Insights on metallic particle bonding to thermoplastic polymeric substrates during cold spray

Metallization of polymers using cold spray technology has reached wide consideration in recent years. However, an effective modeling approach to address the deposition phenomena able to assess bonding formation in polymer metallization is still lacking. This study aims to develop a finite element model to simulate the solid-state deposition of metallic particles on thermoplastic polymeric substrates. Single copper particle impact on the Polyether Ether Ketone substrate was modeled using the coupled Lagrangian-Eulerian approach. Emphasis was given to the polymer material properties and substrate thermal history to account for the sensitivity of the physical and mechanical properties of polymers to temperature. Experimental coating depositions were performed to select an optimized set of spray parameters while single-particle impact tests were conducted for model validation. The substrate temperature was measured using an infrared thermal camera and was used to model the sub-surface temperature gradient during gas spray exposure. The proposed numerical model is shown to be capable of predicting various impact features includi mechanical interlocking and the effect of particle velocity fluctuations and temperature gradients on the extent of bonding. Substrate heating was found to have a distinct effect on the correct prediction of particle bonding. The proposed model enables tuning the appropriate processing conditions for successful copper particle adhesion on PEEK polymeric substrates.