孔蚀过程中电化学噪声的“白噪声”水平与截止频率的研究

ON THE“WHITE NOISE”AND CUT-OFF FREQUENCY OF ELECTROCHEMICAL NOISES DURING PITTING CORROSION

研究了恒电位条件下 Cl^-浓度和电位对于电流噪声在极低频率下的“白噪声”水平的 Gw 与截止频率 f 的影响,同时研究了恒电流条件下阳极电流密度对于电位波动噪声特征的影响。研究结果表明,在电极表面未形成典型的蚀孔的条件下,f_c和 Gw 可以作为评估孔蚀倾向的参数。

The influences of applied potential,Cl^(-)-concentration and applied anodie current density on the characteristic parameters of electro- chemical noises during pitting corrosion were investigated.It was found that the effects of Cl^(-)-concentration and applied anodic current density on the apparent value of n of 1 /f^n noises were negligible, while the level of the“white noise”at very low frequencies Gw and the cut-off frequency f_c of spectral power density curves increased with increasing Cl^(-)-concentration and applied anodic current density and with raising of electrode potential if no real pits could be detected on the surface of passivated metals.It is inferred that Cl^(-)-concen- tration and applied anodic current density only influence the rate of occurrence of pit nuclei but do not influence the processes of growth and re-passivation of single pit nucleus,and that the resistance of passivated metals can be evaluated by Gw and f_(?) during pit incubation period.