Corrosion Protection of Solar-Collector Heat Exchangers and Geothermal Systems by Electrodeposited Organic Films
SourceSolar-collector heat exchangers normally experience temperatures up to 150°C (300°F), and stagnation temperatures may reach 200°C (400°F). Geothermal systems, in turn, often operate at temperatures near 250°C (480°F). Despite the presence of inhibitors, these high temperatures increase the corrosion rate of the metal to intolerable levels, thus reducing the lifetime of the system. We have found that by electrochemically depositing thin polymeric films on typical solar-collector and geothermal system materials (copper, iron, and aluminum), the corrosion rates can be substantially reduced. In particular, a 4-(p-hydroxyphenyl)-2-butanone polyphenylene oxide film subsequently treated with 2,4-dinitrophenylhydrazine on a mild steel substrate afforded minimal corrosion currents.