The effect of cold spray temperature and substrate hardness on particle deformation and adhesion has been studied, with particular emphasis on adiabatic shearing leading to melting. Copper particles were cold sprayed onto commercial purity (CP) aluminum and alloy 7050-T7451, with stagnation temperatures 200, 400, and 600°C. Deposition efficiency, assisted by particle embedding, increased with temperature and was higher on the softer CP substrate. Crater surfaces, adhered particles, and interfaces were characterized by scanning electron microscopy, focused ion beam, and transmission electron microscopy. For comparison, the impact of 15 lm Cu particles was simulated using finite element modeling. A thin layer of material on the substrate-side of the interface was predicted to reach melting point on both substrates at higher impact velocities. Formation of a molten layer was found experimentally. At 600°C, the effect of substrate heating by the gas jet could not be ignored.

The study demonstrates that embedment of copper particles into thermoplastic polymers (polymers) using cold spray technology is an effective deterrent against fouling organisms. Two polymers, high-density polyethylene (HDPE) and nylon were metallised with copper powder using cold spray technology. After 250 days in the field, Cu-embedded HDPE and copper plate controls were completely free of hard foulers compared to Cu-embedded nylon and polymer controls which were heavily fouled with both soft and hard fouling. Antifouling (AF) success is related to the interaction between the properties of the polymers (elastic modulus and hardness) and the cold spray process which affect particle embedment depth, and subsequently, the release of copper ions as determined by analytical techniques. Embedding metal using cold spray equipment is shown to be an effective AF technology for polymers, in particular those that are difficult to treat with standard AF coatings, with efficacy being a function of the interaction between the cold spray metal and the polymer recipient.

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