Cold spray technology to promote conductivity of short carbon fiber reinforced polyether-ether-ketone (PEEK)

Recent studies showed that cold spray is a suitable way to produce metallic coatings on non-metallic surfaces such as polymers and composites for engineering applications. Mechanical bonding and particle anchoring process onto these substrates have not been totally understood yet. This study is focused on the creation of conductive coatings by cold spray onto short carbon fiber reinforced PEEK. For the requirements of the industrial application, the deposit should be able to tolerate both electrostatic and electric currents (higher than 10A). Because of their high conductivity, aluminium and copper powder seemed to be the best candidate materials. To promote adhesion and coating build up, copper-zinc and copper-PEEK mixed powders were also tested. A correlation between experimental and numerical tests has been adopted to assess and improve the possibilities of this material coupling. Both low pressure and high-pressure cold spray equipment were used for the spraying. Since polymer matrix-based composites are thermosensitive materials, it was necessary to develop a computational fluid-dynamics tool to investigate the interaction of the hot gas on the substrate and the correlation with the deposition process. A series of finite element simulations of single and multi-particle impacts onto local structures of the composite, as observed from SEM images of the specimens, is on-going. A classical pull-off test of the specimen will be adopted to collect data about coating adhesion strength. Finally, the four points measurement by Van der Pauw method will be used to assess the conductivity of specimens for different powders and coating thicknesses.