Shu Yude

Electrochemical behaviors of Zn-Fe alloy and Zn-Fe-TiO2 composite electrodeposition

Electrochemical behaviors of Zn-Fe alloy and Zn-Fe-TiO2 composite electrodeposition in alkaline zincate solutions were studied respectively by the methods of linear potential sweep and cyclic voltammetry. From the results it can be concluded that Zn shows under potential deposition, Zn-Fe alloy codeposition is anomalous codeposition and Zn-Fe alloy cathode polarization is increased with the introduction of additive. From the view point of electrochemistry, the reasons that the content of Fe in the Zn-Fe coating changes with the composition of the electrolyte and the process conditions altering and the relationship between the content of Fe and the appearance of the coating are interpreted. The cathode polarization of Zn-Fe alloy codeposition is enhanced obviously with addition of additive. In the course of composite electrodeposition, TiO2 has less promotion to electrodeposition of zinc ions than to iron ions, while the electrodeposition of iron ions improves the content of TiO2 in composite coating, which is in agreement with the results of process experiments.

Potential’s fluctuation of rust preventing oil film during its degradation

Potential’s fluctuation of rust preventing oil film during its degradation was studied using wire beam electrode. Being non-destructive and simple, potential measurement is a very repetitive method. Other electrochemical testing method, e.g., polarization resistance, can breakdown the integrity of oil coating by DC current; EIS is time consuming. As a special electrochemical sensor, wire beam electrode contains 101 wires of mild steel wires, and it is helpful to improve the reproducibility of electrochemical test evidently. Using this electrode, the electrochemical parameters and their distribution which was related to underfilm corrosion process are measured directly so as to describe potential’s fluctuation of rust preventing oil film. It is pointed out that there is potential’s fluctuation on rust preventing oil film during its degradation, and this characteristic has direct effect on the self-repairing ability of rust preventing oil film. However, for the uncoated metal electrode and base oil film, there is no such behavior. It is also pointed out that inhibitors in the oil film have direct effect on its self-repairing ability.