Electroplating is a process that occurs when the surface layer of one type of metal is added to another kind of metal. Also known as electrodeposition, this process is used to ensure that the metal base isn’t subjected to rust and corrosion. The thin layer of metal that’s positioned on top of another metal can alter the base metal’s physical properties, improve wear resistance, and increase material thickness. Electroplating is also commonly used to make a product more visually appealing.
There is a range of metals that can be used during the electroplating process, which include everything from copper and zinc to silver and gold. Even though modern advancements to electroplating have made this technique more popular than ever, the process was invented back in the 18th century. At the time, electroplating only existed as a basic experiment. It wasn’t until 1805 that Luigi Brugnatelli formalized the process, after which it was quickly adopted throughout most European countries. Since that time, advancements have continued to be made that allow electroplating to offer many distinct benefits.
The electroplating process always involves two different types of metals. In order for this process to occur, one of the two metals will need to be positively charged while the other is negatively charged. When an electrical current begins to flow from one metal to another, the negatively charged metal will take some molecules from the positively charged one.
For this process to work as intended, the layer of metal that you want to add to the surface of another metal must accommodate an electrical charge. This requirement means that it can be difficult to plate materials like wood and plastic that are unable to conduct electrical charges. You can bypass this issue altogether by thoroughly cleaning the material and applying a very thin layer of metal to the base material. Once you’ve found a material that can hold an electrical charge, the electroplating process can begin in earnest. This article offers you a detailed guide on the process and many uses of electroplating.
- Lend various surface properties – Once applied, the substrate can benefit substantially from the characteristics and properties of the metal that it is plated with. The plating metal you select can increase the electrical conductivity of the substrate or reduce material friction. Each plating material provides its own distinct benefits.
- Improve an item’s appearance – The electroplating technique is commonly performed to enhance the appearance of the substrate in question. Silver and gold are two popular plating metals that can improve the substrate’s appearance.
- Protect the substrate – If you want to protect the substrate surface from damage or corrosion, the plating metal can serve as protection for the substrate below. When the finished item is exposed to harmful conditions, the plating metal will be damaged first, which ensures that the substrate has more protection than it otherwise would have.
- Improve material thickness – It’s possible to add several layers of plating metals, which can help you improve substrate thickness.
Industries That Use Electroplating
Because of the many uses that electroplating has, there is a range of different industries that benefit from the electroplating process. The five primary industries that use electroplating are:
- Medical industry – It’s common for the medical industry to use electroplating to enhance component biocompatibility. Metals like titanium, gold, and silver are used in the medical industry for their wear resistance, corrosion resistance, and biocompatibility. In fact, this process is integral for the creation of joint replacements and implants.
- Automotive industry – The main purpose of using plating in the automotive industry is to keep corrosion at bay when the substrate is exposed to harsh environmental conditions. While zinc-nickel plating assists with rust prevention, nickel plating is commonly paired with plastic parts and catalytic converters as opposed to chrome.
- Aerospace industry – Titanium is commonly used in aircraft manufacturing because of its fantastic strength-to-weight ratio. Two other plating metals that are popular in the aerospace industry include copper for heat resistance and nickel to protect against wear and corrosion.
- Oil and gas industry – Because of the composition and volatility of petrochemicals, corrosion protection is essential. To ensure that piping is properly protected, nickel plating is applied via the electroplating process. Performing the electroplating process in this situation ensures that the parts can last longer.
- Electronics industry – Electroplating is also commonly used in the electronics industry for several applications. For one, gold plating is applied to connectors and semiconductors to ensure that the item is conductive. Gold is highly resistant to corrosion, which makes it perfect for the electronics industry. It’s possible for copper plating to provide the same benefits. Another type of metal that can be useful as a protective coating for electronic components and equipment is palladium alloy.
While these five industries use electroplating the most, this process is also used for several applications throughout the military and firearms industries. Along with the functional capabilities that electroplating provides, it’s also a flexible and affordable process.
Electroplating Process Explained
The electroplating process works by directly dissolving a metal with an electric current. The dissolved metal is then placed on the substrate metal. There are four primary components that must work together if you want the electroplating process to be effective. These components include:
- Cathode – The cathode is the substrate material that must be plated with another metal. This is a negatively charged material.
- Anode – This is the metal that forms the plating and is positively charged.
