Basics of electroplating

Electroplating is the process of depositing a layer of metal electrolytically on to a surface.The articles to be plated make the cathode of an electrolytic cell and a rod of the plating metal makes the anode.

Normally pure metals are used. E.g. Cu, Ni, Cr, Au, Ag, Pt, Zn

But there are exceptions such as Alloys (Cu-Zn, Ni-Cr) and metal with polymers or ceramics (metal-PTEF, metal- Ceramic)

Requirements for electroplating  

-Proper bonding between the plating material and the surface.

-Evenness of the plating.

-Cleanliness

-Leak holes must not be left.

-Texture: should have high brightness.

-Resistant to chemicals in the environment that can cause damage.

Essential parts of electroplating

Difference between Mⁿ⁺ and complex ions

Complex ions release metal ions slowly. Therefore its concentration is low. It’s important to obtain a smooth ending.

Additional electrolyte can be used to increase the conductivity of the system but it will not effect the solution’s ions. Sodium sulphate is an additional electrolyte.

Additives

Additives increase the quality of the electroplating.

-Brighteners: Saccaric acid, Thiourea

-Levelers:  Formaldehydes

-stress relievers: organic substances

-wetting agents: Sodium lauryl suphate

Factors affecting the quality of the electroplating

-Nature of the electrolyte

-Concentration of the electrolyte

-Purity of the electrolyte

-Nature of the additives

-Concentration of the additives (should be low)

-pH of the solution

-Temperature

-Current density

-Geometry of the electrode(whether it’s round or flat)

-Shape of the bath

-Flow conditions (stirring is good)

Hull cell
To study the quality of electroplating dependence on the current density.

Haring-Blum cell

To determine the throwing power of the electroplating process.