What Is Hard Anodize and When Should You Use It?
Hardcoat or hard anodize is a type of metal surface treatment used primarily on aluminum components, and is one of the three main types of aluminum anodizing, as well as one of the services that Reid Metal Finishing offers. While it still follows the same basic premise of anodizing by transforming the natural aluminum oxide layer on a part’s surface into a protective coating, hard anodize treatments have some differences from other types of anodization.
Hard Anodize Treatments for Aluminum: Type III of Three
Hardcoat anodizing is the third of the three major types of aluminum anodizing techniques. Of the three, hard anodize results in the hardest and most wear resistant surface coating. The oxide layer is formed under much more precise conditions in order to get a denser layer, typically for applications where the parts will experience constant metal-on-metal wear or regular abrasion.
Unlike the other two types of anodizing however, hardcoat anodize coatings are difficult to dye. Because the layer is thicker and denser, the coating tends to take on a darker gray appearance that is hard to color. Our customers typically leave the natural surface color as is or request a black coloring for improved uniformity, which while not as versatile, still offers a pleasing aesthetic appearance.
How it Works
Like other types of anodizing, hardcoat anodizing uses the natural formation of aluminum oxide that occurs on the surface and essentially toughens it up, improving the natural corrosion and wear resistance of the layer.
- First, the aluminum parts are thoroughly cleaned and deoxidized, and any necessary sections are masked.
- Next, the parts are submerged into a chemical bath, usually containing sulfuric acid. A measured and constant voltage is applied to the bath in order to kickstart a controlled oxidation reaction for a specified time (depending on the desired thickness and properties of the coating).
- Once the specified time has elapsed, the parts are removed and dried and prepared for any post processing.
The Benefits and Common Applications of Hardcoat Anodizing
Though the resulting layer of Type III Anodization is thicker than other anodizing types, hardcoat anodizing offers the strongest resistance to abrasion, wear, and corrosion. It’s easy to sterilize, making it excellent for healthcare related and food processing applications. Its high hardness makes it suitable for a number of functional and structural components, where metal-on-metal wear is common.
About Reid Metal Finishing
Reid Metal Finishing (RMF) is a premiere supplier of metal finishing services such as hardcoat anodize treatments and much more. Head over to our website to view all of our services and request a quote.
