INFLUENCE OF TEMPERATURE ON CALCAREOUS DEPOSIT DEPOSITION UPON CATHODICALLY POLARIZED STEEL IN SEA WATER

Experiments have been performed where cylindrical 1018 steel specimens were polarized to -0.900 V.(SCE) in natural sea water at 24 and 3C and with rotation speeds of 0 and 0.83 Hz. The nature of the calcareous deposits which formed was characterized, first, by monitoring current density during the experiments and, second, by post-test SEM investigation of deposit morphology and thickness and by EEDS analysis of deposit composition. The dependence of cathodic current density and film composition upon temperature and exposure time has been established, and the observed trends have been interpreted in terms of (1) the temperature dependence of the solubility limit and relative nucleation and growth rates for Ca and Mg rich phases and (2) possible electrical conductive behavior on the part of Mg rich deposits.