Electrolytic nickel plating is an important coating process for a wide range of applications. It provides corrosion resistance, and high solderability and helps prevent 'whiskers' that can create short circuits.
During the electrolytic nickel plating process, an external electrical current is used to drive deposition. This creates a mixture of high- and low-current areas on the part surface. This results in an uneven coating layer.
Electroless nickel plating can create an extremely hard and durable surface, which is ideal for equipment that will be exposed to harsh environments. It also offers a smooth, consistent finish that can be customized from matte to shiny.
The surface is also resistant to rust, which makes it a popular choice for applications such as home electronics, where aesthetics are important. It is also chemically resistant and reduces friction, making it an excellent choice for aerospace materials.
However, there are some drawbacks to electroless nickel plating that can affect dimensional tolerances. Parts that have complex geometries or one-way holes may develop dog boning if they are not uniformly plated.
Typically, these issues can be addressed through post-plating heat treatment, which can increase the hardness of an ENP deposit by up to 70 Rc. It can also help improve the ductility of the nickel coating, making it less likely to crack or break under stress.
Electrolytic nickel plating uses a chemical bath to coat parts with a thin layer of nickel. It is used for a variety of applications, including medical and military equipment, aerospace parts and oil and gas equipment.
The chemical resistance of electrolytic nickel coatings depends on the type of solution that is used and the process parameters, such as current density and temperature. It is important to use a quality nickel sulfamate solution that contains a large concentration of sulfate to ensure optimal deposit rates.
When applying electrolytic nickel coatings, it is essential to clean the base material thoroughly before plating. This helps prevent oxidation, which can cause damage to the surface.
A medium phosphorus electroless nickel coating is often used to provide bright appearance and magnetic properties, as well as moderate corrosion resistance. The phosphorus content in the solution is typically between 5% and 9%.
Resistance to Corrosion
Electrolytic nickel plating - the most common type of nickel coating - relies on an electrical current to chemically reduce nickel ions. These cations then attach to the surface of a metal substrate, which can vary in composition, and provide a layer of pure nickel.
In comparison, electroless nickel plating - or autocatalytic coating - does not require an electrical current to start the deposition process. Instead, an electroless formula is a chemical reducing agent (usually phosphorous) that allows a technician to coat the component without having to use an additional electroplating process.
This allows ENP to offer corrosion resistance with greater wear- and lubricity compared to electrolytic nickel plating. It also provides more uniform deposit density that is often not achieved with traditional electrolytic processes. This can result in a greater coating thickness for many complex shapes and can help save cost in the long run.
Electrolytic nickel plating adds a layer of bright and durable nickel to the surface of your product. It can also increase corrosion resistance and protect your product from damage, thereby extending its lifespan.
You’ll find electroless nickel plating on many household and industrial products, from kitchen utensils to bathroom fixtures and machinery. It’s a cost-effective and versatile coating solution, providing aesthetics and durability.
Unlike electrolytic nickel plating, which uses an external current source, electroless nickel plating relies on a chemical reduction process to produce the coating. This autocatalytic reduction is triggered by reducing agents, such as sodium hypophosphite, which are placed in the nickel plating bath.