Metal Plating: The Complete Guide

Before starting your next metal plating project, read this guide. It covers all the critical details about metal plating process. So, if you want to be a metal plating expert, read this guide.

What Is Metal Plating?

It is the process done by electroplating to coat metals and depositing them on the stratum, forming a thin layer of metal over the stratum. Metal plating is usually done by inserting the metal into an acid solution with a cathode and anode electric current.

History Of Metal Plating

Metal plating was discovered in 1805 when a wire was linked between a melting gold solution that acted as an anode and a battery as a cathode. The metal part was then connected to the wire, thus enabling the gold to become in contact with it, producing a shiny gold coating. The process later became very popular and was used for coating printing plates in copper solution, potassium cyanide, silver, and gold. The popularity of the method continued to grow. In the 1940s, potassium cyanide solutions were replaced with acid baths, and ever since, the technique has been depended on by many industries.

History Of Metal Plating
Zinc Plating

Zinc Plating

The zinc plating technique is used for light switch plates, screws, and small parts that can be exposed in inner or mild corrosive conditions. It is usually dull grey and thin with a matte finish; hence, it reacts differently to the agents added to the plating bath. The zinc is applied as an electrode in cyanide, alkaline non-cyanide, or acid chloride salt solution; hence post-plating treatments may be used to passivate the zinc surface. Normally, the parts are then loaded into a drum and inserted into the plating solution after alkaline cleaning, and different agents may be added to the answer to add luster.

Cadmium Plating

It is a coating that can be applied on materials like steel, copper, Aluminum, and iron since it is a sacrificial coating; thus, it corrodes effectively when used over the materials. Cadmium plating has a low electrical resistance and good conductivity; hence it can be used with a wide range of base metals. Its high bath efficiency makes it an excellent solution to coat weak parts and complex geometries; thus, it works best as a paint base. The coating is soft, ductile, and malleable; hence it corrodes first even when scratched since it provides galvanic protection for base metals.

Cadmium Plating
Gold Plating

Gold Plating

It is the coating of gold on the surface of another metal that has a conductive surface after it is cleaned, polished, and sandblasted. The process is commonly used for jewelry, electronics for corrosion resistance, and a conductive layer on the copper for electrical connectors. Additionally, the plating is preferred because of its low cost with the same aesthetic effect; hence it can be re-plated if the layer is damaged.

Nickel Plating

It is an undercoat plating of applying a thin layer of nickel onto a metal part to provide wear resistance and corrosion resistance and add brightness to the metal. The method is widely used to provide good adhesion and enhance the products’ utility, value and appeal. It also improves their flexibility, performance and appearance. There are three type of nickel plating;

Electroless nickel plating – Effective for even coating and can deposit on surface which are nonconductive hence ideal for preventing corrosion and wear.

Dull nickel plating – The coating creates thickness and useful for dimensional correction thus it is hard wearing and malleable.

Bright nickel plating – It offers good conductivity but it is not corrosion resistant as other nickel plating.

Nickel Plating
Tin Plating

Tin Plating

Tin plating is commonly used in metal cans for storing food since the cans are coated with a thin layer of tin. It improves appearance, performance, and durability since it is used to prepare metal for use in construction like metal roofing. The plating prevents the metal-like steel from corrosion and flexibility, making it easier to weld to another surface.

Chromium Plating

A process by which, a metal object is immersed into a thin layer of chromium hence providing corrosion resistance or increasing surface hardness. It has a nickel layer which provides a trademark, smoothness, and corrosion resistance; thus, we have two types of chromium plating, decorative and complex. Chromium plating is a prime metal coating used in various industries like aerospace and automotive.

Chromium Plating
Copper Plating

Copper Plating

It is the application of a thin layer of copper on the metal surface using an electric current hence improving the wear resistance of the character. Its good heat conductivity makes the plated metal suitable for printed circuit boards and precision engineering applications. The plating improves the flexibility of the coated products due to its excellent adhesion to base metals. Copper plating provides even results on most non-ferrous and iron base metals and is only applied to clean pickled steel products thoroughly.

Silver Plating

The process by which a metal is immersed and coated with a silver layer provides great solderability for small parts and corrosion resistance to the base material. It has a different level of thickness; hence the layer can be bright, semi-bright, or matte and thus can be used in power generators like solar, various musical instruments and electronics. Silver plating has a low price compared to gold plating, but they tarnish even after re-applying, although they work similarly.

Silver Plating
Rhodium Plating

Rhodium Plating

It combines gold, silver or any other base metal coated in a thin layer of rhodium to provide strength and luster. The item plated in rhodium is usually more durable since the plating does not dent, corrode or scratch and retains its luster. Rhodium is hypoallergenic since it does not contain nickel that can cause skin reactions; thus, it guards and keeps the skin safe. It also has corrosive resistance; hence, it does not rust and is soft; thus, it requires other metals that make it susceptible to tarnishing.

Zinc-Nickel Plating

Zinc-nickel plating is the alloying of nickel with zinc to offer corrosion resistance for the parts used in a harsh environment. It is preferable in applications where not all parts will be the same base metal because it reduces the galvanic potential with other used materials. The plating is usually used on components made of materials such as carbon steel or stainless steel when assembled with parts made of aluminum. Also, it used in hydraulic power transmission technology. Zinc-nickel plating is suitable for blackening when a black appearance is needed in the finished part and has a hardness of about 400 to 500HV.

