Corrosion resistance of an epoxy-polyamide coating evaluated

Corrosion resistance of an epoxy-polyamide coating was evaluated Source: Anyka - Fotolia.com

Organic coatings are the most widely used method of metal bodies protection from atmospheric corrosion. However, it is well known that the coating is permeable to water, oxygen and corrosive ions which are presented in the corrosive electrolyte. Moreover, using organic coatings, the spread of corrosive products will be prevented at the initial sites of electrolyte permeation into the metal surface. Therefore, the adhesion forces which attach the coating to the metal surface can also affect the coating corrosion performance. Different parameters including the number of pores, ionic resistance of coating against electrolyte diffusion and the cross-linking density of the coating can affect the coating resistance against electrolyte diffusion through coating matrix. Epoxy coating is one of the most used kinds of organic coatings which have been widely used to protect steel bodies from corrosion. The high cross-linking density and the high adhesion strength of the epoxy coating to the metal substrates are responsible for the high corrosion resistance of this coating .The corrosion resistance of an epoxy coating reinforced with different ratios of MIO/Al pigments was studied. The coatings properties were investigated by an electrochemical impedance spectroscopy (EIS), salt spray test, cathodic disbonding and a scanning electron microscope (SEM). B. Nikravesh from Amirkabir University of Technology in Iran and his colleagues improved the corrosion resistance of the epoxy coating using MIO (micaceous iron oxide) and Al pigments. The corrosion resistance of the purely Al pigmented coating was considerably greater than the purely MIO pigmented coating. The cathodic disbonded area of coating was decreased using MIO and Al pigments. The decrease in disbonded area was more pronounced in the presence of Al particles. This article was published in Corrosion Science, Volume 53, Issue 4, April 2011, pages 1592-1603