Each metal will form a surface potential in a certain solution, and the electrode potential is related to the nature of the metal and the composition, concentration, and temperature of the solution. When the current passes through this electrode, it is also related to the magnitude of the current passing through. The greater the current passed, the greater the change in electrode potential. In order to quantitatively understand the electrode potential change caused by the current (or conversely, the current change caused by the unit potential change), these points corresponding to the current or potential are plotted in the plane coordinate system, and the resulting curve is called polarization. curve.
In electroplating, the polarization curve is often measured with the current density as the ordinate and the potential as the abscissa. This is an important experimental means to study the electroplating process to determine a good process formula and operating conditions. The basic properties of the plating solution can be analyzed through the polarization curve, such as dispersion ability, crystal thickness, allowable current density range, the influence of additives and the influence of impurities, etc. Generally speaking, when the polarization curve has a large potential change and a large slope with the increase of the current density, the dispersion ability of the plating solution is better, and the crystallization of the coating is finer. If the current increases and the potential does not change or changes very little, the crystallization of the coating will be coarser and the dispersion ability will be poor. However, it cannot be generalized. It is still necessary to make a specific analysis of the specific plating solution before drawing a conclusion.
