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通过恒电位的方法测量了在有无磁场条件下纯镁的电流-时间响应曲线,并用随机的方法对结果进行分析,研究了磁场对纯镁点蚀产生过程和点蚀成长概率的影响。磁场通过洛仑兹力产生磁流体动力学效应(Magnetohydrodynamic),显著地增加了纯Mg的点蚀敏感性:对于点蚀的产生过程,磁场的存在改变了纯镁的点蚀产生机制。在无磁场作用的条件下,纯镁的点蚀产生过程都遵循“生死异地”的B1机制;在有磁场作用的条件下,纯镁的点蚀产生过程都遵循“相同点蚀并联”的A3机制。磁场不仅增大了点蚀产生速度,而且降低了点蚀的再钝化速度。对于点蚀的成长过程,磁场提高了稳态点蚀的成长概率,更容易成长为较大的点蚀坑。
The current-time response curve of pure magnesium under constant magnetic field was measured by potentiostatic method. The results were analyzed by random method. The effect of magnetic field on pitting corrosion and growth probability of pitting corrosion was studied. Magnetohydrodynamic magnetic field generated by Lorentz force significantly increased the pitting sensitivity of pure Mg: For the pitting process, the presence of magnetic field changes the pitting corrosion mechanism of pure magnesium. Under the condition of no magnetic field, the pitting corrosion of pure magnesium follows the B1 mechanism of “life and death”. Under the action of magnetic field, the pitting corrosion of pure magnesium follows the same principle of pitting corrosion "A3 mechanism. The magnetic field not only increases the pitting production rate, but also reduces the pitting corrosion repassivation speed. For the growth of pitting corrosion, the magnetic field increases the probability of steady pitting corrosion growth, and more likely to grow into larger pits.