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All You Need to Know About Coated Metals
Applications involving ferrous metals like steel may require that the material undergo a coating process before it’s suitable to use. Through one of several techniques, manufacturers can coat the surface of the metal with an alloy or other material to prevent corrosion and rust, enhance wear resistance and appearance, and achieve particular performance goals. Learn more about the types of coated metals available as well as their applications and benefits.
What Are Coated Metals?
Coated metal surfaces provide added protection for the material underneath and can prevent rust and corrosion that might otherwise develop from exposure to chemicals, air, or water. There are multiple coating materials and techniques that manufacturers can use, depending on the specific needs of the application.
Manufacturers throughout numerous industries rely on coated metals to safeguard their products from damage. Industries with the highest need for metal protective coatings include:
- Rainwater goods
Manufacturers have many types of coated metals to choose from, each one delivering its own unique advantages. The most common types of coated metals include:
- Galvalume This type of steel is a structural, commercial, drawing, and forming variety that has undergone galvanization with an aluminum alloy consisting of 45% zinc. It’s beneficial for its ability to retain its flatness, its superior resistance to corrosion as compared to standard galvanized steel, and its compatibility with painting processes. Galvalume steel is useful in applications such as ducting, varied paneling, and computer housings, to name a few.
- Galvanized To safeguard against corrosion, the galvanizing process applies a zinc layer overtop a ferrous metal. The most common method is hot-dip galvanizing. During this process, you dip steel material into a molten zinc bath to coat it. When you reexpose the material to the air, the zinc reacts to the oxygen immediately, resulting in a zinc-oxide layer of superior strength and corrosion resistance. Together, the steel and zinc create a metallurgical bond, which prevents flaking. Galvanized coatings are available in several weights, including G40, G60, and G90.
- Electro-galvanized. The electro-galvanizing process utilizes an electrical current to bond a zinc or zinc-iron coating with steel through an electrolytic technique. Electro-galvanized metal will have a uniform coating thickness, a smooth appearance with a matte finish, and a paintable surface post-priming. Metals that have undergone this process are ideal for automotive paneling applications.
- Prepainted cold rolled and galvanized carbon steel Prepainted steel offers excellent coating coverage and uniformity, resulting in improved corrosion resistance and minimized manufacturing time, since it eliminates the need for drying. This technique is suitable for high-volume production in numerous prepainted colors and texture choices. Prepainted steel is common in consumer appliance, automotive, and metal roofing applications.
- Galvannealed Coated with a zinc-iron alloy, galvannealed steel provides good flatness, formability, and weldability while still allowing for surface painting. It offers lower resistance to corrosion than galvalume steel, but it’s still advantageous in electrical components, doors and framing, and exterior signage.
- Aluminized Aluminized metal coating involves surrounding a steel component with pure aluminum, which results in maximum corrosion and thermal resistance. Steel with an aluminum coating is applicable for many industrial tasks, such as HVAC systems, heat exchangers, and products for high-heat environments, such as baking sheets. When comparing aluminized steel vs. galvanized steel, aluminized steel can withstand significantly higher temperatures.
- Tin plate Tin plating involves covering a steel surface with tin in thin layers, providing optimal solderability and corrosion and rust resistance. As tin is a ductile material, products with tin plating have good formability, allowing you to produce components in various configurations without damaging the plating.
- Bonderized The bonderizing process involves putting cleaned galvanized steel through a phosphate bath followed by a chromate dry to produce a crystalline zinc-phosphate layer. The resulting finish is an excellent paint primer that improves paint’s lifespan, but you should be ready to use the material immediately to prevent white rust. Also known as paint grip steel, bonderized steel has ideal uses in roofing applications, flashing, gutters, downspouts, outdoor signs, and more.
- Anodized When anodizing, manufacturers immerse a metal component within a tank containing an electrolytic solution and a cathode of lead or aluminum. As electric current passes through the component, the process encourages a non-toxic oxide layer to form overtop the metal’s surface for greater protection and easy maintenance. Anodizing ultimately creates a thicker layer faster than if a surface were to oxidize naturally, and provides good chemical stability for a lasting coating. Anodizing is ideal for aluminum in particular and works with several non-ferrous metals, but all ferrous metals, including iron and steel, are incompatible with the process. Color options are also limited.
Benefits of Coated Metals
Metal coating techniques make ferrous substrates suitable for long-lasting use in their applications. Coated metals provide:
- Enhanced product lifespan due to products’ surface strength
- Durability and minimal friction, even in high-contact components
- Resistance to abrasion, general wear, galvanization, oxidation, rust, corrosion, chemicals, and electricity damage
- Electrical conductivity (beneficial for commercial and industrial parts)
- Polished, aesthetically pleasing finishes free from surface flaws
- Increased torque, with effortless lubrication of fasteners or related components
- Simplified assembly, disassembly, and – given coatings’ non-stick nature – cleanup tasks
- Budgetary savings
Coated Steel and More From Continental Steel & Tube Company
Coated metals increase the durability and lifespan of the components that manufacturers use these materials to produce. As a leading global supplier and distributor of high-quality metals, Continental Steel can help you identify and source the most suitable coated metal for your application. To learn more about our material options and industrial metal coating, contact us today.