A kind of cyanide-free silver plating solution and silver coating and preparation method thereof

Abstract

The invention discloses a cyanide-free silver plating solution, a silver plating layer and a preparation method thereof. The cyanide-free silver plating solution of the present invention comprises silver nitrate, multiple complexing agent, conductive salt, buffering agent and additive; Described multiple complexing agent is main complexing agent with triethylenetetramine or / and its soluble salt, with One or more of triethylenetetraaminehexaacetic acid or triethylenetetraaminehexaacetic acid salt, ethylenediaminetetraacetic acid or ethylenediaminetetraacetic acid salt, citric acid or citrate are auxiliary complexing agents; The concentration of silver nitrate is 0.1-0.7mol / L, the concentration ratio of main complexing agent and silver nitrate is 1-6:1, the concentration of auxiliary complexing agent is 0.05-1mol / L, and the concentration of conductive salt is 0.2- 1.2mol / L, the buffering agent is used to adjust the pH value of the cyanide-free silver plating solution to be 2-7; the additive is a mixture of rare earth salt, rare earth salt and benzotriazole or / and surfactant, the concentration of the additive 0.001‑0.035mol / L. The cyanide-free silver plating solution of the invention has good stability, and the prepared cyanide-free silver plating layer has a compact structure.

Description

technical field [0001] The invention relates to the technical field of surface treatment, in particular to a cyanide-free silver plating solution, a silver plating layer and a preparation method thereof. Background technique [0002] Silver plating is widely used in the power electronics industry and aerospace industry because of its excellent conductivity and weldability, and is also widely used as a decorative coating in tableware, jewelry and other crafts and artworks. The highly toxic cyanide silver plating technology has a history of 180 years since the British Elkington brothers first applied for a patent in 1840. However, the cyanide silver plating process is still widely used in industrial production. Cyanide can form with silver ions Stable metal complexes are the key factor. [0003] Researchers have conducted in-depth and long-term research on cyanide-free silver plating technology, developed a series of cyanide-free silver plating processes, and promoted the pro...

AI Technical Summary

Problems solved by technology

In terms of succinimide silver plating, Wang Zongli and others conducted research on succinimide silver plating in 1979, using succinimide and Ag + Complexation stability constant K 稳 up to 10 9.54 advantages; CN109504989A disclosed in 2018 a bright brush plating silver plating solution with succinimide as the main complexing agent and its preparation process, but Yang Fangzu et al. (CN107841771A) believed that succinimide plating The solution is not so stable, and the resulting coating is prone to yellowing and discoloration when it meets water. Wang Zongli and others also reported that the disadvantage of the succinimide silver plating process is that the coating is prone to yellowing after being left on hold.