A comparative metal plating process to electroless nickel plating is electroplating, which utilizes an electrical current in order to achieve the same process that electroless plating is capable of achieving without electricity. Electroless nickel plating, also at times referred to as nickel coating, is a common industrial process and can be utilized in several other industries including: petroleum, in which it is used on essential components such as oil field valves and fuel rails; automotive, used to plate power transmission parts such as drive shafts; residential, used in coating kitchen utensils, door knobs, bathroom fixtures and more; and electronics, in order to plate electric components such as hard drive disks and printed circuit boards (PCBs). Although nickel is the most common material that is utilized in electroless plating processes, it is not the only type of material that can be electroless plated.
Additional materials that can be used electroless plating processes include: gold, silver, tin, zinc, copper, chrome, cadmium, palladium and rhodium. Of these material types and after nickel of course, the most commonly used in electroless plating processes are gold, silver, copper and palladium. In gold plating, a thin layer of gold is deposited on the surface of another metal, this most often occurs in electronics in order to provide other metal's with a corrosion-resistant and electrically conductive layer. Similarly used, silver plating is often utilized in the electronics industry as a less-expensive alternative to gold plating. However, silver-plated parts will not perform well in humid environments because of it does oxidize. Also used in the electronics industry, copper plating does not perform quite as well as either gold or silver, but is a much less-expensive option than either. In addition, copper has a higher conductivity than comparable other metals such as aluminum. Although palladium is not a common metal, in fact is a rather rare metal with a lustrous silvery-white color only discovered in 1803, one of its more common uses is that of electroless plating. Palladium works so well for electroless plating because it provides such excellent bath stability as well as a high corrosion resistance.
In addition to the more common metals used in electroless nickel plating, there are those that are widely used in electroplating, but not so widely used in electroless plating including tin, zinc, chrome, cadmium and rhodium. Electroless tin plating is also commonly utilized in the electronics industry, specifically for PCBs. Tin is typically alloyed with other metals such as lead or copper before it is used for electroless plating. Electroless zinc plating prevents oxidation of the plated metal. In addition, zinc is typically used in electroless barrel plating processes, which means that small parts are electroplated in large groups. Electroless chromium (EC) plating, or chrome plating, actually refers to an alloy of chromium rather than pure chromium, which can be very expensive and requires an electrical current in order to be plated. Electroless cadmium plating is not an incredibly common process because it is under some scrutiny because of some side-effects of the process with the metal that could potentially be hazardous to the environment. However, electroless cadmium plating remains widely used in the aerospace and military industries. Lastly, there is electroless rhodium plating, which is typically used on precious metals such as gold and silver for commercial applications such as jewelry.
The electroless plating process, which is also known as autocatalytic plating, is essentially a chemical reaction. In this chemical reaction, the metal being deposited onto the workpiece is immersed in an aqueous solution that is often referred to as a bath solution. Without using an external electrical power supply, the metal reacts instead as a result of the introduction of a reducing agent into the bath solution. The reducing agent, typically sodium hypophosphite, functions to release hydrogen and consequentially reacts with the metal ions of the material being deposited producing a negative surface charge and resulting in deposition. Contrastingly, the electroplating process uses an electrical current in order to reduce cations of a desired material from a solution instead of a chemical solution. When the reduction of cations occurs, a conductive object is coated with a thin layer of the typically metallic material. The electroplating process is primarily used for the deposition a layer of metal in order to provide the material being plated with a desirable property such as abrasion and wear resistance, corrosion protection, lubricity or aesthetic qualities that it would not otherwise have. Another application of electroplating is to build up the thickness of undersized parts.
Electroless Nickel Plating Types
- Cadmium plating is the process of depositing a thin, uniform layer of cadmium onto another substrate, such as a metal or plastic workpiece.
- is a finishing treatment that can be either bright chrome or hard chrome.
- Copper plating is the process of depositing a layer of copper onto a solid metal or plastic workpiece.
-
use hard particulate matter mixed with electroless nickel plating chemicals.
Silicon carbides and synthetic diamonds are common types of composite
materials.
- creates a slick, low friction surface.
- Electroless plating, also known as chemical or auto-catalytic plating, is a type of plating that does not use electricity.
