Numerical Studies on Cold Spray Particle Deposition Using a Rectangular Nozzle

Cold spray additive manufacturing (CSAM) is an emerging technique for scalable and rapid deposition of thick metallic coatings on various substrates. Despite great promises, CSAM with no upper limit of coating thickness remains challenging due to the stochastic nature of cold spray (CS) deposition. In particular, using axisymmetric nozzles (i.e., circular supersonic nozzles) lead to a quasi-Gaussian shaped particle distribution on the target surface, which limits the CSAM due to the formation of triangular-shaped (i.e., peak/valley-shaped) coating morphology. Recently, rectangular cold spray nozzles have been applied to CS particle deposition, and found to be promising for CSAM owing to its more uniform particle distribution and wider spray beam. In these studies, however, process-structure properties of cold spray deposition with a rectangular nozzle have not been sufficiently elucidated. Practical expansion of rectangular nozzles in CSAM strictly depends on uncovering process-structure properties of CS deposition phenomenon. To this end, we investigate cold spray deposition of microscale particles using a rectangular nozzle through three-dimensional discrete-phase turbulent flow modeling. The numerical modeling results are experimentally justified using a dual disc anemometer setup. The influence of operating gas conditions on critical particle deposition parameters is studied. An experimental case study of cold spray particle deposition on a polymer (ABS) substrate is also conducted to show the potential of rectangular nozzle in cold-spray based polymer metallization. The results suggest that cold spraying using a rectangular nozzle is beneficial for a more uniform, compact, and higher precision particle distribution on the target surface.