Abstract

In the presented research effort, cyclic polarization tests were conducted coupled with acoustic emission measurements, in order to monitor the corrosion phenomena. Previous studies have shown that epoxy composite coatings offer satisfactory corrosion protection to aluminum substrates minimizing and even eliminating some degradation phenomena. In the present effort, acoustic emission was applied during potentiodynamic cyclic polarization testing on as received, anodized and carbon epoxy coated aluminum substrates in order to correlate corrosion phenomena, like oxide layer development and localized corrosion, with characteristic acoustic emission signal descriptors. The epoxy coating was used both as received and as reinforced with various carbon fillers i.e. carbon nano-tubes, amorphous graphite or a combination of them. Acoustic emission detected signals due to hydrogen bubble related processes during cathodic polarization and signals due to deposition of thick soluble films during the final stage of anodic polarization. The acoustic profile between coated and uncoated aluminum substrates, exhibited substantial changes dependent both on the surface preparation and the employed reinforcing filler. The overall outcome of the experimental results, indicate that with further research, acoustic emission can be employed as an Aluminum Corrosion Monitoring tool.