Chlorates induce pitting corrosion of iron in sulfuric acid solutions: An analysis based on current oscillations and a point defect model

Localized passivity breakdown of iron in chlorate- and perchlorate-containing sulphuric acid solutions: A study based on current oscillations and a point defect model

“…The current waveforms obtained under potentiostatic conditions are complex, similar with those observed previously by adding halides X − [9,10,18-21,29-33]. Indeed, oscillations emerge after the lapse of an induction period of time and the current in the passive state increases upon increasing the NaClO 3 concentration [45]. However, the current still oscillates between the active and passive states.…”

“…Thus, pitting is assigned to Cl − formed via the chemical reduction of chlorates by Fe 2+ [44]. Our preliminary results based on current oscillations and analyzed in terms of a PDM support the latter reaction path during chlorate action [45].…”

Temporal patterning of the potential induced by localized corrosion of iron passivity in acid media. Growth and breakdown of the oxide film described in terms of a point defect model

“…Temporal patterning of current was employed previously to distinguish between pitting and general corrosion of iron and to characterize various stages of pitting as well. [22][23][24]26,27 To our knowledge, only current oscillations have been observed up to date for the Fe|H 2 SO 4 system. Potential oscillations during Fe dissolution in acidic solutions have been reported rarely only in the presence of Cl À .…”

“…[14][15][16] More recently, it was shown that this periodic temporal patterning of the current becomes either complex periodic or aperiodic (chaotic) when passive Fe was polarized under potentiostatic conditions in halide (X À )-containing H 2 SO 4 solutions, where X À = Cl À , Br À , I À . [17][18][19][20][21][22][23][24][25][26][27][28] The passive Fe surface responds by producing complex spike sequences that reflect both the intrinsic dynamics of an electrochemical oscillator and the temporal characteristics of a stimulus from the dynamical systems point of view. 28,29 It is suggested that small amounts of halide species perturb the ionic, electronic and chemical properties of the passive oxide film that determine the oxide stability.…”

Effects of Chloride Ions and Nitrate Ions on the Anodic Dissolution of Iron in Sulfuric Acid Solution

“…Pitting may cause tremendous losses and damages for its unpredictable nature and rapid propagation. Chloride ions (Cl − ions) usually induce pitting by breaking down the passive film for its aggressiveness to metallic materials [1][2][3][4][5][6][7][8][9][10], so the study on the mechanisms of chloride corrosion is of theoretical and practical significance.…”