含重铬酸根硫酸溶液中磁场对铁自腐蚀状态及极化电阻的影响

EFFECT OF MAGNETIC FIELD ON OPEN CIRCUIT CORROSION AND POLARIZATION RESISTANCE FOR IRON IN SULFURIC ACID CONTAINING DICHROMATE

铁在含有一定浓度重铬酸根的硫酸中，自腐蚀状态下的阴极反应速率受重铬酸根阴极还原电子转移过程与扩散过程共同控制．外加磁场使铁的自腐蚀电位正移，且电位正移幅度随重铬酸根浓度增加而增大．在没有外加磁场时的自腐蚀电位下进行恒电位极化时，外加磁场后会出现阴极电流，磁致阴极电流随重铬酸根的浓度增大而显著增大．外加磁场会使含有一定量重铬酸根的硫酸溶液中铁的极化电阻显著下降．通过对磁场作用进行模型化，分析了磁场作用的动力学机理．磁场对阴极扩散过程的加速作用导致了自腐蚀电位正移及磁致阴极电流，而磁场引起自腐蚀电位的正移是引起极化电阻减小的主要原因．

Cathodic reaction rate at open circuit Potential for iron in sulfuric acid containing dichromate ion was controlled by both electron transfer process and diffusion process. Magnetic field made the open circuit potential move toward positive direction, and the magnitude of open circuit potential variation increased with increasing dichromate concentration. When iron was potentiostatically polarized at the potential which was equal to the open circuit potential in the absence of magnetic field, cathodic current was observed when magnetic field was imposed, and such magnetic field induced cathodic current increased with increasing dichromate concentration. Imposed magnetic field obviously decreased the polarization resistance for iron in sulfuric acid containing dichromate ion. The kinetic mechanism of magnetic field effect was analysed by theoretical modeling. Positive shift of open circuit potential and the occurrence of magnetic field induced cathodic current were caused by the accelerating effect of magnetic field on cathodic diffusion process, and the decreasing of polarization resistance was attributed mainly to the positive movement of open circuit potential.