Evaluating water transport through high solid polyurethane coating using the EIS method

Abstract

Buried pipelines are commonly coated with high solid polyurethane to prevent corrosion. The diffusion of water through the coating plays an essential role in the performance and endurance of the coating. This study focuses on the evaluation of water diffusion through polyurethane coatings. The effects of thickness and ambient temperature on water diffusion through polyurethane, which is coated on mild steel and immersed in 3.5% (weight fraction) NaCl solution, are evaluated using electrochemical impedance spectroscopy (EIS). Experimental observations clearly indicate that the water diffusion coefficient strongly depends on service temperature and the thickness of coating. Higher temperature (lower than T g ) increases water uptake of the polymer but no measurable changes were observed for the temperature change studied. EIS results show that the mechanism of corrosion does not change in the range of thicknesses and temperature investigated in this study.

Predicting water transport in multilayer coatings

“…. Note, that coatings, designed to act as a barrier have permeabilities in order of 10 À9 À10 À10 mol m À1 s À1 [3,17].…”

“…For water uptake (q 0 ¼ 0, a ex ¼ 1) the solution reads (17) To obtain and compare the sorption isotherms of the various systems, the parameter f is recovered by fitting the solution to the water uptake data (Fig. 5).…”

Study on effect of duration of the ultrasonication process on solvent‐free polyurethane/organoclay nanocomposite coatings: Structural characteristics and barrier performance analysis

“…31,32 One of the methods commonly used to study coatings performance is EIS. One of the ubiquitous natural molecules that damage the substrate is water.…”

Detection of corrosion-induced metal release from tinplate cans using a novel electrochemical sensor and inductively coupled plasma mass spectrometer

“…It has been documented that metal release is usually caused by corrosion which can be detected by the electrochemical methods. Lacquered tinplate is a coating/metal system and its electrochemical signal during corrosion process can be detected by the electrochemical techniques, such as electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) detections (Liu et al, 2009;Zhang et al, 2009;Rezaei et al, 2010;Zhu et al, 2010;Betova et al, 2010). Thus, analyzing the metal release from a corrosion perspective is very important.…”