosion behavior of the coated specimens was studied electrochemically. Impedance measurements showed an increase in impedance by more than two times in PLD coated samples compared to the Fe3O4 coated carbon-steel. (C) 2008 Elsevier B.V. All rights reserved.