What Does Electroless Nickel Plating (EN Plating) Mean?
Electroless nickel (EN) plating is an auto-catalytic reaction used to deposit a coating of nickel on a substrate such as metal or plastic. It provides wear resistance, hardness and corrosion protection of the substrate. It is also commonly used as a coating for electronic printed circuit boards, typically with an overlay of gold to prevent corrosion.
Electroless nickel plating has several advantages over electroplating. Free from flux density and power supply issues, it provides an even deposit regardless of workpiece geometry, and with the proper pre-plate catalyst, can deposit on non-conductive surfaces.
Corrosionpedia Explains Electroless Nickel Plating (EN Plating)
Electroless nickel plating is a chemical reduction method that depends upon the catalytic reduction technique of nickel ions in an aqueous solution and the subsequent deposition of nickel metal on the substrate without the use of electrical energy. Electroless nickel plating can be applied to both ferrous and non-ferrous surfaces of any geometry.
This electroless process greatly improves the object's resistance to galling and leaves a predictable, uniform nickel coating on high-precision parts. Electroless nickel plating is often less porous than electroplated nickel and hard chrome, provides barrier protection to steel, and can also be applied with little or no compressive stress, thus making it gentle in application.
This process provides a wide range of thickness and volume of the plating on metallic surfaces, and can easily fill recesses or pits in the metal's surface, resulting in a uniform surface finish. This allows for a wide variety of industrial parts to be plated, such as:
- Oil field valves
- Drive shafts
- Electrical/mechanical tools
- Engineering equipment
The most common variants of electroless nickel plating are:
- Composite electroless nickel plating, in which silicon carbide (SiC) particles are co-deposited with the nickel to enhance its strength and wear resistance
- Duplex electroless nickel plating, where an undercoat containing 14% phosphorus is used with a top coat of 5% phosphorus
EN techniques are also used to manufacture composite coatings by suspending powder in the bath.