Enhancing Metal Parts: The Benefits of Zinc, Nickel, and Chrome Plating

When it comes to protecting metal parts and giving them a shiny finish, customers often choose from three common methods: zinc plating, chrome plating, and nickel plating. Let’s take a look at the applications of these three electroplating technologies and features.

Content
1 What is electroplating?
2 What is galvanizing?
3 What is nickel plating
4 What is chrome plating
5.Zinc plating, nickel plating, chrome plating
6.Benefit of metal plating 
7  Conclusion
8  Frequently Asked Questions

Part 1 :  What is electroplating?

Electroplating uses an electric current to convert metal ions into a thin, smooth coating of metal on a surface. This can strengthen a part, protect it from rust and wear, and improve its appearance. Zinc plating, nickel plating, and chrome plating are all standard electroplating processes.

Part 2 :  What is galvanizing

Galvanizing is a protective process that coats metal surfaces with a zinc layer to improve corrosion resistance. The zinc layer acts as a barrier, preventing air and moisture from entering the metal and causing rust. Even if the zinc layer is damaged, it will oxidize first, protecting the metal underneath from corrosion.

There are two main types of galvanizing: hot-dip galvanizing and electroplating.

Hot-dip galvanizing is the process of dipping metal into a bath of hot zinc. This creates a thick layer of zinc that helps prevent the metal from rusting. It is often used on outdoor structures such as bridges, fences, and utility poles.

Electroplating is the process of depositing a thin layer of zinc on a metal surface through an electrochemical process. This produces a smooth, shiny surface that is ideal for products that require an aesthetically pleasing appearance, such as small hardware and appliance parts.

The blue galvanizing we often see on screws and nuts not only improves their appearance with a bright, slightly bluish silver finish, but it also helps prevent rust, making it both protective and visually appealing.

Part 3 : What is Nickel Plating

Nickel is a shiny, light-golden metal. Nickel plating is accomplished through an electrochemical process in which nickel ions are deposited on the surface of a part. The part, acting as the cathode, is placed in a solution containing a nickel salt (such as nickel sulfate and nickel chloride) and a reducing agent. When an electric current is passed through it, the nickel ions move from the solution to the surface of the part, forming a smooth, even nickel coating.

Decorative nickel plating is usually a thin layer (about 5-15 microns) and is mainly used to improve the gloss and appearance of the product. It is often combined with chrome plating to decorate items such as home appliances and furniture accessories.

Thicker protective nickel plating helps improve the component's resistance to rust, wear and oxidation. It is commonly used in chemical equipment, instrumentation components and outdoor applications.

Chemical nickel plating does not require electricity and forms a nickel layer on the surface through chemical reaction. The coating is uniform and very suitable for parts with complex shapes. Chemical nickel plating also has excellent corrosion resistance and hardness, and is widely used in aerospace, automobiles, precision instruments and other fields.

Nickel plating protects against rust and wear while giving the product a lustrous finish. It is commonly used on hardware, electronic parts, and automotive components. Electroless nickel plating is well suited for parts with complex shapes. However, nickel plating is costly, especially electroless plating, and requires special waste disposal, which can have an impact on the environment. In addition, the surface of the part needs to be clean and smooth, otherwise the coating may not adhere well or evenly.

Part 4 :  What is Chrome Plating
Chromium is a shiny, silvery-white metal with a slightly bluish sheen. Chromium plating is done through an electrochemical process in which chromium ions are transferred from a plating solution to the surface of the part. The part acts as the cathode and a chromium salt (e.g. a solution of chromic acid and sulfuric acid) decomposes under the action of an electric current, depositing a smooth, uniform layer of chromium on the surface. This coating has excellent wear resistance, corrosion resistance, and aesthetics.
Chrome plating can be divided into decorative chrome and hard chrome.

Decorative chrome is mainly used to improve the appearance of the product while providing a certain degree of corrosion resistance. The coating is thin (usually 0.5 to 1 micron) and is usually applied as an outer layer on the nickel-plated surface for decorative purposes.

Hard chrome coatings are thicker (typically 10 to 500 microns) and offer excellent wear resistance, low friction and high hardness. They are often used to extend the service life of mechanical parts such as hydraulic rods, engine pistons and industrial molds.
Hexavalent chromium (Cr) is the most harmful form of chromium and is recognized as a human carcinogen. The waste generated by hexavalent chromium electroplating solution is toxic and must be properly treated before discharge.

Trivalent chromium (Cr 3+) plating is made from chromium sulfate or chromium chloride and can be a safer alternative to hexavalent chromium in certain applications and thicknesses. It is also more environmentally friendly but requires careful handling and disposal.

Part 5 : Galvanizing, nickel plating, chrome plating

5.1 Corrosion resistance

Galvanizing > Nickel plating > Chrome plating (depending on thickness)

Galvanizing: The zinc coating protects against corrosion, especially on steel products. It acts as a sacrificial anode, and even if the surface is damaged, the zinc will oxidize first, protecting the base metal. Galvanizing is ideal for steel structures that are exposed to moisture and outdoor environments.

Nickel plating: Nickel plating has excellent corrosion resistance, especially in humid and weakly acidic environments. However, the electroplated nickel layer is prone to pinholes, so chemical nickel plating is usually used to obtain better corrosion resistance.

