engleski

Sensing of the Barrier Effect of Pre-Aged Industrial Coatings Under Forced Wetting and Natural Exposure Conditions

The impedance of the 18 pre-aged partial and full industrial coating systems was investigated using a quasi-solid electrical contact between the coating and the conductive polymer sensor electrode. Such an experimental setup records the temporary state of the coating, which is affected by environmental conditions, primarily coating temperature and relative humidity. Under laboratory conditions (25±1.5 °C and RH <= 50%), pre-aged coatings show Log(Z@0.1Hz/ cm2) ranging from 6.76 to 11.28. Forced wetting by the wetting solution for 5, 10 and 15 minutes results in an average decrease in the logarithm of impedance of 3.44, 4.96 and 5.59% and a maximum decrease of »20%. The wetting process is reversible, with the coatings returning to their original state after a few days of conditioning in the laboratory. To account for the temperature effect during natural exposure, the temperature dependence of the impedance of the coatings was studied in the laboratory in a temperature range from 10 to 50 °C, resulting in a maximum variation of the logarithm of the impedance of 3% for the samples in the dry state. In addition, fixed sensing electrodes were applied to the samples and the responsiveness of the system was confirmed by forced wetting of a sample that showed a significant decrease in impedance in a wetting experiment with removable electrodes. The complete set of 18 aged and 8 new samples was exposed to urban atmosphere, each with two fixed sensor electrodes, one positioned close to the sample edge and the other far from the sample edges. Air temperature, relative humidity, and coating temperature were recorded along with coating impedance for 6 months. The results show behavioral patterns for coatings with different barrier properties measured near and far from the edges under different climatic conditions during natural exposure.

corrosion ; sensor ; coatings

nije evidentirano