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Types Of Electroless nickel plating

  • Author:Coolidge
  • Source:www.diecastingpartsupplier.com
  • Release on:2018-09-19
Low-phosphorus electroless nickel

Low-phosphorus treatment is applied for deposits with hardness up to 60 on the Rockwell C scale. It offers a uniform thickness on inner and outer surfaces of complex shapes, which often eliminates the need for grinding after plating. It is also excellent for corrosion resistance in alkaline environments.[citation needed]
Medium-phosphorus electroless nickel

Medium-phosphorus electroless nickel (MPEN) has a phosphorus content of 4-10%, depending on its application. For decorative applications, 4–7% is considered medium-phosphorus; for industrial applications, 6–9%; and for electronics, 4–10%. The EN plating solution typically has eight components: nickel, a reducing agent, a complexing agent, stabilizers, buffers, brighteners, surfactants, and accelerators. Nickel sulfate is a typical nickel source, and sodium hypophosphite is a typical reducing agent. The complexing agent is necessary to increase phosphate solubility and to prevent the white-out phenomena by slowing the reaction. They are not co-deposited into the resulting alloy. Carboxylic acids or amines are typical complexing agents. Stabilizers, like lead, sulfur, or organic compounds, slow the reduction by co-deposition with the nickel. Most complexing agents act as buffers. Brighteners are mostly co-deposited with nickel, and usually are stabilizers, like cadmium or certain organic compounds. Surfactants lower the surface tension to reduce pitting and staining. Accelerators such as sulfur compounds are added to overcome the slow plating rate caused by complexing agents and usually are co-deposited, often discoloring the deposit.

MPEN plating deposits quickly and is very stable, with bright and semi-bright finishes. The processing often used for equipment in slurry disposal industries.[clarification needed] This is the most common type of electroless nickel applied.
High-phosphorus electroless nickel

High-phosphorus electroless nickel offers high corrosion resistance, making it ideal for industry standards requiring protection from highly corrosive acidic environments such as oil drilling and coal mining. With microhardness ranging up to 600 HV, this type ensures very little surface porosity where pit-free plating is required and is not prone to staining. Deposits are non-magnetic when phosphorus content is greater than 11.2%.[8]