锌-铁合金异常共沉积中锌沉积机理的研究(Ⅱ)——Zn(OH)_4^(2-)阴极放电的交流阻抗研究  

Depositing Mechanism of Zn in Zn-Fe Alloy Anonymous Co-deposition (Ⅱ ) AC Impedance of Zn(OH)_4^(2-) Cathodic Dis-charge

作　　者：王云燕[1] 彭文杰[1] 

机构地区：[1]中南大学冶金科学与工程学院,湖南长沙410083

出　　处：《材料保护》2004年第12期1-4,共4页Materials Protection

摘　　要：根据拟定的电极反应机理对Zn(OH) 2 -4阴极沉积的交流阻抗进行了理论研究及试验测试。结果表明 :第一个得电子反应为速度控制步骤 ;电极反应过程中存在有电活性的吸附态中间产物 ,而且吸附态的中间产物是以电感的形式影响电极反应的阻抗 ;拟定的机理正确。因此 ,Zn Fe合金异常共沉积中Zn的阴极沉积机理可确定为 :Zn(OH) 2 -4=Zn(OH) 2 +2OH-;Zn(OH) 2 +eZn(OH) ad+OH-(rds) ;Zn(OH) ad+e=Zn +OH-。其中 ,Zn(OH) 2 -4阴极放电的交流阻抗例证表明 ,第二步为电极反应速度控制步骤。In order to further determinate the correctness of electrode reaction mechanism and examine whether there exist the absorbent middle products with electro-activity, according to the electrode reaction mechanism formulated in the previous works, the AC impedance of Zn(OH)_4^(2-) cathodic deposition was investigated theoretically and examined experimentally. The results indicate that the first charge transfer reaction is the rate-determining step. There exists adsorbing middle products with electro- activity in the course of e lectrode reaction, and the middle products has an effect on the impedance of electrode reaction in the form of inductance. At the same time, the correctness of supposed mechanism is also proved. Therefore, the mechanism of Zn deposition in Zn- Fe al- loy anonymous codeposition can be confirmed as follows: Zn (OH)^(2-)_4 =Zn(OH)_2+2OH^-(Ⅰ) ;Zn(OH)_2 + e→Zn(OH)_(ad) +OH^-(rds) (Ⅱ) ; Zn (OH)_(ad)+e = Zn + OH^-(Ⅲ). Of which, step ( Ⅱ ) is determined as the rate- determining step of electrode reactions by the AC impedance of Zn (OH)_4^(2-) cathodic dis- charge.

关 键 词：ZN-FE合金电镀 异常共沉积 Zn(OH)4^2-阴极放电 交流阻抗 

分 类 号：TQ153.2[化学工程—电化学工业]