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建立了研究钝态金属的恒电应—恒电流(P-G)瞬态响应的微计算机在线测量系统和存在孔蚀时的 P-G 响应曲线的数学模型,由采样得到的响应曲线数据,应用蒙特卡罗法算出表征钝化膜稳定性的电化学参数。用此技术研究了一些合金钢在氯化钠溶液中的钝化膜稳定性并讨论了钝化膜局部破坏的原因。

In this paper an on-line measurement system of potentiostatic-galvanos- tatic(P-G)transient response of passive metals was established.A mathematical model for P-G response curves in the case of pitting was set up.By Monte Carlo method the electrochemical parameters which characterized the stability of passive films were calculated from the sampling data of the response curves Using the P-G transient technique one can(i) detect the breakdown of passive films,(ii)determine the electrochemical parameters which characterize the performance of pass- ire films and evaluate their stability,and(iii)analyze the cause of localized breakdown of passive films. The results for some steels in sodium chloride solution measured by this technique were presented.For 18-8 SS in 3% NaCl,the autocataly- tic effect of pitting is the cause of localized breakdown of passive film.The passive films of 25Cr5Mn2Mo steel in 3% NaCl are instable at a wide potential region.This instability comes from the dissolution of passive films themselves but doesn't relate to the auto-catalytic effect of pitting.