Chrome plating: The corrosion resistance of the chrome plating layer depends on its thickness. The decorative chrome plating layer is thin and the anti-corrosion effect is limited.

5.2 Wear resistance

Chrome plating > Nickel plating > Zinc plating

Galvanizing: The zinc layer has low hardness and medium wear resistance, and is not suitable for high wear environments.

Nickel Plating: Nickel has moderate wear resistance, but chemical nickel plating has higher hardness and better wear resistance, making it ideal for precision parts.

Chrome plating: Hard chrome plating has high hardness and excellent wear resistance, which is very suitable for high-wear parts such as cylinders, piston rings, and molds. The hardness of hard chrome can reach HRC 65-70, which greatly extends the service life of parts.

5.3 Appearance and aesthetics

Chrome plating > Nickel plating > Zinc plating

Galvanizing: The standard galvanized layer is silvery white with a rough surface, but blue zinc and yellow zinc have better decorative effects.

Nickel plating: Nickel plating can make the surface bright, but the brightness is slightly lower than chrome plating, and it may be slightly yellow. Nickel plating is often used for hardware and home appliance parts, and can also be used as a base for decorative chrome plating.

Chrome plating: Chrome plating provides a bright mirror-like high-gloss surface and is therefore widely used for decorative purposes such as automobile and motorcycle parts, electrical appliance housings and bathroom fixtures.

5.4 Thickness and uniformity

Nickel plating (chemical plating) > zinc plating (electroplating) > chrome plating

Galvanizing: The electroplated zinc layer is thin and uniform, suitable for smoother surfaces.

Nickel Plating: Electroless nickel plating provides excellent thickness and uniformity, even on complex shapes.

Chrome plating: Chrome plating is thicker but may show local variations, so it is not suitable for complex shapes.

5.5 High temperature resistance

Chrome plating > Nickel plating > Zinc plating

Galvanizing: The zinc layer is not stable at high temperatures and may oxidize and peel off.

Nickel Plating: Nickel has good resistance to high temperatures but may discolor, especially in electroplated form.
Chrome plating: Chrome can maintain its hardness and surface stability at high temperatures, preventing discoloration and softening.

5.6 Differentg cost

Galvanizing (low cost) > Nickel plating > Chrome plating (high cost and great environmental impact)

Galvanizing: The cost is relatively low.

Nickel plating: Chemical nickel plating is more expensive.

Chrome plating: Electroplating processes are relatively expensive, especially hard chrome.

Part 6 Benefit of metal plating 

Metal plating is the process of applying a finish that alters the surface of a metal object. It requires a high level of precision and when done correctly, offers a wide range of benefits. If your business manufactures metal products, metal plating surface is a vital process to prevent corrosion, rust, and wear.
The lifespan of metal products without metal plating is significantly reduced, leaving it exposed to scratches, air pollution, and chemicals. Consulting metal plating companies ensures a high level of skill and service that can be relied on.  We’ve detailed our top 4 benefits of metal plating.
6.1 Heat Resistance
Metal plating increases the heat resistance of products, particularly when using a silver-plating process, which has a very high heat threshold. This benefit makes metal finishing a popular choice for aviation and automobile manufacturing, where exposure to high temperatures is unavoidable.

6.2 Increased Durability
Metal finishing increases the strength and hardness of metals, improving the endurance of the product. Copper and chrome plating are finishes commonly used for this purpose in industrial applications, including on tools, hydraulic cylinders, and mechanical products. If you have an old part that needs restoring or a new part that you want to protect, metal plating is a great solution.

6.3Improved Appearance
Not only does metal finishing improve the longevity of metal, but it can also significantly enhance the appearance. Antiques and jewellers commonly plate their items with a gold or silver coating to improve their visual appeal.

6.4 Electric Conductivity
surface plating can help improve the conductive elements of raw metal parts. Copper, gold, and silver are three ideal plating choices to increase conductivity. Our team at Dongguan China can recommend the right electroplating services for your business needs.

 Part 7 : Metal Part Application

Chrome plating is ideal for parts that require high wear resistance, hardness and an aesthetically pleasing surface, such as automotive components, tools and machinery.

Nickel plating is best suited for parts that require excellent corrosion resistance, wear resistance, and high precision, and is commonly found in electronic connectors, automotive parts, and hydraulic systems.

Galvanizing is an affordable rust-proofing solution used extensively on outdoor equipment, building components, and hardware such as screws and nuts.

Part 8  : FAQ
 How to remove chrome plating?
Hydrochloric acid is generally used to remove the chrome plating, but sandblasting, electrolysis and other methods can also be used.

 What is the difference between electroplating and chemical plating?

 Electroplating requires an external current and an anode, while chemical plating relies on an autocatalytic reaction occurring on the metal surface.

 Will galvanized steel sheets rust?

Galvanized steel pipes are not easy to rust, but they will be oxidized if they are placed in a humid environment for a long time. Generally, hot-dip galvanized pipes are less likely to rust than cold-dip galvanized pipes.

 How to clean nickel plating?

 To clean the nickel plating, wipe gently with a soft cloth and soapy water, then rinse, dry, and polish with a nickel-safe polish if necessary.