Effects of Cold Spray Repairs on the Mechanical Properties of a Component

NPS NRP Executive SummaryCold dynamic gas spray, better known as cold spray, has generated much interest for repairing metallic components and depositing protective metal coatings. Naval shipyards recognize the potential of this technology to provide rapid repair and manufacturing capability and to replace welding as the state-of-the-art for metal joining and repairs. As cold spray evolves into a mature technology, there is a need to understand the mechanical behavior of widely used engineering alloys such as the cupronickel alloys. This study investigates the mechanical behavior of Cu-38Ni coatings cold sprayed onto Cu-10Ni substrates with and without an annealing heat treatment. The cold sprayed coated specimens undergo uniaxial tensile tests to study the durability of the cold sprayed coating layer and its effects on the overall mechanical behavior of the coated substrate. Annealing at 650 °C is found to enhance both the ductility and strength of the coating material. The annealed coating specimen experiences an elongation to failure of ~13.7%, while the as-sprayed specimen only experienced ~3.9% elongation. Adhesion tests show that annealing leads to a large increase in adhesion strength of the coating to the substrate due to solid state diffusion across the interface during the heat treatment. Annealing further leads to a reduction in pores, intersplat cracks and porosity, and a more ductile and tough material due to recrystallized grains. Nanoindentation reveals that the cold as-sprayed material is the hardest, but also the most brittle, exhibiting plasticity of only 81%, as compared to 89-90% for the annealed coating and the substrates.Naval Sea Systems Command (NAVSEA)ASN(RDA) - Research, Development, and AcquisitionThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.