page_title: Electroless nickel-phosphorus plating
section_title: Applications
hierarchical_section_title: Electroless nickel-phosphorus plating / Applications
caption_attribution_description: Français&#160;: photos electroless nickel
context_page_description: Electroless nickel-phosphorus plating is a chemical process that deposits an even layer of nickel-phosphorus alloy on the surface of a solid substrate, like metal or plastic. The process involves dipping the substrate in a water solution containing nickel salt and a phosphorus-containing reducing agent, usually a hypophosphite salt. It is the most common version of electroless nickel plating and is often referred just by that name. A similar process uses a borohydride reducing agent, yielding a nickel-boron coating instead.
  Unlike electroplating, electroless plating processes in general do not require passing an electric current through the bath and the substrate; the reduction of the metal cations in solution to metallic is achieved by purely chemical means, through an autocatalytic reaction. Thus electroless plating creates an even layer of metal regardless of the geometry of the surface – in contrast to electroplating which suffers from uneven current density due to the effect of subtrate shape on the electric resistance of the bath and therefore on the current distribution within it. Moreover, electroless plating can be applied to non-conductive surfaces.
context_section_description: Electroless nickel-phosphorus is used when wear resistance, hardness and corrosion protection are required. Applications include oilfield 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.
  Due to the high hardness of the coating, it can be used to salvage worn parts. Coatings of 25 to 100 micrometers can be applied and machined back to the final dimensions. Its uniform deposition profile means it can be applied to complex components not readily suited to other hard-wearing coatings like hard chromium.
  It is also used extensively in the manufacture of hard disk drives, as a way of providing an atomically smooth coating to the aluminium disks. The magnetic layers are then deposited on top of this film, usually by sputtering and finishing with protective carbon and lubrication layers.
  Its use in the automotive industry for wear resistance has increased significantly. However, it is important to recognize that only End of Life Vehicles Directive or RoHS compliant process types (free from heavy metal stabilizers) may be used for these applications.
caption: Electroless nickel coating is often used to smooth the platters of hard disk drives.
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