Development of a cold-gas dynamic spraying system for parameter study of aluminium coatings

The objectives of this work were to develop a cold gas dynamic spraying set-up which sprayed aluminium powders with different microstructures, mainly conventional and nanocrystalline particles, and to determine which of the powders is most suitable for spraying. The development of the CGDS set-up included the numerical modeling of the supersonic gas flow; this lead to the design of the converging-diverging nozzle. Two sets of experiments were conducted to validate the model and design. The preliminary experiments were conducted using both conventional and nanocrystalline powders and the initial results showed that the nanocrystalline powders had a higher Vickers hardness. The nanocrystalline coatings were denser and adhered more evenly with the substrate. The second set of experimental work was conducted only with conventionally structured particles to determine the influence of three spraying parameters on the performance of the coating. (Abstract shortened by UMI.