Effect of surface treatment on the durability of aluminium joints bonded with a butadiene–acrylonitrile–epoxide sealant

A sealant made from a stoichiometric mixture of amine terminated butadiene–acrylonitrile copolymer and epoxide resin has been used to make single lap-joints in aluminium. These have been immersed in jet-fuel, water, antifreeze and an antifreeze–water mixture prior to testing. Strengths were much increased by pre-treating the metal by phosphoric acid anodization or with silane coupling agents. Joints were weakened in antifreeze but not in jet-fuel or antifreeze – water. In water weakening of joints with the silanes is accompanied by corrosion.