Electroless Deposition of Novel Ternary Zn-W-B Alloy Coating

In this work, ternary Zn-W-B alloy coatings were successfully deposited on alloy steel st37 by electroless plating technique. Zn-W-B coating was deposited from the bath, containing a cationic surfactant CTAB, with different ratio of zinc and tungsten metals [Zn/Zn+W=(0.1-0.9)]. Scanning electron microscopy (SEM) and X-Ray diffraction were employed to study the morphology and chemical composition of the deposits. The corrosion resistance of the coatings was investigated by electrochemical polarization. The results of SEM observation showed that, increasing the amount of tungsten metal in developed alloy, would dominate the crystalline phase on amorphous phase. The structures formed by compounds were also derived from the XRD results. The results of corrosion tests indicated that, the best corrosion resistance presented, when the equal amount of metals used (i.e. 0.5 for each).