Surface treatment of additively manufactured parts for improved bonding with fiber reinforced polymer composites

The aim of this study is the investigation of Diamond-Like-Carbon (DLC) and organosilane coatings as adhesion promoters for additively manufactured aluminium adherends to be co-bonded with carbon fiber prepreg for sandwich applications. Screening experiments were conducted to assess epoxy wetting behaviour of the coatings in function of substrate surface roughness. Based on these findings, the highest and lowest performing surface treatments were characterized by double lap shear testing. A DLC coating was found to foster epoxy wetting and to improve adhesion strength in mode II testing by 30% over the untreated aluminium reference. DLC coated honeycomb structures with as built surface roughness were found to have significantly increased adhesion to carbon fiber facesheets.