The use of aluminum in cars is expected to nearly double by 2025 as OEMs seek to reduce weight; aluminum today is already the second-most-used material to produce cars. Many OEMs are expanding aluminum use from heat exchangers, wheels, drive shafts, engine blocks, hoods and deck lids to developing aluminum intensive vehicles (AIVs) by converting the body in white, or body structure, to aluminum. As OEMs use aluminum body structures to improve fuel efficiency, new joining and assembly methods are required. “Alcoa 951” is a patented, non-chrome approach for enhancing bond durability and enabling more cost-effective, mass production of AIVs.

In customer trials, “Alcoa 951” has been proven to be up to nine times more durable than titanium zirconium applications used in the automotive industry in the past, according to Alcoa. These results led OEMs to specify “Alcoa 951” and request Alcoa to license it to other suppliers in the industry—hence the agreement with Chemetall. “Alcoa 951” technology is being incorporated into the $300 million automotive expansion underway at Alcoa’s Davenport (Iowa) Works facility, scheduled for completion by the end of 2013.

We look forward to partnering with Chemetall to provide ‘Alcoa 951’ to help enable commercialization of adhesive bonding of aluminum structures in high-volume automotive applications. This, in turn, will drive lighter vehicle weights and enable the integration of sheet, extrusions, and castings to ultimately improve fuel efficiency. The process was developed as a result of collaboration between the Alcoa Technical Center and our automotive business. We’re excited to see it commercialized.

—Dr. Raymond Kilmer, Alcoa Executive Vice President and Chief Technology Officer

“Alcoa 951” employs an organic system tailored for both the aluminum substrate and the structural adhesives used for joining. The pre-treatment delivers far superior bond durability compared to conversion coating systems such as the titanium zirconium often used in the past. Customer trials show its durability is up to nine times stronger than titanium zirconium, according to Alcoa

The surface treatment is applied through an immersion or spray application in which the organic components bond with oxides present on the metal surface. The molecular structure chemically binds aluminum oxide with one end, and adhesive with the other. This creates a strong link at the molecular level resulting in lasting, durable joints for automotive structures.

The minimal level of treatment on the surface makes it essentially “transparent” to downstream steps in the automotive manufacturing process such as forming, resistance spot welding and painting.

Other commercially available conversion coatings, which generally contain heavy metals and are measurably thicker, lead to potential environmental concerns and diminished performance in other steps in the manufacturing process. The attractiveness of “Alcoa 951” lies in its repeatability and its simplicity, the company says. It does not incorporate exotic components that threaten the ability to implement the product on a large scale, and it brings the type of benign environmental impact that addresses the need for the “cradle-to-cradle” life cycle required for aluminum.