Process of Electroless Silver Coated Al-Mg Alloy Powder

摘要:

利用葡萄糖和酒石酸钾钠双还原剂，通过化学还原法制备银包铝镁合金粉。实验过程中，主盐为银氨溶液，通过不同的添加速度加入还原液中，得到了微观形貌不同的复合粉体，对复合粉进行微结构分析，确定了以 2~3 mL/min 较小的速度添加主盐能够得到包覆效果良好的复合粉体，其电阻率达到了5.13×10-6 Ω·m；微结构分析银镀层沉积过程表明还原的银颗粒首先沿合金粉体的晶界处形核沉积，并作为之后反应的催化形核中心，促进银的还原沉积，镀层不断平铺生长最后得到完整均匀的镀银层。

Abstract:

The silver-coated Al-Mg alloy powders were prepared by electroless plating using glucose and sodium potassium tartrate tetrahydrate as reducing agents. The main salt Tollens’ reagent were added into the reducing agent at different rates to get the composite powders with different microscopic morphologies. The results show that the alloy powders are coated best at the adding rates of 2~3 mL/min of the main salt Tollens’ reagent and have a satisfied electrical resistivity of 5.13×10-6 Ω·m. The analysis of microstructure and deposition process indicates that the reduced silver particles are first nucleation-deposited along alloy powder grain boundaries, and then act as catalytic nucleation centers to promote the silver reduction deposition. The coating grows up continuously, and finally a complete and homogeneous silver coating is formed on the surface of Al-Mg alloy powder.