Cold Spray of Polystyrene Particles on Various Substrates

Author: Şebnem Özbek, Department of Chemical and Biological Engineering

Mentor: Michael Carter, Arbegast Materials Processing and Joining Laboratory (AMP)

Mentor: Dr. Travis Walker, Department of Chemical and Biological Engineering

Mentor: Dr. Grant Crawford, Department of Materials and Metallurgical Engineering

Cold spray is a well-known 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. During the cold-spray process, particles are accelerated to high speeds through a converging and diverging nozzle with a pre-heated, high-pressure gas. At high enough velocities upon impact on a substrate, particles deposit to form a non-porous coating on the substrate 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. This study focuses on cold-spray deposition of polystyrene particles on a variety of polymeric and aluminum substrates. A variety of different process conditions were studied to achieve buildup of particles on the substrates. Imaging analysis was performed to characterize the deposition thickness on each substrate. Promising results were obtained with polymeric substrates when the gas temperature and the substrate heating was kept around the glass-transition temperature of the particle. 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 whole process.