Effects of Immersion Temperature on the Performance of a Marine Epoxy-Based Organic Coating for Ballast Tanks

The degradation behavior of an actual marine epoxy-based organic coating for ballast tanks immersed in 3.5% NaCl solution at different temperatures was investigated by employing electrochemical impedance spectroscopy and adhesion measurements. Elevated immersion temperature (e.g., 35, 45 and 55 degrees C) could greatly deteriorate coating protective performance, including barrier properties, wet adhesion strength, water uptake and diffusion, and this effect could become more pronounced with prolonged immersion time. The water diffusion based on water sorption curves was consistent with wet adhesion strength in temperature-dependent performance evaluation of the coating. The water uptake values at the quasi-saturation stage showed the expected temperature dependence when immersion temperature exceeded 35 degrees C. Breakpoint frequency could also be used for qualitatively evaluating the temperature-dependent and time-varying coating degradation behavior efficiently.