3.C] What is electroplating? Explain the electroplating of chromium
Answer:-
Electroplating is the process in which base metal is uniformly coated with suitable metal by electrodeposition.
Electroplating of chromium is carried out on the pretreated Ni or Cu articles.
Decorative Chromium Coatings: Decorative chromium coating is the coating of thin layer of chromium with thickness of 0.25 to 0.75µm. thicker deposits look very dull.
Hard Chromium coating: Deposition of chromium with a thickness of 0.005 to 0.75mm is referred as hard chromium coating.
In chromium plating sulfate ions act as catalysts. In CrO3 bath solution, Cr is in Cr6+ state.
This is converted into Cr3+ by a complex anodic reaction which is then coated as Cr on
the cathode surface.