双向脉冲无氰镀银工艺研究

Two-Direction Pulse Plating Process for Cyanide-Free Silver Plating

对无氰镀银工艺参数进行了优选,得出最佳双向脉冲参数如下:正向脉宽为1ms,占空比为10%,电流密度为0.8A/dm2,工作时间为100ms;反向脉宽为1ms,占空比为5%,电流密度为0.2A/dm2,工作时间为20ms,同时施加一与电场方向正交的磁场。在最佳工艺参数下得到的银镀层镜面光亮,与单向脉冲镀银和直流镀银相比,抗变色性和耐蚀性均显著提高,并通过扫描电镜观察了镀层的表面形貌。

The technological parameters for two-direction cyanide-free silver plating were optimized, and the optimal pulse parameters were established. Moreover, the morphologies of the resulting silver coatings were observed using a scanning electron microscope. As the results, the optimum two direction pulse parameters for the electrodeposition of bright silver coating were determined to be pulse width of 1 ms, positive duty cycle of 10%, average cathodic current density of 0.8 A/dm2, and work time of 100 ms in a positive pulse mode; while those in a negative pulse mode were determined to be pulse width of 1 ms, duty cycle of 5%, average cathodic current density of 0.2 A/dm2, and work time of 20 ms. Moreover, it was suggested to introduce a magnetic field perpendicular to the electric field in the negative pulse plating mode, and the silver coating deposited at the optimum parameters was mirror-like lucent and had much better anti-tarnishing capacity and corrosion resistance than the mono-direction pulse plated and direct current plated silver coatings.