ELECTROCHEMICAL SCANNING TUNNELING MICROSCOPE STUDIES OF INITIAL PITTING CORROSION IN 18/8 STAINLESS STEEL
不锈钢点腐蚀发生的早期过程Ⅱ.电化学扫描隧道显微研究

The surface topographies of stainless steel in an early stage of pitting corrosion were imaged by a home made electrochemical scanning tunneling microscope (ECSTM). The influences of potential, chloride and time on the surface topographics were examined in nanometer spatial resolution corresponding to the polarization behaviors. It was further indicated that the local breakdown of passive film and micropitting corrosion always occur in the potential region which was much more negative than that of the ordinary critical pitting corrosion. The initiation, temporary development, and repassivation of the metastable micro pitting corrosion were important reactions during an very early stage of pitting corrosion. The tendency of metastable micro pitting corrosion of approximate 10 nanometer geological size increased with polarized potential. Chloride appeared un uniform distribution on the surface and induced the local breakdown of passive film for the 18/8 stainless steel in NaCl solution.