CHLORIDE-INDUCED PITTING CORROSION OF IRON IN MILDLY ALKALINE BORATE BUFFER SOLUTIONS: LOCALISED DISSOLUTION KINETICS

摘要

Chloride-induced pitting corrosion of pure iron was studied using both conventional samples and artificial pit electrodes. Experiments were conducted in solutions of 0.01M, 0.1M and 1M NaCl at pH values of 7 and 10, and in pH 8.4 borate buffer solution containing the same levels of NaCl. The pitting potential (E{sub}(pit)) of pure iron is higher in buffered solutions than in non-buffered solutions of equal chloride concentration, with ΔE{sub}(pit) decreasing with increasing chloride concentration. Transition potential values (E{sub}T) between diffusion and activation/ohmic controlled pit growth were measured and compared with E{sub}(pit) results.