Interactions among localized corrosion sites investigated with electrode arrays

Interactions among local pit sites were investigated using an array of 25 e lectrodes. The 5 x 5 array consisted of closely spaced, flush-mounted 316 s tainless steel wires polarized in 0.05 M NaCl solution. Two types of intera ctions occurred when either single or rows of actively corroding pits exist ed while the remaining electrodes were initially passive. Inhibition of pit ting on nearby electrodes occurred due to ohmic potential drop near active pre-existing pits. Enhancement of pitting was observed due to alterations i n the local solution composition near just deactivated pits. The former eff ect was stronger than the latter, but the concentration effect could persis t after pit deactivation. (C) 2000 The Electrochemical Society. S1099-0062( 99)12-118-7. All rights reserved.