Study on the Corrosion Resistance of Silver Coatings Prepared by ZHL-02 Replacement Plating and Electroplating

Abstract

Silver plating can be divided into replacement plating and electroplating.In order to compare the corrosion resistance and galvanic corrosion behavior of coatings prepared by these two methods，the corrosion resistance and galvanic corrosion behaviors of the ZHL-02 replacement plating and ZHL-02 electroplating coatings in cyanide-free silver plating process using 5，5-dimethylamide as the main complexing agent were analyzed by scanning electron microscopy，XRD，electrochemical workstation，Tafel curve and galvanic corrosion methods.Results showed that the replacement coating had better crystallization and more complete coverage，and its resistance to galvanic corrosion was slightly better than that of the electroplating coating under the same thickness.With the prolongation of replacement silver plating time，the self-corrosion rate of the coating gradually decreased.However，the replacement plating took a long time，and it was difficult to obtain a thickness of more than 1 μm，which limited its application to a certain extent.Compared with replacement plating，the plating speed of electroplating was much faster，the silver coating ＞2.4 μm could be obtained for 5 min.As the extension of electroplating time，larger particles would appear in the silver coating，forming defective structures such as tiny pores.When the electroplating silver times were 1，2，and 5 min，the corresponding self-corrosion rates were 7.15×10-3，5.30×10-3 and 4.27×10-3 mm/a respectively.Besides，when the electroplating time was extended from 1 min to 2 min and then to 5 min，the average galvanic corrosion rate of the coating decreased first and then increased.

Keywords

• cyanide-free silver plating|replacement plating|electroplating|corrosion resistance behavior