In this topic, you study the definition, process & diagram of electroplating.
Electroplating is a process by which a metal is deposited on any other metal by passing current in the electrolyte. The basic principle is the electrolysis, i.e. the decomposition of the electrolyte used. The material to be deposited is made as anode and where deposited as cathode.
For electroplating the d.c. low voltage is used upto 25 V or so. The d.c. can be taken from the d.c. generator or battery or rectifier. The current rating depends upon the area to be plated. The current is also different for different metals and Cathode.
The electrolyte is a solution of the metal element which is do be deposited or plated; for example, for silver plating the solution is AgN01;
Fig. 9.2. Electroplating.
Process of electroplating. Figure 9.2 shows a simple arrangement of silver plating. The solution is the silver nitrate (AgN03). There are two electrodes, one Ag plate which is anode and the article to be plated as cathode. A variable resistance is connected in the circuit to control the voltage and to limit the current. As the current is passed AgN01 decomposes into its ions
AgN03 -5 Ag• + NO,-
The Ag4 being positively charged is attracted towards the cathode where the object to be plated is kept. So the Ag particles are collected layerwise forming a uniform layer of silver particles. The anode is the Ag electrode so that the gravity of the solution is maintained.