Electroless Nickel Plating was introduced in the 1950s as an alternative to conventional nickel electroplating. Instead of utilizing electrical current to deposit nickel metal, electroless nickel baths rely on a catalytic reduction chemical reaction to deposit a coating of a nickel phosphorous alloy.
Electroless Nickel Plating can evenly and effectively coat parts with threads, seams, and deep recesses. The plating solution moves freely over all surfaces, generating a consistent deposit thickness, even on parts with irregular shapes. Electroless Nickel chemistries can be adjusted to achieve varying levels of brightness. In many instances, the uniformity of the coating eliminates the need for post-plate grinding.
Electroless Nickel coatings are categorized as being either Low Phosphorous (2-5%), Mid Phosphorous (6-9%) or High Phosphorous (10-13%). As the phosphorous content in the deposit is varied, the coating properties changes as follows:
- Low Phosphorous Electroless Nickel provides the greatest “as deposited” hardness and corrosion resistance in alkaline environments.
- Mid Phosphorous Electroless Nickel provides consistently bright deposits and the best corrosion resistance across a wide range of environments
- High Phosphorous Electroless Nickel provides the best corrosion resistance in acidic environments
Post-treatment baking of all categories of electroless nickel improves adhesion, increases deposit hardness, and reduces the risk of hydrogen absorption.