Advanced testing procedures for high performance coatings

In the first part of this work, an integrated approach incorporating electr ochemical (electrochemical impedance spectroscopy), calorimetric (different ial scanning calorimetry), mechanical (dynamic mechanical thermal analysis) , and infrared spectroscopy (Fourier transform infrared spectroscopy) techn iques was used to characterize some organic coatings from the automotive in dustry. Comparison of the results obtained with different techniques allows not only a higher precision in the evaluation of natural or artificial deg radation, which is very difficult to obtain using traditional techniques, b ut also better data interpretation and, therefore, the possibility of under standing the different degradation mechanisms. In second part, some preliminary results concerning the comparison of salt spray exposure and EIS measurements are discussed. The statistical analysis of the results showed that the degradation mechanism in the two cases is c ompletely different and, therefore, the information which is obtained with the two testing approaches is also different. With EIS measurements obtaine d in immersion, it is possible to monitor, in particular, the barrier prope rties of the coatings, which are dominated by the presence of defects. In t he case of salt spray (without scratch), the main property to be measured i s the loss of adhesion which causes blister formation.