Evaluation of aluminum surface factors affecting the adhesive strength of epoxy adhesives

The relationship between the surface condition of heat-treated aluminum and its adhesive strength to epoxy adhesives was investigated. The adhesive strength was determined by 180-degree peel test. The chemical state of the aluminum surface was evaluated using Fourier transform infrared spectroscopy (FT-IR) and Time of flight secondary ion mass spectrometry (TOF-SIMS). The results showed that adhesive strength was decreased with increasing heat-treatment temperature above 120°C and the amount of hydroxy group on the aluminum surface was decreased with increasing heating temperature. There was a significant linear relationship between the adhesive strength and the amount of hydroxy group. From these results hydrogen bonding is concluded to be the dominant factor of the adhesion.