Influence of laser-generated surface micro-structuring on the intrinsically bonded hybrid system CFRP-EN AW 6082-T6 on its corrosion properties

The corrosion behavior of a hybrid material consisting of intrinsically bonded carbon fiber-reinforced epoxy resin with laser-structured EN AW 6082 metal was investigated. Particular attention was paid to the effects of the laser-structuring, surface topography and the contacting. Pristine and hybridized specimens were corroded in aqueous NaCl electrolyte (0.1 mol/l) using a potentiodynamic polarization technique and subsequently analyzed using computed tomography, scanning electron-, light- and laser scanning microscopy. The results show that the corrosive reaction arises mainly from the aluminum component. Surface pretreatment of the aluminum resulted in increasing corrosion rates, but showed no influence on the hybrids corrosion properties. Optical micrographs suggest that the epoxy resin acts as a sealant preventing galvanic corrosion between the aluminum and carbon fibers by hindering the diffusion of the electrolyte into the joints. While corrosion effects were observed locally at the aluminum surface, they were, contrary to expectations, not enhanced on the hybrid interfaces.