Investigating the Feasibility of Metallizing Reprocessable Vitrimeric Components through Cold Spray Technique

Epoxy vitrimers, distinguished by their unique combination of the mechanical strength typical of thermosets with the reprocessability of thermoplastics, represent a promising class of materials for advanced technological applications. To optimize their performance in high-demand environments, surface functionalization of vitrimers and vitrimeric composites is crucial to enhance their durability and reliability in harsh conditions. This research work aims at studying the feasibility of metallising vitrimer-based components through cold spray technology. Aluminium coatings were applied under varying process parameters, inlet gas temperature (T = 150 –450 °C) and standoff distance (SoD = 70 mm–100 mm), to evaluate their impact on deposition quality and substrate behaviour. The deposition processes were performed on non-reinforced vitrimeric substrates as well as on vitrimeric matrix substrates reinforced with carbon fibre fabric. The results suggest that successful metallization occurs when the substrate temperature exceeds the topology freezing transition temperature (Tv ≈ 170 °C), enabling the ductile behaviour necessary for effective adhesion. At T = 300 °C and SoD = 100 mm, pure vitrimer coatings exhibited an average thickness of 50 ± 10 µm with minimal substrate deformation (grooves < 4% of panel thickness), while lower temperatures (T = 150 °C) resulted in brittle fracture and poor adhesion. Surface roughness increased from Sa = 0.15 ± 0.05 µm for uncoated substrates to Sa = 6.59 µm after coating. In contrast, composite substrates demonstrated enhanced stability due to fibre reinforcement, which constrained excessive substrate flow. At the best process conditions (T = 300 °C and SoD = 100 mm), composite panels achieved homogeneous coatings with Sa = 4.513 µm. However, excessive temperatures (T = 450 °C) led to substrate erosion and fibre damage in both pure vitrimer and composite panels.