Electroless nickel                                   

What is the electroless nickel :

Electroless nickel means in general terms nickel plating without current , but in chemical terms electroless nickel plating is an auto-catalytic reaction used to deposit a coating of nickel on a substrate. Electroless nickel plating requires no anodes, power supply or electrical connection of any kind. The process simply  mixing  some solutions, heating them to just off the boil, and then immersing the part to be plated. An auto catalytic electrochemical reaction takes place and the nickel is evenly deposited all over the part being plated. The thickness of the plate will depend on the duration of immersion. To stop the reaction, remove the part from the solution. 

 In Nickel  electroplating, it is  necessary to pass an electric current through the solution to form a only nickel  deposit and in electroless nickel deposit , deposit of coating will be phosphorous along with nickel .

Normally we do nickel  electroplating for decorative purpose but electroless nickel coating applied maximum for engineering and functional purpose like hardness , wear properties , corrosion resistance , lubricity, less porosity ,high temperature resistance  (upto 1200 degree centigrade) etc.

The demands of Electroless nickel coating come from oil and gas, printing, aerospace, electronics, medical and surgical parts, chemical processing , automotive industry etc .

Why we do electroless nickel:

Electroless nickel is costly compare to nickel electroplating but some people ask for electroless nickel coating instead of cheaply available nickel electroplating and they are ready to pay for that, why ?

ADVANTAGES :

1.       When we do Electroless nickel plating we get overall uniform thickness on the whole surface of  parts , here will be not any high or low  current density area  because here we don’t pass the current . which we can’t achieve in nickel electroplating .  

2.       In electroless nickel coating we can get the hardness of component upto 800 VHN .

3.       Can deposit the high thickness.

4.       Electroless nickel suitable for brazing and melting

Types of electroless nickel Process :

1.        Low  phosphorous process

2.        Medium  phosphorous  process

3.       High  phosphorous process

Electroless nickel process  is an auto – catalytic reaction at a particular temperature, Ph, Loading area and balanced chemicals . For a proper electroless nickel bath required following chemicals :

1.        Source of nickel ions

2.        Reducing agent

3.        Complexers,

4.        Neutralizers/buffers

5.        Stabilizers and  

6.        Brighteners.

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