镁及其合金表面化学镀银工艺的研究

研究了镁合金表面化学镀银的工艺:利用涂膜及化学镀的方法对镁合金进行处理,即先在镁及其合金表面涂覆有机涂膜,然后再进行化学镀.工艺利用有机涂膜充当基体镁合金与镀层之间的中间层,使基体与镀层之间不直接接触,当化学镀进行时,镀层直接在中间层表面形成.虽然镁的化学活性高,但中间层的存在使化学镀银可以在镁及其合金表面实现.以AZ31镁合金轧板为基体,采用该工艺在其表面得到了理想的银镀层.通过SEM和XRD分析了银镀层的生长过程.十字切割法测量结果表明,涂膜与基体之间的结合力能满足使用要求.用极化曲线法研究了化学镀后试样在NaCl溶液中的腐蚀行为,结果表明:化学镀后试样的自腐蚀电位明显正移,腐蚀电流远远小于基体,具有良好的耐蚀性.

Study on Electroless Silver Plating on Magnesium and Its Alloys

Electroless silver plating on AZ31 Mg alloys via electroless plating and organic coatings(organosilicon heat-resisting varnish) was studied.The organic coating was made after simple immersion of the samples in organosilicon heat-resisting varnish.In this method the organic coating acted as the interlayer between the substrate and the silver film.When the reaction started,silver would deposit virtually onto the interlayer.Metallized films-ray diffraction and SEM analysis were used to investigate the morphology of the interlayer and silver film growing process.The silver coatings have a rather perfect crystal structure.Also,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 results reveal: comparing with the substrate,the corrosion resistance of coated AZ31 magnesium alloys increases greatly.The method proposed in this work is environmentally friendly: non-toxic chemicals are used.In addition,it provides a new concept for the corrosion inhibition of magnesium alloys.