Nickel used for engineering purposes is usually smooth and dark gray in appearance. Both bright and matt nickel have excellent corrosion resistance. Nickel is also used as a base plate for other metals such as gold and silver as it acts as a diffusion barrier preventing any form of substrate from migrating to the top coat.
Parts treated with a bright nickel finish will retain their surface appearance and brightness over time.
Engineered Nickel is used in non-decorative applications. Decorative bright nickel is used in the automotive industry, household and hand tools.
Nickel plating is the process of depositing nickel on metal parts. It can refer to:
Electroplated Nickel
Electroless Nickel
Nickel plating is a technique of electroplating a thin layer of nickel onto a metal object.
Electroless nickel plating is an autocatalytic reaction used to deposit a nickel coating on a substrate. Unlike electroplating, it is not necessary to pass an electric current through a solution to form a deposit. Electroless nickel has advantages over electroplating - no flux density and power issues, it provides a uniform deposit regardless of workpiece geometry, and with the appropriate pre-plating catalyst, it can be deposited on non-conductive surfaces.
Nickel layers can be applied to all commonly used pure metals and alloys. Substrates include:
Unalloyed and low alloyed steels
Copper and Copper Alloys
brass
Zinc and aluminum alloy
plastic
Before nickel plating a substrate, it needs to be free of
grease
Oil
scale
Oxide
Certain materials require special pretreatment prior to nickel plating, including:
zinc
Stainless steel
aluminum alloy
plastic
Nickel plating is deposited on the product by placing it in an aqueous nickel salt solution as a cathodic connection. Nickel anodes are used to complete the circuit and they are dissolved during the plating process to maintain the overall nickel metal concentration in the solution. Organic additives are added for even deposits and bright decorative coatings. Depending on the additives in the nickel plating bath, the surface finish can range from matte to semi-bright to bright. Common nickel plating baths are:
Sulfate
chloride
Fluoroborate
Sulfamate
The choice of bath depends on the desired properties of the deposit.
Nickel plating is often used as a base plating because it provides excellent interlayer adhesion and can level out pits or other imperfections in the base material. High-purity nickel is used in:
Electronics and Aerospace Applications
Chemical and Food Processing Equipment
anode and cathode
caustic evaporator
heat shield
