Protective Effect of Impressed Current Method on Q235A Steel in Simulated Splash Zone

The method of impressed current was used to protect Q235A steel in simulated splash zone. The experiments of protective current density, electrochemical properties, morphology observation and calculation of protective efficiency were carried out to study the effect of protective potential on the protective results. The results indicate that under the control of constant potential, the values of initial current density were very large, then decreased rapidly and gradually stabilized below 100 mA/m2. At different protective potentials, the polarization resistance of the test steel increased rapidly because of the formation of calcium/magnesium deposits on the surface. As the protection potential became negative, the diameters of the impedance arc became larger and the protective property of the film was be strengthened. If the potentials were between -850 mV (vs. SCE) and the over potential of hydrogen evolution, the protective efficiency could reach more than 98%.