Abstract
In this work, the effect of electrolyte pH on the composition and microstructure of Zn-Ni-Mn films were investigated using EDS, XRD and SEM. The composition of Zn-Ni-Mn films are greatly affected by the electrolyte pH. Low electrolyte pH (<= 1) favors the normal deposition with very low amounts, while higher electrolyte pH leads to the anomalous deposition which decreases with increasing pH. The films prepared at low pH values show a very poor quality with rough surface while those electrodeposited at high pH value (2.5 similar to 5) are generally quite smooth, uniform and compact. Galvanostatic measurements for electrodeposition, cyclic voltammetry (CV) were used to the anodic and cathodic behavior of alloy to study the potential ranges. Anodic linear sweep voltammetry (ALSV) technique was used for the phase structure determination. The effect of pH on the film quality and corrosion performances in the films, the corrosion test was performed by the potentiodynamic anodic polarization method. The corrosion resistance of the coating films was increased towards pH = 2.5 and then decreased with increasing pH value of the electrolyte.