抄録
One of the principal means of corrosion protection of metal is thin organic coatings. These coatings often deteriorate because water or ionic species penetrate into the polymer coating. Since both the capacitance and resistance of a polymer coating change as it absorbs water, the use of electrochemical impedance spectroscopy is expected to measure the coating property by non-destructive manner. However, coatings used for oil storage tank are very high performance, and it hasn't revealed yet how the coatings deteriorate or the impedance behavior change. In this study, we discussed the degradation mechanism of a high performance coating by impedance analysis. We measured impedance of coating of bottom plate at oil storage tank and coating after corrosion accelerated test at laboratory. As accelerated test, we employed temperature gradient immersion test and immersion test in high-temperature water. In the former test, blisters occurred on the specimen, but impedance behavior was the same as the initial condition approximately. So, we immersed the specimen into high-temperature water. Good agreement was obtained between the measured impedance data and results of degradation area of oil storage tank.
