Polymer matrix composites (PMCs) are the most used in aerospace fields due to their special mechanical properties coupled with reduced weight. Metallic structures can be manufactured on the surface of PMCs producing hybrid constructions with intriguing characteristics. The cold spray technology (CS) seems to be the best solution for the manufacturing of metallic coatings on polymer-based substrates. However, the last researches on PMCs metallization through CS were carried out without taking into account a proper manufacturing of the substrates. Therefore, the customized manufacturing of PMCs used as substrates for CS deposition represents a crucial aspect to be considered, the target surface should be designed and manufactured to fit better the CS requirements. In this scenario, the Fused Filament Fabrication method (FFF) is the best solution for tailored composites manufacturing. Therefore, this work aims to develop a novel manufacturing route to produce innovative composite structures by using the FFF technology for the 3D-printed polymer-based substrate and the cold spray technology for the 3D-printed metal deposition. The novelty is that, for the first time, the polymer-based substrates will be designed and manufactured “ad hoc” for the cold spray metallization by using the rapid prototyping 3D-printing process successfully integrated with CS technology. Graphical abstract

In the present work, the effects of oxidising and standard flame spray techniques on microstructure and wear performance of Low Velocity Oxygen Fuel NiWCrBSi coatings produced onto mild steel substrate were studied. Results showed that coating microstructure was dependent on the stoichiometry of the reacting gas mixture. Coatings produced in oxidising flame conditions showed higher amounts of semi-molten particles and high quantity of WC phases. Those coatings showed a good behaviour in dry sliding wear test, due to their higher hardness and the formation of compact and adherent oxide tribofilms. The wear behaviour of non-molten particles against friction forces is discussed, with the aim of establishing relationships between the tribological response of the material and its process-induced microstructure defects.

So short is the road from thermal spray to additive manufacturing, provided that cold spray is used. The latter is therefore the best liaison between the 2 domains as this contribution aims to show. For that purpose, prominent characteristics of both thermal spray and additive manufacturing are considered. Regarding powders, advanced particle classification using X-ray microtomography is shown to be a very powerful tool for the modeling of coating build-up. The porosity issue is then discussed from the observation of deposits using different densification conditions. The part devoted to polymers raises relevant points which are important when involving this specific type of material. This makes the link to a section on advanced mechanical testing of interfaces, including splat-to-splat interfaces within the deposit. From the discussion of all the previously-mentioned items, the various stages of development of cold spray are given and justified in the perspective of that of additive manufacturing.