脉冲无氰镀银及镀层抗变色性能的研究

Pulse non-cyanide silver electroplating and anti-tarnish property of silver deposits

采用赫尔槽试验筛选出一种阴离子表面活性剂及含氮杂环化合物作为脉冲无氰镀银的添加剂,并初步确定了无氰镀银的工艺条件及脉冲条件。通过正交试验进一步优化脉冲条件及镀银添加剂含量分别为:脉宽1ms、占空比10%、平均电流密度0 6A/dm2、阴离子表面活性剂及含氮杂环化合物含量分别为12mg/L、110mg/L。测定了该镀银层的耐蚀性、抗变色性能及与基体的结合力,并用扫描电镜对其微观形貌进行了观察。结果表明,脉冲无氰镀银层的抗变色性能优于直流无氰镀银层;光亮镍打底后再脉冲无氰镀银,可获得更加光亮、结晶细致的镀银层,且抗变色性能及耐蚀性均增强。

By Hull cell test, a kind of anion surfactant and nitrogen heterocyclic compound was chosen as a additive for pulse non-cyanide silver electroplating. And the process conditions of the silver plating and the pulse conditions were preliminarily ascertained. The pulse conditions and additive content were optimized by orthogonal test as follows: pulse width of 1 ms, positive duty cycle of 10%, average current density of 0.6 A/dm^2, 12 mg/L of negative ion surfactant, and 110 mg/L of anion heterocyclic compound. The corrosion resistance, anti-tarnish property and adhesion of the deposits were tested, and the micro-morphology of the deposits was studied with SEM. The results show that the non-cyanide silves deposits obtained with pulse current have better anti-tarnish property than those obtained with direct current. With bright nickel strike plating before pulse non-cyanide silver plating, brighter and finer silver coatings with stronger anti-tarnish property and corrosion resistance can be obtained.