Deposition of Thick Copper Cold Spray Coatings on Steel for Used Nuclear Fuel Repository Using Nitrogen and Pulsed Waterjet Surface Preparation

This study demonstrates a new approach for producing thick copper coatings on steel by cold spraying via nitrogen gas. To overcome delamination problems without resorting to helium, substrate surfaces are treated prior to deposition using a forced-pulse waterjet. Samples with different levels of roughness were prepared using both conventional and waterjet surface treatments. The samples were then coated with thick Cu using only N₂ and adhesion tests were performed. Test results show good coating adhesion on all waterjet treated substrates with bond strengths ranging from approximately 25 MPa to 58 MPa, depending on surface roughness. Consistent with previous studies, cold spray Cu did not adhere to any substrates that had been polished or grit blasted. It is shown that the pulsed waterjet creates a surface with anchoring features that interlock with incoming particles to form a strong mechanical bond.