Zinc-Nickel Plating

Electroplating Metals

Electroplating Metals
Electroplating Metals

Electroplating is a method when controlled electrolysis is used when coating an object in a layer of metals using electrodeposition from an anode to a cathode. The method is commonly used to build up the thickness of the substrate through the progressive use of thin layers. It enables you to combine certain metals’ strength, electrical conductivity, corrosion resistance and appearance with various materials.

It breaks down before the base material when a metal part is placed in a harsh environment, thus protecting the substrate from damage. Different metals land different properties. Thus, it prepares a surface for better paint adhesion, improves electrical conductivity and reduces friction.

Non-conductive substrates like wood, glass or plastic should be made conductive before they are electroplated; hence it can be done by coating them in a layer of conductive spray. Materials that are commonly used in electroplating to maximize strength and conductivity are;

  • Copper.

It is heat resistant and improves adhesion between layers of material.

  • Gold.

It provides wear and corrosion resistance and excellent conductivity, and aesthetic appeal.

  • Tin.

The metal is environmentally friendly, corrosive resistance, inexpensive compared to other metals and highly solderable.

  • Nickel.

This metal offers an excellent wear resistance which can be improved through heat treatment, and its electroless nickel plating has low friction and hardness.

  • Silver.

It is highly ductile and malleable, offering great aesthetics and good conductivity where needed.

  • Palladium.

It can be used instead of gold due to its hardness, corrosion and superb finishing.

Electroless Plating Metals (Autocatalytic)

Electroless Plating Metals (Autocatalytic)
Electroless Plating Metals (Autocatalytic)

Autocatalytic is one chemical reaction. A plate is usually inserted in a chemical reducing agent, which depends on the auto-catalytic reduction process of metal ions to form a deposit on the piece. The deposition involves metals like copper, nickel, silver, gold or palladium; hence they create an even layer of metal, and nickel is the most common metal used for electroless plating.

Many goods are coated with this plating, especially in plastics, providing attractive and durable surfaces. However, the most difficult edges, holes and irregular shaped objects that cannot be plated by electroplating are easily and evenly plated by electroless plating.

Autocatalytic plating does not use electrical power; hence complicated filtration method is not needed since the reaction is accomplished when a reducing agent releases hydrogen. The plating is applied chiefly to deposit a conductive surface on a nonconductive object to allow it to be electroplated; hence no complex gigue or racks are required. The plating protects from wear and resistance against corrosion and adds hardness to parts of all conditions. It is commonly used in engineering, aerospace, and oil and gas coatings.

Immersion Plating Metals

Immersion Plating Metals
Immersion Plating Metals

It is also known as dip plating; hence a nobler metal solution ion is applied to another metal surface to produce a replacement reaction. When the metal components like zinc are put into an electrolyte with nobler metal ions, the metal will dissolve. The metal is displaced by metal ions with lower oxidation levels, improving electrical properties and enhancing organic coatings. Immersion plating improves wear and corrosion resistance, electrical resistance, chemical resistance and hardness, electrical conductivity and bonding capabilities.

Applications Of Metal Plating Process

Water Treatment Industry
Water Treatment Industry.

Good metal finishing will prevent metals in this industry from rusting, making them last longer since they will be exposed more to water.

Gaming Industry
Gaming Industry.

This industry requires metal finishing that can easily be cleaned since it aims primarily at children; hence the metal used needs to have consoles that can be used severally.

Communications Industry
Communications Industry.

The metal used in this industry usually has good conductivity since they depend on electrical signals for the signal to flow or stop at any time.

Aerospace
Aerospace.

Plating on aerospace needs fine finishing since the metal must withstand harsh atmospheric conditions.

Medical Industry
Medical Industry.

The metal finish used to make devices in the medical industry must resist bacteria and be easy to clean; thus, the machines must be kept sterile.

Food Processing Industry
Food Processing Industry.

The metal finish must be bacteria resistant and easy to clean to keep the food safe; hence, the food preparation machines and metal conveyor belts must be sanitary.

Appliances
Appliances.

The devices here are usually exposed to water, food substances and harsh cleaning supplies; hence the metal finishing keeps them look clean and shiny.

Automotive
Automotive.

The metal used in automotive needs to be finished to ensure there is always a smooth-running engine; hence it can be for aesthetic reasons such as metal details on the outer side.

Metal Plating

People Also Ask:

Can All Metals Be Plated?

Absolutely yes.

Plating prevents rusting and protects against wear; hence you can plate all kinds of metals such as gold, zinc, cadmium, silver and nickel.

What Is Galvanic Plating?

It is the process by which water-based solutions are used to be deposited as ions leading to an oxide-reduction reaction when electrolysis and electrical energy are converted to chemical energy.

What Is the Difference Between Metal Painting and Metal Plating?

Metal plating provides an excellent and more robust finish than a metal painting; hence plating is the coating of metals by depositing them on a substrate.

Metal paint is applying paint to a metal part using a spray or pump for finishing.

What Are The Benefits Of Metal Plating?

The process of metal plating provides the following benefits to the material;

  • Increases strength.
  • Improves magnetism.
  • Decreases friction.
  • Reduces corrosion.
  • Enhances solderability.
  • Increases paint adhesion.
  • Gives aesthetic decoration.
  • Changes conductivity.

Related Resources:

What Is Metal Plating

Metal Plating

Plating

Electroplating Metal Plating

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