Cold Spray Multilayer Metal Build-Up on a Polymeric Substrate

Copper (Cu) and Tin (Sn) were low-pressure cold sprayed onto polyamide 6 (PA 6) and polypropylene (PP) substrates. The first layer of Sn and Cu was built onto the polymer substrate and continued as an alternative layer of Cu and Sn build-up under controlled process parameters. The chronological order of either first spraying Cu or Sn does not hinder building a coated layer on the PA 6 and PP substrate. The coating thickness can reach as thick as 100 μm of the PA 6 (Cu/Sn/Cu) layer. Results show the potential ability for additive manufacturing using polymeric templates. The cold spray kinetic bonding of the metals avoids any intermediate phase formation. The mechanical performance of the coated material remains the same as the deposition process does not degrade bulk substrates. The contour of the interface and the surface roughness resulting from the cold spray coating process lead to a deformed surface layer of the polymer on the particle size of the powder used for cold spraying. While the metallic coating deforms via plastic deformation and cracking, the through-thickness cracks, which primarily are perpendicular to the loading direction, do not span the width of the coating due to the tortuous nature of the microstructure. The advantage provides electrical conductivity to strains of up to 10% and maintains a low electrical resistance.