Investigations on pitting corrosion of iron in perchlorate electrolytes

The pitting potential of iron in perchlorate solutions was measured in 1 M HClO4, berate buffer (pH 9.3) and phthalate buffer (pH 5) both with additions of NaClO4. A specifically designed electrochemical cell has been used for in situ microscopic studies of the growth and geometry of pits caused by perchlorate ions. The growth rate and its dependence on the potential was determined by in situ and ex situ pulse measurements. Surface analytical studies with XPS showed a decomposition of the perchlorate ion during the pitting process. Additionally the critical pitting potential for iron in chlorate containing berate buffer solution was determined. (C) 1998 Elsevier Science Ltd. All rights reserved.