What is Electroplating & How does it work?
What is Electroplating ?
Electroplating is the process of plating a thin layer of other metals or alloys on certain metal surfaces by electrolysis. It is a process of attaching a metal film to the surface of a metal or other material by electrolysis. It can prevent metal oxidation (such as rust), improve wear resistance, electrical conductivity, light reflectivity, corrosion resistance (copper sulfate, etc.) and enhance aesthetics. The outer layers of many coins are also electroplated.
When electroplating, a plated metal or other insoluble material is used as the anode. The workpiece to be plated is used as a cathode. The cation of the plated metal is reduced on the surface of the workpiece to be plated to form a coating. In order to eliminate the interference of other cations, the plating layer is uniform and firm, and a solution containing a plating metal cation is required as a plating solution. In order to keep the concentration of the plated metal cations unchanged.
Why do we use electroplating?
Electroplating is generally done for two quite different reasons. Metals such as gold and silver are plated for decoration: it’s cheaper to have gold- or silver-plated jewelry than solid items made from these heavy, expensive, precious substances. Metals such as tin and zinc (which aren’t especially attractive to look at) are plated to give them a protective outer later. For example, food containers are often tin plated to make them resistant to corrosion, while many everyday items made from iron are plated with zinc (in a process called galvanization) for the same reason. Some forms of electroplating are both protective and decorative. Car fenders and “trim,” for example, were once widely made from tough steel plated with chromium to make them both attractively shiny and rust-resistant (inexpensive and naturally rustproof plastics are now more likely to be used on cars instead). Alloys such as brass and bronze can be plated too, by arranging for the electrolyte to contain salts of all the metals that need to be present in the alloy. Electroplating is also used for making duplicates of printing plates in a process calledelectrotyping and for electroforming (an alternative to casting objects from molten metals).
What products need electroplating?
- Sanitary ware and accessories
- Motorcycles, auto parts and steel furniture
- Locks, lighting and decorative hardware
- Plastic
Electroplating Applications
There are many aspects of electroplating applications, and the basic applications are three categories. That is, protective applications, decorative applications, and functional applications.
(1) Anti-corrosion. A metal layer is plated with a metal that is more resistant to corrosion than the metal itself. For example, a galvanized sheet is a layer of zinc plated on the iron plate. Improve the corrosion resistance of iron plates; there is also the plating of cadmium. It is also a widely used corrosion resistant coating. For example, the wheel rim of a bicycle is such a process; there is also nickel plating and the like.
(2) Decoration. Many of the metal parts we use every day look very bright. In fact, the surface is coated with a layer of nickel. Such as the bathroom faucets we bought, door handles and so on. For example, gold plating, some fake gold surface is coated with a layer of gold or copper.
(3) Performance. Some materials have no special properties, and plating on the material indicates the formation of a coating with this property. These materials have this special property. As we know, plastic is not electrically conductive, but some special requirements require plastic to conduct electricity. A special process is then used to coat the surface of the plastic with a layer of conductive metal. This plastic has electrical conductivity.
The purpose of electroplating is to plate a metal coating on the substrate. Change the surface properties or dimensions of the substrate. Electroplating enhances the corrosion resistance of metals. Increase hardness, prevent wear, improve electrical conductivity, smoothness, heat resistance and surface appearance.
The electroplated layer is more uniform than the hot dip layer and is generally thin, ranging from a few microns to tens of microns. By electroplating, decorative protective and various functional surface layers can be obtained on mechanical articles. It also repairs worn and machined workpieces.
There are different roles depending on various plating needs. Examples are as follows:
1. Copper plating: used as a primer to improve the adhesion of the plating layer and the ability to resist corrosion. (Copper is easily oxidized. After oxidation, patina is no longer conductive, so copper-plated products must be protected by copper.)
2. Nickel plating: base or appearance, improve corrosion resistance and wear resistance, (where chemical nickel is more resistant to chrome in modern processes). (Note that many electronic products, such as DIN heads and N heads, no longer use nickel as the base, mainly because nickel is magnetic, which affects the passive intermodulation in electrical performance)
3. Gold plating: Improve the conductive contact resistance and improve signal transmission. (Gold is the most stable and expensive.)
4. Palladium-plated nickel: Improve the conductive contact resistance, improve signal transmission, and wear resistance higher than gold.
5. Tin-plated lead: Improves the welding ability and is quickly replaced by other substitutes (because lead is mostly changed to bright tin and matte tin).
6. Silver plating: Improve the conductive contact resistance and improve signal transmission. (Silver has the best performance, is easy to oxidize, and is also conductive after oxidation)
how does it work?
Electroplating is the application of electrolytic cells in which a thin layer of metal is deposited onto an electrically conductive surface.
A cell consists of two electrodes (conductors), usually made of metal, which are held apart from one another. The electrodes are immersed in an electrolyte (a solution).
When an electric current is turned on, positive ions in the electrolyte move to the negatively charged electrode, called the cathode. Positive ions are atoms with one electron too few. When they reach the cathode, they combine with electrons and lose their positive charge.
At the same time, negatively charged ions move to the positive electrode, called the anode. Negatively charged ions are atoms with one electron too many. When they reach the positive anode, they transfer their electrons to it and lose their negative charge.
Material requirements
1–Most of the coating is a single metal or alloy. For example, titanium palladium, zinc, cadmium, gold or brass, bronze, etc.
2—There are dispersion layers, such as nickel-silicon carbide, nickel-fluorinated graphite.
3—There are cladding layers, such as a copper-nickel-chromium layer on steel, a silver-indium layer on steel, and the like.
4—In addition to iron-based cast iron, steel and stainless steel, electroplated base materials are non-ferrous metals, ABS plastics, polypropylene, polysulfone and phenolic plastics. However, plastics must undergo special activation and sensitization before plating.
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