Several types of electroless plating exist, with electroless nickel plating being the most common by far. Electroless plating is different than electroplating because it is not necessary to pas an electric current through the solution to form a deposit. Electroless nickel plating is a process or technique where a layer of nickel-phosphorous (usually around 12-10%) or nickel-boron alloy is deposited onto a solid workpiece by a controlled chemical reduction. The workpiece is usually made of metal or plastic. The technique used is an auto-catalytic chemical technique which basically means that in the chemical reaction at least of the reactants is a product.
The reason electroless nickel coating is the most common is due to the fact that electroless nickel has the unusual quality of being amorphous (without clearly defined shape or form), and not crystalline (having the structure and form of crystal). When a product is coated by electroless nickel plating, it possesses high hardness, natural lubricity and good wear and abrasion resistance. It helps to prevent corrosion and wear.
Common applications for electroless nickel plating include fasteners, pipes and valves, rotors, drive shafts, paper handling equipment, fuel rails, optical surfaces for diamond turning, door knobs, kitchen utensils, bathroom fixtures, electrical/mechanical tools and office equipment. Most components used for engineering purposes have a thickness between 50-100 micrometers. When more rough surfaces are encountered, greater thickness is usually required. Electroless nickel plating extend the longevity of parts, large and small, which are exposed to harsh environments. Parts that are treated by electroless nickel plating are highly resistant to rust and other environmental factors.
There are three types of electroless nickel plating. They include low phosphorous, medium phosphorous, and high phosphorous electroless nickel. Each type of electroless nickel has particular advantages depending on the application and type of nickel alloy. Electroless nickel plating is most commonly used in engineering coating applications.