Metal sometimes needs additional layers of protection to enhance resistances to chemicals, moisture, and abrasion. There are multiple different treatments that can provide protection, each best for different metals, environments, applications, and budgets. Options include processes like metal plating, powder coating, hardening, and anodizing.
What is Anodizing?
Anodizing is an electrochemical treatment process that makes aluminum surfaces more resistant to damage. The process also works with other non-ferrous metals, such as magnesium or titanium, but is most typically used on aluminum sheets and parts.
The anodization process changes the topmost surface layer of the aluminum into an oxidized layer that rebuffs further damage. This layer is one of the hardest materials available, second only to diamonds. Left completely bare, aluminum may corrode from contact with water, chemicals, and acids. While aluminum does have a good degree of innate resistance to corrosion due to a naturally forming oxide surface layer, that natural protection isn’t enough for many harsh industrial applications.
Aluminum is also vulnerable to scratches that can pierce through the oxidized layer and leave the metal exposed to damage. However, the enhanced oxidized layer provided by anodization makes the material much more resistant to both abrasion and corrosion.
For aluminum consumer goods and visible aluminum parts, anodizing has another key benefit: It creates an aesthetically pleasing surface. Manufacturers can further treat this surface with dyes and polish to create the finished appearance of their choosing.
What Does the Anodizing Process Entail?
Anodizing processes use chemical baths and electric currents to alter the surface of the aluminum. First, manufacturers submerge the aluminum components in a sulfuric acid bath. The acid erodes the surface and pulls positive ions out of the material through newly developed pores. At the same time, manufacturers attach electric charges to the metal and placed in the bath.
Electrolytes are added to the acid bath as well because negative ions attach to metal. When the negatively charged dioxide molecules interact with untouched layers of aluminum, it starts to create aluminum oxide. The acid corrodes the metal to create a thick and controlled oxidized layer.
This new oxide layer is hard and permanent. Depending on the thickness, the layer can range from gray to black in color. However, it’s also very porous.
The second step of anodizing aluminum is sealing the new protective layer. Placing the aluminum parts in warm water will shrink the pores by hydrating the ions, creating a hard, finished surface layer. This opportunity may also be used to color the ceramic layer by adding dyes to the water. The pores will absorb the coloring along with the water before shrinking and setting.
What are the Benefits of Anodizing Aluminum?
Anodizing is one of the best treatment methods for making aluminum more resistant to physical and chemical damage. Some of the key benefits of anodizing aluminum include:
Lightweight
Aluminum is already a lightweight metal with a good strength-to-weight ratio. Anodized aluminum maintains its lightweight nature for more affordable, easier shipping.
Recyclable
Aluminum is one of the most easily repurposed and recycled metals. The anodizing process doesn’t impact the recyclability of the material, which makes it ideal for sustainable production that considers the full lifecycle of the product.
Customizability
Anodizing offers myriad color options to suit the needs of nearly any design or application, and dyes can be formulated to match any branding or design need. Anodized aluminum products can also be made to look like other metals, such as gold or brass. Though the anodization process leaves a shiny surface on aluminum products, the final finish can be customized as well for texture and brightness.
Durability and Long-Lasting Strength
Anodization makes aluminum stronger, longer-lasting, and more durable in a wider variety of environments and applications. The surface becomes three times as hard as untreated aluminum, leaving it resistant to abrasion, corrosion, and physical impact damage. Anodization chemically changes the surface of the aluminum, unlike painting or plating, so the protective layer is permanent—an anodized finish won’t chip, flake, or rust over time.
Cost Savings
Anodizing processes give companies access to long-term savings. Anodized aluminum offers a much more cost-effective alternative to other metals in many applications. Anodized aluminum boasts a lower cost per square foot than most other metals, such as steel, brass, copper, or zinc. As the most recyclable metal, aluminum and anodized aluminum are always readily available on the market.
What are Common Applications and Uses for Anodized Aluminum?
Aluminum is used in almost every industry around the world. The versatile nature of anodized aluminum makes it useful for manufacturing a wide array of goods. Industries that rely on anodized aluminum include:
Architecture
Anodized aluminum pieces can be customized to hold almost any finish, texture, or color. Architects and designers use this feature to create an array of custom products and visual elements. Aluminum is ideal for lighting fixtures, interior and exterior accents, and more.
However, anodized aluminum isn’t just aesthetically pleasing. Its favorable strength-to-weight ratio also makes the material a good candidate for roofs, framing, and supports. The weight of a building’s support structure ultimately contributes to the overall weight of the building, so using lighter weight aluminum supports allows for more efficient building design. The material’s resistances to corrosion and abrasion make it ideal for constructing long-lasting outdoor building components as well.
Consumer Goods
Anodized aluminum is popular for its aesthetically pleasing surface appearance and long-lasting performance with minimal maintenance. Consumers use products with anodized aluminum components every day, ranging from sporting goods to small appliances to luxury vehicles.
Automotive, Marine, Aerospace
The lightweight nature of anodized aluminum makes it an excellent material for constructing cars, trains, boats, and aircraft interiors. Automotive, marine, and aerospace manufacturers have turned to plastics and fiberglass to reduce vehicle weights, but only a metal material will do for many components. Anodized aluminum offers a durable alternative to steel for applications where weight impacts fuel efficiency.
Tri-State Aluminum's Anodized Capabilities
At Tri-State Aluminum, we provide anodized bars, rods, and tubes and custom stock shapes for your manufacturing or building project. We can meet any custom color needs with our specialized two-step electrolytic coloring process. We have over 25 years of experience supplying custom extrusions, fabricating aluminum products, and providing wholesale extrusions. Contact us today or request a quote to learn more about our capabilities.