January 29, 2011

Silver Plating

Silver plating often applied for decorative finished for less demanding applications on electronics, silver is often used as a cheaper replacement for gold, as the best corrode resistant materials. Although silver have better conductor properties than gold it does oxidize and so gold is better of contacts.

Care should be used for parts exposed to high humidity environments. Silver rather stand to porous but if this layer is porous or contains cracks, the underlying copper undergoes rapid because of galvanic corrosion, flacking off the plating and exposing the copper itself, a process known as red plague.

Silver plate was to provide a cheaper version of items that might otherwise be made of silver, including cutlery and candlesticks. The method for silver coating on metal usually use silver electroplating, but in glass industry other method to create a mirror use Tollen's Test. Using Tollens method, the final reaction can occur by placing Tollen's Reagent in a glass and then adding Glucose/Dextrose and shaking the bottle to form the reactions as follows:

AgNO3 + KOH ---> AgOH + KNO3
AgOH + 2 NH3 ---> [Ag(NH3)2]1+ + [OH]-1 
[Ag(NH 32]1+ [OH]-1  + Aldhehyde -----> Ag + 2 NH3 + H2O