THE ELECTROLESS NICKEL PLATING PROCESS
This describes the plating of Nickel alloy deposits onto a suitable substrate using a chemical reduction process. These deposits may contain up to 13% Phosphorus by weight, or up to 5% by weight Boron. The electroless nickel plating process is sometimes simply called EN. Unlike electrolytically plated nickel coatings, they are produced without any externally applied electric current, onto catalytic metallic or catalyzed non-metallic substrates.
The coatings are applied to a wide variety of metallic and non-metallic substrates with both simple and complex geometries. Typical substrates include the electroless nickel plating of aluminum and steel. They are used to improve characteristics that are required for appearance, sophisticated engineering applications, magnetic plating and various harsh environments.
A large number of markets and industries benefit from our reliable, stable and environmentally advanced range of electroless nickel plating processes. These meet most global aerospace, automotive and military coating specifications.
AUTOMOTIVE
With the longer lives and greater reliability now required for automotive components, new applications are being developed, including the use of boron-nitride, a metal-ceramic composite coating that combines the strength and durability of electroless nickel coatings with the lubrication, and anti-frictional properties of hexagonal boron nitride (HBN)
Components treated with this coating include cylinder liners, differential pins, exhaust pipes and manifolds, lock pieces, pad holders for disc brakes / brake cylinders, piston rods, shock absorbers, steering assemblies and synchromesh gears. The use of the electroless nickel plating process in fuel applications is also increasing due to its excellent corrosion resistance to the new “bio” fuels increasingly being specified.
ELECTRONICS
For electronic components the coating is used for its combination of corrosion resistance and solderability. Other important considerations are the non-magnetic or magnetic coating properties, the uniform thickness and its consistent electrical, thermal and physical properties. These benefits are applied to consumer electronics, aerospace and military coatings.
Coaxial connectors, headers, housings and cases, heat sinks, diode cans, shutters, interlocks and memory disks and drums are among the many components presently plated with electroless nickel coatings.
CHEMICAL & PETROLEUM
The petroleum and chemical process industries are the largest users for corrosion protection. High nickel phosphorus of 25 to 75 μm (1 to 3 mils) thickness are commonly used to resist corrosion and erosion in aggressive brines, acids and gasses. Common applications include valves, chokes, blowout preventers, mud pumps, sucker rod and submergable pumps, pipe, heat exchangers and separators, packers, safety valves, production tubing, and all types of down hole tools.
FOOD
Food grade coatings must comply with all relevant regulation. The selection of the specific process depends on the usage and must be tested individually.
There is no general approval or recommendation of the electroless nickel plating process for food application. However due to its good corrosion and physical properties of electroless nickel plating of aluminum and steel substrates can be a good option for distinct applications.
MARINE
Plating aluminum with an electroless nickel coating is an excellent choice to withstand the harsh offshore environment. This corrosion resistant coating also offers outstanding wear resistance, therefore extending the life of components which receive constant handling and use such as pulleys and gears.
MATERIAL HANDLING
For packaging machinery and food handling equipment, the electroless nickel plating process is used because it provides and excellent corrosion and wear resistant coating which also provides an attractive finish to help ensure the cleanliness of the part.
Electroless nickel is used to handle such diverse products as sodium hydroxide, food grade acids and fish oils. Its uniform deposit is especially useful for hydraulic cylinders, worm feeds and extruders, shafts, chain belts and other close fitting parts. Common food handling applications include pneumatic canning machinery, hamburger molds and grills, bun warmers, baking pans, fryers and chocolate molds.
MINING
Mining environments are both very corrosive and abrasive. Mine waters are typically acidic and can cause high rates of attack of unprotected steel. In addition, the dust produced during mining can result in severe erosion.
The electroless nickel plating process provides coatingss which withstand these conditions with little attack. Common applications are hydraulic components, framing, cylinder heads for jetting pumps, pipeline connections and tubing, and mine engine components.
MILITARY COATINGS
Often written into specifications, MacDermid electroless nickel plating processes provide reliable solutions for reliable equipment. Extensively used for plating aluminum military coating applications comprise various requirements;
- Corrosion protection
- Uniformity
- Optical properties (i.e. low or high reflectivity)
- Lubricity
- Wear resistance
In most cases combinations are used to qualify electroless nickel coatings for military and defense.
MOLDS & DIES
The ability of electroless plating to provide a uniform deposit, even into deep recesses, helps to ensure that the finish on a mold will duplicate the original surface. The natural lubricity of the coating provides smooth flow during injection and quick and easy release of the part. Because of its high hardness at elevated temperatures, the electroless nickel coating minimizes erosion and abrasion of molds and dies and helps to extend their lives.
The coating also provides excellent protection against the corrosive fumes produced during molding such plastics as ABS, PVC, polycarbonate, acrylics and materials with thermoplastic additives. Similarly, electroless nickel plating has been found to provide a superior coating for zinc diecast dies and glass molds.
PRINTING & TEXTILE
The use of electroless nickel plating for cylinders and rolls used in the printing and textile industries has grown greatly during the past several years. The ability of the coating to deposit uniformly allows the cylinder to be machined to size, balanced and plated without subsequent finishing or grinding.
Typical plating thicknesses are 25 to 50 μm (1 to 2 mils). The life of this equipment is also greatly extended by this lubricious and wear resistant coating.
Other common textile applications include thread guides, fiber feeds, fabric knives, heddles, bobbins, shuttles, rapiers, ratchets, knitting needles and picks.
RAILROAD
Railroad and electroless nickel have a long history together.
For decades tanks containing corrosive media are plated with these corrosion resistant coatings. Another example are diesel engine shafts which benefit from the nickel coatings exceptional wear resistance and fretting characteristics.
In addition there are many more applications like unloading connections, trunions, bolts, etc.
WOOD & PAPER
Wood handling and pulp and paper equipment operate under conditions of severe corrosion and abrasion. The salt and organic acids present in woods can cause high rates of attack on common materials.
The electroless nickel plating process provides coatings with good protection against these conditions and are presently being used for knife holder cover plates and for abrading plates for wood cutting and chopping machines. Differential pins are also a large application area.
