A Modeling Study of Bonding Mechanisms Between Similar and Dissimilar Materials in Cold Spraying on Polymeric Substrates

Molecular Weight Controls Interactions between Plastic Deformation and Fracture in Cold Spray of Glassy Polymers

“…For simplicity, these two parameters were assumed to be independent of molecular weight. β in eq represents the Taylor–Quinney coefficient, taken to be 0.9 in the present study . Numerical values for the JC model parameters as well as all other mechanical and physical properties used in FE analyses are listed in Table .…”

“…As such, the significant role of temperature was further highlighted by preheating polymer particles above their glass transition temperature, confirming particle preheating as a practical solution to achieve higher deposition efficiencies and a lowporosity deposit. Singh et al 9 reported the effect of relative deformability of particles and substrates on deposition mechanisms of polyetheretherketone (PEEK), acrylonitrile− butadiene−styrene, and copper particles on PEEK substrates. Their numerical findings indicated that the deposition is governed by the plastic deformation of the particle in soft particle/hard substrate cases.…”

“…Manufacturing of polymers and polymer-based composites has been facilitated by concurrent advances in cold spray technology and growth in the number of applications of polymers in various industries. − When used as cold spray feedstock, polymer particles behave quite differently than metals. The differences between the impact response of polymeric and metallic feedstock mainly originate from the significant differences in their thermo-mechanical properties, the nature of the bonds formed (e.g., metallurgical and metallic bonds in metal cold spray, which do not necessarily apply to polymer cold spray), as well as the material’s location on the crystalline-amorphous spectrum.…”

“…The differences between the impact response of polymeric and metallic feedstock mainly originate from the significant differences in their thermo-mechanical properties, the nature of the bonds formed (e.g., metallurgical and metallic bonds in metal cold spray, which do not necessarily apply to polymer cold spray), as well as the material’s location on the crystalline-amorphous spectrum. Regardless, the occurrence of extremely high strains and strain rates in both the impacting particles and the substrate is the main driving force for a successful deposition of cold-sprayed powders. − The high local strain fields developed at the particle–substrate interface vicinity lead to adiabatic heating and substantial local thermal softening, effectively improving the mixing between the two components. − However, when both the particle and the substrate are polymers, other mechanisms can arise subsequent to the local heating: mechanical mixing, interlocking, and entanglement between the polymer in the impacting particle and the polymer constituent in the substrate. In such cases, the rheological behavior of the constituent polymer species can also play a major role in the establishment and strength of the bond. − …”

“… 10 − 17 The high local strain fields developed at the particle–substrate interface vicinity lead to adiabatic heating and substantial local thermal softening, effectively improving the mixing between the two components. 9 − 11 However, when both the particle and the substrate are polymers, other mechanisms can arise subsequent to the local heating: mechanical mixing, interlocking, and entanglement between the polymer in the impacting particle and the polymer constituent in the substrate. In such cases, the rheological behavior of the constituent polymer species can also play a major role in the establishment and strength of the bond.…”