Development of environmentally friendly nonchrome conversion coating for electrogalvanized steel

The toxicity of chromium salts created environmental and health-related concerns and generated a great deal of interest in developing chrome-free conversion coatings. Most of the new developments are based on organic coatings. In the present work, some silanes were used to coat electrogalvanized (EG) steel sheets for corrosion protection. Contact angle measurement, Tafel studies, electrochemical impedance spectroscopy (EIS) and salt spray tests (SST) were conducted to investigate the efficiency of the organic coatings for the corrosion protection. It was found that pH of a silane solution is important in the adsorption of silanes on the EG steel surface and, therefore, affected its corrosion resistance.