SECM APPLIED FOR RESEARCHING THE MICROSCOPIC MORPHOLOGY AND CORROSION BEHAVIOR OF ENAMEL COATING ON MILD STEEL IN AQUEOUS CHLORIDE SOLUTIONS

The microstructures, morphology features and the corrosion resistance of the different particle diameters of enamel coating were investigated in this paper. All enamel coating samples were immersed in 5wt.% NaCl solution. The effects of the diameter of micron-dimension enamel particles on the mild steel were discussed and the corrosion resistance of the different coatings were characterized by potentiodynamic polarization curves, scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM), the SECM was employed to identify the local reactivity and then estimate where pittings happen. In this paper, six kinds of diameter of enamel particles were sintered at 780∘C on mild steel. The results indicated that the corrosion resistance of the enamel coating immersed in 5wt.% NaCl solution improved first and then declined with the decrease of particle size. Used by SEM and SECM, the result showed that as enamel particles become more small, the binding force becomes stronger. However, as the d...