Aluminum is an almost ideal substrate for adhesives. It has a high surface energy and is very resistant to most environments. It is also a material with good formability and high strength-to-weight ratio that can benefit greatly from properties offered by adhesive joining. As a result, adhesive bonded aluminum joints are commonly used in the aircraft and automotive industries as well as in a multitude of other structural and non-structural applications.
Aluminum's surface oxide forming ability provides excellent corrosion resistance and a surface providing high initial adhesive strength. However, this oxide layer is relatively complex and can be formed in many ways depending on the conditions present during its formation. The oxide layer can also provide significant problems for the adhesive formulator and the end-user - especially when it comes to bond durability in warm and humid climates. As a result, a prebond surface treatment is generally required for aluminum to stabilize and specifically define the oxide structure.