Adhesion improvement between epoxy and stainless steel using a silane coupling agent in an atmospheric plasma process

Abstract

3-Aminopropyltriethoxysilane coatings have been deposited on stainless steel (SS) samples by means of an atmospheric pressure dielectric barrier discharge as an adhesive promotion layer in epoxy resin/SS composites. A multi-diagnostic analytical approach (FTIR, XPS) was used for the chemical characterization of the deposited coating with regard to improvement of adhesively bonded joint strength. The effect of a plasma post-treatment after the plasma coating deposition was compared to a thermal post-treatment. Both enhanced the siloxane networking resulting in a significant adhesion improvement. Fracture strength between SS and epoxy was increased with more than 20MPa. Atmospheric plasma deposited siloxane coatings including a plasma post treatment improve the adhesion strength in stainless steel/epoxy hybrids with 20MPa compared to untreated steel samples. Therefore these plasma coatings can be seen as worthy alternatives to more conventional wet chemical coatings with a thermal post treatment.