利用电化学测量方法测量纯镍在3.5%NaCl溶液中,静水压力为0 MPa和8 MPa条件下的点蚀击破电位和孕育时间.分析得到纯镍在不同静水压力下点蚀击破电位的理论精确值,利用随机分析方法分析纯镍在静水压力下的点蚀机制.实验结果表明静水压力对纯镍的点蚀过程有着重要的影响,在静水压力下纯镍的点蚀行为和机制发生了改变.在较高的静水压力下,纯镍点蚀产生的敏感性增强,点蚀击破电位E_(critical)明显降低;纯镍点蚀诱导时间也变短,其点蚀产生的机制发生了改变;在较高静水压力下,纯镍表面的钝化膜活性增强,恶化了纯镍的耐蚀能力.
The pitting breakdown potential and pregnant time of pitting for pure nickel in neutral 3.5% NaCl solution under hydrostatic pressures of 0 MPa and 8 MPa at room temperatures were determined by means of electrochemical measure method. Then the theoretical value of pitting breakdown potential of pure nickel under different hydrostatic pressures was deduced, and the relevant pitting mechanism of pure nickel under hydrostatic pressure was discussed by stochastic analysis method. The experimental results revealed that the hydrostatic pressure exhibited a strong influence on the pitting process of pure nickel,which change the pitting behavior and pitting mechanism. Under high hydrostatic pressure, the susceptibility to pitting increased and the theoretical value of pitting breakdown potential of pure nickel decrease obviously, while the pregnant time of pitting for pure nickel shortens. Thereby the pitting stochastic model changed. The high hydrostatic pressure enables the activity of passive film on pure nickel to be enhanced, and thus the corrosion resistance of nickel was deteriorated.
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