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===7.1.1 Electroplating (or Galvanic Deposition)===
For electroplating of metals, especially precious metals, water based solutions
(electrolytes) are used which contain the metals to be deposited as ions (i.e.
dissolved metal salts). An electric field between the anode and the work pieces
as the cathode forces the positively charged metal ions to move to the cathode
where they give up their charge and deposit themselves as metal on the surface
of the work piece.
Depending on the application, for electric and electronic or decorative end use,
different electrolytic bath solutions (electrolytes) are used. The electroplating
equipment used for precious metal plating and its complexity varies widely
depending on the process technologies employed.
Electroplating processes are encompassing besides the pure metal deposition
also preparative and post treatments of the goods to be coated. An important
parameter for creating strongly adhering deposits is the surface of the goods to
be metallic clean without oily or oxide film residues. This is achieved through
various pre-treatment processes specifically developed for the types of material
and surface conditions of the goods to be plated.
In the following segments electrolytes – both precious and non-precious – as
well as the most widely used electroplating processes are described.
===7.1.1.1 Electroplating Solutions – Electrolytes===
The actual metal deposition occurs in the electrolytic solution which contains
the plating material as metal ions. Besides this basic ingredient, the electrolytes
contain additional components depending on the processes used, such as for
example conduction salts, brighteners, and organic additives which are codeposited
into the coatings, influencing the final properties of the electroplating
deposit.