Electrochemical Test Methods in Corrosion Control

摘要

Electrochemical techniques has been widely utilised in the last few years as a tool, together with surface analysis, to investigate the protecting properties of organic coatings for metals. The possible defects and limitations of coatings are detectable with the use of such experimental techniques. The metal coated system is generally fairly complex and consists of a metal substrate (mild steel, aluminium, zinc, magnesium, stainless steel, etc.), a surface pretreatment (chromatation, phosphatation, or mechanical surface preparations, etc.) and some layers of paint with different chemical and physical properties (adhesion promoters, primers, intermediate layers and top coatings etc.). All these parameters can influence the electrochemical behaviour measured by electrochemical impedance spectroscopy (EIS) which is the most popular electrochemical technique to asses the coating performance, and therefore also data analysis have to take in account carefully the specific characteristics of the protecting system. The aim of this work is to introduce the approach of electrochemical impedance data interpretation of organic coated metals, showing some examples relevant to different metal coated systems.