Adhesion properties of novel corrosion resistant hybrid structures

Hybrid structures are widely used since they enable unique combinations of properties for the final structure. Within polymer/metal hybrids, stainless steel instead of more regularly used mild steel or aluminium is a tempting choice but it is difficult to join adhesively. Thus improved solutions for the stainless steel joining with polymeric materials are needed. This study concentrates on the idea of utilisation of thin rubber layer as an adhesive between stainless steel and glass fibre reinforced epoxy composite (GFRP). Both mild steel and stainless steel with different surface finishes together with GFRP laminates were used as substrates for the ethylene propylene diene (EPDM) based rubber. The adhesion and microstructure of the interfaces were characterised. Transmission electron microscopical (TEM) studies indicated that a close contact between the components can be achieved and thus high quality interfaces are created by vulcanising the rubber to the steel or GFRP surface without pre-treatments. Stainless steel/rubber/GFRP hybrid structures where the strength of the steel/GFRP joint is defined by the cohesive strength of the rubber can be manufactured, as seen from the results of the peel tests. Since the fracture is located inside the rubber and not at the interface, the prediction of the structure's behaviour is also easier.