Anodized Aluminum Curtainwall Extrusion

This common product describes an aluminum extrusion, anodized with a clear surface coating, as is common in curtain walls. The aluminum alloys typically used in curtain walls come from the 6xxx series, more specifically 6063 in either a T5 or T6 temper. These tempers are chemically identical, but have been put through different heat treatments to impart slightly different strength and performance characteristics. Because they are part of a building exterior, extruded aluminum for use in curtain walls includes a surface treatment. Anodized treatments and PVDF coatings are most common for this application (see PVDF-Coated Aluminum Curtainwall Extrusion). Anodizing is a process similar to electroplating, where electrical current is passed through a conductive bath in which the item being anodized is submerged. The current accelerates the oxidizing process that would naturally occur to the aluminum if exposed to the elements over time, and produces a surface layer of protective aluminum oxide. There are several types of conductive baths that can be used, but sulfuric acid is most common. Anodizing can include the use of added colorants and dyes to create a variety of colors, however this is a review of extrusions without added colorants. After anodizing, the extrusion must be sealed. Boiling in deionized water is the simplest technique for sealing. The end result of the anodizing process is that the surface layer of aluminum has been chemically converted into hydrated aluminum oxide, which protects the underlying aluminum from damage. The dimensions of curtain wall framing are customizable. Based on a sample review of product literature, percentages are based on a segment of anodized aluminum extrusion 24 feet long, 2.5 inches wide, 6 inches deep, and .125 inches thick. For estimation purposes, we’ve assumed a simplified geometry and have excluded grooves, etc. from our calculation of surface area.