Evaluation of organic coatings for corrosion protection of condensing economizers

摘要

A corrosion protection of Stainless Steel (Grade 304) with low-cost commercial organic coatings (paints) was investigated in this study. Air sprayed Polyurethane (PU)-, Epoxy- and Acrylic-based commercial paints on the above substrate were tested for their anticorrosion properties in prospect of potential application for the protection of condensing economizers from industrial flue gases. PU and Epoxy coatings exhibited better corrosion protection efficiency of stainless steel than the acrylic coatings with values of 40, 39 and 28.1% respectively. This is in total agreement with corrosion current density trend calculated from potentio-dynamic polarization curves. Corrosion rates of coatings in 3.5% wt NaCl aqueous solutions were calculated at 0.065, 0.067 and 0.071 mpy for Epoxy, PU and Acrylic coatings respectively. Condensation phenomena and water collection rates (WCR) at various conditions are also provided. The highest WCR exhibited on the epoxy coatings reaching 1.987 ml m~(-1)h~(-1) at 40°C and 100% RH. These data provide a full dataset for the designers of condensing economizer systems willing to incorporate organic coatings either at structural components or as touch up solutions.