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Localized corrosion caused great harm in the national economy as a common type of corrosion. Conventional electrochemical methods can only describe the metal / solution interface uniformity of the electrode kinetics, can not meet the on-site, in-situ studies localized corrosion, electrochemical scanning probe techniques have emerged. As one of the electrochemical scanning probe techniques, scanning electrochemical microscopy (SECM) can be used to study the kinetics of localized corrosion, can also be used to study the metal surface passivation film growth, destruction, corrosion occurs in situ, development in-depth study of the mechanism of submicron or nanometer spatial resolution. This thesis for the first working electrode with a platinum probe, 304 stainless steel as the base working electrode (second working electrode), the use of scanning electrochemical microscopy unique generating / receiving mode, in an acidic solution of sodium chloride, the use of surface scanning, approximation curves, cyclic voltammetry, chronoamperometry method to study the corrosion product concentration distribution of localized corrosion kinetics. The main work of this paper is as follows: 1. Probe cyclic voltammetry curves in the basic shape of the substrate corresponding to the state. Cyclic voltammetry curves, analysis of the probe associated with solution components, the probe and substrate spacing, the nature of the substrate and other conditions, determine the reaction took place on the probe and the substrate to obtain the potential and the substrate or on the probe occurred The relationship of the reaction. 2 in an acidic solution of sodium chloride, by a the probe constant height of two-dimensional (XY-axis) plane scan curve, changing the potential of the probe, the use of different reaction occurs in the probe, probe Faraday current three-dimensional imaging, Characterization 304 activity of the surface of the stainless steel substrate, and thus the spacing of the probe and the substrate activity characterized discussed. 3 continuous passivated 304 stainless different time to obtain the relation curve of of passivation time with the surface of the substrate current, it is found passivation time relationship with the substrate surface to form a stable passivation film, and can visually observe the stability relative to the other portions passivation film, the passivation film of the substrate surface the location of the defect. 304 stainless steel continuous electrical potential is applied to its surface pitting. Continuous surface scanning, a basal Faraday current map, combined with experimental results approximating curve and basement nature, explore the dynamic process of localized corrosion of 304 stainless steel. The experiments show that, after the formation of the pitting, extended over time, the surface of the 304 stainless steel with the occurrence of the phenomenon of self-repairing. 5 using the chronoamperometry method, calculation of the diffusion coefficient of the ferrous ions in the acidic NaCl solution. May then be based on the ultimate steady-state current formula, after the occurrence of corrosion phenomena, 304 stainless steel surface of the ferrous ion concentration is calculated to obtain the concentration of the specific location of corrosion products, and to further explore the development of corrosion process. Discuss the of existing SO solution 4 2 - impediment on the the pitting formation of the preliminary study, and the mechanism of the different components of the solution pitting.
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