Design, Construction, and Characterization of a Thermal Spray Coating Aerosol Generator

Applications for thermal spray processes have a broad range across all industrial sectors. In metal spray coating processes, large quantities of aerosols composed of fine and ultrafine metal particles are generated. Little is known about the physical (e.g., particle size and morphology) and chemical (e.g., metal composition, solubility, surface chemistry, metallurgy) properties of the aerosols formed during thermal spray coating. The goal was to design and construct a computer-controlled, automated spray coating system to characterize the properties of the formed aerosols during different spray coating processes in a well-controlled laboratory setting. Aerosols from both flame and cold spray are being evaluated. It has been observed that 80-95% of the particles generated during thermal spraying are in the ultrafine or nanometer-sized range with diameters <100 nm. The generated particles were primarily composed of chromium, nickel, cobalt, zinc, and aluminum, depending on the process and materials used. An understanding of the physical, chemical, and metallurgic properties of the aerosols formed during spray coating may improve process development and technology.