Electroless nickel (also indicated as autocatalytic nickel) coatings are alloys of nickel and phosphorous produced by autocatalytic chemical reduction with a reducer. They have multifunctional properties such as hardness, heat hardenability, abrasion, wear and corrosion resistance, magnetics, electrical conductivity, provide diffusion barrier and solderability. They are also used for repair of worn or wrong machined parts (ASTM B733).
To get a pore-free surface the coating thickness shall be at least 25 microns. We can plate a maximum layer thickness of 50 microns. With a thermal post treatment the coating can be hardened up to a factor 1.5 compared to “as plated” electroless Nickel, which is already almost twice the hardness of electroplated Nickel. Depending on the type of bath the phosphorous-content varies from 8 – 13 %. Higher phosphorus-content gives higher corrosion- and chemical resistance of the coating, but also results in less magnetism and less solderability of the coating.
Application of electroless nickel (EN) is especially suitable for complex shaped products because coating thickness can be controlled within ± 2 microns accuracy. This cannot be achieved in any electroplating process due to thickness variation resulting from non-uniform current distribution.
|Properties of electroless nickel|
|Content Ni||87 - 92,5||%|
|Content P (mid-phos NiP-coatings,standard used on aluminium)||7,5 - 10||%|
|Content P (high-phos NiP-coatings,standard used on steel)||10 - 13||%|
|Density (mid-Phos / high-Phos)||8,1 / 7,8||± 0,2 g/cm3|
|Melting point||850 - 880||°C|
|Electrical resistance||50 - 100||µΩ/cm|
|Magnetism mid-Phos / high-Phos||Slight / Not|
|Solderability mid-Phos / high-Phos||Good / Poor|
|Hardness as plated||500 - 600||HV|
|Hardness after thermal treatment (standard 16 hours 280 °C)||900 - 1000||HV|
Base materials for electroless nickel plating: steel and aluminium.
|Maximum product dimensions:|
|LxWxH = 1300 x 300 x 900 mm|