(100f) Cold Spray of Polystyrene Particles on Various Substrates

Cold spray (CS) is a solid-state coating technique that has been used since the 1980’s for a wide range of applications for metals, polymers, ceramics, and composites on various substrates [1]. During the cold-spray process, particles are accelerated to high speeds through a converging and diverging nozzle with a pre-heated, high-pressure gas. Upon impact on a substrate, particles deposit to form a non-porous coating on the substrate that is caused by severe plastic deformation of the particle. The bond that forms between the particle and the substrate can be metallurgical, chemical, or mechanical. Cold spray of polymers has been investigated to a lesser extent than metals, and since polymers behave significantly differently than metals during the cold-spray process, many unknowns still exist [2–5]. Cold spraying of polymers have many current and potential applications, including surface protection from corrosion [6], protection from cavitation erosion or mechanical impacts [7], electronic applications [8, 9], and biocompatible and antibacterials coatings [10, 11]. However, the deposition efficiency of polymer cold spraying (10%) is very low when compared to metal cold spraying (∼100%).

This study focuses on cold-spray deposition of polystyrene particles on polymeric and aluminum substrates. A number of different process conditions were investigated to achieve buildup of particles on the substrates. Analysis was performed to characterize the deposition thickness on each substrate. Promising results were obtained with polymeric substrates when the gas temperature and substrate heating was kept around the glass-transition temperature of the particle. As shown in figure, with 10 passes, 15 μm deposition was obtained at these conditions. The deposition on the aluminum substrates is still an ongoing investigation that is mainly focused on the first-layer adhesion, since the first couple of layers of deposited particles plays a key role during the process.

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