Adhesion and mechanical performance of co-consolidated titanium-thermoplastic composite joints

Co-consolidation is a technology to manufacture metal-thermoplastic composite (TPC) joints. With this technology, metal inserts can be integrated in a composite structure during a standard consolidation or forming process. By heating up the two materials, the thermoplastic resin melts and acts as an adhesive, thereby achieving composite consolidation and bonding to the metal simultaneously. Thus, the co-consolidation represents a time and cost-efficient joining alternative to conventional fastening and adhesive bonding. The implementation of the co-consolidation technology requires developing manufacturing and processing guidelines which ensure reliable metal-TPC joints. Therefore, the objective of this research is to understand, describe and optimize the adhesion mechanisms between metal and TPCs, more specifically between Ti6Al4V and C/PEKK composites. The results show that the adhesion between Ti6Al4V and PEKK relies on physical interactions. Pretreating the titanium surface using grit-blasting in combination with a novel silane-polydopamine coating is essential to achieve a stable and tough Ti6Al4V-C/PEKK interface. This fundamental understanding of the interface led to the development of a demonstrator of which the geometry is inspired by a wing spoiler, where a metal lug is joined to a composite panel. This geometry allowed to explore a co-consolidation manufacturing route and evaluate the mechanical performance of a Ti6Al4V-C/PEKK part.