ABSTRACT
Understanding the microstructure and chemistry of the aluminum surface is the key to designing coating and structural bonding systems that endure. In important practical applications, bonding of structural components in aircraft, lacquer systems in packaging, paint, and decorative coatings for architectural, automotive, and general engineering components, the adhesion is generally of a polymer to the aluminum surface. The polymer layer may be a phenol or epoxy structural adhesive, a polyethylene, or other polyolefin coating in flexible packaging systems, or a paint or lacquer. Examples of systems involving bonding of a polymer layer to an aluminum substrate are shown schematically in Fig. 1. In each case, the polymer and the aluminum substrate are linked through the oxide layer on the surface of the metal. This layer, which may be as thin as a few nanometers, plays a crucial role in determining the strength and endurance of the bonding system, and much effort is spent on designing and maintaining a pretreatment schedule which ensures that it is engineered to have the optimum composition and microstructure. The ‘optimum’ composition and microstructure will vary from system to system and will depend on the nature of the polymer layer, the mechanical requirements of the bond, and the environment it will be exposed to in service. Schematic of the interface region for two polymer/aluminum systems. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429223259/a9a44f48-abbd-4f84-9837-bef5a3a56592/content/fig12_1.tif"/>
