Cyanide-free silver electroplating process in thiosulfate bath and microstructure analysis of Ag coatings  

硫代硫酸盐无氰镀银工艺及银镀层微观组织分析(英文)

作　　者：任凤章[1] 殷立涛[1] 王姗姗[2] A.A.VOLINSKY 田保红[1] 

机构地区：[1]河南科技大学材料科学与工程学院,洛阳471023 [2]洛阳轴研科技股份有限公司,洛阳471039 [3]Department of Mechanical Engineering,University of South Florida

出　　处：《Transactions of Nonferrous Metals Society of China》2013年第12期3822-3828,共7页中国有色金属学报（英文版）

基　　金：Project (50771042) supported by the National Natural Science Foundation of China;Projects (104100510005;2009HASTIT023) supported by the Program for Science and Technology Innovation Talents of Henan Province,China

摘　　要：Cyanide-free silver electroplating was conducted in thiosulfate baths containing AgNO3 and AgBr major salts, respectively. The effects of major salt content and current density on surface quality, deposition rate and microhardness of Ag coatings were investigated. The optimized electroplating parameters were established. The adhesion strength of Ag coating on Cu substrate was evaluated and the grain size of Ag coating was measured under optimized electroplating parameters. The optimized AgNO3 content is 40 g/L with current density of 0.25 A/dm2. The deposited bright, smooth, and well adhered Ag coating had nanocrystalline grains with mean size of 35 nm. The optimized AgBr content was 30 g/L with current density of 0.20 A/dm2. The resultant Ag coating had nanocrystalline grains with mean size of 55 nm. Compared with the bath containing AgBr main salt, the bath containing AgNO3 main salt had a wider current density range, and corresponding Ag coating had a higher microhardness and a smaller grain size.采用硫代硫酸盐无氰镀银工艺,分别以AgNO3和AgBr为主盐进行镀银。研究主盐含量、电流密度对Ag镀层表面质量、沉积速率和显微硬度的影响,并优化电镀参数。分析优化工艺下的Ag镀层结合强度和晶粒尺寸。结果表明:在AgNO3体系中,AgNO3最佳用量为40 g/L,最佳电流密度为0.25 A/dm2,制备的Ag镀层光亮平整,与基体结合良好,晶粒尺寸为35 nm。在AgBr体系中的最佳AgBr用量为30 g/L,最佳电流密度为0.20A/dm2,与基体结合良好的Ag镀层的晶粒尺寸为55 nm。与AgBr体系相比,AgNO3体系适用的电镀电流密度范围较宽,制备的Ag镀层显微硬度高,晶粒尺寸小。

关 键 词：cyanide-free silver electroplating THIOSULFATE current density bonding strength grain size 

分 类 号：TG174.44[金属学及工艺—金属表面处理]