Cyanide-free electroplating bath composition and process conditions

Plating bath composition and process conditions

Common zincate zinc plating bath composition and process conditions are shown in Table 2-1.

Note: Process 1 is the process of Wuhan Changjiang Chemical Plant; Process 2 is the process of Guangzhou Zhuhai Metal Protection Material Factory; Process 3 is the process of Wuhan Institute of Material Protection; Process 4 is the process of Hangzhou Dongfang Surface Technology Company; Process 5 is the process The process of Menhongzheng Chemical Co., Ltd.; Process 6 is the process of Shanghai Yongsheng Auxiliary Factory and Wuxi Qianqiao Auxiliary Factory; Process 7 is the process of Fuzhou Bada Surface Technology Institute; Process 8 is the process of Guangdong Dazhi Chemical Co., Ltd.; Process 9 is the process Process of Wuhan Fengfan Electroplating Technology Co., Ltd.; Process 10 is the process of Wuhan Institute of Material Protection; Process 11 is the process of Columbia, USA; Process 12 is the process of Atotech, USA.

The cyanide-free alkaline zinc plating process recommended above is more representative, and there are some better alkaline zinc plating processes and additives. Due to space limitations, I will not repeat them here. Readers can go through the experiment and go on their own choose.

(2) Basic principle and electrode reaction of alkaline zinc plating

Alkaline zincate zinc plating uses sodium hydroxide as a complexing agent for zinc ions, which can also act as a conductive and activating anode. The zinc ion in the zincate zinc plating solution is in the form of a monocomplex of sodium zincate, and the stability of the sodium zincate complex ion is not enough. To overcome this defect, it can be improved with sodium hydroxide The ratio of zinc oxide can be overcome. This ratio is called the M ratio, and its purpose is to increase the cathodic polarization of the plating solution. In the composition of the zincate zinc plating solution, the M ratio is required to be about 10, that is, lg zinc oxide is matched with about 10g sodium hydroxide, so as to improve the stability of the sodium zincate complex ion, thereby improving the bath’s performance Cathodic polarization, on this basis, some additives must be added to obtain a zinc coating with fine crystallinity, good coverage and brightness. The electrode reaction is as follows.