Different nickel-plating chemicals incorporated into the process deliver anything from a semi-bright and fully bright cosmetic effect, to matte, pearl, or satin finishes. To transfer nickel onto the surface of a product properly, a negative charge must be applied to the base material. To achieve this, the product is typically attached to a rectifier, battery or other power supply via a conductive wire.
Once attached, a rod made of nickel is connected in a similar fashion to the positive side of the rectifier or power source. Once the initial steps have been completed, the base material is submerged in a solution that features a salt with a chemical makeup, including the electroplating metal.
With electro nickel plating, this solution consists of water and nickel chloride salt. Due to the electric current present in the solution, the nickel chloride salt dissociates to negative chloride ions and positive nickel cat-ions. The negative charge of the base metal then attracts the positive nickel ions, while the positive charge of the nickel rod attracts the negative chloride anions. Through this chemical reaction, the nickel in the rod oxidizes and dissolves into the solution.
From here, the oxidized nickel is attracted to the base material, and subsequently coats the product. Current density directly determines the deposition rate of nickel to the base material—specifically, the higher the current density, the quicker the deposition rate.
Current density, however, also affects plating adherence and plating quality, with higher current density levels delivering poorer results. This is opposed to electro nickel plating, which often results in thicker deposit buildups around the edges and corners of the base material. The precise microstructure of the nickel-phosphorous coating is largely due to the specific alloy used in the solution. Commercial baths typically employ solutions that consist of between one and fourteen percent phosphorous.
Solutions including less than seven percent phosphorous are low-level solutions and create a microcrystalline structure, with each grain ranging between two and six nm. Solutions with larger amounts of phosphorous have an amorphous. This results in a mixture of amorphous and microcrystalline phases at moderate phosphorous levels seven to ten percent , and a complete amorphous phase in solutions at or above a ten percent phosphorous level.
Electroless nickel has a unique melting range that is dependent on the level of phosphorous in the specific compound. In general, the melting point decreases as phosphorous levels increase.
Pure nickel melts at 1,degrees Celsius, and high phosphorous electroless nickel melts at approximately degrees Celsius. An inverse relationship is also present in the magnetism and solderability of electroless nickel plating. Lower phosphorous levels yield improved magnetism and solderability. Different phosphorous levels in electroless nickel plating serve different applications.
Benefits for each level vary: Prior to EN plating, it is important to consider the effects of residual stress. Factors affecting localized residual stresses in the base product include exposure to manufacturing processes welding, machining, etc. Also, metals hardened through heat treatment or other measures will likely require pretreatment stress relief.
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Before plating, the surface of the material is cleaned by applying a series of chemicals. Uniform deposit thickness regardless of part geometry Reduced porosity provides superior corrosion resistance Improved hardness Solderability of low phosphorous and electroless nickel boron alloys Ability to create compressive or non-existent stress Reduced hydrogen absorption For most applications, the uniformity of electroless nickel plating is the main reason manufacturers use the process. Electro Coatings Give Us a Call After applying each pretreatment chemical, the surface is rinsed two to three times with water to completely remove the chemicals. Most complexing agents act as buffers. Through this chemical reaction, the nickel in the rod oxidizes and dissolves into the solution. Its use in the automotive industry for wear resistance has increased significantly.
Plating Process of Electroless Nickel Electroless nickel plating has long been a preferred solution for improved hardness, corrosion resistance and friction resistance in industrial applications. Electro-Plating For a more detailed analysis of the differences between the electroless plating and electro-plating metal coating processes, visit Electroless Plating vs.
Provides barrier corrosion protection to steel, and can be applied with zero or little compressive stress making it gentle in application. No electricity required, can be completed with less equipment and fewer coats than electroplating to create a strong, high-quality finish.
Electroless nickel plating (EN) is an auto-catalytic reaction that deposits an even layer of nickel-phosphorus or nickel-boron alloy on the surface of a solid. Nickel plating may refer to: Nickel electroplating, a technique of electroplating a thin layer of nickel onto a metal object; Electroless nickel plating.
Provides a large flexibility of thickness and volume of the plating on metal surfaces and can easily fill recesses or pits in the metal surface. A wider variety of industrial parts to be finished with a uniform surface.