CORROSION MULTI-MONITORING OF CARBON STEEL IN COASTAL AREA

The corrosion behavior of carbon steel and the atmospheric corrosiveness were monitored simultaneously by the corrosion multi-monitoring system. The system consists of a temperature and humidity chamber, a corrosion monitor, an ACM data logger, a surface reaction measurement device and a microscope. After installing the corrosion sensor and the ACM sensor in the chamber, the droplet of artificial seawater with different chloride ion concentration was added to the sensor surface, and the relative humidity was changed from 30 % to 95 % in every 12 hours. As the relative humidity increased, both the corrosion rate and the ACM current increased and the surface potential shifted to less noble. Furthermore, the obtained data was discussed for the average thickness of electrolyte layer calculated thermodynamically. The corrosion behavior was divided into three regions for thickness of electrolyte layer, and the corrosion rate showed a maximum at a thickness of about 100μm