What is the definition of free cyanide in cyanide plating solution for electric heating tubes?
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What is the definition of free cyanide in cyanide plating solution for electric heating tubes?
Answer: In cyanide plating solution, excess cyanide that is not bound to the salt is called free cyanide. For example, the free cyanide in cyanide copper plating solution is the excess cyanide formed outside of [Cu (CN) 3]=complex ions.
13. In cyanide copper plating, the anode undergoes passivation, poor dissolution, and why does the content of free cyanide increase?
Answer: During cyanide copper plating, there is poor anodic dissolution. Although some cyanide ions are oxidized and consumed on the anode, more free cyanide ions are generated on the cathode due to the discharge of copper cyanide complex ions, resulting in an increase in the content of free cyanide in the plating solution.
14. What effect does the anode material of acidic bright copper plating have on the quality of the coating?
Answer: In the acidic bright copper plating process, if electrolytic copper anodes are used, it is easy to produce copper powder, causing rough coating, and the consumption of brighteners is fast. Therefore, copper anodes containing a small amount of phosphorus (0.1-0.3%) should be used, which can significantly reduce copper powder. However, if copper anodes with high phosphorus content are used, their dissolution performance will deteriorate, resulting in a decrease in copper content in the plating solution.
15. In nickel plating solution, when the anode area decreases and the anode current density increases, does the pH value of the solution increase or decrease?
Answer: The pH value of the solution decreases. This is because the anode decreases, the current density increases, and the anode undergoes passivation without dissolution. After passivation, oxygen is released, and H+in the solution increases, resulting in an increase in acidity and a decrease in pH.
What should be added to promote anodic dissolution in nickel plating solution? Is it okay to add a large amount of boric acid?
Answer: To promote the dissolution of nickel anodes, an appropriate amount of chloride ions should be added. Boric acid did not promote the anodic dissolution of nickel.
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