An Experimental and Finite Element Study of Cold Spray Copper Impact onto Two Aluminum Substrates

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 A degrees 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 mu m 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 A degrees C, the effect of substrate heating by the gas jet could not be ignored.