MONITORING OF CORROSION UNDER CATHODIC PROTECTION CONDITIONS UTILIZING COUPLED MULTIELECTRODE SENSORS
Real-time corrosion monitoring for carbon steel materials in simulated seawater under cathodic protection conditions was conducted, utilizing coupled multielectrode sensors. It was demonstrated that the coupled multielectrode sensor is an effective real-time tool for monitoring the effectiveness of cathodic protection and for measurement of the threshold value of the protection potential for specific equipment.
MEASUREMENT OF CORROSION IN SATURATED SOLUTIONS UNDER SALT DEPOSITS USING COUPLED MULTIELECTRODE ARRAY SENSORS
The corrosion rates of type 1010 carbon steel, and types 304 and 316 stainless steels in saturated solutions under salt deposits were measured using coupled multielectrode sensors. The measurements were carried out in the presence of the following salts: KCl, NaCl, NaNO3, MgCl2, NiCl2, FeCl3, FeCl2, CuCl2, and an NaCl+NaNO3 mixture. The results indicate that the corrosiveness of the salts increased in the following order: KCl ~ NaCl ~ NaNO3 ~ NaCl+NaNO3 ~ MgCl2 < NiCl2 < FeCl3 < FeCl2 < CuCl2 for carbon steel, and KCl ~ NaCl ~ MgCl2 ~ NiCl2 ~ NaCl+NaNO3 < FeCl3 ~ FeCl2 ~ CuCl2 for type 304 stainless steel. Some inhibition of corrosion of type 316 stainless steel by NaNO3 was observed in a mixture of NaCl+NaNO3, but not in pure NaNO3 solution.
Comparison of Localized Corrosion of Fe-Ni-Cr-Mo Alloys in Chloride Solutions Using a Coupled Multielectrode Array Sensor
A multielectrode localized corrosion sensor was developed and used for comparing localized corrosion of Fe-Ni-Cr-Mo alloys in chloride solutions. Experimental results indicated that the coupled multielectrode sensor provides a rapid real-time response to changes in temperature and salt concentration. It was demonstrated that the sensor has a lower detection limit of 5×10 -11 A with respect to corrosion current and 2x10 -8 A/cm 2 with respect to the corrosion current density for the miniature electrodes used in the sensors. Key word: galvanically coupled sensor; multiple-electrode sensor; multielectrode; localized corrosion sensor; wire beam electrode; on-line localized corrosion monitoring.