A corrosion diary by EIS: Life span of solvent-free polyurethanes

 
In pipeline corrosion protection, solvent-free rigid polyurethane coatings are highly popular in transportation of water due to their harmless and environmentally friendly nature. In this research, our group monitors the life span of the developed solvent-free polyurethane coatings by using electrochemical impedance spectrocopy (EIS) in aqueous %5 NaCl solution. The corrosion protection performance and mechanism of the polyurethane coating was realized using the novel AC-DC-AC method, which includes a combination of both cathodic and anodic polarization. Physical and electrochemical behaviour of the coatings were figured out via analysis of equivalent circuits models. Traditional salt spray, cathodic disbonding, and adhesion tests have been performed to examine the performance of the coatings. We realized that the corrosion occurs stepwise in a life span examined in 1200 h as in diary. End of the corrosion diary, we draw two conclusions: i) the coatings have very high protection efficiency against the corrosion and ii) corrosion resistance observed with new AC-DC-AC method can predict long-term salt spray exposure life of polyurethane coatings.