Premium
A study of the relation between current oscillations and pitting
Author(s) -
Ma HouYi,
Yin BingSheng,
Li GuiYan,
Guo WenJuan,
Chen ShenHao,
Tang Kai
Publication year - 2003
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.20030211015
Subject(s) - chemistry , current (fluid) , relation (database) , thermodynamics , data mining , computer science , physics
Anodic polarization behaviors of iron in pure H 2 SO 4 and three mixed acidic solutions, H 2 SO 4 + NaCl, H 2 SO 4 + NaNO 3 and H 2 SO 4 + NaCl + NaNO 3 , were investigated. The potentiodynamic sweep curves showed that the current densities rose and dropped irregularly in H 2 SO 4 + NaCl solution at the more anodic potentials since the iron surface suffered pitting attack in the solution, but the pitting corrosion was inhibited effectively in the presence of nitrate ions. The surface morphological measurements indicated that pits appeared on the iron surface in H 2 SO 4 + NaCl solution and only a few unobvious corrosion spots were observed in H 2 SO 4 + NaCl + NaNO 3 solution after the iron electrode was potentiostatically polarized at 1.3 V. The oscillatory properties of iron are associated with the susceptibility of the iron to pitting. In H 2 SO 4 + NaCl solution, the regular potentiostatic current oscillations gradually evolved into the irregular current fluctuations due to occurrence of the pitting; whereas in H 2 SO 4 + NaCl + NaNO 3 solution, the current oscillations took place regularly, like the oscillatory behavior in the pure H 2 SO 4 solution. Thus, when the higher the oscillatory frequency, the more irregular oscillatory process and the more sensitive to pitting iron occurred.