Fused filament fabrication of ONYX-based composites coated with aluminum powders: A preliminary analysis on feasibility and characterization

Polymer-based AM methods are the most mature additive technologies for their versatility and variety of products obtainable. The addition of fibre reinforcement can also confer to the manufactures produced good mechanical properties. Unfortunately, several applications are still precluded because polymers cannot guarantee appropriate electrical conductivity, erosion resistance and operating temperature. Aiming to overcome these issues, the metallization of the surfaces emerges as a possible solution. Unfortunately, thermoplastic polymers exhibit thermosensitive behaviour and run the risk of being damaged when traditional metallization techniques, which require the melting of metal powders which will act as a protective coating. For this reason, studies have focused on Cold Gas Dynamic Spray, an additive manufacturing technology, which exploits kinetic energy to favour the adhesion of metal particles rather than the increase in temperature. In this work, a first attempt is made to verify the feasibility of cold spray coatings on 3D printed composite substrates, produced by means of Fused Filament Fabrication (FFF) technique. FFF technology allows the deposition of two different types of filaments by using a double extruder. These composite fibres within 3D printed parts manage to give the object a resistance comparable to that of a metal part with lower production cost and a high degree of automation. These structures, made of ONYX, a Nylon matrix in which short carbon fibres are dispersed, and reinforced with long carbon fibres, are designed to better fit the CS deposition. Aluminium coatings have been produced and a characterization campaign has been carried on.