The Effect of Aluminum Oxide Structure on Adhesive Bonding

When one wishes to bond aluminum alloys and obtain durable bonds, it has been conventional practice to clean and remove the mill oxide chemically and deposit another oxide surface which then is more receptive to forming a strong adhesive bond. Much work has been done in recent years by the adhesive manufacturers to develop adhesive systems which produce durable bonds to untreated surfaces. Their efforts using reactive acrylic and rubber modified epoxies have been largely successful. The more one knows about the surface to be bonded, the better the possibility of producing a durable bonding system. This paper addresses some of those factors concerning the aluminum oxide surface. A model for the aluminum oxide structure is presented and evidence given that indicates that with 5182 alloy, bond failure can be related to failure of the magnesium oxide within the aluminum oxide structure.