Fast Infrared Thermal Imaging for Determining Particle Velocity and Temperature in Cold Spray Applications

Cold spray is an important technology for producing uniform coatings on a variety of surfaces. Particles comprised of metals, polymers, composites, and other materials are supersonically ejected from a nozzle an impacted onto a surface where they bind via deformation. Critical to optimizing the technique is an understanding of the particle velocity and temperature. In this work, a high-speed broadband infrared thermal imaging camera was used to conduct in situ measurements of particles during several cold spray experiments. Particle velocities were determined from individual images recorded at frame rates exceeding 10 kHz, and temperatures were computed from the observed thermal radiance based on known ambient conditions and material emissivities. Details of the experimental configurations and data processing computations will be presented with an emphasis on the applicability of this approach for optimizing cold spray processes for industrial applications.