ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY AS A METHOD TO EVALUATE COATEDALUMINUM BEVERAGE CONTAINERS .2. STATISTICAL-ANALYSIS OF PERFORMANCE

A method for evaluating commercially applied organic coatings must con sider the observed distribution of coating performance for a given pop ulation. A sample of cans was examined using electrochemical impedance spectroscopy (EIS). The low-frequency impedance (the impedance betwee n 0.01 Hz and 1 Hz) measured during the first month of exposure was an alyzed statistically and used to evaluate performance of three coating populations. To verify EIS results, comparison was made to an 8-week analysis of aluminum concentration in solution and to visual observati ons at 8 months. Statistical analysis of EIS data and visual observati ons agreed well. Coating performance was related to chemistry and cure schedule.