Silver Passivation in electroplating

[Jandette]

hi

I´m working on a personal project, surfing through the internet but I can´t get it done and would really appreciate any help.

 

I´ve been trying to electroplate silver onto copper but I have failed because of the passivation on the silver (cathode). The best dissolution for this, I´ve found on the internet, is with AgCl (precipitate) and HNO3 (aq) as a result of mixing AgNO3 (four grams dissolved in 100 ml of soft water) and HCl (300 ml with a concentration of 28%), with the current of a 9 volt battery (the square ones). I´m quite certain that the nitric acid should stop the oxide layer on the silver but this isn´t happening. How can I stop the passivation? Should I add another compound or the problem is in the current intensity?

 

I cleaned both pieces with specific commercial products to remove oxides and grease. Besides I treated the copper with sandpaper to make room for the silver layer.

 

Thanks a lot.

 

[Sensei]

The best dissolution for this, I´ve found on the internet, is with AgCl (precipitate) and HNO3 (aq) as a result of mixing AgNO3 (four grams dissolved in 100 ml of soft water) and HCl (300 ml with a concentration of 28%), with the current of a 9 volt battery (the square ones).

But you didn't use all 300 mL at once of course.. ?

It's approximately 100x more in moles than 4 g of AgNO3..

Edited September 18, 2015 by Sensei

[John Cuthber]

But you didn't use all 300 mL at once of course.. ?

It's approximately 100x more in moles than 4 g of AgNO3..

Unless they did because they want some of the silver in solution as the complex [AgCl2]^- ion.

Having said that, it seems an odd choice to me.

 

Jandette, where did you get the recipe from?

Are you able to measure the current flowing?

[Jandette]

Oh, nope. I see my mistake now. The current is 0.19 A. Theoretically speaking, with the right molar concentration, should it work? is there a better (simpler and safer) way?

 

Tanks a lot again