- Power source – An electric current is sent to a circuit with a power source of some kind. The power source will apply the current directly to the anode, which allows electricity to be introduced to the item.
- Solution – The reaction that takes place during the electroplating process occurs within an electrolytic solution. The solution consists of at least one metal salt that helps with the flow of electricity. It’s common for one of these salts to be copper sulfate.
When the cathode and anode have been properly placed in the solution, a power supply will send an electric current to the anode. The current ensures that the metals oxidize, which dissolves metal atoms into positive ions. The ions will then move over to the negatively charged metal to create a thin metallic layer. The three factors that play a part in the plating quality include:
- Electric current – The success of this process is determined by the application time and voltage level of the electric current.
- Bath conditions – The chemical composition and temperature of the solution dictates what the results of the electroplating process will be.
- Part placement – The effectiveness of the plating can be determined by how close the anode is in comparison to the cathode.
If you want a real-life example of how the electroplating process works, consider what happens when gold is plated onto metal jewelry. While the jewelry exists as the cathode, the gold plating acts as the anode. These metals are then positioned in a solution, after which an electric current is sent to the gold.
The gold will dissolve within the solution, which creates dissolved gold atoms. These atoms will be attracted to the negatively charged metal, which is the jewelry. If performed correctly, the gold atoms will stick to the metallic surface to create a gold coating.
Different Plating Techniques
There are three primary plating techniques that can be used with the electroplating process, which include:
- Rack electroplating – This technique is ideal for plating sizable groups of parts. When using this method, the parts will be placed directly on a wire rack, which ensures that every part comes into contact with the power source. While this process is similar to barrel plating, it’s better for delicate parts that wouldn’t be able to withstand the barrel-plating process.
- Electroless plating – This plating technique is the only one that doesn’t require the parts to come into contact with an electric current. To bypass this requirement, the plating material of your choice is dissolved with a chemical reaction. This particular technique is best used on parts that don’t accommodate electric currents.
- Barrel plating – This plating technique is ideal when large amounts of smaller parts need to be plated. These parts will be positioned inside a barrel that’s filled with the electrolyte solution of your choice. From here, the barrel is rotated, which helps to agitate the parts and apply an even coating.
Metals Used Throughout the Electroplating Process
As touched upon previously, there are many different metals that can be used in the electroplating process. The metal that you choose depends on the substrate composition and your preferred price. The main metals used in the electroplating process include:
- Nickel – This metal provides fantastic wear resistance. The different nickel alloys can also provide the substrate with better conductivity and elemental resistance. As for electroless nickel plating, it can help provide low friction, corrosion resistance, and magnetism.
- Silver – This metal is malleable, ductile, and highly wear-resistant. It’s a more affordable alternative to silver.
- Gold – This metal provides high wear and corrosion resistance as well as fantastic conductivity.
- Palladium – This metal offers a sleek finish, hardness, and corrosion resistance. When you combine palladium with nickel, the plating quality is superb.
- Zinc – This specific metal has great corrosion resistance and can be enhanced when alloyed with other metals.
- Copper – Along with improving material adhesion, copper is ideal when used for its heat-resistant and conductive properties.
- Tin – This metal is environmentally friendly, inexpensive, and resistant to corrosion.
Benefits of Electroplating
The electroplating process comes with many benefits the primary of which include:
- Heat resistance – When metals with high heat resistance are used in the electroplating process, the substrate materials can withstand heat damage. By keeping heat damage at a minimum, plated parts should last longer.
- Added protection – As an added layer of protection, plated metals can protect the substrate from harsh environmental conditions.
- Better hardness – Plated materials will invariably be stronger and more durable, which keeps stress damage at a minimum.
- Electrical conductivity – Plating metals like copper and silver can enhance the conductivity of substrate materials. This cost-effective solution is very popular in the electronics industry.
- Improved appearance – Plating metals like silver and gold improve the appearance of base metals that may inherently have worse appearances.
Keep in mind that these benefits are dependent on the metal you use in the electroplating process. For instance, nickel plating keeps wear and tear at bay, which bolsters part longevity. Because of its flexibility and the many applications, it can be used for, electroplating is a highly important process across numerous industries. If you want to strengthen a substrate or improve its appearance, electroplating offers a cost-effective solution.