Abstract
Ageing of adhesive-bonded aluminium-dicyandiamide cured epoxy alumina-filled joints prepared using a variety of different surface treatments and exposed to elevated temperatures and high humidity are reported. The uptake of moisture was followed using broadband dielectric spectroscopy, and attempts are made to correlate these changes with observations of variations in the mechanical properties and surface structure monitored by electron microscopy. It was found that the absorption of moisture, as indicated by the dielectric measurements, is similar for all the joints. Small differences observed may be ascribed to the influence of the pretreatment on the absorption behaviour. There was no evidence of changes in the oxide layer of the substrate. Detailed electron microscopic examination of the surfaces did indicate, after prolonged exposure, that change in the pretreatment is consistent with small differences in the dielectric data. Predominantly, the changes that were observed in the mechanical strength of the joints are consistent with the plasticization of adhesive in the joint rather than failure at the substrate interface. Ageing at 70°C did, however, indicate that there were changes in the interfacial layer and these can be correlated with the change in the failure mechanism. It was also observed that the titanium/zirconium (Ti/Zr) pretreatment showed signs of being less durable than the others used in this study. Copyright © Taylor & Francis Inc.
Original language | English |
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Pages (from-to) | 1199-1215 |
Number of pages | 16 |
Journal | Journal of Adhesion |
Volume | 81 |
Issue number | 12 |
DOIs | |
Publication status | Published - Dec 2005 |
Keywords
- Adhesive durability
- Dicyandiamide cure
- Dielectric spectroscopy
- Epoxy resin
- Moisture ageing
- Pretreatments