Adhesive bonding has long found application in airframe manufacturing owing to benefits including load transfer efficiency compared to mechanical fastening and a cost reduction potential. A major challenge for more widespread use of bonding is the lack of reliability for bonding, and prebond surface contamination is one of the major threats to ensure sound adhesion as it is difficult to completely prevent contaminants from migrating during long manufacturing steps. This work has focused on quantifying the effect of contamination on the bond performance for aerospace grade composite joints bonded with a structural epoxy film adhesive. Specifically, the tolerance to contamination for different surface treatments including peel plies and atmospheric pressure plasma, as well as for co-cured joint was compared. Prebond surfaces were characterized by surface free energy and X-ray photoelectron spectroscopy. A silicone based release agent was chosen and applied on prebond surfaces at various weights. Mode I fracture energy determined for a range of contamination levels using the Double Cantilever Beam (DCB) specimens was compared and contrasted between different surface treatments or boding types to discuss assumed factors to make the differences.
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