Electrochemical impedance spectroscopy for studying the degradation of enamel coatings
By Dubey, R.S & Upadhyay, S.N
Published in Corrosion Science
2002
Abstract
Vitreous coatings can be used as a means for the corrosion protection of metals and alloys due to their excellent dielectric properties. Their use is of particular interest in the case of highly aggressive media (different pH levels, temperatures up to 600 °C). However, ceramic coatings exposed to aggressive agents and thermal cycles can experience devitrification and spalling problems, with the consequent loss of their protective properties. The present study uses the electrochemical impedance spectroscopy technique to characterize, in a non-destructive way, the appearance of surface defects induced by the effect of temperature and chemical attack on a vitreous enamel deposited on steel. By means of analysis of the impedance diagrams obtained, a relationship is established between the loss of the coating's protective properties and the mechanism by which the corrosion process takes place.