Influences of carboxymethyl cellulose on two anodized-layer structures of zinc in alkaline solution

Two anodized-layer structures of zinc in alkaline solution were obtained by different anodic polarizations in 6 M KOH, which contained different carboxymethyl cellulose (CMC) molecular weights (MWs). The electrochemical characteristics and electrodeposition behaviors of the oxide layers, which were obtained before and after passivation, were investigated. Results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Tafel polarization curves and zinc deposition indicated that different CMC MWs showed opposite effects on the porous oxide layer and passive film. Scanning electron microscopy analyses revealed that CMC with different characteristics can influence the surface structures of the porous oxide layer and passive film.