-
is an alternate type of the coating/plating process. Using a low voltage
current, charged nickel compounds are attracted to a substrate's
oppositely-charged surface; in this fashion, nickel deposits are transferred
through a solution and onto the substrate.
- Gold plating involves the deposition of a thin layer of gold onto another substrate, typically a variety of metal parts.
-
has the best corrosion resistance of any electroless nickel plating
process. It is used in harsh environments, such as oil drilling and
coal mining.
- yields very good resistance to alkaline corrosive environments.
It also provides uniform thickness, so that grinding after the procedure
is unnecessary.
- is a popular form of nickel plating
that has been used over the years. It generates a nice uniform coating
and will not build up on the edges of the substrate.
- improve a product's corrosion and wear resistance.
- is the process of depositing a metal or metal alloy onto a surface.
-
are admired for their as-plated hardness, which is greater than that
of nickel-phosphorus platings. The melting point for N-B alloys is higher
than that of N-P, but chemical costs for nickel-boron baths can be up
to 10 times that of the nickel-phosphorus chemicals.
- is the process of coating an item with a nickel alloy to prevent oxidation.\
- Nickel plating is the process of depositing a thin layer of nickel onto another substrate, such as metal or plastic.
-
consist of nickel and boron or phosphorus. Other materials, such as
iron, cobalt and tungsten, are also included in poly alloys. Polly alloy
coatings allow maximum corrosion and high-temperature resistance, hardness
and magnetic or nonmagnetic qualities.
- Rhodium plating refers to the process of depositing a thin layer of the chemical element rhodium (Rh) onto a conductive metal surface.
- Silver plating is the process of coating another substrate with a thin layer of silver.
- Tin plating is the deposition of tin onto another material's surface, both ferrous
and non-ferrous, in order to provide increased protection from harsh
conditions.
- Zinc plating is an industrial process that utilizes either solely a chemical
reaction of a combination of a chemical reaction and an electrical
current in order to deposit a thin coating of zinc onto a metal part.
Electroless Nickel Plating Terms
-
The deformation or wearing away of a surface material due to frictional
forces and/or impact engendered by a nearby body or element.
- The loss of passivity
on the surface of a solid.
- The sticking together
or attractive force between two materials in contact. The adhesion that
electroless nickel provides to most metals is excellent.
- A solid compound consisting
of two or more metals fused together.
- A positively-charged
conductor that attracts nearby free electrons. Anodes are a uniformity
factor for the electroplating process, but not electroless plating.
- Metal that easily
oxidizes or dissolves, forming ions.
- A process that
is used to create an extremely bright surface on a metal.
- The quickened rate
of a chemical reaction due to a catalytic agent. Catalysts are often applied
to substrates to speed up the finishing procedure.
- The distance
from the top layer of the coating material to its substrate's outermost
surface. Common thicknesses for nickel deposits range from .0005 to .001
inches.
- A substance formed
by the chemical union of two or more elements.
- A metal's
capacity to transmit electric current.
- The deterioration
of a metal due to reaction with atmospheric elements. Nickel plating is
admired for its anti-corrosive qualities.
(http://www.iqsdirectory.com/deburring-equipment/)
- The removal of burrs and sharp edges on a metal by chemical, electrochemical
and mechanical processes.
- The ratio of a material's
mass to its volume. Nickel compounds used for coating purposes typically
have densities in the range of 7.7 gm/cm3 to 8.5 gm/cm3, depending on
the concentration of phosphorus.
- The ability of
a metal to withstand deformation before finally fracturing.
- The
ability of a material to resist the flow of electrical current.
- An alloyed
material that has a melting point lower than that of each individual element
alone.
- The resistance of
a material to deformations by indentation. For electroless nickel plating,
common hardness values range from 44 HRC to 59 HRC.
- The act of submerging
a product. Substrates are immersed into baths containing electroless nickel
plating chemicals.
- A charged atom or molecule.
- A reaction in which
electrons are removed from a reactant, usually because of the addition
of oxygen.
- A decrease in the
corrosion rate of metal, which results from the application of a protective
film such as electroless nickel plating.
- The material that
is being coated or plated.
- The maximum
amount of tensile force that can be applied to a material before it is
broken apart. Electroless nickel plating has comparable tensile strength
to many hardened steels.
- The surface features
of a material. Substrate topography affects coating appearances for many
metal products.
