Electroless plating of silver on AZ31 magnesium alloy substrate

Electroless plating of silver on AZ31 magnesium alloys via electroless plating and organic coatings (organosilicon heat-resisting varnish), was studied. The organic coating was made by immersing the samples into organosilicon heat-resisting varnish. The applicability of this method was verified by a subsequent metallization process. In this method the organic coating acted as interlayer between the substrate and silver film. When the reaction started, silver would deposit virtually onto the interlayer surface. X-ray diffraction and SEM analysis were used to investigate the morphology of the interlayer and silver film. The silver film has a rather perfect crystal structure. And the result of the cross-cut test indicates the adhesion between the substrate and interlayer is good enough. The potentiodynamic polarization curves for corrosion studies of the coated magnesium alloys were performed in a corrosive environment of 3.5 wt.% NaCl at neutral pH (7). The result reveals: comparing with the substrate, the corrosion resistance of the coated AZ31 magnesium alloys increases distinctly. Moreover, the silver coating has perfectly antibacterial and decorative properties. The method proposed in this work is environmentally friendly: non-toxic chemicals are used. In addition, it provides a new concept for plating the metals, which are considered difficult to plate due to high reactivity.