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5 Most Common Types Of Metal Coatings

Most Common Types Of Metal Coatings

Metals have been the preferred material for many long periods because of their strength, adaptability, and durability. However, corrosion is undoubtedly the most frequent and well-known issue that people deal with when using metals.

Numerous strategies have been put forth to lengthen the useful lives of metallic buildings and improve their corrosion resistance. Among these, metal polishing is one of the most effective and practical forms of defense.

Metallic surfaces can be coated using various techniques, each with its advantages and drawbacks. The article will cover the applicability of some of the most popular types of metal coatings for different purposes in detail in the following sections.

How Metal Coatings Guard Structures and Surfaces

Metal deterioration, or corrosion, is a process that takes place under particular circumstances. The most frequent form of corrosion happens when metals react with oxygen and moisture to produce different corrosion products. Rust is produced when iron combines with airborne oxygen and water to form iron (III) oxide. If you want to remove rust from metal tools, click to read the various processes.

The idea behind metal coatings is to surround the metallic object protected with an inert (non-reactive) layer to stop reactions with air and moisture.

5 Common Types Of Metal Coatings And Their Benefits

1. Anodizing

Anodizing is a technique used to encourage the development of a protective oxide coating on a metal's surface. The resulting oxide layer typically forms faster and is thicker than it would be if it were created organically. Although various non-ferrous metals can be anodized, aluminum responds fastest to the process. Aluminum components are electrolytically anodized by submerging them in an electrolytic solution and a cathode in a tank (usually aluminum or lead). For aluminum applications it is exposed to an electrical current, which causes it to oxidize and create a barrier of defense.

Of all the coatings covered in this article, anodized finishes are the easiest to maintain. Periodically cleaning anodized surfaces with mild detergents is simple. A finished anodized surface can have a durable coated surface since it is chemically stable and does not break down under typical circumstances. Anodizing is non-toxic and produces no hazardous by-products because it is a natural process.

The fact that this technique is only effective on a few metals is its biggest flaw. Because ferrous metals cannot be anodized, this method cannot process common materials like steel and iron. The techniques can also constrain the colors that can be produced by anodizing.

2. Galvanizing

The galvanizing process involves submerging the metal—usually steel or iron—in a bath of molten zinc. The coated metal forms a protective zinc carbonate layer when it is removed by reacting with atmospheric oxygen and carbon dioxide.

The numerous benefits of the galvanizing process make it a preferred option for many applications. For instance, a zinc oxide coating sticks to a metal substrate securely, is extremely stable, is long-lasting, and does not flake off readily.

Galvanized steel also offers galvanic protection. In other words, the zinc coating will sacrifice itself by corroding preferentially if the metal's surface gets exposed due to scratches, metal cuttings, or dents. This method aids in preserving the steel substrate between maintenance procedures.

The cost of the galvanizing process is its main drawback. Hot-dip galvanization (HDG) may be less expensive for large steel buildings, but it may not be as cost-effective for smaller items like nuts and bolts. Galvanized surfaces also have a drab, grey appearance, which may not be attractive for some applications.

3. Electroplating

The process of electrodeposition, commonly referred to as electroplating, entails depositing a thin layer of one metal on top of another. Both metals are submerged in an electrolytic solution during the electroplating process. The coated metal serves as the cathode, and the metal is coated as the anode. Metal ions migrate from the cathode to the anode when an electric current is given to the electrolytic cell, forming the coating.

Excellent corrosion protection is provided via electroplating, which can also improve some of the mechanical qualities of the metal. Electroplating also results in a visually appealing surface texture, making it suitable for covering jewelry and ornaments.

Electroplating, however, might result in coating thicknesses that are not uniform, rendering it unsuitable for high-precision applications. Additionally, the procedure is too expensive and labor-intensive for application on an industrial scale.

In the electroplating process, chemicals that could be toxic and hazardous are utilized as electrolytes. To prevent environmental pollution, care must be taken when dumping electrolyte compounds. 

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4. Coating With Powder

As the name suggests, powder coating entails covering an object with a material made of powder. The coating particles are electrically charged in an electrostatic process with polarities opposite those of the component to be coated. The powdered particles stick to the metal's surface due to the difference in charges. The coated object is then heated in an oven to firm the coating.

For their tenacity and attractive appearance, powder coatings are highly regarded. Additionally, there are hardly any volatile organic compounds (VOC) emissions because powder coatings don't employ solvents. Although powder coatings may be cost-effective in the long run, they also have high start-up expenses. Specialized spray booths, ovens, and spraying equipment are needed for the coating process. This may also constrain the size of things that you can cover.

Additionally, it is challenging—if not impossible—to create thin coating layers. In addition, compared to other coating techniques, the resultant surface is not the smoothest. Projects that need coatings with a thickness of fewer than six mills should use a different coating technique.

5. Paint Coating

In essence, applying liquid paint results in a painted layer. It is the most affordable and widely available type of metal coating. You can utilize several paint formulas depending on the type of metal, the working environment, and the performance requirements.

Other coating techniques are gradually superseding paint coatings for industrial purposes. Some paints may include poisonous substances and other volatile organic compounds (VOCs), which makes them environmentally dangerous. As a result of prolonged environmental contact, they are more likely to fade, peel, or flake off, making them less durable than other coating techniques.

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