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Transcript of Electroplating
Electroplating is a process where a metal is coated with a thin layer of another metal. A process used in electroplating is called electrodeposition. It is analogous to a galvanic cell acting in reverse. The part to be plated is the cathode of the circuit. In one technique, the anode is made of the metal to be plated on the part. Both components are immersed in an electrolyte containing one or more dissolved metal salts as well as other ions that permit the flow of electricity.
Electroplating is a process used to coat electrically conductive objects with a thin layer of metal using electrical currents.
Process called electrodisposition
Item requiring coating is placed in a container containing a solution of metal salts
Item is connected to an electrical circuit, negative side (cathode)
Both the anode and cathode are placed in the solution
Anode and cathode in the electroplating cell are connected to an external dc power supply
As the current travels through the circuit, metal ions in the solution pick up the extra ions at the item as the metal at the anode is oxidized to form cations with a positive charge
The produced cations travel to the cathode and bond with the anions.
This results in a thin layer of metal on the item
USES OF ELECTROPLATING General uses for electroplating are:
⇒Wear resistance (coating with a harder metal)
⇒Almost any hardware you buy whether it is wood screws or grade 12 carriage bolts they are most likely coated in a layer of zinc or nickel, depending on the application. This coating allows the hardware to resist corrosion from the elements.
⇒Home electronics: In today’s rapidly increasing demand for “new and improved” electronics such as TV’s, Ipods and laptops electroplating is a major part of this industry almost all connectors are plated with metals like silver and gold, to reduce corrosion and increase conductivity.
⇒Hydraulics (agricultural): Everywhere in the agricultural industry electroplating can be found, almost all agro equipment utilizes hydraulics to lift, push and pull. These hydraulic pistons have chromium plated piston rods, to reduce drag and increase wear resistance.
⇒Automotive industry: Electroplating is utilized by the automobile industry to produce shiny, eye catching parts on vehicles to help them sell and be attractive. But that’s not all many parts of a vehicles internal components are plated. Many engine cylinders and pistons can be titanium plated along with crank and camshafts, this is to reduce wear and prolong engine life
CHEMICAL PROCESS The equations for the electrochemical reactions at the anode and cathode are as follows:
Zn ---> Zn2+ + 2ecathode
Zn2+ + 2e- ---> Zn
takes electrons from the zinc
coating of the galvanized nail, and
moves them to the copper penny.
As the zinc atoms lose electrons,
they become positively charged
zinc ions, and move into the
solution. Meanwhile, at the copper
penny, the extra electrons
combine with the zinc ions in
solution, forming zinc metal atoms
which plate out on the penny.
Every time a metal ion plates out
at the cathode, another metal ion
goes into solution at the anode